16 



DR. E. LONNBERG ON DIGESTIVE 



[Jan. 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 mm. thick, and protrude in the preserved 

 state, as circular valves 3 mm. or more, into the lumen of the 

 caecum ; and there is no doubt that in the living animal they are 

 capable of entirely shutting oS one portion of the cfecum from 

 the other, thits retaininsr the enclosed food during a suitable time 



Text-fig. 4. 



Caecum of Trichosurus mdpecula. Nat. size. 



for decomposition. The walls of the csecum 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 csecum is, at least from the third 

 sphincter and onwards, transversely plicated, the plicee 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 



