Malarial Horse-Sickness. 



277 



Since, however, it had been demonstrated that the same virus 

 passed through different donkeys produced different virulence in 

 each case, it seemed advisable to make use of animals which should 

 have, as nearly as possible, the same primary resistance. 



Since, then, " salted " horses are, from the point of view of 

 resistance, somewhat comparable to donkeys of high resistance, it 

 was determined to make use of these animals. 



The procedure adopted was to take a number of " salted " horses, 

 each being capable of resisting very large doses of virulent Horse- 

 sickness blood, to inoculate these with a small dose of virulent blood 

 and to bleed them about the tenth day. 



Blood drawn at this period of time was inoculated in doses of 

 20 cubic centimetres subcutaneously into small batches of clean 

 horses. 



These experiments were not made " en masse," but extended 

 over a long period of time, from the 14th November, 1901, until 

 April of the present year. 



The results are set forth in the Appendix under a Report to the 

 Under Secretar}' for Agriculture, dated April 22, 1902, of which the 

 following is a summary. After the first inoculation, a period of time 

 was permitted to elapse after which a second inoculation was made. 



