VACCINATION. IMMUNIZATION. INOCULATION 243 



decreases with the continuance of the drying. For example, rabbits develop 

 rabies after 7 days when they are inoculated with material which has been 

 dried 24 to 28 hours; after 8 days, when the material has been dried 3 to 5 

 days; after 15 days, when the drying has continued 6 to 9 days. Animals 

 (horses, dogs) and man are made immune to rabies by injecting them first 

 with a very weak virus, then with a sUghtly more virulent virus, and so on, 

 until at last a very strong virus is injected. After this, the full strength rabies 

 virus can be injected without harm. This method of vaccination has proven 

 of value also as a curative remedy when applied to human individuals bitten 

 by rabid dogs (post-infection vaccination). Other methods of vaccination 

 for rabies (diluted virus, intravenous injection of brain substance, serum 

 inoculation, simultaneous vaccination) have been pubhshed by Hogyes, 

 Helman, Babes, Galtier, Protopopoff, and others. 



Foot-and-mouth Disease. — As early as the beginning of the nineteenth 

 century (Buniva), and very frequently since then, vaccination in the form of 

 emergency vaccination has been effectively employed to induce the regular 

 extension and to shorten the course of foot-and-mouth disease in large herds 

 (Ercolani, Brauell, Renner, Hoffmann, Wirtz, Spinola, Hertwig, Lewes, 

 Brandes and others). Emergency vaccination is a measure entirely worthy 

 of recommendation, because it not only causes a more rapid extension of the 

 disease through a herd and consequently permits an earlier removal of the 

 sanitary poUce regulations, but the vaccination disease frequently runs a 

 milder course and is confined to the mouth. The emergency vaccinations 

 made in the last ten years in numerous herds in almost all sections of Germany 

 have mostly been accompanied by good results; their influence was most 

 favorable when the vaccinations were made at the first appearance of the 

 disease. Of the vaccinated animals, 50 to 80 per cent, became infected on the 

 average; the others proved themselves to be immune. Emergency vaccination 

 is only contraindicated in the malignant form of foot-and-mouth disease, in 

 which the vaccination disease may be dangerous. 



The technique of the vaccination is very simple. The eaiiva of an affected 

 animal is placed in the mouth of the animal to be vaccinated at a point where 

 the mucous membrane has been previously rubbed, or it is inoculated with a 

 lancet anywhere in the skin; impregnated threads can also be drawn under the 

 skin of the ear or tail. Swine are inoculated on the nose with a syringe and 

 needle. Fever occurs 24 hours after the inoculation; on the third day the 

 vesicles appear, and healing of the ulcers begins from the sixth day on. The 

 course of the vaccination disease is in general milder than that of the natural 

 infection. 



With reference to the protective vaccination with blood-serum, the investi- 

 gations are not yet concluded. Hecker's vaccine and "seraphthin," intro- 



