DIFFERENTIAL DIAGNOSIS 59 



less well defined capsule of embryonic and further developed 

 connective tissue cells and filaments. 



" On microscopic examination, the kidneys show slightly 

 swollen epithelial cells of a beginning parenchymatous degen- 

 eration to well pronounced disintegration of the renal 

 epithelium of acute nephritis. The degree of degeneration 

 depends, as a rule, upon the course of the disease. If a bird 

 succumbs suddenly or in the course of a few hours the morbid 

 changes are either not apparent at all or but slightly pro- 

 nounced, while, on the other hand, the duration of three or four 

 days to a week results in an acute exudative nephritis. The 

 swollen or degenerate epithelium of the tubules surrounds irreg- 

 ular masses of coagulated exudate and white blood corpuscles, 

 among which are numerous short chains of streptococci. In 

 very acute cases with sudden death the liver shows extreme 

 hyperemia. The cells have a slightly granular appearance in 

 addition to the fatty infiltration usually seen in the liver of 

 well kept fowls. When death does not occur until after 

 twenty-four hours the liver cells also show parenchymatous 

 or fatty degeneration ; their outlines become indistinct, the 

 body very granular, and the nucleus takes the stain but 

 faintly. Interlobular and intralobular collections of round 

 cells and leucocytes appear, and in more chronic cases centers 

 of coagulation necrosis may be seen. The lungs become 

 hepatized. The walls of the bronchioles are thickened and the 

 streptococci may be seen in the minute capillaries. The air 

 cells are filled with plasma, red blood corpuscles and epithel- 

 ium, among which the microorganism is easily detected." 



§ 44. Differential diagnosis. This affection must be 

 differentiated from fowl typhoid and chicken cholera. The 

 positive diagnosis of each must rest with the etiological 

 factor. A number of diseases of fowls have been described 

 from various places in Europe and Africa, but none of them 

 seem to be caused by a streptococcus. 



§45. Prevention. The separation of the well from the 

 diseased fowls and placing them in uninfected houses or yards 



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