1888-89.] Woodhead and Gray on Stomach of Narwhal. 805 
respects. The glandular epithelium is, in both, entirely of the prin- 
cipal or pyloric variety, and the gland tubes are alike in other 
respects. The only valve-like structure with a sphincter muscle is 
met with at the distal end of the fourth compartment, and from this 
we conclude that at this point we have the termination of the true 
gastric function. From this description it is evident that, as Tyson 
and others assert, the first true digestive cavity^corresponds in every 
way to the cardiac end of the stomach of the carnivora and man ; 
whilst the following portions, with the exception, perhaps, of what 
we have called the econd true digestive cavity, must be looked 
upon as essentially pyloric in structure, and probably also in 
function.* 
* 
The Duodenum. 
The arrangement of the glandular tissue in the duodenum does not 
resemble any form we have seen described, except that met with in the 
intermediate glands between the true pyloric glands and Brunner’s 
glands in other animals. They form part of the mucosa proper, 
but between them are seen well-developed bands of muscular 
and lymphoid tissue apparently prolonged upwards, so that they 
come to be embedded in a kind of submucous tissue. The ducts 
are comparatively short, and are surrounded in their whole length 
by bands of non-striped muscular fibre. In addition to this set of 
bands of muscle, a well-developed layer of muscular fibre was 
observed parallel to the surface, and at the level of and sur- 
rounding the orifices of the ducts of these glands. It will at once 
suggest itself that the fibres running parallel to the gland tubes, 
during contraction, would drive out the secretion, but that those 
surrounding the mouths would constrict them regularly or inter- 
mittently, and so lead to a temporary storing up of the duodenal 
secretion. Such a suggestion is entirely hypothetical, except in so 
far as it is borne out by the arrangement of the bundles of non- 
striped muscular fibre, and by what we know of the process of 
digestion in other animals. 
It was unfortunate that the duodenum was cut off so short. We 
* Turner, loc. tit., would speak of the cardiac cavity as that immediately 
following the oesophageal paunch ; then there would he two intermediate 
cavities ; and lastly, a simple pyloric cavity. 
VOL. XVI. 26/2/90 
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