704 Mr. Brown on the Organs and Mode of 



similar utriculi. A narrow line of like surface is found extend- 

 ing on each side of every placenta nearly as far as it is ovuli- 

 ferous. 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 espe- 

 cially on the recent experiments of Professor Treviranus*, I 

 could no longer doubt that in this manner impregnation was 

 actually effected in Orchideae ; and the sole difficulty in my 

 mind to its being the only way arose from adverting to a cir- 

 cumstance that must have been remarked by every one who has 

 particularly attended to this family, either in Europe or in tro- 

 pical regions ; namely, that all the capsules of a dense spike are 

 not unfrequently ripened : a fact which at first seems hardly 

 reconcileable with this mode of fecundation, at least on the sup- 

 position 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. Physiol, ii. p. 225. 



f tt may also be observed, that the same difficulty apphes to many other cases of 

 dense inflorescence, as to the female spikes or strobili of Coniferas, Zamia, and Zea ; 

 in all of which the symmetry of the ripe fruit is generally perfect, although partial 

 failures of impregnation might be at least equally expected. 



Believing, 



