Figure 3. Table of drawings from K. F. Wolff's dissertation 

 illustrating the development of the chicken. 



1 . The embryonic spot (n) from the non-incubated egg in its 

 natural size? b, c — circular position of the globules 

 around the "center of conception" of the embryo (a) ; 

 d— granules of yolk. 



2. The embryonic spot after 28 hours of incubation in its 

 natural size. 



3. The same, under magnification? a — yolk membrane; 

 b — embryo, included in saccule of water membrane. 



4. The same, under somewhat less magnification; saccule (c) 

 on the embryo extends and the last shines (e) ; a and b 

 in correct rings and islets around the embryo; 



s — stretched membrane in fold. 



5. The embryo at 36 hours; in the head "something of a beak," 

 parts of brain and eyes with optic nerves; h — the spinal 

 cord; d, e, f, g — vertebrae; c — substance surrounding 



the spinal cord; b— cavity of embryo membrane; k — heart. 



6 . Part of the vertebrae of the embryo represented in 

 Figure 5, under greater magnification. 



7. The embryonic spot in the ovum after 64 hours of incubation, 

 in its natural size; v — yolk; d, f — islets: a — umbilical 

 disc; b — rudiments of the vessels; n — mobile particle 

 ("membrane" of Malpighi) ; e — embryo. 



8. Region of embryonic spot of the previous embryo, in 

 greater magnification; a — island of "white matter"; 



e, b — red fluid; d — boundary of the islet, as in Figure 7. 



9. Part of the spinal column (a) and heart (c) of embryo of 



64 hours; b — substance surrounding the vertebrae; d — cavity 

 of the heart with blood globules . 



10. Part of umbilical area after 72 hours of incubation; 

 magnification larger than Figures 7 and 8; e, fc> — ducts, 

 forming the vessels; m — boundary of the yolk. 



59 



