Figure 6. Table 1 illustration from Wolff's "On the Formation 

 of the Intestine . " 



1 . Vascular area (area vasculosa) from upper surface after 

 three days of incubation; a — vascular area; b — transparent 

 place (area pelludica) ; c — embryo; d — heart; e — lateral 

 yolk veins; f — descending vein; k — boundary vein. 



2. Lower surface of the vascular area and on it the vesicle 

 or false amnion; a — lower surface of the vascular area; 

 b — transparent place; c — false amnion and on it (from c 

 to d) cephalic branch; di — middle part of it; i to b — 

 caudal membrane; d — cardiac fossa, from d to i, commissure; 

 i — lower fossa; e — lateral veins; f — descending vein; 



g — ascending vein; h — boundary vein. 



3 . Upper surface of the vascular area in living embryo of three 

 and a half days of incubation; a — embryo; b — fossa, which 



it forms in yolk; c — origin of yolk veins; d — their lower 

 branches; f — middle branches; g — branching of the upper 

 branches; h — ascending vein; k — its branches; i — descending 

 vein; 1 — terminal vein. 



4. Vascular area in living condition; a — chamber of heart; 

 from above, bulb of aorta, from downwards, auricle of 

 the heart; b — aorta; c — hollow vein; d — ascending vein; 

 e — descending vein. 



5. Transparent place in the embryo from lower surface, 

 under microscope, 54 hours of incubation; a — transparent 

 place; b — cephalic branch; c — part of the embryo above 

 the cardiac fossa; d — anterior part of the head; 



e — heart; f — first rudiment of the true amnion; g — ascending 

 vein; h — origin of cephalic branch; i — swollen edge of the 

 ventricle opening; k — opening of the stomach still is not 

 closed, but has narrowed; 1 — abdominal folds; m — intestinal 

 folds; n — rudiments of vertebrae; o — end of vertebrae; 

 p — the beginning of formation of amnion opening; 

 q — spinal cord; r — marked lateral parts of the vesicle; 

 s — traces of retiform, derived from red blood, vessels; 

 v— -first rudiment of the caudal membrane. 



6. Part of lower surface of the vascular area with the 

 transparent place and embryo, after two days of incubation. 



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