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Show 16 DR. E. LONNBERG ON DIGESTIVE [J: an. 14, distance from the first. The third, which is almost the strongest lies still 4 cm. nearer the blind end. The fourth, which is about equal to the third in strength, is situated at a distance of about 8 cm. from the tip of the distal end. These two last-mentioned sphincters are 3| to 4 m m . thick, and protrude in the preserved state, as circular valves 3 m m . or more, into the lumen of the caecum; and there is no doubt that in the living animal they are capable of entirely shutting off one portion of the caecum from the other, thus retaining the enclosed food during a suitable time Text-fig. 4. Caecum of Trichosurus vulpecula. Nat. size. for decomposition. The walls of the caecum increase considerably in thickness towards its blind end ; and it is evident that this increase includes the muscular coat as well as, and that especially the glandular layer. This is the reason why the sphincters also must have an increased size and strength towards the blind end The mucous membrane of the caecum is, at least from the third sphincter and onwards, transversely plicated, the plicae becoming more prominent towards the blind end. They do not extend however, as simple plicae all round the caecum, but the ridges' anastomose now and then so that they form a network with |
