OF ORGANIC NATURE. 21 



started. So that you see, this living animal, this horse, 

 begins its existence as a minute particle of introgenous 

 matter, which, being supplied with nutriment (derived, 

 as I have shown, from the inorganic world), grows up 

 according to the special type and construction of its 

 parents, works and undergoes a constant waste, and 

 that waste is made good by nutriment derived from 

 the inorganic world ; the waste given off' in this way 

 being directly added to the inorganic world ; and 

 eventually the animal itself dies, and, by the pn 

 of decomposition, its whole body is returned to those 

 conditions of inorganic matter in which its substance 

 originated. 



This, then, is that which is true of every living 

 form, from the lowest plant to the highest animal — to 

 man himself. You might define the life of every one 

 in exactly the same terms as those which I have now 

 used; the difference between the highest and the 

 lowest being simply in the complexity of the develop- 

 mental changes, the variety of the structural forms, 

 the diversity of the physiological functions which are 

 exerted by each. 



If I were to take an oak tree as a specimen of the 

 plant world, I should find that it originated in an acorn, 

 which, too, commenced in a cell ; the acorn is placed 

 in the ground, and it very speedily begins to absorb 

 the inorganic matters I have named, adds enormously 

 to its bulk, and w T e can see it, year after year, extend- 

 ing itself upward and downward, attracting and ap- 

 propriating to itself inorganic materials, which it vivi- 

 fies, and eventually, as it ripens, gives off its own 

 proper acorns, which again run the same course. But 

 I need not multiply examples — from the highest to the 



