312 
THE ETIOLOGY OF BLACKLEG, ETC. 
Synopsis of MM. Renault and ReynaVs Chapter on the 
Etiology of Charbon. 
The history of the outbreaks of charbon in France, which 
have been enumerated above, shows the influence of the tem¬ 
perature. Renault and Reynal discuss the causes under four 
different heads, as follows :—1. Influence of the temperature. 
2. Influence of ponds and marshes. 3. Influence of the soil. 
4. Influence of food. 
In treating of the first influence, they say it has been 
observed to coincide in its appearance with humidity and 
persistent fogs (Goud). Humid, warm air, temperature 
stormy, alternations of burning heat and storms (Ver- 
heyen). The history of its enzootics shows that for centuries 
it has appeared in years where a very hot season succeeds 
without much transition to a very wet one. The years 1712, 
1731, 1775, 1779, 1780, 1823, 1824, 1825, 1846, furnish 
but too memorable examples. 
2. Influence of Ponds and Marshes. —After reviewing the 
marshy parts of France in which the disease is common, they 
say this fact is remarked, not only in France, but in various 
countries of Europe. It is enzootic in the marshy countries 
of Esthonia, Livonia, and Courland (Verheyen). In Po¬ 
land (according to Verheyen) and Germany and Hungary 
charbon appears each year, attacking chiefly beasts in inun¬ 
dated pastures on marshy localities. In Spain it is enzootic 
in the submerged valleys and sea coasts of Catalonia (Es¬ 
cobar). In Corsica, especially the southern side, which is 
intersected with marshes and stagnant waters, the herdsmen 
emigrate with their flocks and herds to the mountains at the 
commencement of the hot weather, knowing by experience, 
if they did not do so, charbon would attack nearly the whole 
of the animals. In Siberia, which is covered with innu¬ 
merable lakes and marshes, the beasts are each year deci¬ 
mated by the jaswa, or charbonic fever, which in 1784 killed 
100,000 horses (‘Ann. de Med. Vet., 5 1854). 
3. Influence of the Soil. —Charbon has been observed to 
more particularly take place in districts where the earth has 
a clay, calcareous schist, and calcareous clay base. It occurs 
but exceptionally on siliceous or granitic soils. M. Rivierre 
thus explains the fact :—“ The arable layer, of slight thick¬ 
ness, easily allows the rain to penetrate it; this arrives at 
the compact clay and is stopped, forming a sort of internal 
marsh. This water, like that in the vegetable soils, holds in 
solution or suspension a quantity of animal and vegetable 
ddbris, which by the action of heat decomposes, ferments. 
