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1903] CURRENT LITERATURE 157 
immediately upon treatment with weak chloroform-water reacted positively. 
n other words, the critical intensity of light (z. ¢., the point at which a given 
organism will not react) was raised by the chloroform, so that what they fled 
from before, they now sought. This effect disappears gradually, and the 
faster the weaker the chloroform. Ether produces no such effect. Imme- 
diately after a phototactic organism recovers from a dose of ether or chloro- 
form, its reaction is always negative. If normally positive, the reaction is 
reversed ; if normally negative, the reaction is intensified; 7. ¢., the critical 
intensity of light is lowered. 
The results reached by Rothert regarding the specifically different sus- 
ceptibility of related forms to narcosis are quite irreconcilable with the 
Statements of Overton, who holds* that this susceptibility depends on the 
grade of differentiation of the cells, as indicated by the rank of the organism. 
Even individual differences were found by Rothert to be great 
It is found to be characteristic of the anesthetic effect of ether and 
chloroform on microorganisms that it depends only upon their concentration 
. and not upon the duration of their action. Anesthesia appears instantly and 
disappears as quickly. No solution which is too weak to effect anesthesia at 
once will produce it by prolonged action. Some observations indicate that 
solutions too weak to produce complete anesthesia will diminish the degree of 
sensitiveness to stimuli. The effect of these narcotics on movement, however, 
is quite different; for this depends both on their concentration and the dura- 
tion of their action. 
This paper adds valuable data to our present knowledge of the narcosis in 
plants, for which previously we have been chiefly indebted to Overton. 
ok. 
24 Studien iiber die Narkose. Jena. 190I. 
