320 BOTANY. [ch. xvi. 



Gray seems to have been written before the publication of 

 this paper, probably in 1856 or 1857 : 



"... What you say on Papilionaceous flowers is very 

 true ; and I have no facts to show that varieties are crossed ; 

 but yet (and the same remark is applicable in a beautiful 

 way to Fumaria and Dielytra, as I noticed many years ago), 

 I must believe that the flowers are constructed partly in 

 direct relation to the visits of insects ; and how insects can 

 avoid bringing pollen from other individuals I cannot un- 

 derstand. It is really pretty to watch the action of a 

 humble-bee on the scarlet kidney bean, and in this genus 

 (and in Lathy rus grandifiorus) * the honey is so placed 

 that the bee invariably alights on that one side of the 

 flower towards which the spiral pistil is protruded (bring- 

 ing out with it pollen), and by the depression of the wing- 

 petal is forced against the bee's side all dusted with pollen. 

 In the broom the pistil is rubbed on the centre of the back 

 of the bee. I suspect there is something to be made out 

 about the Leguminosas, which will bring the case within 

 our theory ; though I have failed to do so. Our theory 

 will explain why in the vegetable . . . kingdom the act 

 of fertilisation even in hermaphrodites usually takes place 

 sub jove, though thus exposed to great injury from damp 

 and rain." 



A letter to Dr. Asa Gray (September 5th, 1857) gives 

 the substance of the paper in the Gardeners' Chronicle : 



" Lately I was led to examine buds of kidney bean with 

 the pollen shed ; but I was led to believe that the pollen 

 could hardly get on the stigma by wind or otherwise, ex- 

 cept by bees visiting [the flower] and moving the wing 

 petals : hence I included a small bunch of flowers in two 

 Dottles in every way treated the same : the flowers in one I 

 daily just momentarily moved, as if by a bee ; these set three 

 fine pods, the other not one. Of course this little experi- 

 ment must be tried again, and this year in England it is too 

 late, as the flowers seem now seldom to set. If bees are 

 necessary to this flower's self-fertilisation, bees must almost 

 cross them, as their dusted right-side of head and right legs 

 constantly touch the stigma. 



"I have, also, lately been reobserving daily Lobelia fid- 



of "over-time" work. He wrote to a friend, "that confounded Leguminous 

 paper was done in the afternoon, and the consequence was I had to go to Moor 

 Park for a week." 



* The sweet pea and everlasting pea belong to the genus Lathyrus. 



