The problem of the method of pollen moistening is somewhat more complicated in the case of flowers which furnish an excessive supply. Under such conditions the entire ventral surface of the collecting bee becomes liberally sprinkled with pollen grains which either will be removed and dropped or will be combed from the bristles and branching hairs, kneaded into masses, transferred, and loaded. The question naturally arises whether the movements here are the same as when the plant yields but a small amount of pollen which is collected by the mouthparts and anterior legs. In the opinion of the writer they are essentially the same, except for the addition of cleansing movements, executed chiefly by the middle and hind legs for the collection of pollen which has fallen upon the thorax, upon the abdomen, and upon the legs themselves. Indeed it is questionable as to just how much of this plentiful supply of free pollen is really used in forming the corbicular masses. Without doubt much of it falls from the bee and is lost, and in cases where it is extremely abundant and the grains are very small in size an appreciable amount still remains entangled among the body-hairs when the bee returns to the hive. Yet it is also evident that some of the dry pollen is mingled with the moistened material which the mouthparts and forelegs acquire and together with this is transferred to the baskets.

In all cases the pollen-gathering process starts with moist pollen from the mouth region. This pollen is passed backward, and in its passage it imparts additional moisture to those body regions which it touches, the brushes of the fore and middle legs, the plantæ of the hind legs, and the hairs of the breast which are scraped over by the fore and middle leg brushes. This moist pollen, in its passage backward, may also pick up and add to itself grains of dry pollen with which it accidentally comes in contact. Some of the free, dry pollen 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 corbiculæ 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 plantar 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 addition of a considerable amount of dry pollen gives exactly this result, for the corbiculæ 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 supposition that this moisture is transferred to them from the mouth. In this moistening process my observations show that the fluid concerned 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 plantæ 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."

In describing pollen manipulation several writers state that dry pollen is picked up by the brushes of the legs and is carried forward to the mouth, there moistened (according to some, masticated), and is then carried backward by the middle legs for loading. Obviously such accounts do not apply to cases in which all of the pollen is collected by mouthparts and forelegs. Do they apply in cases where much pollen falls on the body and limbs? Without doubt a certain amount of this free pollen is brought forward when the middle legs, bearing some of it, sweep forward and downward over the forelegs, mouthparts, and breast. However, it does not appear to the writer that this dry pollen is carried to the mouth for the specific purpose of moistening it, or that it is essential to its moistening that it be brought in contact with the mouth. Some of it touches the moist hairs on the forelegs and breast and is moistened by contact. All that remains on the brushes of the middle legs secures moisture from these brushes or from wet pollen which the brushes collect from the mouthparts or forelegs. The supposed necessity of carrying forward pollen to the mouth for moistening is a delusion. Some is accidentally brought forward and into contact with the mouth and gets wet, but the process is not essential.

If the pollen which bees transport to their hives has been moistened with some fluid substance which causes the grains to cohere, this addition should be indicated by differences in the results of an analysis of pollen from a plant as compared with that found in the corbiculæ of a bee which has been working on this plant. For the sake of determining this difference and in an endeavor to ascertain, if possible, the approximate nature of the added fluid, analyses were made of three kinds of pollen, as follows: (1) Pollen collected by hand from the corn plant itself; (2) pollen taken from the corbiculæ of bees which had secured their supply from corn; (3) pollen stored in the cells of the hive. In the first two cases pollen from the same species of plant (corn) was used. The material from the cells of the hive was composed largely of corn pollen, but contained an admixture of some other pollens.

The writer is indebted to Dr. P. B. Dunbar, of the Bureau of Chemistry, for the following analyses:

Pollen direct
from corn.		Corn pollen
from corbicula.		Stored pollen
from hive.
Total solids53.4766.9479.66
Moisture46.5333.0620.34
Reducing sugar before inversion2.8711.0717.90
Sucrose2.773.062.25
Total reducing sugar after inversion5.7914.2920.27
Dry basis:
Reducing sugar5.3716.5422.47
Sucrose5.184.572.82
10.5521.11·····