414 JAMES CRAWFORD WATT 



tendency to be hereditary than many other kinds. Adami ('08) 

 gives certain good examples of hereditary transmission of such 

 deformities. There is, however, in the case studied here no 

 evidence that heredity plays any part in the production of the 

 abnormality and the cause must be sought for elsewhere. 



Again it is possible for a monstrosity to be produced by defi- 

 ciency in either germ cell, which will produce a deficient ferti- 

 lized ovum. A normal fertilized ovum may also be injured and 

 Conklin ('05) has shown that even in the ovum there is. a differ- 

 entiation and specific localization of organ forming substances, 

 one of which could be damaged thus leading to the production' 

 of abnormal embryos and monstrosities. This has been done 

 by many workers, only one or two of whom, such as Werber 

 ('15) and Stockard ('09-10) need be mentioned. In this case, 

 however, damage to either of the germ cells and also to the 

 fertilized ovum is improbable as there is no history of either of 

 the parents suffering from venereal disease, alcoholism or drug 

 habits and neither of them work in noxious surroundings where 

 poisoning would be possible with lead, arsenic, phosphorus or 

 other agents. 



The period of the production of this deformity is thus excluded 

 from the germinal stage and must be either in the embryonic or 

 foetal stages. The foetal stage also can be excluded, for as 

 pointed out by Ballantyne ('04) in his excellent book on antena- 

 tal pathology, foetal physiology is, if not identical, at least simi- 

 lar and parallel to that of the individual after birth, and thus, 

 foetal pathology is mainly concerned with disease and disordered 

 metabohsm. On the other hand the embryonic period is a 

 period whose physiology is not that of functional activity of 

 organs, but of organ formation and differentiation. Pathologi- 

 cal conditions in the embryonic period, therefore, lead to mal- 

 formations and so if severe to the production of monsters. The 

 deformity in this case is thus limited in its production to a period 

 between the first and seventh weeks of intra uterine life. Dur- 

 ing this period the limb buds appear and bones and muscles 

 differentiate in them. 



