540 ON THE ORGANS AND MODE OF FECUNDATION 



its descent being gradual until the cords nearly equal the 

 length of the placenta, to which they are parallel and 

 approximated. 



That these cords are not in any degree derived from 

 those portions of the walls of the cavity of the ovarium, to 

 which they are closely applied, and which I have termed 

 the conducting surfaces, is manifest from the identity in 

 state of those surfaces before and after the production of 

 the cords. 



In Bonatea the first evidence of the action of the poUen 

 consists in the withering of the stigma ; a similar decay of 

 the greater part of the style soon follows, and the enlarge- 

 ment of the ovarium generally begins before the withering 

 of the style is completed. When the enlargement of the 

 ovarium is considerable, and the mucous cords are fully'' 

 formed in its cavity, a corresponding enlargement of the 

 ovula takes place, and the nucleus becomes first visible. 



I have no satisfactory observations in Bonatea respecting 

 any tubes going off' from these cords and mixing with the 

 ovula ; but in Orcliis Morio I have repeatedly and very 

 clearly observed them scattered in every part of the surface 

 of the placenta, and in not a few cases have been able to 

 743] trace them into the aperture of the ovulum, to which 

 they adhere with considerable firmness.^ 



At what period they reach the foramen of the testa, 

 whether before or immediately after the first faint appear- 

 ance of the nucleus, I have not yet been able to determine. 

 That the tubes thus traced to the foramen of the ovulum 

 are of the same nature as those which I have called mucous 

 tubes, and not those directly produced by the pollen, is 

 proved by their exact agreement with the former in every 

 respect, except in their being remarkably and irregularly 

 fiexuose, apparently from the numerous obstacles they have 

 to overcome after leaving the cords and beginning to mix 

 with the ovula ; for^ in the cords themselves, where the 



^ [" Carefully" in the original — an obvious error of the press. — Edit.] 

 ^ Since these additional observations were read, 1 have found in several 

 other Orchidese, especially //afejzan'a viridis and Ophri/s apifera, tubes scattered 

 over the surface of the placenta, and not unfrequentlj inserted, in like manner, 

 into the apertures of ovula. 



