94 ANGIOSPERMAE—DICOTYLEDONES 



pollinia are introduced into one of the slits of another flower, and effect cross- 

 pollination, while at the same time another clip affixes itself. 



The development of the pollinia was investigated by Corry. He also found 

 that flowers are infertile not only with their own pollen, but also with that derived 

 from plants raised vegetatively from the same stock. Pollination is fully effective 

 only when it takes place between flowers belonging to plants grown from the seeds 

 of different stocks. Stadler worked out the histological details of the secretion of 

 nectar, and found that this is produced not only within the petaloid cucuUi, but also 

 by internal nectaries on the inner wall of the stigmatic chamber. The approximated 

 lovi^er edges of the slits serve as nectar-covers for the latter. 



Visitors. — Sprengel observed a fly with clips attached to one of its legs. Herm. 

 Miiller (' Fertilisation,' p. 399) gives the following list of insects observed by himself 

 (H. M.) in Thuringia, Buddeberg (Budd.) in Nassau, Hildebrand (H.) at Freiburg, 

 and Delpino (D.) at Florence, to which are added some others chiefly noticed by him 

 in his garden at Lippstadt (op. cit., p. 400, ' Weit. Beob.,' Ill, p. 61). Those with 

 clips attached to their claws are indicated by an asterisk (*). — 



A. Diptera. (a) Empidae: i. Empis livida Z., skg., drawing out the pollinia. 

 (^) Muscidae : 2. Lucilia sp., do. (H. M., Westphalia and T.) ; 3. Ocyptera brassicaria 

 F. (H.). (f ) SyrpUdae : 4.* Eristalis arbustorum L. (H. M., T.) ; 5.* E. nemorum Z. 

 (H. M., T.); 6.* E. tenax Z. (H. M., T.) ; 7. Melithreptus scriptus Z., skg., without 

 putting its feet in the slits (H. M., T.) ; 8. M. taenialus Mg., do. (H. M., T.). 

 B. Hymenoptera. (a) Apidae: 9.* Apis mellifica Z. 2 (H. M., T. ; D.); 10. 

 Bombus agrorum F. 5, freq., skg. and pollinating (H. M., WiirzlDurg); 11.* B. 

 hypnorum Z. 5 (Budd.) ; 1 2.* B. italicus Z. (D.) ; 1 3.* B. terrester Z. (J and S (Budd.) ; 

 14.* Coelioxys conoidea ///. 5 and S, freq., skg. and pollinating (H. M.) ; 15.* C. sp. 

 5 and S (Budd.) ; 16.* Halictus cylindricus F. J (Budd.) ; 17.* H. quadricinctus F. 5 

 (Budd.); 18.* H. scabiosae Rossi 5 (Budd.); 19. Several small sps. of Halictus, 

 which never put their feet in the slits (H. M.) ; 20.* Stelis aterrima Pz. 5 (Budd.). 

 {V) Formicidae: 21. Different sps., caught in the slits (H. M., T.); 22. Myrmica 

 levinodis Nyl. 5, do. (H. M.). (c) Sphegidae : 23.* Ammophila sabulosa Z. $ (Budd.) ; 

 24.* Scolia hirta Sc/ir. (D.); 25.* S. flavifrons F. (D.); 26.* S. quadripunctata F. 5 

 (Budd.); 27.* Psammophilaaffinis .A'. 5(Budd.). {d) Vespidae : 28.* Polistes diadema 

 Ltr. (H. M., T.); 29.* P. gallica Z. ? (H. M., T. ; Budd.). C. Lepidoptera. 

 Nociuidae : 30. Hypena proboscidalis Z., skg., but not drawing out the polHnia 

 (H. M.) ; 31. Plusia gamma Z., do., in the evening (H. M.). D. Neuroptera. 

 32. Panorpa communis Z., skg., and drawing out the pollinia (H. M.). 



1878. A. fruticosa L. (=Gomphocarpus fruticosus R. Br.). (Sprengel, 

 ' Entd. Geh.,' pp. 139-50.) — Sprengel gives a very thorough account of this species. 

 The flowers smell like honey, and their mechanism agrees with that of A. syriaca. 



Visitors. — Sprengel observed a number of flies and wasps in the castle garden 

 at Charlottenburg (22. 8. '89), with clips attached to their feet. 



1879. A. curassavica L. — This species also was investigated by Sprengel. 

 Fritz Miiller says that in South America, its native country, it is chiefly visited 

 by butterflies, and Hermann Miiller depicts the foot of one of these to which 1 1 clips 

 and 8 pollinia are attached (Fig. 568). 



1880. A. tenuifolia L. — 



Visitors. — Hildebrand saw this species pollinated by a cabbage white, Pieris 

 brassicae Z. (Bot. Ztg., Leipzig, xxix, 1871, p. 746). 



