THE PROBLEM UE HORSE SICKNESS. Jl 



Laiiiiis collaris {cnuMmm fiskal shrike). 

 Crc.v crc.v ( Iuiroi)ean corn crake). 

 Coliopasscr procnc (long-tailed widow bird). 

 Cicoiiia cicoiiia (white stork). 

 Hrrodias gar::ctta (little egret). 

 Stcphaiiibya coroiiafus (crowned bapwing). 

 Astiir poliicoiiaidcs (a hawk). 

 Scrpciitariits sccrctariits (secretary l)ird). 

 Corz'iis scapnlatits (pied crow). 

 Nicroiiisiis gahar (goshawk). 



And a wild duck, s|)ecies not identified. 



<)f wild mammals the \)\oo(\ of the following s])ecies was 

 injected: — jackal, hedgehog, rock rabbit, bats, striped mice, 

 grev mice, field bats, zebra and yellow meercat. A total number 

 of 67 injections were made. Of reptiles, the bluod of the com- 

 mon iguanas and water tortoises was utilised. A total number 

 of eight injections was made. Of Amphibia, the blood of 

 frogs (a non-determined species) was injected. Twelve injec- 

 tions were made. In addition to these, the blood of domesti- 

 cated ruminants, born and kept on a horse-sickness farm, was 

 injected, via., of cattle, Africander goats, sheep and lambs, and 

 dogs, also blood of salted horses and mules running on the 

 farm ( Onderstepoort) for a number of years. The blood of 

 four natives, who volunteered to a tapping, was also utilised. 



Taking into consideration the difficulty of tracing the reser- 

 voir, the negative results cannot be taken as final. The geo- 

 graphical distribution of both disease and certain animals could 

 give a clue as to the direction in which further experiment 

 should be undertaken. It is known, for instance, that horse- 

 sickness does not occur in ^\>stern Africa from north of 

 Angola as far as North-East Africa, but is present right through 

 Central and East Africa to the shores of the Red Sea. 



4. Im^funtt'^'. 



From a ]:)ractical ]3oint of view, the question of immunity is 

 of great im])ortance. Immunity is only observed in diseases 

 caused by certain groups of micro-organisms, and may be of a 

 shorter or longer duration. The practical side of immunitv is 

 its application for the protection of susceptible animals. It is 

 necessary to ascertain first under what conditions and to what 

 extent immunity is found in horses that have recovered from 

 horse-sickness. 



It is well known that e(|uines can recover from horse- 

 sickness, from either the Dikkoj) or Dunkop form : such horses 

 or mules are known under the term of " salted." 



The mere fact that such salted horses are of greater value, 

 and that a guarantee of '' salting " is asked for by buyers and 

 given by sellers, indicates that such horses are thought to be 



