604 THE STREPTOCOCCI OF MAN 



days and is destroyed in about a fortnight at 15-18 C. A temperature of 

 55 C. for 30 minutes has no effect, but exposure to this temperature for 

 10 hours or to 70 C. for 2 hours totally destroys its properties. 



4. Vaccination. 



(a) With toxin. Attempts to immunize animals by inoculating them with 

 heated cultures (even when cultures heated to 60 C. were used) have given 

 no conclusive results (Marmorek, Schonke witch). 



Marmorek tried to immunize a horse by inoculating it with increasing doses 

 of a toxin which he had prepared (vide ante) and which killed rabbits in doses 

 of 1 c.c. A horse weighing 300 kg. was inoculated with 1260 grams of the 

 toxin in 14 injections carried out over a period of 2 months. There was only 

 a slight reaction and the serum proved to be of very little value. 



(ft) With living cultures. This is the most certain and rapid method of 

 immunization. 



Rabbits. Marmorek immunized rabbits by inoculating them first with old 

 cultures then with increasing doses of virulent cultures. 



The most satisfactory results were secured in those cases in which the animals 

 were in the first instance inoculated beneath the skin of the ear with an organism 

 sufficiently virulent to cause a severe erysipelas : some of the animals succumbed 

 after the first inoculation. But even those animals which were satisfactorily vac- 

 cinated by this method were not immune to the inoculation of the highly virulent 

 passage streptococci of which the lethal dose was 0-000,000,01 c.c. The serum 

 of these rabbits while immunizing other rabbits against infection with the strepto- 

 coccus which had been used for immunization, exhibited as might have been antici- 

 pated no prophylactic properties against a passage streptococcus. 



MironofE had similar results with rabbits treated first with sterilized cultures 

 then with increasing doses of virulent cultures. 



Grromakowski inoculated rabbits in the peritoneal cavity first with an old 

 culture heated to 100 C. then with an old culture unheated (5-10 c.c.) and 

 lastly with increasing doses (1-10 c.c.) of virulent cultures. The animals 

 had fifteen inoculations, a fortnight intervening between each inoculation. 

 In the end the rabbits were immune against an intra-peritoneal inoculation 

 of 30 c.c. of a virulent culture. 



Large animals. Marmorek immunized an ass, an horse and a sheep by 

 inoculating small doses of an extremely virulent streptococcus beneath the 

 skin : as soon as the animal recovered it was re-inoculated with a larger 

 dose. Each inoculation was followed by a marked reaction. 



Horses. Begin with an inoculation of 0*75-2 c.c. of a serum-broth culture of a 

 virulent organism beneath the skin of the neck. (When large quantities of culture 

 are required ascitic fluid or ass serum may be used instead of human blood- serum.) 

 The animal reacts violently ; the temperature reaches 40 C. and this rise is accom- 

 panied by the development of a firm oedema at the site of inoculation. To obtain 

 an efficient serum it is essential that the animals should be made to react violently. 

 When the animal has recovered completely re-inoculate it with a double dose (5 c.c. 

 for example) of a virulent culture. In this way the animal can gradually be brought 

 to tolerate doses of 40 c.c. or more. 



Asses. Asses are much more susceptible than horses and react very violently. 

 In Marmorek' s experience, a dose of 5 eg. of a culture of which the lethal dose for 

 a rabbit is 1 mg. produces a very severe reaction. It is well to begin with less 

 virulent cultures and to increase the doses very slowly. 



[(7) Anti-scarlatinal vaccination. Gabritchewsky relying on the analogy which he says 

 exists between strangles in horses and scarlatina in man proposed to immunize children 

 against the latter with a vaccine. 



[The vaccine consists of a broth culture of a streptococcus isolated from a case of scarlet 



