DIFFUSION AND OSMOSIS 



65 



cells imitating all the natural tissues, cells without a mem- 

 branous envelope, cells with thick walls adhering to one 

 another, or cells with wide intracellular spaces. 



The forms of these artificial cells depend on the number 

 and relative position of the drops which represent the nuclei, 

 and on the molecular concentration or osmotic tension of the 

 solution. The number of the cellular polyhedra is determined 

 by the number of centres of diffusion. The magnitude of the 

 dihedral angles, from which radiate three and occasionally four 



Fig. io. — Artificial liquid cells, formed by coloured drops of concentrated 

 salt solution in a less concentrated salt solution. 



walls, depends on the position of the hypertonic poles of 

 diffusion. The curvature of a surface is determined by the 

 differences of concentration on either side. Between isotonic 

 solutions the surface is plane, whilst it is curved between 

 solutions of different osmotic pressures, the convexity being 

 directed towards the hypertonic solution. 



The time required for these artificial cells to grow varies 

 from two to twenty-four hours, according to the concentra- 

 tion of the gelatine, the growth being most rapid in dilute 

 solutions. 



Similar cells may be produced in water. If we pour a 

 thin layer of water on a horizontal plate, and with a pipette 

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