88 THE NATURK AND ORIGIN OK LIVING MATTER. 



constantly to be found in what we call protoplasm. We have 

 reason to believe that the ultimate products formed arise not 

 suddenly, but by. gradual stages of chemical degradation from 

 the living matter. These transitional products will naturally be 

 present to a variable extent in conjunction with the actually 

 living substance itself. Again, the cell-protoplasm contains 

 nutrient material, and probably (though here we have no clear 

 knowledge) intermediate products between this nutrient material 

 and living matter. How much of this apparent homogeneous 

 protoplasm actually possesses the properties of living matter we 

 do not know, and have no present methods of ascertaining. If, 

 however, we take masses of what is usually termed protoplasm 

 and subject it to chemical examination we can always obtain 

 from it three kinds of matter, fats, carbohydrates, and proteids. 

 Of these the proteids (of which albumin is one) have a mole- 

 cular constitution of peculiar complexity. A chemical formula, 

 which can only be regarded as a rough approximation, C,^ 

 Hn2 SNjH 0.J2 has been assigned to them as the result of 

 analysis. Even if approximately correct, this formula only 

 indicates their minimal complexity. Their real structure might 

 be more correctly indicated by any multiple of this. But the 

 composition of proteids has no relation to that of cell- 

 protoplasm except this, that the latter must be more complex, 

 and may be exceedingly more complex. Furthermore, living 

 protoplasm differs fundamentally from dead proteid in one 

 respect, that it must be regarded as in a peculiar state of 

 unstable chemical equilibrium, while the latter is a comparatively 

 stable substance. To this point I shall return presently. 



Although we are unable to follow the complex physico- 

 chemical changes which we believe to occur in living cells, we 

 are able in one special instance to obtain indirect evidence that 

 such changes do occur. The association of chemical and 

 electrical changes are very obscurely understood in the inorganic 

 world. But it is well known that such an association is real. 

 We have no means of detecting any electric phenomena in the 

 amoeba, but in two highly specialised living tissues, muscle and 

 nerve, of the higher animals we can detect them. If a muscle 

 removed from the body be stimulated by an electric shock (which 

 for present purposes riiay be regarded as instantaneous) the 

 contraction which follows does not occur instantaneously. There 

 is an appreciable interval, calltd the latent period, which 



