394 M.S. B. Schnetzler on the Aériferous 
The cells of the outer layer of the utricles contained chlorophyll- 
granules grouped towards the wall, whilst the interior was colour- 
less. The mushroom-like cells had their pileus already coloured 
brown. : 
This change of colour which takes place in the cells of the 
utricular walls, in which we see the green passing to rose, lilac, 
violet, and blue, evidently depends upon a chemical action in 
relation to the contents and function of the utricles. We must, 
in the first place, remark that the coloration of the interior cells 
is due to a liquid, whilst the granules of chlorophyll have dis- 
appeared or do not exist. These granules appear to have under- 
gone at the same time the action of a solvent and of a chemical 
agent which has changed their colour*. 
The red colour of the cell-liquids is generally ascribed to the 
presence of a free acid, and their blue colour to the existence of 
an alkali. In the utricles of Utricularia minor all the transitions 
between bright red and deep blue may be observed. 
At first the cavity of the utricles contains a mucilaginous 
liquid, of neutral reaction ; it is in this liquid that we afterwards 
witness the appearance of a little bubble of gas, which gradually 
increases in volume, whilst the liquid diminishes. The presence 
of this mucilaginous liquid may be very easily ascertained by 
changing the position of the utricle; the bubble of gas always 
tends to gain the most elevated part, by making its way through 
a viscous liquid which opposes to it a certain amount of resist- 
auce. In June and July the vesicles are almost all filled with 
air. The plant then rises to the surface of the water; and the ~ 
peduncle, which, in Utricularia minor, bears from two to five 
flowers of a pale-yellow colour, rises into the air, where the two 
unilocular anthers spread their pollen upon the stigma of the 
pistil, free from the contact of the water. The ascensional for¢e 
thus produced is very considerable. Reinsch (Mikroscop) as- 
sumes that, on the average, the capacity of one utricle (in U. 
vulgaris) is equal to 2°57 cubic millims., and the weight of a 
utricle to 0°6 milligramme ; the ascensional force of a single 
utricle would thus be equal to 1:964 milligr. About 597 utri- 
cles may be counted upon one main branch, the ascensional 
force of which amounts to 0°778 gramme ; and taking an entire 
plant, Reinsch obtains a total force of 4°44 grammes: counting 
four branches, we obtain 3:112 grammes. Now the weight of 
a tuft of flowers which rises above the level of the water is’ 
* M. Micheli, in an interesting work on the colouring-matter of chloro- 
phyll, shows that acids destroy the colour of chlorophyll and render it 
yellow; sulphuric and hydrochloric acids, in larger quantity, reconvert this 
yellow into blue or green; and baryta acts in an analogous manner 
(Archives des Sci. Nat, May 1867). ; 
