1891.] Quantity and Dynamics of Animal Tissues. 983 
weight of body to be supported is greater in the woodchuck, and 
since the quantity of muscle is relatively smaller, the animal is 
forced to a sedentary life and does not move about much. Even 
the forms of body in the two animals harmonize with this view. 
The woodchuck is stout and heavy, the rabbit is agile and slender. 
Just as the heavy bones of the woodchuck are indicative of its 
sluggish habits, so the light bones of the rabbit point to an 
opposite inference. Very much more could be said of the quan- 
tities and dynamical values of the animal tissues, but this must 
suffice at present. It is hoped that further evidence will be 
brought forward on some of the points here barely alluded to. 
The subject is certainly a very fruitful one for future research. 

