Dr Barclay-Smith, Extreme Visceral Dislocation. 25 



very early in the evolutionary history of the intestine, being found 

 in the reptiles 1 . 



It is a significant fact that in animals with well developed 

 coeca, agminated masses of adenoid tissue, or adenoid tissue diffused 

 throughout the mucosa, are nearly always a conspicuous feature of 

 this part of the gut, being present to a very much greater extent 

 than in any other part of the tube. 



It is highly probable that these aggregations of adenoid tissue 

 are specially concerned in restraining bacterial activity ; that they 

 are local collections of leucocytes whose especial role is phagocytic, 

 and that there is a constant war to the death between them and 

 the bacteria infesting the caecum. 



It is a fact, pregnant with meaning, that the adenoid tissue is 

 usually most marked at the csecal apex 2 , viz. at the spot where 

 the stay of the contents will be most prolonged. 



The coecal accumulations of adenoid tissue are then probably 

 efficient in restraining undue bacterial increase, but they will 

 afford little or no hindrance to the invasion of the small gut. 



The ileocolic valve, though competent to hinder regurgitation, 

 would obviously furnish no effectual bar to the passage of micro- 

 organisms. 



But again, the protective adenoid tissue makes its appearance 

 in the form of those remarkable collections known as the agminated 

 glands or Peyer's patches, which are such conspicuous features at 

 the distal end of the small intestine, and concerning whose func- 

 tional interpretation no suggestion, as far as I know, has yet been 

 offered. 



If there is any truth in the suggestions offered in this paper, 

 they have an important practical application as regards the large 

 intestine as found in man. 



From the nature of his diet a reliance on extrinsic digestive 

 aid such as is furnished by bacteria is no longer a physiological 

 necessity. The statement is perhaps a bold one, but I am con- 

 vinced that the large intestine is practically a useless encumbrance 

 to him. From his herbivorous ancestors he has inherited not only 

 a bacteria infested colon but a tendency to a ceecal diverticulum. 

 Further, one great penalty he has had to pay for assuming the 

 erect posture is to add yet another factor, viz. gravity, to favour 

 the stay of the intestinal contents at the proximal end of the large 

 gut. He has done his best, as it were, to adapt himself to these 

 untoward circumstances. Though probably the tendency to csecal 

 diverticulation is yet strong within him, this appendage to the gut 

 has dwindled as rapidly as possible to a vermiform appendix with 



1 Gegenbaur, Vergleichende A7iatomie der Wirbelthiere, 1901, Vol. n., p. 415. 



2 Berry, Journal of Anatomy and Physiology, Vol. xxxv., p. 83. 



