134 The Cardiac Glands of Mammals 
cells as indicated by their structure, and (3) the tardy assumption by 
the cells of the cardiac glands in the pig of the mucigenic function. 
THE PHYLOGENETIC SIGNIFICANCE OF THE CARDIAC GLANDS 
AND THE SO-CALLED GSOPHAGEAL SACS. 
Concerning the phylogenetic significance of the cardiac glands the 
various writers express themselves with considerable reserve and not 
always with clearness. Edelmann, 89, suggests two possibilities as fol- 
lows: ‘* Phylogenetisch kann die Cardiadriisenregion entweder als ein 
in die Bildung des Magens hineingezogener Abschnitt der Vorderdarm- 
driisen oder als ein modificierter Teil der Schleimhaut des Mitteldarms 
aufgefasst werden.” Between these two possibilities he does not at-. 
tempt to decide. He, however, regards the cardiac glands as physiolog- 
ically important structures. ‘“ Die physiologische Bedeutung der Car- 
diadriisenregion beruht in der Bildung einer Art Vorraum im Magen, 
welcher keine Saure dagegen Fermentquellen enthilt, und in dem die 
Verdauung der Starke vor sich gehen kann.” “Der von der Cardia- 
driisenregion gebildete Vorraum fiir die Starkeverdauung kann zum 
Teil ersetzt werden durch cesophageale Vormigen, so dafs die Cardia- 
driisenregion also auch mit diesen morphologisch in einem korrespon- 
dierenden Verhiltnis steht.” This last sentence would seem to imply 
the view that both cardiac gland and cesophageal sac have a common 
origin, but for the doubt expressed in the first sentence quoted as to the 
phylogenetic significance of the former. 
Oppel, 96, suggested that the conditions described by Schafer and 
Williams, 76, Cordier, go, and others, in the kangaroo, were primitive 
and that the simple glands or cardiac glands of these animals were of the 
same nature as the simple gastric gland of lower vertebrates. This sug- 
gestion, which, indeed, the author did not seriously advance, may be 
dismissed with but slight discussion. In the first place, the cardiac 
glands are not histologically similar to the fundus glands in the lower 
vertebrates, and in the second place, the more primitive marsupials, 
such, for example, as the opossum, resemble closely in the structure of 
their stomachs the simplest conditions found in the placental mammals. 
The universal occurrence of cardiac glands in Mammalia seems prob- 
able. It is true that their presence in the carnivorous Cetacea and in 
the ruminants was denied by Edelmann and in three of the suborders 
of Rodentia by Fleischmann. The latter author, however, did not 
recognize as cardiac glands the extremely narrow zone of mucous glands 
found around the cardiac orifice of the stomach in these forms, nor the 
narrow zone of similar glands found along the “ Grenzfalte” in the 
Myomorpha. 
