MORPHOLOGY AND BIOLOGY OF BACTERIA. 29 



of bacteria in the process of digestion is not indispensable. 

 On the other hand, the far-reaching bacterial decomposi- 

 tion of albumin, the formation of organic acids and of an 

 abundance of gaseous products, not rarely give rise to 

 severe digestive disturbances. The formation of hydrogen 

 sulphid may cause intoxication from the gastro-intestinal 

 tract (hydrothionemia), and in individual cases also hydro- 

 thionuria. Bacterial decomposition of urea is the cause of 

 cystitis ; and the formation of ga"s in the bladder by bacteria 

 may result in pneumaturia. Cadaverin and putrescin may 

 result from putrefaction in the intestine or in bronchiectatic 

 cavities ; when certain intestinal mycoses exist, these sub- 

 stances appear in the urine (cystinuria). 



Of far greater and more comprehensive importance, how- 

 ever, are those metabolic products that are produced in the 

 tissues of the body by the exciting agents of disease, the 

 specific toxins, which give rise to the toxic constitutional 

 manifestations of the infectious diseases. These poisons are 

 generated also by individual bacteria in artificial cultures. 

 Loffier pointed out that by means of glycerin a chemic 

 poison precipitable by alcohol could be extracted from cul- 

 tures of diphtheria-bacilli, and with which the disease could 

 be induced in animals in a manner analogous to that in 

 which it is effected by the bacilli themselves. Roux and 

 Yersin demonstrated that this diphtheria-poison is destroyed 

 by a temperature of 100 .(212 F.). They evaporated the 

 poison-containing bouillon at low temperatures, and ob- 

 tained a residue that was readily soluble in water, and 

 highly toxic. The alcoholic extract proved innocuous. 

 The poison is thus insoluble in alcohol, and is precipitable 

 by this out of watery solution. On dialysis it passed very 

 slowly through animal membrane. Roux and Yersin 

 demonstrated further that the toxin of the filtered bouillon 

 was most completely carried down with a calcium-chlorid 

 precipitate. Attached to this precipitate and dried with it, 

 the toxin proved much more resistant to heat. The poison 

 proved active only when used subcutaneously or intra- 

 venously, while when administered by the mouth, it was 

 harmless. Its action was specific, the palsies characteristic 

 of diphtheria taking place. From the evidence, the French 

 investigators considered the poison a ferment. 



In Germany, Brieger and C. Frankel later studied care- 

 fully the diphtheria-toxin, as well as the toxins of numerous 



