1894.] Species of Medicago L. in England. 145 



Lepidoptera : — Rhopalocera: — 

 10. Pieris brassicae L. abundant. 11. P. rapae L. 

 12. P. napi L. 13. Vanessa urticae L. 



14. Polyommatus phloeas li. 15. Lyccena icarus Ju. 



Heterocera : — 



16. Triphaena pronuha \j. 17. Plusia gamma h. 



18. Strenia clathrata L. 



Coleoptera: — 19. Meligethes viridescens F. 

 Diptera: — Syrphidae : — 



20. Platychwus mamcatus Mg. 21. P. alhimanus F. 



22. P. scutatus Mg. 23. Byrphus halteatus Deg. 



24. 8. coroUae F. 25. 8. ribesii L. 



26. Sphaerophorea scripta h. 27. Erystalis pe^^tinax Scop. 



28. Myiatropa Uorea L. 29. Syritta pipiens L. 



Muscinae : — 30. Lucelia sericata Mg. 

 Anthomyidae : — 31. Caricea tigrina F. 



Act of Fertilisation. Of these insects all seek honey, but the 

 flies seem rarely to obtain it and cannot obtain pollen while 

 the flower is unexploded. As Mtiller and Henslow have already 

 observed, the Hive bee does not explode the flower, but inserts its 

 proboscis obliquely over the basal processes and not between them. 

 It is necessary to produce explosion for an insect to insert its 

 proboscis between these basal processes; — any outward movement 

 imparted to them is imparted to the combining processes, and the 

 flower explodes. Mtiller attributed the work of fertilisation to 

 butterflies, but never saw the act. Urban disqualifies these insects 

 on account of the flexibility of their probosces ; and my observa- 

 tions lead to the same view. I have watched several hundred 

 separate butterfly visits, often at very close distances, and have 

 never seen these insects cause any explosion. Bombus generally 

 sucks like Apis, sometimes visiting the flower first on one side, 

 and then on the other, like a Dicentra flower. But on one very 

 hot afternoon I observed B. hortorum in the act of ex- 

 ploding the flowers in great numbers, and on two occasions 

 I have seen Apis deliberately exploding the flowers. I have 

 not seen the calyx bitten through by Bombus, but such has 

 been recorded \ 



When the flower is exploded the stamens free themselves with 

 a jerk which scatters the pollen ^, some of which will adhere 

 to the insect and some may fall into neighbouring flowers. If the 

 stigma strikes the insect's body but obtains no pollen, there still 



^ Schulz, A. Beitrage zur Kenntniss d. Bestaubungseinrichtungen u. Ge- 

 schlechtsvertheilung bei den Pflanzen. Cassel, Heft ii. p. 208, 1890. 

 " Cf. De CandoUe, Physiologie, loc. cit. 



VOL. VIII. PT. III. 11 



