Figures 8-10. Illustrations of Wolff's work "Single egg 

 carrying twins." 



8. Egg extracted from the shell; a — albumin; b— yolk; 



c — the part of the terminal vein; d — the part of the yolk 

 which is devoid of vessels; e — area vasculosa; f , g— — upper 

 and lower embryo; h — the part of the umbilical vesicle of 

 the upper embryo; i — a depression in the yolk which is 

 produced by this vesicle; k, m — umbilical vesicle of the 

 upper and lower embryos; n, o — folds of the yolk membrane; 

 P/ <lr r — yolk vessels of the upper embryo; t, u, v— the 

 same vessels of the lower embryo . 



9. The part of the membrane adjacent to the embryo, from the 

 internal aspects; a — border of the cut membranes; b, c — 

 upper and lower embryos ; d , e — folds of the membranes ; 



f, o — openings of the intestinal canal of the upper and 

 lower embryos; p, q — border of the abdominal umbilical 

 opening which is transparent throughout the membranes; 

 h, i, k, m, n— — yolk vessels of the upper embryo; r — same 

 vessels of the lower embryo. 



10. Internal surface of the external membranes which is seen 

 after being separated and turned internally; a — external 

 yolk membrane; b, c — lower and upper embryos; d, e — part 

 of the internal membrane which extends into the intestines 

 of both embryos; f, g — their umbilical bladders; h — 

 opening of the umbilicus through which the internal yolk 

 membrane, which is a continuation of the intestine, leads 

 out from the abdomen; k— vessels; 1, m — folds of the 

 membranes . 



95 



