to 



II 



12 



13 



14 



15 



16 



Figure 31. Baer's illustration of "Transformation of the ovum 



of amphibia" 



1- First division; 2- second division; 3- third division; 

 4- typical fourth division; 5- atypical fourth division; 

 6- stage of blackberry; 7- stage of raspberry; 8- stage of 

 leathery surface; 9- stage of sandy surface; 10- section in 

 first meridional fissure, the rudimentary orifice with its 

 canal is seen; x- the remaining place of union of the hemi- 

 sphere of the ovum; 11 and 12- formation of second meridional 

 fissure; 13- vertical section after third division; 



14- vertical section through ovum in blackberry stage; 



15- section through ovum in stage of leathery surface; 



16- the same also in stage of the sandy surface. 



425 



