332 IVAN C. HALL AND LILLIAN J. ELLEFSON 



selective inhibition by gentian violet. Incidentally the Gram- 

 positive sporulating aerobes, among which occasional forms 

 capable of giving positive presumptive tests occur, are also 

 inhibited. 



The early literature dealing with the germicidal and anti- 

 septic action of dyes has been sufficiently reviewed in a former 

 publication (1914). Churchman's (1912) work, which was the 

 point of departure for that paper, and which enabled him to 

 state that a majority of Gram-positive organisms are inhibited 

 in their growth by gentian virlet, whereas most Gram-negative 

 organisms grow well in its presence, dealt mostly with aerobic 

 cultures. Cei'tain anaerobes, e.g., two strains of B. tetani, 

 were found by him to follow the rule as we have already amply 

 confirmed (Hall and Taber, 1914). But others, namely B. 

 welchii and B. sporogenes, were noted as exceptions to the gen- 

 eral rule, i.e., while Gram positive, they were classed as re- 

 sistant to the dye in the concentration used. 



Inasmuch as we have undertaken a comparative study of a 

 series of cultures of organisms belonging to the group oi *. J ram- 

 positive sporulating anaerobes, it seemed that it would be of 

 interest to determine what, if any, difference could be found in 

 their behavior and growth in the presence of gentian violet. As 

 often happens, this study, which was undertaken purely from 

 academic motives, was nearly completed before we appreciated 

 its very pertinent practical utility. 



THE ACTION OF GENTIAN VIOLET UPON CERTAIN GRAM POSITIVE 

 SPORULATING ANAEROBES 



The cultures of anaerobes tested came from various sources 

 as indicated below. Most of them have been tentatively iden- 

 tified but we do not wish to emphasize the question of identity 

 of any, except such as are designated "confirmed," since we 

 have found certain atypical features in some of the cultures 

 which may necessitate re-naming them. All are Gram-positive 

 sporulating obligative anaerobic bacilli and, with the exception 

 of B. tetani and B. putrificus, of clostridial morphology. The 



