VI HABITS OF MOLOTHRUS 265 



to the parents in old age. To be alone in the world is in 

 itself painful. Accordingly the instinct of caring for off- 

 spring is a social instinct, and it belongs, according to my 

 practical view of " reason," to the class of reasoning instincts, 

 since it connects the care for the future of the species with 

 the care for the family. At the lower stages of its evolution 

 the egoistical side of this instinct will still be strongly pro- 

 minent, but as the relations are continually refined, and with 

 the mental evolution of the organism become more manifold 

 and more spiritual, the most ideal conduct results from it. 



Darwin mentions that some species of Molothrus, a genus of 

 American birds, allied to our starlings, have habits like these of 

 the cuckoo. He believes that among the species of this genus a 

 series can be arranged which shows the evolution of the instinct. 

 According to Mr. Hudson, Molothrus badius sometimes 

 builds a nest of her own, sometimes lays her eggs in another 

 bird's after she has thrown out the nestlings of the latter, 

 sometimes builds a nest for herself on the top of the one appro- 

 priated. She usually sits on her own eggs and rears her own 

 young ; but probably she occasionally leaves them to be reared 

 by other birds, for young of this species have been observed 

 clamouring to old birds of another species for food. Another 

 species, Molothrus bonariensis, according to Darwin, has the 

 parasitic instinct much more highly developed. As far as is 

 known, this bird invariably lays its eggs in the nests of others ; 

 but it is remarkable that several together sometimes commence 

 to build an irregular untidy nest of their own in singularly 

 ill -adapted situations, as on the leaves of a large thistle. 

 They never, however, so far as Mr. Hudson ascertained, com- 

 pleted a nest for themselves. They often lay so many eggs 

 — from fifteen to twenty — in the same foster-nest, that few 

 or none can possibly be hatched. They have, moreover, the 

 extraordinary habit of pecking holes in the eggs, whether of 



