ANIMAL INDUSTRY 443 



the Onderstepoort laboratory is outstanding, and the reports of 

 the Director of Veterinary Research, of which eighteen large 

 volumes appeared between the years 1908 and 1932, contain the 

 results of researches carried out at the laboratory. Since 1932 

 these annual reports have been replaced by the Onderstepoort 

 Journal of Veterinary Science and Animal Industry, which is published 

 quarterly and comprises two volumes per year. The basis of tropi- 

 cal veterinary medicine was laid by Sir Arnold Theiler and his 

 co-workers at Onderstepoort, and so important have the results 

 been to the whole continent in leading to direct measures of con- 

 trol and in opening up fields for further research, that a few of 

 them may be outlined. 



Many African diseases are transmitted by ticks, and in the case 

 of several diseases Theiler was the first to analyse the process. 

 Mention should also be made of the brilliant research work of 

 C. P. Lounsbury in the Cape, who determined accurately the 

 transmission of biliary fever of dogs by ticks {Haemaphysalis leachi) 

 and of heartwater by Amblyomma hebraeum. 



The most important of the tick-borne diseases is east coast fever or 

 Piroplasmosis of cattle. At the beginning of this century practically 

 nothing was known about the blood parasites of cattle, and only 

 Texas fever had been described in America and a similar disease 

 found in Europe and other countries. Then east coast fever was 

 recognized as a separate disease, and the parasite, Theileria parva, 

 was discovered by Theiler in 1904. In 1906 Theiler discovered 

 another parasite, Theileria mutans, very similar to T. parva in the 

 blood of cattle. This was one of the parasites which was held 

 responsible for the so-called 'gallsickness' of cattle in South Africa, 

 but in 1 910 Theiler found that another parasite, Anaplasma mar- 

 ginale, was the real cause of this disease. A variety of this parasite, 

 A. centrale, was found to produce a mild form of the disease and 

 to be an excellent immunizing agent. 



At Onderstepoort also it was discovered by Gowdry that heart- 

 water was caused by a Rickettsia. Blue-tongue in sheep was found 

 by Theiler to be due to a filterable virus, which was subsequently 

 attenuated and a very reliable vaccine placed on the market. 

 Horsesickness was similarly elucidated and methods of prevention 

 have recently been adopted by preparing a neurotropic mouse- 



