CORNER 



PLATE 1 





r 





Embryonic shield 



.e^e*' 

 a.* 



J.F.Didusch fecit 



A.Hoen& Co imp 



(2) Section illustrating structure of a normal 7-day pig ovum. This is the same specimen shown in text-figure 1 a. X 600 ; i. c. m., 

 inner cell mass. (3) Section of abnormal ovum shown in figure 1 b, illustrating flattening of the vesicle with partial degeneration of its 

 cells. X 600. (4) Section of a degenerating flattened embryonic vesicle of about the 7th or 8th day. X 600. (5) Section through 

 normal blastodermic vesicle of the 1 1th day. X 150. (6) Section through tumor mass in wall of early blastodermic vesicle, showing 

 irregular growth of embryonic cells. X 150. Drawings made directly on stone. 



