US1495364A - Apparatus for obtaining serum from blood - Google Patents

Description

May 27 1924- w. B. WESCOTT APPARATUS FOR OBTAINING ssnum FROM BLOOD Original F iled Feb. 25

1920 2 Sheets-Sheet. 1

. w Willa M @an ATTORNEYS.

May 27 1924.

W. B. WESCOTT APPARATUS FOR OBTAINING SERUM FROM BLOOD Original Filed Feb. 25

1920 2 Sheets-Sheet Z FIG 12 FIG 9 FIG 10- ATTORNEYS.

Patented May 27, 1924.

WILLIAM BURTON WESCOTT, F WELLESLEY HILLS, MASSACHUSETTS, ASSIGNOR, BY

MESNE ASSIGNMENTS, TO AMERICAN PROTEIN CORPORATION, OF BOSTON, MASSA- CHUSETTS, A CORPORATION OF MASSACHUSETTS.

APPARATUS FOR OBTAINING SERUM FROM BLOOD.

Application filed February 25, 1920, Serial No. 361,258. Renewed October 22, 1923.

To all whom it may cmwmm:

Be it known that I, WILLIAM BURTON WESCO'I'I', a citizen of the United States, and

resident of VVellesley Hills, in the county of 5 Norfolk and State of Massachusetts, have invented new and useful Improvements in Apparatus for Obtaining Serum from Blood, of which the following is a specification.

This invention relates to apparatus for obtaining clear serum from blood. For human food or therapeutic purposes, it is in general necessary that serum be substantially free from haemoglobin, the presence of which in the normally pale yellow serum results in a change of color from yellow through light brown to a deep ruby. To obtain clear serum by the ordinary methods heretofore practiced it has been necessary to treat the serum chemically to remove coloring matter (haemoglobin) with which it becomes contaminated and stained during the separation of the serum. The object of the present invention is to provide means to separate serum from blood in such a way as to pre- 2 vent contamination of the serum by haemoglobin, to obtain from the blood the maximum possible amount of'serum, and to devise apparatus capable of performing the process on a--large and commercially profitable scale adaptable to slaughter-house conditions.

Blood,'from one point of view, .may be considered to be a fluid tissue composed of a transparent pale yellow liquid (the blood plasma) in which a vast number of particles (the red and white corpuscles) are suspended. It is a striking characteristic of blood that in general outside of the organism it coagulates to a jelly-like mass in a few minutes, generally from five to ten minutes after the blood leaves the body. In the coagulation of the blood a chemical transformation takes place in the plasma by which fibrinogcn, one of the proteins, separates out as an insoluble, stringy, solid fibrin. The transformation of fibrinogen into fibrin is believed to require the presence of an enzymotic substance found in serum and in fibrin, and generally designated as fibrin ferment or thrombin.' The formation-of fibrin ferment in uncoagulated blood is not clearly understood, but it is common knowledge that coagulation is stimulated by the addition of fibrin or serum.from previously'coagulated blood. The coagulation or the forming of the fibrin produces a spongy network of tendrils enmeshing the red and white corpuscles and enclosing, sponge-like, the fluids of the blood. Fibrin is formed throughout the entire mass of the blood and tends, after its formation, to contract. The velocity of coagulation and the contractibility of the resulting fibrin may vary over a Wide range; I

thus blood protected from foreign bodies, such as the walls of the receiver, dust, etc., as by collecting it in paraflined vessels or under oil, will remain fluid for hours or even days, while on the other hand, the addition of serum or fibrin from previously coagulated blood will cause rapid coagulation and produce a fibrin clot of marked contractibility. ()n contracting, the fibrin clot expresses a liquid, the blood serum. Serum differs from the blood plasma chiefly in the absence of fibrinogen, which has gone into the formation of fibrin. The serum expressed from the coagulum'by the contraction of the fibrin clot with the methods heretofore used is generally more or less colored,

.due to the presence of haemoglobin, the red colorin matter of the blood, in red corpuscles which have escaped from the fibrin tendrils, or haemoglobin which has been freed from the corpuscles by their mechanical rupture or otherwise. The red blood corpuscles in mammalia are round, bi-concave discs and are composed of two principal constituents, the stroma which forms the real protoplasm, and the intra-globular contents, which is chiefly haemoglobin. It is held in the literature that the stroma are a semipermeable protoplasmic structure soaked with haemoglobin, from which the haemoglobin. will be freed by mechanical rupture or by haemolysis, which latter occurs .when the osmotic equilibrium is disturbed, as by a solution of less concentration than the serum. For instance, upon the addition of water to the serum and the consequent dilution of the serum, the corpuscles swell, due

to the taking up of water, and the haemoglobin passes from the stroma into the serum. "Various chemical substances such as chloroform, and most alkalis, have a strong haemolytic action. The corpuscle is so delieats a structure that haemolysis is produced mechanicallyby rapid stirring and also by thawing after freezing.

