Cdap. XV.] ABSORPTION. 275 



Other leaves were placed in a weak infusion of raw meat and 

 in human saliva, and the glands were much darkened in 25 

 m., and after 40 m. were so dark as almost to deserve to be 

 called black. Even immersion for a whole day in distilled 

 water occasionally induces some aggregation within the 

 glands, so that they become of a darker tint. In all these 

 cases the glands are affected in exactly the same manner 

 as those of Drosera. Milk, however, which acts so ener- 

 getically on Drosera, seems rather less effective on Drosophyl- 

 lum, for the glands were only slightly darkened by an im- 

 mersion of 1 hr. 20 m., but became decidedly darker after 

 3 hrs. Leaves which had been left for 7 hrs. in an infusion 

 of raw meat or in saliva were placed in the solution of car- 

 bonate of ammonia, and the glands now became greenish; 

 whereas, if they had been first placed in the carbonate, they 

 would have become black. In this latter case, the ammonia 

 probably combines with the acid of the secretion, and there- 

 fore does not act on the colouring matter; but when the 

 glands are first subjected to an organic fluid, either the acid 

 is consumed in the work of digestion or the cell-walls are 

 rendered more permeable, so that the undecomposed carbon- 

 ate enters and acts on the colouring matter. If a particle 

 of the dry carbonate is placed on a gland, the purple colour 

 is quickly discharged, owing probably to an excess of the 

 salt. The gland, moreover, is killed. 



Turning now to the action of organic substances, the 

 glands on which bits of raw meat were placed became dark- 

 coloured; and in 18 hrs. their contents were conspicuously 

 aggregated. Several glands with bits of albumen and fibrin 

 were darkened in between 2 hrs. and 3 hrs.; but in one case 

 the purple colour was completely discharged. Some glands 

 which had caught flies were compared with others close by; 

 and though they did not differ much in colour, there was a 

 marked difference in their state of aggregation. In some 

 few instances, however, there was no such difference, and 

 this appeared to be due to the insects having been caught 

 long ago, so that the glands had recovered their pristine 

 state. In one case, a group of the sessile colourless glands, 

 to which a small fly adhered, presented a peculiar appear- 

 ance; for they had become purple, owing to purple granular 

 matter coating the cell-walls. I may here mention as a 

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