108 ADDITIONAL NOTES. 



ments having been made in a close vessel, the 

 cold air inspired must necessarily have been 

 always mixed with a certain portion of the air 

 expired previously, but also because, from the 

 relative position of the animal and the aperture 

 in the upright portion of the tube, the air drawn 

 into the latter by the elasticity of the gum-bottle, 

 and afterwards impelled into the lungs, must 

 have had communicated to it a large portion of 

 the heat which the entire body of the animal 

 was gradually losing. 



According to the then received theory of the 

 production of animal heat, the loss of heat in 

 these experiments cannot be accounted for, ex- 

 cept by assuming that there was a very much 

 smaller quantity of oxygen consumed, and of 

 carbonic acid generated, than where respiration 

 is performed under ordinary circumstances. 

 Such an assumption, however, even as to my 

 first series of experiments, is not supported by 

 the facts. The dark venous blood, after it had 

 passed through the lungs, underwent the usual 

 change of colour; and not only the contractions of 

 the heart were regularly performed, but, in dogs 

 especially, there seemed to be actually an increased 

 irritability of the voluntary muscles, continued, 

 not for a short time, but even for an hour and a 

 half, and until the temperature of the rectum 

 had fallen to 15 (Fahrenheit) below the na- 

 tural standard. These muscular contractions 

 were most remarkable, in one of the experiments 

 related in my first paper on poisons, after the 