The coloring matter, while in the corpuscles, may be removed from the serum by a centrifuge or by merely allowing the corpuscles to settle out. But such coloring matter as may have been freed from the corpuscles is very difiicult to remove without serious chemical modification of the serum itself. Known methods heretofore practiced of obtaining serum from blood may be divided into two groups. The first, which is the more generally practiced, consists in allowing the blood to clot in a large shallow vessel, cutting the clot into small cubes by means of a coarse meshed wire net, and spreading the cubes upon a fine wire net to drain. The second method consists in defibrinating the blood and removing the corpuscles either by passing the blood through a centrifuge or allowing it to stand and the corpuscles to settle out.

By the first method, the serum ylelded by the contraction of the fibrin in the small cubes is highly colored, both by red corpuscles and by free haemoglobin resulting from the mechanical rupture of the corpuscles during the severance of the clot. As the flow continues, serum from the inside of the cubes washes out the corpuscles which are not enmeshed, and also the haemoglobin of the ruptured corpuscles, so that the last of the yield is more nearly clear than the first.

But the percentage yield of serum even ap- 'proximately free of haemoglobin is very small. Furthermore, the long exposure to the air at room temperature (low temperatures materially reduce contractibility) results in the rapid growth of bacteria which unfits the product for human consumption. The second method gives a higher yield of serum free from blood corpuscles, but still too highly colored by free haemoglobin from cor uscles broken by the stirring by which de brination was efi'ected to be desirable as a food product. 4

Of the chemical steps capable of removing the haemoglobin, some disadvantageously modify the character and properties of the serum proteins, and of those which do not modify the protein properties, some are too costly to be of commercial interest and others cannot be used with safety to produce a product destined for human consumption.

In producing serum free of haemoglobin by expression from a contracting clot, it is necessary that the clot be uncut and unruptured, and also that the blood be caught and the clot formed in a vessel, the walls of which have been greased in order that the fibrin may be prevented from adhering. This is important for two reasons: first, were the fibrin to adhere, it would, upon the contraction of the clot, tear away from the walls, and in so doing liberate many red corpuscles, and also, which is more serious, rupture many others, thereby permitting free haemoglobin to escape into the serum. Secondly, the contractionof a clot free to contract is greater than that of a clot which has lost much of its contractibility in its efi'orts to tear itself free from the walls of the container. Consequently a greater yield is obtained when the clot is quite free to contract. As above pointed out, it is important that the walls of the container in which the clot is formed be greased or paraffined' to prevent adhesion of the clot. But this unctuousness tends to seriously increase coagulation time and decrease the contractibility of the clot. The process performed in apparatus of the present invention provides, as one of its steps, a method of so accelerating coagulation as to produce a dense clot, notwithstanding the fact that the container walls are greased. This step consists in introducing, in a commercially practicable manner, a powerful, sterile, fibrin ferment, and is preferably accomplished by allowing shreds of fibrin from the previous clot to remain adherent'to the coreabout which the clot forms. These fibrin shreds may be sterilized and dried without appreciable reduction of their enzymotic properties. It is obvious that the same end may be achieved by other means, such as the addition of serum to the blood, but because of the difficulties of sterilization of serum, we prefer to use fibrin.

It is also important, if clear serum is to be obtained, that the clot be formed in a vessel, the unctuous walls of which are perfectly dry, as the presence of water would produce hwmolysis and a consequent coloring of the serum by free haemoglobin.

In order to obtain the maximum yield of serum, it is also necessary that the clot be of such dimensions that the average distance which the serum has to travel through the clot to the surface is small. I have found that the limit of distance for obtaining substantially the maximum self expression of the serum is of the order of one-half an inch so that the maximum thickness of the clot to secure the best results should be at no point substantially greater than about an inch. As the clot contracts, the serum nearest the surface is first expressed with a resulting increase in density of the fibrin and blood corpuscles, until finally a balance is set u between the contracting force of the fibrin and the resistance opposed to the flow of the serum through the denser surface mass. For practical purposes, however, substantially complete self expression of the serum from a clot of normal contractibility may be accomplished if the serum does not have to travel through the clot more than about one-half an inch.

