ZOOLOGY AND HUMAN WTILFARE 



readily available and the effects thoroughly understood, 

 birth control will become not only sure and easy, but also 

 biologically sound in the sense that ovulation and menstru- 

 ation will be started and stopped by the natural agency — 

 but at such times as seem desirable to the persons concerned. 

 Contraception is already well-nigh universal in spite of 

 the imperfection of the commonly known methods; and 

 endocrine zoology promises to make it safe and certain. 

 If and when this happens, the dwindling forces of opposi- 

 tion may as well abandon the struggle and contribute 

 their enthusiasm and altruism to the important task of 

 seeing that reproduction is reduced and regulated in such 

 manner as to benefit all concerned. 



The most recent accomplishment in endocrinology is the 

 preparation by Swingle and Pfiffner of an active extract of 

 the adrenal cortex, distinct and free from adrenalin. This 

 extract will keep alive cats whose adrenal glands have 

 been removed and which would die at once without the 

 artificially injected hormone. At the Mayo Clinic this 

 extract has been successfully used in advanced cases of 

 Addison's disease, restoring patients from a state of 

 complete collapse to activity and "the appearance of perfect 

 health." Thus another fatal disease is brought under 

 control, as was diabetes a few years ago. 



What has been said about the new zoological technique 

 applies also to cancer research. Abnormal growths can 

 now be transplanted from one mouse to another and other- 

 wise studied more closely than has been possible in the 

 past. One striking discovery that has been made in this 

 work shows that certain cancers and tumors, when trans- 

 planted, will grow only in animals that belong to certain 

 hereditary strains. If the mouse has a different hereditary 

 constitution, the transplanted tissue will simply disappear. 

 It is easy to see that such facts have a direct bearing on the 

 whole question of constitutional susceptibility to disease, 



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