178 ESSAYS. 



Here, again, Mr. Knight took an extreme view. In his 

 essay in the "Philosophical Transactions," published in the 

 year 1810, he propounded the theory, not merely of a natural 

 limit to varieties from grafts and cuttings, but even that they 

 would not survive the natural term of the life of the seedling: 

 trees from which they were originally taken. Whatever may 

 have been his view of the natural term of the life of a tree, and 

 of a cutting being merely a part of the individual that pro- 

 duced it, there is no doubt that he laid himself open to the 

 effective replies which were made from all sides at the time, 

 and have lost none of their force since. Weeping- Willows, 

 Bread-fruits, Bananas, Sugar-cane, Tiger-lilies, Jerusalem 

 Artichokes, and the like, have been propagated for a long 

 time in this way, without evident decadence. 



Moreover, the analogy upon which his hypothesis is founded 

 will not hold. Whether or not one adopts the present writ- 

 er's conception, that individuality is not actually reached or 

 maintained in the vegetable 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 individual 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 individuals, by being 

 divided with impunity and advantage, 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 individ- 

 uals, and as they are born they must die, like other individu- 

 als." " 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." 

 Now what people in their senses do dispute is, not that the 

 tree will die, but that other trees, established from cuttings of 

 it, will die with it. 



But does it follow from this that non-sexually propagated 

 varieties are endowed with the same power of unlimited dura- 

 tion that are possessed by varieties and species proj)agated 

 sexually — i. e. by seed ? Those who think so jump too soon 



