September 15, 1905.] 



SCIENCE. 



329 



ease. Since 1903, however, in the Trans- 

 vaal this method has been stopped, and the 

 'serum alone' method introduced. This 

 method is based on the fact that the virus 

 of rinderpest does not retain its infective 

 property outside the body for more than a 

 day or two ; that it dies out in the animal, 

 as a rule, in fourteen days, but in chronic 

 cases only after thirty days, and that, there- 

 fore, the healthy cattle in an affected herd 

 must be protected for this length of time. 

 Now 'serum alone' only protects for about 

 ten days, and therefore the cattle must be 

 inoculated three times at intervals of ten 

 days. The doses of serum must also be 

 large— from 50 e.c. to 200 c.c— so that this 

 method of stamping out rinderpest, al- 

 though quite efficacious, entails a good deal 

 of labor. It is necessary, then, to spare no 

 expense in making the Veterinary Depart- 

 ment efficient, and any cheese-paring legis- 

 lation in this direction may be disastrous. 



II. Horse-sickness. 



The next stock plague I would bring be- 

 fore your notice is horse-sickness. This is 

 a disease which only affects equines — the 

 horse, mule and rarely the donkey. It is a 

 very fatal disease, carrying off thousands 

 of horses every year. It is one of the most 

 important diseases in South Africa, and, if 

 it could be coped with, would enable the 

 Transvaal to become one of the best horse- 

 breeding countries in the world. At pres- 

 ent it is dangerous for any one in Natal 

 and many parts of the Transvaal to possess 

 a valuable horse, the chances of losing it by 

 horse-sickness being so great. 



In 1895, when I went to the north of 

 Zululand with the Ingwavuma expedition, 

 we lost all our horses with this disease. We 

 started with a hundred horses, and had to 

 march back on foot, every horse having 

 died. 



Ten years ago, when I arrived in South 

 Africa, our knowledge of this disease was 



confined to the disease itself; nothing was 

 known as to its causation or prevention. 

 Credit is due to Dr. Edington for having 

 accurately described the lesions and shown 

 its ready inoculability, period of incuba- 

 tion, etc. He, however, fell into the mis- 

 take of attributing its causation to a species 

 of mold fungus. 



Etiology: Geographical Distribution.— 

 Horse-sickness is widely distributed 

 throughout Africa. It is common in 

 Natal, Zululand, the greater part of the 

 Transvaal, Ehodesia, Bechuanaland and 

 Portuguese East Africa. In Cape Colony 

 it occurs in epidemics, with intervals of 

 ten to twenty years. It is undoubtedly a 

 disease which prevails chiefly in low-lying 

 localities and valleys, and is but rarely met 

 with in elevated exposed positions. It, 

 however, is met with now and then in river 

 valleys up to an elevation of some thou- 

 sands of feet. Season has also a remark- 

 able influence on its development, being 

 exceedingly common in summer and disap- 

 pearing on the appearance of the first frosts 

 of winter. 



Ten years ago various theories were held 

 as to the cause of this disease. Some people 

 'thought that it was due to eating poisonous 

 herbs; others, to some peculiarity or state 

 of the night atmosphere; others, to eating 

 grass covered with dew; and still others, 

 to the eating of the spiders' webs which 

 may be seen on the grass in the morning. 

 It was known at that time not to be con- 

 tagious in the ordinary sense of that term ; 

 that is to say, a horse could be stabled 

 alongside a case of horse-sickness without 

 incurring the disease, or a horse might be 

 placed without danger in the same stall in 

 which a horse had recently died of horse- 

 sickness. 



Nature of the Disease. — A horse which 

 has been exposed to infection shows no 

 signs of the disease for about a week. Its 



