The Dilution Method 419 



it becomes one of the most remarkable achievements of 

 medicine. 



Hogyes states that 50,000 persons in danger of developing 

 rabies have received the treatment in the last ten years and 

 that only i per cent, have died. 



The Dilution Method. Hogyes, of Budapest,* believes 

 that Pasteur was mistaken in supposing that the drying was 

 of importance in attenuating the virus, and thinks that 

 dilution is the chief factor. He makes an emulsion of rabbit's 

 medulla (i gram of medulla to 10 c.c. of sterile broth) as a 

 stock solution, to be prepared freshly every day, and uses it 

 for treatment, the first dilution used being i : 10,000; then 

 on succeeding days i : 8000, i : 6000, i : 5000, i : 2000, 

 i : looo, i : 500, i : 250, i : 200, i : 100, and finally the full 

 strength, i : 10. 



Cabot t prepared a stock solution of 8 parts of rabbit's 

 brain and 80 parts of glycerin and water. The quantity 

 of glycerin added comprised one-fifth of the total bulk. 

 After the emulsion was made it was filtered through sterile 

 cheese-cloth. This emulsion containing the glycerin, if 

 kept in the ice-chest, will be of standard virulence during 

 the entire period of- immunization. As the result of his 

 experiments, Cabot found the dilution method attended 

 with danger to the animal immunized, which is not true of 

 the dried-cord method of Pasteur. The latter method is, 

 therefore, the one to be preferred. 



Though the essential cause of rabies has not yet been dis- 

 covered, its lesions can be found in the medulla oblongata 

 and in the spinal ganglia. These consist in certain cellular ag- 

 gregations known as the " tubercles of Babes, "t and in certain 

 degenerative changes in the ganglionic nerve-cells. The regu- 

 larity with which these changes were observed by Babes led 

 him to regard them as useful for diagnosticating the disease, 

 and Van Gehuchten and Nelis and Ravenel and McCarthy 

 have confirmed this opinion. Ravenel and McCarthy || think 

 that Babes gives undue prominence to the rabic tubercle, 

 which consists of an aggregation of embryonal cells about the 



*"Acad. des Sciences de Buda-Pest," Oct. 17, 1897; "Centralbl. f. 

 Bakt. u. Parasitenk.," 1887, n, 579. 



t "Journal of Experimental Medicine," 1899, vol. iv, No. 2. 



t "Virchow's Archives," ex; "Ann. de 1'Inst., Pasteur," 1892, vi. 



"Archiv. de Biologic," 1900, xvi. 



|| "Trans. Phila. Pathological Society," N. S., vol. m, 1900, p. 

 231; "University Medical Magazine," Jan., 1901. 



