310 PINGUICULA VULGARIS. [Cuar. XVI. 
then began to dry. Nor could their complete dissolution have been 
expected from what we have seen with Drosera. 
(11) Minute drops of skimmed milk were placed on a leaf, and these 
caused the glands to secrete freely. After 3 hrs. the milk was found 
curdled, and after 23 hrs. the curds were dissolved. On placing the 
now clear drops under the microscope, nothing could be detected except 
some oil-globules. ‘he secretion, therefore, dissolves fresh casein. 
(12) Two fragments of a leaf were immersed for 17 hrs., each in a 
drachm of a solution of carbonate of ammonia, of two strengths, 
namely of one part to 437 and 218 of water. The glands of the 
longer and shorter hairs were then examined, and their contents found 
aggregated into granular matter of a brownish-green colour. These 
granular masses were seen by my son slowly to change their forms, 
and no doubt consisted of protoplasm. The aggregation was more 
strongly pronounced, and the movements of the protoplasm more rapid, 
within the glands subjected to the stronger solution than in the others. 
The experiment was repeated with the same result; and on this 
occasion I observed that the protoplasm had shrunk a little from the 
walls of the single elongated cells forming the pedicels. In order to 
observe the process of aggregation, a narrow strip of leaf was laid 
edgeways under the microscope, and the glands were seen to be quite 
transparent; a little of the stronger solution (viz. one part to 218 of 
mater) was now added under the covering glass; after an hour or two 
the glands contained very fine granular matter, which slowly became 
coarsely granular and slightly opaque; but even after 5 hrs. not as yet 
of a brownish tint. By this time a few rather large, transparent, 
globular masses appeared within the upper ends of the pedicels, and the 
protoplasm lining their walls had shrunk a little. It is thus evident 
that the glands of Pinguicula absorb carbonate of ammonia; but they 
do not absorb it, or are not acted on by it, nearly so quickly as 
those of Drosera. 
(18) Little masses of the orange-coloured pollen of the common pea, 
placed on several leaves, excited the glands to secrete freely. Even a 
very few grains which accidentally fell on a single gland caused the 
drop surrounding it to increase so much in size, in 23 hrs., as to 
be manifestly larger than the drops on the adjoining glands. Grains 
subjected to the secretion for 48 hrs. did not emit their tubes; they 
were quite discoloured, and seemed to contain less matter than before; 
that which was left being of a dirty colour, including globules of oil. 
‘They thus differed in appearance from other grains kept in water for 
the same length of time. The glands in contact with the pollen-grains 
had evidently absorbed matter from them; for they had lost their 
natural pale-green tint, and contained aggregated globular masses of 
protoplasm. 
(14) Square bits of the leaves of spinach, cabbage, and a saxifrage, 
and the entire leaves of Erica tetralix, all excited the glands to 
increased secretion. The spinach was the most effective, for it caused 
the secretion evidently to increase in 1 hr. 40 m., and ultimately to run 
