506 ON THE OEGANS AND MODE OF FECUNDATION 



ovula, are of a texture somewhat diiferent from that of the 

 greater part of the cavity, but still more obviously different 

 from that of the cavity of the style, being neither apparently 

 701] secreting nor consisting of similar utriculi. A narrow line 

 of like surface is found extending on each side of every 

 placenta nearly as far as it is ovuliferous. The three lines 

 occupying the upper part of the axes, and the six lines 

 marginal to the three placentae, may, for a reason which 

 will hereafter appear, be called the conducting surfaces of 

 the ovarium. 



The female organ, as now described, is in a proper state 

 to be acted upon by the pollen applied to the stigma, and 

 for the transmission of the fecundating matter into the 

 cavity of the ovarium, in a manner and form which I shall 

 presently attempt to explain. 



In reflecting on the whole evidence existing in favour of 

 the direct application of the pollen mass to the stigma, and 

 especially on the recent experiments of Professor Trevi- 

 ranus,^ I could no longer doubt that in this manner im- 

 pregnation was actually eflected in Orchidese ; and the sole 

 difficulty in my mind to its being the only way arose from 

 adverting to a circumstance that must have been remarked 

 by every one who has particularly attended to this family, 

 either in Europe or in tropical regions; namely, that all 

 the capsules of a dense spike are not unfrequently ripened : 

 a fact which at first seems hardly reconcilable with this 

 mode of fecundation, at least on the supposition that the 

 pollen mass is applied to the stigma by insects. 



Without going fully into the question at present, I shall 

 here only remark, that in several such cases I have satisfied 

 myself, by actual examination of the stigmata belonging 

 to capsules taken at many different heights in the spike, 

 that pollen, by whatever means, had actually been applied 

 to them.^ 



' Zeitschrift f. ThysioL ii, p. 225. 



' It may also be observed, that tlie same difficulty applies to many other 

 cases of dense inflorescence, as to the female spikes or strobili of Coniferse, 

 Zamia, and Zea ; in all of which the symmetry of the ripe fruit is generally 

 perfect, although partial failures of impregnatiou might be at least equally 

 expected. 



