328 ANNUAL REPORT OF THE Off. Doc. 



starch is being elaborated. Many trees store up during the winter 

 reserve material in the form of starch which becomes food for un- 

 folding buds on the advent of spring. Thus Desbarres^* found in the 

 young wood of Bhus elegans 17.31 per cent, of starch during the 

 winter and only 1.57 in the spring. 



The sugar maple yields in the early spring a sweetish sap which is 

 produced from the reserve starch accumulated in the wood during 

 the preceding fail. 



Many roots and tubers are notable for their large content of 

 starch, which, in all biennial plants, serves as food for a second 

 season's growi:h. When potatoes sprout they draw largely upon the 

 starch of the tuber, and with the elongation of the sprouts we note 

 a dimunition of the starch and an increase of sugar. With this there 

 is an accumulation of diastase in the tuber at the points where the 

 sprouts originate. 



In refering to the fermentation of cellulose, it was stated that it is 

 a common function of many enzymes, of which diastase is one, to ef- 

 fect the hydration of certain organic substances, or their union with 

 water. 



The hydration, or conversion of starch into sugar, is a complex pro- 

 cess, not as yet altogether understood, but the two products of the 

 change are evidently maltose and dextrin. It can perhaps be ex- 

 pressed according to Musculus^^ by the following: 



2 Ci2 H20 Oio H2 O C12 H22 On C12 H20 Oio 



+ = + — 



starch water maltose dextrin 



Dextrin, which is a residual product of the partial hydration of 

 starch does not, however, remain as such, but is eventually converted 

 into maltose. 



When vegetable materials are incorporated with the soil, it is not 

 likely that bacteria play a very important role in the conversion of 

 this contained starch into sugar. On the other hand the change is 

 likely brought about by diastases normally present in the plants 

 themselves, and the greater part of this transformation is effected 

 before bacteria have time to reach the starchy materials within the 

 cells. Thus in the decomposition of vegetable matter in the soil, 

 much at least of the fermentation of starch is a process quite inde- 

 jiendent of the action of bacterial life. This does not indicate, how- 

 ever, that certain bacteria and fungi are not capable of effecting this 

 change, in fact Fermi^ has shown that a considerable number of bac- 

 teria secrete diastatic enzymes, notably, Bacillus megathet'ium^ 

 Bacillus, m •'• nt ri u -v}/ g us and B cHlus subtilis, forms com- 

 monly present in the soil; and it is likely that a residual portion of 

 unchanged starch may be acted upon by such organisms, though this 



