Source of Motions upon the Earth. 151 



without some such arrangement as this, under which the individual 



living existences died, and by restoring their matter to its inorganic 

 form, so yield a supply of organizable substances. 



We have here again another instance of two different motions 

 being maintained in activity by their alternate operation, and have 

 set before us another of those circles in which motion continually 

 proceeds. In the former instances, or in those which we termed 

 the physical motions, this alternation was brought about by the rota- 

 tion of the earth. Here we have the continuance of vital and che- 

 mical actions, occasioned most notably by the temporary existence of 

 individual vegetable beings ; but we have it also maintained in a less 

 degree, throughout the whole life of the plant, by the rotation of day 

 and niglit, and of the seasons of the year. Thus, in the presence of 

 sunlight, the forces of life become either more intense, or what per- 

 haps is more probable, and what comes virtually to the same thing, 

 the power of the foi'ces opposing these is lowered, and the molecules 

 of bodies are, to some extent, sundered from each other. Of bodies 

 in this state, the opei'ation of the vital forces probably completes the 

 decomposition ; what is wanted by the plant is assimilated and vital- 

 ised by it, and what is useless to it is left behind. In this manner, 

 plants, under the influence of sunlight, decompose carbonic acid, 

 assimilate the carbon and evolve the oxygen. But on the cessation 

 of sunlight, and during the presence of night, an opposite action takes 

 place ; the vital forces are depressed or rendered less active, the 

 chemical forces gain the ascendancy, and of the carbon which the 

 plant had appropriated, part is recovered by the oxygen of the air, 

 and is evolved from it as carbonic acid. Again, we have the action 

 of the chemical forces brought into play during the life of a plant at 

 somewhat longer intervals by the rotation of the seasons. During 

 the warm months of the year, vitality is the predominant force of a 

 plant, and its growth progresses with rapidity and energy. But in 

 the cold months, its vital forces become dormant, its leaves and other 

 weak parts die, and are decomposed by the chemical forces. 



Let it now be conceived that the higher sorts of animals appear 

 upon the globe, — first herbivorous animals, and afterwards the carni- 

 vorous. Under the dbect influence of solar light and heat, and in 

 the condition of the globe to which these, as well as the other mo- 

 tions induced by external nature, have given rise ; by means of the 

 pure water which the sun has distilled, and by the vegetable bodies 

 which life, under the direction and influence of the same power, has 

 brought into being, the animals will be perfected and preserved in 

 existence. With the appearance of animal life, a number of mo- 

 tions, and some of them of a new, and, as compared with others, 

 an anomalous sort, arise. Animal beings, like plants, have only a 

 temporary existence, and for the like reasons. After a certain pe- 

 I'iod they die, and the substances of which they ai'o composed are re- 

 torcd to the influence of their chemical afllnities, and return to an 



