— 144 — 



To understand the biological signiflcance of the sfcructure of the 

 flower of Commelyna, we must notice the way in which it is 

 visited by insects : 



VisiTORS : 1. The hive-bee {Apis mellifica '5) places itself upon 

 the inferior petal (which is larger tlian the two superior ones, 

 and forms a landing-place for the insect); it catches held of 

 the stamens m- with its legs, draws them inwards, and unin- 

 tentionally dusts its ventral surface with pollen, The style 

 being longer than the stamens m-, thé stigma will be touehed 

 before the anthers m^, and fertilisation with pollen of another 

 flower is favoured. During this process, the hive-bee coUects 

 pollen from the anther m', situated in the middle of the flower, 

 Havingdone that, the bee climbs a step higher on the ladder, 

 loosening the style and the anthers m^, taking hold of the stamen 

 >n3, and in this position itbegins to squeeze the juice out of the 

 connective-lobes of the anthers m' (1) and to coUect the small 

 supply of pollen contained in the goniothecse. Finally, the bee 

 leaves the flower flying upwards (not coming a second time into 

 contact with the reproductory organs of the same flower), and 

 visits a new flower in the same way. Sometimes the bee seeks 

 nectar : it tries to suck honey at the base of the stamens w*, when 

 going to leave the flower (we could not detect honey). 



Sometimes the bee proceeds irregularly in the flowers visited 

 first, but after a few visits it becomes acquainted with the me- 

 chanism, and in the next flowers it accomplishes its work quite 

 regularly in the way described above. 



2. A small black bee {Halictus sp.) collects pollen from m' and 

 afterwards squeezes the juice out of m', but its body is too small 

 to touch the stigma and the anthers m'^ : it cannot produce fertili- 

 sation and is therefore an unbidden guest, 



3. Syritta j)ipiens, trying to cling to m'\ catches hold ofw^^, 

 just as the hive-bee does; itfeeds itself by the pollen ofm%and after- 



(1) Pig. 7 shows an anther wUintoucheJ ; fig- S the same anther after 

 the visit of the bee ; three of its lobes (u, u) have been sqiieezed out (see 

 also fig. 13). 



