474 Mr. C. B. Lockwood. Arteries of the Abdomen 



" The Development of the Arteries of the Abdomen and 

 their Relation to the Peritoneum." By C. B. Lockwood. 

 Communicated by W. S. Savory, F.R.S. Received 

 November 18, 1884. Read December 11. 



Anatomists who have written concerning the arteries of the abdo- 

 men and their relations to the peritoneum display considerable 

 divergence of opinion. This want of uniformity may perhaps be due 

 to the fact, that owing to the complications of the serous membrane 

 ifc is hard to trace the course of the vessels without seriously disturbing 

 their relations. Another and most important reason is, that so far as 

 I am aware, no methodical attempt has been made to elucidate them 

 upon developmental grounds. The importance of such an endeavour, 

 in this case, is made clear by a moment's consideration. If the 

 alimentary tract of one of the lower vertebrates be examined a very 

 simple arrangement may be found ; most probably a straight bowel 

 suspended by a simple mesentery. Along the spinal attachment of 

 this serous fold a large blood-vessel extends, and branches descend 

 from it to supply the bowel. When such a scheme as this is compared 

 with that which obtains in the human subject, it is evident that many 

 complicated changes have taken place, and it will be found that the 

 vase alar supply of the abdominal organs participates in every 

 change they undergo. In this paper it is proposed to consider the 

 various events which occur, and their effects upon the course of the 

 arteries. 



It seems unnecessary to state that so far as alterations in the shape 

 and position of the various portions of the alimentary canal are con- 

 cerned, there is hardly any difference of opinion; they are well known 

 and have been frequently described. The abdominal blood- vessels^ 

 and the serous membrane have attracted less attention. 



As a preliminary, it may be stated that as the development of the- 

 intestines and their appendages, the liver, pancreas, and spleen, has 

 such an important influence upon the arteries, it will be necessary to 

 refer to them at some length. 



Owing to the difficulty of obtaining and manipulating human 

 embryos young enough to display the alimentary tract in its earliest 

 stages, I found it convenient to study these by examining embryo rats, 

 mice, chicks, &c. Evidently the truth of observations made in this 

 way requires constant verification by comparison with what can be- 

 made out in the human subject. 



When embryo chicks are used changes prior to the third day need 

 not be taken into consideration ; and although the following facts are 

 all well accepted, perhaps I may be permitted to narrate them, inas- 



