254 Luck, or Cunning ? 
useless without it obtains a good supply of light and air. 
The architect strives so to produce the house as to attain 
this end, and still leave the house comfortable. But the 
house, though dependent upon, is not produced by, the 
light and air. So a tree is functionally useless, and cannot 
even exist without a proper supply of light and air; but, 
whereas it has been the custom to ascribe the heliotropic and 
other motions to the direct influence of those agents, I would 
rather suggest that the movements are to some extent due 
to the desire of the plant to acquire its necessaries of life.” 
The more I have reflected upon Mr. Tylor’s Carshalton 
experiments, the more convinced I am of their great value. 
No one, indeed, ought to have doubted that plants were 
intelligent, but we all of us do much that we ought not to 
do, and Mr. Tylor supplied a demonstration which may be 
henceforth authoritatively appealed to. 
I will take the present opportunity of insisting upon a 
suggestion which I made in ‘“ Alps and Sanctuaries ”’ 
(New edition, pp. 152, 153), with which Mr. Tylor was 
much pleased, and which, at his request, I made the subject 
of a few words that I ventured to say at the Linnean 
Society’s rooms after his paper had been read. ‘“‘ Admit- 
ting,” I said, ‘‘ the common protoplasmic origin of animals 
and plants, and setting aside the notion that plants pre- 
ceded animals, we are still faced by the problem why 
protoplasm should have developed into the organic life 
of the world, along two main lines, and only two—the ani- 
mal and the vegetable. Why, if there was an early schism 
—and this there clearly was—should there not have been 
many subsequent ones of-equal importance? We see in- 
numerable sub-divisions of animals and plants, but we see 
no other such great subdivision of organic life as that where- 
by it ranges itself, for the most part readily, as either 
animal or vegetable. Why any subdivision ?—but if any, 
why not more than two great classes ? ” 
The two main stems of the tree of life ought, one would 
