A STUDY OF KESPIRATION 231 



The rapidity of respiration depends very largely upon the 

 degree of activity of the animal. Earthworms and toads, 

 for example, are rather sluggish in their movements, and 

 therefore require a relatively small amount of oxygen. In 

 the warm-blooded birds and mammals, on the other hand, 

 metabolism goes on at a rapid pace, and new supplies of 

 oxygen must be hurried into the body to help keep up this 

 process. 



