Cua. 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 colonr 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. J 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 
