114 CHEMISTRY OF BACTERIA AND THEIR PRODUCTS 



used the products of autolysis of cholera vibrios successfully in 

 the production of immunity, and states that the products of 

 autolysis consist largely of nucleins. 



It is probable that in every culture bacteria are constantly 

 being destroyed, either by their own enzymes or by the proteo- 

 lytic enzymes of the other bacteria. Some bacteria are much 

 more rapidly autolyzed than others, cholera vibrios, colon, 

 typhoid, and dysentery bacilli being rapidly digested, while 

 tubercle bacilli are very little and slowly autolyzed. Conradi l 

 who has shown that certain products of autolysis of tissues are 

 bactericidal, believes that also in cultures powerfully bacteri- 

 cidal substances are produced through autolysis of the bacteria. 

 This, he thinks, accounts for the decrease in numbers of living 

 bacteria that always sets in after a short period of growth on 

 artificial media ; for example, the bacteria in a culture of cholera 

 vibrios increase in number for about twelve hours, and then their 

 number steadily decreases. When cultures that have ceased to 

 grow are placed in a diffusion membrane, so that the autolytic 

 products can escape, growth promptly begins again. 2 It has 

 been found by Turro 4 that extracts from various tissues con- 

 taining autolytic enzymes can digest bacterial cells. 4 It is very 

 possible that the endotoxins contained within such pathogenic 

 bacteria as typhoid and cholera are liberated through digestion 

 of the bacteria, either by autolysis or by the enzymes of the 

 leucocytes and tissues of the organism that they have infected. 

 These, and a number of other bacteria, produce no soluble 

 toxins that diffuse from the cells, as do diphtheria and tetanus 

 toxin, and it is difficult to explain the toxic effects these bacteria 

 produce without assuming that their intracellular toxins are 

 liberated in some such way. It is also quite probable that the 

 enzymes found in filtrates from bacterial cultures are liberated 

 from the bacterial cells only when these have been autolyzed. 5 

 With the possible exception just mentioned, there is little evi- 

 dence that the bacterial enzymes play any important r6le in 

 infectious diseases. They may be a slight factor in the diges- 



1 Munch, raed. Wochenschr., 1905 (52), 1761. 



2 The conclusions of Conradi are contested by Manteufel, Berl. klin. Woch., 

 1906 (43), 313. 



3 Cent. f. Bakt., 1902 (32), 105. 



4 Sigwart (Arb. a. d. Path. Inst. Tubingen, 1902 (3), 277) found that tryp- 

 sin and pepsin (without acid) do not injure living anthrax bacilli. 



5 Emmerich and Loew (Zeitschr. f. Hyg., 1899 (31), 1), having found that 

 pyocyanase is capable of destroying and digesting other bacteria than pyocy- 

 aneus, suggested that it might be a potent factor in producing artificial immu- 

 nity. Their rather remarkable hypotheses have been much contested, and are 

 of questionable value. (See Petrie, Jour, of Pathol. and Bacteriol., 1903 (8), 

 200 ; also, Kettger (Jour. Infectious Diseases, 1905 (2), 562). 



