DIPS ACE A E 559 



to short-tongued insects. The pollen is also easily secured. In the first (male) 

 stage the stamens of the hermaphrodite flowers project 4-5 mm. from the corolla, 

 and the anthers turn their pollen-covered sides upwards. The stamens mature 

 successively, so that this first stage lasts for several days. After all the stamens have 

 completed their cycle of development, the anthers drop off and the filaments shrivel. 

 The style, so far concealed in the mouth of the corolla, now grows to such an extent 

 that the maturing stigma projects from the flower as far as the stamens did at first. 

 Although the individual flowers develop centripetally, the elongation of the styles and 

 the maturation of the stigmas only begin when all the stamens of the head have 

 withered, so that the entire inflorescence is at first purely male, and then purely 

 female. Insect visitors, therefore, when creeping over a capitulum either get dusted 

 ■with abundant pollen or else pollinate numerous stigmas during a single visit. 

 Automatic self-pollination is not entirely excluded, for as the styles elongate some 

 stigmas come into contact with the anthers of their florets. 



Warnstorf describes the pollen-grains (examined in water) as almost spherical, 

 white, quite opaque, with 3 large germinating processes, up to 137 /a in diameter. 



Besides stocks with hermaphrodite flowers, there are often some with female 

 ones, especially at the beginning of the flowering season. The stamens of these are 

 more or less reduced. The diameter of the inflorescence is usually as great as in 

 hermaphrodite stocks, but in some female plants it is scarcely 2 cm. 



MacLeod (Flanders) and Charles Darwin (Kent) noticed gynodioecism. Willis 

 says that in Cambridgeshire female stocks are commoner than hermaphrodite ones. 



Besides plants with female flowers, Lindman observed on the Dovrefjeld 

 a variety with shorter styles, vestigial stamens, and enlarged actinomorphous 

 corollas (var. isanlha L. M. Neumann). This modification is apparently due to 

 a fungus. 



Visitors. — The most important one is a bee, Andrena hattorfiana F., which 

 devotes itself almost exclusively to Knautia. It is everywhere associated with this 

 species. I observed it in Thuringia, Sylt, Fohr, Schleswig-Holstein, Mecklenburg, 

 and also in Rfigen, where I captured 6 individuals one warm forenoon. 



I also observed the following in Schleswig-Holstein (S.-H.) and RUgen (R.). — 

 A. Coleoptera. All po-dvg. : (a) Cerambyddae : i. Strangalia melanura Z. 

 (R.). {b) CurcuUonidae: 2. Miarus campanulae L. (S.-H.). (c) Nitidulidae : 

 3. Meligethes aeneus F. (S.-H.). B. Diptera. (a) Conopidae: 4. Sicus ferrugineus 

 Z., very common, po-dvg. (R.). {b) Empidae: 5. Empis livida Z., po-dvg. (S.-H.); 

 6. E. opacaZ^. do. (S.-H.); 7. E. tessellata i^. do. (S.-H.). (f) Muscidae : 8. Aricia 

 incana Wi'ed. po-dvg. (S.-H.); 9. Dexia canina F. do. (R.) ; 10. Small Muscids, do. 

 (S.-H.). (d) Syrphidae : all skg. and po-dvg. : 11. Eristalis anthophorinus Zett. S and 5 

 (R.); 12. E. arbustorum Z. (S.-H.); 13. E. horticola Deg. (S.-H., R.) ; 14. E. 

 intricarius Z. (S.-H., R.); 15. E. nemorum Z. (S.-H.); 16. E. pertinax Scop. 

 (S.-H.); 17. E. rupium F. (S.-H.); 18. E. sepulcralis Z. (R.); 19. E. tenax Z. 

 (S.-H., R.); 20. Helophilus pendulus Z. (S.-H.); 21. H. trivittatus F. (S.-H.); 

 22. Sericomyia borealis Fall. S (R.); 23. Syritta pipiens Z. (S.-H.); 24. Syrphus 

 pyrastri Z. 5 (R-) ; 25. S. ribesii Z. (S.-H.); 26. Volucella bombylans Z. 5 and S, 

 and the var. plumata Mg. (R., S.-H.). (e) Tabanidae: 27. Haematopota pluvialis Z. 

 (R.). C. Hemiptera. 28. Calocoris roseomaculatus Deg. (S.-H.). D. Hymeno- 

 ptera. Apidae: 29. Andrena gwynana K. (S.-H.); 30. Apis mellifica Z. 5> very 

 common (S.-H., R.) ; 31. Bombus agrorum F. 5 (S.-H., R.); 32. B. distinguendus 

 Mor. (S.-H.); 33. B. hortorum Z. (S.-H.); 34. B. lapidarius Z. 5 and 5 (S.-H., R.); 



