596 
POPULAE SCIENCE EEtlEW. 
entirely due the occurrence of epidemics of small-pox at the 
present day. 
2. Scarlet Fever. — The early history of scarlet fever is 
obscure_, for the disease was long confounded with measles and 
small-pox_, but it is generally supposed that^ like small-pox^ 
it came originally from Africa^ and was imported into Europe 
by the Saracens. It has been known to prevail in Britain 
for the last two centuries ; but although it is only of late years, 
from the reports of the Registrar- General, that we have been 
able to form an accurate idea of the extent of its prevalence, 
there can be no doubt that it has increased greatly during the 
present century, and that it now occupies that pre-eminence 
among the causes of mortality in childhood which was for- 
merly held by small-pox. During* twenty-four years (1838 to 
1861 inclusive) 375,009 of the population of England and Wales, 
and 53,663 of the inhabitants of London, died of scarlet fever, 
or about 1 in every 24 deaths that occurred in England 
during the period in question, was due to this disease. The 
mortality from scarlet fever, in fact, exceeds the mortality from 
small-pox and measles taken together. Scarlet fever is known 
to prevail over the whole of the continents of Europe and 
America, but it is nowhere so common as in Britain. In 
France it is a rarer disease than either measles or small-pox. 
In India it is said never to occur. In most instances it is not 
difficult to trace the occurrence of scarlet fever to contagion ; 
and from the remarkable indestructibility of the poison and 
its tendency to adhere to clothes, furniture, and even to the 
walls of houses, there can be little doubt that the disease has 
a similar origin in many instances, where the mode of trans- 
mission of the poison cannot be traced. How the poison first 
originated is yet a mystery; but there is some probability in 
the view, which has many able advocates, that it originated in 
horses or cattle, and by them was communicated to man. If 
this be so, it is reasonable to hope that investigations as to the 
occurrence of the disease in the lower animals may lead to a 
discovery productive of as great benefits to the human race 
as vaccination. At intervals of a few years, scarlet fever 
spreads as an epidemic; but its ordinary prevalence in this 
country is greater than is generally imagined. The causes of 
these epidemic outbursts are unknown. Many circumscribed 
outbreaks can no doubt be traced to the importation of the 
poison into a population of persons unprotected by a previous 
attack ; but why the poison should be introduced into 
numerous localities at one time, and not at others, is difficult 
to determine. It is tolerably certain, however, that at all times 
the prevalence of the disease is independent of overcrowding, 
bad drainage, or of any appreciable hygienic or meteorological 
conditions. 
