Chap. III. PAEAMBA. 131 



of Linum perenne each separate stigma rotates on its 

 own axis, when the flower is mature, so as to turn its 

 papillose surface outwards. There can be no doubt 

 that this movement, which is confined to the long- 

 styled form, is effected in order that the proper sur- 

 face of the stigma should receive pollen brought by 

 insects from the other form. Now with Faramea, as 

 Fritz Miiller shows, it is the stamens which rotate on 

 their axes in one of the two forms, namely, the short- 

 styled, in order that their pollen should be brushed off 

 by insects and transported to the stigmas of the other 

 form. In the long-styled flowers the anthers of the 

 short enclosed stamens do not rotate on their axes, 

 but dehisce on their inner sides, as is the common 

 rule with the Eubiaeeae; and this is the best position 

 for the adherence of the pollen-grains to the proboscis 

 of an entering insect. Fritz Miiller therefore infers 

 that as the plant became heterostyled, and as the 

 stamens of the short-styled form increased in length, 

 they gradually acquired the highly beneficial power of 

 rotating on their own axes. But he has further shown, 

 by the careful examination of many flowers, that this 

 power has not as yet been perfected; and, consequently, 

 that a certain proportion of the pollen is rendered use- 

 less, namely, that from the anthers which do not rotate 

 properly. It thus appears that the development of the 

 plant has not as yet been completed; the stamens have 

 indeed acquired their proper length, but not their full 

 and perfect power of rotation.* 



* Fritz Miiller gives another in- with the nocturnal habits of these 



.stance of the want of absolute per- insects, most of the flowers open 



fection in the flowers of another only during the night; but some 



member of the Bubiacese, namely, open in the day, and the pollen 



Pumqueria fraprana, which is of such flowers is robbed, as Fritz 



adapted in a most wonderful man- Miiller has often seen, by hnmble- 



ner for cross-fertilisation by the bees and other insects, without 



aptcney of moths. (See ' Bot. Zeit- any benefit being thus conferred 



ung,' 1866, No, 17.) In accordance on the plant. 



