ch. in.] EVOLUTION AND DISSOLUTION. 321 



that dead organisms, from which all supply of molecular 

 motion from without is artificially cut off, are not decom- 

 posed. It is thus that animal remains are preserved for 

 ages in blown sand and in peat-moss. And it is thus that 

 the carcases of primeval mammoths, intact even to the bulbs 

 of the eyes, are found imbedded in arctic ice near the mouths 

 of Siberian rivers, just where they were slain by the cold a 

 thousand centuries ago. 1 



But the study of organic phenomena shows us that our 

 general theorem needs some further revision. As it now 

 stands, it runs some risk of being supposed to assert that the 

 career of any composite body is at first characterized solely 

 by the concentration of matter and concomitant dissipation 

 of motion, and is at last characterized solely by the diffusion 

 of matter and concomitant absorption of motion. A reference 

 to the history of any organism will at once show that this is 

 not the case. While the human body, for example, is con- 

 tinually incorporating with its tissues new matter in the 

 shape of prepared food, large portions of the matter once in- 

 corporated are continually diffused in the shape of excretions 

 through the lungs, liver, skin, and kidneys. And while it is 

 constantly parting with motion, in the shape of radiated 

 heat, of expended nerve-force, and of molar motion com- 

 municated to the surrounding objects which it touches or 

 handles, it is at the same time absorbing large quantities of 

 molecular motion latent in its prepared nutriment. But at 

 jio time are the antagonist processes exactly balanced. During 

 early life the excess of concentration over diffusion of matter 

 results in growth. At a later date the > rhythms due to the 

 alternate predominance of concentration and diffusion, are ex- 

 hibited in continual fluctuations in weight. Yet the fact that 

 the healthy body usually increases in weight up to a late 

 period, shows that ordinarily concentration is still predo- 



1 The heads of these animals are nearly always directed southward. See 

 Lyell, Principles of Gcolojy, 10th edit. vol. i. p. 184. 



VOL. L Y 



