330 SPECIAL INSTINCTS. [Chap. Vlll. 



Special Instincts. 



We shall, perhaps, best understand how instincts in 

 a state of nature have become modified by selection by 

 considering a few cases. I will select only three, — 

 namely, the instinct which leads the cuckoo to lay her 

 eggs in other birds' nests; the slave-making instinct of 

 certain ants; and the cell-making power of the hive- 

 bee. These two latter instincts have generally and 

 justly been ranked by naturalists as the most wonderful 

 of all known instincts. 



Instincts of the Cuckoo. — It is supposed by some 

 naturalists that the more immediate cause of the in- 

 stinct of the cuckoo is, that she lays her eggs, not daily, 

 but at intervals of two or three days; so that, if she were 

 to make her own nest and sit on her own eggs, those 

 first laid would have to be left for some time unincu- 

 bated, or there would be eggs and young birds of dif- 

 ferent ages in the same nest. If this were the case, the 

 process of laying and hatchiiig might be inconveniently 

 long, more especially as she migrates at a very early 

 period; and the first hatched young would probably have 

 to be fed by the male alone. But the American cuckoo 

 is in this predicament; for she makes her own nest, and 

 has eggs and young successively hatched, all at the same 

 time. It has been both asserted and denied that the 

 American cuckoo occasionally lays her eggs in other 

 birds' nests; but I have lately heard from Dr. Merrell, 

 of Iowa, that he once found in Illinois a young cuckoo to- 

 gether with a young jay in the nest of a Blue jay (Gar- 

 rulus cristatus); and as both were nearly full feathered, 

 there could be no mistake in their identification. I 

 could also give several instances of various birds which 



