HISTORICAL. 13 



that all normal healing of wounds and cuts must be preceded by pus-for- 

 mation. A "laudable pus" was recognized, the presence of which was 

 looked upon as a hopeful sign and indicated that repair was proceeding 

 favorably. If the laudable pus which was of a whitish creamy consistency 

 changed to a watery consistency, it was considered an unfavorable sign. 



Mter Schwann and others had demonstrated that fermentation was due 

 to the presence of yeast cells, and it was proven conclusively that decay was 

 caused by bacteria, the relationship of bacteria to disease began to receive 

 consideration. Rayner and Devaine (1850) found bacterial rods in animals 

 suffering from splenic fever. As early as 1840 Heiile, who is by some con- 

 sidered the father of modern bacteriology, made some very valuable deduc- 

 tions regarding the relationship of micro-organisms to disease. He recog- 

 nized a "contagium" (the active cause of the disease associated with micro- 

 organisms), which was supposed to be air-like and yet at the same time 

 fixed. It was supposed to retain its activity for years in the dry state. An 

 unweighable and unmeasurable quantity of this substance may cause an 

 extensive epidemic. Air currents can carry the contagium great distances 

 and cause epidemics in widely separated areas. Bassi (1835) declared that 

 a fungus was the cause of the muscardine disease of silkworms. Pollender 

 (1855) reported that bacteria caused anthrax, verified by Devaine in 1863. 

 Hallier, an enthusiast but not reliable as an investigator, declared that 

 scarlet fever, measles, typhus, and cholera were caused by bacteria. His 

 deductions were, however, not based upon scientific research and proof. 

 Rindfleisch (1866) and Waldeyer (1868) gave considerable attention to 

 wound infection, which, they declared, was due to microbic invasion. In 

 1869 Pasteur demonstrated the microbic cause of the silkworm disease 

 which interfered very seriously with the silk industry in France. Pasteur 

 and Klebs demonstrated experimentally that bacteria could be grown in 

 artificial culture media, and Robert Koch proved that the pathogenic mi- 

 crobes actually secreted the disease-causing substance. This was demon- 

 strated by transferring an infinitely small quantity of the germ material from 

 a diseased organ to a suitable culture medium and making sub-cultures, 

 until the last culture must contain less than the trillionth part of the original 

 substance. Nevertheless, inoculations from the last culture developed the 

 disease with full energy. This experiment was made to meet the assertions 

 that the cause of the disease did not reside in the bacterium, and that the 

 bacterium, if present in the disease, was merely incidental to and not causa- 

 tive of the disorder. 



A heated controversy continued for some time. Such authorities as 

 Liebig, Nageli, Bastian, Cohn, Billroth, Hiller, Schroeder, Hoppe-Seyler, 

 Kiihne, Tiegel, Sanderson, Nencki, Serval, and Paschutin declared that 

 micro-organisms were not the cause of decay, fermentation, and disease; 



