BACILLI IN CHRONIC INFECTIOUS DISEASES. 427 



apparently give off lateral ramifications. (This description of the morphol- 

 ogy gives rise to the suspicion that the microorganism described by Nocard 

 is a microscopic fungus rather than a bacillus.) According to Nocard, the 

 branching is more apparent than real, and is in fact a false cuchotomization, 

 such as is seen in the genus Cladothrix. 



Stains best by Weigert's method ; is decolorized by Gram's method. Does 

 not stain readily with most aniline colors. 



Biological Characters. An aerobic, non-motile bacillus, which does 

 not grow in nutrient gelatin at the room temperature. Grows in the usual 

 culture media at a temperature of 30 3 to 40 C. Forms small oval spores. 

 Is destroyed in ten minutes by a temperature of 70 C. Upon the surface 

 of agar it forms irregular, opaque, yellowish-white colonies, which are 

 thickest at the margin, have a dull, dusty- looking, mammillated surface, 

 and after a time become confluent, forming a thick, wrinkled, membranous 

 layer. Upon potato development is rapid in the form of prominent, dry, 

 pale- yellow plaques. In bouillon whitish flocculi are formed, most of which 

 fail to the bottom, while some float upon the surface, where they form dry, 

 dusty-looking, rounded pellicles of a dirty-gray color with a greenish reflection. 



Pathogenesis. The guinea-pig is the most susceptible animal. When 

 injected into th^ peritoneal cavity of one of these animals it produces, in 

 from nine to twenty days, lesions which closely resemble those of miliary 

 tuberculosis. At the autopsy the peritoneum is found to be covered with 

 nodules, in the centre of which the bacillus is found in tangled masses ; the 

 liver, spleen, kidneys, and intestine are also studded with pseudo-tubercles, 

 but these are only found in the peritoneal coat and not in the parenchyma 

 of the various organs, or in the organs of the thoracic cavity. Intravenous 

 injections give rise to lesions similar to those of general miliary tuberculo- 

 sis, the organs generally containing a considerable number of nodules, in 

 the centre of which tufts of bacilli are found. In cattle and sheep similar 

 lesions result from intravenous injections, but without causing the death of 

 the animal. The dog, the cat, the horse, the ass, and the rabbit are immune. 

 Subcutaneous inoculations in guinea pigs produce an extensive local abscess, 

 followed by a chronic induration of the neighboring lymphatic glands. 



