SYNOPSIS xvii 



production by B. rw^er— mycelial development of B. diph.). Tendency to 

 revert does not imply loss of specific character. Variation differs from 

 transmutation in degree alone. 



Transmutation differs from evolution in degree alone. Analogy of 

 different branches of family. Possibility of transmutation. Saprophytic and 

 parasitic pneumococcus. Other examples already discussed (Chap. viii). 

 Experiments suggesting transmutation already discussed (Chap. ix). 1st 

 series, strains not guaranteed pure, results explained by variation. 2nd 

 series, results explained by variation, secondary invasion not excluded. 

 Transmutation improbable. Enzyme theory of disease. (140 — 152) 



CHAPTER XI 



THE ENZYME THEORY OF DISEASE 



Predicates disease not due to bacteria but to their ferments. (1) Ac- 

 quisition and loss of pathogenic powers. (2) Different organisms may cause 

 same type of disease — rabies due to B. diph. (3) Same organism causes 

 different types of disease — in different epidemics {B. injlitenzae) — cases 

 differ in same epidemic — scarlet fever and puei-peral fever — M. catarrhalis 

 infection simulating other diseases, coryza, influenza, scarlet fever, diphtheria, 

 typhoid fever, cerebrospinal fever. (4) Same conditions influence virulence 

 and fermenting power, (a) antiseptics, (&) oxygen — virulence of cholera, 

 toxicity of B. diph., fermenting power of B. dysent., of streptococcus, 

 (c) temperature — optimum temperature — digestive enzyme in cold blooded 

 animals — germ barley — ^marine enzymes — fermenting power of B. coli — 

 virulence of B. diph., B. tetani, B. anthraci*, etc. — enzymes killed at 60° C. 

 and virulence destroyed, {d) sunlight, («) symbiosis — tetanus and pyogenic 

 cocci, B. coli and B. dentrificans. (5) Virulence due to "passage" through 

 an animal and fermenting power due to growth in a sugar, (a) specific, 

 (6) repeated inoculations or subcultures more effective, (c) power readily 

 acquired is easily maintained, {d) if recently lost is quickly regained. 

 (6) Intrar and extra-cellular toxins — ^intra- and extra-cellular enzymes, yeast, 

 digestive enzymes — emulsion of gland or bacteria more potent. (7) Virulence 

 associated with fermenting properties — M. catarrhalis, gonococcus and 

 meningococcus, Hofmann's bacillus and Klebs-LoefBer bacillus, B. coli — both 

 due to adaptation? (8) Living tissues defended by enzymes. (9) Other 

 functions of bacteria due to enzymes — influenced by same conditions as 

 virulence, e.g. pigment formation. (10) These ferments separable from 

 bacteria — enzyme which liquefies gelatin survives bacteria — passes filter — 

 soluble. (11) M. ureae — enzyme separable. (12) Isolation of pathogenic 

 enzymes (pneumococcus). (13) Bacteria deprived of a pathogenic function 

 by environment — same conditions influence ferment activity, {a) ultra violet 

 rays — pathogenesis of B. anthracis, (b) oxygen — power of pneumococcus to 



