246 PRESENT-DAY RATIONALISM 



of the most wonderful arrangements in Nature that, in 

 many species, the female lays her eg^c; in places where 

 newly born larvae find just the kind of food they require. 

 The fly lays its eggs on decaying meat, etc., and it is on 

 these substances that the young larv.ne feed." ^ 



I cannot see where the difficulty lies, for the fly was 

 a grub itself once : and has only to remember what it fed 

 on before it fell asleep and woke up as a fly ! 



Another instinct is that of amusement. Probably all 

 animals, if we did but know their habits sufficiently, amuse 

 themselves in some way or another. It is particularly 

 noticeable in domesticated animals, especially the young. 

 It is also very patent in insects, as gnats, flies, butterflies, 

 etc. But what is very apparent is that each kind of 

 animal plays in precisely the same manner generation 

 after generation. We never seem to see any initiative 

 now, though their games must have originated at some 

 time. Thus, flies darting backwards and forwards, 

 pirouetting when they meet, is a familiar instance. Such 

 is a habit which is now evidently hereditary. 



Dogs, cats, and savages as well as mediaeval knights 

 at " play " mimic fighting. This suggests the probable 

 origin of that custom ; while the sexual instinct may 

 account for the "pirouetting" peculiarities of insects. 



Birds again afford many curious habits, each kind 

 amusing themselves after their fashion. Thus the 

 peculiar custom of constructing and decorating " runs " 

 of the bower-birds is characteristic of the genus and 

 an hereditary instinct. 



They know exactly what they like and where to put 

 it. If the bird has placed a brightly coloured object at a 

 particular spot, and it be intentionally shifted by the 



^ Comparative Physiology of the Brain, p, i86. 



