R. R. Bensley : 147 
a point where the bulk of the changes are degenerate, a new interme- 
diate zone of cardiac glands can only be produced by the transforma- 
tion in situ of fundus glands. 
2. In some mammals, Bradypus, Camelus, ete., cardiac glands have 
been retained in the mucous membrane of certain saccular diverticula 
of the stomach which on account of their shape have not experienced 
the full effect of the mechanical action of the food. 
3. Comparing the stomachs of Macropus and Dorcopsis a most re- 
markable resemblance is observed in the external form and in the rela- 
tive extents of the pyloric gland and fundus gland zones respectively. 
In Dorcopsis, however, the cardiac zone region is much smaller than in 
Macropus and the cesophageal portion much larger. It is evident that 
this condition has been reached by the suppression of the anterior car- 
diae glands and their replacement by a stratified epithelium. A similar 
comparison may be drawn between Sus and Dicotyles. 
4. In a retrogressive process affecting such a structure as the gastric 
gland composed of several kinds of elements, it is reasonable to suppose 
that the various elements would disappear in the order of their speciali- 
zation, that is, by inference, in the inverse order of their power of inde- 
pendent reproduction. Chief cells and parietal cells rarely divide and it 
is difficult to decide as to their degree of relative specialization. The 
whole question of the nature of the parietal cells has been reopened by 
Schaffer’s discovery, recently confirmed by Hewlett, o1, of their occur- 
rence in the glands of the mucous membrane (obere cardialdriise) of the 
upper portion of the human esophagus. It is possible that we shall 
be forced presently to admit that we know nothing of their nature or 
function and include them in a common category with those other little 
understood elements, the crescent cells of mucous glands. Both chiet 
and parietal cells are clearly more highly specialized than the mucous 
neck cells for the latter sometimes undergo division. In the histo- 
logical part of the paper attention has been directed to a number of facts 
which point to the conclusion that the cardiac glands have been so 
derived from the:fundus glands by the disappearance first of the chief 
cells and second of the parietal cells. 
An analysis of the causes that have been operative in producing these 
changes is beset with unusual difficulties. In his discussion of the re- 
sults of the research of his pupil, Toepfer, on the stomach of Rodentia, 
Fleischmann, gi, utters a warning against the too hasty conclusion that 
the specialization which has taken place in such stomachs as those of 
the Ruminants and Myomorpha is due tc an herbivorous diet. He 
points out that in three out of the four main subdivisions of the Roden- 
