The grains being then removed, and examined under the microscope, were found discoloured, with the oil-globules remarkably aggregated.  Many had their contents much shrunk, and some were almost empty.  In only a few cases were the pollen-tubes emitted.  There could be no doubt that the secretion had penetrated the outer coats of the grains, and had partially digested their contents.  So it must be with the gastric juice of the insects which feed on pollen, without masticating it.* Drosera in a state of nature cannot fail to profit to a certain extent by this power of digesting pollen, as innumerable grains from the carices, grasses, rumices, fir-trees, and other wind-fertilised plants, which commonly grow in the same neighbourhood, will be inevitably caught by the viscid secretion surrounding the many glands.

Gluten.—­This substance is composed of two albuminoids, one soluble, the other insoluble in alcohol.  Some was prepared by merely washing wheaten flour in water.  A provisional trial was made with rather large pieces placed on two leaves; these, after 21 hrs., were closely inflected, and remained so for four days, when one was killed and the other had its glands extremely blackened, but was not afterwards observed.

* Mr. A.W.  Bennett found the undigested coats of the grains in the intestinal canal of pollen-eating Diptera; see ’Journal of Hort.  Soc. of London,’ vol. iv. 1874, p. 158.

  Watts’ ‘Dict. of Chemistry,’ vol. ii. 1872, p. 873. [page 118]

Smaller bits were placed on two leaves; these were only slightly inflected in two days, but afterwards became much more so.  Their secretion was not so strongly acid as that of leaves excited by casein.  The bits of gluten, after lying for three days on the leaves, were more transparent than other bits left for the same time in water.  After seven days both leaves re-expanded, but the gluten seemed hardly at all reduced in bulk.  The glands which had been in contact with it were extremely black.  Still smaller bits of half putrid gluten were now tried on two leaves; these were well inflected in 24 hrs., and thoroughly in four days, the glands in contact being much blackened.  After five days one leaf began to re-expand, and after eight days both were fully re-expanded, some gluten being still left on their discs.  Four little chips of dried gluten, just dipped in water, were next tried, and these acted rather differently from fresh gluten.  One leaf was almost fully re-expanded in three days, and the other three leaves in four days.  The chips were greatly softened, almost liquefied, but not nearly all dissolved.  The glands which had been in contact with them, instead of being much blackened, were of a very pale colour, and many of them were evidently killed.