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On the first clause, we may say, in the first place, to- 

 wards a proof of difference which will only cumulate, I 

 hope, that, even should we grant in all protoplasm an 

 identity of chemical ingredients, what is called Allotropy 

 may still have introduced no inconsiderable variety. 

 Ozone is not antozone, nor is oxygen either, though in 

 chemical constitution all are alike. In the second 

 place, again, we may say that, with varying proportions, 

 the same component parts produce very various results. 

 By way of illustration, it will suffice to refer to such dif- 

 ferent things as the proteids, gluten, albumen, fibrin, 

 gelatine, etc., compared with the urinary products, urea 

 and uric acid; or with the biliary products, glycocol, 

 glycocolic acid, bili-rubin, bili-verdin, etc. ; and yet all 

 these substances, varying so much the one from the 

 other, are, as protoplasm is, compounds of carbon, hy- 

 drogen, 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 organism are called protoplasm by Mr. 

 Huxley ; but can we predicate chemical identity of 

 muscle and bone, for example ? In such cases Mr. 

 Huxley, it is true, may bring the word " modified " into 

 use ; but the objection of modification we shall examine 

 later. In the mean time, we are justified, by Mr. Hux- 

 ley's very argument, in regarding all organized tissues 

 whatever as protoplasm ; for if these tissues are not to 

 be identified in protoplasm, we must suppose denied 

 what it was his one business to affirm. And it is 

 against that affirmation that we point to the fact of 

 much chemical difference obtaining among the tissues, 

 not only in the proportions of their fundamental ele- 

 ments, but also in the addition (and proportions as well) 



