THE BIOLOGY OF DAILY LIFE. 37 



" Koch was able to cultivate these bacteria 

 on gelatinized meat infusion, or solidified blood 

 serum, where they grew in large quantities. . . . 

 The minutest quantity of these bacteria, culti- 

 vated in this way, and inoculated into an 

 animal, produced the original disease in its full 

 virulence. 



"Such experiments prove absolutely that 

 the bacteria growing in the blood were the 

 real cause of the disease. In a number of 

 instances similar proof that bacteria are the 

 cause of disease has been furnished, such as 

 splenic fever, septicaemia in mice, chicken 

 cholera, septicaemia in rabbits, malignant 

 oedema in guinea-pigs, and tuberculosis in the 

 lower animals." * 



Whatever we may think of the reasoning, the state- 

 ment is clear and bold enough "Bacteria came 



But if from this we turn to a work intended for 

 actual workers, and by a writer of high authority, as 

 an experimenter, we find a very different tone. Very 

 serious doubt is thrown upon the causative power of 

 these microbes, and the exclusive influence they are 

 assumed to have in specific disease is positively denied 

 in nearly all the instances mentioned above. f I give 

 a few quotations from the latest edition of Dr. Klein's 

 u Micro-Organisms and Disease" a work which may 

 be regarded as the standard work on this subject, in 



* " National Encyclopedia," latest edition. 



t " Micro-Organisms and Disease,'* by E. Klein, M.D., joint 

 lecturer on General Anatomy and Physiology at St. Bartholo- 

 mew's Hospital. 



