59"+ 



EXPERIMENTAL FISH EMBRYOLOGY 



Semi-diagrammatic sketches of preserved Fundulus embryos to show the com- 

 parative stages of organ formation. Made with the assistance of a camera- 

 luclda. 



1. Twenty-eight hour old embryo in which the embryonic shield is differen- 



tiating and invagination has begun. 



2. Thlrty-six-hour-old embryo in which the embryonic axis has beguii to be 



recognizable . 



3. Forty-eight-hour-old embryo, Just before the formation of the somites. 



4. Ten-somite embryo. Note the beginning of the optic cups and auditory 



structures . 



5. Fifteen-somite embryo. Considerable change has occurred in the organiza- 



tion of the brain and sense organs. 



6. Twenty-five somite embryo, eighty hours of age. Note the increase in 



size as well as the degree of differentiation. 

 Ctiraera-lucida drawings of sections through the optic vesicles of Fundulus 

 embryos . 



7. Kmbryo in one-somite stage. 



8. Embryo in seven-somite stage. 



9. Embryo In ten-somite stage. Note the flattened optic vesicles and lens 



anlagen. 



10. Embryo in fifteen-somite stage. The optic cups are nearly complete and 



the lenses are developing. 



11. Embryo in twenty-f Ive-somlte stage. The lenses are completely separated 



from the ectoderm. 



( From Jones 1959-" Trans. Am. Microscopical Soc. 58:1) 



