VOL. LV.] PHILOSOPHICAL TRANSACTIONS. 251 



substances, that could pass freely with the current of the juices in which they 

 floated ; but their regular progress towards the germen was doubtless interrupted 

 by the gathering of the flower; so that the motion observed could only be 

 ascribed to accidental attractions, which put the juices in motion between the 

 talks; and this was evident also from the direction of their motion, which was 

 casual, and not always leading towards the germen. The number of the prin- 

 cipal ducts that lead to the germen cannot be ascertained; they probably vary 

 according to the number of loculaments to be supplied; more than one was 

 commonly observable with the corpuscles passing in close files through them, as 

 has already been described. In the pistilla of flowers in bud, no corpuscles 

 could be discovered; which is a strong proof that they are received from the 

 pollen, and destined for the impregnation. 



On examining the pappus or down that crowns the seeds in the class synge- 

 nesia, the hairs of the pappus were found to be hollow, and filled with the same 

 corpuscles (fig. "24). How the corpuscles are admitted into them, or for what 

 purpose they are lodged there, must be left to further inquiry ; in the mean time 

 it may be observed, that the situation of the pappus makes it improbable that the 

 corpuscles should be received for the purpose of conveying them to the germen ; 

 and that therefore it is more natural to suppose, that the corpuscles arrive there 

 after their passage through the germen, and that the hairs of the pappus serve as 

 excretory vessels for taking off those that were useless to the impregnation. This 

 is the more probable, as the great quantity of tliem brought by the ducts must 

 doubtless occasion such a superfluity. 



On examining various plants of the order Alices, of the class cryptogamia, no 

 male organs could be discovered. If the flowers of these plants be hermaphro- 

 ditic, the staminiferous part doubtless falls off as soon as the impregnation is over, 

 as it does in other cases; so that if the male organs are not sought for at the 

 precise time when the plant is in bloom, the search must be a vain one. The 

 fructification in these plants is for the most part covered with a thin membrane, 

 which Mr. Miles calls a sort of fungus or tubercle (Phil. Trans., Abridg. vol. viii, 

 p. 505) and which, at its first appearance, and for some time afterwards, seems 

 to have its margin closely adhering to the leaf. If the antherae lie under this 

 cover, it is probable that the flowers do not blow till the margin has detached it- 

 self from the leaf, and admits the air to come under it, for the maturation and 

 dispersion of the pollen. This may perhaps point out the critical time for search- 

 ing for the antherae. However this may be, the antherae and pollen are probably 

 very minute; and as it is no easy task to make the examination of what is con- 

 cealed under these membranes with a single microscope, to which the glasess we 

 have used are commonly applied, we have not yet found the means of disco- 

 vering them. The seed vessels and seeds have been already well described and 



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