LEGUMINOSAE 331 



Towards the end of the bud period, the anthers dehisce, filling the conical 

 space at the end of the carina with pollen; at the same time the filaments are 

 retracted. The stigma and stylar brush get covered with pollen, some of which 

 is squeezed out at the tip of the carina when this is depressed. When the parts 

 of the flower resume their original position the edges of the stylar aperture scrape 

 off the pollen, which then of course remains outside the carina. The ends of the 

 filaments lying in the lower part of the conical anther-chamber are somewhat 

 thickened and club-shaped after the anthers have dehisced. When the carina is 

 depressed they push the pollen before them, so that the supply on the stylar brush 

 is constantly renewed. 



The interlocking and union of the parts of the flower are advantageous, because 

 nectar-seeking insects are compelled to apply the necessary force in order to 

 operate the mechanism by which the stigma is rubbed against the pollen-covered ventral 

 surface of a visitor, and this is dusted afresh. The firm union of parts also secures 

 return to their original position when the pressure is removed. Besides which, access 

 to the nectar is only permitted to a select number of powerful insects. Bees pos- 

 sessing the requisite strength, however, are scarce, and visitors of this species are 

 consequently few in number. Although the majority of flowers remain unvisited, 

 they are just as fertile when self-pollinated as when crossed (Ogle, Miiller, Kerner). 



Visitors. — In the course of four summers, Herm. Miiller only observed 3 bees : — 

 I. Eucera longicornis Z.; 2. Halictus sexnotatus K. 5, skg. and po-cltg., 5, skg. ; 

 3. Megachile pyrina Lep., do. 



A. Schulz noticed flowers perforated by humble-bees. 



Alfken saw 2 bees, skg., at Bremen. — i. Anthidium manicatum /*. 5; 2. Mega- 

 chile maritima K. 5. 



230. Lathyrus L. 



Nectar-containing bee flowers with a stylar brush. 



781. L. pratensis L. (Delpino, 'Ult. oss.,' pp. 55-9; Herm. Muller, 'Ferti- 

 lisation,' pp. 207-10, 'Weit. Beob.,' II, p. 257, ' Alpenblumen,' p. 249; Schulz, 

 'Beitrage,' II, p. 211 ; Lindman, ' Bidrag till Kanned. om Skandin. Fjellvaxt. Blomn. 

 o. Befrukt.'; MacLeod, Bot. Jaarb. Dodonaea, Ghent, vi, 1894, pp. 362-4; Loew, 

 'Bliitenbiol. Floristik,' p. 395 ; Knuth, ' BI. u. Insekt. a. d. nordfr. Ins.,' p. 201, 'Weit. 

 Beob. ii. Bl. u. Insekt. a. d. nordfr. Ins.,' p. 233.) — The mechanism of the yellow 

 flowers of this species, which was first described by Delpino, and afterwards more 

 fully by Hermann Muller, is similar to that of Pisum. The union of alae and carina 

 with the sexual column is effected by two long vesicular alar processes. These 

 run backwards, and rest upon the column, their tips meeting in the middle line. 

 Their elasticity brings about the return of the carina to its original position, on 

 removal of the pressure exerted by an insect visitor. On either side the end of the 

 carina there is a sacculation, bounded behind by a deep fold, and opening only at 

 the carinal tip. These two sacculations jointly enclose all the anthers in the bud ; 

 dehiscence takes place at the beginning of anthesis. The style is almost vertical, 

 and expands beneath the oval terminal stigma into an elongated oval plate. The 

 inner side of this is beset with short hairs directed obliquely upwards, which sweep 



