34O PRE-DETERMINATION IN NATURE 



four or six ? In the case of man we see that individuals who 

 have lost one finger have the use of the hand impaired, while 

 the few who happen to have six do not seem to be the better. 

 How it was with the old Batrachians we do not know; but it is 

 certain that if we could have amputated the claw-bearing little 

 toe of Sauropus unguifer^ or the reflexed little toe of Cheirothe- 

 rium, we should have much injured their locomotive power. 



The vegetable kingdom is full of similar examples of the early 

 settlement of great questions. Perhaps nothing is more mar- 

 vellous than the power of the green cells of the leaf as workers 

 of those complex and inimitable chemical changes whereby out 

 of the water, carbon dioxide and ammonia of the soil and the 

 atmosphere, the living vegetable cell, with the aid of solar 

 energy, elaborates all the varied organic compounds produced 

 by the vegetable kingdom. Yet this seems all to have been 

 settled and perfected in the old Silurian period, long before any 

 kind of plant now living was on the earth. Perhaps in some 

 form it existed even in the Laurentian age, and was instru- 

 mental in laying up its great beds of carbon. So all that is 

 essential in plant reproduction, whether in that simpler form in 

 which a one-celled spore is the reproductive organ, or in that 

 more complex form in which an embryo plant is formed in the 

 seed, with a store of nourishment laid up for its susten- 

 ance. 



These arrangements were obviously as perfect in the great 

 club mosses and pines of the Devonian and Carboniferous as 

 they have ever been since, and we have specimens so preserved 

 as to show their minute parts just as well as in recent plants. 

 The microscope also shows us that the contrivances for thicken- 

 ing and strengthening the woody fibres and trunk of the stem 

 by bars or interrupted linings of ligneous matter, so as to give 

 strength and at the same time permit transudation of sap, were 

 all perfected, down to their minutest details, in the oldest land 

 plants. It is true that flowers with gay petals and some of the 



