THE FUNDAMENTAL PHYSIOLOGICAL ACTIONS. 27 



ities of the cell. So far as the manifestation of the power of 

 movement is concerned the evidence seems in favor of the 

 hyaloplasm : the outermost parts of a white blood-corpuscle, 

 for example, exhibit active contractile power, yet they con* 

 tain no spongioplastic filaments; and many unicellular living 

 things are known in which no reticular structure can be dis- 

 covered and which nevertheless nourish themselves and are 

 reproductive, irritable, contractile, conductive, co ordinative 

 and automatic. It is therefore possible that the filaments 

 when present are to be regarded as secondary in importance 

 to the hyaloplasm, partly serving as a mechanical support; 

 but in addition they may play an important part in the inter- 

 nal economy of the cell. The study of the physiology of in- 

 dividual cells presents very great difficulties and is yet in its 

 beginnings, so that we can do little more than speak of the 

 properties of the cell as a whole, though from the frequent 

 radial arrangement of the cell-protoplasm, in its neighborhood 

 and from the part it plays in the initiation of cell division, 

 the attraction-particle appears to have a very important role. 



Of the actual chemical composition of living matter we 

 know only that its molecule is one of great complexity: all 

 methods of chemical analysis break it up and alter it funda- 

 mentally, so that what is really analyzed is not living matter 

 but a mixture of the products of its decomposition, among 

 which proteid substances are always prominent. 



Cell-protoplasm no doubt varies a little in different cells, 

 so that the name is to be regarded as a general term designat- 

 ing a number of closely-allied substances agreeing with one 

 another chemically in main points, as the proteids do, but 

 differing in minor details, in consequence of which one cell 

 differs from another in faculty. On proximate analysis every 

 mass of protoplasm is found to contain much water and a 

 certain amount of mineral salts; the water being in part con- 

 stituent or entering into the structure of the particles of pro- 

 toplasm, and in part probably deposited in layers between 

 them. Of organic constituents protoplasm always yields one 

 or more proteids, some fats, and some starchy or saccharine / 

 body/ So that the original protoplasm is probably to be re- 

 garded as containing chemical "residues" of proteids, fats 

 and carbohydrates, combined with salts and water. 



The name nuclein has been given to a substance or mix- 

 ture of substances which are left behind when the cell-proto- 



