18 INTESTINE AND DIET OF REPTILES. 



extension measiiring abont 2 em. in a radial direction. Aboiit 

 twelve mm, from this last oue there is still a third also se- 

 milunar (Fig. 5, III) in shape and somewhat smaller, not 

 qnite reaching a depth of 2 era. Not quite 1 em. fnrther 

 down is still another semilunar valve (Fig. 5, IV) smaller 

 tlian the foregoing and with a maximum depth of about l^/a 

 cm. and iinally seven millimetres from that a fonrth small 

 semilunar valve (Fig. 5, V) with a maximum height of only 

 5 mm. All these (1 circular and 4 semilunar) valves or septa 

 are sitiiated within the widely expanded portion of the colon 

 as is mentioned above. The broadest part of the circular 

 valve as well as that of the others is situated on the mesen- 

 teric side of the colon and the latter are wholly confined to 

 that side leaving a more or less broad portion of the oppo- 

 site side free. At the above described sharp bend of the co- 

 lon there is no other mechanical hinder than the bend itself 

 which is so sndden that the adjoining walls of the intestine 

 at the same are in contact for a length about 2 em. and have 

 coalesced, thus in a certain sense forming a kind of valve 

 protruding into the lumen. The limit between the colon and 

 the rectum is well conspicuous through the different struc- 

 ture of the walls, those of the former beiug thin and those 

 of the latter thick and muscular. 



Thanks to these valves or septa of the colon the food- 

 material ean be retained a considerable length of time and 

 be subjected to the influence of the reagents of this part of 

 the intestine till it has been sufficiently deeomposed to be 

 digested. The contents of the colon was of vegetable origin. 

 In the upper part between the valves large pieces of the 

 skeletal network of leaves with the vessels ean be distin- 

 guished, but the softer parenchymatous tissue has wholly 

 disappeared. Further down near the rectum even the vessels 

 seem to be in some places more or less destroyed so that 

 the spiral threads lie loose, but partly they still form a cohe- 

 rent network. Large, completely hyaline flaps show them- 

 selves under the microscope to be only the cutieula of the 

 epiderm of leaves. The other parts of the epidermic cellules 

 have completely disappeared. The digestion seems conse- 

 quently to be rather thorough. 



The ccpcum and colic valves of Iguana have long been 

 known and even described by several authors. The best 



