391' M. S. B. Schnetzler on the Aenferous 



The cells of the outer layei* 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 gi'een 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- 

 ance. 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 force 

 thus produced is very considerable. Rcinsch (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 1'98-i milligr. About 597 utri- 

 cles may be counted upon oiie 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. ]\Iiclieli, in an interesting work on the colounng-inatter of cliloro- 

 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). 



