NATURAL SELECTION 115 



small plants resort. Or it may be that the fact that"numbers of 

 a kind often grow together makes the wind an efficient pollen- 

 carrier for them. This, at any rate, seems to be the case with 

 the grasses. Able to pack close together in little forests they 

 find the wind serves their turn. In one way many big trees 

 make great efforts, so to put it, to prevent waste. They have 

 developed all manner of contrivances to bring about the scatter- 

 ing of their seeds far and wide so that they may not all be 

 stifled under the parent tree. The wind whirls away the fruit 

 of the sycamore (Acer pseudo-p/atanus), the nut-cracker carries off 

 a fir cone to some favourite perch and from there drops an occa- 

 sional seed, the squirrel now and then drops or forgets his nut. 

 The trees have made elaborate preparations in order to make use 

 even of an occasional chance of portage. 



Marvellous as are the contrivances in the vegetable world to Reduction 

 prevent waste, they are nothing to what we find among animals. 

 In none of the higher classes is Natural Selection allowed to act species 

 in full force upon the young ; during youth its incidence is to a 

 great extent indirect ; that is, if the parents are strong and the 

 circumstances are favourable, they are able to shield their off- 

 spring and surround them with every comfort. Social insects 

 feed and protect their larvae, but it is among the vertebrates 

 that parental care shows itself most conspicuously. The male 

 stickleback l makes a nest and protects the eggs, guarding them 

 even from his own cannibal unmotherly spouse. A queer, 

 isolated phenomenon this. It is only the warm-blooded verte- 

 brates, the birds and mammals, that can be said to fend off 

 Natural Selection from their young. The difficulties are often 

 great. Imagine twelve young tomtits in a nest. The parents 

 are continually dropping grubs into their open mouths. All 

 seem to get their fair share, though how an equal distribution 

 is possible in a dimly-illuminated hole it is difficult to under- 

 stand. Probably there is something of a struggle in the nest, 

 and the weaker come off not quite so well. Among a litter of 

 domestic pigs there is sometimes one that is jostled from the 

 trough, and is lean and under-sized, which one, before the days 



1 Gasterosteus. 



