362 ELDON W. SANFORD 
as two or three cells might combine to one ring cell. In the 
species I have studied this appears not to be the case. I have 
never found any such appearances except in preparations which 
were fixed in absolute alcohol, and even then the appearances 
were not distinct, and probably represented artifacts due to too 
rapid dehydration. 
Gizzard. The gizzard consists of two distinct parts, an anterior 
and a posterior. Its shape is in general that of a cone whose 
blunt end is anterior and adjoins the crop and whose pointed 
end extends into the stomach. Its altitude about equals the 
diameter of the base. The hinder; protruding part is of about 
the same length as the anterior part. The two parts are entirely 
different histologically. In the anterior part the chitin forms 
six heavy teeth; the chitin has no distinguishable structure for 
the most part, but may be shown by staining with erythrosin 
to consist of three homogeneous layers, an outer and an inner 
layer which take no stain and a median layer between them 
which stains bright red. 
The six thick teeth fill most of the cavity of the anterior part. 
They are large projections, triangular in cross section and roughly 
rectangular in longitudinal section, which nearly fill the space 
within, leaving only a narrow lumen in the middle and small 
spaces between their sides (fig. 8). The outlines of the teeth 
are not quite triangular, but often have swellings or concavities 
on the sides and somewhat flattened points. Usually a swelling 
of one tooth lies opposite a cavity on the adjacent tooth, and 
flattened and pointed ends do not sharply oppose each other. 
Ramme has found that in cockroaches the six teeth fit tightly 
and perfectly and are so well held together by the thick circular 
muscles that a tight fastening may be made. 
Under the chitinous intima lies a single layer of long cylindrical 
epithelial cells, and below them a mass of connective tissue, 
through which run many tracheal tubes. Just under the epi- 
thelial cells these tubes end in tracheal end cells, whose proc- 
esses run up between the cells above. Outside of the con- 
nective-tissue layer is a broad layer of circular striated muscles. 