The present invention provides apparatus for so forming the clot as to provide this desired short average path to the surface, and also for suspending the clot so that substantially none of the outer surfaces are in contact with the walls of the container, and are thus all effective exit surfaces for the drainage of the serum. If no such support were provided, as for instance, if the clot were left to stand in a shallow pan, at least one exterior surface of the clot would not only be in contact with the vessel, but would have to support the weight of the clot and consequently would not function as an exit surface for the serum. Thus, for the same percentage of yield the clot would have to be correspondingly diminished in thickness. A further advantage of the present apparatus which is of commercial importance to expedite the expression of the serum as much as possible, is that the serum expressed from the clot is removed from contact therewith as soon as it is expressed, instead of being allowed to accumulate around 'the clot, thereby insuring that there will be no back pressure on the clot to prevent the ready expression and drainage of the serum.

As the yield of blood from a given animal,

such as a beef creature, is very large '(the blood, constitutes approximately th of the animals weight) and as the blood must be introduced into the container in which the clotting is to take place before the inception of coagulation, it is imperative that the operation be performed simply and expeditiously. On account of the short coagulation time, and the fact that an appreciable amount of time is required to drain the blood from the animal, it is as a practical matter necessary to catch the blood directly from the animal in the container in which the clotting is to take place. Hence the container must be of such shape and design as to be readily manipulated upon and as readily removed from the slaughter-house floor. It must be of such form that the resulting clot shall have a high specific surface, that is a high ratio of surface as compared to its mass, and during and after the expression of the serum it must be possible to remove the clot from the coagulating vessel without the least danger of rupture. That is, the clot must be removed as .a whole and provision should be made, as already explained, for lifting the clot after its formation in the vessel, to facilitate and expedite the expression and draining of the serum.

Figs. 4 and 5 are enlarged details in sectilon of the device for lifting the core and c ot;

Fig. 6 is a detail in side elevation of the end of the pipe through which the container is filled.

Fig. 7 is a plan view of a modified form of container, parts being broken away;

Fig. 8 is a vertical section on line 88 of Fig. 7;

Fig. 9 is a side elevation of the blood clots formed in the container of Figs. 7 and 8 and removed therefrom;

Fig. 10 is a plan view of another modification of the container, parts being broken away; I

Fig. 11 is a section on line 11-11 of Fig. 10;

'Fig. 12 is a plan view of another modification of the container, parts being broken away;

Fig. 13 is a section on line 1313 of Fig. 12;

Fig. 14 is a plan view of still another modification of the container, parts being broken away; and

Fig. 15 is a section on line 1515 of Fig. 14.

The form of container shown in Figs. 1, 2 and 3 is open at the top and comprises the outer side walls 7 and bottom wall 8. Convoluted or re-entrant inner walls 9 form a number of vertically disposed compartments 10 about an inch wide and similarly arranged at each side of a common central passage 11 (Fig. 1) which is also about an inch wide. Each compartment 10 and also the central passage 11 tapers or narrows toward the bottom to permit the clot to be more easlly and freely lifted out of contact with the walls,

and all compartments open directly into the common passage 11. Thus the interior of the container in which the clot is formed contains a number of re-entrant walls forming a chamber in which every point is distant from a wall within the limits of substantially complete or maximum self-expression of the serum.

A supporting core is arranged in the container comprising a top sheet 12 of wire screening or similar mesh and depending sheets 13 of similar screening extending downward through the centers of the several compartments 10. A depending central sheet 14, also of screening, extends down into the middle of passage 11 (Fig. 1). The entire composite core structure thus formed is carried by a central post 15, the lower endof which constitutes a Valve controlling the outlet spout 16 at the bottom of the container. This spout also is provided with a cook 17. At the top of the post 15 is a loop handle 18 by which the core as a whole may be lifted.

In order to position the core properly within the container and hold it at all points out of contact with the container walls, guiding members are provided at diametrically opposite corners comprising a slotted bracket 19 fixed to the top screen 12 and making sliding engagement with the tongue 20 of a fixture secured to a corner of the container. This fixture has a shoulder 21 which acts as a stop for the bracket 19 in'its lowermost position.

