246 Tlic World-Evidence. 



And he proceeded to give an illustration in the 

 case of the frugivorous bats (Pteropus poliocephalus) 

 of Australia, which, when grape-growing had been 

 started, came to form so keen a taste for the grapes 

 that, for a time, wine-growing in Australia seemed 

 impossible. But not only will wild animals be at- 

 tracted to the forest by the new grain or fruit — the 

 whole insect life of the district will be changed ; 

 and, following on that change, the bird life and the 

 relation of whole families of birds to other families 

 of birds be conspicuously modified. 



Mr. Hudson's suggestion in that last passage we 

 have quoted would indeed carry us very far — carry 

 us so far that a volume might well be written on it. 

 If other birds profit in certain ways by these vast 

 changes, however gradually carried forward, certain 

 it is, too, that in some ways they lose — for a large 

 body of facts we have had before us connected with 

 the cuckoo and other parasitical birds lead to the 

 conviction that parasitism tends to have its fuller 

 play under the changes introduced by man, and 

 man's advances, in what he calls, and, from his point 

 of view, rightly calls, " improving the country " — 

 which means the improving off the face of the earth 

 necessarily of whole races of innocent creatures, or 

 of the transformation of those that remain into some- 

 thing wholly different from what they were — alike in 

 habit, function, and tendency — it is by such changes 

 and modifications indeed that they survive. Else- 

 where we have entered more fully into this subject. 



In how far may these same operating causes, 

 working to the same or similar results as are sug- 

 gested here, be found in our common cuckoo (i) in 



