416 
M. TJttOUESSART 
explains all the facts of the case, and is 'the only one which is not 
driven to uncertain forms of expression and terms of indefinite 
meaning, when seeking to explain the contagious qualities of dis¬ 
eases, as the old medicine did, and as Mr. Jousset de Bellerme 
does, when he speaks of conditions entirely obscure, in referring 
to the production of contagious affections. Terms of this charac¬ 
ter, such as miasma, virus, effluvia, etc., employed in past years to 
designate this unknown essence or entity which constitutes con- 
tagium, could only receive a proper definition by admitting a 
“ catalytic action ,” which had no other use than to postpone the 
solution of the problem, and to displace one unproved hypothesis 
by another.* 
If the parasitic theory has been followed by no other favor¬ 
able effect than the improvement of our medical terminology, by 
displacing these “ miasmas,” “ effluvise,” etc., and especially these 
“ catalytic ” phenomena, an important and gratifying step for¬ 
ward would already have been secured. From the day when it 
was proved that the miasmas and the effluvite, as well as the 
viruses themselves, are nothing more than the germs of the air, 
viz., the microbe and their spores ; from that day the entire do¬ 
main of pathology has been illuminated by a brilliant fact, whose 
value may already be partially comprehended by the progress it 
has accomplished in a period of not more than ten brief years. 
This theory has given us Guerin’s method of closing wounds ; 
the antiseptic dressing of Lister ; the new vaccine of Pasteur— 
and this trio of great discoveries alone, supposing them to be all, 
are more than sufficient to immortalize the germ hypothesis 
And where is the progress that has been accomplished in medi¬ 
cal science by the theories which antagonize the microbian ? We 
know of none—and is not that a sufficient judgment of their 
merits ? 
Again; the microbian theory has passed quite beyond its 
primitive stage, and can no longer be classed in the list of hypo¬ 
thesis. It has fully entered the domain of established facts,and now, 
before a disease can be considered to be due to a specific microbe, 
* See, for instance, the article Miasma in the Dictionary of Nysten, Lithe 
& Robins (Edition 1864.) 
