ACID-FAST GRASS BACILLI 365 



six hours, are scale-like and greyish-white or yellow in colour. It 

 grows best on glycerine agar. It grows slowly in milk, but does not 

 coagulate it. Under certain conditions its growth in artificial media 

 is very similar to the tubercle bacillus, which, however, does not thrive 

 at room temperature. As regards pathogenic properties, the grass 

 bacillus is almost identical with the Petri-Kabinowitsch butter 

 bacillus in its effects on guinea-pigs. It has somewhat different effect 

 on rabbits, producing a condition difficult to distinguish from true 

 tuberculosis (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. 2 (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. 2, 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 excreta of cattle and other animals, and 

 bears a morphological and tinctorial resemblance to the Timothy 

 bacillus, whilst in cultures it is like grass bacillus, No. 2. On agar 

 these organisms grow in a similar manner, but bouillon does not 

 become turbid with the growth of the mist bacillus. It has certain 

 pathogenic properties. When injected into guinea-pigs, nodules 

 resulted ; but they contained few epithelioid cells. The true radial 

 arrangement of the bacilli occurs, however. It is possible that most of 

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

 soil or vegetation. 



Differential Diagnosis. 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 growth. 



