PHYSIOLOGY OF DIGESTION IN BLATTIDAE 385 
The secretion, as Deegener and Jordan describe it, appears in 
little sacs which are formed at the ends of the cells and free 
themselves into the cavity. Holtz describes the pouring out of 
granules of secretion in Nematus. Steudel injected Congo red 
solution into the body cavity, and later found it appearing in 
more concentrated form in the extruded secretion sacs. Schro- 
der holds that the sacs or lobes are not actual secretion, but 
that the secretion comes from a broader region of the cell. The 
projections may be for the secretion’s dispersal, he says, and may 
form a broader surface for it. 
VanGehuchten and Deegener have figured the release of 
spheres of secretion, and describe a cycle through which the 
secreting cells pass in three stages: 1) the formation of the sphere 
and its granular contents; 2) the completion of the sphere and 
its release; 3) the cell rests, meanwhile resembling a typical 
epithelial cell and probably being adapted to absorb soluble 
food substances. The process is described as continually going 
on, so that secretion is always ready for food when it arrives. 
The cells cannot form secretion spheres indefinitely long, but 
finally weaken and are cast loose with their last secretion sac. 
Several other authors have described the discharge of the oldest 
cells. 
The appearances on my slides agree mostly with the observa- 
tions of Deegener. The sacs at the ends of the cells and with 
their granular content are common, and many discharged sacs 
are seen in the lumen. Many regions of the epithelium show 
no signs of sac formation; these are in the resting stage. A 
density of the protoplasm near the ends of many cells indicates 
evidently a very early stage in the formation of a secretion of 
a secretion sac. All cells are able to secrete, provided they 
reach the surface, and the coecal cells show exactly similar sacs 
to those of the stomach, as we should expect from the similar 
histological structure. Both absorptive and non-absorptive 
cells are able to secrete. The absorbing cells are more active 
in secretion, perhaps because they are more mature. Every 
cell of a group of actively absorbing cells will very often show 
a large secretion sac. The presence of secretion is absolutely 
