136 The Cardiae Glands of Mammals 
of the stomach of ruminants entitles his opinion to some weight, ex- 
presses himself thus: ‘On est done en présence d’une cavité a son 
maximum de differenciation””—* Je me refuse absolument a croire, par 
example, a Vorigine cesophagienne du rumen.” 
The alternative hypothesis 
A that the cardiac sacs have 
been derived by a_ gradual 
change in the cardiac portions 
of the stomach by reason of 
which the glands have disap- 
peared and the epithelium 
has changed in character, sug- 
gests an examination of the 
stages, if stages there be, and 
of the factors that have been 
operative, in the production 
of this extraordinary transfor- 
mation. 
Before proceeding with the 
discussion of this matter, a 
brief survey will be made of 
the relations and extents of 
the various portions of the 
stomach in a number of rep- 
resentative species of several 
orders of Mammalha. 
In the Monotremata the 
stomach is lned throughout 
by stratified squamous epithe- 
aoe lium and is quite devoid of 
Frias. 10-16. Diagrams to illustrate the regions 7 
occupied in different stomachs by the various glands although a well-devel- 
kinds of glands. 4 . 
Fig. 10. Stomachsof: A, Didelphys; B, Dorcop- oped group of Brunner’s 
sis; C, Macropus; the two latter after Schiifer and 2 F 
Williams. glands is found at the pyloric 
Abbreviations: Ca=cardiac glands; F—fundus oritice 
glands; P=pyloric glands; Oe=portion of stomach ; 
without glands and lined by a stratified epithelium. Amone the ma rsupials two 
2 s 
types of stomach are met with. In the opossums (Fig. 10, A) Dasyures, 
Bandicoots and Phalangers the stomach is simple, resembling closely 
in shape and in the arrangement of its parts those of the insectivorous 
and carnivorous placentals. A large fundus-gland zone occupies the 
greater portion of the mucous surface, the rest being occupied by the 
pyloric glands. The cardiac gland zone is either altogether absent 
