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head of that fluid would not keep a hungry man from 

 starving, nor would it save any animal whatever from a 

 like fate. An animal cannot make protoplasm, but must 

 take it ready-made from some other animal, or some plant 

 the animal's highest feat of constructive chemistry be- 

 ing to convert dead protoplasm into that living matter 

 of life which is appropriate to itself. Therefore, in seek- 

 ing for the origin of protoplasm, we must eventually turn 

 to the vegetable world. The fluid containing carbonic 

 acid, water, and ammonia, which offers such a barmecide 

 feast to the animal, is a table richly spread to multitudes 

 of plants ; and with a due supply of only such materials, 

 many a plant will not only maintain itself in vigor, but 

 grow and multiply until it has increased a million-fold, 

 or a million million-fold, the. quantity of protoplasm 

 which it originally possessed ; in this way building up 

 the matter of life, to an indefinite extent, from the com- 

 mon matter of the universe. Thus the animal can only 

 raise the complex substance of dead protoplasm to the 

 higher power, as one may say, of living protoplasm ; 

 while the plant can raise the less complex substances- 

 carbonic acid, water, and ammonia to the same stage 

 of living protoplasm, if not to the same level. But the 

 plant also has its limitations^ Some of the fungi, for ex- 

 ample, appear to need higher compounds to start with, 

 and no known plant can live upon the uncompounded 

 elements of protoplasm. A plant supplied with pure car- 

 bon, hydrogen, oxygen, and nitrogen, phosphorus, sul- 

 phur, and the like, would as infallibly die as the animal 

 in his bath of smelling-salts, though it would be sur- 

 rounded by all the constituents of protoplasm. Nor, 



