344: DA R WIS I AN A. 



world, it is clear enough that a common plant or tree 

 is not an individual in the sense that a horse or man, 

 or any one of the higher animals, is — that it is an indi- 

 vidual only in the sense that a branching zoophyte 

 or mass of coral is. Solvitur crescendo : the tree and 

 the branch equally demonstrate that they are not indi- 

 viduals, by being divided with impunity and advan- 

 tage, with no loss of life, but much increase. It looks 

 odd enough to see a writer like Mr. Sisley reproducing 

 the old hypothesis in so bare a form as this : " I am 

 prepared to maintain that varieties are individuals, and 

 that as they are born they must die, like other indi- 

 viduals. . . . "We know that oaks, Sequoias, and other 

 trees, live several centuries, but how many we do not 

 exactly know. But that they must die, no one in his 

 senses will dispute." Xow, what people in their senses 

 do dispute is, not that the tree will die, but that other 

 trees, established from its cuttings, will die with it. 



But does it follow from this that non-sexually- 

 propagated varieties are endowed with the same power 

 of unlimited duration that is possessed by varieties 

 and species propagated sexually — i. e., by seed ? Those 

 who think so jump too soon at their conclusion. For, 

 as to the facts, it is not enough to point out the dis- 

 eases or the trouble in the soil or the atmosphere to 

 which certain old fruits are succumbing, nor to prove 

 that a parasitic fungus (Peronospora infestani) is 

 what is the matter with potatoes. For how else would 

 constitutional debility, if such there be, more natural- 

 ly manifest itself than in such increased liability or 

 diminished resistance to such attacks? And if you 

 say that, anyhow, such varieties do not die of old age 



