178 EXPERIMENTS WITH PLANTS 



of the gram and the intense brown or yellowish brown 

 of the peripheral layer. Place another section on a 

 slide, remove all superfluous moisture with blotting 

 paper, and place upon it a drop of a saturated solution 

 of cane-sugar in water. Then add a small drop of 

 chemically pure sulphuric acid (by means of a pipette 

 or medicine -dropper). Add a second drop of acid if 

 necessary ; use no cover-glass ; be careful that no acid 

 is spilled upon the microscope. Notice the bright red 

 color of the peripheral layer; this indicates the pres- 

 ence of proteid. The outer peripheral layer is much 

 richer in proteid than the rest of the grain: owing to 

 its dark color it is considered undesirable for flour and 

 is separated from the rest of the grain in milling, 

 forming the bran, so that ordinary Wheat flour consists 

 of the internal part of the grain only. As the bran 

 forms about one-fifth of the grain, this is a wasteful 

 process. Whole Wheat flour contains the bran as well 

 as the inner portion and is not only more nutritious 

 but more easily digested and more healthful in other 

 respects. Find out what you can about the process of 

 milling and the use of flour in bread, etc.^ 



Note the great difference between the seed-leaves of 

 the Horse-bean (Fig. 2) and the Castor-bean (Fig. 4). 

 Can you explain this difference of structure on the 



1 See Johnson, "Chemistry of Common Life," Chap. V ; Williams, "Chem- 

 istry of Cookery," Chap. XH ; Williams and Fisher, "Theory and Practice of 

 Cookery." Also an article by Snyder and Woods in the Year-Book of the U. S. 

 Dept. of Agriculture, for 1903. 



