LOAV TEMPERATURE— DEVELOPMENT OF FUNDULUS 479 



tegratioiuil mcchanisni is or may be affected. Several obscure 

 relations noted by Newman might be profitably discussed from 

 the* viewpoint of the general hypothesis which I am suggesting, 

 for example, his statement (p. 469) that "It is difficult to imagine 

 what factors underlie this wide range of success of individual 

 hybrids of the same parentage," an explanation of which I think 

 these suggestions afford. 



However, it is not my intention, at this time, to attempt a 

 general application of this disorganizational hypothesis to such 

 phenomena, and the work of Moenkhaus and Newman is men- 

 tioned in this connection chiefly to show that such observations 

 are not counter to this general explanation of the causes of 

 abnormal development. For it is, I take it, a strong point in 

 favor of any suggested cause of a restricted group of phenojnena, 

 that it is not opposed by the facts concerning nearly related 

 phenomena. Such seems to be the case with these suggestions 

 as to the causes underljdng the formation of abnormal and mon- 

 strous embryos in Fundulus; for it not only accounts for the 

 results following treatment with low temperatures and chemical 

 substances, but it is not opposed, to say the least, by observa- 

 tions on the causes of similar developmental phenomena follow- 

 ing treatment of the germ cells by radium radiations and fol- 

 lo^ving hybridization, and further, it accords with what is known 

 of the early development (cleavage) of the Teleost and with the 

 current general conceptions of the developmental process. 



SUMiMARY 



1. By subjecting the eggs of Fundulus, immediately after 

 fertilization, to the temperatures of the ordinary refrigerator, 

 many of them are caused to develop abnormally when returned 

 to the laboratory temperature. 



2. The abnormalities observed after such treatment cover a 

 verj' wide range and no characteristic, externally observable, 

 is found not to be affected to some degree in some embryo. 



3. Similar treatment after the embryo has become well-formed 

 also leads to similar results, though with lesser frequency. 



