BIOLOGY. 275 



eafh other. It would be poor pliilosophy to invoke an external 

 agent in the one case, and to reject it in the other. 



*' Instead of cutting our grain of corn into thin slices, and sub- 

 jecting it to the action of polarized light, let us place it in the 

 earth, and subject it to a certain degree of warmth. In other 

 words, let the molecules, both of the corn and of the surrounding 

 earth, be kept in a state of agitation ; for warmth is, in the eye 

 of science, tremulous molecular motion. Under these circura- 

 Ftnnces, the grain and the substances which surround it interact, 

 and a molecular architecture is the result of tiiis interaction. A 

 bud is formed ; this bud reaches the surface, where it is exposed 

 to the sun's rays, which are also to be regarded as a kind of vibra- 

 tory motion. And as the common motion of heat, with which the 

 grain and the substances surrounding it were first endowed, ena- 

 bled the grain and these substances to coalesce, so the specific 

 motion of the sun's ra^-s now enables the green bud to feed upon 

 the carbonic acid and the aqueous vapor of the air, appropriating 

 those constituents of both for which the blade has an elective at- 

 traction, and permitting the other constituent to resume its place 

 in the air. Thus forces are active at the root, forces are active in 

 the blade, the matter of the earth and the matter of the atmos- 

 phere are drawn toward the plant, and the plant augments in size. 

 We have in succession the bud, the stalk, the ear, the full corn in 

 the ear ; for the forces here at play act in a cycle, which is com- 

 pleted by the production of grains similar to that with which the 

 process began. 



" Now there is nothing in this process which necessarily eludes 

 the power of mind as we know it. An intellect the same in kind 

 as our own would, if only sufficiently expanded, be able to follow 

 the whole process from beginning to end. The duly expanded 

 mind would see in the process and its consummation an instance 

 of the play of molecular force. It would see every molecule 

 placed in its position by the specific attractions and repulsions ex- 

 erted between it and other molecules. Nay, given the grain and 

 its environment, an intellect sufficiently expanded might trace out 

 a priori every step of the process, and by the application of me- 

 chanical jDrinciples would be able to demonstrate that the cycle of 

 actions must end, as it is seen to end, in the reproduction of forms 

 like that with which the operation began. A necessity rules here 

 similar to that which rules the planets in their circuits round the 

 sun. 



" But I must go still further, and affirm that in the eye of sci- 

 ence the animal body is just as much the product of molecular 

 force as the stalk and ear of corn, or as the crystal of salt or sugar. 

 Man\' of its parts are obviously mechanical. Take the human 

 heart, for example, with its exquisite system of valves, or take the 

 eye or the hand. Animal heat, moreover, is the same in kind as 

 the heat of a fire, being produced by the same chemical process. 

 Animal motion, too, is as directly derived from the food of the 

 animal as the motion of Trevetliyck's walking-engine from the 

 fuel in its furnace. As regards matter, the antmal body creates 

 nothing; as regards force, it creates nothing. 



