14 Emil Goetsch. 
and complete cornification of the superficial layers of the epithelium 
to constitute a true stratum corneum composed of flattened cells 
wholly devoid of nuclei, and comprising over one-third of the total 
thickness of the epithelium. Below the stratum corneum in this 
type a true stratum granulosum is found consisting of two or more 
layers of cells, of elongated fusiform shape in section, containing 
numerous granules of eleidin staining blue in hemalum. The 
stratum germinativum is relatively thin as compared with that of 
the second type. This type of epithelium is found in the guinea pig 
(Fig. 5 B), rat, pocket gopher and porcupine. ‘The second type of 
epithelium (Fig. 6) also shows a considerable degree of cornification, 
but a true stratum corneum is not present, the superficial layers of 
flattened cells being nucleated and no stratum granulosum being 
found. In this epithelium the process of cornification appears to go on 
more gradually than in the first type and no sharp line can be drawn 
between the stratum corneum and the stratum germinativum. ‘The 
superficial half of the epithelium nevertheless consists of flattened 
cells with elongated nuclei and stains more strongly in eosin than 
the deeper layer. Comparing this epithelium with that of the dog 
it is apparent that the degree of cornification is much greater in 
the rodent and that the thickness of the epithelium considering the 
relative sizes of the animals is much greater. True papille of the 
lamina propria mucose are not present in the rodents examined. In 
Cavia, Arctomys, Sciurus, Tamias and Lepus, however, as described 
by Strahl (89), the lamina propria mucosz projects into the epithe- 
lium in the form of irregular ridges for the most part longitudinal 
in direction, and in Cavia and Tamias these have irregular summits 
which in places approximate the formation of papille. In Mus, 
Geomys, and Erethizon, there are neither ridges nor papille. 
The 1. muscularis mucose is present throughout the whole length 
of the cesophagus in all the rodents examined. It is particularly 
well developed in the squirrels, where it forms a continuous layer 
around the cesophagus. 
The tunica muscularis in the rodents consists of striated fibres 
throughout the greater extent of the esophagus. In Cavia, Geomys, 
Mus, Tamias, and Lepus the striated fibres are found to the cardiac 
