498 FREDERIC T. LEWIS 



gastric epithelium is seen to be slightly invaginated into the duo- 

 denal tube, as observed by Cunningham at birth. Toldt found 

 that the sulcus pyloricus could be seen externally in an embryo of 

 48 mm., and presumably it could have been found in this specimen 

 by dissection. 



The pars pylorica, even in the 44.3-mm. embryo, fails to show 

 distinct subdivision into antrum and vestibule. Muller, who 

 studied dissections of the embryonic stomach, states that in the 

 'first fetal period' the pyloric antrum is a direct continuation of 

 the pyloric vestibule, but that later, when the pars pylorica is 

 bent convexly upward, the general direction of the vestibule is 

 upward, and of the antrum, downward. In the earlier period the 

 antrum is characterized by "its cylindrical form and the great 

 development of its muscle-layer." In the still earlier stages under 

 discussion, neither distinction is applicable, for the entire pars 

 pylorica is cylindrical, and as shown in figure 11, its musculature 

 is thick. It is possible that the short and relatively smooth 

 terminal portion of the pars pylorica, which in figure 9 is seen to 

 be directed upward, represents the antrum; but this cannot be 

 affirmed without further investigation. 



In conclusion, the abnormal stomach shown in figure 7 may be 

 considered. It is of special interest since Gardiner (1907) has 

 described the stomach of a child of three months, which presents 

 a very similar condition. In the embryo there is a round nodule 

 of epithelial cells near the angular incisure. In sections (figure 

 12) this nodule appears as a compact ring of radiating cells 

 arranged about a lumen. Toward the gastric epithelium there 

 is one section in which this structure fails to appear, so that it is 

 apparently detached, but a short stem projects towards it from 

 the adjacent epithelium. Both the nodule and its stalk are inside 

 of the muscular coat. A comparable but larger structure was found 

 by Lewis and Thyng in the duodenal region of a 20-mm. pig 

 (figured in this Journal, vol. 7, p. 509). In that case, however, 

 the detached portion, which had become cystic, lay outside of the 

 tunica muscularis. That the nodule in the human embryo is an 

 accessory pancreas, is made certain by Gardiner's specimen, in 

 which a well developed gland with typical islands occurs in a 



