CHAP. XV. DIGESTION. 339 



fluid, either the acid is consumed in the work of di- 

 gestion or the cell- walls are rendered more permeable, 

 so that the undecomposed carbonate 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 con- 

 tents 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 appearance ; 

 for they had become purple, owing to purple granular 

 matter coating the cell-walls. I may here mention 

 as a caution that, soon after some of my plants arrived 

 in the spring from Portugal, the glands were not 

 plainly acted on by bits of meat, or insects, or a 

 solution of ammonia a circumstance for which I 

 cannot account. 



Digestion of Solid Animal Matter. - - Whilst I was 

 trying to place on two of the taller glands little cubes 

 of albumen, these slipped down, and, besmeared with 

 secretion, were left resting on some of the small sessile 

 glands. After 24 hrs. one of these cubes was found 



