i68 ANGIOSPERMAE DICOTYLEDON ES 



season, while later on the honey-bee and humble-bees were almost the only visitor 

 Charles Robertson made a similar observation in Illinois, but he also finds that 

 the end of August and beginning of September, when the number of flowers 

 limited, wasps once more become the dominant visitors. On this he remarl 

 'This seems to be significant, for when any flower becomes reduced in numbers,"] 

 its proper visitors are apt to be the last to leave it.' (Trans. Acad. Sci. St. Lot 

 (Mo.), V, 1 89 1, p. 587.) 



This recrudescence of activity on the part of wasp visitors does not usuallj 

 take place in North Germany, since the flowering period is generally at an enc 

 before August. But in 1896, on the 14th of that month, after repeated heavy 

 rains, I noticed a number of fresh blossoms, which were being visited by numerous 

 wasps (Vespa vulgaris Z.), that took no notice of other flowers close by. The nest 

 of these insects was near the place. 



It may further be remarked that the yellow anthers and brownish upper lip 

 present a noteworthy agreement with the colour of the wasps which visit the flowers. 



Herm. Miiller (H. M.) and Buddeberg (Budd.) give the following list. 



Hymenoptera. [a) Apidae: i. Bombus agrorum F. 5 and $, skg. (H. M.); 

 2. B. pratorum L. 5, numerous, skg. (H. M., Fichtelgebirge) ; 3. HaUctus cylindricus 

 F. 5, skg. (Budd.) ; 4. H. flavipes F. S, do. (H. M.) ; 5. H. sexnotatus K, $, in large 

 numbers, skg. and po-cltg. (H. M., Budd.); 6. H. zonulus Sm. J, skg. (H. M.). 

 (^) Vespidae : 7. Hoplopus levipes Shuck. 5, flying about the plants in large numbers, 

 settling on the flowers and skg. (Budd.) ; 8. Vespa germanica F., very common, skg. 

 (H. M., Budd.); 9. V. holsatica F., do. (H. M.); 10. V. media Deg., do. (H. M.); 

 II. V. rufa L. do. (H. M.); 12. V. sylvestris Scop. 5, numerous, skg. (H. M., 

 Bavarian Oberpfalz); 13. V. vulgaris Z., very common, skg. (H. M.). 



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



Herm. Miiller (Alps), the humble-bee Bombus senilis 0. Loew (Berlin Botanic 

 Garden). Hymenoptera. (a) Apidae : i , Apis mellificaZ. 5, steadily skg. and po-cltg.; 

 2. HalictusnitidiusculusA'. 5, po-cltg. {b) Tenthredinidae -. 3. Allantus scrophulariae Z. 

 (f) Vespidae : 4. Vespa germanica F. 5, skg. Knuth (Schleswig-Holstein), the honey-bee, 

 skg., 4 skg. humble-bees (i. Bombus agrorum F."^; 2. B. hortorum Z. 5 ; 3. B. lapi- 

 darius Z. 5 ; 4- B. terrester Z. 5), 2 wasps (Vespa vulgaris Z., and V. germanica ^.), 

 and the po-dvg. hover-fly Syritta pipiens Z. von Fricken in Westphalia (W.) and East 

 Prussia (E. P.), the Curculionid beetles Clonus blattariae F. (E. P.) and C. scrophu- 

 lariae Z. (W., E. P.). Alfken (Bremen), 2 humble-bees, skg. Bombus] hortorum Z. 

 5^, and B. lapidarius Z. 5- Heinsius (Holland), wasps and the humble-bee Bombus 

 agrorum F. 5 (Bot. Jaarb. Dodonaea, Ghent, iv, 1892, p. 76). MacLeod (Flanders), 

 3 humble-bees, one other bee (Halictus sp.), and 3 true wasps (op. cit., v, 1893, 

 p. 342). Plateau (Flanders), the wasp Vespa holsatica F., and the honey-bee. 

 Scott-Elliott (Dumfriesshire), 2 humble-bees, a true wasp, and a saw-fly. Saunders 

 (England), the bee Halictus sexnotatus A'., rare. 



ao6i. S. vemalis L. (Wamstorf, Verh. bot. Ver., Berlin, xxxviii, i896.)-4|l 

 The flower mechanism of this species agrees essentially with that of S. nodosa, 

 but Wamstorf distinguishes between three stages of anthesis, and gives the 

 following account. In the second stage which succeeds the first (female) onfll 

 the two long stamens extend to the stigma or somewhat beyond it, and a* 

 their anthers come to lie below it and dehisce on their under-surfaces autogam_ 

 is rendered very difficult. In the third stage the style bends up and the 

 stamens stretch forward, their anthers being in front of the stigma. The pli 



