124 EXPERIMENTAL PHYSIOLOGY. 



accomplished by taking about 0.5 c.c. of the fluid in a glass tube 

 of sufficient external diameter to fit tightly the rubber tubing of 

 the receiver (a 1 c.c. pipette with the delivery end partially cut 

 off). Before inserting the pipette into the rubber tubing, the lumen 

 of the latter beyond the clip is filled with the anti-foaming solution, 

 so that no air may enter the receiver, and after inserting, the screw 

 clip (1) is very cautiously opened and about 0.1-0.2 c.c. of the solu- 

 tion allowed to run in, after which the clip is again screwed tight, 

 the pipette removed, and the solution still in it replaced in the 

 stock bottle. The receiver is reattached to the water pump and 

 evacuated as far as possible. 



It is then attached to tube D of the blood pump and evacuation 

 completed by manipulating the pump as described below for the 

 evacuation of blood. When completely evacuated, as judged by 

 the inability to suck over more air, screw clip 1 is closed and the 

 blood receiver removed from the pump. 



Ten c.c. of blood is now placed in the receiver. To accomplish 

 this, blood is removed from the flask by means of the special 10 c.c. 

 pipette, using only gentle suction and filling to the upper mark. 

 All air is squeezed out of the tubing on the blood bulb, and the 

 end of the pipette inserted in the tubing, being careful to see that 

 no air bubbles are present at the union. Holding the pipette and 

 blood bulb vertically, the clip is very cautiously unscrewed, and 

 the blood allowed to flow from the pipette into the bulb until the 

 lower mark on the former is reached. The capacity between the 

 two marks is 10 c.c. After tightening the screw clip, the pipette is 

 removed and the blood left in the tubing is squeezed out. 



The blood pump must now be prepared. 



This consists of a 50 c.c. all-glass (Luer) syringe (B), with vaseline between the 

 walls and piston, the nozzle being connected by thick-walled rubber tubing, /, 

 with the single tube of a three-way stopcock (C). Of the other tubes of the 

 stopcock, one (D) runs to connect, by narrow-bore glass tubing, with the blood 

 bulb and the other () to the gas burette (F) a 10 c.c. graduated pipette is satis- 

 factory. To avoid all risk of air leakage into the syringe, this is manipulated in an 

 o 1-bath (O) as shown in the figure. The barrel of the syringe is clasped at its 

 upper end by a brass collar (L) which is held by the iron rod (R) to the upright 

 (/). To the latter is also hinged the free ends of another iron rod bent on itself 

 (S), the bend being about 30 cm. from the free ends. Two strips of brass are 

 loosely attached to the two arms of the bent rod on either side of the syringe 

 where they cross it, and these run down to connect with the head of the piston of the 



