320 Corda on the Impregnation of Plants. 



Us appearance, (Tab. 44, fig. 23,/) ; the future nucule is first per- 

 ceived by a metamorphosis of matter and form taking place at the 

 base of the almost homogeneous cavity. In this state it is nearly 

 impossible with our instruments to ascertain its internal structure ; for 

 it appears like a scarcely congealed fluid. At a later period we per- 

 ceive the nucule (/) occupying the base of the secundine, (Tab. 

 44. fig. 24,) in a state of greater development, and already exhibit- 

 ing cellular texture. A membranous layer of the parenchyma of 

 the secundine begins to separate at this time, appearing as a nearly 

 transparent narrow border. About this time the endostome (e') be- 

 gins to be perceptible. 



In the third and fourth state of the ovules, the secundine and nu- 

 cule increase simultaneously ; but a conical wart (Tab. 44, fig. 25 — 

 28) occupies the endostome and projects from the cavity ; this ap- 

 pearance might easily lead to the erroneous supposition, that there 

 was in this case an union of two membranes. The cellular mem- 

 brane and the substance of the nucule (Tab. 44, fig. 25 — ^28) have 

 now attained considerable firmness and the cells have become opaque. 



In the fifth state we perceive a well defined orifice to the nucule, 

 and the cellular substance of the secundine being filled with starch, 

 the ovule itself appears firmer. The sac of the nucule is composed 

 of large six-sided cells, (Tab. 43, fig. 1 9,) originally filled with a 

 turbid fluid, which congeals into a somewhat crystalline matter, 

 (Tab. 43, fig. 20, s.) In the cell (r) this crystalline matter appears in 

 the form of somewhat wax-like, firm, and yellowish polyhedral bodies, 

 (s.) The cells which contain this congealed matter are connected 

 with each other, so as to form on the outer surface of the nucule a 

 beautiful net work, (Tab. 42, fig. 7, Tab. 43, fig. 14, 15, 19, 20, and 

 Tab. 44, fig. 23—29.) 



The nucule itself is about half the size of the secundine, and is 

 situated at the base of the latter ; and while the perforation of the 

 endostome is incomplete, the opening of the nucule, which we call 

 the embryostome, is merely indicated. In the further growth of the 

 ovule previous to impregnation, we perceive the embryostome to en- 

 large considerably and to connect itself with the endostome through 

 the cavity of the secundine. 



This brief account appears to me sufficient to enable us to follow 

 the course of impregnation through the secundine into the interior 

 of the ovule. 



