148 DR. WILLIAM STIRLING. 



and it is easy to see how the vesicular texture of the lung is 

 encroached upon by these nodules. The letter d points to 

 a transverse section of an artery, and shows the immense 

 thickening of the middle coat, which will be alluded to later. 



Although several worms may exist within each nodule, 

 each individual worm has around it a special capsule, and 

 there is never more than one worm within a capsule. It lies, 

 as it were, coiled up within a little cyst of its own, and several 

 of these cysts are held together by the reticular tissue around 

 them. The cyst itself consists of connective tissue. It is 

 generally round in shape, and the coiled-up embryo either 

 occupies it entirely or there is a narrow space left between 

 it and the wall of the cyst, which is filled with a clear 

 fluid. Leuckart^ remarks that the lungs are studded 

 with a greater or less number of small cysts, which enclose 

 one or more embryos. The wall of the capsule, he continues, 

 is of such a considerable thickness that it not unfrequently 

 exceeds in diameter two or three times that of the space in 

 which each worm lies. Now, it seems to me that there is a 

 distinct thickened layer of connective tissue round each 

 worm, and the other reticular tissue around each embryo or 

 group of embryos must be regarded as the result of an 

 interstitial inflammation, and thus it is that several worms 

 come apparently to be enclosed within each nodule. These 

 nodules are not of any definite size or shape, though gene- 

 rally somewhat rounded, but they are often of quite irregular 

 outline. 



These nodules at first sight give the lung the appearance 

 of one affected with miliary tuberculosis, for which one is at 

 first very apt to mistake them. 



If we examine a similar section taken from immediately 

 under the pleura, but in an earlier stage, when no pleurisy 

 exists, we find that these nodules always give rise to little 

 elevations immediately underneath the pleura, presenting 

 exactly the same appearances as Burdon-Sanderson has 

 described in the case of tuberculosis. 



Fig. 2 shows two nodules taken from the substance of the 

 lung, and examined with obj. iv, oc. 3, Hartnack, h repre- 

 sents a cyst with a worm coiled up within it, and a shows a 

 degenerated worm. The reticular structure of the nodule is 

 well brought out, and the outer layers present that compressed 

 appearance not unfrequently observed in true tubercle. Th( 

 epithelium around the margins of the mass is often found ti 

 be proliferating. This figure also shows how these nodulet 

 by their growth gradually encroach on the lumen of the air 

 • Loc. cit., p. 103. 



