ON EPIGNATHUS lO 



Thus in their attachment the epignathi point to the first settlement of 

 their germ having taken place in the stomodaeum. 



III.— ON THE ORIGIN OF THE EPIGNATHI. 



In looking for the cause of the disturbance of normal development 

 which produces an epignathus, there is little suggestive in the aetiology. 

 Out of the twenty-two cases noted, the mother was a primipara in three, 

 and a multipara in nineteen. There is no evidence of any association 

 with previous twins or malformed foetuses, or of any hereditary tendency. 

 In several of the cases, as in that now recorded, there is a history of the 

 mother having received a severe nervous shock early in pregnancy. 

 Hydramnios is a frequently associated condition, but this may be more 

 an effect than a cause. 



In the discussion of theories which relate to the origin of the 

 epignathi, we find that two views have been advanced as to its 

 development. 



According to one view, epignathus is a single malformation — that is, 

 arises from the body of the fcetus. 



The generally accepted view, however, is that epignathus is to be 

 looked on as a double malformation — the two components being 

 asymmetrical, the one (autosite) being practically normal, and the other 

 (parasite) incomplete and attached to the first. 



Thus Ahlfeld holds the view that an epignathus is derived from a 

 second fcetus, even although there are no evident foetal parts — that is, he 

 regards it as a double malformation. His theory is that there are two 

 embryonic areas, one in front of the other, that one embryo lags in 

 development and comes to lie under the forebrain vesicle of the other 

 and eventually in the stomodaeum, its allantois becoming fixed to the 

 mouth and hence acardiacus. He postulates two unequal embryonic 

 areas with their heads towards each other. 



Arnold, in discussing the question of the origin of these tumours, 

 divides them into two groups. " Autochthonous " teratomata, such as 

 the hairy pharyngeal polypi, he traces back to the abnormal development 

 of a " dislocation " of embryonic material in the mouth or pharyngeal 

 cavities — that is, they are derived from one embryo. The " heteroch- 



(193) O 



