FERMENTATION 297 



Observations of the highest importance have also been 

 made on splenic fever by Pollender and Brauell. Two 

 years ago, Dr. Burdon Sanderson gave us a very clear 

 account of what was known up to that time of this dis- 

 order. With regard to the permanence of the contagium, 

 it had been proved to hang for years about localities 

 where it had once prevailed; and this seemed to show 

 that the rod -like organisms could not constitute the con- 

 tagium, because their infective power was found to vanish 

 in a few weeks. But other facts established an intimate 

 connection between the organisms and the disease, so that 

 a review of all the facts caused Dr. Sanderson to conclude 

 that the contagium existed in two distinct forms: the one 

 "fugitive 11 and visible as transparent rods; the other per- 

 manent but "latent," and not yet brought within the 

 grasp of the microscope. 



At the time that Dr. Sanderson was writing this re- 

 port, a young Grerman physician named Koch, 1 occupied 

 with tha duties of his profession in an obscure country 

 district, was already at work, applying, during his spare 

 time, various original and ingenious devices to the in- 

 vestigation of splenic fever. He studied the habits of 

 the rod-like organisms, and found the aqueous humor of 

 an ox's eye to be particularly suitable for their nutrition. 

 With a drop of the aqueous humor he mixed the tiniest 

 speck of a liquid containing the rods, placed the drop un- 

 der his microscope, warmed it suitably, and observed the 

 subsequent action. During the first two hours hardly any 

 change was noticeable; but at the end of this time the 

 rods began to lengthen, and the action was so rapid that 



1 This, I believe, was the first reference to the researches of Koch made in 

 this country. 1879. 



