The further description of behavior of the lower layer, 

 i.e. endoderm, is extremely important because it makes clear 

 that Wolff truly saw the initial stages of formation of the 

 digestive canal. This lower membrane of the vascular area, 

 Wolff wrote, "ascending and forming the vesicle which was 

 described by me, is considered that membrane from which the 

 intestinal canal is formed. How it takes place, how it is 

 generally possible that from the simple membrane a canal is 

 formed, will be explained later on." This description makes 

 up the contents of the second part of the work discussed. 



In this zone, which Wolff called the false amnion and 

 described in the form of a closed vesicle, first of all a 

 fossa is formed, situated at the level of heart. Wolff called 

 this fossa, because of its location, the cardiac fossa. 6 The 

 form of this fossa is nearly oval. Upwards and laterally it 

 is rounded and wider, downwards it is gradually compressed, 

 and later it passes downwards into the amnion commissure. To 

 this description Wolff added an explanation that here upper 

 and lower mean correspondingly anterior and posterior ends 

 of the embryo. 



This cardiac fossa, or cardiac opening, is the first 

 rudiment of the stomach. The result of the process 

 shows this exactly. The vesicle is subsequently 

 changed in this way: its part which forms the fossa 

 is transformed into the stomach . . . Which parts 

 of the stomach in this condition are already present, 

 which parts are still absent . . . can then be 

 explained in this way, that from here it is easy 

 to receive clearer proof of epigenesis . 



This general conclusion is supported by the following 

 interesting argument. 



From here it is clear without doubt that it does not 

 occur in nature that parts of the organized bodies 

 exist from the beginning, infinitely small and 



6. Meckel in his translation called it "gastric fossa" 

 which maybe represents its role in development, but 

 all this also may be unexactness of translation. 



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