196 The Microscope. v 



parenchymal cells are slightly smaller and more compacted around 

 the oleo-resin cells, but do not differ otherwise from the remainder 

 of the parenchyma. 



Fig. 4b, Parenchymal Cells. 4c, Outer Layer of Cells. 



The cells of the parenchyma do not ordinarily exhibit any 

 formed starch, but the elements of starch are contained in the cells, 

 for upon chemical analysis of the meal in quantity the presence of 

 starch is indicated, and a fine granular matter with which the cells 

 of the parenchyma are filled, shown in portions only of Fig. 4, is 

 undoubtedly of an amylaceous character. Iodine does not give a 

 distinct reaction, indicating starch. 



Fig. 4d, Granules. 



The oleo-resin glands, or cells, are composed of a thin -walled 

 cell of structureless membrane, and are tilled with a dark reddish 

 oil, holding in solution a small percentage of resin and a minute 

 quantity of an essential oil. The contents of these oleo-resin 

 glands constitutes the cottonseed oil of commerce, a product which 

 has caused as great a revolution in the oil trade as the fibre of the 

 seed caused in that of textile fabiics, so that twice in the world's 

 history its commerce has been fundamentally affected by the pi'oduct 

 of a single plant, whose product in each case supplanted those of 

 a number of other sources of supply. 



Microscopical examination of the oil itself reveals nothing, but 

 the separated stearic matter which settles in the more viscous of the 

 refined oils is found to be composed of fine acicular crystals, 

 cohering in [burr-like masses, very similar to but less dense than 

 those of lard. 



Fig. •"). Crystals. 



The solid fatty acids of the oil resemble those of animal fats 

 and are beautiful objects by polarized light, crystallizing in irregu- 

 lar plates, curiously interlaced and matted together. 



The microscopical structure of the cotton fibre is so well 

 known to all microscopists as to jirohibit description here. The 

 lint remaining on the seed after ginning is the remnant of the fibre 

 and has the same structure. In the manufacture of the oil, the 

 first process to which the cleaned seed is subjected to is " linting," 

 which consists in passing it through a specially constructed saw 

 gin, or "linter," by which almost all of the lint is removed, forming 

 a short, staple, light lint fibre, called "re-gins," which forms a 

 paper stock of the highest quality. A lower grade of paper stock 

 is made from the hulls, which are easily reduced to fibre, and is 



