598 



Experiments 



I then had another cannula made, all of metal, formed of two 

 pieces joined at b, of which Figure B gives a sufficient idea. I still 

 had difficulties, and finally developed an arrangement pictured in 



Fig. 29 — Different forms of cannulae A, B, C, and of serres-fines D, E, 

 for extracting blood under decreased pressure. 



C which gave me excellent results, and which, as often happens, 

 is the simplest of all. 



The experiment is performed in the following manner: After 

 the animal's carotid has been exposed and litigated at its upper 

 extremity, I hook upon the walls of one of .the compartments of the 



