72 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



upon any one of those things which determine the survival of the most 

 fortunate. " Natural Selection " is a " natural law " ; that is, it is only an 

 observed fact, always occurring under similar circumstances ; but like " law '* 

 it can do nothing of itself, both being merely metaphorical expressions for 

 "observed orders of facts." Darwin's first mistake was therefore the insertion 

 of "structure" among the causes of limitation which Malthus enumerates. 



Malthus showed that the population (i.e. of man) increased in a 

 geometrical, but his food materials in arithmetical progression. 



As far as the human race is concerned, it may be true, for man can 

 establish himself in all parts of the world, since his intelligence enables 

 him to overcome natural enemies ; but his food supply, such as corn, can 

 be made by artificial means to increase at a far higher geometrical 

 rate than himself, as to thirtyfold or a hundredfold. Moreover, he can 

 bring enormous areas, now naturally barren, under cultivation, as we are 

 doing in Egypt, and shall do in South Africa, by means of irrigation, so 

 that Malthus' theory in the eighteenth century requires some modification 

 in the twentieth. But recognising this to some degree, Malthus seems to 

 show that for any given area, say England, the amount of land capable of 

 cultivation must sooner or later come to an end, but the population will 

 still go on increasing. It seems by calculating in this way he would 

 make the rates of increase so divergent, though both crops and cattle 

 per se increase by geometrical progression. 



The causes of limitation to which Malthus refers are locally famines, 

 generally a feeble constitution and poverty in circumstances, where 

 infant mortality is much greater than elsewhere, zymotic diseases, &c. 

 With nature in the wild state things are somewhat different. With both 

 animals and plants the offspring annually born is far in excess of the 

 proportion that can live to maturity. A general result, however, is that 

 an average remains constant, so that there must be a vast amount of 

 destruction in the young state. The struggle for existence is often intense, 

 and the question is, What is the cause of that destruction ? 



Many, of course, form the prey of others ; indeed, the whole of the 

 animal world lives directly or indirectly on plants. Many plants are 

 crowded out by the stronger individuals, whether of the same kind or of 

 other sorts when growing thickly together. Many seeds perish through ill 

 luck, or, as Darwin calls it, " fortuitous destruction," * by falling on barren 

 soil, on which they may germinate, but quickly perish. 



Many seeds are much smaller than others from the same capsule in 

 consequence of their not having been able to store up so much endosperm 

 or reserve food materials for the embryo. The larger seeds on germination 

 get a better start, and soon smother the others if growing in a mass 

 together. 



Anything, therefore, which can give an advantage to one individual 

 above another has a better chance of surviving, so that of a hundred 

 seedlings perhaps not half a dozen grow to maturity. The others perish 

 in infancy. This is what Darwin calls " natural selection," a term 

 which merely indicates what goes on in nature, just as a " natural law " only 

 means what we see always taking place under the same circumstances. 



I shall now quote the passage where Darwin defines natural selection. 

 * Origin of Species, p. G8. 



