camel-hair brush, like the leaves in the solution of camphor, but this
produced no effect.
* See Dr. M. Traube s curious experiments on the production of
artificial cells, and on their permeability to various salts, described
in his papers: Experimente zur Theorie der Zellenbildung und
Endosmose, Breslau, 1866; and Experimente zur physicalischen Erklrung
der Bildung der Zellhaut, ihres Wachsthums durch Intussusception,
Breslau, 1874. These researches perhaps explain my results. Dr. Traube
commonly employed as a membrane the precipitate formed when tannic acid
comes into contact with a solution of gelatine. By allowing a
precipitation of sulphate of barium to take place at the same time, the
membrane becomes infiltrated with this salt; and in consequence of
the intercalation of molecules of sulphate of barium among those of the
gelatine precipitate, the molecular interstices in the membrane are
made smaller. In this altered condition, the membrane no longer allows
the passage through it of either sulphate of ammonia or nitrate of
barium, though it retains its permeability for water and chloride of
ammonia. [page 217]
Nor did these four leaves, on being left for 24 hrs. in the diluted
alcohol, undergo any inflection. They were then removed; one being
placed in an infusion of raw meat, and bits of meat on the discs of the
other three, with their stalks in water. Next day one seemed a little
injured, whilst two others showed merely a trace of inflection. We
must, however, bear in mind that immersion for 24 hrs. in water
prevents leaves from clasping meat. Hence alcohol of the above strength
is not poisonous, nor does it stimulate the leaves like camphor does.
The vapour of alcohol acts differently. A plant having three good
leaves was left for 25 m. under a receiver holding 19 oz. with sixty
minims of alcohol in a watch-glass. No movement ensued, but some few of
the glands were blackened and shrivelled, whilst many became quite
pale. These were scattered over all the leaves in the most irregular
manner, reminding me of the manner in which the glands were affected by
the vapour of carbonate of ammonia. Immediately on the removal of the
receiver particles of raw meat were placed on many of the glands, those
which retained their proper colour being chiefly selected. But not a
single tentacle was inflected during the next 4 hrs. After the first 2
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