152 The Cardiac Glands of Mammals 
what advantage from the mere standpoint of the storage function a 
chambered stomach possesses over one in which this purpose is sub- 
served by a mere increase in size of the stomach. On this basis alone, 
it is difficult to understand the occurrence of a highly specialized 
chambered stomach in forms like Cricetus in which there are supple- 
mentary storage chambers in the form of capacious cheek pouches. It 
is possible, on the other hand, that the division of the stomach into two 
or more successive chambers has been an indirect effect of the increase 
in bulk of the food and its altered consistence and has been in reality 
a conservative effort on the part of the organism designed to check the 
further advance of the degenerative process in the mucous membrane. 
The evidence seems to indicate that the natural sequence of changes 
in the stomachs of herbivorous mammals and of certain other forms 
which subsist on a peculiar form of food, results in the suppression of 
the gastric glands beginning at the cesophageal orifice and gradually 
proceeding from left to right, involving more and more of the mucous 
membrane. Ultimately, if no conservative process intervenes, this 
would result in the complete suppression of the gastric glands, as has 
occurred in Echidna and Ornithorhynchus. 
The subdivision of the stomach by constriction into two or more 
chambers might be interpreted as such a conservative effort, the object 
of which is to check the advance of the degenerative process and so 
provide sufficient storage capacity to meet the needs of the animal with 
the minimum reduction of digestive potential. If it is true that the 
disappearance of the glands is due to the mechanical action of a food 
mass of unusual consistence, it is easy to understand how such a con- 
striction would be of use to the animal by confining the food to the first 
chamber until it had undergone such a change in consistence from 
maceration and the action of salivary and bacterial enzymes that it was 
no longer a source of danger to the mucous membrane. If the con- 
striction rapidly reached such a degree that food could only pass over 
into the second chamber after a considerable degree of softening had 
been reached, it would prove an effective barrier to the advance of the 
degenerative process. This appears to have been the case in the 
Tragulide. In many cases, however, the constriction has been insuffi- 
cient to check completely the degenerative process and merely retards 
it, as in the stomachs of Arvicola, Fiber, ete. An interesting example 
of this condition is afforded by Camelus and Auchenia in which not- 
withstanding the constriction, the degenerative process has invaded the 
distal segment of the stomach and converted the glands of a consider- 
able portion into cardiac glands. This doubtless represents, as Boas, go, 
