ON A GENERAL THEORY OF ADAPTATION AND 



SELECTION. 



BY 



HENRY EDWARD CRAMPTON, Ph.D. 



It is the purpose of the present brief article to state in general 

 and non-mathematical form some of the results of statistical and 

 experimental studies, dealing with lepidoptera, that have been in 

 progress for nearly six years, and in the second place to develop 

 on the foundation of these results a generalized conception of 

 natural selection and its actual basis during the segregation ot the 

 fit or adapted and the unfit or unadapted individuals of a species. 

 I am led to offer this statement in this form and at this time 

 because many months must elapse before the statistical results of 

 recent studies may be put in final form for publication, though 

 the more general conclusions to be drawn from them may be stated 

 in simple terms; and it is my desire, furthermore, to present the 

 theory so that it may bear the scrutiny of the numerous investi- 

 gators now at work upon the problems of variation and selection, 

 in order that its validity may be tested in connection with different 

 kinds of biological material. In a word, this paper is an outline- 

 of a fuller discussion that must be deferred until the complete 

 statistical results of my own investigations may be brought into 

 relation with those of other investigators of the problem ot natural 

 selection and of its actual basis. 



I. 



In 1899 a brief preliminary investigation was begun upon the 

 pup^ of a saturnid moth, Philosamia cynthia, in order to ascertain 

 whether there was a definite relation between the variability of 

 various pupal structures and the elimination that took place after 

 the larvae spun their cocoons in the fall of the year and pupated. 

 The same question was also examined with reference to the 

 reduction in numbers that occurred when the pup^ne emerged in 



