No. 530] TEMPERATURE ON GROWING MICE 



97 



In the case of a warm-blooded animal, of course, such 

 an explanation as the foregoing could not be offered with- 

 out still further modification. It might be conceded that 

 temperature, as such, could not affect the germ-cells to 

 any appreciable extent. But it might, on the other hand, 

 be contended that the effects of temperature, even upon 

 the parent body itself, may not be direct, but may be due 

 to the formation of specific chemical substances, which, 

 through the medium of the blood, may be supposed to 

 simultaneously influence the body and the germ-cells. 

 Thus we should, after all, be invoking a "simultaneous 

 modification of the germ-plasm," as in the case of cold- 

 blooded animals. 



Such a conception, vague as it is, has certain decided 

 elements of strength. Let me point out, however, as I 

 have already done more than once, that any such chemico- 

 physiological mechanism as is here assumed would be of 

 nearly or quite the same value for evolution as the 

 "inheritance of acquired characters" in the old sense. 

 An interpretation of this sort might "save the face" of 

 certain speculative students of heredity, but the differ- 

 ence between the two views would have little but academic 

 interest. 



At the present time, I am continuing these experiments 

 with mice, and am not only using much larger numbers 

 than hitherto, but am resorting to several variations of 

 the original theme, by which I hope to reduce the number 

 of possible interpretations to a minimum. A friend wrote 

 to me recently, wishing me no end of "good results, not 

 Lamarckian." This doubtless represents the attitude of 

 a large number of persons toward the whole subject. By 

 many, anything with a taint of " Lamarekism" about it 

 would seem to be, ipso facto, beyond the pale of legitimate 

 scientific investigation, belonging rather to the same cate- 

 gory as pre-natal influences, telepathy and the "border- 

 land" phenomena of psychical research. But the dawn 

 of better times is already with us. 



In conclusion, let me state that my own attitude toward 



