104. DROSERA ROTUNDIFOLIA. [Cuap. VL 
slice on the leaf of the Drosera was bathed in much’ secretion from 
the inflected tentacles, and was now examined under the microscope. 
No perfect grains of chlorophyll could be distinguished; some were 
shrunken, of a yellowish-green colour, and collected in the middle of 
the cells; others were disintegrated and formed a yellowish mass, 
likewise in the middle of the cells. On the other hand, in the 
slices surrounded by damp cotton-wool, the grains of chlorophyll were 
green and as perfect as ever. My son also placed some slices in 
artificial gastric juice, and these were acted on in nearly the same 
manner as by the secretion. We have seen that bits of fresh cabbage 
and spinach leaves cause the tentacles to be inflected and the glands 
to pour forth much acid secretion; and there can be little doubt that 
it is the protoplasm forming the grains of chlorophyll, as well as that 
lining the walls of the cells, which excites the leaves. 
fat and Oil.—Cubes of almost pure uncooked fat, placed on several 
leaves, did not have their angles in the least rounded. We have also 
seen that the oil-globules in milk are not digested. Nor does olive oil 
dropped on the discs of leaves cause any inflection; but when they 
are immersed in olive oil they become strongly inflected; but to this 
subject I shall have to recur. Oily substances are not digested by 
the gastric juice of animals. 
Starch.—Rather large bits of dry starch caused well-marked in- 
flection, and the leaves did not re-expand until the fourth day; but I 
have no doubt tbat this was due to the prolonged irritation of the 
glands, as the starch continued to absorb the secretion. The particles 
were not in the least reduced in size; and we know that leaves 
immersed in an emulsion of starch are not at all affected. I need 
hardly say that starch is not digested by the gastric juice of animals. 
Action of the Secretion on Living Seeds. 
The results of some experiments on living seeds, selected by hazard, 
may here be given, though they bear only indirectly on our present 
subject of digestion. 
Seven cabbage seeds of the previous year were placed on the same 
number of leaves. Some of these leaves were moderately, but the 
greater number only slightly inflected, and most of them re-expanded. 
on the third day. One, however, remained clasped till the fourth, and 
another till the fifth day. ‘These leaves therefore were excited some- 
what more by the seeds than by inorganic objests of the same size. 
After they re-expanded, the seeds were placed under favourable con- 
ditions on damp sand; other seeds of the same lot being tried at the 
same time in the same manner, and found to germinate well. Of the 
seven seeds which had been exposed to the secretion, only three ger- 
minated ; and one of the three seedlings soon perished, the tip of its 
radicle being from the first decayed, and the edges of its cotyledons of 
a dark brown colour; so that altogether five out of the seven seeds 
ultimately perished, 
