CHAPTER VII 



SOME ASPECTS OF CELL-CHEMISTRY AND CELL-PHYSIOLOGY 



" Les phenomenes fonctionnels ou de depense vitale anraieut done leur siege dans le 

 protoplasme celhilaire. 



" Le noyau est un appareil de syntlu'se organiqiu, I' instrument de la production, le gertne 

 de la celllller CLAUDE BERNARD.^ 



A. Chemical Relations of Nucleus and Cytoplasm 



It is no part of the purpose of this work to give even a sketch of 

 general cell-chemistry. I shall only attempt to consider certain ques- 

 tions that bear directly upon the functional relations of nucleus and 

 cytoplasm and are of especial interest in relation to the process of 

 nutrition and through it to the problems of development. It has 

 often been pointed out that we know little or nothing of the chemi- 

 cal conditions existing in living protoplasm, since every attempt to 

 examine them by precise methods necessarily kills the protoplasm. 

 We must, therefore, in the main rest content with inferences based 

 upon the chemical behaviour of dead cells. But even here investiga- 

 tion is beset with difficulties, since it is in most cases impossible to 

 isolate the various parts of the cell for accurate chemical analysis, 

 and we are obliged to rely largely on the less precise method of 

 observing with the microscope the visible effects of dyes and other 

 reagents. This difficulty is increased by the fact that both cytoplasm 

 and karyoplasm are not simple chemical compounds, but mixtures of 

 many complex substances ; and both, moreover, undergo periodic 

 changes of a complicated character which differ very wddely in dif- 

 ferent kinds of cells. Our knowledge is, therefore, still fragmentary, 

 and we have as yet scarcely passed the threshold of a subject which 

 belongs largely to the cytology of the future. 



It has been shown in the foregoing chapter that all the parts of 

 the cell arise as local differentiations of an all-pervading substratum 

 which in the greater number of cases, perhaps in all, has the form of 



^ I.e^ons sur les pkenomefies de la 77>, L, 1878, p. 198. 



238 



