274 DROSOPHYLLUM LUSITANICUM.  ([Cuar. XV 
darkened by an immersion ¢f 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 carbonate of ammonia, and the glands now be- 
came 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 therefore 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 undecom- 
posed 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 contents were conspicuously 
aggregated. Several glands with bits of albumen and fibrin 
were darkened in between 2 hrs. and 3 brs. ; 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 
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 completely liquefied, but with 
a few white streaks still visible; the other was much 
rounded, but not quite dissolved. Two other cubes were left 
on tall glands for 2 hrs. 45 m., by which time all the 
