over large bits or large drops than over small bits or drops. Texture
probably plays a part in determining the extraordinary length of time
during which the tentacles remain inflected [page 133] over the hard
grains of chemically prepared casein. But the tentacles remain
inflected for an equally long time over finely powdered, precipitated
phosphate of lime; phosphorus in this latter case evidently being the
attraction, and animal matter in the case of casein. The leaves remain
long inflected over insects, but it is doubtful how far this is due to
the protection afforded by their chitinous integuments; for animal
matter is soon extracted from insects (probably by exosmose from their
bodies into the dense surrounding secretion), as shown by the prompt
inflection of the leaves. We see the influence of the nature of
different substances in bits of meat, albumen, and fresh gluten acting
very differently from equal-sized bits of gelatine, areolar tissue, and
the fibrous basis of bone. The former cause not only far more prompt
and energetic, but more prolonged, inflection than do the latter. Hence
we are, I think, justified in believing that gelatine, areolar tissue,
and the fibrous basis of bone, would be far less nutritious to Drosera
than such substances as insects, meat, albumen, &c. This is an
interesting conclusion, as it is known that gelatine affords but little
nutriment to animals; and so, probably, would areolar tissue and the
fibrous basis of bone. The chondrin which I used acted more powerfully
than gelatine, but then I do not know that it was pure. It is a more
remarkable fact that fibrin, which belongs to the great class of
Proteids,* including albumen in one of its sub-groups, does not excite
the tentacles in a greater degree, or keep them inflected for a longer
time, than does gelatine, or
* See the classification adopted by Dr. Michael Foster in Watts
Dictionary of Chemistry, Supplement 1872, page 969. [page 134]
areolar tissue, or the fibrous basis of bone. It is not known how long
an animal would survive if fed on fibrin alone, but Dr. Sanderson has
no doubt longer than on gelatine, and it would be hardly rash to
predict, judging from the effects on Drosera, that albumen would be
found more nutritious than fibrin. Globulin likewise belongs to the
Proteids, forming another sub-group, and this substance, though
containing some matter which excited Drosera rather strongly, was
hardly attacked by the secretion, and was very little or very slowly
116