CHAPTER VII 



SOME ASPECTS OF CELL-CIIEMISTRY AND CELL-PHYSIOLOGY 



" Les ph^nomSnes fonctionnels ou de dSpense vitale auraieut done leur siege dans Ic proto- 

 plasnie cellulaire. 



" Le noyau est un appareil de syiithese orgauique, l' instrument de la production , le germe de la 

 cellule." Claude Bernard.i 



I 



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 chemical 

 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 investigation is be- 

 set 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 com- 

 plicated character which differ very widely in different 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 a general protoplasmic basis. 

 Despite the difficulties of chemical analysis referred to above, it has 

 been determined wath certainty that some at least of these organs are 

 the seat of specific chemical change ; just as is the case in the various 

 organs and tissues of the organism at large. Thus, the nucleus is 



^ Le(;ons siir les phenonunes de la vie, I., 1878, p. 198. 



330 



