66 The Botanical Gazette. [March, 



their pollen in a conical mass upon the summit of the style. 

 The style rises to its usual height and holds the pollen where 

 it will easily touch insects lighting upon the globular head of 

 flowers. After the pollen has been removed, the stigma be- 

 comes receptive, and the flower is now in the second or female 

 stage. 



Meehan 1 has taken the loading of the pollen upon the tip of 

 the style as a plain' case of self-fertilization. But it is no more 

 a case of self-fertilization than the loading of pollen upon the 

 style brush of Campanula. As far as they go, Meehans ob- 

 servations do not support the view that self-fertilization occurs 

 even in absence of insects, for he says: 44 Numerous seeds 

 are in every head examined. Carefully dissecting one, I found 

 it had 27!) flowers, of these 225 perfected seeds, and only 54 

 failed." He had made the gratuitous assumption that fullness 

 of fruit is evidence of self fertilization. 2 As between cross 

 and self fertilization, the 225 fruitful cases prove nothing; the 

 failure of one in five flowers is presumptive evidence against 

 the power to self-fertilize. 



The round heads of white flowers are very attractive to in- 

 sects. The corolla tubes are 9 mm. long and are very nar- 

 row, especially below. The flowers are thus adapted to long 

 and thin tongues. The nectar rises in the tube so that shorter 

 tongued insects can reach some of it, but the predominant 

 visitors are butterflies. On 11 days, between July 5th and 

 August 17th, I observed the following- visitors: — 



Hymenoptera — Apidae: (1) Apis mellifica L. Q, s., ab. ; 

 (2) Bombus virginicus Oliv. g, s. and c. p., freq. ; (3) B. sepa- 

 rates Cr. <$?£>, s.,ab. ; (1) H. Ridingsii Cr. 3, s.,one; (5) B. 

 americanorum F. <?£$, s. and c. p., ab. ; (6) B. pennsylvanicus 

 De Geer, $$, s., fn (. ; (7) H. scutellaris Cr. $, s., one; (8) E,m- 



phor bombiformis Cr. ?, s., one; (9) Xenoglossa pruinosa Say 



6, s. ; (10) Melissodes obliqua Say 9, s. ; (11) M. bimaculata 

 St. Karg. 5, s. ; (12) Ceratina dupla Say $, s. ; (13) Megachile 



mendica Cr. ?, c. p.; (14) Nomada texana Cr. $, s. ; Andre- 

 nidae: (15) Halictus Lefouxii St. Farg. ?, s., one ; (16) H. 

 ligatus Say $, s. f one; (17) Agapostemon nigricornis F.'$, s-J 



(18) A. radiatus Say 5, s. ; (19) A. texamis Cr. $, s. ; (20) 

 Prosopis affinis Sm. ?, f. p.; Pompiiidae: (21) Priocnemis ful- 



'Contribution to the Life Histories of Plants. Proc. Acad. Nat Sci Phila , 



1S^ :;J:; 333; \ tigs See also Bull. Torr. i I Club, xv, 54. 



- Hot. Gazette xiii, 1 ■"> ; 



