444 CATTLE PLAGUE 



sometimes forms a complete cast of the gut. Peyer's patches and 

 the solitary follicles are swollen and hyperemic. Sometimes the serous 

 membranes, particularly the pericardium and the pleura, likewise 

 show hemorrhages. The liver and spleen are not markedly enlarged, 

 though much congested. In certain localities epizootics have occasion- 

 ally also shown hemorrhages and ulcerations in the buccal and nasal 

 mucosa. 



Immunization. Since it had been noticed that animals which had 

 recovered from the disease were immune, attempts at immunization 

 were early undertaken. The first experiments of this kind were made 

 by Semmer and Nencki. Koch, Kolle and Turner, and Theiler and 

 others have worked out methods of preparing a "Rinderpest" immune 

 serum of high value. This is done in the following manner : Healthy 

 cattle which must particularly be free from piroplasmosis and try- 

 panosomiasis are first immunized by the simultaneous method. On one 

 side of the body they receive 1 c.c. of virulent blood from an animal 

 sick with cattle plague and on the other side a dose of 15 to 55 c.c. of an 

 immune serum. An immune serum of high value is subsequently fur- 

 nished only by those animals which react to this simultaneous injection 

 by fever and otherwise. Races of cattle which show no reaction are 

 unsuitable for the preparation of an immune serum. After an 

 animal which has reacted has recovered it receives an injection of 

 100 c.c. of virulent blood. This is again followed by fever. When 

 the animal has fully recovered it receives 200 c.c. of virulent blood. 

 This method of giving gradually increasing doses is continued until 

 1000 c.c. of virulent blood have been injected at one time. After the 

 last reaction has subsided the animal is bled on three successive days 

 or on three days with an interval of one day between. Each time 

 4500 c.c. are withdrawn. After a short interval the animal can 

 again be injected with a large dose of virulent blood and also be bled 

 again. In -this manner it is possible to obtain large amounts of the 

 immune blood. The latter is allowed to coagulate, the serum is 

 collected and a sufficient quantity of 5 per cent, carbolic acid is added 

 to it so that the mixture contains 0.5 per cent, of carbolic acid. In 

 the preparation of the immune serum it is necessary always to have 

 on hand fresh virulent blood. This is obtained by injecting 0.1 to 

 0.05 c.c. of very virulent blood into unprotected but perfectly healthy 

 cattle. Koch has shown that sheep are also susceptible to cattle 

 plague if inoculated with virulent blood, though they rarely die from 

 the disease, and for this reason they may be used to furnish the 

 virulent blood. The titre, or immunizing value of the immune serum, 

 is determined by injecting non-immunes with 1 c.c. of virulent blood 

 and estimating what quantity of the immune serum will protect 

 against this dose. 



Kolle and Turner have ascertained that a good immune serum will 

 protect cattle for three months against "Rinderpest" in a dose of 100 

 to 200 c.c., and that, particularly in still larger doses, it will save cattle 



