264 BACTERIOLOGICAL METHODS 



position wholly for itself. For the results of narcotic experiments which have been 

 obtained with essential oils in the case of coid-blooded animals and in that of the higher 

 plants are altogether different from those which have been obtained with bacteria. 



The results of narcotic experiments with fishes and tadpoles, of respiration 

 experiments with toads and of injection experiments with frogs are reproduced in 

 the form of tables arranged according to the degree of activity of the essential oils. 



For the purpose of testing narcotic action on fishes, roaches (Leuciscus rutilus} were 

 used. The limit of concentration taken was the dilution which produced perceptible 

 narcosis in the fish within a period of 24 hr., that is to say, a condition when the 

 animal, without displaying much spontaneous motion, floated in the water in an 

 atactic condition and altogether failed to respond to squeezing with hooked pincers. 

 Only those experiments were regarded as affording proof in which the fish recovered 

 when replaced in fresh water. 



Fof the purpose of estimating the antiseptic action, Geinitz added in each case 

 to 10 cc. of fresh milk, placed in a test-tube of 16 to 18 cc. capacity, first as much 

 Sulphur depuratum as would lie on the point of a knife, and afterward the antiseptic. 

 After vigorous shaking a piece of filtering paper soaked with solution of lead acetate 

 was hung up in the upper part of the test-tube hi such a way as not to come in contact 

 with the milk, and the test-tube was closed with a wad of cotton-wool. The tubes 

 were then kept 24 hr. in a water plug bath at about 38 C. If, after that lapse of 

 time, the lead paper was found to be blackened, it was evident that the tube in 

 question did not contain a sufficient proportion of the antiseptic. As a series of test- 

 tubes was always being treated with an increasing quantity of antiseptic, it was easy 

 to determine exactly when the limit of concentration was reached at which the activ- 

 ity of the bacteria was impeded. 1 



EXPERIMENTS IN NARCOSIS, MADE ON FISHES 



1 Abstracted from the Sitzungsberichte und abhandlungen der naturforschenden 

 Gesellschaft zu Rostock, New Series, Vol. IV, 1912. Rostock, 1913. The paper was 

 awarded a prize. 



The evolution of sulphuretted hydrogen from milk diluted with sulphur is due to 

 bacterial action. 



