100 ox VARIETIES, EACES, SUB-SPECIES, AND SPECIES. 



caused, not by its returning to its wild type or degenerating in 

 the common sense of tlie term, but by its loss of vigour: its 

 fruit becomes scarce, stunted, woody ; its bark, instead of being 

 clean and smooth, is rough, cracked, covered with moss, or de- 

 stroyed by canker ; in short, the plant is a living body the func- 

 tions of which become enfeebled never to be revived ; it advances 

 to a state of decrepitude which is only ended by death. 



M. Puvis, as a reasonable man, could not but extend his 

 opinion to species also, and this lie accordingly has done. He 

 says, " In this way numerous facts justify the opinion, long ago 

 admitted by many people, that the propagation of trees by cut- 

 tings, layers, and suckers, gives a succession of individuals 

 which become weaker and weaker, and steadily degenerate ; the 

 natural consequence is, that the variety is extinguished in suc- 

 cessive generations. . . ." 



He adds, " But is not the same the destiny of species also?" 

 This is what he seeks to prove ; he goes the length of stating, 

 " We might perhaps succeed in showing that it is highly pro- 

 bable that the human species has the same tendency ; that it 

 has already perhaps passed the age of exuberance, strength, and 

 vigour, producing great effects and great things, and the age of 

 great passions, by which nations are moved like single men : we 

 might perhaps be able to show that the intellectual power of the 

 human mind, submitted to all the cliances of the physical or- 

 ganization of the species, is less extensive, less vigorous, less 

 creative ; that we have arrived at the age of maturity when phy- 

 sical strength decreases, ... at the age when organization is 

 enfeebled and capable of less exertion." 



Although M. Puvis admits the influence of soil, exposure, 

 and climate on the quality of plants, he nevertheless attributes 

 to organization, the degeneration and extinction of plants as well 

 as animals. 



Surely if there were not numerous and weighty objections to 

 this view of things (as we iiave seen raised by the facts already 

 collected by us to establish our definitions of species, simple 

 varieties, races, and sub-species, and to show the truth of the 

 principle of immutability of species under existing circumstances), 

 we should be unable to explain how it has happened tliat ob- 

 serving men who have devoted tiieir whole lives to the modifica- 

 tions of plants from all manner of causes, have been of opinion 

 that in the present state of things vegetable species are fixed : 

 that Van Mons denied the possibility of artificially creating races 

 or sub-species from the individuals of a species, and only ad- 

 mitted tliat of creating simple varieties from individuals repre- 

 senting races or sub-species. If M. Puvis's view were correct, 

 why should Sageret have maintained the principle of fixity of 



