4-4 Wisconsin Academy of Sciences, Arts and Letters . 
The histological change, at the place where the crop passes 
over into the gizzard, is abrupt. At this region the large, 
narrow folds of the crop gradually become flattened and finally 
form an almost unfolded chitinized epithelium, which con¬ 
tinues over into the unfolded chitinized epithelium of the giz¬ 
zard. In the former, the thin, hyaline chitinous layer with its 
numerous blunt projections passes over, in the gizzard, into a 
thick intima which has numerous long, backward-pointing bris¬ 
tles (Fig. 7, &). The cellular change between these two parts 
of the fore-intestine is more abrupt. The ovoid nuclei of the 
epithelial cells of the crop assume a direction parallel to the 
almost unfolded chitin; these cells are then replaced in the giz • 
zard by cubical cells with large spherical nuclei. 
The most striking feature in a longitudinal section of the 
gizzard is the thickness of the muscle layers and their attach¬ 
ments. Externally, some of the longitudinal muscles can be 
traced from the mid-intestine directly to the gizzard; others, 
however, like some of the longitudinal muscles of the crop, at¬ 
tach to the chitinous intima of the gizzard (Fig. 7, Zm. meZ). 
Numerous branches from these external longitudinal muscles, 
and sometimes an entire fiber, penetrate the circular and inner 
longitudinal layers (where the latter are present), spread out 
in a somewhat fan-shaped manner just before reaching the 
epithelial cells, and finally attach to the chitinous intima. 
This peculiar branching continues from the beginning of the 
mid-intestine as far as the external longitudinal muscles ex¬ 
tend anteriorly (Fig. 7, him). Some of the external longi¬ 
tudinal muscles attach to the chitinous intima near the be¬ 
ginning of the gizzard. The circular muscles just internal to 
these longitudinal ones are exceedingly thick; they attain their 
maximum thickness near the beginning of the “pedunculus” 
and disappear near the anterior end of the appendix. Follow¬ 
ing these circular layers within are the inner longitudinal mus¬ 
cles, which attach anteriorly to the chitin of the gizzard (Fig. 
7, Urn) ; posteriorly, some of these muscles attach to the chi¬ 
tinous layer at the anterior end of the “pedunculus,” while 
others can be traced to the posterior end of it. 