The cover of the container is removable and has an outer Wall 22 and an inner wall 23. The outer Wall has a rolled under edge 24 resting on the top of the-container walls 7 and a depending protective flange or skirt 25. A central inlet pipe or duct 26 extends through both walls 22 and 23. The pipe 26 has an inclined top 27. A removable cap 28 fits over the end of pipe 26 and has an inclined surface or cam 29 which raises and lowers thecap on the pipe 26 when the cap is rotated. Fixed to the cap 28 is a stem 30 which carries a projection or key 31 at its lower end adapted to pass through a key hole slot 32 in the handle 18 of the core when the cap is in its lowermost position. When the cap is rotated a part turn, the key 31 will turn out of register with the slot 32 and as the cam 29 lifts the cap, the latter, acting through the stem 30 and handle 18, will lift the wire mesh core.

The use'of the apparatus shown in Figs. 1 to 6 in performing the process is as follows:

The entire inner walls of the container are greased as by a coating of parafiin. The

parts are then assembled as shown in F igs.-

1, 2 and 3 with the core in position within the container, the cover closed, and the cook 17 closed. The delivery end 33, Fig. 6, of a pipe 34 which is directly connected to the animal being bled, at the time of slaughter, by one of the forms of special trocar described in separate applications heretofore filed by me, is attached to the inlet pipe 26 and firmly held thereon by the bayonet joint consisting of slot 35 and pin 36. As the bleeding proceeds, the blood flows, wholly under cover, and so protected from contamination and dripping or spattering water, directly from the interior of the animal to. the interior of the container until the latter is filled to a level above the top screen 12. Overflow holes 37 just above the level of the lower edge of flange 25 and protected thereby from outside dirt or foreign matter, are provided, as many as desirable to permit the escape of froth and so that the level of the blood will not rise too high. The pipe terminal 33 is then removed and the cap 28 set in place in its lowermost position with the hook or key 31 extending through the slot in the handle 18.

As the blood is warm, any water vapor which might tend to condense and form on the under side of the cover 22, which is in contact with the cooler outer air, will either.

flow down the under side of the cover 22 or drip on to the inner cover 23 and flow down the surface of either one or the other of said covers into the trough formed by the rolled under edge 24:, whence it will drip through holes 38 (Fig. 3), outside of the container, thus preventing access of water to the clot and consequent haemolysis, as already ex plained. The holes 38 and also the holes 37 perform the further office of permittingair to escape as it is displaced by the inflowing blood.

In the presence of fibrin ferment, more or less uniformly distributed over the wire mesh core, coagulation begins almost immediately, and in a very few minutes a clot is formed about and through the wire mesh core with re-entrant surfaces conforming in shape to the shape of the interior walls of the container. Thus a clot is produced of large specific surface as compared to its mass, all points within the clot being distant from the surface within the limits of approximately the maximum self expression of the serum.

After the clot is completely formed and has begun to contract, the cap 28 is given a half turn causing the cam surface 29 to ride up on the cam surface 27, thereby lifting the core a short distance guided by the sliding connections 19 and 20, and drawing the clot as a whole out of contactwith the converging walls of the container. The greased walls of the container will prevent the clot from adhering and being ruptured.

The clot is supported by the core in this slightly raised position, uncut and unrupt-ured, until the serum is expressed by the gradual contraction of the clot. The entire surfaceof the clot being held out of contact with the Walls of the container constitutes an effective exit surface through which the serum may be expressed. The serum will come off unstained by the blood corpuscles or haemoglobin, since the red blood corpuscles are not ruptured and are enmeshed and held by the fibrous network of the clot.

The raising of the core will lift the valve formed at the lower end of post 15 from its seat on the delivery spout. During the expression of the serum it is possible to leave the cock 17 of the outlet spout 16 closed, in which case the expressed serum will be held in the container around the clot as the latter contracts and expresses the serum. However, in order to secure the maximum yield and to hasten the expression of the serum, the cock 17 may be opened so as to drain off the serum into asuitable receiver as fast as it is expressed. This prevents any back pressure caused by the serum surrounding or contacting with the clot which tends to retard the expression of the serum from the clot and ultimately to balance and offset the capacity of the clot to contract further, before the maximum degree of self expression of the serum is achieved.

