DIGESTIVE TRACT OF THE CAT. 



25 



which must have obstructed its path. At this stage of 

 development, the duodenum and its mesentery are resting 

 upon the caudate lobe of the liver. This lobe is wedge- 

 shaped, it is thicker externally than it is internally, con- 

 sequently the duodenum and its mesentery rest upon an 

 inclined plane which slopes to the left. The caecum in its 

 growth is obliged to ascend this inclined plane, and when it 

 reaches the top it encounters the edge of the caudate, as well 

 as at times the edge of the right central lobe of the liver, 

 which obstacles obstruct its further growth to the right. 

 The liver prevents its growth either cephalad or ventrad, and 

 besides this, the coils of the jejunum and ileum lie ventrad 

 from it. For these reasons, the caecum is forced to grow 

 caudad, parallel and to the left of the second portion of the 

 duodenum. It is in this manner that the ascending colon is 

 formed, and that the caecum attains its usual adult position, 

 to the right of the median line, and in close relation with the 

 duodenum. 



Intestinal Coils in the Embryo. 



Is there a constant arrangement of the coils of jejunum 

 and ileum either in the embryo or in the adult cat? 



The embryos were treated by the progressive alcohol 

 method, which sufficiently hardened their intestines and 

 mesenteries, so that they would remain in place while being 

 studied. 



Five embryos were first chosen, of 69, 71, 74, 75, and 80 

 millimetres in length. The coils of jejunum and ileum were 

 sketched, and at the same time a wire model was made, in 

 in order to determine if there was any general resemblance 

 in the position of the individual coils. It was surprising to 

 see that there was almost no resemblance whatever between 

 any two of the models. 



Feeling that this work was not sufficiently accurate, two 

 embryos were chosen from the same litter which resembled 

 each other in the period of development, in that the caecum 



