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 zodphyte 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: ‘“ ] 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 propagated 
sexually — 7. e. by seed? Those who think so jump too soon 
