SCROPHULARINEAE 171 



they may effect either cross- or self-pollination. Harm. Miiller saw smaller bees 

 (Halictus sp.) flying from flower to flower, but immediately turning away from 

 those still closed, till they came to old ones which gaped a little in fading. Into 

 these they made their way, but such visits were of no use to the plant. Schulz 

 says that the humble-bee Bombus terrester L. sometimes perforates the spur and 

 steals the nectar, though he also often saw it sucking legitimately. Automatic 

 self-pollination is possible, but less effective than cross-pollination. Darwin says 

 that this species is sometimes sterile, sometimes self-fertile : that the red variety 

 is twice as fertile when insect-visits take place as when they are excluded : that 

 self-fertilization is more common in the white variety than the red : and that the 

 peloric form is completely fertile when artificially self-pollinated. 



Herm. Miiller records the following 8 bees for Westphalia and Thuringia. — 



I. Anthidium manicatum Z. 5; 2. Bombus agrorum F.; 3. B. hortorum Z. ; 

 4. B. lapidarius Z. ; 5. B. sylvarum Z. ; 6. B. terrester Z.; 7. Megachile fasciata 

 Svi. t ; 8. Osmia L. 5. 



Miiller makes the following remarks about these bee-visitors : ' The females 

 and workers [of the 5 humble-bee species], and in late summer the males also, 

 creep bodily into the flower, and creep out backwards dusted on their backs with 

 pollen. From time to time they brush off the adhering pollen from their thorax 

 with the tarsal brushes of the fore or midlegs, and from the abdomen with the 

 tarsal brushes of the hindlegs. Not only the females and workers, but the males 

 also, perform this action, which seems, therefore, to be done more for cleanliness 

 than to collect the pollen, though the females and workers naturally make use of 

 it, placing it in the pollen-baskets on their hindlegs. I have also seen Anthidium 

 manicaium L. 5, Megachile fasciaia Sm. S, and Osmia rufa L. 5, creep into the 

 flower and emerge with their backs covered over with pollen. Smaller bees only 

 exceptionally creep into still fresh flowers, and are useless to the plant : I have 

 only once seen Megachile centuncularis L. 5 succeed in entering ; on the other 

 hand I have repeatedly seen small species of Halictus (H. zonulus Sm. 5, H. morio 

 F. 5, H. Smeathmanellus K. 5) flying from flower to flower until they reached an 

 old flower, which in withering had opened slightly and permitted them to enter. 

 This showed clearly how far the fast closure of the mouth is useful to the plant ; 

 if the small bees could enter from the first, they would use up much of the honey, 

 and the flowers would be less diligently visited by the humble-bees.' 



The following were recorded by the observers, and for the localities stated. — 



Knuth (Schleswig-Holstein), 4 humble-bees all skg. legitimately — i. Bombus 

 agrorum F. 5 and 5 ; 2. B. hortorum Z. $, 5 and $ ; 3. B. lapidarius Z. 5 and 5 ; 



4. B. terrester Z. 5, 5 and S. Loew (Berlin Botanic Garden), the humble-bee 

 Bombus agrorum F. 5, skg. Douglas, 5 bees (Ent. Mag., London, xxiii, 1886) — 

 I. Apis mellifica Z. 5; 2. Bombus derhamellus K. 5 and 5; 3- B. terrester Z., var. 

 lucorum Z. 5 ; 4- B. terrester Z., var. audax Harr. (=B. virginalis Fourcr.) 5 and g; 



5. Megachile centuncularis Z. Neumann recorded Nos. 2, 3, and 5 of these as 

 far back as 1850. Schletterer (Tyrol), the humble-bee Bombus lapidarius Z. 

 P. Magnus (Natw. Rdsch., Braunschweig, vi, 1891, p. 20) noticed that humble-bees 

 were able to suck for a longer time when they did so legitimately than when they 

 perforated the flowers, and this may be regarded as an adaptation to the visits of 

 these insects. 



