KKI.ATloN To INFECTIOUS IHSKASKS. !.') 



is chemical in character, it becomes evident that no 

 one is jn.-tilied in saying that one germ is the sole source of 

 that poison. Surh a statement would be as unwarranted 

 a- one that the oilier tnr is the solo source of call'ein, or 

 that the strvchnos Ignatii is the only species of the nat- 

 ural order Loganiacea- which produces a convulsive poison. 

 In other words, the specific cause of a given disease is not 

 to lie determined wholly by the morphology of the germ, 

 but I iv the character of the chemical poison which is the true 

 materics morbi. 



Bacteria cannot be classified, so far as their causal rela- 

 tionship to disease is conecrned (and this is the most im- 

 portant knowledge to be gained from them), until we know 

 the nature of their chemical products, for it is by virtue of 

 these that the germs have any causal relationship to dis- 

 ease. 



It is possible that two germs maybe unlike in form, and 

 yet they may produce poisons which are identical or those 

 which are very similar in their effects upon man. One 

 germ may lie stained by GRAM'S method and another fail 

 to be acted upon when so treated ; but this does not prove 

 that their chemical products are totally unlike. This is 

 not only a possibility, it is a fact which has Ix-en demon- 

 strated repeatedly, both with pathogenic and non-pathogenic 

 organisms. A few illustration* may IK' given here: The 

 yeast plant is not the only microorganism which will pro- 

 duce alcohol in saccharine solutions. The same prodtiet 

 results from the growth of the bacterium Bisehleri, bac- 

 terium coli commune, bacterium ilei, bacterium ovale ilei, 

 bacterium laetis aerogenes, and others (NENCKi). Mor- 

 phologically, there are marked differences lietween the yca.-t 

 plant and these bacteria, but they alike produce alcohol. 

 More than a do/en germs, including lx)th mierococci and 

 bacilli, are capable of generating lactic acid. Some of these 

 prodiur an acid which is optically inactive; others, one 

 which is dextro-rotatory; and others still, one which is hevo- 

 rotatory. The tetanus germ of KlTASATo and that of 

 TDBBONI and GAOTAHI are known to be different. Cultures 

 of the former in bouillon are virulent, while those of the 



