EXPERIMENTAL FISH EMBRYOLOGY 



597 



VITAL-STAINING OF THE AREAS OF THE 

 PRESUMPTIVE NERVOUS SYSTEM OF FUNOULUS 



A, B, C, represent stages in the 



early development of a single embryo. 



First embryo - entire nervous area. 



Second embryo - spinal cord area. 



Third embryo - mid- and hind-brain areas. 



Fourth embryo - nervous contributions 



from either side of the embry- 

 onic axis. 



Fifth embryo - fore-brain and eyes from 



material anterior to the shield. 



VITAL-STAINIHG OF THE AREAS OF THE 

 PRESUMPTIVE MESODERM OF FUNOULUS 



Drawings A to D represent stages in 

 the development of a single embryo, 

 reading from left to right. 



Note that the mesoderm is derived 

 from the lateral wings of the embryonic 

 shield, from the germ ring, from the 

 germ ring 180° distant from the embry- 

 onic axis, and from the extra-embryonic 

 membrane. 



Successive stages In the development of embryos 

 in which the presumptive endoderm has been vitally 

 stained. When stain has been applied to the pos- 

 terior lip of the early embryonic shield (A), the 

 invagination of stained cells may be watched as 

 gastrulation proceeds (B) . Occasionally the stain 

 still remains localized in the region of Kupffer's 

 vesicle after the blastopore is closed (C) . 



(From Oppenhelmer I956: Jour. Exp. Zool. Ti'-hO^) 



