ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 385 



the flesli of rabbits, which they soon rendered turbid, all developing 

 the same microbium. The cultures, which were continued up to the 

 tenth, completely retained their purity. After ten or twelve days 

 they always ceased to increase, the exhausted fluid became clear, and 

 the microbia fell to the bottom, forming a yellowish sediment. 

 This sediment consisted entirely of extremely minute granules, 

 which were produced singly or in pairs, groups of from three to 

 ten, or in small irregular masses. During the early days of the 

 culture white spots appeared, resembling the filaments of bacteria, 

 which could be sucked up through a fine tube. They remained for 

 some days in the clear fluid without becoming absorbed, the 

 microbium being at this time enclosed in a somewhat firm mass of 

 mucilage. 



Experimental Tuberculosis.* — D, Brunet records experiments 

 on inoculation with tuberculosis made in 1869 on rabbits. Nine- 

 teen young rabbits were infected, seven with serum from a cancer, 

 six with serum from an ordinary ulcer, and six with tuberculose 

 matter. Of the nineteen, fourteen became tuberculose, the remaining 

 five escaped. Since infection with cancer-serum produced tuber- 

 culosis as often as infection with tuberculose matter, he thought it 

 probable that the infecting mass itself produced no specific action, 

 but that it behaved as a foreign body, causing inflammation around 

 it, and that this gave rise to tuberculosis. Since the matter from 

 ordinary ulcers was more easily absorbed than solid matter, it 

 produced a smaller degree of inflammation, and hence gave rise less 

 often to tuberculosis. 



Etiology of Tubercular Disease.! — The circumstantial evidence 

 that tuberculosis is a chronic infectious disease has been of late years 

 repeatedly insisted on by Cohnheim and others, and the hypothesis 

 that it is due to a specific organism has received considerable support 

 from the discovery of parasitic elements as the materies morhi of some 

 other chronic infectious diseases, such as leprosy. But the organism 

 of tubercle has hitherto eluded research. Its discovery is at last 

 announced by the distinguished worker to whose investigations 

 much of the progress of bacterial pathology has been due, Dr. E. 

 Koch. 



It is only by means of a special method of preparation and ex- 

 amination that the bacteria can be detected. The method consists 

 essentially in a process of colouring the organisms, and their exami- 

 nation under very strong illumination ; but the details of the method 

 have to be varied according to the tissue examined, whether a secretion, 

 blood-tissue fluid, or a section of an organ or tissue. If, for instance, 

 it is desired to demonstrate the presence of the tubercle-bacilli in the 

 fluid of the tissues, a thin layer of this is spread over a cover-glass, it 

 is then dried and warmed for a few moments over a flame, so as to 



* Comptes Kendus, xciii. (1881) pp. 447-8, 



t Verb. Physiol. Gesell. Berlin, 1882, p. 65. Lancet, 1882, pp. e'}5-6. 

 Naturforscher, xv. (1882) pp. 149-50. 



