5S3 TRANS. ST. LOUIS ACAD. SCIENCE. 



SOLANACE^. 



Solanum nigrum L. — The flowers are specially adapted to bum- 

 ble-bee females, which visit them only to collect pollen, which they 

 milk out of the apical chinks of the anthers with their jaws, as in 

 the case of Cassia. Sprengel saw bees and bumble-bees collect- 

 ing pollen. Miiller saw Melithrc'ptics ( = Sphaerophoria) scriptus 

 and Syriita fipiens feeding on the pollen. The visits of these 

 SyrphidcB^ I think, have little significance, since they often visit 

 flowers to which they are not adapted in order to feed upon stray 

 pollen. In Florida, Feb'y 24, 1887, I sav^^ Bombus virginicus 

 Oliv. $ collecting the pollen. In Illinois I saw the flowers visited 

 by Bombus virginicus ^ and by B. americanorum F. ? . 



Solanum Carolincnse L. — Like the preceding, this flower is 

 adapted to bumble-bee females, which visit it only for pollen. I 

 have seen Bombus amcricaitorum F. ^ collecting the pollen. 



Datura Tatula* 'L.. — ("Adv. from trop. Amer.") The flower 

 measures about 1 1 centimetres. The stamens are adherent to the 

 corolla tube for about 40 mm., after which they extend inward 

 to the middle, so that bees are excluded from the honey and only 

 Sphingidce can reach it. I have seen Deilephila lineata F. 

 sucking. 



Hive-bees squeeze into the flower-buds as soon as they begin 

 to open, and collect all of the pollen before the time of flight of 

 hawk-moths. I have seen most of the pollen carried away as early 

 as five o'clock in the afternoon. I have seen the following insects 

 visiting the flower for pollen : 



Hymenoptera. — Apidce, (i) Apis mellifica F. ^ , ab. ; (2) Melissodes 

 perplexa Cr. 9- A7idrenidce, (3) Halictus confusus Sm. ^ — all c.p. 



Diptera. — SyrphidtK. (4) Syrphus ribesii L. ; (5) Allograpta obliqua 

 Say; (6) Mesograpta marginata Say; (7) Rhingia nasica Say — all f.p. 



Coleoptera. — Ckryosmelid'K^ (S) Diabrotica 12-punctata Oliv., f.p. 



Of course all of the insects mentioned above, except the Deile- 

 phila^ must be regarded as intruders. The plant probably de- 

 pends mainly upon self-fertilization and has spread beyond the 

 i"ange of its principal pollinators. The above-mentioned insects 

 may aid in self-fertilization or cross-fertilization, but their visits 

 only result from the flower opening prematurely. 



* On D, Stramonium see Sprengel, 122, and Schulz. Beitrage zur Kenntniss der Be- 

 stabuungseinrichtungen u. d. Geschlechtevertheilung b. d. Pflanzen, 73. 



