2 



the jejunum, and colon. This process continues until the 

 caecum lies in close apposition to the stomach. (Fig. 3.) 

 That portion of the colon which was formerly contained in 

 the cavity of the cord now lies within the abdominal coelom, 

 together with (approximately) a corresponding length of the 

 jejunum. 



The entrance of the caudal end of the digestive tract now 

 ceases, but the jejunum continues to enter the abdominal 

 coelom, until finally all that remains in the cavity of the cord 

 is a loop of ileum situated a few centimetres from the caecum, 

 and this is the last portion of the intestine to enter the abdom- 

 inal cavity proper. 



In my former article no explanation whatever could be 

 offered regarding the mode of entrance of the intestines, 

 nor any reason given for their definite order of entrance. 

 These two subjects form the chief topics of the following 

 observations. 



All the drawings were made with the aid of a camera lucida 

 from sections of cat embryos, and Figs. 1,2, 3, 4, and 5 were 

 drawn on the same scale. 



Fig. I is a sagittal section of an embryo 15^ millimetres. 

 An examination of such a section demonstrates perfectly how 

 completely, at this stage, the entire abdominal cavity is filled 

 by the liver, stomach, vessels, and colon, while most of the 

 small intestines and caecum are seen in the cavity of the um- 

 bilical cord. It shows also the great size of this cavity as 

 compared with the abdominal coelom. 



Fig. 2 represents a sagittal section of an embryo 24 mil- 

 limetres. The stage of development is more advanced than 

 in the last figure. The colon, the caecum, and a few coils of 

 jejunum may be said to have entered the abdominal coelom, 

 but the caecum has not as yet reached its characteristic posi- 

 tion (and one which it will occupy for some time to come) 

 in close proximity to the stomach. 



Fig. 3 is a sagittal section of an embryo 34I millimetres. 

 It represents a still more advanced stage of intestinal devel- 

 opment than either of the previous sections. The caecal ex- 

 tremity of the colon and caecum lie close to the stomach, the 



