161 



Casual Infection of Various Organs. {See Plate 1.) 



In South Africa drenching is the favourite way for immunising. This 

 absolutely unscientific method consists of pouring pleuro-pneumonia virus, 

 either pure or diluted, from a bottle into the slightly opened mouth of 

 the animal. Since Nocard's investigations have shown that pleuro- 

 pneumonia virus remains absolutely inactive when passed through the 

 stomach, it is strange that sach a procedure should be employed and 

 confer a certain immunity. It has been possible to demonstrate that this 

 method is frequently accompanied by comphcations ; sometimes pleuro- 

 pneumonia was the result, sometimes pathological anatomical lesions 

 appeared, which were caused by the virus entering a defect in the tissue 

 and there producing the usual progressive process. Logically one can 

 expect the most dangerous pathological changes ; I wish, however, to 

 draw attention to one case only, referred to already by Theiler* ; a speci- 

 men from this case is preserved in our museum. 



The specimen is a slice through the trachea, oesophagus, etc. The 

 virus must have entered near the base of the tongue, for according to the 

 post-mortem record, a huge oedematous swelling was found from the base 

 of the tongue, along the throat as far as the bifurcation of the trachea. 

 Clinically, the animal showed blocking of the oesophagus, which was seen 

 by the animal bringing up through its nostrils the water it had drunk. 

 From the specimen, following details have been made out : — One of the 

 rings of cartilage, probably the thirtieth, judging from the position of the 

 oesophagus, is surrounded in a loose spongy connective tissue, or better, 

 in a fibrous tissue. Single groups of fat lob.ules are intruded between the 

 gelatinous lymph spaces. The upper margin of the tracheal ring is inter- 

 rupted by a space of 1^ mm., through which the peritracheal tissue 

 communicates by an isthmus with a tumour protruding 2-4 cm. into the 

 trachea and spreading to the middle of both of its sides. The tumour 

 consists of a coarse fibrous supporting tissue, containing broad lymph 

 spaces with thickened walls ; the whole is covered by a strongly folded 

 epithelium-like layer. The mucosa of the trachea is slightly thickened, 

 its structure is similar, though not developed to the same degree. The 

 oesophagus is difficult to recognise as such, for everywhere a similar tumour 

 protrudes itself within the otherwise normally folded mucosa. The lesions 

 observed macroscopically in the mucosa are sponge-like plicae, covered 

 by a fine white membrane, below this a jelly-like filling. The muscularis 

 is thickened, its fibres are dissociated, in structure it appears honey- 

 combed and it is almost separated from the fibrosa by a few lymph spaces. 

 Two blood vessels close by are thrombosised ; their walls are greatly 

 thickened. 



The intermuscular tissue of the M. sternohyoideus and sternomandi- 

 bularis is dissociated in the usual manner. The tissues of the fossa 



* Loco cit., pages 361 and 30(5. 



