550 E. I. WERBER 



tion, be recognized as a very rudimentary optic cup with an 

 imperfectly differentiated lens. The latter is (as can be made 

 out without difficulty even at the low magnification of the 

 figure) in a stage transitional between the cellular of the lens- 

 bud and fibrillar of the fully developed lens. In sections more 

 posteriorly, and beyond the level of this first isolated eye, the 

 second and larger one comes into view exactly opposite the 

 monophthalmic embryo's brain (fig. 83). Two small lenses are 

 first seen in this eye, the retina of which has an early embryonic, 

 rudimentary appearance. In more posterior sections, the smaller 

 of the two lenses disappears, while the larger one appears to be 

 of a size to fit the eye, in which at this level the retina appears 

 to be better differentiated, its rods-and-cones layer being clearly 

 discernible (fig. 84). In still further sections posterior to this 

 larger isolated eye there comes into view the highly malformed 

 brain fragment from which the eye has arisen. 



There is no connection whatsoever between these two isolated 

 eyes and the embryo. Like conditions obtain in the two other 

 eggs with isolated eyes (figs. 29 and 43) which have also been 

 examined in sections. 



No degeneration, as suggested by Loeb, can account for such 

 cases. For, there are no processes of degeneration to which the 

 already formed embryo might be subject other than (occasion- 

 ally) necrotic (cytolytic?) changes. The latter, however, lead 

 to the entire embryo's rapid death. 



These teratomata present one more striking proof for the cor- 

 rectness of the assumption that the injuries sustained by the 

 eggs, due to a noxious alteration of the environment, are of a 

 blastolytic nature. The 'isolated eye' as well as the 'soUtary 

 eye' develops from a fragment of the anterior end of the poten- 

 tial embryo's body. In the first case the remainder of the germ's 

 substance survives and develops into a teratophthalmic embryo, 

 while in the latter the fragment which eventually develops into 

 an eye is all that survives of the germ. These effects are due 

 mainly to two causes, namely to chemical alteration of the germ's 

 substance which is greatest at the anterior end of the future 

 embryo's body, and to increased osmotic (exosmotic) pressure 



