172 Report on the Pathological Anatomy of Pleuro-pneumonia. 
are very easily recognised, and no energy was required to master 
the anatomical details, since any one can recognise the disease 
post-mortem. Therefore the English school has neglected this 
department of study, having preferred to go into the wider field 
of theoretical speculation in order to determine the cause of the 
disease. 
Professor Brown,* in an admirable brochure on the subject, 
gives a very clear sketch of the disease, and well describes the 
most striking morbid appearances. As to the exact essence of 
the disease, he says : — 
" Pleuropneumonia is essentially determination of blood to the lungs, and 
exudation of liquor sanguinis, that is to say, blood deprived of its red particles, 
into the connective tissue which is everywhere distributed throughout the 
lung structure, existing abundantly between the lobules and on the surface of 
the lungs under the pleural membrane. Exudation occurs also on the surface 
of the pleura, but the chief deposit takes place under it, and causes its eleva- 
tion from the lung tissue just as the exudation between the lobules causes 
them to separate from each other." 
And again he says : — 
" Inspection of those organs of the animal body which are principally im- 
plicated in the disease (the lungs), however minute and complete it may be, 
only puts us in possession of a knowledge of effects. It is evident enough that 
the lungs have received an excess of blood, and that a large quantity of the 
circulating fluid has been exuded into the tissue of these organs ; but the 
really important question is, What circumstances conduced to these results ? 
And the only answer which the pathologist can offer is contained in a some- 
what vague reference to ' blood poisoning.' As in other contagious diseases 
the blood of the animal affected with pleuro-pneumonia becomes charged 
with some poisonous material, which is excreted by the vessels of the lungs : 
for example, in small-pox, the virus is excreted by the skin, and the poison of 
cattle-plague by the mucous membrane. In each case it is impossible to define 
the determining causes. We can no more understand why some of the con- 
stituents of the diseased blood are poured out in large quantity in the fibrous 
tissues of the lungs in pleuro-pneumonia than we can comprehend the ultimate 
cause of the distinctive eruptions in the various exanthematous diseases." 
Mr. Fleming f says, " Pleuro-pneumonia is a specific and con- 
tagious fever peculiar to bovine animals. In its essence it is a 
malignant fever allied to the general eruptive diseases." 
Professor Walley J gives an elaborate account of the post- 
mortem changes of zygomatic pleuro-pneumonia. He divides 
the progress of the disease into three artificial and rather fanci- 
ful chronological stages. The general characters of the first 
being : — 
" Increase in weight, bulk, and friability ; diminution in resilient power, 
and consequently increased resistance to inflation, and decrease in crepitation 
* ' Obs. on the Lung Disease of Cattle known as Pleuro-pneumonia.' 
t ' A Manual of Vet. Sanitary Science and Police.' London, 1875. 
X 'Vet. Jouru.,' May, 1870. 
