BIOLOGY AND PROGRESS 207 



active and that each sent out its chemical messen- 

 ger to speed on our normal development. On 

 the other hand, excessive activity of some of these 

 glands may cause serious results. The over- 

 activity of the pituitary body stimulates the body 

 to excessive growth and so we have an explana- 

 tion of gigantism in man. It is a pathological 

 product. Similarly lack of secretion in the pitui- 

 tary body results in obesity which is also a patho- 

 logical state. 



The little thought that is given to the sex glands 

 usually centers around their production of eggs 

 and sperms which is but one aspect of their regu- 

 lar activity for we now know that the cells which 

 do not grow into sex products, produce secretions 

 that pass into the blood and have an important 

 influence in shaping those general characters which 

 are distinctively male or female such as the 

 quality of the voice and the combination of quali- 

 ties which go to constitute a womanly woman and 

 a manly man. Experiments on rats, for example, 

 in which the ovaries were removed and testes 

 grafted into the body of the spaded female, re- 

 sulted in causing the female rat to take on male 

 qualities. When this experiment was reversed, 

 a similar change was produced in the male. Thus 

 indicating the very evident part which chemical 

 messengers as these secretions are termed play in 

 modifying the body. 



