58 SURVEY or THE REPRODUCTIVE PROCESS 



gins, so as to leave them exposed, and allow impregnation 

 to be effected by the direct contact of the pollen grain with 

 the aperture of the coats at the apex of the nucleus, known 

 as the micropyle. 



The two coats and the nucleus of the ovule evidently 

 correspond to the double-wall and cellular contents of the 

 spore of the Rhizocarps, but it is in the development of a 

 peculiar intra-ovular structure — the Albuminous body — 

 that the principal interest of the comparison lies. It ori- 

 ginates as a simple cell, but as it enlarges it generates in 

 its interior a cellular mass, which may be held to repre- 

 sent the prothallium of the Cryptogamic spore. In its 

 substance are subsequently developed two or three minute 

 capsular bodies — the Corpuscula of Brown — each sur- 

 mounted by a crown of four cells, like those forming the 

 neck of the archegonium of the spore. The Corpuscula 

 contain minute cell-like bodies, the one at the base corres- 

 ponding to the germ cell of the archegonium, as well as to 

 the " germinal" or " embryonal" vesicles of other ovules. 

 Concomitant with this are the changes affecting the pollen 

 grains, which, though they present certain peculiarities in 

 Gymnospermeae, are formed, as in other Phanerogamia, 

 ^vithin a modified leaf or anther, by the quaternary division 

 of the contents of the central cells of the parenchyma. 

 From the exposed condition of the ovule in the Coniferge, 

 the grain finds direct axis to the micropyle, but it lies 

 there for some time before it protrudes the pollen tube. 



Schacht has observed that this outgrowth is connected 

 with a process of cell-development in the interior of the 

 grain, though he is not inclined on this account to allow 

 any analogy with the antheridial cellules of the Crypto- 

 gamia. In the pollen tube he admits only the presence of 

 free protoplasmic particles and starch grains.* Other 



* Vegetable Auat. Pliys. (Currey), p. 172-180. 



