IX] 



OF LIESEGANG'S RINGS 



663 



interspaced : the result being very closely comparable to the banded 

 pigmentation which we see in the hair of a rabbit or a rat. In the 

 ordinary plate preparation, the free surface of the gelatine is under 

 different conditions to the layers below and especially to the lowest 

 layer of all in contact with the glass; and so we often obtain a 



Fig. 305. Relay- crystals of common salt. After Bowman. 



double series of rings, one deep and the other superficial, whiclj. by 

 occasional blending or interlacing may produce a netted pattern. 

 Sometimes, when only the inner surface of our capillary tube is 

 covered with a layer of gelatine, there is a tendency for the deposit 



Fig. 306. Wheel-like crystals in a colloid. After Bowman. 



to take place in a continuous spiral, rather than in concentric and 

 separate zones. By such means, -according to Kiister*, various 

 forms of annular, spiral and reticulated thickenings in the vascular 

 tissue of plants may be closely imitated ; and he and certain other 

 writers have been incHned to carry the same chemico-physical 



* E. Kiister, Ueber die Schichtung der Starkekorner, Ber. d. botan. Gesellsch. 

 XXXI, pp. 339-346, 1913; Ueber Zonenbildung in kolloidalen Medien, Roll. Ztachr. 

 xiii, pp. 192-194; XIV, pp. 307-319, 1913-14. 



