224 BOTANICAL GAZETTE [ MARCH 
these structures better adapted to their purpose than the vegetating cells. 
Exposure of the bacteria to the action of the desired chemical is made by 
immersing in a solution of definite strength small garnets of uniform size that 
have previously been coated with a film of an infected solution. Aftera 
definite exposure, these are removed and replaced in nutrient media. The 
intensity of chemical action is noted by the development of the cultures. 
The explanations that have been offered to account for the action of dif- 
ferent chemicals upon living matter have been far from satisfactory. The 
whole subject is in a chaotic state, and while we possess sufficient empirical 
knowledge to enable us to arrange chemical substances in order of their effec- 
tiveness, no underlying principle has yet been brought to light that coordi- 
nates the enormous mass of facts that have been collected within recent years. 
While in strong solutions it is undoubtedly true that the destructive effect of 
certain chemical substances is due to their corrosive or oxidizing properties, 
whereby the protoplasm is actually destroyed, there can no longer be any 
doubt, from the results here obtained, that in dilute solutions, the action of 
the molecule is largely dependent upon the dissociation that it undergoes in the 
solution. Paul and Krénig find by using solvents such as ether and absolute 
alcohol that do not permit dissociation of the salt into its constituent ions, 
that its toxic effect is slight; whereas if the salt is separated into the basic 
and acid ions, even in part, as in dilute watery solutions, its action is much 
more marked. In a number of instances where the disinfecting effect of a 
salt is diminished by the addition of other substances, as HgCl, in contact 
with NaCl, they find the explanation of these results in the formation of com- 
plex ions in which the actively disinfecting ion is not free to exert its toxic 
effect. Thus, while silver and gold salts, as AgNO; and HAuCl, are power- 
ful germicides, their action is greatly weakened when mixed with KCy. 
_ The remarkable observation made by Scheurlen® that the effect of phenol 
is increased by adding such a salt as NaCl, they are able to confirm, but, in 
the light of this theory, they are unable to explain it. The application of 
this new theory to the action of chemical substances on bacteria is most sug- 
gestive as it eas a large mass of isolated facts under the operation of a 
general law.— H. L. Russet. 
_ THE ORGANIC NUTRITION of green plants has just been considered by Th. 
Bokorny.” Hes 's that the ability of fungi to use organic food is not to 
be considered ia to them. We know that many cells in a green. plant 
are always nourished with organic substances. Only in the leaves and a 
small part of the stem is chlorophyll present and only in these parts can CO2 
9 Die Bedeutung d. —— d. wassergelisten Desinfektionsmittel f- 
ihren Wirkungswert. Strassburg, 189 
> Ueber die organische ar pe — und ihre Bedeutung in der 
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