5o8 



NATURE 



\Oct. II, 1877 



2. Whilst the flowers of Labiatae are generally adapted 

 to be fertilised only by bees of a certain size, smaller 

 ones entering the flowers without touching either the 

 stigma or the anthers ; in the genus Salvia, on the contrary, 

 larger and smaller bees have been equally engaged in 

 the service of intercrossing. This has been effected by 

 the foMowing modifications : — The stigma bends further 

 downwards, and the connective of each of the two lower 



stamens has been transformed to an upright, two-armed 

 lever, which, at its two opposite ends, bears the two 

 anther-cells, and, by a slight pressure on either of them, 

 turns on the filament, so that any bee entering the flower 

 cannot but strike against the two lower anther-cells with 

 its head, cause the connective to rotate, and thus bring 

 the dehiscent surfaces of the upper anther-cells into close 

 contact with its back. In direct connection with this 



transformation of the two lower stamens, the two upper 

 ones, which would hinder the rotation of the levers, have 

 aborted. But in contrast with the uppermost stamen, 

 which has become superfluous at a much earlier period 

 in the ancestors of the whole family Labiata;, and has 

 since completely disappeared, the two upper lateral 

 stamens, which have become useless not earlier than in 

 the ancestors of the genus Salvia, in all or most of the 

 species of Salvia still exist in the form of two little knobs 

 (x. Figs. 120-130). 



3. By thetransformation just-mentioned of the two lower 

 stamens in the genus Salvia not only have the two upper 

 stamens become a hindrance, and thus been aborted, but 

 at the same time the lower anther- cells of the two lower 

 stamens have been alienated from their original function 



Fig 123. 



Fi<fl2i. 



and engaged in a new service, by which a sterilisation and 

 metamorphosis of these has also been occasioned. Salvia 

 officinalis and prateiisis show us two steps of this further 

 modification. In .S'. officinalis^ the connective (r/. Fig. 

 130) is but moderately lengthened, the two lower anther- 

 cells, although reduced in size, still commonly produce 



' The peculiarities of Salvia officittalis have been fully and excellently 

 described and explained by JDr. \Villiam Ogle. {Popular Science Revieiv, 

 July 1&69, p. 261-267.) 



some pollen, but sometimes they are quite sterile ; they 

 are not yet grown together, but only adherent to each 

 other so as generally to move in company. In Salvia 

 pratensis, on the contrary, the two lower anther-cells are 

 not only always completely sterile, but also metamor- 

 phosed into two concave plates (/, Fig. 11 8- 120) firmly 

 grown together in front (at the point p. Fig. 11 8- 120), so 

 that they act as a simple plate, which, when pressed by 

 the head of a humble-bee, causes the two connectives 

 to rotate, and brings the pollen of the two upper anther- 

 cells into contact with the back of the visitor. 



4. In the small female flowers of Salvia pratensis, 

 also, whatever may have been their origin," the last two 



FifjJSS 



JTOj, 



igjsa 



F iff 12 



anther-cells have become sterile, increased fertility of the 

 small-flowered plants probably also in this species, as in 

 other gynodicecious Labiatx," compensating for the de- 



I I have attempted to give an explanation of the origin of the small- 

 flowered female form of the gynodicecious Labia'a; in Nature, vol. viii , 

 P- 161. This explanation, however, is not in accordance with Mr. Darwin's 

 views published in his newest work, *'On the Different Forms of Flowers.'' 



^ As shown by Mr. Darwin, *'On the Different Forms of Flowers," 

 pp. 299-309J 



