DIGESTION OF CELLULOSE 269 



the endosperm. Test both layers for proteids (see Zimmerman's 

 Botanical Microtechnique). Germinate some of the seeds and 

 after the roots are a centimeter in length cut sections as before. 

 The germination should be carried on in a thermostat at a tem- 

 perature of at least 22 C. or perhaps 30 C. Compare the ap- 

 pearance and structure of the secreting layers with that of the 

 resting seed, and look for changes in the contents of the cells 

 near them. 



341. Action of Secretion from Scutellum on Starch. Grate the 

 white portion of a potato finely, and fill the cavity in a dozen cul- 

 ture slides. Carefully dissect out the embryos of an equal num- 

 ber of seeds of corn that have laid between folds of damp cloth, 

 or in a germinator, for two days. Lay one of these embryos 

 with the scutellum downward in each of the masses of grated 

 potato in the slides, and put all of the preparations in a moist 

 chamber at a temperature of 40 C. Fill one of the slides with 

 grated potato only and also lay in moist chamber. Examine the 

 grated potato with the microscope and note the appearance of 

 the starch grains. Test with iodine, and note exact color reac- 

 tion. Test the grated material for sugar with Fehling's solution 

 (220). Now institute a series of tests at intervals of an hour, to 

 ascertain the beginning, and course of the hydrolysis of the starch. 

 This will be indicated by a change in the color reaction with 

 iodine, due to the intermediate products, and no color reaction 

 will be given after all of the starch has been converted into mal- 

 tose. Test final solution for sugar with Fehling's solution. Cut 

 sections of a seed attached to young plantlets of corn and note 

 the different staining reactions with iodine. 



342. Digestion of Cellulose. Cellulose walls of cells are in 

 reality made up of quite a number of substances including some 

 pectoses. The digestion of the celluloses appears to be accom- 

 plished by cytase and other enzymes. The process is one of 

 hydrolyzation and some form of sugar is the principal product. 

 Cytase is probably most active at a temperature of 35-40 C., 

 and is destroyed at 70 C. It is formed by seeds, and is espe- 



