Ij6 BOTANICAL GAZETTE. [ July, 



rise, and the only action which will insure that the pollen 

 shall be applied to the same side of the proboscis which 

 touches the stigma, is that the pollen discharge shall be 

 effected by the bee itself. 



On the part of the visitors, the inversion seems particu- 

 larly favorable to bees of the genus Osmia, and I am in- 

 clined to consider the flowers of V. pubescens, palmata and 

 striata as specially adapted to them, in spite of the presence 

 of other visitors. Now, these bees have their pollen-collect- 

 ing hairs situated on the ventral surface of the abdomen, so 

 that the position which they must take to suck is the one 

 which enables them to receive the pollen and apply it to 

 their scopae most conveniently. For this reason, species of 

 Osmia are the most abundant and most useful visitors. In- 

 deed, for the species referred to, I am convinced that Osmia 

 albiventris and atriventris are of more importance than all 

 of the other visitors put together. Miiller mentions bees of 

 this genus as visitors of V. odorata, canina and tricolor, var. 

 arvensis. — * — 



Delpino (178) 4 has discovered that the beards on the 

 lateral petals are intended for the bee to cling to when it 

 turns head downwards. He rightly regards the bees which 

 reverse as legitimate visitors, and considers the action of 

 Anthophora pilipes on V. tricolor as illegitimate, since it in- 

 serts its proboscis without turning. Really, the proper vis- 

 itors are bees which are small enough to use the bsard as a 

 support ; so that the humble-bees and butterflies may prop- 

 erly be classed as intruders, even when they reverse. For 

 the proper visitors of the bearded violets we must look to 

 small bees, among which the Osmias are most important. 



Remembering that the bearded violets are sternotribe, it 

 is interesting to observe that they become nototribe with re- 

 spect to all visitors, like Anthophora and Bombylius, which 

 tail to reverse, and this enables us to understand *how a prop- 

 erly nototribe violet might be produced. V. pedata is a vio- 

 let of this sort, being visited mainly by long-tongued bees, 

 which light upon the spurred petal and remain upright. The 

 lateral petals have lost their beards, since they are no longer 

 of use to the bees. The flower still retains the upward cur- 

 vature of the spur as an ancestral characer. If the spur had 

 been developed with reference to visitors acting like most of 

 those now seeking it, I think it would curve down rather 



_ * 



! S "™l )eTS in P !irent,1 <*is after an author's name are the numbers of titles in Thomp- 

 son s Bibliography. See Mailer: Fertilization of Flowers, pp. 59U-634. 



