Cor da on the Impregnation of Plants, 319 



those of the great Englishman,* nor from the investigations of Mir- 

 bel ; but as we have to follow the course of the pollen-tubes into the 

 innermost cavity of the ovules, it is necessary to be acquainted with 

 their structure. 



Robert Brown was, we know, the first to demonstrate the pistillate 

 flower in Coniferse and Cycadeee to be a naked ovule. This naked 

 ovule is situated in a bottle-shaped cavity of the inside of the scale, 

 which is directed downwardly and inwardly (Tab. 42, fig. 3, h) and 

 its first or outer coat (primine) (Tab. 42, fig. 3, c ; Tab. 43, fig. 14 ; 

 and Tab. 44, fig. 22, ccc) is coherent with the inner surface of the 

 cavity ; therefore both together form the exostome, (Tab. 42, fig. 3, 

 and 44, fig. 21, e' e^.) But this intimate union only exists in the 

 early state ; they are gradually loosened by the ripening of the seeds, 

 and at length the primine is completely separated from the walls of 

 the cavity. While the inner side of the wall of the scale is being 

 separated, a portion of the integuments of the scale tears loose, and 

 appears like a wing half surrounding the base of the ripened seed, 

 (Tab. 44, fig. 30, x. and 33.) 



During the ripening of the ovules, the exostome closes more and 

 more, the primine gradually thickens, and becomes harder and almost 

 corneous, and finally appears as a hard covering to the seed, (fiesta 

 vel membrana externa seminis.y 



In an earlier stage, while the primine of the ovule is yet coherent 

 with the surface of the cavity in the scale, we find in the upper part 

 a free empty space, (Tab. 42, fig. 3, Tab. 43, fig. 14, and Tab. 44, 

 fig. 21 and 22, c' c' c' c') into which the summit of the (zapfenarti- 

 gen) secundine (Tab. 42, fig. 3, 4, 5, Tab. 42, fig. 14, and Tab. 

 44, fig. 21 — 29) projects. This free space (which in the scale is 

 under the ovule, the latter being suspended) is limited by the con- 

 nexion of the secundine to the nucule and primine, (Tab. 43, fig. 



14, g-) 



The secundine (Tab. 43, fig. 14, dd) is a rather firm, hollow 

 body, (zapfen,) which is connected with the nucule at the base, and 

 terminated by its orifice at the other extremity. The nucule (//) 

 of the ovules of Pinus is situated within the secundine, \v\X\\ which 

 it is coherent only at the base. An exception which 1 have not 

 previously observed in any other ovule. The secundine is originally 

 a short conical body, in which a small, roundish, obscure spot makes 



* Robert Brown, Botanicorum facilh princeps. — Trans. 



