ORGANISMS WHICH PRODUCE DISEASE 63 



sweating, etc., prevalent, as the name implies, in the Mediter- 

 ranean area, but also occurring in South Africa, America, India, 

 the Far East, and elsewhere, For many years past, the 

 garrison of Malta, as well as the natives of that island, had 

 been subject to this disease, some 650 of our sailors and soldiers 

 falling ill with it annually. The case-mortality of the disease 

 is low from two to three per cent. but, as each patient had 

 to stay on an average 120 days in hospital, giving roughly 

 a total of some 80,000 days of illness per annum, and as most 

 of the convalescents had to be invalided home, great incon- 

 venience and expense was entailed. In 1 904, a small Investi- 

 gation Commission was sent to Malta by the Royal Society at 

 the request of the Government, and it was discovered that the 

 organism, which had previously been identified as the cause of 

 the disease in the human subject, was harboured by the goats 

 of the island, about 50 per cent being affected, and was 

 communicated to man chiefly in their milk, the organism being 

 found in the milk of 10 per cent, of these animals. This 

 important fact was elucidated by careful research, and especi- 

 ally by the artificial inoculation of animals, and led to goats' 

 milk being eliminated as an article of diet among the garrison. 

 This was at once followed by a drop in the number of cases to 

 a tenth of what they had formerly amounted to, and now the 

 disease is practically stamped out among our soldiers and 

 sailors in the island a triumph of modern scientific methods 

 (see Fig. 15). 



The organism is present in the blood and internal organs, 

 especially the spleen, and is found in the urine and other 

 excretions. It stains, sometimes rather faintly, with the 

 ordinary dyes, and grows easily, though somewhat slowly, on 

 the usual laboratory media, with the production of rounded 

 colonies, more or less translucent and colourless at first, later 

 becoming more opaque and of a yellowish-brown or orange tint. 

 Gelatin is not liquefied. The diagnosis of the disease can be 

 confirmed, not only by obtaining the organism itself from the 

 cases, but also by the agglutination reaction (see p. 49), 

 antibodies in the patient's blood-serum, even when much 

 diluted, causing clumping together of the organism. 



Bacillus pestis. The history of Plague would occupy a 

 large volume. As is well known, epidemics of this disease 

 ravaged Europe in the Middle Ages, Great Britain suffering 

 from it as the Black Death in the fourteenth, and as the 

 Great Plague of London in the seventeenth centuries, numerous 

 lesser epidemics having occurred, some of them, e.g. in Glasgow, 

 Ipswich and elsewhere, within the last few years, but, thanks 



