LOW TEMPERATURE — DEVELOPMENT OF FUNDULUS 465 



We should recognize, as preliminary to much of the discussion 

 that follows, that either the morphological or the chemical ex- 

 tent of the initial disturbances may not be the only condition 

 correlated with the extent of the later derangements. A com- 

 paratively slight modification in an essential or highly impor- 

 tant organizational factor would have a more marked result in 

 later development, than would a more extensive alteration in 

 factors of lesser importance. The quality of the disturbance 

 rather than its extent is primarily involved. It is further likely 

 that no relation could be determined between the extent of the 

 initial disturbance and the final effect on account of the possi- 

 bihty of regulatory action and because comparatively slight 

 initial alterations might give a wholly abnormal trend to a long 

 series of consequent processes finally resulting in very pro- 

 nounced abnormalities. 



With this general statement of the essential nature of the 

 disorganization hypothesis we may turn to an examination of 

 the widely current nutrition hypothesis, based largely upon the 

 results following chemical treatment, in order to draw attention 

 to certain difficulties in its appUcation to some of the observed 

 facts and to inquire whether the suggestions made here avoid 

 any of these difficulties without creating others. 



If any justification seems necessary for the attempt to criti- 

 cize, from the viewpoint of the results of the action of low tem- 

 peratures, the hypothesis based upon chemically prod ced 

 effects, it is to be found in the essential identity of the conse- 

 quences of these different modes of treatment. Indeed I should 

 go further and bring under this same point of view the abnor- 

 mal types of development following certain other experimental 

 conditions, such as heterogeneous hybridization, and the sub- 

 jection of gametes or zygote to radium radiations, which will be 

 discussed later. 

 The nutrition hypothesis as stated by Mall, and to some extent 

 adopted by Stockard, has for some time now largely been held 

 to account for such illustrations of teratogenesis as those de- 

 scribed here, but it seems open to certain serious objections. 

 In the first place it might be pointed out that the work of Pack- 



