244 WM. L. OWEN 



stool, may have accounted for the negative results of the inocula- 

 tion experiments. It is likely, however, that B. saccharalis does 

 not induce any marked deterioration of the juice of growing 

 cane, and indeed the apparently negative results which indicated 

 a higher purity in the inoculated canes is well within the range 

 of possible results from the action of the species. We have 

 seen in the experiment on the action of this species upon cane 

 juice how an increase of the purity of the juice may result from 

 the fermentation of the invert sugar. It seems very probable 

 that a similar result might follow from the presence of the species 

 in growing cane. The occurrence of B. saccharalis in borer in- 

 fested cane, and its survival in the interior of cane artificially 

 inoculated with it, suggests a certain ability on its part to pro- 

 tect itself against the defensive properties of the plant. Sugar 

 cane, hke all other plants, possesses protective enzymes which 

 tend to prevent the invasion of its tissues with organisms and 

 their development therein, once they succeed in gaining an 

 entrance. Browne (1906) reports a distinctly germicidal property 

 of freshly extracted cane juice. He says: 



The darkening of vegetable tissues on the exposure to the air has 

 been explained by Bertrand, to be due to the action of an oxidizing 

 enzjTne upon various tannin bodies, all more or less related to the 

 polyphenols, and the query naturally arises does cane juice itself 

 exercise any germicidal properties in connection with the natural 

 phenomenon of darkening. The conclusion which we have reached 

 in investigating this point is that cane juice does acquire for a time 

 such germicidal characteristics. Counting the bacteria in the expressed 

 juice of the cane at regular periods usually shows for several hours a 

 uniform decrease in numbers; with juice from sterilized canes on the 

 other hand, the bacterial content increases from the very start. 



Again the author referred to states, that 



The Hving plant therefore does appear to protect itself against the 

 invasion of microscopic parasites by forming toxic products. 



The relation between the germicidal power of cane juice and 

 the enzymes it contains, is suggested in the following obser- 

 vation by Browne, viz., 



