382 The Ohio Naturalist [Vol. XI, No. 8, 



of the nectar pockets arises a curved horn-shaped process that 

 bends inwards over the stigmatic disc. 



"An insect searching for nectar shps about on the smooth 

 flowers which make up the umbel until its feet get a firm hold in 

 the lower part of a slit. When it wishes to go and draws up the 

 leg the claws are guided upwards in the slit so that the clip becomes 

 attached to the foot. During the subsequent movements the 

 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 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 

 in the petal oid cuculli, but also by internal nectaries on the inner 

 wall of the stigmatic chamber. The approximated lower edges 

 of the slits serve as nectar-covers for the latter.' 



The fact of the plants being infertile to their own pollen as 

 well as to pollen from plants raised vegetatively from the same 

 stock probably explains the small number of fertile pods observed 

 later in the season as compared with the large number of flowers 

 originally observed. 



Visitors: Diptera; PoUenia rudis, Lucilla caesar, Chrysopus 

 moercus: Lepidoptera; Harrisina amcricana; Hy- 

 mcnoptera; Microbembex monodoiita. 



Asclepias incarnata (Swamp Milkweed). 



Visitors: Diptera; Peleteria robust a, Midas cahatus, PJior- 

 niia regina, Lucilia sericata, Phthiria sidphurea; 

 Lepidoptera; Anosia plexippiis, Satyrodes eury- 

 dice, Argynnis cybele; Cokoptera; Donaeia pusilla 

 Hymenoptera; Microbembex mouodonta. 



Asclepias tuberosa (Butterfly-weed). 



Visiiovs: Lepidoptera; Ilarrisiiia americaiia, Anosia plex- 

 ippiis; Hymenoptera; Microbembex monodoiita, 

 Xylocopa virginica. 



Bignoniaceae (Bignonia Famih'). 

 Tecoma radicans. In making collections on this plant it was 

 found that most of the visitors had little to do with pollination 

 but were busy collecting some material from the calyx. The nectar, 

 which is secreted at the base of the long corolla-tube is availa- 

 ble to certain insects onh'. The arrangement of the stamens 



^Op. cit., III. 93-94. 



