Ueber Blumen und Insecten 1 ). 



Brief F. Miillers an Ch. Darwin mit einleitender Bemerkung des letzteren. 



The enclosed letter from that excellent observer, Fritz Miiller, contains some 

 miscellaneous observations on certain plants and insects of South Brazil, which 

 are so new and curious that they will probably interest your naturalist readers. 

 With respect to his case of bees getting their abdomens dusted with pollen while 

 gnawing the glands on the calyx of one of the Malpighiaceae, and thus effecting 

 the cross-fertilisation of the flowers, I will remark that this case is closely analogous 

 to that of Coronilla recorded by Mr. Farrer in your journal some years ago, in 

 which parts of the flowers have been greatly modified, so that bees may act as 

 fertilisers while sucking the secretion on the outside of the calyx. The case is 

 interesting in another way. My son Francis has shown that the food-bodies of 

 the Bull's-horn Acacia, which are consumed by the ants that protect the tree from 

 its enemies (as described by Mr. Belt), consist of modified glands; and he suggests 

 that aboriginally the ants licked a secretion from the glands, but that at a sub- 

 sequent period the glands were rendered more nutritious and attractive by the 

 retention of the secretion and other changes, and that they were then devoured 

 by the ants. But my son could advance no case of glands being thus gnawed 

 or devoured by insects, and here we have an example. 



With respect to Solanum palinacanthum, which bears two kinds of flowers 

 on the same plant, one whith a long style and large stigma, the other with a 

 short style and small stigma, I think more evidence is requisite before this species 

 can be considered as truly heterostyled, for I find that the pollen-grains from the 

 two forms do not differ in diameter. Theoretically it would be a great anomaly 

 if flowers on the same plant were functionally heterostyled, for this structure is 

 evidently adapted to insure the cross-fertilisation of distinct plants. Is it not more 

 probable that the case is merely one of the same plant bearing male flowers 

 through partial abortion, together with the original hermaphrodite flowers? Fritz 

 Muller justly expresses surprise at Mr. Leggett's suspicion that the difference in 

 length of the pistil in the flowers of Ponlederia cor data of the United States is 

 due to difference of age; but since the publication of my book Mr. Leggett has 



i) Nature 1877. Bd. XVII. S. 78, 7y. 



