448 MUOOITS MEMBRANES. 



subsequent resolution of the infiltrated matters upon the ulcerated 

 surface. Tlie specific, "tuberculous" element, is accordingly 

 quite subordinate in tuberculosis of the intestines. But it would 

 be a great mistake to suppose it wholly absent. Careful investi- 

 gation shows — 1st, The presence of a certain number of miliary 

 nodules in the tunica adventitia of all the non-capillary vessels, 

 and especially of the arteries in the neighbourhood of the ulcer. 

 2nd, The strictly tuberculous nature of those granulations which 

 occasionally spring up on the opposite surface of the intestinal 

 wall, in the subserous and serous connective tissue, and 

 which enable us to ascertain from the outside, the exact position 

 of the morbid changes in the mucous membrane. The observa- 

 tions recorded in § 115, led me to investigate these struc- 

 tures very thoroughly ; and I have assured myself that here too, 

 it is the lymphatics which undergo tuberculous degeneration, 

 and that the sheaths of the vessels are so manifestly chosen by 

 the tuberculous products, only because they also contain the 

 efferent lymphatics of the bowel. 



The development of miliary nodules upon the branches of 

 the vessels or lymphatics is of especial moment in the present 

 instance, inasmuch as it determines the direction in which the 

 ulcer of the intestinal mucous membrane must extend. For, in 

 marked contrast to the invariably axial configuration of the 

 typhoid ulcers, which do not overstep the limits of a Peyer's 

 patch, the tuberculous ulcers exhibit a decided tendency to 

 spread transversely. They are always tending to become zonu- 

 lar ; originating in Peyer's patches, where also they attain their 

 greatest width, they push their way over the lateral margins of 

 the patch, till their extremes unite on the opposite side of the 

 bowel. If we compare the distribution of the blood-vessels with 

 this mode of extension, we cannot fail to see a certain parallelism 

 between them. The arteries and veins reach the bowel betweeii 

 the layers of the mesentery, on the side opposite to the Peyer\s 

 patch ; from this point they radiate in an arborescent form, 

 their trunks and main branches coursino* ti'ansverselv across the 

 intestinal tube, while their finer ramifications meet on the outer 

 side of the canal, where the patches are situated. The vascular 

 territories of the intestinal wall are accordingly transverse and 

 not axial, and any morbid change which is conterminous with a 

 yascular area, must eo ipso extend in a transverse direction. 



