DIFFERENCES BETWEEN ACID-FAST BACILLI 257 



(Lubarsch). Giant cells, epithelioid cells, and caseation are all said 

 to occur. In all animals injected with the grass bacillus a negative 

 reaction to tuberculin is obtained, Moeller has isolated a grass 

 bacillus, No. ii. (from the dust of a hay-loft), which he considers 

 essentially different from the Timothy bacillus. The colonies are 

 moist and sticky, become confluent, and are yellow in colour. It 

 loses its acid-fast properties in old cultures. Its pathogenic pro- 

 perties are most marked when cultured in milk. It frequently 

 shows marked polymorphism. In culture it is like the butter bacilli. 

 Freymuth has shown that the changes this organism sets up in 

 cold-blooded animals are indistinguishable from true tuberculosis. 

 An acid-fast bacillus similar to grass bacillus No. ii. has 

 recently been isolated by Moeller from milk. A variety of the 

 grass bacillus has also been found by Moeller in the excreta of 

 animals, and is therefore termed the manure bacillus (mist bacillus). 

 This acid-fast bacillus has been isolated from the fresh excreta of 

 cattle, and bears a morphological and tinctorial resemblance to the 

 Timothy bacillus, whilst in cultures it is like grass bacillus No. ii. 

 It has certain pathogenic properties. It is possible that most of 

 the acid-fast bacilli found in milk and butter have their origin in 

 the soil or vegetation. 



Differential diag-nosis. — This brief record of the acid-fast bacilli 

 is enough to show that there exist a large number of bacilli, which 

 on occasion may be present in milk or milk products, having char- 

 acters which ally them closely to the tubercle bacillus. Moeller 

 holds that the primitive form is the grass bacillus, and that the 

 butter bacillus, manure bacillus, etc., are varieties thereof The 

 main points of distinction between this group and the true tubercle 

 bacillus are five. 



First, the tubercle bacillus shows a fairly uniform manner of 

 growth. 



Secondly, it requires incubation temperature. 



Thirdly, it is unique with respect to its excessively slow gro\%'th. 



Fourthly, it is as regards growth and propagation a parasite. 



Fifthly, on inoculation it produces pathological cellular changes 

 distinct from the nodular new growths following inoculation 

 of acid-fast bacilli. In particular this is true, as far as is 

 known at present, in regard to the human organism. 



In a sentence, the acid-fast bacilli differ from the tubercle 

 bacillus in three main particulars, viz. : morphology, conditions 

 of development (chromogenicity, rapidity of growth, and wide 



R 



