IN SUMATRA. 229 



they have a singular knee extended into a fork-like projection,/, 



which in the flower lies just below the bright yellow anthers 



of the short stamens. The lower portion of the long stamens 



takes a backward curve from the 



fork carrying the pores of its 



anthers far from those of the 



short stamens. This arrange- "^i^t^^/ 



ment is most beautifully adapted, 



as was first pointed out by Fritz ' ' 



Muller, for the cross-fertilisation flower (DiAORAMjiATrc) of melastoma. 



nf tViP nlaTit ^^ section.— j), PETAL; a\ AXTJiElt 



L>1 mc JJlttUU. ^ OF SHOKT STAMENS ;/, FORK OF 1 OXG 



The bees invariably made stamkns ; a^ anther of long sta- 



J il 1, • l,i II 1 i^ JiENS ; C. FILAMENT OP LONG ANTHEK ; 



tor the bright yellow platform »(, stigma of pi»til ; 8, ovary. 

 offered by the bunch of short 



stamens (perhaps because they do not perceive from a distance 

 the pink pistil and long stamens projected against the 

 pink corolla), and invariably received the pistil between their 

 legs, their feet settling also on the adjoining fork of the long 

 stamens. The instant effect of this is to collect the whole 

 of the long stamens into a bunch, and to depress their anthers 

 downwards and away from the body of the bee, while the 

 stigma of the pistil (which hangs down close to the pores 

 of the long-stamened anthers) remains in constant contact 

 with its ventral side. At the moment of the bee's depar- 

 ture, the hooks on its feet, by pulling on the fork of the long 

 stamens, raise their anthers, bringing — now that there is no 

 fear of producing self-fertilisation of the plant — their tips in 

 a collected bunch into contact with its sides and abdomen. 

 Long after I had made these observations, while working in the 

 laboratory of the Buitenzorg Gardens, Dr. Burck pointed out to 

 me a fact of considerable importance which I was able to verify 

 for myself, that there was in very closely allied species of this 

 family a great difference in the shape of the pollen of the two 

 forms of anther ; that while pollen of both shapes was found on 

 the pistil, that from the long stamens alone seemed fertile. We 

 could not detect any pollen tubes (which are emitted when the 

 pollen is fecundating the plant) emanating from the pollen of 

 the short-stamened anthers. 



The reason why some organ of a plant or animal has assumed, 

 as it were, an abnormal form, is not always easy to discover ; 



