Ciar. XV.] SECRETION. 271 
and had never caught an insect, yet the secretion on all the 
glands coloured litmus paper of a bright red. From the 
quickness with which the glands are able to obtain animal 
matter from such substances as well-washed fibrin and 
cartilage, I suspect that a small quantity of the proper 
ferment must be present in the secretion before the glands 
are excited, so that a little animal matter is quickly 
dissolved. 
Owing to the nature of the secretion or to the shape of 
the glands, the drops are removed from them with singular 
facility. It is even somewhat difficult, by the aid of a finely 
pointed polished needle, slightly damped with water, to place 
a minute particle of any kind on one of the drops; for on 
withdrawing the needle, the drop is ‘generally withdrawn; 
whereas with Drosera there is no such difficulty, though the 
drops are occasionally withdrawn. From this peculiarity, 
when a small insect alights on a leaf of Drosophyllum, the 
drops adhere to its wings, feet, or body, and are drawn from 
the gland ; the insect then crawls onward and other drops 
adhere to it; so that at last, bathed by the viscid secretion, 
it sinks down and dies, resting on the small sessile glands 
with which the surface of the leaf is thickly covered. In 
the case of Drosera, an insect sticking to one or more of the 
exterior glands is carried by their movement to the centre of 
the leaf; with Drosophyllum, this is effected by the crawling 
of the insect, as from its wings being clogged by the secretion 
it cannot fly away. 
There is another difference in function between the glands 
of ‘these two plants: we know that the glands of Drosera 
secrete more copiously when properly excited. But when 
minute particles of carbonate of ammonia, drops of a solution 
of this salt or of the nitrate of ammonia, saliva, small insects, 
bits of raw or roast meat, albumen, fibrin or cartilage, as well 
as inorganic particles, were placed on the glands of Droso- 
phyllum, the amount of secretion never appeared to be in 
the least increased. As insects do not commonly adhere to 
the taller glands, but withdraw the secretion, we can see 
that there would be little use in their having acquired the 
habit of secreting copiously when stimulated; whereas with 
Drosera this is of use, and the habit has been acquired. 
Nevertheless, the glands of Drosophyllum, without being 
stimulated, continually secrete, so as to replace the loss by 
evaporation. Thus when a plant was placed under a small 
