364 ELDON W. SANFORD 
Stomach and coeca. The stomach extends from the gizzard to 
the point of entrance of the Malphigian tubules. In its normal 
position it is curved, and bent so that its posterior end is almost 
directly below its anterior end. It is crowded in the abdominal 
cavity, and is small in proportion to the size of the animal and 
in proportion to the crop’s size. From the anterior end arise 
eight coeca, each of which is of about a third the diameter of the 
stomach and of about half the stomach’s length. The variation 
in size is very great, especially depending on whether the coeca 
are filled with food or not. Sometimes the coeca are as long as 
the stomach. The outer wall of the stomach is composed of a | 
loose meshwork of muscular fibers, among which tracheae 
ramify. The same can be said for the outer wall of the coeca. 
The assertion of Jordan that the fibers of the muscle meshes 
only pass under unspecialized cells seems to apply in the Ameri- 
ean cockroach. In this way much of the surface is left free of 
striated muscle, which would, if present, hinder the passage of 
food materials from the epithelial cells into the body cavity. 
The epithelial cells are in general long and narrow as seen in 
either transverse or longitudinal section, and are similar through- 
out the whole length of the stomach. As in most insects, the 
inner edge is set closely with fine filaments which serve to pro- 
tect the epithelial surface (fig. 21). At very frequent intervals 
groups of immature cells are seen between the true epithelial cells 
and the muscular layer. These cells are small and closely packed. 
In many places all intermediate stages between them and adult 
cells are seen, as shown in figure 21, so it seems certain that there 
is a continual replacement of the mature cells, which often die 
and are cast, as I shall later describe. The epithelium usually 
shows but few adult cells in a group, and these groups more or 
less widely separated by the intermediate cells which take their 
places later. The surface of the epithelium may be flat or undu- 
lating, but is often raised into small villi with U-shaped spaces 
between them, the so-called crypts of Frenzel. The ends of the 
villi may be smoothly rounded or bulged out considerably. 
The arrangement in villi allows a much greater surface for secre- 
tion and absorption. I agree with Biedermann that the crypts 
