﻿S4 FIELD AND FOREST. 



The general reader should understand that there are only three sub- 

 stances known in nature, cholesterine, cellulose, and starch, which ex- 

 hibit a blue color when sulphuric acid tincture, or solution of iodine- 

 are applied to them. Cholesterine is found in many animal and veg- 

 etable substances. Cellulose composes the cell-walls of plants. The 

 pith of plants and the pure fibers of cotton and flax consist of it. 

 Starch and cellulose are identical in composition and by well-known 

 chemical methods cellulose may be converted into starch the latter 

 into dextrine, and dextrine into grape-sugar; but by the use of sul- 

 phuric acid, cellulose or starch may be converted into grape-sugar di- 

 rectly without passing into dextrine, as an intermediate stage. Put a 

 few grains of pure starch in a vessel containing distilled water, and 

 place by the side of it a second vessel containing a weak solution of 

 the chloride of ammonium ; place both vessels under cover, and expose 

 them to a temperature of about 70 , say for a period of about six 

 months, when if examined it will be found that no chemical change of 

 these substances has taken place; but, on the other hand, if these liquids 

 are united in one vessel, and kept under a temperature of about 70 , 

 vegetable growth will commence within a few days, provided there is 

 an air space above the liquid ; blue mould will appear, and a matting 

 of mycelium and spores will be seen. In the early stages of their 

 growth the mycelium takes the blue stain when iodine tincture 

 and sulphuric acid are placed over them. A power of 500 may be 

 used with profit when viewing these spores, although much lower 

 powers may be used for the amylaceous mycelium. Experiments of this 

 character will prepare the young investigator for detection of similar 

 bodies in other substances. 



On page 341, in the English Popular Science Review, Vol. vii, the 

 following appears upon starch in the yolk of the egg : " Our readers 

 will remember that we sometime since called attention to M. C. Dareste's 

 remarkable discovery of this fact. M. Dareste has since given a more 

 detailed account of his observations, and has described the means em- 

 ployed by him in isolating the starch-granules. First, he washes the 

 yolk rapidly with ether to remove the fatty matter. This should be 

 done quickly, so as to avoid coagulating the albuminous substances: 

 Then he washes it with water to remove albumen, sugar, and such 

 like matters. Finally, he treats the residue with acetic acid, an opera- 

 tion which extends over three months. During this time an extremely 



