No. 518] 



REGENERATION 



103 



tastic ancestral condition. But quite apart from that, 

 the looseness of his argumentation is further increased 

 by the circumstance that anatomists are by no means 

 certain that the pineal body is an eye, and judging by the 

 structure of its lens it may also be a heat-perceiving 

 organ, as some indeed have suggested. 



Thus far I have been considering what might properly 

 be called the preliminary steps leading to the hypothesis, 

 that the end result of regeneration differing from the 

 usual result of ontogenetic development lends the key to 

 a solution of obscure morphologic problems. This sug- 

 gestion or idea is at the bottom of Davydoff 's entire 

 work ; it persistently crops up here and there throughout 

 the monograph. In short, it is the soul of that work. 



From what has been said in the foregoing it ought to 

 be clear that if the hypothesis of the repetition of ontog- 

 eny in regeneration, and also that of the atavistic na- 

 ture of the deviations from the normal condition, are not 

 false assumptions, they are at least deserving the verdict 

 "not proven." Since in no known system of logic does 

 the truth issue from propositions, either wholly untrue 

 or else of such uncertain veracity as to leave free choice 

 to intellectual likes and dislikes, it would seem that 

 Davydoff was laboring largely under a mistaken prin- 

 ciple. 



I am, however, ready to go to the extent of granting, 

 just for the sake of further argument, that the first two 

 propositions are demonstrably true, and that conse- 

 quently Davydoff 's idea of using regenerated peculiari- 

 ties for the purpose of solving obscure problems of 

 phylogenetic importance is, humanly speaking, beyond 

 objection. A moment's consideration will not fail to con- 

 vince us that even though truth may be a quality of 

 Davydoff 's principle, its function could be either of 

 purely negative value or even of no value. 



The literature on regeneration abounds in instances 

 of departures from the normal which appear either 

 sporadically or even regularly in the course of regenera- 



