315 



OBSEEVATIONS ON PROTANDRY AND PROTOGYNY 

 IN BRITISH PLANTS. 



By Alfred W. Bennett, M.A., B.Sc, F.L.S. 



{Read at the Meeting of the British Association at Liverpool, 1870.) 



The arrangement of the reproductive organs in hermaphrodite plants, 

 the presence in the same flower of both pistil and stamens, suggested 

 to the minds of the older botanists no other idea than that of self- 

 fertilization. 



Sprengel was the first, at the close of tlie last century, to point out, 

 in his ' Das Entdeckte Geheimniss der Natur,' that it is frequently 

 impossible for the pistil to be fertilized by the pollen of stamens be- 

 longing to the same flower. His observations, however, attracted but 

 little attention from botanists generally, and were not followed out 

 until Darwin laid down his famous axiom that " nature tells us in the 

 most emphatic manner that she abhors perpetual self-fertilization." 



The most efl"ectual way, of course, of securing cross-fertilization, is 

 by unisexuality in the flowers ; and a very accurate observer of na- 

 ture, Mr. Robert Spruce, maintains, contrary to the general view, that 

 hermaphroditism is the earlier, unisexuality the later, stage in progres- 

 sive development. 



It is now generally admitted that, even in hermaphrodite flowers, 

 cross-fertilization is the rule, self-fertilization the exception. Two 

 sets of facts have been especially observed, — in particular by Darwin 

 in this country, Hildebrand in Germany, and Delphino in Italy, — to 

 favour cross-fertdization in hermaphrodite flowers ; the phenomena of 

 dimoi*phism and trimorphism, and the special arrangements which ren- 

 der it easier for the pollen to be brushed off by insects visiting the 

 flower than to fall on its own stigma. ' But, besides these, another 

 arrangement exists by wliich self-fertilization is hindered, the simple 

 fact that the stamens and pistil belonging to the same flower are fre- 

 quently not ripe, so to speak, at the same time. The only published 

 systematic observations on this point with which I am acquainted are 

 in Professor llildebrand's ' Die Geschlccliter-Vertheilung bei den 

 Pflanzen,' published in 1867 ; none have, as far as I am aware, been 

 systematically nuule in this country. The terms Protandnj and Fro- 

 toijyny used by Hildebrand to express, in tlie one case the development 



