Onar. V1, DIGESTION. 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 interest- 
ing 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 in- 
flected for a longer time, than does gelatine, or 
* See the classifidation adopted by Dr. Michael Foster in Watts’ 
Dict. of Chemistry,’ Supplement 1872, p. 969. 
