108 THE CELL DOCTRINE. 



other saline matters, contains all the elementary 

 bodies which enter into protoplasm, yet an animal 

 cannot make protoplasm out of these. And this is 

 characteristic. It must take it ready made from 

 some other animal or some plant, the animal's highest 

 feat of constructive chemistry being to convert dead 

 protoplasm into the living matter of life, which is 

 appropriate to itself. Therefore, in seeking for the 

 origin of protoplasm, we must eventually turn to the 

 vegetable world. The plant, however, takes carbonic 

 acid, water, and ammonia,' and converts it to the 

 same stage of living protoplasm with itself, though 

 some of the fungi need higher compounds to start 

 with ; and no plant can live on the uncompounded 

 elements of protoplasm, and the absence of anj' one 

 of the elements renders the plant unable to manufac- 

 ture protoplasm. These elements, carbon, hydrogen, 

 oxygen, and nitrogen, are related to the protoplasm 

 of the plant as the protoplasm of the plant to the 

 animal. 



Thus far it is plain that the views of Prof. Huxley 

 accord with those of many eminent histologists and 

 physiologists, the result of whose observations have 

 been embodied in these pages, and his descriptions 

 will be accepted as undoubtedly accurate. More 

 widely, in common with the school of so-called 

 " physicists," of which he is one, does he differ in 

 his views as to the phenomena exhibited by protoplasm. 



According to Huxley, protoplasm once produced, all 

 the phenomena exhibited by it are simply its properties, 

 just as the phenomena exhibited by water in its various 

 states are properties. They do not take place through 



