99 



lion of some of these substances can be 

 demonstrated. 



Cholesterin, lecithin and the quater- 

 nary ammoniacal bases are substances, 

 which, when under special conditions 

 mixed with cultures of B. tuberculosis 

 exert a dissolving influence on the bo- 

 dies of the microbes. 



The observations of DEYCKS and 

 MUCH (7) on this subject have been 

 unanimously confirmed by posterior re- 

 search. Thus in tuberculosis cultures the 

 freeing of these principles which do 

 diffuse, although slowly, in liquid media, 

 would permit of the dissolving of the 

 microbian lipoids and a consequent dis- 

 persing of the granules. It is, in fact, a 

 general property of lipoids to dissol 

 each other mutually [IVAR BANG (8)]. 



The phosphatides have this property 

 accentuated and the non-satura!ed fatty 

 acids as well as their soluble soaps are 

 very active. 



Although the actual tendency is ra- 

 ther to approach these reactions to the 

 reactions of soluble ferments, v.-e should 

 rather consider them as chemical non- 

 fermentative saponirication or hydroly- 

 sis reactions since they are accelerated 

 by a raising of the temperature incom- 

 patible with fermentative activity. 



Is is what one must conclude from 

 the action of ox-bile an& of several of 

 the lipoids from cod-liver oil which exert 

 a disaggregating and somewhat lytic In- 

 fluence on tubercle bacilli at temperatu- 

 res of approximately lOOoC. 



Therefore «the chemical composition 

 of the tubercle bacillis, its richness in 

 higher alcohols, fats and phosphatides 

 and the diffusion of these lipoids in the 

 culture media explain the morphologic 

 modification of the bacilli and the free- 

 ing of the granulations quite indepen- 

 dently of any fermentative activity. 



4°— Tubercle cultures depelop on 

 culture media of the most different ori- 

 gin and most varied chemical composi- 

 tion. 



Media of animal origin, vegetable 

 media or even media of definite che- 

 mical composition permit the develop- 

 ment of cultures in which the bacilli 

 keep their principal characters: acid- 

 fastness and granular structure. 



This does not mean that modifica- 

 tion in foi-m and structure of the bacilli 

 may not be obtained when the chemical 

 composition of the culture medium al- 

 ters the biological conditions of the germ, 

 j as happens in media with considerable 

 j quantities of glycerin or those to which 

 j lipoids of different o^-igms have been 

 ; added. Bui in these cases the cultures 

 I which develop, considerably modified in 

 j their biological conditions cannot be con- 

 1 sidcred normal. But even so, in some of 

 I them, as in homogenous cultures when 

 j the perturbing cause ceases to act on the 

 ¡ normal development of the culture, it 

 i returns to the original type revealing 

 the microbes with their specific charac- 

 ters. 



in homogeneous cultures the aban- 

 doning of the cultiu'es and the ceasing 

 of daily shaking allows of the formation 

 of a skin composed of bacilli which 

 ¿eacquire their acid-fastness and granu- 

 lar structure. 



The change in reaction > oí the cul- 

 ture medium, which, in cultures of the 

 bovine type, is, according to the obser- 

 vatior.s OÎ TIL SMITH (9), correlated with 

 the term of development of the culture, 

 does not exert any appreciable action on 

 the phenomenon studied, since week 

 old cultures in full maturity and having 

 suffered twice an inversion of the che- 

 mical reaction of the medium show the 

 microbes in perfect state of structural 

 integrity. 



Thus <iuhen a tubercle culture in 

 placed under normal conditions of de- 

 velopment neither the chemical compo- 

 sition of the culture medium nor a mo- 

 dification of the reaction appear to exert 

 an influence in the production of a mo- 

 dification in the morphology of the ba- 



