BY R. r.RKIG-SMITH. 



85 



crude, was unaltered, and the same was the case with the second 

 test of E . polybractea, rect. The higher acidification of E. dives, 

 crude, gave an enhanced effect, and it seemed as if the slightly 

 higher acidity of the altered E. polybractea might have been 

 responsible for the increased activity of the oil. With the 

 phellandrene oil of E. dives, the increase of the toxicity took 

 place at once, while it was slowly developed in the Essential Oil 

 and in E. polybractea. The irregular behaviour of the oils led to 

 a further test, in which progressive amounts of acid were added. 



Table v. — M. aureus. 



000- inactive. 



In this experiment, cineol and E. polybractea, rect., were not 

 affected by the addition of considerable amounts of acetic acid. 

 E. cinerea, crude, did have its germicidal activity increased, but 

 not definitely in proportion to the acid added. 



The two experiments are at variance, and there is apparently 

 some unknown condition, which regulates the action of the acid 

 in producing bactericidal substances in the oils. 



The acid itself must have a certain germicidal action, and 

 several tests were made to see how much was necessary to pro- 

 hibit growth under the conditions of the previous experiments. 

 A quantity of olive oil was acidified with glacial acetic acid, and 

 dilutions of this were made with the neutral oil. 



