470 
DE. HEEBEET WATNEY ON THE MINUTE 
tubes, and he also described the changes occurring in digestion. This paper will be 
referred to again. 
Loven (96) discovered lymph- vessels in the mucosa of the stomach extending into 
the plicse villosee. 
Rabe (97) noticed that, in the horse, the glands are of uneven length, and that this 
gives the mucosa a somewhat wavy surface. . 
The. general structure of the Mucous Membrane. 
If we harden the pyloric end of the stomach of a dog in chromic acid and examine : 
the surface with the naked eye, the mucosa, with the exception of a few large folds, 
presents a somewhat smooth surface. On examining this apparently smooth surface 
more carefully with the aid of a simple lens, we shall find that it is formed of a number 
of minute elevations and depressions. The principal elevations are parallel to the 
transverse axis of the stomach ; but they communicate by short branches running in 
the longitudinal direction, and thus they form a network of irregularly shaped meshes*. 
On making a longitudinal vertical section of the pylorus, these elevations are seen to 
be rounded, and give the mucous surface a wavy aspect. 
We notice, in the section, that the upper part of the stomach-tubes which open on 
the summit of these elevations is straight, and that the plicae villosee between the tubes 
are straight and long ; whereas the tubes which open into the depressions are shorter 
and wider, and their sides are folded (see fig. 26, Plate 42, where we find alternations of 
long straight tubes and of short tubes) ; and these appearances are very like those which 
Ebstein (95) has given in his fig. iv. and fig. iii. as representations of the stomach of a 
dog in stages of sponge feeding and of vegetable feeding respectively. 
These wave-like elevations of the mucous membrane of the stomach with the accom- 
panying differences in the length of the tubes are seen in dogs killed in all stages of 
digestion and hunger, and they are therefore to be considered a constant feature of the 
dog’s stomach. 
This feature is, however, not always well marked, if the stomach has been hardened 
in alcohol ; and it was completely absent in the stomach (hardened in alcohol) of a dog 
which had been fed on sponge after the manner of Spallanzani and Ebstein (95). 
It has been found that, as a rule, the mucosa is more contracted in digestion than in 
hunger ; this is also true of the plicae villosee, which are more expanded in sections made 
from the hardened stomach of an animal killed while fasting, than in sections made 
from an animal killed during digestion. 
The wave-like elevations of the surface of the pyloric end of the stomach are well 
marked in those animals which have very compound glands and much convoluted 
gland-tubes, as in the dog and horse. In the monkey, rabbit, and hedgehog these 
foldings of the surface are much less marked. In the rat the tubes are of even length, 
and the surface of the stomach is quite smooth. 
* Koilixee (44) has described a network of folds on the surface of tbe pylorus. 
