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H. H. NEWMAN. 



head and small or rudimentary body are the result of differential 

 acclimation. After all, the results of acclimation and recovery 

 even in controlled chemical experiments are so nearly identical 

 that, were it not for the differences in experimental method used, 

 they would be indistinguishable. 



On the whole then we can distinguish clearly only the two types 

 of monsters : 



(a) Forms with inhibited apical parts and relatively well 

 developed basal parts the results of differential inhibition. 



(&) Forms with inhibited basal parts and relatively well 

 developed apical parts the results of differential acclimation 

 or recovery. 



None of the forms of fish hybrids with which I am acquainted 

 fail to fall into one of these two categories and to receive a logical 



explanation on the basis of the axial gradient theory. It is my 

 belief that this theory offers the best explanation of teratological 

 development in fish and in all other axiate forms, including man. 



As a concrete illustration of the application of the theory to a 

 single experiment, I shall offer the details of an intensively 

 studied hybridization experiment, the one referred to earlier 

 in the paper in which the three lots of hybrid eggs were separated 

 on the basis of the rate of early cleavage into three lots A, B 

 and C. This experiment dealt with hybrids of Fundulus hetero- 

 clitus 9 X Scomber scombrus (mackerel) cT . 



Figs. 1-4 show types of teratomata in lot A. These embryos 

 are frequently almost normal up to an advanced stage and a 



