162 



jugiilaris are enlarged and metamorphosed into a gelatinous mass. Several 

 larger blood vessels are thrombosised here. It is evident that the specimen 

 is a portion of a peritracheal and perioesophagal oedema. 



Microscopical Lesions. 



The tumour in the trachea, the changes in the mucosa, the perichon- 

 drium and the cartilage offer most interest ; the cartilage is absolutely 

 normal, a few foci of leucocytes are remarked in the perichondrium ; the 

 peritracheal tissue is no longer recognisable, dense layers of a tissue 

 containing very many cells surround the cartilage, between the layers are 

 insulae of blood vessels and typical condensations of leucocytes and 

 fibrine. All stages of inflammation such as described as above can be 

 noted, likewise muscle atrophies and resorptions. Examined with a low 

 power, large round deeply stained rings or reticulations become visible. 

 The tumour, which half fills the trachea, consists of a stroma of connective 

 tissue in which pleuro-pneumonia lesions with all their peculiarity are 

 observed. The inner surface consists of a band composed of leucocytes, 

 fibrine, blood vessels, and connective cells; within this there is a layer of 

 transverse sections of vessels, connective tissue with reticulations of elastic 

 fibres fills the interior. The mucosa has entirely disappeared ; the con- 

 nective elements appear to be derived from the perichondrium, as the 

 connective trabecles originate on the perichondrium to proceed into the 

 tumour, where they form reticulations. In the different layers of the 

 oesophagus one finds similar lesions. As the tumour only represents a 

 combination of all pleuro-pneumonia lesions on the connective elements 

 of various organs, the illustrations will demonstrate all the changes in 

 more eloquent manner than would a recapitulation of what has already 

 been said. 



CoNCLUSiOiSrs. — Pleuro-pneumonia virus has an absolutely specific 

 effect on the tissues, it chiefly attacks the connective elements, the lesions 

 which can be demonstrated histologically are characterised by the follow- 

 ing phenomena : — 



(1) The virus multiplies in the lymph vessels after having invaded 



them (lungs, muscles, subcutaneous connective tissue, lymph 

 glands, intestines and mucosae and serosae generally). It 

 causes an inflammatory process, which presents itself micro- 

 scopically as lymphangitis serofibrinosa , lymphothrombosis, emigra- 

 tion of leucocytes, etc. 



(2) The process proceeding only along the lymph vessels {per con- 



tinuitatem) involves also the lymph spaces of the walls of 

 blood vessels, a peri- and mesoarteriitis, with formation of 

 thrombus results. Thick rings of leucocytes with deposits of 

 fibrine surrounding the blood vessels at a short distance in 

 circular symmetrical arrangement give quite a characteristic 

 appearance to the microscopical lesions. 



