294 EVOLUTION AND DISSOLUTION. 



amount of molecular motion it receives from the Sun and 

 Earth, exceeds that which it loses by radiation into space 

 and towards adjacent surfaces; while, contrariwise, if, drift- 

 ing over cold mountain tops, it radiates to them much more 

 heat than it receives, the loss of molecular motion is fol- 

 lowed by increasing integration of the vapour, ending in 

 the aggregation of it into liquid and the fall of rain. Here, 

 as elsewhere, the integration or the disintegration is a differ- 

 ential result. 



In living aggregates, and more especially those classed 

 as animals, these conflicting processes go on with great activ- 

 ity under several forms. There is not merely what we may 

 call the passive integration of matter, that results in inani- 

 mate objects from simple molecular attractions; but there is 

 an active integration of it under the form of food. In addi- 

 tion to that passive superficial disintegration which inani- 

 mate objects suffer from external agents, animals produce in 

 themselves active internal disintegration, by absorbing such 

 agents into their substance. While, like inorganic aggre- 

 gates, they passively give off and receive motion, they are 

 also active absorbers of motion latent in food, and active ex- 

 penders of that motion. But notwithstanding this compli- 

 cation of the two processes, and the immense exaltation of 

 the conflict between them, it remains true that there is 

 always a differential progress towards either integration or 

 disintegration. During the earlier part of the cycle of 

 changes, the integration predominates there goes on what 

 we call growth. The middle part of the cycle is usually 

 characterized, not by equilibrium between the integrating 

 and disintegrating processes, but by alternate excesses of 

 them. And the cycle closes with a period in which the dis- 

 integration, beginning to predominate, eventually puts a 

 stop to integration, and undoes what integration had origi- 

 nally done. At no moment are assimilation and waste so 

 balanced that no increase or decrease of mass is going on. 

 Even in cases where one part is growing while other parts 



