126 DROSERA ROTUNDIFOLIA. CHAT. 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 

 Pharmacopoeia, 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. 



Fut 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 an> 

 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. Eather 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 : 



