116 
GLAND STRUCTURE. 
small, with a mere trace of a duct. Some queens 
seem to have this more developed than others, for 
Schieme iz found in three queens a groove where the 
opening should be on each side; in one of them, 
however, he found this groove only on one side. 
System II. 
This is also situated in the head, and was called 
by Meckel (109) sub-lingual gland {glandula sub- 
lingualis). This system has been described by even 
more investigators than System I., for besides Meckel, 
Leydig, and Siebold, we find it mentioned by Ram- 
dohr (136), Treviranus (163), Dufour (32), and 
Fischer (44). 
The duct which conveys the fluid secretion from 
this gland, as well as from that of System III., has 
its opening in the tongue (Fig. 23, .f), then passing 
through the mentum, and continuing through the neck, 
it passes to the thorax, where it terminates in the 
two branches of System III. From this common duct 
(Fig. 50, D, 0) the glands of System II. branch off, 
forming a cross with it, and running along the back of 
the head from the top downwards. The glands (/) 
are irregular-shaped, and are arranged like clusters 
of grapes. They are mter cellular^ and like a sac, 
lined with a single layer of cells so arranged that each 
cell presents a proportionately broad surface to the 
common cavity (Fig. 50, e), the material being ob- 
tained from the blood by the opposite ends next to 
the propria. 
Each sac is composed of the propria (z^), the 
