STREPTOTHRICOSIS. 455 



predominate in cultures and are also very prevalent in experimental lesions. It 

 stains by the stronger aniline dyes in a somewhat irregular manner, is Gram 

 positive and largely and strongly acid and alcohol fast. 



Culturally it is a facultative aerobe and grows on most of the laboratory 

 media. Growth first becomes apparent in from two to four days and progresses 

 slowly. The cultural characteristics are shown in the accompanying table and 

 need not be repeated here. 



Pathogenicity : This organism is pathogenic for monkeys and guinea pigs and 

 by intraperitoneal injection for rabbits. The lesions differ somewhat from some 

 of the other members of the group in that there is much less tendency to sup- 

 puration or other form of tissue necrosis. The lesion is essentially a tubercle- 

 like formation which spreads from the point of inoculation by the formation of 

 other small granules. When studied microscopically these lesions resemble the 

 tubercle quite closely, always contain the microorganism and occasionally giant 

 cells are encountered. The tubercle-like granules occasionally break down and 

 form small pockets of thick granular pus-like material, but this is the exception 

 and granules made up of colonies of the parasite have not been encountered as in 

 the other species. 



No. 11. /S. canis. This organism is probably identical with 8. caprw of Sil- 

 berschmidt. The only important points of difference in the cultures which we 

 have are shown in the table, and consist principally in the difference in reaction 

 in litmus milk. Morphologically and in its pathogenic action S. canis gives 

 very similar results to S. caprw. The same tubercle-like lesions are formed in 

 experimental animals and the close similarity in other respects has led to the 

 conclusion that the two belong to a single species. 



No. 12. 8. chalcea. This is a nonpathogenic species reported by Foulerton and 

 carried along in this work principally as a control. It is distinguished specifically 

 from the other species by morphologic and cultural characteristics, and parti- 

 cularly by its being nonpathogenic for monkeys. 



ANIMAL EXPERIMENTS. 



The following are summaries of our animal experiments. The general 

 results are placed under the discussion of the characteristics of the 

 various species of the microorganisms. A complete summary will be 

 found in the chapter on general discussion and conclusions. 



8. nocardi: 



Monkey No. 8685, inoculated in the abdominal cavity with one loop of a two 

 months' culture and the animal killed 12 days later. Autopsy shows numerous 

 miliary tubercle-like granules extending over the entire surface of the omentum 

 and mesentery with an occasional suppurative process. The pus when pressed 

 out contains small, yellowish-white granules made up almost entirely of the 

 microorganism. 



Monkeys numbered 81'22, 3726, 3114 were inoculated in a similar manner to 

 the above. All showed similar lesions with the exception of monkey No. 3722 

 which gave a negative result. 



Guinea pigs and rabbits inoculated in the abdonimal cavity for the greater 

 part developed similar lesions. Intravenous inoculation in rabbits gave negative 

 results. 



»S'. eppingeri: 



Monkey No. 3665 was inoculated in the abdominal cavity with one loop of 

 a ten days' culture and the animal was killed thirteen days later. Autopsy 

 shows numerous, tubercle-like granules in the lower portion of the mesentery, 



