UnintentioJial Suicide. 179 



jiiHst have originated in the females,'"''- as one pro- 

 nounced American follower and illustrator of Mr. 

 Darwin's doctrines has asserted, have we not in these 

 arguments an additional ground for adhering to our 

 position indicated above that the fit go down and the 

 unfit survive ? 



Nor can aid be got here by any suggestion that 

 increase of males over females is due to thickness of 

 eggshell, since the same will hold of that — the female 

 producing it — and thus the fit, by their very fitness, 

 are made contributory to their own decrease or ex- 

 tinction, or a kind of involuntary, but not the less a 

 real " natural selection," if unintentional, suicide ! ! 



Dr. Brooks in his " Law of Heredity," though in 

 some respects a very decided follower of Darwin, 

 after no end of experiments with animals in inter- 

 breeding, and comparison of his results with those of 

 others, reaches the general conclusion " that there is 

 beyond and behind the action of ' selection,' some 

 more deeply seated law, which determines that the 

 males, shall as a rule be more modified than the 

 females." t Now, it seems to us that our common 

 cuckoo gives something which is not quite consonant 

 with this : and we should be much obliged, should 

 this writing ever reach the eye of Dr. Brooks, if he 

 would give us his views on it. From what is seen 

 above, certainly it is the fact that the female cuckoos 

 undergo more modification in internal organ, and as a 

 result, in functional activity than do the males, if it 

 may be true that the males are more modified in mere 

 outward aspect in view of certain necessities. It is 



* Brooks's Heredity, p. 241. 

 tp. 218. 



