114 
GLAND STRUCTURE. 
by means of two circular openings on the hypo- 
pharyngeal plate {schlundbldttchefi) (Fig. 50, a a). 
These openings lead to sac-like hollows {b) noticed 
and described by Wolff (170), and Holz, which lie 
in an oblique direction under the plate. On the 
under side they also have smaller round open- 
ings, leading directly into the ducts {c) of the glands 
