614 INFECTION AND IMMUNITY. 



Bacilli from "Milk bacilli" and "butter bacilli" are acid-fast or- 

 Mil ni ^ tter ganisms resembling the tubercle bacillus morphologi- 

 rass. ca jiy^ j n i n j ec ting milk into guinea-pigs as a test for 

 tuberculous contamination, Petri occasionally noted, as 

 a consequence, a thick membranous growth which en- 

 cased the liver and spleen and bound the coils of intes- 

 tines together. The omentum was thickened, and this 

 structure and the mesenteric lymph glands contained 

 nodules. In pure culture the organism is pathogenic for 

 guinea-pigs only when given in large doses, and may kill 

 the animals in several weeks with the anatomic changes 

 noted above. Its virulence is increased by the simul- 

 taneous injection of butter. It is not pathogenic for 

 man ( Herbert ) . 



Moeller cultivated organisms resembling the tubercle 

 bacillus from timothy ( timothy bacillus ) , from manure, 

 and a third (grass bacillus II) from the dust of a 

 manger. The last is marked with great pleomorphism, 

 thread formation and motility in young cultures. 



The leprosy bacillus and the B. of Lustgarten which 

 resemble the tubercle bacillus will be considered later. 



PSEUDOTUBERCULOSIS IN ANIMALS. 



Although some of the organisms described above are 

 often called pseudotubercle bacilli, the term pseudo- 

 tuberculosis is now applied somewhat specifically to a 

 nodular disease occurring in rats, mice and sheep (and 

 perhaps in other domesticated animals), and in which 

 organisms differing from the tubercle bacillus in stain- 

 ing and culture properties, morphology and pathogenic- 

 ity, are found. The clinical course and anatomic 

 changes are similar in the three animals mentioned, al- 

 though the organisms are different. The lymph glands 

 near the infection atrium become enlarged chiefly by a 

 cellular infiltrate rather than extensive proliferation of 

 fibrous tissue. The nodules undergo a soft caseation 

 very early and rarely show calcification. The infection 

 finds its way to other sets of lymph glands and may be- 

 come more or less generalized with the formation of 

 smaller and larger sized nodules. 



Rats and Pseudotuberculosis of rodents, occurring spontaneous- 

 Mice, ly in rats, guinea-pigs, rabbits and cats, is caused by an 

 organism of considerable pathogenicity, and may occur 

 in epidemic form in laboratory animals. Chickens also 

 may contract the disease. Intraperitoneal inoculations 

 in guinea-pigs are fatal in a few days. Spontaneous in- 

 fection takes place through the intestinal tract, and re- 

 gional organs show the principal changes. The liver and 



