116 G. CARL HUBER 



the abnormal stages met with seems warranted, especially in 

 view of the fact that the literature is very meager in its ac- 

 count of early stages of mammalian ova presenting abnormal 

 development. 



The excellent and comprehensive studies of Mall on pathologic 

 human ova, extending over many years, may be interpreted as 

 leading to the general conclusion that pathologic ova and mon- 

 sters "are produced from normal eggs by conditions which either 

 interfere with their nutrition or poison them." There is evi- 

 dence to show that defective implantation, using the term in its 

 broadest sense so as to include relation to the embryotroph or 

 pabulum, is directly associated with abnormal development. 

 Comparative experimental teratology so successfully followed by 

 a number of European and American experimental embryolo- 

 gists warrants the conclusion that all of the abnormalities or 

 malformations observed in the human embryo may be brought 

 forth by the application of suitable mechanical interference or 

 chemical solutions. Experimental teratology possesses the very 

 great advantage of enabling the observer to follow the pathologic 

 process from step to step, admitting more readily of their inter- 

 pretation, than when single stages are obtained from nature. 

 The evidence appears to be accumulating that the primary causes 

 which produce pathologic ova lie not in the germ cells, but are 

 rather to be sought in the environs of the germ cells in the course 

 of their development. 



I am cognizant of the fact that the interpretation of the chance 

 findings of abnormal stages of mammalian ova is much more 

 difficult than of abnormal ova produced experimentally. The 

 fact, however, that nearly all of the abnormal ova observed by 

 me in my albino rat material were found in tubes and uteri con- 

 taining normal ova also, tubes and uteri which so far as observ- 

 able appear in most instances to be normal, and the further fact 

 1 hat certain of the abnormal ova are of stages prior to what may 

 be regarded as showing implantation, stages concerning which 

 we possess no data as far as human ova are concerned, has lead 

 to the tentative conclusion that certain of the abnormal ova 

 may be the resultant of abnormal germ cells, perhaps of an 

 abnormality which may not show a structural expression. 



