VITAL GROWTH AND CRYSTALLIZATION 



33 



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Fig. 18. Skin Formation on the Surface of a Starch Solution (a) 

 and a Cellulose Solution (b) 



On the surface of a starch, gelatin, or cellulose solutions we can see the 

 formation of a delicate skin consisting of one or more nicely arranged 

 "cell" layers, more compact than the underlying loose "cell" arrangement. 

 A similar surface layer or skin is formed on boiled milk and many other 

 liquids. Its structure as revealed by microscopic examination is much 

 more primitive than that of the real skin of plants, animals or man, yet 

 there is a remote resemblance. (Magnified 3600 times.) 



This microphotograph with its extremely delicate structure, as well 

 as those shown in Figs. 13, 14, 16, 17, and 19a, are from O. Bi'itschli, in his 

 days a professor at the University of Heidelberg, a man who worked with 

 painstaking accuracy. The microphotographs of structures in gelatin, 

 starch, etc., which he left to posterity, are performances which required 

 rare skill, and have never been duplicated. Most of them are done with 

 a magnification near the limit of visibility. The striking feature of these 

 pictures is their resemblance to many microscopic aspects of living tissue. 



