1. Appln. o.42892/2 C L A I S . 1 · Means for ejecting in one stroke a speci ic minute amount of fluid sample* said ejection means including means for receiving and temporarily storing a given amount of fluid sample, said receiving and storing means having a very small outlet orifice, a solid thermal expansion device which is mounted within said receiving and storing means and which includes an e&ectric heating element, an expandable element which surrounds said heating element, which is made from a material having a given thermal coef icient of expansion and which has a given volume, and an insulating jacket surrounding said expandable element and said heating element, and means for supplying a predetermined amount of energy to said thermal expansion device to raise the temperature of said device to cause said device to expand thereby to eject in one stroke through said outlet orifice a specific minute amount of fluid sample from said receiving and storing means* 2. The ejecting device according to claim 1 vherein said receiving and storing container is a syringe* 3* The ejecting device according to claims 1 or 2 vherein said receiving and storing container includes a body having a fluid receiving cavity therein and said outlet orifice being in a vail of said body and communicating vith said cavity, said solid thermal expansion member being situated within said cavity* 4. The ejecting device according to any of claims 1 to 3 vherein said energy suplly souree includes a voltage source having good regulation to provide a substantially constant voltage independent of current drain. r h e ating element, an expandable clcmc fe-which suriroimds~sriA' 4 5.6.x The ejecting device according to claim J£ wherein said expandable element is made of silver. 4 6. J3& The ejecting device according to claim $ wherein said expandable element is made of beryllium oxide. 4 7· The ejecting device according to claim 5 wherein said expandable element is made of silver and beryllium oxide. 4 8. bs The ejecting device according to claim ? wherein said heating element is a wire conductor and said expandable element includes an elongated core on which said wire conductor is wound, said heating element and said core being embedded in a body which forms part of the expandable element. 8 9. ¾®s The ejecting devi © according to claim wherein said core and said body are made of the same material. 10. 4¾0 The ejecting device according to any of claims 54 to i¾ wherein said energy supply source includes an energy storing device for storing a predetermined amount of energy and a switch for connecting said storage device to said heating element to discharge said predetermined amount of energy from said storage device into said electric heating · '·Α£χ The ejecting device according to claim 1Φ wherein said thermal expansion member includes circuitry connected to said switch and said heating element for monitoring the energy input to said heating element and for opening the connection between said voltage source and said heating element after a predetermined amount of energy has been supplied to said heating element. 11 12. jJaJj; The ejecting device according to claim Ws. wherein said circuitry includes an integrator for integrating the current flowing through said heating element, a second vol¬ tage source, a relay including an operating coil and contacts in the connection between said first voltage source and said heating element, and a comparator having inputs connected to said integrator and said second voltage source and an output connected to said operating coil, said comparator being operable to compare a voltage developed in said in¬ tegrator with a constant voltage supplied from said second voltage source and to energize said coil for causing opening of said contacts when said developed voltage equals said constant voltage. 13. ½u The ejecting device according to any of claims 1 12 to ^ΦΘ wherein said receiving and storing container includes an elongate hollow body, a projection which extends from said body, which is integral with said body, which has a cavity therein communicating with the hollow interior of said body, and which has a tip at the distal end thereof, said tip said outlet orifice having/an opening therein communicating with said cavity, and a plunger in said body, said plunger having a passage¬ way therein, said passageway having a first end which opens into said hollow body opposite a closed end of said hollow body and a second end which opens onto a side of said plunger and which is adapted to register and communicate with said cavity during at least a portion of the movement of said plunger within said body, and said thermal expansion member being situated in said cavity0 13 14. lex. The ejecting device according to claim wherein said body is open at one end opposite said closed end and said plunger has a portion thereof which extends outwardly from said open end of said body, and wherein said receiving and storage container includes means for limiting outward movement of said plunger to a position where said second end of said passageway is completely out of registry with said cavity. 15. xb6c The ejecting device according to claim Ϊ4Χ©Ί«Χ*5 13 o including structure for mounting said body in a particle study device with said tip in a predetermined position re¬ lative to a sensing zone in said particle study device. 16. ¾¾, The ejecting device according to any of claims 13 to φήχ^ ο β^ wherein said body has a hole therein opposite said projection and wherein a plunger is received in said body through an open end thereof and has a lateral passageway with the inner end of said cavity for enabling filling of said cavity with fluid sample through said hole and said passageway. 16 17. xb£k The ejecting device according to claim Y wherein the end of said body, opposite said open end thereof is closed, and said plunger has at least one channel therein communicating the space between said closed end of said body and the inner end of said plunger to atmosphere. 18. -4-9x The ejecting device according to claim 1, wherein the fluid sample contains a plurality of particles to be ejected into a flow stream leading to a sensing zone in a particle study device, the volume of said specific minute amount of sample being equal to the volume increase of said thermal expansion device. 17 19.¾®x The ejecting device according to claim ϊθ^ said ejecting device being associated with a particle study apparatus of the type wherein a fluid sample containing particles is passed from one body of electrolyte through an aperture to another body of electrolyte, wherein the impedance through the aperture is changed during the passage of a particle through the aperture and wherein the change of impedance is sensed and used to generate an electrical sig¬ nal representing a particle passing through the aperture, said ejecting device being constructed for ejecting the specific minute amount of fluid sample containing a plurality -3 - of particles into the first body of electrolyte and toward said aperture. 2°· 2i. A particle study device according to claim 20* 19 wherein said ejecting device includes means for mounting said ejecting device in a predetermined position relative to said aperture such that an outlet orifice of said ejecting means from which fluid sample is ejected is located closely adjacent said aperture and such that said outlet orifice is coaxial with said aperture. 21. A method for studying particles in a fluid sus- by means of the device claimed in any of the preceding claims pensio /including the steps of: ejecting a specific minute amount of a fluid sample containing particles into a flow stream leading to a sensing zone; sensing particles in said sensing zone; and producing a signal in response to each particle sensed. 21 22. 2Φς The method according to claim 2c¾, wherein said step of ejecting sample is accomplished by heating a thermal expansion device within a sample containing chamber, communicating with said flow stream via a small orifice, thereby to raise the temperature of said device to cause said device to expand and increase in volume to eject from said chamber a specific minute amount of fluid equal to the volume increase of said thermal expansion device. 21 or 22 23. 2Α¾ The method according to claim 2£x¾8?"09< including the steps of supplying electric energy to said thermal expansion device; monitoring the energy being supplied; and terminating the supplying of electric energy after a predetermined amount of electric energy has been supplied to said thermal expansion device. 23 24. 25.. The method according to claim 2$, wherein the step of monitoring the electric energy supplied includes the steps of: integrating the current supplied to the thermal expansion device from a constant voltage source; and comparing the voltage developed by said integrating with a given voltage, said termination of the supplying of electric energy occurring when said developed voltage equals said given voltage. 22 to 24 25306 The method according to any of claims $$*&$x $ including the initial step of filling said chamber. 25 26. 307>i The method according to claim ¾¾ wherein said step of filling said chamber consists essentially in sucking a quantity of a fluid sample containing particles into said chamber through said small orifice. 25 or 26 27 '· ¾B* The method according to claim ¾Φ"6*?«27, wherein said chamber is formed in a body having an opening larger than said small orifice communicating with said chamber, and said step of filling said chamber includes the step of introducing fluid sample containing particles through said opening into said chamber until said chamber is filled and the step of closing said opening. 28.X¾j A device for ejecting a specific minute amount fluid sample substantially as described in the foregoing specification and illustrated in the accompanying drawings 29.88* A method for studying particles in a fluid suspension substantially as described in the foregoing speci fication and illustrated in the accompanying drawings.