ADDlTIOiSTAL DETAILS OP BASKET-LOADING PROCESS. 21 



the planta is flexed the auricle is raised and its surface approaches 

 the distal end of the tibia, its inner edge slipping up along the pecten 

 spines and its outer hairy edge projecting into the opening which 

 leads to the pollen basket. (See fig. 8, h.) With each upward stroke 

 of the auricle small masses of pollen which have h^en scraped from the 

 plantar combs by the pecten are caught and compressed between the 

 spiny surface of the auricle and the surface of the tibia above it. 

 The pressure thus exerted forces the pasty pollen outward and up- 

 ward, since it can not escape past the base of the pecten, and directs 

 it into the entrance to the corbicula. The outward and upward slant 

 of the auricular surface and the projecting hairs with which the outer 

 edge of the auricle is supplied also aid in directing the pollen toward 

 the basket. Sladen (1911) states that in this movement the weak 

 wing of the auricle is forced backward, and thus allows the escape of 

 pollen toward the basket entrance, but this appears both doubtful and 

 unnecessar}', since the angle of inclination of the auricular surface 

 gives the pollen a natural outlet in the proper direction. 



If the corbicula already contains a considerable amount of pollen 

 the contributions which are added to it at each stroke of the auricle 

 come in contact with that already deposited and form a part of this 

 mass, which increases in amount by continued additions from below. 

 If, however, the corbicula is empty and the process of loading is just 

 beginning, the first small bits of pollen which enter the basket must 

 be retained upon the floor of the chamber until a sufficient amount 

 has accumulated to allow the long overcurving hairs to offer it effec- 

 tive support. The sticky consistency of the pollen renders it likely 

 to retain contact with the basket, and certain structures near the 

 entrance give additional support. Several small sharp spines, seven 

 or eight in number, spring from the floor of the basket immediately 

 within the entrance, and the entire lower edge of the corbicula is 

 fringed with very small hairs which are branched at their, ends. 

 (See fig. 3.) One large hair also springs from the floor of the basket, 

 somewhat back from the entrance, which may aid in holding the 

 pollen, but it can not function in this manner until a considerable 

 amount has been collected. 



As the pollen mass increases in size and hangs downward and back- 

 ward over the pecten and auricle it shows upon its inner and lower 

 surface a deep groove which runs outward from the entrance to the 

 basket. (See fig. 9, h.) This groove results from the continued im- 

 pact of the outer end of the auricle upon the pollen mass. At each 

 upward stroke of the auricle its outer point comes in contact with 

 the stored pollen as soon as the mass begins to bulge backward from 

 the basket. 



Although the process is a rather delicate one, it is entirely pos- 

 sible so to manipulate the hind legs of a recently killed bee that the 



