28 AS REGARDS PROTOPLASM, ETC. 



lias been allowed to constitute us all. But materialism has not 

 on that account been the irresistible result. Attention hitherto 

 and surely excusably, or even laudably in such a case has 

 been given not so much to the dust as to the " potter," and the 

 " artifice " by which he could so transform, or, as Mr Huxley 

 will have it, modify it. To ask us to say clay, or even proto- 

 plasm, instead of dust, is not to ask us for "much, then, seeing that 

 even to Mr Huxley there still remain both the " potter " and his 

 " artifice." 



But to return : To Mr Huxley, when he says all bricks, being 

 made of clay, are the same thing, we answer, Yes, undoubtedly, 

 if they are made of the same clay. That is, the bricks are 

 identical if the clay is identical ; but, on the other hand, by as 

 much as the clay differs will the bricks differ. And, similarly, 

 all organisms can be identified only if their composing proto- 

 plasm can be identified. To this stake is the argument of Mr 

 Huxley tied. 



This argument itself takes, as we have seen, a threefold 

 course : Mr Huxley will prove his position in this place by 

 reference, firstly, to unity of faculty; secondly, to unity of 

 form ; and thirdly, to unity of substance. It is this course of 

 proof, then, which we have now to follow, but taking the 

 question of substance, as simplest, first, and the others later. 



By substance, Mr Huxley understands the internal or chemi- 

 cal composition ; and, with a mere reference to the action of 

 reagents, he asserts the protoplasm of all living beings to be an 

 identical combination of carbon, hydrogen, oxygen, and nitro- 

 gen. It is for us to ask, then, Are all samples of protoplasm 

 identical first, in their chemical composition, and, second, under 

 the action of the various reagents ? 



On the first clause, we may say, in the first place, towards a 

 proof of difference which will only cumulate, I hope, that, even 

 should we grant in all protoplasm an identity of chemical in- 

 gredients, what is called Allotropy may still have introduced 

 no inconsiderable variety. Ozone is not antozone, nor is oxy- 

 gen either, though in chemical constitution all are alike. In 

 the second place, again, we may say that, with varying pro- 

 portions, the same component parts produce very various results. 

 By way of illustration, it will suffice to refer to such different 

 things as the proteids, gluten, albumen, fibrin, gelatine, &c., 

 compared with the urinary products, urea and uric acid ; or with 

 the biliary products, glycocol, glycocholic acid, bili-rubin, bili- 

 verdin, &c. ; and yet all these substances, varying so much the 

 one from the other, are, as protoplasm is, compounds of carbon, 

 hydrogen, oxygen, and nitrogen. But, in the third place, we 

 are not limited to a may say ; we can assert the fact that all 

 protoplasm is not chemically identical. All the tissues of the 