Referring now to the modification shown in Figs. 7 and 8, the rectangular container 40 is divided by partitions 41 into a number of independent or non-communicating rectangular compartments 42. A supporting core 43 of wire gauze or similar mesh depends into each compartment from a top sheet of mesh 44, the entire structure being manipulated by handle 45. A suitable cover, not shown, may be provided for this and also for the other forms hereinafter described. When the container is filled with blood by pouring into the top in the region of the center of the container, the middle compartments will first be filled and the blood will overflow from .them into the next adjacent compartments and. so on.

If the container is not filled above the level of the walls 41 it will usually result in practice that as the compartments are independent instead of intercommunicat-ing the more remote or end compartments may not always be filled quite as full as the middle ones. Separate clots will then be formed on the several cores 43 as illustrated at 46 in Fig. 9. These may. all be lifted out of the container together on the single core frame and may be suspended over a suitable receiver 47 fer the draining of the serum. If, on the other hand, the container 40 is filled above the level of the walls 41, and particularly if it is filled above the level of the horizontal mesh sheet 44, a horizontal clot member connecting the several depending clot members will be formed, resulting in a single integral clot with re-entrant surfaces, all parts of the clot presenting the characteristic short average path from the interior of the clot to the surface.

In the modification shown in Figs. 10 and 11,.the rectangular container 48 is provided with a number of separate cylindrical compartments 49 which may be filled in the same manner as the separate compartments of the container shown in Figs. 7 and 8.

Into each compartment 49 there depends a small tubular core 50 of wire mesh supported by the top sheet of mesh 51. These tubular cores may readily be cleaned by running a brush or the like through them. The use of the device is substantially the same as of the form last described.

Figs. 12 and 13 show a circular container 52 having concentric Walls 53 interrupted as shown to form a common passageway 54 connecting the several curved compartments 55 each with all of the others. The supporting core comprises concentric cylindrical sheets 56 of mesh depending into the middle of the curved compartments and the depending cross sheet 57 which extends through the middle of passage 54,. These members all depend from the horizontal top sheet of mesh 58. As the compartments in this form of container are all connected through the passage 54 a single integral clot will be formed with re-entrant surfaces whether the blood is filled above the walls 53 or not. The use of the device is substantially as already described.

In the modification shown in Figs. 14 and 15, the container 59 is circular and the concentric walls 60 are continuous instead of interrupted as in the form last described, thus forming independent or non-communicating concentric compartments 61. The core structure comprises the top sheet 62 and the depending concentric cylindrical sheets 63 of suitable mesh extending downward into the circular compartments. If the container is not filled above the tops of partitions 60 a number of separate annular clots will be formed, but if it is filled above the top of sheet 62 a single integral clot with re-entrant surfaces will be formed upon the core structure.

In each form it will be observed that the partition walls are tapered toward the bottom so that the clot will not adhere to the walls but may readily be lifted out without tearing.

It will alsobe understood that the walls of the container, of whatever form, should be greased as described in connection with the container first referred to, and also that it will be desirable to introduce a fibrin ferment by allowing shreds of fibrin properly sterilized from the previous clot to remain adherent to the core about which the clot forms.

In each form of the apparatus hereinbefore described, a large quantity of blood may be treated at one time, and a clot of large mass may be formed and manipulated at once, while at the same time preserving the necessary andcharacteristic thin clot with large specific surface.

The art or method herein described for obtaining clear serum from blood constitutes the subject-matter of an application for Let- 7 which the clot forms.

2. Apparatus for obtaining serum from blood comprising a container having unctuous interior Walls adapted to hold the blood for the formation of a clot, and a removable core in the container about which the clot forms.

3. Apparatus for obtaining serum from blood comprising a container adapted to hold the blood for the formation of a clot, and a removable core of mesh in the container about which the clot forms.

4. Apparatus for obtaining serum from blood comprising a container, the interior of which is so sha ed as to form a thin clot with large speci c surface as compared with its mass, and a core in the container about which the clot forms.

5. Apparatus for obtaining serum from blood comprising a container having re-entrant interior walls, and a core in the container about which the clot forms.

6. Apparatus for obtaining serum from blood comprising a container having re-entrant interior walls, and a core in the container shaped to conform to the general shape of the space formed by said reentrant walls.

7. Apparatus for obtaining serum from blood comprising a container adapted to hold the blood for the formation of a clot,

and a removable core in the container about which the clot forms, said core having thereon a fibrin ferment.

