292 American Quarterly Microscopical Journal. 



inferior side, reaching to within about one fourth of its length from 

 the apex. This sheath is densely clothed with hairs, regularly- 

 disposed in transverse rows ; these hairs being short and tri- 

 angular in shape near the base of the organ, long and spiny about 

 the middle, smaller and more flexible near the apex. 



Enclosed within the hairy sheath, but not attached to it ex- 

 cept near the apex, is the colorless rod {b) ; this can readily be 

 withdrawn from the open side of the sheath, as shown in Fig. i. 



The proboscis terminates in a hollow cone, or funnel, which 

 serves, no doubt, as a sucking disc. 



The colorless rod is membranous and extremely elastic, and 

 may be greatly expanded by slight pressure, or distended by its 

 contents, and probably, when seen in one of these conditions, has 

 received from some authors the name of "membranous sack." 



In the examination of several hundred sections, I have not 

 found any structure that agrees with the description of the " mem- 

 branous sack." 



The rod is not tubular as described by Mr. Chambers, but has 

 a ^/<f'<?/ ^^;'f(97't' on the lower side (Fig. 3), and this groove, being 

 closed by the infolded edges of the hairy sheath, gives it the ap- 

 pearance of a circular canal, as shown at e, Fig. 2. 



At the back of the rod is a thick layer of muscle (Fig. 3, b)., 

 which serves to enlarge or contract the canal {e), thus making the 

 tongue a sucking organ ; for no doubt the canal can be entirely 

 closed or greatly distended by this powerful muscle. 



The unaccountable presence of hairs in the canal (^), observed 

 by Mr. Chambers, will be readily understood by reference to Fig. 2, 

 in which they are seen projecting into it from the edges of the 

 sheath. 



DESCRIPTION OF PLATE XX. 



The same letters designate corresponding parts in all the figures. 

 Fig. I. The bee's tongue; showing the slit on the inferior side of the sheath, 

 with the colorless rod partly withdrawn. 

 a. Hairy sheath. 

 h. Colorless rod. 

 c. Hollow cone. 

 Fig. 2. Transverse section across the middle of the tongue. X 3<^0- 



e. Groove in the colorless rod. 



f. Curved ends of the folded edges of the sheath. 



Fig. 3. Section of the colorless rod with attached muscle (/'). 



Fig. 4. Hairy sheath showing the manner in which the edges are folded. 



