38 INTESTINE AND DIET OF REPTILES. 



very difficult to decide in favour of either of these views. 

 The fact that a more or less developed coecal diverticle is 

 found in so many lizards of different families and also in 

 some other reptiles, snakes as well as tortoises, speaks for 

 the theory that such an organ might have been inherited 

 from the ancestors of the reptiles. In many batrachians^ I 

 have also seen (in opposition to the usual statements in ma- 

 nuals and textbooks) that the small intestine opens excentri- 

 cally into the large one, so that a more or less pronounced 

 one-sided dilatation is formed which may sometimes take the 

 shape of a coecal diverticle. This speaks also for the great 

 phylogenetic age of a crecal dilatation at the anterior end of 

 the large intestine in the vertebrate series. Bnt it is at the 

 same time very easy to nnderstand how such a one could 

 originate. As soon as a distinction between the small and 

 the large intestine had been fully developed with sphincter 

 and valve, the condition was fulfilled which could lead to 

 the development of a coecum. When the food-material was 

 pressed from the small intestine into the large one, the lat- 

 ter must be distended and as the large intestine lay closely 

 pressed to the body-wall of the right side this distention and 

 dilatation must more easily take place towards the median 

 or left side where the pressure was less efFective, or even 

 became diminished when the small intestine emptied itself 

 into the large one. It is not difficult to understand that 

 this could at the same time cause a displacement of the ter- 

 minal opening of the small intestine towards the right side 

 as a result of the uneven dilatation towards the left. In the 

 majority of cases, as can be seen from the descriptions above, 

 the opening of the small intestine lies to the right and the 

 coecal säck to the left, that is when the conditions have not 

 been complicated. ^ When this is so the explanation just 



^ Only to mention a few forms: Snlamandra, Molge poiretii, torosa, 

 a. o., Amhlystoma opacum, Spelerpes lovgicanda etc. have a quite conspl- 

 cuous excentricity; tLe same is the case with Xenopxis millleri, Bnfo lenti- 

 ginosus, a. o. Cornnfer corrngahis, Råna tigrina, jerboa a. o. In Hyla 

 versicolor, Borhoroccetes tceniatus and some others it can even be spöken 

 about a coecum although it is short and wide. In all these cases the large 

 intestine ought to be filled to show plainly its shape. 



- In addition to the hydrostatic pressure caused by the squeezing of the 

 contents of the small intestine into the large one together with the greater 

 or smaller counteracting influence from the body-wall and the to the large 

 intestine adjoining organs there may also be other fa<'tors which have con- 

 tributed to the excentricitv of the large intestine. It must be remembered 



