TEXT-BOOK OF BACTERIOLOGY. 259 



is the place at which the disease is first observed. On both sides 

 of the nasal septum and on the nlucous membrane of the turbi- 

 nated bones, diffuse, irregular ulcers with thickened edges are 

 formed. They secrete a thin mucus which runs down the nostrils. 

 Large swellings of the neighboring lymphatic glands follow and 

 extend to the lymphatic vessels, which may be felt through the 

 skin, as thick as one's finger. Here and there a swelling ruptures 

 and deep ulcers form on the skin, and at last the great difficulty of 

 breathing gives a plain indication of the place where the glanders 

 has its special seat in horses, viz., the lungs. 



VII. ASIATIC CHOLERA BACILLUS. 



In the years 1829 and 1837 Europe was visited for the first time 

 by a disease hitherto unknown, which spread from country to coun- 

 try like an irresistible stream, committed the most terrible ravages 

 wherever it came, and seemed destined to become a more terrible 

 scourge to humanity than even the plague had been. The unwel- 

 come guest had come from India, and from this circumstance it 

 was called the "Asiatic " or genuine cholera. 



At longer or shorter intervals this murderous pestilence re- 

 peated its visits, never stopping permanently at any scene of its 

 ravages, but always retiring again from the places it had desolated, 

 and disappearing for years. 



Science sought for the cause and mode of origin of the mysteri- 

 ous disease in vain; opinions and views sprang up in abundance, 

 but none offered a satisfactory explanation. When, therefore, in 

 1883, after a pause of nearly ten years, the epidemic again threat- 

 ened to approach the boundaries of Europe, the different govern- 

 ments, appreciating the gravity of the case, endeavored to unravel 

 the dark secret of cholera and its causes. The German imperial gov- 

 ernment equipped a scientific mission to investigate the origin of the 

 plague and determine its cause. R. Koch was placed in charge of 

 this expedition. After a short time he was able to report, as a result 

 of his investigations in India, that he had found the cause of cholera 

 asiatica in a particular micro-organism, and that he had obtained 

 a pure culture of the germ. 



In all cases of cholera he succeeded in observing in the evacua- 

 tions of the patients and the intestinal contents of the deceased a 

 bacterium perfectly distinct from others by its remarkable form 

 and definite nature. And this fact enabled him to adduce the proof 

 that the new micro-organism appears in no other disease besides 

 cholera, that it must stand in certain relations to it, and that these 

 relations must be regarded as causal. 



