GERANIACEAE 231 



presence of, the desired secretion. When, however, insects have once found 

 the nectar in a flower possessing guides, it is easy for them to discover it in flowers 

 of the same species devoid of guides. But the various flower-forms of Erodium 

 cicutarium somewhat limit Sprengel's theory of nectar-guides (' Entd. Geh.,' 

 pp. 15, 16), since they show that these — though helping insects to find nectar — 

 are not absolutely necessary, it being sufficient if a certain number of blossoms 

 possess them. 



Loew summarizes as follows the results he obtained by studying the flower- 

 pollination of Erodium cicutarium (' Bliitenbiol. Florislik,' p. 212). — The absence 

 or presence of nectar-guides is not an essential distinction between the autogamous 

 and allogamous varieties, nor are these markings restricted — as Ludwig maintained — 

 to pimpineUifolium. Both great varieties of the species present various stages between 

 allogamy and autogamy, differing chiefly in their feebler or stronger protandry, 

 smaller or larger flowers, and possession of actinomorphy or zygomorphy. 



Besides the hermaphrodite flowers, Schulz has observed unisexual ones, distributed 

 gynodioeciously and gynomonoeciously, or androdioeciously and andromonoeciously. 



Warnstorf describes the flowers as protogynous, and adds the following. — The 

 stamens are shorter than the styles, so that self-pollination is prevented. In 

 the small-flowered variety (at Ruppin) the petals are usually not blotched at the 

 base, but the two upper ones, which are smaller and of a deeper red than the others, 

 frequently have the yellowish basal blotch that is characteristic of the large-flowered 

 variety. In the latter there may be, though rarely, three to four blotched petals. 

 In the smaller flowers the stamens are often vestigial, so that female stocks occur. 

 The stigma is purple, rose-coloured, or pale yellow. 



Visitors. — Sprengel saw humble-bees and the honey-bee. In the island of 

 Rom, I noticed a hover-fly (Helophilus pendulus Z.), remarkably freq., and I have 

 seen other hover-flies in Fohr and at Kiel, as well as short-tongued bees. 



Herm. Muller gives the following list. — 



A. Coleoptera. Coccinellidae : i. Coccinella septempunctata Z., nect-lkg. 

 B. Diptera. {a) Conopidae : 2. Myopa buccata Z., skg. (p) Muscidae : 3. Calliphora 

 vomitoria Z., skg. ; 4. Lucilia cornicina F., do. ; 5. L. sp., do. (c) Syrphidae : 

 6. Rhingia rostrata Z., skg. ; 7. Syritta pipiens Z., do. C. Hymenoptera. [a) 

 Apidae : 8. Andrena gwynana K. $, skg. (Thuringia) ; 9. A. parvula K. 5, do. ; 

 10. Apis mellifica Z. 5, skg. and po-cltg. ; 11. Halictus cylindricus F. j, skg.; 

 12. H. leucozonius Schr. 5, do.; 13. H. nitidiusculus K. j, do.; 14. Sphecodes 

 ephippius Z., do. (b) Sphegidae: 15. Ammophila sabulosa Z., skg. D. Lepidoptera. 

 Rhopaloccra : 16. Pieris napi Z., skg. persistently; 17. P. rapae Z., do. 



Verhoefif observed the following in Norderney. — 



A. Coleoptera. {a) Nitidulidac -. i. Meligethes aeneusZ'.,po-dvg. B. Diptera. 

 (a) Muscidae: 2. Anthomyia sp. ; 3. Miltogramma sp., po-dvg. (b) Syrphidae: 4. 

 Melithreptus menthastri Z. C. Hymenoptera. (a) Chrysididae: 5. Holopyga 

 amoenula Z'«M. [b) Pteromalidae: 6. Pteromalus sp. [c) Sphegidae: 7. Oxybelus 

 uniglumis Z., skg. 



Loew saw Apis mellifica Z. $, skg., in Silesia (' Beitrage,' p. 25); as did also 

 H. de Vries in the Netherlands (Ned. Kruidk. Arch., Nijmegen, 2. ser., 2. deel, 1875). 

 MacLeod observed Apis, a humble-bee, 2 short-tongued bees, 3 hover-flies, 3 Muscidae, 

 and a Lepidopterid in Flanders (Bot. Jaarb. Dodonaea, Ghent, vi, 1894, pp. 236-7). 



