No. 6. DEPARTMENT OF AGRICULTURE. 329 



statement will require experimental proof. It is also known that cer- 

 tain common moulds, for example, Pennicil'mm glaucum., Aspergil- 

 lus niger and Erotlum oryzae^ possess the power of converting starch 

 into sugar. 



As already mentioned, the action of diastase upon starch consists 

 in its conversion into maltose and dextrin, but maltose has only a 

 temporary existence in the animal and plant organism, since it is 

 acted upon by another enzyme known as glucase^ which further 

 hydrolases the maltose converting it into glucose. Thus glucose 

 is the final product of the fermentation of starch. 



Glucase is present in the digestive fluids of the human body. It 

 has been found in corn and malt, and in several species of fungi. 

 That it probably exists in association with diastase in plant tissues is 

 made probable by the fact that maltose as such is unable to nourish 

 growing cells. 



(5) The Inversion of Cane Sugar. — When a solution of cane sugar is 

 boiled with a dilute acid it undergoes an hydrolysis by which it is 

 converted into glucose and levule-^i according to the equation.: 



Ci2 H22 On H2 O Gi H12 0« Cs H12 0« 



+ — + 



cane sugar water glucose levulose 



That the same change can be effected through the agency of an 

 enzyme has been known ever since the latter was first isolated from 

 yeast in ISGO by Berthelot.^^ This enzyme is known is invertin. It 

 has also been found in the intestinal juices of man and a number 

 of animals, and from various parts of plants as leaves, seeds, roots 

 and floral organs. 



Cane sugar is found often in considerable amounts in plant tis- 

 sues, and yet as such it is of no direct use as a plant nutrient, but 

 must first be digested or converted into glucose. Thus the beet 

 may contain 15 per cent, of cane sugar. When, however, the latter is 

 drawn upon for the production of flowers and seeds during the second 

 year's growth it has been noted that its content of cane sugar gradu- 

 ally diminishes and glucose takes its place, the latter being traced 

 in its ascent from the root to the developing leaves and flowers. 

 Thus the presence of cane sugar in the plant implies the existence 

 at the same time of invertin. The first step therefore in the fermen- 

 tation of cane sugar is its conversion into glucose through the agency 

 of its associated invertin. 



This change like the action of diastase is also one which takes place 

 in the soil independent, in a large measure at least, of bacterial 

 action. 



According to Fermi^i and Montesano the production of invertin 

 enzymes by bacteria is uncommon, although certain prevalent soil 



