82 ALFALFA AND BEES. 



the aid of the processes of the alse (c2), nor are the latter sufficient 

 after section of the carina. Explosion can therefore be effected 

 equally well by separating the anterior pouches, by separating the 

 digitiforra processes, or, finally, by depressing the ala3 and carina. 



If an insect inserts its proboscis in the middle line between the an- 

 terior pouches and the digitiform processes, or if it stands upon the 

 alse and thrusts its head in the middle line under the vexillum, in 

 either case explosion follows. The stigma ( c 5} projects beyond the 

 anthers, and, therefore, is the first to strike the under surface of the 

 bee's body or proboscis ; an instant later the anthers come in contact 

 with an area close around the spot that the stigma touched, dusting it 

 with fresh pollen. The first flower that the insect visits is, of course, 

 not cross-fertilized, but as the bee withdraws from the flower, self- 

 fertilization inevitably occurs. Self-fertilization is undoubtedly effi- 

 cient, for Hildebrand has shown that flowers which wither unexploded 

 when insects are excluded produce seed by self-fertilization. The 

 same author finds two imperfections in the mechanism. One is the 

 possibility of the insect securing the nectar without exploding the 

 flower ; the other is that the flower continues to secrete honey after 

 it has been fertilized. This certainly is much in its favor as a honey 

 plant, though somewhat against the visitation of other unfertilized 

 flowers. 



In the case of the alfalfa, however, it will be seen that the stigma 

 of the ovary is higher than the pollen producing anthers, so that the 

 grains of pollen may all drop to the base of the flower and the ovary 

 go unfertilized; such being the case, no seed would be formed. Small 

 forms resembling seed might be found within the ovary at maturity, 

 but these, not being fertilized, would not germinate. 



From the shape and size of the alfalfa blossom, it is not probable 

 that cross-fertilization could be safely accomplished by means of cur- 

 rents of air. 



It becomes evident, then, that outside agencies must be called upon, 

 and the plant must provide for these agencies. The agents in this 

 case we find to be insects, and the reward offered by the plant for 

 favors rendered is a sweet drop of nectar; that is, the flower in an 

 enticing way places a tempting sip of nectar in such a position that 

 when the insect has favored the flower with a few grains of pollen un- 

 consciously brought from an adjoining flower and just as uncon- 

 sciously left, the coveted sip may be enjoyed. It is evident, however, 

 that the first flower visited will not be cross-fertilized. 



INFLUENCE OF BEES UPON THE SEED CROP. 



It is well known to every stock-breeder that in-and-in breeding will 

 soon cause the strain to deteriorate, and that infusions of new life are- 



