452 CONTAGIOUS PLEUEO-PNEUMONIA 



irritant or corrosive fluids. Where these agents may be 

 excluded special attention should be paid to the condition of 

 the pleura and to the distribution of the disease, careful notes 

 being made of the lobes involved. Next in order come the 

 peculiar perivascular and interlobular thickening and the 

 thrombosis of the veins. Care should be taken not to con- 

 found mere clots with adhesive thrombi. In acute pleuro- 

 pneumonia, after death, the arteries are usually distended 

 with clots. The different features of the hepatized and 

 edematous portions of the lung tissue should be carefully 

 noted. I,astly, the peculiar exudation and infiltration in the 

 connective and fatty tissue of the dorsal mediastinum and of 

 the embedded glands should not be overlooked. With the 

 microscope the peculiar dense cell masses of the diseased con- 

 nective tissue should be looked for and the nature of necrotic 

 tissue determined in case microscopical appearances are no 

 longer reliable owing to hardening processes. 



Finally it should be borne in mind that the lesions of 

 broncho-pneumonia and the interlobular changes which may 

 follow it may coexist with contagious pleuro-pneumonia, and 

 that both kinds of lesions may be encountered in the same 

 lungs. Hence, great caution must be exercised in expressing 

 an opinion when only a small portion of the lungs are pre- 

 sented for examination, because only that portion which is 

 affected with broncho-pneumonia may have been submitted. 



§ 357- Preventive inoculation and eradication. In 

 Europe inoculation has been practiced for a long time as the 

 principal means for combating pleuro-pneumonia. As early 

 as the beginning of the last century it was proposed in Ger- 

 many by Hausmann and others. Its employment was greatly 

 increased by the investigations which were made in 1850 by 

 Wilhelms in Holland and which were published in 1852. 

 Since that time these inoculations have been practiced in 

 nearly every country. The literature on the subject is very 

 copious. 



The advocates of inoculation, among whom we may 



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