160 ANSWERS TO PRACTICAL QUESTIONS 



escape from the body by this avenue are hastened in their exit, 

 and the skin itself becomes soft and moist. 



43. How can ive best show our admiration and respect 

 for the human body ? 



By conscientiously observing all the laws of physical hy- 

 giene, as well as moral purity. 



44. IVTiy is the scar of a severe wound upon a negro 

 sometimes white ? 



Because the cells containing the pigment or coloring matter 

 were destroyed by the severity of the wound, and have not 

 been restored. 



99 ! What is the philosophy of the "change of 

 voice " in a boy ? 



Up to the age of fourteen or fifteen, there is little or no 

 difference in point of size between the larynx of a boy and 

 that of a girl ; but subsequently the former grows proportion- 

 ately larger, so that at last, in the adult male, the vibrating 

 parts or vocal cords are necessarily longer than in the female. 

 They are also undoubtedly thicker, perhaps even coarser in 

 structure. From all these circumstances the adult male voice 

 is stronger, louder, and of lower pitch than the weaker and 

 higher vocal range accomplished by the female larynx. 



The cause of the difference in quality of the voice, known 

 as its timbre, is not well known ; but it must undoubtedly be 

 dependent on physical, that is to say, structural peculiarities in 

 some part of the laryngeal apparatus. 



The production of the different notes within the compass of 

 any one individual depends upon alterations in the length and 

 state of tension of the vocal cords, and on their degree of prox- 

 imity or separation from one another. The higher notes require 

 the vocal cords to be comparatively shorter, tighter, and more 

 closely approximated together ; while the lower notes demand 

 opposite conditions. A high note, furthermore, implies greater 

 rapidity in the movement of the air through the glottis ; but 

 the quantity of air passing is larger during the production of a 

 low note. 



