THE SEED 



M. 



minating grains of barley, wheat, corn, rice, etc. By the 

 presence of diastase starch is converted into grape sugar, a 

 substance which is readily soluble in water, and which can 

 be diffused easily through the tissues of the plant to any 

 part where it is needed. In this way food travels from the 

 leaf, where it is made, to 

 the seed, where the sugar is 

 generally reconverted into 

 starch and stored up for 

 future use, though some- 

 times, as in the sugar corn 

 and sugar pea, it remains 

 in part unchanged. The 

 kernels of this kind of corn 

 can be distinguished readily 

 from those of the ordinary 

 starch corn, after maturity, 

 by their wrinkled appear- 

 ance, owing to their greater 

 loss of water in drying. 



10. Food tests. In or- 

 der to tell whether any of 

 the food substances named 

 occur in the seeds that we are going to examine, it will be 

 necessary to understand a few simple tests by which their 

 presence may be recognized. The chemicals required can 

 be ordered ready for use from a druggist or may be prepared 

 in the laboratory as needed, according to the directions 

 given. Write in your notebook a brief account of each ex- 

 periment made, with the conclusions drawn from it. 



EXPERIMENT 1 . To DETECT THE PRESENCE OF FATS. Rub a small lump 

 of butter or a drop of oil on a piece of thin white paper. What is the effect ? 



EXPERIMENT 2. ANOTHER TEST FOR FATS. Place some macerated 

 alcanna root in a vessel with alcohol enough to cover it, and leave for an 

 hour. Add an equal bulk of water and filter. The solution will stain 

 fats, oils, and resins deep red. 



FIG. 12. Starch grains of wheat in 

 different stages of disintegration under the 

 action of a ferment (diastase), accompany- 

 ing germination : a, slightly corroded ; b, c, 

 and d, more advanced stages of decomposi- 

 tion. 



