360 ELDON W. SANFORD 
tightly over any food within. The other layer consists of lon- 
gitudinal muscles. The muscles form a loose network, and 
through the meshes the general body cavity connects with spaces 
under the epithelial cells. These spaces are under folds in the 
epithelial layer in the usual state, but are nearly or quite oblit- 
erated when the crop is distended with food. -In these folds 
are found muscle fibers and processes; which run from the mus- 
cular layer to the epithelial and chitinous layers, and may be 
considered as radial muscles, as shown in figure 2.. Wandering 
blood cells and tracheal branches are also found in these spaces 
(fig. 2). The latter extend on one side to larger tracheal branches 
and on the inner side to tracheal end cells. 
The epithelial cells have the shape of hexagonal prisms twice 
to four times as high as broad. The nuclei are situated near the 
bases of the cells; that is, toward the body cavity, as shown in 
figures 2, 5, 17. The cytoplasm of the nuclear region usually 
stains more deeply than the cytoplasm of the other end of the 
cell, and is apparently more specialized. Between the cells and 
the lumen of the crop is the rather thin chitinous intima. 
Petrunkevitch has demonstrated that this intima is porous, and 
I have verified his work, using his methods. Some earlier 
workers used this porosity to account for the passage of fat 
globules into the cells from the lumen, but it is now known that 
fats cannot be absorbed as such, but must be split to fatty acid 
and glycerol, both of which, being soluble, may be absorbed 
into the cells. 
The muscular layer may be separated to a greater or less extent 
from the epithelial layer by teasing with needles under a bin- 
ocular microscope. This applies for the oriental cockroach, and 
not for the American cockroach. Flat preparations of the 
epithelium may be made by holding a piece of the crop’s wall 
tightly down and flattening out folds under a coverglass, then 
running in Flemming’s fluid, or absolute alcohol, as recom- 
mended by Petrunkevitch. A much better method of getting 
flat preparations consists in feeding an animal until its crop is 
distended and therefore all the folds of the surface are smoothed; 
the crop is then removed without puncturing and preserved in 
