236 The World-Evidence. 



mangrove cuckoo {Coccyzns minor) — both brood their 

 own young ; * but surely Professor Newton, in view 

 of the clear evidence that the American cuckoos are 

 found, under certain conditions, laying eggs in other 

 birds' nests, goes too far in absolutely ignoring or 

 quietly setting aside all this evidence. 



The peculiar fact, that in certain latitudes we have 

 varieties of the cuckoo, some of which, at all events 

 up to a certain point, brood their own young and 

 nurse and feed some of their progeny, and yet in 

 structure do not differ substantially from our cuckoos ; 

 and that, outside this, you ha\-e generally a full ten- 

 dency to parasitism, or more or less a clear tendency 

 to it, has not, in our idea, had the attention that it 

 deserves. Either climate or food must have some- 

 thing to do with this, or else points in the structure 

 and economy of these birds have not yet been ob- 

 served, studied, and fully illustrated. Can the fact 

 of comparatively recent settlement by white men, 

 carrying with them the work of civihzation, have 

 anything to do with it ? In latitudes throughout 

 which the work of civilization has for ages gone on, 

 there you will find the cuckoos, or certain of the 

 cuckoos, pronounced parasites, whereas in latitudes 

 more recently opened up to civilization and the intro- 

 duction of the changes that inevitably come in its 

 train, you have cuckoos that are clearly only more or 

 less on the way to full parasitism. 



* Cory, pp. 116 — 117. 



