216 LIFE: ITS NATURE AND ORIGIN 



(1827-1912), which paved the way to modern aseptic surgery. Yet in 

 1863 Pasteur told the Emperor of France that it was his ambition 

 "to arrive at the knowledge of the causes of putrid and contagious 

 diseases." This recalls the remarkable statement of Robert Boyle 

 (1627-1691) that whoever could discover the nature of ferments 

 and fermentation would be more capable than any other of ex- 

 plaining the nature of certain diseases. 



In 1876 Robert Koch (1843-1910), who later discovered the 

 bacteria of tuberculosis, cholera, and other diseases, confirmed the 

 earlier observation (1863) of Devaine that minute rods (bacteridia) 

 exist in the blood of animals dead of anthrax, and are the cause of 

 the disease. Pasteur confirmed Koch's work and convinced those 

 who opposed it. Finally in the spring of 1881 in the farmyard of 

 Pouilly le Fort at Melun (France) came dramatic evidence of the 

 value of immunization: twenty-five sheep protected against 

 anthrax by Pasteur's vaccine survived massive inoculation with 

 these virulent germs, while every one of a like number of unpro- 

 tected sheep died of anthrax. Protection of human beings and of 

 animals against infectious diseases of many kinds is now exten- 

 sively practised, and we have developed an ever-increasing number 

 of substances which will kill or inactivate pathogenic microor- 

 ganisms without too much harm to the patient. 



The struggle to understand the basic causes of diseases has led, 

 in many cases, from the infecting organisms themselves to the in- 

 jurious substances which they produce (exotoxins, e.g., diphtheria) 

 and/or of which they consist (endotoxins, e.g., tuberculosis). Our 

 knowledge of the mechanism whereby definite chemical sub- 

 stances produce definite clinical syndromes is only slowly emerg- 

 ing; but we are here aiming to demonstrate that the lowest effi- 

 cient structural level where the damage becomes determinative of 

 disease is that of biocatalyst structure and activity. "Poisons" may 

 act (1) by massive chemical attack (strong acids or alkalies), which 

 crudely destroy both the catalysts and their protecting milieu; 

 (2) by disintegration of catalyst structures, e.g., by separating 

 carriers and prosthetic groups, or by "lysis" of essential catalyst 

 structures (snake venoms); (3) by coagulation of biocatalysts or of 

 their milieu; (4) by inhibiting the activities of essential biocatalysts 

 (cyanides); and (5) by establishment of new or modified self-repro- 

 ducing biocatalysts under whose influence damage is done to the 

 organism, as in cancer, to be considered below. 



It must be stressed, however, that such catalyst formations or 



