66 ANGIOSPERMAE—DICOTYLEDONES 



so that ' legitimate ' union is regularly effected. As the head of a humble-bee, about 

 5 mm. in length, can be entirely thrust into the corolla-tube of either sort of flower, 

 a proboscis 1 2 mm. long is able to probe the longest tubes, while one not less than 

 7 mm. can suck all the nectar from flowers with the shortest tubes. 



Legitimate crossing is regularly eff'ected, not only by humble-bees, but also by 

 the brimstone butterfly (Rhodocera rhamni Z.). The first observation regarding it 

 was made by A. Miilberger, of which Hermann Miiller says : ' In my Black Forest 

 valley (Herrenalb) Primula elatior is the first, and for a long time the only hunting- 

 ground, where it can disport itself. It visits the long- and short-styled forms 

 apparently without discrimination. The flower and the butterfly are usually of 

 precisely the same yellow colour. In a short-styled flower it is generally easy to see 

 if it has or has not been visited by a butterfly. In the former case a small hole 

 formed by the proboscis is seen between the anthers which exactly fill the mouth of 

 the corolla-tube.' Miiller has seen this butteifly as a visitor at Lij>pstadt and at Kiel 

 (21. 3. '96). I have noticed it flying industriously from flower to flower. The mark 

 left by the inserted proboscis is always easily detected. As an equally frequent 

 visitor I saw Bombus hortorum L. 5. Both the insects visited with equal zeal the 

 three associated species (P. elatior, P. oflicinalis, P. vulgaris), so that they effected 

 hybridization as well as crossing. 



Flowers which have been perforated by humble-bees (Bombus terrester Z.) just 

 above the calyx are not infrequently to be seen. 



Visitors. — Vide supra. Herm. Miiller observed a humble-bee and a hover-fly 

 in the Alps, and gives the following list for Lippstadt. — 



A. Coleoptera. Slaphylinidae : i. Omalium florale Payk., freq.. creeping about 

 in the flowers. B. Diptera. Bombyliidae : 2. Bombylius discolor i)/^., freq., skg. ; 

 3. B. major Z., much rarer, not as a rule getting at the nectar. C. Hymenoptera. 

 Apidae: 4. Andrena gwynana A'. 5, freq., po-cltg. on the short-styled flowers, but 

 leaving the long-styled ones at once ; 5. Anthophora pilipes F, 5 and S, very numerous, 

 skg. legitimately and po-cltg.; 6. Apis mellifica Z. 5. casually skg. ; 7. Bombus 

 confusus Schenck 5, skg. legitimately; 8. B. hortorum Z. § and 5, very numerous, 

 skg. legitimately, and po-cltg.; 9. B. lapidarius Z. 5, skg. legitimately; 10. B. 

 sylvarum Z. $, do.; 11. B. terrester Z., perforating the corolla-tubes and stealing 

 nectar ; 12. Osmia rufa Z. S, casually skg. 



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



MacLeod (Belgium), 2 long-tongued bees, skg. legitimately (Anthophora pilipesZ'., 

 and Bombus hortorum Z.), a short-tongued bee (Andrena gwynana K. 5, po-cltg.), and 

 the honey-bee, skg. for a short time ; also the humble-bee Bombus terrester Z., 

 perforating the flowers. Alfken (Bremen), 6 bees — i. Andrena cineraria Z. 5; 

 2. Bombus agrorum Z". 5 ; 3. B. hortorum Z. }; 4. B. pratorum Z. 5; 5. Osmia 

 rufa Z. S ; 6. Podalirius acervorum Z. S. 



1814. P. officinalis Jacq. ( = P. veris, var. offidnah's). (Darwin, 'Forms of 

 Flowers,' p. 14; Hildebrand, ' D. Geschlechts-Vert. b. d. Pfl.,' p. 34; Herm. 

 Miiller, ' Fertilisation,' p. 385, ' Weit. Beob.,' Ill, p. 65 ; Kirchner, ' Flora v. 

 Stuttgart,' p. 534, 'Beitrage,' p. 51 ; Schulz, ' Beitrage,' II, pp. 141-2 ; Ljungstrom, 

 'Fine Primula-Exkursion nach Moen' ; Loew, 'Bliitenbiol. Floristik,' p. 392 ; Knuth, 

 'Bloemenbiol. Bijdragen'; Weiss, New Phytol., London, iii, i904,p. 168.) — This species 

 bears heterostylous flowers belonging to class HhL. Their mechanism is the same as 



