332 



SCIENCE. 



[N. S. Vol. XXII. No. 559. 



Dr. Theiler, too, reports that he has suc- 

 ceeded in producing a serum which can be 

 utilized in connection with virulent blood 

 to. confer active immunity. He informs 

 me that his method is a subcutaneous injec- 

 tion of serum and an intra- jugular injec- 

 tion of virus carried out simultaneously. 

 The death rate in mules, from the effect of 

 the inoculation, he states to be about five 

 per cent. It is higher in horses, but he 

 expects shortly to attain the same result in 

 them. During the last horse-sickness sea- 

 son he exposed 200 immunized mules to 

 natural infection in various parts of the 

 country. Of that number only one died 

 with symptoms of horse-sickness. As Dr. 

 Theiler is himself communicating his meth- 

 od in detail to the association, I need not 

 enter more fully into it. 



The man who discovers a practical meth- 

 od of dealing with horse-sickness will be 

 one of the greatest benefactors of this coun- 

 try. There has always been a tradition 

 that a large money reward is awaiting this 

 discovery. I do not know whether this is 

 well founded or not, but certainly such a 

 work would well deserve the highest pos- 

 sible reward. The best reward is to give 

 the successful investigator more oppor- 

 tunity and more assistance in pursuing his 

 beneficent work. The reward given by the 

 French people to Pasteur was the Pasteur 

 Institute ; by the German government to 

 Koch, the Imperial Hygienic Institution. 



Catarrhal Fever of Sheep: Blue Tongue. 

 — This disease was first described by 

 Hutcheon, the chief veterinary surgeon of 

 Cape Colony." It is very similar in many 

 respects to horse-sickness. Both these dis- 



^ It is to Mr. Hutcheon that South Africa owes 

 its knowledge of many stock diseases. For the last 

 twenty-five years he has labored with the utmost 

 earnestness in Cape Colony, often under trying 

 conditions, and his description of the various dis- 

 eases formed the basis of all the modern work done 

 on the subject. 



eases occur most often in low-lying, damp 

 situations, such as river valleys and the 

 coast plain. They also occur at the same 

 time of the year; that is, from January to 

 April. Blue tongue, like horse-sickness, is 

 probably carried from the sick to the 

 healthy by means of some night-feeding 

 insect. At the same time the diseases are 

 not identical, since the inoculation of horse- 

 sickness blood into a sheep does not give 

 rise to blue tongue, nor the blood of the 

 sheep injected into the horse give rise to 

 horse-sickness. 



To Mr. Spreuill, government veterinary 

 surgeon in Cape Colony, acting under the 

 advice of Hutcheon, is due the credit of 

 proving that a preventive serum could be 

 prepared capable of immunizing sheep 

 against this disease. Dr. Theiler informs 

 me he has repeated Mr. Spreuill's experi- 

 ments, and they hope to introduce this 

 method of inoculation at an early date. 



Heart-water of Cattle, Goats and 8heep. 

 — This disease was also first clearly de- 

 scribed by Mr. Hutcheon. It occurs in the 

 Transvaal, Natal and Cape Colony, and is 

 responsible for much of the yearly loss 

 among the cattle, sheep and goats. 



Like the last disease — blue tongue — it 

 resembles horse-sickness in many ways, and, 

 in fact, has been described by Dr. Edington 

 as being identical with it. Like horse-sick- 

 ness, it is a blood disease with an invisible 

 parasite, so that blood injected under the 

 skin of susceptible animals gives rise to the 

 diseJise. One difference between the para- 

 sites of the two diseases is, that whereas 

 that of horse-sickness is contained in the 

 fluid of the blood, that of heart-water is 

 probably restricted to the red blood cor- 

 puscles. The serum separated from the 

 blood is incapable of giving rise to the dis- 

 ease, and the straw-colored pericardial 

 fluid, when injected into susceptible ani- 



