I9I2-] STOCKARD— CONTROL OF DEVELOPMENT. 199 



These results stand in marked contrast to the records of the 

 control, which show all normal conceptions and normal offspring. 



The second table shows the results of successive matings in ten 

 of the females. The varying success of the conceptions in the same 

 individual are striking. 



Nice has quite recently recorded a similar series of experiments 

 with alcohol on mice. Alcohol was given to the mice in their food. 

 Nice finds that while there was a certain fatality among the offspring 

 from alcoholic parents as compared with those from normal parents, 

 where there was no fatality, yet nevertheless the offspring of alco- 

 holic parents actually grew faster than those from the control. This 

 may indicate that alcohol is not equally poisonous in its effects upon 

 all animals, as might really be expected. The germ cells of mice 

 may be more or less immune to the action of alcohol. It is well 

 known that the action of alcohol is different in its effects on indi- 

 viduals from different human families. Some alcoholics show 

 chiefly nervous disorders, hallucinations, delirium, etc., while others 

 may have no nervous symptoms but exhibit various derangements 

 of the digestive glands, kidneys, etc., or may have a fatty degenera- 

 tion of almost all organs. 



Finally it may be concluded that the experimental evidence goes 

 to show that the development of an offspring may be modified by 

 either treating the parents so as to affect their germ cells or by 

 subjecting the developing embryo itself to unusual or injurious 

 conditions. 



The causes of many congenital defects are therefore known. It 

 is possible to control embryonic development to such an extent as 

 to produce abnormal structures. May not the proposition be re- 

 versed and unfavorable environments be treated in such a manner 

 as to render them favorable to normal development? Diseased 

 mothers may in some cases, at least, be made fit for the function 

 of reproduction. 



The regulation of structural disease becomes then a problem of 

 morphology and hygiene. It is most important, and must precede, 



