ZOOLOGICAL POSITION OF MAN. 13 



centers run through both abdomen and chest, and extend 

 beyond the latter into the neck. 



The ventral cavity, opened from the front, but with its 

 contents undisturbed, is shown in figure 4 We there see 

 the edge of the diaphragm, 2, 2 ; above this, in the chest, 

 the lungs, lu, lu, and the heart, h ; the latter partly covered 

 by other things. Below the diaphragm is the abdominal 

 cavity, containing in its upper part the liver, le, le'\ the 

 stomach, ma ; and the spleen, mi\ hanging down like an 

 apron from the lower border of the stomach is the amen- 

 tum, ne, ne, which lies over and conceals the intestines. 



Summary. Man is a vertebrate animal, because his 

 body presents dorsal and ventral cavities separated from 

 one another by a hard partition ; the dorsal cavity con- 

 tains the brain and spinal cord, and reaches into the head; 

 the ventral cavity stops at the bottom of the neck and 

 contains the main organs of circulation, respiration, and 

 digestion. 



Man belongs to that subdivision of vertebrates known 

 as Mammalia (1) because more or less of his surface is 

 covered by hair ; (2) because of the presence of mammary 

 glands ; (3) because the ventral cavity is completely sep- 

 arated by the diaphragm into thorax and abdomen. 



That man is intellectually incomparably superior to 

 any other animal, and stands supreme in the world, can 



Name the parts seen when the front wall of a man's trunk is cut 

 away. Describe the relative positions of these parts. 



On what anatomical grounds do we call man a vertebrate animal? 

 What lies in the dorsal or neural cavity? How far does the upper end 

 of this cavity reach? What organs lie in the ventral cavity? Where 

 does its uppti^. limit lie? TV hy is man a Mammal? in what is man 

 superior to iy other animal? From what point of view have anato- 

 mists to regard man's body? What sort of facts do they take iii to 

 account in assigning man's position among animals? 



