20 ON FLOWERS AND INSECTS. [LECT. 



in contact with any bee visiting the flower, and would 

 touch just that spot of the back on which pollen would 

 be deposited by a younger flower. In this manner 

 cross-fertilization is effectually secured. 



There are, however, several other curious points in 

 which ^S. officinalis differs greatly from the species last 

 described. 



The general form of the flower, indeed, is very similar. 

 We find again that, as generally in the Labiates, the 

 corolla has the lower lip adapted as an alighting board 

 for insects, while the arched upper lip .covers and protects 

 the stamens and pistils. 



The arrangement and structure of the stamens is, 

 however, very peculiar and interesting. As in Lamium, 

 they are four in number, but one pair is quite rudi- 

 mentary (Fig. 16). In the other (a a) the two anthers, 

 instead of being attached close together at the summit 

 of the filament, are separated by a long movable rod, or 

 connective (Figs. 19, 20, m), so that they can play freely 

 on the stalk of the stamen. In a natural position, this 

 connective is upright, so that the one anther is situated 

 (Fig. 16) in the neck of the tube, the other under the 

 arched hood. The lower anther, moreover, is more or 

 less rudimentary. Now when a bee comes to suck the 

 honey, it pushes the lower anther out of the way with 

 its head ; the result of which is that the connective swings 

 round, and the upper fertile anther comes down on to 

 the back of the bee (Figs. 17 and 20), and dusts it with 

 pollen, just at the place where, in an older flower (Fig. 

 18) it would be touched by the stigma, st. 



At first sight, it may seem an objection to this 

 view that some species as, for instance, the Common 



