DEPOSITION OF POLLEN. 277 



to describe the two processes of abstraction and deposition of pollen together. 

 Both have already been referred to, but a thorough description would have greatly 

 encroached on the account of the transference of the pollen by animals reserved 

 till now, and so it seems more natural to treat the deposition of pollen more 

 particularly here, while connecting it with the processes described above as occasion 

 requires. 



In the last chapter, when describing the change of position of anthers and 

 stigmas, it was especially noted that in the flower of the Grass of Parnassus 

 (Parnassia; see fig. 267* p. 249) one anther after another placed itself in the centre 

 of the flower, because the road to the honey ran through that part, and the sucking- 

 insects were therefore obliged to remove the pollen from the anther standing in 

 their way. But each anther in turn, as it stands in the centre, covers the stigma 

 which surmounts the egg-shaped ovary, and as long as this is the case, the pollen 

 from another flower cannot be deposited there. It is necessary that the last anther 

 of the series, after giving up its pollen, should move out of the way in order that 

 the stigma may be accessible. This actually occurs; the stigma alone is now to be 

 seen in the place where the five anthers have successively appeared, and when other 

 insects come to suck up the honey, the pollen they bring with them from other 

 flowers is deposited on the stigma. The same sort of thing happens in Funkia, 

 Centranthus and Impatiens. In the flowers of Impatiens, the anthers form a kind 

 of cap which covers the stigma so as to hide it completely when the flower first 

 opens. Only when the cap becomes loose and falls ofl" is the stigma exposed, 

 standing in the place formerly occupied by the anthers. In these cases the position 

 taken up by the stigma at the commencement of flowering is not usually altered, 

 so that it meets the pollen-laden insect in the exact place where the anthers formerly 

 stood. In order to attain this end, however, the styles of most Saxifrages (e.g. 

 Saxifraga bryoides, cuneifolia, Geum, rotundifolia, stellaris) as well as the 

 stigmas of many Gentians, and especially those in the revolver-flowers of the 

 Caryophyllacese undergo an alteration of position. Originally, the stigmas of these 

 flowers were placed together in the centre, and the pollen-bearing anthers stood in 

 a circle round them; but, after the anthers have fallen and their filaments have 

 shrivelled up, the style splits, that is to say, the stigmas separate from one another 

 and diverge, taking up the position formerly held by the anthers when liberating 

 their pollen. 



The styles of Labiatse undergo still more marked movements, as, for instance, 

 in the Sage (Salvia glutinosa), a representative of this order. When the flower first 

 opens only the end of the style projects as a simple point from the edge of the 

 upper lip (see figs. 271 ^ and 271 -, p. 262, the right-hand flowers). In this stage the 

 humble-bees, entering the flowers, only carry oflT pollen, and do not touch the top 

 of the style. Later, the style bends down like a bow, and its branches, at first 

 folded together into a single point, separate and place themselves in front of the 

 entrance to the flower, so that the approaching visitors — the humble-bees — must 

 leave on them the pollen they have brought from other and younger flowers (see 



