THE ETIOLOGY OF BLACKLEG, ETC. 
313 
evaporates, and spreads in the atmosphere in the form of 
effluvia in emanations less watery but as deleterious as that 
of ponds.” 
4. Influence of Food. —After reviewing the various opinions 
entertained on this subject, which have been ascribed as 
principal causes, as—forage damaged by mildew, wet, frost, 
by the heat of the sun, and slimy deposit of inundations, the 
cryptogamic theory, &c., they resume thus :—“We think it 
is not demonstrated in the present state of science that food 
composed exclusively of damaged materials gives rise to 
charbon, exclusive of the conditions under which the disease 
generally occurs.” 
M. Reynault and Reynal conclude their observations on 
the etiology of charbon by the following general propo¬ 
sition :— 44 That the causes of charbonic diseases are due to 
*/ 
the emanations disengaged from the soil during the heat of 
summer , and to the various modifications undergone by plants 
under this influence .” 
M. J. Cruzel, a well-known French cattle pathologist, and 
author of a very practical work on the diseases of the ox, 
perfectly agrees with the article I have just quoted, and in a 
note in his work says, 44 The most complete work which has 
been published on the charbonic diseases is that of Renault 
and Reynal, and I think I cannot do better than take the 
greater part I have to say from it.” ( 4 Traite Pratique de 
Maladies l’espece Bovine,’ p. 577, 1869.) 
Tundel, in one of his 44 Veterinary Chronicles of Germany” 
(‘ Recueil de Med. Yet.,’ May and June, 1871), discusses 
the etiology of charbon, and supports himself on the authority 
of the German authors. The gist of his remarks is included 
in the following quotation : 
44 Charbon is always due to an infection, to an active agent, 
which appears to be of cryptogamic nature, acting on the 
blood in the form of a septic ferment. This agent is a 
miasma that the animal finds about him ; that is say, an 
organic substance, a debris of vegetable matter suspended in 
the air, and retained there by watery vapour; sometimes 
this miasma is found in the water, more rarely mixed with 
the solid bodies serving as food. It is in the miasma that 
we always find the cause of the spontaneous eruption of 
charbon , an expression slightly incorrect, but which I think 
I ought to preserve. The disease may proceed from infected 
animals ; the miasma, the infecting agent, is multiplied then 
oftener after the fashion of a virus, and is communicated by 
fixed and volatile contagion. 
44 This infectious origin of the charbonic diseases, of vege- 
