157 



lymphogene or haematogene channels in the majority of cases. Accord- 

 ing to Theiler* it is possible to produce acute pleuro-pneumonia of the 

 peritoneum with all the characteristic lesions by intraperitoneal injection 

 of the blood of a calf suffering from the natural disease. Hutcheonf goes 

 a long way to prove the lymphogene or haematogene transportation of the 

 virus ; he states that if a calf suffering from pleuro-pneumonia be castrated 

 or ear marked, typical pleuro-pneumonia tumours will be found at the seat 

 of the wound. 



Except for a slight desquamation of the epithelia of the synovialis 

 no remarkable lesions were present. A small deposit of fibrine on the 

 defects was demonstrable by staining. The flicae synoviales are free 

 from villi, but it is not possible to state whether the changes are constant, 

 as only a small portion of the synovialis was at my disposal. From the 

 physiological point of view this would be possible, for the negative pressure 

 in the articulation is reduced. Those capsules of joints which have been 

 invaded by the way of the blood vessels present quite different lesions. 

 In normal histology one learns that the stratum synovialis is easily destroyed, 

 and that it sooner succumbs to inflammatory processes than any other tissue. 

 The great quantity of capillaries and large number of cells it contains present, 

 of course, great possibilities for attack ; the pleuro-pneumonia process 

 naturally acts on these membranes. A deposit of fibrine usually con- 

 taining crowds of leucocytes is exudated on the denuded membrane of the 

 synoviahs. The plicae are reflected, often adhering to each other, or two or 

 more are enveloped in masses of exudate. The capillaries are distended, and 

 form dense reticulations and loops. These lesions are not found on all 

 parts of the synovial membrane. The underlying connective tissue is 

 loosened, filled with leucocytes and its otherwise regular arrangement is 

 disturbed, the fibrillae running in all directions. An invasion of emigrants 

 following the course of the capillaries takes place only in the lower stratae 

 of the synovialis, the upper layers remaining free. In the fibrosa the 

 lesions are nearly the same, only there is less infiltration. The parasy- 

 novial tissue is not affected, so that the haematogenic nature of the 

 infecti on is evident. Here it becomes clear that, when pleuro-pneumonia 

 virus is exuded by any means, the accompanying lesions are totally 

 different to those we have hitherto studied. It is consequently easy to 

 understand that these changes readily heal, in contrast to the other 

 lesions, where the blocking of the blood vessels causes necrosis and requires 

 peripheric restitution. 



Macroscopic Lesions in the Intestines. 



Shortly before completion of this paper I had the good fortune to 

 observe the following case. 



CASE 10. — 0x662, injected with 0-5 c.c. culture from virus "Dalton," 

 2J cm. from apex of tail. 



* The Transvaal Agricultural Journal, Vol. II, No. 7, 1904, page 380, 

 ^ Vide Theiler, loco cit., page 361. 



