(35) 



Starches. Case 69. — Starch is largely formed by most 

 plants, as a reserve food supply, from the water taken in 

 through the roots and the carbonic acid gas inhaled from 

 the atmosphere; the chemical combination is effected by 

 the sun's energy, directed by the green coloring matter 

 (chlorophyl). Starch is mostly found in the form of 

 granules, sometimes in small rods, and is easily converted 

 by the plant, or artificially, into glucose, in which form 

 the plant consumes it. In darkness the plant consumes 

 starch previously formed in daylight. Starch is insoluble 

 in water and can therefore be easily washed out from ground 

 plant tissue. The forms of the starch grains are so con- 

 stant and characteristic in each plant that they afford an 

 excellent method of identifying the latter, even in powder. 

 Starch, as in the case of many other substances, exists in 

 and is consequently derived from the several organs of 

 various plants, for example, the roots of the cassava plant 

 furnish the cassava flour and tapioca, while those of coontie 

 yield coontie floor or Florida-arrowroot which is quite 

 similar to sago, and those of the sweet-potato plant furnish 

 sweet-potato flour. The rootstocks of the common potato 

 plant abound in potato-flour, while those of the arrowroot 

 plant yield arrowroot flour. The stems of some of the 

 sago palms and those of some of the true palms are the 

 sources of sago flour. The fruits, both dry and fleshy, of a 

 great variety of plants, contain starch; for example, those 

 of the several grains, wheat, rye, and corn; while those of 

 the banana yield the less common banana flour. The 

 seeds of some plants are used as a source of starch, as for 

 instance, those of the chocolate plant. 



Cork and Paper. Cases 70 and 72. Cork forms the 

 outer portion of the bark of most woody stems. That of 

 one species of oak, Quercus Suber, of the Mediterranean 

 region, possesses peculiar properties of toughness, elas- 

 ticity, and imperviousness to liquids and vapors which 

 makes it useful for bottle stoppers. Many attempts have 

 been made to find substitutes, but none have been found 



