THE CANADIAN ENTOMOLOGIST. 353 



THE INFLUENCE OF THE APID^ UPON THE GEOGRAPH- 

 ICAL DISTRIBUTION OF CERTAIN FLORAL TYPES. 



BY J. ARTHUR HARRIS, ST. LOUIS, MO. 



The reciprocal relations of flowers and insects form a subject which has 

 attracted many workers since Darwin and others showed the importance 

 of this phase of biology. In the whole field of adaptation we have no 

 better materials than those afforded by the morphology of flowers and 

 insects considered in their relation to each other. The field has been 

 most exploited by botanists, but some entomologists have also made 

 valuable contributions to the literature of this subject, and their assistance 

 has always been necessary for the identification of visitors observed. 



Ecology, the phase of biology which considers the animal or plant in 

 its relation to its environmental conditions, has been much pursued of 

 recent years. One of the oldest phases, and one which at the present 

 time, it seems to me, is not receiving the attention which it should, is that 

 concerned with the mutual adaptations of flowers and insects. 



The researches of Darwin early showed the importance of the classic 

 studies of Koelreuter, Sprengel and Knight, and other workers immediate-^ 

 ly seized his ideas and proceeded to verify and elaborate them by obser- 

 vation, experiment and comparison. The tracing of the development of 

 the various conceptions concerning the relations of flowers and insects 

 during this most important period in the history of biology is a most 

 fascinating exercise, but one which is quite out of place in this paper. 

 Here we are concerned only with the problem of the influence of the 

 insects upon the geographical distribution of the flora, and we shall make 

 no attempt to go back beyond the classic work of Hermann Miiller on 

 Alpine flowers and their fertilization by insects. 



The basis of the floral theory of Miiller, as developed in the third 

 portion of his Alpenblumen, is the proposition of the beneficial effect of 

 crossing; so often as the progeny of cross-fertilization comes into com- 

 petition for existence with the offspring of self-fertilization, it wins in the 

 contest ; only when the struggle for existence is absent may self fertiliza- 

 tion suffice for long-continued propagation. The supporting evidence for 

 this thesis is two-fold : the direct proof of the extensive cultural experi- 

 ments of Darwin and the indirect evidence yielded by the organization of 

 flowers themselves. 



While the importance of cross-fertilization has doubtless been over- 

 estimated by many writers, it hardly need be stated in this place that at 

 the present time no argument need be advanced in its support. Admitting 



October, 1905. 



