POLLEN 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 corbiculse 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 plants 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 remain 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 symmetrically 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 plantse 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." 
