314 PINGUICULA VULGARIS. (Caar. XVI. 
From the foregoing experiments and observations we see 
that objects not containing soluble matter have little or no 
power of exciting the glands to secrete. Non-nitrogenous 
fluids, if dense, cause the glands to pour forth a large supply 
of viscid fluid, but this is not in the least acid. On the 
other hand, the secretion from glands excited by contact 
with nitrogenous solids or liquids is invariably acid, and is 
so copious that it often runs down the leaves and collects 
within the naturally incurved margins. The secretion in 
this state has the power of quickly dissolving, that is of 
digesting, the muscles of insects, meat, cartilage, albumen, 
fibrin, gelatine, and casein as it exists in the curds of milk.* 
The glands are strongly excited by chemically prepared 
casein and gluten; but these substances (the latter not 
having been soaked in weak hydrochloric acid) are only 
partially dissolved, as was likewise the case with Drosera. 
‘The secretion, when containing animal matter in solution, 
whether derived from solids or from liquids, such as an 
infusion of raw meat, milk, or a weak solution of carbonate 
of ammonia, is quickly absorbed; and the glands, which 
were before limpid and of a greenish colour, become brownish 
and contain masses of aggregated granular matter. This 
matter, from its spontaneous movements, no doubt consists of 
protoplasm. No such effect is produced by the action of non- 
nitrogenous fluids.. After the glands have been excited to 
secrete freely, they cease for a time to secrete, but begin 
again in the course of a few days. ve 
Glands in contact with pollen, the leaves of other plants, 
and various kinds of seeds, pour forth much acid secretion, 
and afterwards absorb matter probably of an albuminous 
nature from them. Nor can the benefit thus derived be 
insignificant, for a considerable amount of pollen must be 
blown from the many wind-fertilised carices, grasses, &c., 
growing where Pinguicula lives, on to the leaves thickly 
covered with viscid glands and forming large rosettes. Even 
same use in the Italian Alps. The 
property of the plant seems to be 
widely known among primitive 
* (Pf.ffer (‘ Ueber fleischfessende 
Pflanzen,’ in the ‘Landwirthschaft. 
Jahrbiicher,’ 1877) quotes Linneus 
(‘Flora Lapponica,’ 1737, p. 10) to the 
effect that certain Lapland tribes use 
the leaves of Pinguicula to coagulate 
milk. Pfeffer learnt from an old 
shepherd that they are put to the 
people, for, within the last 30 years, 
it was used as rennet by mountain 
farmers in North Wales. I have 
myself succeeded in curdling milk 
with this vegetable rennet.—F. D.] 
