(7) Fibrin excites less secretion than does meat or albumen.  Several trials were made, but I will give only three of them.  Two minute shreds were placed on some glands, and in 3 hrs. 45 m. their secretion was plainly increased.  The smaller shred of the two was completely liquefied in 6 hrs. 15 m., and the other in 24 hrs.; but even after 48 hrs. a few granules of fibrin could still be seen through a lens floating in both drops of secretion.  After 56 hrs. 30 m. these granules were completely dissolved.  A third shred was placed in a little pool of secretion, within the margin of a leaf where a seed had been lying, and this was completely dissolved in the course of 15 hrs. 30 m.

(8) Five very small bits of gluten were placed on a leaf, and they excited so much secretion that one of the bits glided down into the marginal furrow.  After a day all five bits seemed much reduced in size, but none were wholly dissolved.  On the third day I pushed two of them, which had begun to dry, on to fresh glands.  On the fourth day undissolved traces of three out of the five bits could still be detected, the other two having quite disappeared; but I am doubtful whether they had really been completely dissolved.  Two fresh bits were now placed, one near the middle and the other near the margin of another leaf; both excited an extraordinary amount of secretion; that near the margin had a little pool formed round it, and was much more reduced in size than that on the blade, but after four days was not completely dissolved.  Gluten, therefore, excites the glands greatly, but is dissolved with much difficulty, exactly as in the case of Drosera.  I regret that I did not try this substance after having been immersed in weak hydrochloric acid, as it would then probably have been quickly dissolved.

(9) A small square thin piece of pure gelatine, moistened with water, was placed on a leaf, and excited very little secretion in 5 hrs. 30 m., but later in the day a greater amount.  After 24 hrs. the whole square was completely liquefied; and this would not have occurred had it been left in water.  The liquid was acid.

(10) Small particles of chemically prepared casein excited [page 384] acid secretion, but were not quite dissolved after two days; and the glands then began to dry.  Nor could their complete dissolution have been expected from what we have seen with Drosera.

(11) Minute drops of skimmed milk were placed on a leaf, and these caused the glands to secrete freely.  After 3 hrs. the milk was found curdled, and after 23 hrs. the curds were dissolved.  On placing the now clear drops under the microscope, nothing could be detected except some oil-globules.  The secretion, therefore, dissolves fresh casein.