31 6 BACTERIA. 



duction of small fragments of the spinal cord. This cloud 

 is thrown down at the end of the fourth day, and the pre- 

 cipitate when inoculated into a healthy animal produces a 

 modified form of hydrophobia, modified, however, only in that 

 there is a longer period of incubation than in the ordinary 

 disease. He found on treating a thin film of this fluid, dried 

 on a cover glass, as he had treated the sections of the cord, 

 that small groups of micrococci might be demonstrated, and 

 he concluded that he had cultivated the specific organism. 



Cornil and Babes appear to doubt the accuracy of these 

 observations ; they have never been able to make out any 

 other granules than those which are invariably met with in 

 sections of healthy nerve tissues that have been stained by the 

 Weigert method. Babes, however, claims that he has been 

 able to demonstrate in the brain and in the cord of rabid 

 animals groups of rounded micro-organisms, with a diameter 

 three to four times as great as that of the organism described 

 by Fol ; these are stained in situ by Loffler's alkaline 

 methylene blue solution, which gives them a peculiar rose 

 colour. 



They may be cultivated on blood serum at a temperature 

 of 37° C, on agar-agar, and upon nutrient gelatine made with 

 an extract of the brain of a rabbit. In cultivations the 

 organism grows slowly, appearing as a faint grey spot at the 

 end of several days. The growths spread best in the deeper 

 part of the gelatine. A pure culture of the second or even 

 of the third generation when inoculated into animals occa- 

 sionally produces hydrophobia, but in most cases the cul- 

 tures have no pathogenic properties, and it must therefore 

 be concluded that _the microbe has either lost its virulence, 

 or that it is not the actual cause of the disease. From what 

 has been learned of the causation of other infective diseases 

 it is quite conceivable that there exists in addition to this 

 micrococcus some hitherto undemonstrable element, which 

 along with the organism is capable of producing the disease. 

 For example, in preparations of the brain and of the cord, 

 another microbe is also occasionally met with. This second 

 special micrococcus can only be coloured by using Gram's 

 staining method, and by leaving the sections for a consider- 

 able length of time in the staining reagent. It affects speci- 

 ally the surface of the brain, and is there found in cells 

 which " frequently also contain fatty and proteid granules," 



