192 STOCKARD— CONTROL OF DEVELOPMENT. [April 19, 



out their lives. We carefully study and use all known precautions 

 to protect ourselves against post-natal infections and diseases, and 

 much interest and time is given to combating the causes, yet little 

 is said and scarcely anything done towards a control of development, 

 or the hygienic protection of the developing individual. 



This is really a morphological problem and is as truly a part of 

 the fight against disease as is the treatment of abnormal physiological 

 processes. It is not all of morphology to describe and study the 

 detail of bodily structure, but its important task is to understand 

 and analyze that structure, and if possible control and regulate its 

 formation: and thus, if properly developed its goal is to relieve the 

 race of its great structural disease — a disease which affects more 

 individuals than any other one malady of man. 



To m6st persons the above task seems at first thought a futile 

 undertaking, and any one suggesting such control or preventive 

 treatment might be interpreted as indulging in fanciful speculation. 

 Yet the data available from the studies of defective persons in 

 different countries of the world, and the experimental evidence fur- 

 nished by work on lower animals makes the correction or preven- 

 tion of developmental defects seem even today a problem to be 

 practically handled to a slight degree at least. 



To proceed as with any other disease, we must first ascertain 

 the cause of these conditions, as the possibility of a cure depends 

 upon the nature of the cause. 



Are monstrosities and defective development due to some innate 

 change within the germ cells of the parent, thus being incurable, as 

 many former workers would have us believe? Or, are they due to 

 changes produced in the germ cells by the action of some unusual 

 condition in the body of either the male or female parent, or finally 

 may they not be due to an unusual environment acting upon the de- 

 veloping embryo itself? In both of the latter cases the conditions 

 are open to regulation or control. These questions may only be solved 

 experimentally and the experiments have proven that the great ma- 

 jority of monsters are due to the action of unusual conditions upon 

 either the parental germ cells or the developing embryo. There may be 

 some changes of form or variations in animals which are due to 



