3°8 
cells of doubtful origin, containing a large number of 
yellowish or black granules of large size. 
A peculiar phenomenon takes place in the wall 
of the sac as digestion proceeds; the inner layer 
escapes through the meshes of the outer in the form 
of a number of herniae, so that the whole gut appears 
as if studded with cysts ; a condition very marked in 
OrnithodoruSy but not to the same extent in Eurhipi- 
cephalus. 
Salivary Glands .—By displacing to one side the 
whole of^the diverticula, make out the large salivary 
gland of each side lying over the bases of the first and 
second legs (Fig. ioi). 
Lifting up the salivary gland by its posterior end, 
trace forward the salivary duct till it enters the 
chitinous ring of the pharynx. 
Examine in the fresh condition and ascertain 
that— 
(1) The glands are composed of immense num¬ 
bers of globular acini opening into short lateral ducts, 
which in turn open into a central large duct (Fig. 102). 
(2) Each acinus consists of several large cells, 
which exhibit different appearances at different stages 
and under different conditions of preparation. Note 
the globules of secretion packing these cells when 
mature. 
(3) In sections note a large clear cell at the point 
of entrance of the duct, and the different stages in the 
formation of the large secretory granules. 
Coxal Glands .—Lying partly under the salivary 
gland and partly internal to this structure observe a 
large flask-shaped organ, the coxal gland, conspicuous 
from the number of tracheae which supply it (Fig. 101). 
Cephalic Glands .—By displacing the diverticula 
from the extreme anterior portion of the body make 
