448 ELECTRICITY IN THE PHENOMENA OF ANIMAL LIFE. 



logically think of the cell as chemically torniiiij;- a part of the medium 

 by which it is surroimdecl, since it draws from thence, and continues to 

 draw from thence, the materials from which it is made up. The cell, 

 althougli distinct from the medium, is but a fraction of it. The chem- 

 ical medium thus extends to the cell which lives in it; the latter in 

 finding its way into the former has but set up a selection among the 

 constituent elements. 



The fundamentally electro-positive materials go to form the substance 

 of the cell itself; the oxygen, or its electro-negative equivalent, remains 

 in the portion of the medium Avhicli is in intimate contact with the 

 matter of the cell, whether on the outside or on the inside of the 

 morphological element which it constitutes. 



Tt follows then, clearly, from this remark that the cell is, properly 

 speaking, but the means of reaction presented to the medium, and, 

 further, that the path for electric conduction that we are looking for 

 must exist between the ceJl and the fractional part of the medium which 

 is in direct relation with it. 



IV.— ON TIIK PART PLAYED BY SELECTIVE ELECTUOLYSIS IN THE PHENOMENON OF 



CELL NUTRITION. 



But before we concern ourselves with this point we ought to look into 

 the phenomenon of cell nutrition and ask ourselves how it is that in 

 the complex medium that surrounds it on all sides the cell is able in 

 someway to choose the elementary particles which suit it; by what 

 directive influence these particles take up their positions and arrange 

 themselves in such a way as to become integral parts of an organized 

 structure; whence finally comes the impulse which determines the 

 special course of the vital circulation of matter and energy, allowing 

 the cell, on the one hand, to assimilate such or such a determinate con- 

 stituent from the medium, while at the same time it gives up, on the 

 other hand, some constituent which has just before formed a part of its 

 structure? 



It is easy to reply to these questions if we go back to the inorganic 

 reaction between zinc and acid, and take it as a new subject of com- 

 parison, imagining now the zinc to be in a finely divided condition. We 

 have seen that in this case the acid, ready to combine with the zinc, is 

 held in check by the electricity set free at the first moment of contact, 

 this electricity counterbalancing or neutralizing its chemical affinity. 



We have the same state of things before us in the growing cell 

 surrounded by a nutrient medium. The albuminoids of the plasma 

 correspond to the finely divided zinc; the oxygen represents the acid 

 of the mineral illustration. 



When this oxygen, kept in the inactive state by favor of the albumi- 

 noids with which it is virtually associated, makes its way with them 

 into the domain of the cell and comes in contact with albuminoid 

 materials of the same kind, but more readily oxidizable for reasons 



