Life and Death, Heredity and Evolution 



but a few words of comment will aid in obtaining an outline 

 of the present situation in science. 



Standfuss and Fischer, by the application of low tem- 

 peratures to the pupae of certain butterflies, induced in a 

 small proportion of the adults the appearance of darker 

 tinges of color than usual. In a small proportion of these 

 aberrant adults, the modified color reappeared in later gen- 

 erations; it was hereditary. 



Tower tried the effects of hot, moist conditions on the 

 potato beetle at the time that the germ cells were under- 

 going their growth and transformation. He found that 

 the germ cells so treated produced a considerable proportion 

 of individuals differing from the typical ones; lighter in- 

 dividuals and darker ones. And in later generations these 

 aberrant colors showed themselves to be hereditary. 



Kammerer experimented for many years in breeding vari- 

 ous sorts of amphibians, attempting through climatic 

 changes, alterations of temperature and moisture, changes in 

 color of the background on which they live, and by other 

 means, including operations, to modify their colors, habits 

 and other characters. According. to his detailed reports, 

 published in the technical scientific journals, he has been re- 

 markably successful in this ; many sorts of diversities in en- 

 vironmental conditions have produced inherited alterations ; 

 including even operative procedures. These positive results 

 have come to him so easily and regularly, in experiments of a 

 sort in which others have practically universally reached neg- 

 ative results, as to arouse in most investigators a feeling that 

 they must be confirmed by others before they can be accepted. 

 It must be said however that Kammerer's work appears to 

 have been done with great thoroughness and care, and he 

 has given full account of his methods and results, in such a 

 way as to leave little room for criticism of details. On the 



