DEVELOPMENT OF THE LARGE INTESTINE 



189 



1 First injected with a mixture of phenol, alcohol, glycerine, and formalin 



2 Premature birth at seven (?) months. Lived thirty minutes 



3 Normal fetus at birth 



* Premature at seven months. Lived two weeks 



THE LARGE INTESTINE 



Early development 



In an embryo of 7.5 mm. the large intestine, like the oeso- 

 phagus, stomach, and small intestine of the same embryo, is a 

 simple tube of epithelium surrounded by mesenchyma. It is 

 continuous, without demarction, with the small intestine above, 

 and with the urogenital sinus below. Its cephahc end is indis- 

 tinctly indicated by a slight swelling, which is regarded by Lewis 

 ('11) as the beginning of the vermiform process. This sweUing, 

 which I will designate by the term 'colic ampulla' (ampulla 

 coli), is spindle-shaped and has a diameter (measured from side 

 to side in its widest place) of 0.07 mm. Below the swelling the 

 tube becomes markedly narrower. In its narrowest portion it 



