AND PHYSIOLOGY. 



151 



Muscular Fibrils of the Tig. a, An ap- 

 parently single fibril, b c, Collections of 

 fibrils. 



horse or cow during the time Fig. 162 - 



when flies irritate by biting. 

 The same muscle in the por- 

 cupine and armadillo is made 

 use of to roll themselves up in 

 a ball. In apes the foot and 

 hand are similar both in mus- 

 cular development and func- 

 tion, but are by no means 

 equal to the hand of man. 

 The abdominal muscles of all 

 quadrupeds are stronger than 

 man's, since from their posi- 

 tion the weight of the viscera 

 is thrown upon the muscular 

 walls of the abdomen, and 

 not upon the bones of the pelvis, as in him. In beasts of 

 prey the masseter and temporal muscles are more strongly 

 developed than in man, because great strength is required 

 in the jaw to secure the food and fit it for digestion. In all 

 mammals a more or less complete diaphragm is found, though 

 it is absent in nearly all the remaining vertebrata. 



281, Muscles of Birds — Ossification of Tendons. — The 

 muscles of most birds are remarkable for their deep red color 

 and the density of their structure. In herbivorous ones, how- 

 . ever, they are of a paler color and softer in texture, and hence 

 more palatable as articles of food. The bellies of the muscles 

 are for the most part situated on the body, so that they may 

 not encumber the limbs ; and those designed to move the ex- 

 tremities are extended into long tendons, which, as already 

 mentioned, become ossified to a considerable extent. 



Of what use is this muscle in the porcupine and armadillo? Why are the abdominal 

 muscles of quadrupeds proportionally stronger than in man? What is said of the strength 

 of the masseter and temporal muscles of beasts of prey? What of a diaphragm? 281. 

 What are the muscles of birds remarkable for ? What is said of the tendons and bellies 

 of muscles in birds ? 



