58 JACQUES LOEB. 



Figs. 7 and 8 illustrate the same fact, that a rather normal eye 

 with a lens was formed while later on only a very imperfect eye 

 remained. Fig. 7 shows the embryo when four days old with a 

 lens and an apparently normal eye, while five days later (Fig. 8) 

 no eye was perceptible. 



IV. 



BLIND FISH PRODUCED FROM PURE BREEDS OF FUNDULUS 



HETEROCLITUS. 



The writer was under the impression that the abnormalities in 

 the development of the heterogeneous hybrids in fish were due 

 to the influence of the foreign sperm as in the similar case of the 



FIG. 7. 



fertilization of the egg of the sea urchin with the sperm of the 

 star fish, where the mortality is also enormous. In order to 

 prove this assumption he tried to find a method which would 

 allow him to produce embryos with abnormal eyes in the pure 

 breeds of heteroclitus . He has already mentioned in a former 

 publication that such abnormal embryos were obtained when 



