194 STOCKARD— CONTROL OF DEVELOPMENT. [Apni >9. 



evaporating 95 per cent, alcohol enough of the fumes penetrate the 

 shell and enter the contents of the egg to cause the developing 

 chick to form abnormally. 



McClendon has lately found that an excess of CO2 and other 

 substances also cause cyclopia and brain abnormalities. Many 

 other workers have shown the effects of the environment on the 

 developing egg. 



It is, therefore, proven that the experimenter has the power to 

 take an egg which would normally give rise to a perfect animal and 

 by proper treatment he may cause it to form a typically abnormal 

 individual. The monster may in many cases be able to survive and 

 move about. No one can question that in these experiments the 

 vmfavorable environment modifies the form of the resulting indi- 

 vidual. 



Does this also occur in embryos developing in the mother's body? 

 Children are born which exhibit the same types of deformities as 

 those described above. Syphilitic mothers usually abort or give 

 birth to abnormal children and there is much evidence to indicate 

 that an alcoholic mother is more apt to produce an abnormal child 

 than is a non-alcoholic mother. 



Tubal pregnancies are common among women with venereal dis- 

 eases and in such cases the embryo must necessarily develop under 

 abnormal environment, having a poor surface for placental attach- 

 ment in a region not adapted to the conditions of pregnancy. The 

 conditions for embryonic nutrition are poor. Mall has found that 

 while only 7 per cent, of uterine pregnancies in his records con- 

 tained pathological embryos, that 96 per cent, of the embryos in 

 tubal pregnancies were pathological, only 2 in 46 specimens being 

 normal. This is strongly indicative of an abnormal environment as 

 the cause of abnormalities. If these monsters were due to inherent 

 tendencies in the germ cells one should not expect more abnormal 

 tubal than uterine embryos. 



Among lower mammals it has been shown that dogs fed on 

 alcohol produce deformed and otherwise defective pups. I am now 

 conducting a series of experiments with guinea pigs which show 

 that a female treated with alcohol during her pregnancy will often 



