TEH WORK OF LEAVES 177 



proteid, the yolk is largely fat and oil. The egg 

 (minus the shell) contains about 14 per cent of pro- 

 teid and 13 of fat; this is a higher percentage of 

 proteid than most seeds possess, but Peas, Beans, 

 etc., contain as much as 24 per cent of proteid: in 

 oily seeds, fat may be present to the amount of 60 

 per cent. 



Of especial interest is the composition of Grains; 

 as an example of these we may take Wheat. Moisten 

 some ordinary Wheat flour with water and place it 

 in a muslin bag. Allow a stream of water to run 

 slowly through the bag while the dough is kneaded 

 with the fingers. Collect the milky fluid which runs 

 through the cloth: this contains the starch, which 

 gradually settles to the bottom. When the starch is 

 all removed there remains behind a mass which, from 

 its glutinous consistency, is called gluten: this is the 

 proteid of the Wheat (apply the proteid tests to it). 

 It forms about 10 per cent of the flour, while the 

 starch forms about 75 per cent. 



Take some grains of Wheat which have been suffi- 

 ciently softened in water (a few minutes suffices in hot 

 water) to cut easily, and with a razor cut thin slices 

 across the grain. Place some of these in a drop of 

 water on a glass slide, cover with a cover-glass, and 

 examine with the low power of the microscope. Re- 

 move the cover-glass and add a drop of iodine solu- 

 tion. Notice the blue-black color of the internal part 



