Essays on Life 



depend upon the transmission by the germ- 

 cells of certain peculiarities due to the un- 

 favourable climate, which only appear in the 

 full-grown horse." 



But Professor Weismann does not like such 

 cases, and admits that he cannot explain the 

 facts in connection with the climatic varieties 

 of certain butterflies, except "by supposing 

 the passive acquisition of characters produced 

 by the direct influence of climate." 



Nevertheless in his next paragraph but one 

 he calls such cases " doubtful," and proposes 

 that for the moment they should be left aside. 

 He accordingly leaves them, but I have not 

 yet found what other moment he considered 

 auspicious for returning to them. He tells us 

 that " new experiments will be necessary, and 

 that he has himself already begun to undertake 

 them." Perhaps he will give us the results of 

 these experiments in some future book for 

 that they will prove satisfactory to him can 

 hardly, I think, be doubted. He writes : 



"Leaving on one side, for the moment, these 

 doubtful and insufficiently investigated cases, 



we may still maintain that the assumption 



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