24 SCIENCE PROGRESS 



a table given by Paul Bert {Lemons sur la Physiol. Comp. de la 

 Respiration, p. 393, Paris, 1870) : 



Rat 210 respirations per minute. 



Rabbit .... 55 „ „ „ 



Cat 24 „ „ „ 



These numbers quite bear out the contention that the faster- 

 breathing animals are the first to die. 



The rapidity of respiration is dependent on the rate of heat 

 loss, and consequently one would expect that small animals 

 which have a large surface for heat loss in comparison with 

 their bulk would breathe the faster, unless the larger proportion 

 of surface be compensated by the possession of thick fur, such, 

 for instance, as clothes the guinea-pig. Thus the writer would 

 suggest that animal idiosyncrasy is largely dependent on the rate 

 of heat loss, since that governs the rate of respirations. The very 

 steps that the rapid heat loser must take to procure an extra 

 amount of oxygen to maintain the temperature will also procure 

 for him an extra amount of chloroform in his blood. The young 

 are more rapid heat losers than the fully developed : the kitten, 

 therefore, is more quickly killed than the cat. The writer, apply- 

 ing these considerations, found that a concentration of 1 per 

 cent, of chloroform was quite sufficient to induce anaesthesia in a 

 young child, whilst 07 per cent, was sufficient to maintain 

 narcosis. These figures are only about half the magnitude of 

 those commonly accepted in regard to adults. 



It might be well here to give a list of the factors which 

 influence the rate of absorption of chloroform, and accordingly 

 its concentration in the lymph. 



(1) Rate of respirations. 



(2) Depth of respirations. 



(3) Relation of depth of respirations to bulk of supple- 



mental and residual air. 



(4) Rate of blood stream through the lungs. 



When we consider this list we see how careful we should be 

 not to declare any case to be one of idiosyncrasy until we have 

 assured ourselves that it is not one of the above factors which is 

 in reality the cause. The writer believes that the vast majority op 

 cases of so-called idiosyncrasy arc as a matter of fact to be explained 

 by variations in one of the factors which influence the rate of 

 absorption. 



