510 



Anniversary Meeting » 



[Nov. 30, 



tility is only obtained by impregnating one form by the pollen of the 

 other, each species of Primula being divided into two sets or bodies, 

 which cannot be called distinct sexes, for both are hermaphrodite ; yet 

 they are so in a certain sense, for they require reciprocal union to effect 

 perfect fertility. This remarkable fact has as yet no known parallel. 

 The cross impregnation is effected by insects, the structure of insect and 

 flower being such that one form cannot by this means be im]3reguated 

 either by its own pollen or by that of a flower of its own form. 



In a subsequent paper Mr. Darwin has shown that in a species of the 

 genus Linum, which is also dimorphic, whilst the pollen in the two forms 

 is absolutely undistinguishable microscopically, and the stigmas differ 

 but slightly and not in any apparently important respect, tlie pollen of 

 one form is ineffectual when placed on the stigma of its own flower, but 

 acts immediately upon that of the other form. The generally received 

 idea that the impregnation of plants may be effected indifferently by 

 wind or by insects, is shoAvn to be fallacious ; plants being structurally 

 adapted for the one or the other, and not indifferently for either. 



He has similarly investigated a still more complicated case in the 

 common Lyihrum salicaria of our ditches, which, as regards its flowers, 

 is trimorphous, there being three instead of two sexual forms, differing 

 in the relative lengths of their two series of stamens and of their styles. 

 In estimating the novelty and value of Mr. Darwin's botanical dis- 

 coveries, we should not overlook that they have all been obtained by 

 the study of some of the most familiar and conspicuous of our native 

 plants, and some of the best-known and easily procured cultivated 

 exotics. 



Me. Busk, 



I will request you to present this Medal in the name of the Society 

 to your friend Mr. Darwin, and with it the expression of oui' deep regret 

 that the state of his health prevents the gratification which it would 

 have been to us all to have welcomed him here on this day. 



And you will be able to >tell him, from your own observation, the 

 hearty satisfaction with which the Society regards the bestowal of this, 

 its highest mark of esteem, in evidence of its appreciation of labours 

 almost incessantly pursued for now between thirty and forty years. 



The Council has awarded a Eoyal Medal to Warren De la Rue, 

 Esq., P.E.S., for his observations on the Total Eclipse of the Sun in 

 1860, and for his improvements in Astronomical Photography. 



The advantages which photography affords in the delineation of 

 celestial objects and phenomena are now generally recognized. This 

 art has been already successfully applied to depict the infinitely diver- 

 sified surface of the moon ; the sun with its spots and faculae, and those 

 mysterious appendages which are only to be seen during a total ecHpse j 



