368 



Drs. J. W. Pickering and J. A. Hewitt. 



following the injection of the " peptone " five samples of blood coagulated 

 rapidly. 



The common feature of these experiments is the great length of time 

 during which the animals were under anaesthesia, leading to a decrease of 

 oxygen (Buekmaster and Gardner, 8) and a corresponding increase of carbon 

 dioxide in the blood. 



Prior to the work of H^don and Delezenne (loc. cit.), Lahousse (9) had 

 shown that in peptone blood there is an extreme diminution of carbon dioxide, 

 while Fano (10) and Wooldridge (11) had demonstrated that the passage of 

 carbon dioxide through peptone plasma induces coagulation. Wright (12) 

 has also shown that an increase of carbon dioxide in normal circulating blood 

 augments its coagulability. 



The following experiments* show that the retarded coagulability of peptone 

 blood in animals intact, except for pithing, or in animals in which the liver is 

 not acting, may be diminished or annulled by excess of carbon dioxide ; the 

 general result is that when the vitality of the animal is impaired this 

 inevitably occurs with both moderate and larger doses of peptone. 



In these and the subsequent experiments all animals were anaesthetised 

 with A.C.E., pithed, and (except in Nos. 14-17) the anaesthetic was dis- 

 continued for at least a quarter of an hour before observations were made on 

 the blood. All blood was withdrawn through evenly paraffined cannulae. 

 Artificial respiration (except in Nos. 14-17) was employed throughout. The 

 animals were kept warm. The "commencement" of clotting was taken to be 

 when the first change towards coagulation was observed ; " completion " of 

 clotting when the vessel containing the blood could be inverted without 

 spilling. All glass vessels were cleaned with hot hydrochloric acid, caustic 

 soda, alcohol and ether. Dust was as far as possible excluded. The percent- 

 ages of " peptone " are necessarily approximate, since commercial specimens, 

 as used by different investigators, vary enormously in composition. In the 

 present work one preparation was employed throughout. 



The results obtained in Experiments 1, 2 and 3 are expressed graphically. 

 The points on the upper graph indicate " completion " of clot, those on the 

 lower graph " commencement " of clot. 



* Cats have been used in the experiments now recorded because their susceptibility to 

 " peptone " lies midway between that of the dog, which is markedly susceptible, and the 

 rabbit which is exceptionally resistant. 



