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For convenience of description, the topography of the head and 

 body of the pancreas will be separately considered. 



I. Head of the Pancreas. 



The head of the pancreas, as is well known, is formed by the 

 union of its dorsal and ventral anlages about the fifth week of em- 

 bryonic life. By the end of the second month it has already, for the 

 most part, attained its definite form and position, which persist 

 throughout foetal life. Certain of its relations, however, deserve 

 special consideration. These are its relations to the vertebral column, 

 to the liver, and to the transverse colon. 



The relations of the head of the pancreas to the vertebral column 

 were studied by Merkel (9) in median sagittal sections of seven human 

 foetuses varying from 5,3 cm to 36,5 cm, crown-rump length. Merkel 

 concludes that the pancreas in the earlier stages occupies a higher 

 position, opposite the twelfth thoracic vertebra, and that it later grad- 

 ually descends to its definite position in front of the second lumbar 

 vertebra. Merkel's figures show no decided evidence to support this 

 conclusion, however, and on account of the great individual variations 

 it would seem necessary to examine a larger number of specimens. 



So far as the earliest stages in the development of the pancreas 

 are concerned, the primitive position is undoubtedly much higher. The 

 embryo ("R") 5,5 mm. in length, reconstructed by His (6) shows the 

 pancreas anläge opposite the first thoracic segment (protovertebra). 

 There soon follows a rapid descent of the pancreas, however, together 

 with the neighboring thoracic and abdominal viscera and a lengthening 

 of the trachea and oesophagus. In an embryo 7 mm in length re- 

 constructed by Mall (8) the pancreas anläge appears opposite the 

 third or fourth thoracic segment. In embryo "A", length 7,5 mm, 

 reconstructed by His (6), the pancreas anläge is not shown, but the 

 mouth of the bile duct lies opposite the sixth thoracic vertebra. In 

 an embryo 10 mm in length (Mall collection No. 114), the head of 

 the pancreas apparently lies about the level of the ninth thoracic 

 vertebra. The process of descent is evidently completed about the sixth 

 week. In a specimen 16 mm in length (Mall collection No. 43) the 

 head of the pancreas already lies opposite the first and second lumbar 

 vertebrae. In mid-sagittal sections of twenty-five embryos varying 

 from 2,1 cm to 48 cm in length, I find that in general the head of 

 the foetal pancreas lies opposite the first and second lumbar vertebrae, 

 occasionally extending up as high as the twelfth thoracic, or as low 

 as the third lumbar. Individual variations are numerous, but I have 



