f-OLLEN MOISTENING. 27 



which falls upon the moist brushes or upon the wet hairs of the 

 thorax is also dampened. Some of the dry pollen which is cleaned 

 from the body by the action of all of the legs meets with the wet 

 brushes or with the little masses of wet pollen and itself becomes wet 

 by contact. Pollen grains which reach the corbiculae either dry or 

 but slightly moistened are soon rendered moist by contact with those 

 already deposited. Little pollen gets by the sticky surfaces of the 

 combs of the plantse or past the auricles without becoming thoroughly 

 moist. 



Sladen (1912, c) very aptly compares the mixture of dry pollen 

 with wet to the kneading of wet dough with dry flour and suggests 

 that the addition of dry pollen may be of considerable advantage, 

 since otherwise the brushes, particularly those of the hind legs, 

 would become sticky, " just as the board and rolling pin get sticky 

 in working up a ball of dough if one does not add flour." The addi- 

 tion of a considerable amount of dry pollen gives exactly this result, 

 for the corbiculse then rapidly become loaded with pollen mixed 

 with a minimum supply of moisture and the brushes reniain much 

 dryer than would otherwise be the case. However, if too much dry 

 pollen is added the resulting loads which the bees carry back to the 

 hives are likely to be irregular, for the projecting edges of the masses 

 may crumble through lack of a sufficient amount of the cohesive 

 material by which the grains are bound together. 



On the other hand, it does not appear at all necessary to mix much 

 dry pollen with the wet, nor do the brushes become sufficiently 

 " sticky " from the presence of an abundance of the moistening fluid 

 to endanger their normal functional activity. I have observed bees 

 bringing in pollen masses which were fairly liquid with moisture, 

 and the pollen combs also were covered with fluid, yet the baskets 

 were fully and synunetrically loaded. 



Sladen's different interpretations of the pollen-moistening process 

 are rather confusing, and it is difficult to distinguish between what 

 he states as observed facts and what he puts forward as likely 

 hypotheses. He agrees with me in his observation that all of the 

 legs become moist in the region of their brushes and also in his sup- 

 position that this moisture is transferred to them from the mouth. 

 In this moistening process my observations show that the fluid con- 

 cerned is passed backward by the contact of the middle-leg brushes 

 with the wet foreleg brushes and that the middle-leg brushes in turn 

 convey moisture to the plantae as they rub upon them. I am also 

 convinced that the wet pollen grains furnish additional moisture to 

 the brushes as they pass backward, and this is particularly true in 

 the case of the extremely moist surfaces of the auricles and the pollen 

 combs of the planta, since here moisture is pressed from the pollen 

 upon these areas. The pollen upon the fore and middle leg brushes 

 is not always " dry " even in " a relative sense." 



