322 Corda on the Impregnation of Plants. 
impregnation, even until the embryo has assumed an egg-shaped 
form, and has increased very considerably in size, becoming at the 
same time firmer and nearly opaque, (Tab. 44, fig. 22, a’ and E.) 
At this period the embryostome contracts, (Tab. 44, fig. 22, f”) the 
nucule becomes thinner, and being, as well as the secundine (d,) 
confined between the growing embryo within, and the primine. (cc) 
without, both these membranes become very much compressed. 
The pollen-tubes (Tab. 44, fig. 22 a’) are at this time very much 
attenuated and filiform, and so much shrivelled that neither cavity 
nor contents can be observed ; they are, moveover, so much attenu- 
ated at the extremity next the embryo-sac that it becomes very dif- 
ficult to trace them to that body, and demonstrate their connexion 
with its surface, which is now rough and nearly opaque. 
About this time the pollen-tubes appear to fall away, and, on ac- 
count of the solidifying of the albumen, it becomes impossible to 
perceive any vestige of its former presence. 
After having considered the fecundation and the structure of the 
ovule, I undertook to examine the different integuments of the ma- 
‘ture seed. The ripe seed of the Rothtanue (Pinus Abies) is fur- 
nished with a wing, (Tab. 44, fig. 30, », and fig. 33,) the base of 
which (6) half surrounds the nut; the upper part, like a fine, thin, 
separated portion of integuments, forms the wing itself, (¢.) This 
wing is nothing else than the inner skin of the lower part of the 
inner surface of the scale; and the line of separation is visible at an 
early period, (Tab. 44, fig. 21, t,) by which, when the seeds are 
ripe the cavity of the ovule opens and the formation of the wing 1s 
effected. By removing this wing, the nut is seen free from all con- 
nexion, (Tab. 44, fig. 30 w and 31.) The vestige of an opening is 
observable at its summit ; (the endostome of the ovule (Tab. 44, fig. 
31, 32 and 34 e’e’,) called the micropyle by Turpin,) perforating 
the hard covering of the seed (testa) which represents the primine 
of the ovule, (Tab. 42, fig. 3; Tab. 44, fig. 21, 22, and 34, cee-) 
Beneath the testa and partly coherent with it, is the inner covering 
of the seed, (Tab. 44, fig. 34, d,) a brownish skin which represents 
the secundipe of the ovule, (Tab. 42, fig. 3, and Tab. 44, fig. 21, 22, 
and 34, d,d,d.) Its opening, the endostome (Tab. 44, fig. 34, 
e?-+f’) is firmly connected with the embryostome, (Tab. 44, fig. 
22 f’) of the kernel-skin, (nucule,) (Tab. 44, fig. 21 f, 22, and 
34 f.) In the fecundated ovule and ripe seed there is situated, im 
and near the orifice of these three imteguments, a yellowish, firm 
and shrivelled body, of a loose texture, which was called by Gzrt- 
