' 



7 6 



THE MECHANISM OE LIFE 





periodic catalysis of peroxide of hydrogen by mercury, 

 thus describes his experiment: "We place in a perfi 

 clean test tube a few cubic centimetres of perfectly 

 mercury. Upon this we pour 10 c.c, of a 10 per cent, sols 

 of hydrogen peroxide. The mercury speedily becomes co\ 

 with a thin, brilliant bronze-coloured pellicle which re 

 light. Then little by little catalysis of the hydrogen per 

 begins, with liberation of oxygen. After some time, fro 

 to twenty minutes, the liberation of gas at the surface 



her the 



ice which 

 ilv similar. 

 „es of matter, 

 there are no 

 'ontinuity. We 

 .teen liquids and 

 'pour, and between 

 [nous, and paste-like 

 ween solids, liquids, and 

 of cohesion, which is 

 ^iiids, and absent in gases. 

 Rrena in which are brought into 

 i cohesion and disintegration. The 

 • orefore a vital one for the biologist, and 

 cinder the conditions which obtain in living 

 Fig. 18 —I liquids of heterogeneous constitution. The 

 ,,i cohesion brought into play under these conditions 

 .nay be beautifully illustrated by a simple experiment. We 

 take a plate of glass, well cleaned and absolutely horizontal. 

 On it we pour a layer of salt water, and in the middle we 

 carefully drop a spot of Indian ink. The drop at once begins 

 to diffuse, and we obtain a circular figure, like the monopolar 

 field of diffusion already described, the rays of diffusion radiating 

 from the centre in all directions. 



If we keep the plate carefully protected from all disturbing 

 influences, after some ten to twenty minutes we shall see the 



coloured particles returning on their path, and the centre of 



;8 



