480 Mr. VALENTINE on the Development of the Theca, 
good reason for supposing that the vivifying matter communicated by the 
pollen tubes to the placenta is by some unknown means transmitted by the 
latter to the foramen of the ovulum, through which it finally passes into the 
nucleus, there to become the new embryo*.” It is a well established fact that 
the embryo, or essential part of the seed, is derived from the pollen, and that 
the membranes which are produced by the pistillum only act as a protection 
and channel of nutrition to the embryo, until such time as it shall be enabled 
to provide for itself. Mr. Drummond, in a paper published in the 13th volume 
of the Linnean Transactions, proved, beyond a doubt, that the sporules of 
Mosses germinate by emitting * pellucid filaments" from any points in their 
surface. J have myself examined the germinating sporules of Funaria hygro- 
metrica; and I found that the brown coat burst sometimes in two or three 
places, but most frequently in one only ; and there protruded from each fissure 
a delicate transparent tube containing the moving particles, which had pre- 
viously occupied the cavity of the sporule. These tubes, or, to speak with 
more precision, elongated cells, gradually increased in length, and, from 
exposure to light, became of a green colour. They soon became jointed, from 
the addition of fresh cells at the extremities. They then began to branch, and 
after a time produced leaves. 
The only difference that I can find between pollen and liporules:i is, that 
the coat of the latter is of a more rigid and opake texture. From this 
difference it is that the sporules rarely burst in a sudden manner upon 
the applieation of water; but when they do, the moving particles are dis- 
charged loose in the water, precisely in the same manner as are those of the 
pollen. In both sporules and pollen it is necessary, to the production of the 
tubes, that the laceration of the coats should take place slowly. 
Without reference to the evidence here adduced, we do not overstep the 
bounds of probability in supposing that in plants of a complicated organiza- 
tion there exists a necessity that the embryo should be protected by a nidus 
capable of imparting aliment until it shall become sufficiently organized to be 
capable of reproducing a plant equal in complexity of structure to its parent. 
Whilst in the Ce//ulares the process of their growth is so little complicated 
* Mr. Brown has actually traced the pollen tubes into the foramen of the ovulum in Orchis M. orio, 
Habenaria viridis and Ophrys apifera. See Linnean Transactions, vol. xvi. p. 742. 
