370 INDUCTION. 



The first sign is, if between the antecedent a and the consequent b there 

 be evidence of some intermediate link ; some phenomenon of which we can 

 surmise the existence, though from the imperfection of our senses or of our 

 instruments we are unable to ascertain its precise nature and laws. If there 

 be such a phenomenon (which may be denoted by the letter x), it follows 

 that even if a be the cause of h, it is but the remote cause, and that the 

 law, a causes 5, is resolvable into at least two laws, a causes a;, and x causes 

 b. This is a very frequent case, since the operations of nature mostly take 

 place on so minute a scale, that many of the successive steps are either im- 

 perceptible, or very indistinctly perceived. 



Take, for example, the laws of the chemical composition of substances ; 

 as that hydrogen and oxygen being combined, water is produced. AH we 

 see of the process is, that the two gases being mixed in certain proportions, 

 and heat or electricity being applied, an explosion takes place, the gases 

 disappear, and water remains. There is no doubt about the law, or about 

 its being a law of causation. But between the antecedent (the gases in a 

 state of mechanical mixture, heated or electrified), and the consequent (the 

 production of water), there must be an intermediate process which we do 

 not seCo For if we take any portion whatever of the water, and subject it 

 to analysis, we find that it always contains hydrogen and oxygen ; nay, the 

 very same proportions of them, namely, two-thirds, in volume, of hydrogen, 

 and one-third oxygen. This is true of a single drop ; it is true of the mi- 

 nutest portion which our instruments are capable of appreciating. Since, 

 then, the smallest perceptible portion of the water contains both those sub- 

 stances, portions of hydrogen and oxygen smaller than the smallest percep- 

 tible must have come together in every such minute portion of space ; must 

 have come closer together than when the gases were in a state of mechan- 

 ical mixture, since (to mention no other reasons) the water occupies far less 

 space than the gases. Now, as we can not see this contact or close ap- 

 proach of the minute particles, we can not observe with what circumstances 

 it is attended, or according to what laws it produces its effects. The pro- 

 duction of water, that is, of the sensible phenomena which characterize the 

 compound, may be a very remote effect of those laws. There may be in- 

 numerable intervening links; and we are sure that there must be some. 

 Having full proof that corpuscular action of some kind takes place pre- 

 vious to any of the great transformations in the sensible properties of sub- 

 stances, we can have no doubt that the laws of chemical action, as at pres- 

 ent known, are not ultimate, but derivative laws ; however ignorant we may 

 be, and even though we should forever remain ignorant, of the nature of 

 the laws of corpuscular action from which they are derived. 



In like manner, all the processes of vegetative life, whether in the vege- 

 table properly so called or in the animal body, are corpuscular processes. 

 Nutrition is the addition of particles to one another, sometimes merely 

 replacing other particles separated and excreted, sometimes occasioning 

 an increase of bulk or weight so gradual that only after a long contin- 

 uance does it become perceptible. Various organs, by means of peculiar 

 vessels, secrete from the blood fluids, the component particles of which 

 must have been in the blood, but which differ from it most widely both in 

 mechanical properties and in chemical composition. Here, then, are abun- 

 dance of unknown links to be filled up ; and there can be no doubt that the 

 laws of the phenomena of vegetative or organic life are derivative laws, de- 

 pendent on properties of the corpuscles, and of those elementary tissues 

 which are comparatively simple combinations of corpuscles. 



