The Evolution of the Sciences 



vessel, or instead, to drop some potassium 

 ferrocyanide on a thin layer of gelatine; the 

 dye will show the cellular disposition, produced 

 automatically by diffusion. According to the 

 conditions of the experiment, we obtain poly- 

 hedral cells, or fibre-shaped cells, or cells with 

 ciliary prolongations or with dendritic ramifica- 

 tions as in nerve-cells. All these cells have 

 their nucleus; they are the seat of internal 

 movements, and osmotic exchanges take place 

 from one to the other. As early as 1866, 

 Traube, a chemist and wine merchant of Breslau, 

 had produced real artificial cells by letting fall 

 a drop of dissolved copper sulphate into a 

 solution of potassium ferrocyanide; the reaction 

 of the two bodies formed, on the surface of the 

 drop, a gelatinous envelope of copper ferrocy- 

 anide, but the utricle formed in this manner was 

 incapable of growth. M. Leduc has reached 

 much more suggestive results by adding to the 

 liquids used by Traube other suitably selected 

 substances. The drop, or the initial cell, under- 

 goes a considerable development in a time 

 varying from a few minutes to several days, 



and resulting in the production of a real cellu- 



274 



