150 DR. WILLIAM STIRLING. 



lung is made so as to contain a transverse section of a bron- 

 chus we never find any of these embryos in the connective 

 tissue or in the lymphatic tissue which so abundantly accom- 

 panies the bronchi. It is easy to find these small nodules in 

 the vesicular structure passing quite up to the connective 

 tissue surrounding the bronchi, but never in it. This con- 

 nective tissue in the larger bronchi is open in its texture, 

 lying chiefly outside the cartilages, and is accurately mapped 

 off from the adjacent vesicular structure, and in a transverse 

 section of such oUulanised lung many leucocytes are to be 

 found within its meshes. 



Now, how do these embryos reach the lungs, and how can 

 we explain the changes they produce there ? Leuckart 

 maintains that they migrate from the intestine as embryos 

 and pass into those organs in which they become lodged. 

 They are thus said to migrate within their host, after the 

 manner of the embryos of trichina. The trichina embryos, 

 however, follow specially the course of the connective tissue, 

 but it is an interesting and important point that in the case 

 of oUulanus none of the embryos are to be found in the 

 connective tissue around the bronchi. Leuckart did not suc- 

 ceed in finding any embryos in the blood. 



It seems to me that the embryos ultimately find their way 

 and become lodged between the air-vesicles, and that they, 

 by their presence, give rise to an interstitial inflammation, 

 resulting in the formation of the numberless nodules already 

 described. These nodules occur in tens of thousands. As 

 the inflammatory action proceeds the nodules gradually 

 increase in size, encroach upon and obliterate neighbouring 

 air-vesicles, rendering great areas in the lung apparently 

 solid. Each embryo becomes surrounded by a special capsule 

 of condensed connective tissue. Leuckhart found no embryos 

 in the blood in his cases. 



Changes which the embryo undergoes within its capsule. — 

 It is at first coiled up within its capsule, but after a time it 

 loses its mobility and its body degenerates, so that many of 

 the capsules appear to be filled with an oval mass of fine 

 granules. In fact, this mass of granules resembles an ovum 

 undergoing segmentation, and Meissner was led into error 

 by regarding it as an ovum, viz. that of Ascaris mystax, 

 though he left unanswered the quesiton how it got there. I 

 have no doubt also that the ova described by Henle^ as 

 occurring in the cat's lung were simply these degenerated 

 forms of ollulanus. 



The degeneration which the worm itself undergoes is of a 

 ' ' Allgemeine Pathologie,' II, p. 789. 