8. Apparatus for obtaining serum from blood comprising a container having a plurality of compartments, and a core having a plurality of members about which the clot forms extending into the-several compartments.

9. Apparatus for obtaining serum from blood comprising a container having a plurality of intercommunicating compartments, and a core having a plurality of members about which the clot forms extending into the several compartments.

10. Apparatus for obtaining serum from blood comprisin a container having a plurality of upstan ing Walls dividing the coni tainer into a plurality of compartments open at the top, and a core having a plurality of depending members about which the clot, forms extending down into the several compartments.

neoaeee tainer into a plurality of intercommunicating compartments open at the top, and a core having a horizontal member extending over the tops of the compartments and a plurality of depending members about which the clot forms extending down into the several compartments.

12. Apparatus for obtaining serum from blood comprising a container having a plurality of upstanding walls dividing the container into a plurality of compartments Whose transverse dimensions diminish from the top toward the bottom, and a removable core having a plurality of members about which the clot forms extending down into the several compartments.

13. Apparatus for obtaining serum from blood comprising a container having a plurality of upstanding walls dividing the container into a plurality of compartments open at the top, and a. core having a horizontal member extending over the tops of the compartments and a plurality of depending members extending down into the several compartments.

14:. Apparatus for obtaining serum from blood comprising a container having a plurality of compartments open at the top and diminishing in transverse dimensions from top toward the bottom, a core having a plurality of members extending down into the several compartments, and means to support the core at difiterent elevations, whereby after the clot is formed it may be lifted and supported in raised position for the better drainage of the serum.

15. Apparatus for obtaining serum from blood comprising a container having entrant interior walls and an outlet port in the bottom, a core in the container about which the clot forms, and a valve carried by the core controlling said outlet port,

16. Apparatus for obtaining serum from blood comprising a container in which the serum is separated from the blood, and means above the level of the blood for preventing the vapor rising from the blood fromfalling back into the blood as moisture of condensation.

17. Apparatus for obtaining serum from blood comprising a container in which the serum is separated from the blood, and means above the level of the blood for condensing the vapor rising from the blood and conducting it from the container.

18. Apparatus for obtaining serum from blood comprising a container in which the serum is separated from the blood, and means above the level of the blood for condensing the vapor rising from the blood and conducting it from the container, said means llll including a trough extending around the periphery of the container to catch the moisture of condensation.

19. Apparatus for obtaining'serum from blood comprising a container in which the serum is separated from the blood, and means above the level of the blood for condensing the vapor rising from the blood and conducting it from the container, said means including two superposed condensing surfaces and a trough extending around the periphery thereof to catch the moisture of condensation.

20. Apparatus for obtaining serum from blood comprising a container, a. cover adapted to conduct moisture of condensation, which forms on the interior surface of the cover, outside of the container, and an inlet duct extending through the cover.

21. Apparatus for obtaining serum from blood comprising' a container, a cover having an outer wall and an inner wall, the" latter being adapted to conduct moisture of condensation, which forms on the interior surface of the cover, outside of the container, and an inlet duct extending through both Walls of the cover.

22. Apparatus'for obtaining serum from blood comprising a container, a cover having an-inlet duct extending therethrough, and a pipe for connection to the animal being bled attached to said inlet duct.

23. Apparatus'for obtaining serum from blood comprising a container, a cover hav-,

ing an inlet duct extending therethro-ugh,

and a ipe for connection to the animal being bled removably attached to said inlet duct.

24'. Apparatus for obtaining serum from blood comprising a container having upstanding walls dividing the container into compartments, the outer walls of the container having one or more overflow vents located above the level of the tops of the division Walls.

25. Apparatus for obtaining serum-from blood comprising a container having one or more overflow vents in the upper part of its side walls adapted to limit the height to which the. blood may rise in the container, and a cover for the container haw ing a depending flange disposed exteriorly to the container and spaced therefrom adapted to shield said vent or yents. o 26. Apparatus 'for obtaining serum from blood comprisinga container, and a cover having at its periphery a trough to catch moisture of condensation which forms on the interior surface of the cover,-said trou h having drainage apertures opening; outsi eof the container, the container having one or more overflow vents located in the upper part of its side walls but below the level of the top of said trough, whereby the. blood will'be prevented from rising to a height sufiicient to come into contact with said moisture of condensation.

Signed by me at Boston, Massachusetts, this 18th day of February, 1920. WILLIAM BUR-TON WESCOTT.

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