186 
ORGANOGRAPHY. 
BOOK I. 
cases are, and in the two others are not, absorbed. “ This 
same condition may be seen as a temporary stage in the de- 
velopement of Picea and Abies, in the months of January 
and February, in Finns in February and March, in which a 
loose waxy pollen mass may be found embedded in each divi- 
sion of the anther. At a somewhat later period we may see 
the four cells in Picea and Abies, in which the four pollen- 
grains lie closely united ; and it offers a pleasing spectacle 
under the microscope to observe each grain expand itself by 
the absorption of water until it bursts its case in order to 
escape, leaving the four cells emptied of their contents.” 
Link supposes the cellular substance in which pollen is 
generated to be semiorganic, and calls it collenchyma, con- 
sidering with me that it is what forms the appendage of the 
pollen masses of Orchidacese. But it can hardly be called 
semiorganic, especially if it is examined in Polystachya ra- 
mulosa. 
It also appears from Mr. Francis BauePs observations, 
that the masses of pollen of both Asciepiadaceae and Orchi- 
daceae, in the most solid state, are truly cellular, the grains 
of pollen being contained in cavities, the walls of which are 
either separable from each other, as in some Orchidaceae, or 
are ruptured without a separation of the cavities, as in 
Asciepiadaceae. (See the Observations on Orchidacece and 
Asclepiadacece, before referred to.) It does not however 
follow that because pollen is engendered in the interior of 
cells, its grains must therefore adhere originally by an um- 
bilicus ; and in fact the part so described by Turpin has no 
existence. 
When they are fully formed the granules are generally dis- 
charged at once, upon the dehiscence of the anther. But in 
some Araceae, which emit their pollen by a hole in the apex 
of their anther, the formation or developement of pollen must 
be going on for a considerable time after the first emission. 
A single anther continues to secrete and discharge pollen, 
till, as Brown remarks, the whole quantity produced greatly 
exceeds the size of the secreting organ. 
The surface of the pollen is commonly smooth. In some 
plants it is hispid, as in the Gourd and Ipomcea purpurea ; 
