310 Miscellaneous. 
of development of the anthers. The cells of the inner membrane, 
which are at first confused with the tissues which form the outer 
membranes and other parts of the anther, begin to detach themselves 
from the contiguous tissues at the period when the pollinic utricles 
themselves acquire their peculiar appearance. The development of 
the cells of the third membrane, and that of the pollinic utricles, 
then proceed side by side until the pollen is nearly mature. But as 
this period approaches, and when the mother cells of the pollen 
have disappeared and the threads are produced in the fibrous cells, 
the third membrane shrivels, becomes lacerated, and is usually 
absorbed without leaving any traces, except a granular matter adhe- 
ring to the second membrane. 
As a provisional production intimately connected with the de- 
velopment of the pollen and the special organization of the fibrous 
cells, the third membrane seems to be of great biological importance. 
Its disappearance as the dehiscence of the anthers approaches, 
however, is subject to some exceptions. Thus it persists in various 
degrees in Hyoscyamus, Pedicularis, Convolvulus, Forsythia, Ery- 
thronium, Fuchsia, Paratropia, Crassula, Echeveria, Megazea, 
Aisculus, Citrus, Dictamnus, Helleborus, Linum, Reseda, Spar- 
mannia, Thea, Tropewolum, Arum, Dianella, Hemodorum, Loranthus. 
In anthers with apicilar dehiscence the third membrane is regu- 
larly persistent, as if in these anthers, which are found to be without 
fibrous cells, the non-destruction of the third membrane was con- 
nected with the non-production of fibrous cells in the second. 
Colour.—The third membrane is most frequently coloured, whilst 
the second is generally colourless. Its colour is also generally in- 
dependent of that of the epidermic membrane ; but the second mem- 
brane sometimes partakes of that of the third, as in Aponogeton, Gono- 
lobus, and Salvia splendens. 'The colour of the third membrane, on the 
contrary, is directly related to that of the pollen, so that the colour 
of the destroyed membrane may be known from that of the pollen ; 
and, on the other hand, the colour of the pollen may be foretold 
from that of the membrane. 
Structure.—The cells of the third membrane are sometimes papilli- 
form, sometimes flattened, but always possess very delicate walls. Some 
exceptions are presented in Pyrola, Cassia, Vaccinium, and Rhododen- 
dron, in which the anthers have no fibrous cells, and the internal 
membrane is strikingly thickened as if in compensation. The mem- 
brane is usually composed of a single layer of cells ; but there are two 
in Sparmannia, and from two to six in Viola, Crassula orbicularis, 
and some species of Cassia and Canna. The layers are most 
numerous towards the junction of the valves. The membrane does 
not only extend over the valves of the anther, but lines the whole 
cavity of the cells. 
Contents.—The chief contents of the cells of the third membrane 
are various colouring-matters, fatty bodies often united into drops 
charged with colouring-matters, nitrogenous substances, mucilage, 
sugar, and aleurone. 
Functions.—All its characters indicate that the third membrane 
