6o 



THE MECHANISM OF LIFE 



another in definite patterns. When a liquid diffuses in 

 another undisturbed by the influence of gravity, it produces 

 figures of geometric regularity, and we may thus obtain figures 

 and forms of infinite variety. The following is our method of 

 procedure. A glass plate is placed absolutely horizontal and is 

 covered with a thin layer of water or of saline solution. Then 

 with a pipette we introduce into the solution, in a regular 

 pattern, a number of drops of liquid coloured with Indian ink. 

 A wonderful variety of patterns and figures may be obtained 



by employing solutions 

 of different concentra- 

 tion and varying the 

 position of the drops. 



Instead of the water 

 or salt solution, we 

 may spread on the 

 plate a 5 or 10 per 

 cent, solution of gela- 

 tine, containing various 

 salts in solution. If 

 now we sow on this 

 gelatine drops of vari- 

 ous solutions which 

 give colorations with 

 the salts in the gela- 

 tine, we may obtain 

 forms of perfect regu- 

 larity, presenting most beautiful colours and contrasts. The 

 drops, of course, must be placed in a symmetrical pattern. 

 In this way we may obtain an endless number of ornamental 

 figures. 



In order to cover a lantern slide 8.1 cm. x 10 cm., about 5 c.c. 

 of gelatine is required. To this amount of gelatine we add a 

 single drop of a saturated solution of salicylate of sodium, and 

 spread the liquid gelatine evenly over the plate. When the 

 gelatine has set. we put the plate over a diagram, a hexagon 

 for instance, and place a drop of ferrous sulphate solution at 

 each of the six angles. The drops immediately diffuse 



Fig. 6. — Pattern produced in gelatine by the 

 diffusion of drops of concentrated solutions of 

 nitrate of silver ami bromide of ammonium. 



