518 GENERAL PHYSIOLOGY 



From the experiments and observations presented it is evident 

 that between the protoplasm and the nucleus a mutual exchange 

 of substance takes place, without which neither of the two parts 

 of the cell can continue to exist. In other words, both nucleus 

 and protoplasm take part in the metabolism of the whole cell and 

 are indispensable to its continuance. 



B. DERIVATION OF THE ELEMENTARY VITAL PHENOMENA FROM 

 THE METABOLISM OF THE CELL 



1. The Mechanics of Cell-metabolism 

 a. Scheme of Cell-metabolism 



With the inclusion of the nucleus and the protoplasm in the 

 metabolic chain the mechanics of cell-metabolism assumes extra- 

 ordinary complexity. With our lack of knowledge of the special 

 chemical processes in living substance we can at present form no 

 idea of the metabolism of the biogens in the type of cell possessing 

 a differentiated nucleus and protoplasm, nor of the share taken by the 

 two parts of the cell in the various components of this metabolism ; 

 nor do we even know whether we must not assume the existence of a 

 large number of different kinds of biogens in the nucleus and in 

 the protoplasm, whose metabolism is closely interwoven with one 

 another. Although we must leave the solution of all these questions 

 to the future, upon the basis of our present knowledge we can at 

 least form a picture of the great complexity of the metabolic 

 machinery by means of a graphic scheme showing the mutual 

 relations of the surrounding medium, the protoplasm and the 

 nucleus. 



For this purpose it is necessary first to become acquainted 

 with certain new facts. Although the non-appearance of 

 certain phenomena in non-nucleated protoplasmic masses on the 

 one hand, and in nucleated cells with the protoplasm excluded on 

 the other, shows that as regards many metabolic processes the 

 nucleus and the protoplasm are greatly dependent upon each other, 

 with reference to many other phenomena there appears from some 

 experiments a certain independence of the two. For example, 

 certain processes continue in the protoplasm for a considerable 

 time even after the removal of the nucleus. Among these pro- 

 cesses two groups may be distinguished. First, since the nucleus 

 is continually giving off substances to the protoplasm, there always 

 occur in the latter certain quantities of those substances, which 

 we shall term in brief nuclear substances, which cannot be removed 

 with the removal of the nucleus. Hence certain processes, for the 

 occurrence of which the nuclear substances are absolutely 

 necessary, are still able to continue at the expense of those 

 present in the protoplasm since a time previous to the enucleation. 



