ANATOMY OF A MONODACTYLOUS FOETUS 415 



Schwalbe ('Oo) has pointed out that there is a definite termi- 

 nation period for the production of any deformity. Before the 

 end of this period practically all deformities of that particular 

 type must appear, and any produced later than this are to be 

 regarded in the light of accidental occurrences injuring originally 

 perfect parts and so simulating abnormalities produced as errors 

 of development before this termination period. The termina- 

 tion period in each case marks that special time in which organo- 

 genesis ceases and functional activity begins in any particular 

 organ or part and marks the limit in time beyond which a given 

 deformity rarely if ever has its origin. This reckoning also 

 places the latest period for the production of the limb deformity 

 in this case at the seventh or eighth week, when the limb is fully 

 differentiated and ossification in the limb skeleton begins. 



Mall ('08) after a critical study of one hundred and sixty-three 

 pathological embryos, has concluded that most monsters are 

 produced by the faulty development of normal ova due to ex- 

 ternal influences, usually a vice of nutrition due to faulty im- 

 plantation which in turn is generally due to an abnormal condi- 

 tion of the uterine mucosa. Such a condition for instance would 

 be a mild, chronic endometritis which would not prevent the 

 occurrence of a pregnancy but would be enough to catise faulty 

 development. This might well be the cause here, as there is in 

 this case a history of two miscarriages previous to the birth of 

 this monster, without any apparent toxic agent or disease lead- 

 ing to their production, thus giving presumptive evidence of an 

 abnormal condition of the uterus, which would cause faulty 

 implantation and eventual death and expulsion of the products 

 of conception. 



Mall has estimated from statistics from various sources that 

 in 100,000 pregnancies there are 80,572 normal births, 11,765 

 abortions of normal embryos, 7048 abortions of abnormal em- 

 bryos and early monsters, and 615 monsters born at term. In 

 view of the great prevalence of uterine disorders, superadded to 

 the unsuitable conditions in which many pregnancies occur, the 

 pathological development of approximately 7.5 per cent does 

 not appear unduly high. It will be noted that one monster is 



