24 TABOO AND GENETICS 



as well. It is due to the presence in the bodies 

 of higher animals of a considerable number of 

 glands, such as the thyroid in the throat and 

 the suprarenals just over the kidneys. These 

 pour secretions into the blood stream, deter- 

 mining its chemical quaUty and hence how it 

 will influence the growth or, when grown, the 

 stable structure of other organs and cells. They 

 are called endocrine glands or organs, and their 

 chemical contributions to the blood are known 

 as hormones. 



Sometimes those which do nothing but furnish 

 these secretions are spoken of as " ductless 

 glands," from their structure. The hormones 

 (endocrine or internal secretions) do not come 

 from the ductless glands alone — but the liver 

 and other glands contribute hormones to the 

 blood stream, in addition to their other functions. 

 Some authorities think that " every cell in the 

 body is an organ of internal secretion " (2), 

 and that thus each influences all the others. 

 The sex glands are especially important as 

 endocrine organs ; in fact the somatic cells are 

 organized around the germ cells, as pointed out 

 above. Hence the sex glands may be considered 

 as the keys or central factors in the two chemical 

 systems, the male and the female type. 



These various hormones or chemical con- 

 trollers in the blood interact in a nicely balanced 

 chemical system. Taken as a whole this is often 



