70 FRANKLIN P. MALL 



observed in swine and other animals without any indication of 

 an inflammatory environment. For this reason I have sought 

 the primary factor in a condition buried in the non-committal 

 term fault}^ implantation. It would seem to be apparent that 

 lesions occurring in the chorion as the result of faulty implanta- 

 tion, can and must be reflected in the embryo. For example, 

 before circulation has developed, in a human embryo, pabulum 

 passes from the chorion to the embryo directly through the 

 exocoelom, and probably on this account we always encounter, 

 as a first indication of pathological development, a change in 

 the magma. In older specimens before any other changes are 

 noticeable in the ovum, the magma become markedly increased, 

 and a variety of changes are found between the villi. I shall 

 not dwell further upon magma as I have recently dealt with 

 the subject in detail.^ 



It is perfectly clear that monsters are not due to germinal 

 and hereditary causes, but are produced from normal embryos 

 by influences which are to be sought in their environment. 

 Consequently, if these influences are carried to the embryo by 

 means of fluids which reach it either before or after the circula- 

 tion has become established, it would not be very far amiss to 

 attribute these conditions to alterations in the nutrition of the 

 embryo. Probably it would be more nearly correct to state 

 that change in environment has affected the metabolism of 

 the egg. Kellicott, who has recently discussed this question, 

 seems to be disinclined to accept such an explanation, but I do 

 not see that he has added materially to it by substituting the 

 word disorganization for nutrition as one might as easily say 

 that the altered nutrition causes the disorganization. ^ 



In my paper on monsters I stated that on account of faulty 

 implantation of the chorion the nutrition of the embryo is af- 

 fected, so that, if the ovum is very young the entire embryo is 

 soon destroyed, leaving only the umbilical vesicle within the 



* Mall, Franklin P. On magma reticule in normal and in pathological de- 

 velopment. Contributions to Embryology, vol. 4, Publication No. 224, Carnegie 

 Institution of Washington, 1916. 



3 Kellicott, W. E. The effect of lower temperature upon the development of 

 Fundulus. Am. Jour. Anat., vol. 20, 1916. 



