118 
GLAND STRUCTURE, 
worm - like enlargements of the glands it becomes 
thicker and more fully developed, and nucleated cells 
appear, which are capable of producing a secretion, 
whereas those towards the reservoir lose this power. 
Over the continuous cell layer there is also found a 
propria. This system is also intercellular^ and its 
structure is very similar in the queen and drone, the 
glands in these, however, being much smaller. The 
intima of the smaller reservoir in the drone, presents 
an irregular structure, owing to folds here and there, 
whilst in the queen it has only the spiral form of the 
other ducts, and the reservoir is even smaller than 
that of the drone, only appearing as a small swelling. 
The secretion of System III. is slightly alkaline, and 
almost neutral. 
System IV. 
This system has been described much later by 
Wolff (170) and Graber, as being an olfactory 
gland. Schiemenz and others, however, attribute 
to ii a digestive function. It is in connexion with 
the jaws (Fig. 51), there being one attached to each 
jaw. If the jaw is carefully removed, this gland will 
be seen as an irregular-shaped oval sac ( f ), from 
which in a fresh state a strong-smelling, intensely 
acid liquid can be pressed out. The sac is connected 
with the jaw by a short curved tube (//), forming the 
intima. This gland is intracellular in type, and 
similar to System L, the canaliculi in connexion with 
the cells having each a separate opening in the jaw 
at h. Although in places the cells are very close 
