126 



THE AMERICAN MONTHLY 



[July, 



evening* a brief re'sumtfoi the discov- 

 ery, by Dr. Koch, of the micro-organ- 

 isms to which tubercular diseases are 

 due. I will go only so far as may in- 

 terest scientific microscopists, dis- 

 carding all views from a medical 

 stand-point. For thisdiscovery,though 

 at first it seems to be purely of medi- 

 cal interest, is certainly within the 

 realm of the biologist and the field 

 of the microscopist. As long as the 

 origin and the stages of development 

 of bacteria have not been clearly re- 

 cognized, the practical physician does 

 not know when and where and how 

 these enemies of life are to be found 

 or attacked. It is true, in. surgical 

 operations much has been accom- 

 plished, since it has become an ac- 

 knowledged fact that decay in wounds 

 — suppuration and pyaemia — are due 

 to such bacteria. Operations not 

 dreamt of before — such as the cutting 

 out of part of a diseased stomach, oeso- 

 phagus, or pylorus, of a whole kidney, 

 a larynx, a spleen — are undertaken 

 with the chances in favor of success, 

 because we can fight these organisms 

 by sight, as it were. 



We can chase the germs away from 

 the feasts we have provided, that is 

 to say, from open wounds, by anti- 

 septics and disinfectants, and by ex- 

 cluding the air, their vehicle. But 

 those internal diseases which cannot 

 be reached by the knife or by caus- 

 tics, such as diphtheria, scarlet-fever, 

 measles, typhus, and, most of all, 

 tuberculosis, commonly known as 

 " consumption," which alone kills 

 constantly one-seventh of the human 

 race, remain as much a puzzle to the 

 physician as a curse to humanity. 



Some of these micro-organisms are 

 harmless, others obnoxious; we are 

 at their mercy small as they are, great 

 as we think ourselves to be; they pol- 

 lute our air, our food, our drink; they 

 surround us like a host of enemies — 

 neither fire nor sword, neither electro- 

 cautery nor the surgical knife will de- 



*Read before the New York Microscopical 

 Society, June 2d, 1882. 



stroy them. But the discovery which 

 I have the honor to lay before you 

 this evening, and which was effected 

 only by means of the microscope, 

 leads us to hope that we may yet 

 reach them in their original habitat. 



Dr. Rudolph Koch, while practising 

 in the small village of Wollsten, de- 

 voted himself for many years to the 

 study of bacteria, and four years ago 

 published his celebrated critique on 

 Nageli's work " The Lower Fungi, 

 in their Relation to Infectious Dis- 

 eases." He made experiments in the 

 cultivation of Bacillus anthracis (the 

 bacterium of splenic fever), after Pas- 

 teur, and succeeding in this, he made 

 Villemin's experiments with tubercu- 

 lous matter in lower animals. Villemin, 

 ten years ago, pronounced tubercle 

 to be a specific disease, capable 

 of infecting others, and due to a speci- 

 fic virus; but neither Villemin nor 

 Cohnheim, our greatest histological 

 microscopists, both of whom hunted 

 for the specific bacterium was success- 

 ful in the search. 



So recently as the beginning of this 

 year, Cohnheim, in one of his last lec- 

 tures on pathology, said "The direct 

 proof of tuberculous virus is to this day 

 yet an unsolved problem." Cohnheim 

 and Klebs took tuberculous matter 

 in all stages, examined it by different 

 methods, prepared it with different 

 stainings; they found bacteria such 

 as had been found in other diseases, 

 but they did not attain the object of 

 their search — a specific tubercular 

 bacterium. It was reserved for the 

 brilliancy and accuracy of the method 

 of Koch, in his microscopical investi- 

 gations, to bring to light this entity, 

 this poisonous virus, which he recog- 

 nizes as the true cause of those wast- 

 ing diseases known as tuberculosis. 

 I must state here that Koch includes 

 by the term tuberculosis, both scrof- 

 ulous and catarrhal phthisis, and tu- 

 berculous disease of the brain, the in- 

 testines, and other organs. 



The novel feature of his investiga- 

 tion consists first: In the method of 

 staining, combined with the proper 



