The stomach is simple, and there is no caecum to the intestine, although this is present in the opossums.
Caecum of moderate size.
With one exception, the intestine has a caecum, and the pouch is large and opens forwards.
Caecum very short and wide, with a vermiform appendage (see Wombat).
Caecum very long and dilated, with numerous folds.
Caecum present (except in Tarsipes), and usually large.
From this we pass to a stomach and a coil of intestine embedded in the lobes of a voluminous liver; a caecum of large size is given off near the commencement of the intestine.
Protonemertini, in which there are two layers of dermal muscles, external circular and internal longitudinal; the nervous system lies external to the circular muscles; the mouth lies behind the level of the brain; the proboscis has no stylet; there is no caecum to the intestine.
Heteronemertini, in which the dermal musculature is in three layers, an external longitudinal, a middle circular, an internal longitudinal; the nervous system lies between the first and second of these layers; the outer layer of longitudinal muscles is a new development; there is no intestinal caecum; no stylets on the proboscis and the mouth is behind the level of the brain.
It is at times sacculated, but its chief interest is that, as Lebedinsky 1 has shown, the tip of the caecum in embryonic life opens to the exterior as the blastopore.
The stomach is simple, the caecum large and capacious, the placenta diffused, and the teats inguinal.
In all known Pantopoda the size of the body is quite minute as compared with that of the limbs: the alimentary canal sends a long caecum into each leg (cf.
In some of the v, Caecum of stomach.
V, Caecum of stomach.
A pyloric caecum connected with the stomach is commonly found, containing a tough flexible cylinder of transparent cartilaginous appearance, called the " crystalline style " (Mactra).
The radula consists of a chitinous band bearing teeth, secreted by a ventral caecum of the pharnyx and moved by an apparatus of cartilage and muscles.
The teeth are secreted by a small number of cells at the closed end of the caecum, the basal membrane by a transverse row of cells in front of these.
Beneath the anterior parts of the radula where it emerges from the caecum are a pair of cartilages, and attached to these a number of special muscles by which the radula is moved backwards and forwards to act as a rasp. The secretion of the radula at the closed end of the caecum is continuous, so that it is constantly growing forward as fast as its exposed anterior portion is worn away by use, just as a fingernail is pushed forward by constant growth at its posterior end, and is worn away or has to be cut short from time to time at its outer end.
All rodents, with the sole exception of the dormice, have a caecum, often of great length and sacculated,, as in hares, the water-rat and porcupines; and the long colon in some, as the hamster and water-rat, is spirally twisted upon itself near the commencement.
In the soft parts the caecum is very large, the penis is armed with a pair of barbed horny claspers and the scrotum is spiny.
The intestinal canal is long, and has, in addition to the ordinary short, but capacious and sacculated caecum at the commencement of the colon, lower down, a pair of large, conical, pointed caeca.
No food passes into the hepatic caecum, which has been definitely shown on embryological and physiological grounds to be the simplest persistent form of the vertebrate liver.
In general structure they all closely resemble human beings, as in the absence of tails; in their semi-erect position (resting on finger-tips or knuckles); in the shape of vertebral column, sternum and pelvis; in the adaptation of the arms for turning the palm uppermost at will; in the possession of a long vermiform appendix to the short caecum of the intestine; in the size of the cerebral hemispheres and the complexity of their convolutions.
Alimentary canal; in man and mammals divided into the smaller intestine, from the pylorus to the iliocaecal valve, and the larger, reaching from the caecum and colon to the end of the rectum.
The alimentary canal is long, and the caecum well developed.
The stomach is small; into it open a small pyloric caecum and the ducts of the liver, paired in Dentaliidae, one on the left only in Siphonodentalium.
- Diagrammatic the canal is the frequent presence of a blind Plan of the general pouch, " caecum," situated at the junction arrangement of the of the large and the small intestine.
It is only in herbivorous mammals that the caecum is developed to this great extent, and among these there is a complementary relationship between the size and complexity of the organ and that of the stomach.
Where the latter is simple the caecum is generally the largest, and vice versa.
(1905) of the Transactions of the Zoological Society of London, Dr P. Chalmers Mitchell has identified the paired caeca, or blind appendages, of the intestine of birds with the usually single caecum of mammals.
Among mammals, o, oesophagus; st, stomach; p, pylorus; ss, small intestine breviated); c, caecum; ll, large intestine colon, ending in r, the rectum.
(ab or the horse and the dog may be cited as instances where the single caecum is of large size, this being especially the case of the former, where it is of enormous dimensions; in human beings, on the other hand, the caecum is rudimentary, and best known in connexion with " appendicitis."
In mammals both caecum and colon are often sacculated, a disposition caused by the arrangement of the longitudinal bands of muscular tissue in their walls; but the small intestine is always smooth and simple-walled externally, though its lining membrane often exhibits contrivances for increasing the absorbing surface without adding to the general bulk of the organ, such as the numerous small tags, or " villi," by which it is everywhere beset, and the more obvious transverse, longitudinal, or reticulating folds projecting into the interior, met with in many animals, of which the " valvulae conniventes " of man form well-known examples.