CHEMISTRY AND PROTOPLASM 189 



and descending substances ; it also contains others in 

 solution and invisible for, like a lump of jelly (such as 

 the cook serves up shaped by a mould and soaked with 

 flavour and colour), protoplasm can soak up either a large 

 or a small quantity of water, and with the water (that is 

 the important point) all sorts of chemical bodies soluble 

 in water. Just as a lump of quivering calves'-foot jelly 

 (which is a chemical compound of a lower grade than 

 proteids, but like them), when placed in a shallow dish 

 of water coloured red by carmine, does not dissolve in 

 the water, but absorbs the water and the carmine, allowing 

 the coloured water and any chemical bodies in solution 

 in it to diffuse into and become physically, though not 

 chemically, a part of its substance, so protoplasm takes 

 up water and the compounds dissolved by it. Just as a 

 " jelly " of water-holding gelatine can give up its water 

 and become hard and horny, so is protoplasm capable of 

 gradually giving up much of its water, and even in some 

 cases of becoming hard and horny, yet able to return, 

 when remoistened, to its active state. Moreover, a 

 "jelly" can be made to "soak up" or take into itself 

 water and let it pass through its substance, so as to wash 

 out from it all soluble matters. In the same way the 

 protoplasm of a living cell is supplied with nourishing 

 and oxygenating fluids which diffuse into it, and is 

 " washed out," purified, and cleansed of waste or effete 

 chemical compounds by the water which first permeates 

 it, and then diffuses out of it into surrounding watery 

 fluids carrying the excess of soluble chemical bodies 

 with it. 



Whilst proteids are the compounds of the highest 

 stage of chemical complexity recognised in protoplasm, 

 and appear to form the bulk of its substance, we must 

 carefully avoid the error (which is not uncommon) of 

 supposing that protoplasm is itself a definite chemical 



