PREFACKH. 
—~ — 
THE number of works which treat of microbes is 
already considerable, but they have all been written 
for a special public of physicians or naturalists, and 
imply that the reader is familiar with the ideas 
already established on pathology or on cryptogamic 
botany. 
Although the science of microbes is of recent 
origin, it has made immense progress in the course of 
a few years. It is, moreover, essentially a French 
science, since it is owing to Pasteur’s admirable 
labours, as well as to his solid genius, aided by the 
faith and energy of his disciples, that this science 
has been able to overcome the prejudices of ages, and 
to penetrate into the very heart of the ancient theory 
of medicine, so as to transform and regenerate it. 
” Every one now speaks of microbes, yet few of those 
who make use of the term have any clear conception 
