126 DROSERA ROTUNDIFOLIA. Cuar. VI 
used, as well as some freshly prepared, with artificial digestive 
liquid, and found that it was not digested. Dr. Lauder Brunton 
likewise tried some prepared by the process given in the British 
Pharmacopveia, and exposed it for five days at the temperature 
of 37° Cent. to digestive liquid, but it was not diminished in 
bulk, though the fluid acquired a slightly brown colour. It was 
also tried with the glycerine extract of pancreas with a negative 
result. Nor does chlorophyll seem affected by the intestinal 
secretions of various animals, judging by the colour of their 
excrement. 
It must not be supposed from these facts that the grains of 
chlorophyll, as they exist in living plants, cannot be attacked by 
the secretion; for these grains consist of protoplasm merely 
coloured by chlorophyll. My son Francis placed a thin slice of 
spinach leaf, moistened with saliva, on a leaf of Drosera, and 
other slices on damp cotton-wool, all exposed to the same 
temperature. After 19 hrs. the slice on the leaf of 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 in- 
flected 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 Otl.—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 
inflection, and the leaves did not re-expand until the fourth 
day; but I have no doubt that 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: 
