Cuap. YI. DIGESTION. 117 
The slices were not liquefied, for the walls of the cells, 
composed of cellulose, are not in the least acted on 
by the secretion. 
Pollen —A little fresh pollen from the common pea 
was placed on the discs of five leaves, which soon 
became closely inflected, and remained so for two or 
three days. 
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 albu- 
minoids, one soluble, the other insoluble in alcohol.f 
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 foundthe Hort. Soc. of London,’ vol. iv, 
undigested coats of the grainsin 1874, p. 158. 
the intestinal canal of pollen- t Watts’ ‘ Dict. of aia 
eating Diptera; see ‘Journal of vol. ii. 1872, p. 873. 
