ABDOMINAL VISCERA OF THE HORSE. 677 
direction, but which are not traceable on to the oesophagus, as 
they seem to pass round each side of the cardia, and blend with 
the circular fibres on the lesser curvature. 
The middle layer consists of annular fibres, which, though 
scanty as they encircle the extreme left end of the stomach, 
increase in bulk towards the middle part of the organ, and are 
especially developed at the lesser curvature. They again 
decrease over the antrum pylori, but are ultimately greatly 
developed for the formation of a powerful sphincter at the 
pylorus. 
The internal or oblique fibres of the stomach have somewhat 
the same arrangement as the deep layer of fibres of the oeso- 
phagus, although not perfectly identical, as they are arranged 
like hoops placed one within the other ; but while in the former 
the one set enters the other without intersection, in the latter 
there is a partial decussation by separate bundles. Thus, in 
reality, the oblique fibres of the stomach are constituted of two 
layers, the one proceeding from the left end of the stomach on 
to the right, which pass internally to the next layer : this one 
proceeds from the right of the cardia on to the fundus. Owing 
to the scantiness of circular fibres at the base of each cul-de-sac, 
the fibres are here in contact with the superficial longitudinal 
ones. The oblique fibres are best studied by dissecting from 
within, and, after removing these, the circular fibres come into 
view with greater ease than by attempting to expose them from 
without. 
The third coat of the stomach consists merely of the cellular 
tissue existing between the muscular and mucous coats, as well 
as connecting the former to the outer serous tunic, in which 
case it is more abundant and firm nearest the curvatures. There 
it is situated between the muscular and mucous coats : it was 
named by the ancients, on account of its white aspect, the 
Tunica Nervosa. It is loose in some parts and firm in others; 
not only serving to connect parts together, but also to form a 
medium in which vessels ramify for the supply of the organ. 
The internal or mucous coat of the stomach differs in the 
cardiac from the pyloric end, as in the former it is but a 
mere continuation of the unmodified mucous lining of the oeso- 
phagus, being characteristic for its scantiness in glands and but 
limited supply of blood. The most marked feature it possesses 
is that of being covered by a cuticular layer of extreme thick- 
ness, easily separable from the basement structure beneath 
after slight maceration or boiling. The cardiac portion of the 
gastric mucous lining is, in a healthy stomach, of a dirty white, 
bedewed by more or less mucus, and thrown into folds which 
have a radiated arrangement at the cardiac orifice, whilst at the 
