CHAPTER VI 



THE PRACTICAL DETERMINATION OF THE "COEFFICIENT 

 OF DIFFUSION OF CELLS," AND ITS APPLICATION 

 TO THIS IN- VITRO METHOD OF RESEARCH 



IN the foregoing chapter I endeavoured to give an 

 outline of the principles of diffusion of substance into 

 individual cells, and the method of the determination 

 of the coefficient of diffusion. In the present chapter 

 I shall describe, in detail, how those principles are 

 applied experimentally, and how one can find out 

 the coefficient of diffusion of a given class of cells. 

 The preparation of the jellies from which the films 

 are made constitutes the most important part of the 

 procedure. The chemical substances which are to be 

 made to diffuse into the cells are contained in the 

 jelly together with the other chemical factors, which 

 increase or decrease diffusion. The factor heat is 

 measured by keeping the slide on which the jelly-film 

 is set at a certain temperature, and the length of time 

 the slide is kept at this temperature determines the 

 amount of the factor time. The coefficient of diffusion 

 of a cell, as already pointed out, is arrived at by 



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