582 



Experiments 



will form a hydraulic seal above the piston. Finally, on one of the 

 sides, a graduated rule shows the quantity of blood that has been 

 extracted. At the bottom of the syringe 

 is screwed in a connecting piece with a 

 cock, on which can be mounted tubes of 

 different forms. The total capacity is 

 from 80 to 100 cubic centimeters. 



Such a syringe, which I have described 

 in detail because it is the model on which 

 I fixed after many attempts, as being the 

 simplest, the most convenient, the strong- 

 est, and the least expensive, holds a 

 vacuum perfectly. However, through ex- 

 cess of precaution, I never used it without 

 introducing water above the piston, and 

 submerging the whole lower part in water 

 to a point above the end-piece; not a 

 bubble of air can then enter. 



A cannula being placed in the animal's 

 artery, part F is connected to it, and when 

 the serre-fine which closes the artery is 

 opened, the blood rushes into the syringe 

 with a pressure sufficient to raise the pis- 

 ton; I usually take 33 cubic centimeters for 

 each analysis. 



The blood extracted and held in the 

 syringe is immediately taken to the ap- 

 paratus for the extraction of gases. The 

 most important part of this consists of the 

 mercury pump whose description has been 

 given above. 



To the lateral tube, which I advise 

 should be placed obliquely, as Figure 24 

 shows, is fastened, by means of a rubber 

 tube with thick walls, a large glass tube 

 about 75 centimeters long, whose lower 

 extremity fits very tightly in the neck of 

 a tubular balloon D, whose capacity is 

 about 1 liter. From the tubulation of 

 this balloon extends a glass tube of very small caliber, twice bent, 

 whose end is closed by a cock r. 



Fig. 23 — Graduated sy- 

 ringe for extracting 

 blood. 



