382 VITALITY. 



electricity, cliemical affinity, &c., on various forms of matter have been much 

 studied, and a good deal is known about them. Yet among all these results no 

 single instance can be found' resembling the commencement of the functions of 

 vitality. It is, however, admitted that from the outset the vital principle works 

 harmoniously with and by means of the known forces ; so that much of that 

 which was wont to be ascribed to vital force is now known to be a chemical 

 process brought about by the agency of light and heat. But the question is 

 not Avhat light, heat, &c., and vitality can do conjointly, but what light, heat, 

 &c., can do without the presence of vitality; and the reply must, I think, be 

 unfavorable to the correlation which is supposed to exist between vitality and 

 the known forces. 



It may be replied that none of the imponderable forces has ever been alleged 

 to be the force of life ; yet if the latter force is correlative with any of the former, 

 could it behave so differently 1 For example, the known forces act universall} ; 

 there is no kind of matter that is not at all tinoies affected by heat, light, elec- 

 tricity, and chemical affinity ; on the other hand, the force of life stops suddenly 

 and definitely at a limit which excludes a large proportion of existing matter. 



We may now pass again to the alternative. If vitality be not sui generis, it 

 must be something analogous to the agencies with which we are acquainted.. 

 Now of these agents collectively the most certain thing that we can say is, that 

 they are strictly obedient to fixed laws; that under similar circumstances simi ar 

 results invariably follow. So precise and constant is the operation of this rule 

 that, under favorable conditions, we are able to infer the antecedent from the 

 knowledge of the effect, with as much accuracy as we can predict the effect from 

 the knowledge of the antecedent. We are quite certain that no portion of <i 

 result, however minute, can have been produced without a corresponding char- 

 acter having existed in the antecedent. It is not contended that we are able to 

 trace otherwise than very imperfectly the remoter antecedents of the facta 

 observed in inanimate nature, but we are convinced that everywhere the supre- 

 macy of law is absolute. 



If, for example, we could trace the history of a drop of water which trickles 

 down the window pane, we should find that its volume, its direction, its tempe- 

 rature, and all its other characters were derived from atmospheric and other 

 agencies; and if the history of the drop could be submitted to a suitable kind 

 of examination, it would yield up to us the exact qualitative and quantitative 

 characters of all the forces which had collected it and sent it on its course. 

 These forces would indicate their antecedents, till it might be seen that our drop 

 was the inevitable and exact result of meteorological and chemical and mechan- 

 ical changes and actions that had been going on continuously from the Silurian 

 ages, and for we know not how long previously. 



Nor would the whole history of the drop, however remote its starting point, 

 present any very complicated or difficult facts. Some of its particles may have 

 come from the antipodes, or have belonged to the polar snows; others, in a state 

 of decomposition, may have assisted to lift a balloon or have been breathed by 

 an icthyosaurus, yet they were never for an instant beyond the grasp of those 

 known laws which in the end brought them together to be a drop; every step in 

 the whole course being, with the utmost precision, dependent upon the previ- 

 ous one. 



Those who do not admit the vital principle to be a thing sui generis must 

 assign to it a place under the dominion of laws, the rigorous character of the 

 operations of which I have endeavored to illustrate.* If the consequence of 

 such an allocation can be shown to be difficulties unparalleled in magnitude, 

 something will be done towards proving that the allocation is a wrong one, and 

 that the vital principle is a thing not subject to the laws of ordinary forces. 



* Be it remembered, once for all, that on this point there can be no playing fast or loose to 

 suit the occasion. Vitality is, or is not, subject to the exact laws of nature. 



