490 



been unable to detect any constant variation according to age. The 

 only variation noticeable according to age is that in younger foetuses, 

 before the adhesion of the duodenum and head of pancreas to the 

 dorsal body wall, the relation of the pancreas to the vertebral column 

 is not so intimate and relatively less extensive in the vertical direction. 

 In measuring the level of the pancreas with respect to the vertebral 

 column, I take as the longitudinal axis the general direction of the 

 vertebral column in the corresponding region. On account of 

 the extreme flexure in the cervical region, it is impossible to determine 

 satisfactorily a longitudinal axis for the body as a whole, correspond- 

 ing to the vertebral axis after birth. 



The most characteristic feature in the topography of the head of 

 the foetal pancreas is its relation to the liver. Toldt (13) discovered 

 that in a human embryo of six weeks the entire duodenum (excepting 

 the duodeno-jejunal angle) and the head of the pancreas are still en- 

 closed in a free mesoduodenum. He also observed that they are se- 

 parated from the posterior body wall by a portion of the liver (later 

 identified as the processus caudatus) which gradually retracts, 

 allowing the duodenum, together with the corresponding portions of 

 the head of the pancreas, to touch and adhere to the dorsal body 

 wall in the following order: At twelve weeks, the pars horizontalis in- 

 ferior becomes adherent ; at sixteen weeks, the lower half of the pars 

 descendens; at twenty-four weeks, all of the duodenum except the 

 pars superior (i. e., the adult condition is attained). According ta 

 Toldt, therefore, the head of the pancreas should be excluded from 

 direct relation with the liver at the beginning of the second half of 

 foetal life. I find that there is a great variation in this respect, 

 however, and that the lower part of the caudate process may remain 

 in relation with the posterior surface of the head of the pancreas to 

 a slight extent even in the new-born (Fig. 5). 



The area of the processus caudatus in contact with the pancreas, 

 as found in a foetus of the sixth month, is "represented in Fig. 1. The 

 caudate process is long and wedge-shaped, and extends downward inta 

 a peritoneal fossa of corresponding shape, which therefore may be 

 designated as the caudate fossa or the recessus caudatus. As 

 seen in Fig. 5, in sagittal section, this peritoneal fossa is bounded 

 anteriorly by the posterior surface of the head of the pancreas and 

 by the ligamentum hepato-duodenale, i>osteriorly by the right crus of 

 the diaphragm. This section passes through the inner part of the 

 fossa, however. Externally, as may be seen in Figs. 2, 3, 4, the re- 

 cessus caudatus is bounded anteriorly by the duodenum (upper part 



