40 THE NATURE AND ORIGIN OK LIVING MATTER. 



mechanism. Yet it will hardly be denied that nerve fibres are 

 living tissue, and that the conduction of impulses is a vital act. 



Some light seems to be thrown on the unstable chemical 

 equilibrium of living matter by its great susceptibility to the 

 action of a large number of substances, which we call poisons. 

 Many of these are fatal to protoplasm, converting it into dead 

 matter, even when they come into contact with it in infinitesimal 

 dilution. On the physico-chemical theory of living matter this 

 action presents no special difficulty to the understanding. The 

 molecule of strychnine for example can be regarded as a com- 

 plicated piece of mechanism, which when brought into contact 

 with the still more complex mechanism of the cells of the 

 spinal cord at first excites its molecular or other vibrations and 

 disturbances to greater activity, but carrying its action further 

 it deranges this mechanism altogether, in other words the cells 

 are killed. Another poison will diminish the activity of the 

 cells of the spinal cord from the first, and then kill them. On 

 the physico-chemical theory the conflict is not wholly unin- 

 telligible. We can to a certain extent picture to ourselves two 

 mechanisms which interfere with one another. But if we 

 suppose living matter to be inhabited by a metaphysical 

 something, "vitality," how can we imagine the struggle between 

 it and our strychnine molecule ? The vitalists may, to borrow 

 an old witticism, conjure up their " metaphysical grenadier," 

 but how will they make him fight? 



To all this reasoning 1 can imagine the objection raised : 

 " You may, perhaps, in a few instances, and to a small extent, 

 discover physico-chemical analogies in the behaviour of living 

 matter. All this is beside the point. No mechanism, however 

 complicated, no possible combination of atoms and molecules 

 can be conceived to explain all the activities of protoplasm." 

 Here, I think, we come upon the " stupid, senseless matter " of 

 our old author. If we arbitrarily conceive of our atoms and 

 molecules as so many hard, round particles, like small shot, only 

 much smaller, such an objection is natural. But this conception 

 is a purely arbitrary one. We cannot at present form any clear 

 idea of the structure of non-living matter which will explain all 

 the phenomena which it presents. For instance, who of us has 

 any clear conception of what takes place in and around a metallic 

 wire when a current of electricity is passed through it "? Or, to 

 ask another question, how can we explain the attraction that 



