242 ELEMENTS OF MAMMALIAN ANATOMY. 



The average weight of a male human brain is about 

 three pounds; of a female, about two and two-thirds 

 pounds. The human brain is -% the weight of the body; 

 the ape's, ^V; the rat's, -^ ; the sheep's, o4- T ; and the ele- 

 phant's, 5-^0 . The brain of man is larger than that of 

 any other mammal except the whale and elephant. The 

 brain of a large whale weighs over four pounds, while 

 that of a large elephant will weigh about ten pounds. 



PRACTICAL QUESTIONS AND SUGGESTIONS. 



1. How many nerves transmit the stimuli received by the organs of 

 special sense? 



2. Where are the sense organs of pain located ? 



3. How many sense organs are visible in the mesentery of your 

 specimen? 



4. Describe the path of a stimulus from the index finger to the brain. 



5. Through which nerve roots would the stimuli received by the 

 cutaneous sense organs pass into the cord? 



6. Describe the nerves transmitting the stimuli from the olfactory 

 organ. 



7. Describe the gland secreting the tears and how they reach the 

 nasal cavity. 



8. By cutting away the lateral and dorsal walls of the orbit dissect 

 the muscles of the eyeball and make a drawing of them, labeling all parts. 



9. What nerves control the movements of the eyeball? 



10. Procure the eyes of any mammal from the butcher-shop or slaughter- 

 house; bisect one in the meridional and the other in the equatorial direc- 

 tion. Make a drawing of the features seen and label. 



11. Remove the crystalline lens from a fresh eye, describe its size, 

 shape, structure, length of focus, and power of magnification. 



12. Describe the path of a stimulus from the retina to the area of 

 sight in the brain. 



13. Name every feature visible in the eyes you have dissected. 



14. What nerve supplies the auditory organ? 



15. Describe the middle ear. 



16. In what part of the temporal bone is the internal ear located? 



17. By looking into the auditorius meatus of the dried skull two open- 

 ings are seen. Into which portions of the internal ear do these lead? 



18. Write a description of the internal ear. 



19. Mention some important points of difference in the nervous system 

 of various mammals. 



20. What relation, if any, between intellectual ability and brain devel- 

 opment? 



