ON THE REAL NATURE OF DISEASE GERMS. 857 
material, than I should be to assume that the fluid in which 
the spermatozoa 'were suspended was the fertilizing agent, and 
that the spermatozoa themselves were merely epithelial debris , 
and quite unimportant ; or to infer that the fluid in which 
the yeast fungi or bacteria were growing was the active agent 
in exciting fermentation, while the actually growing, moving, 
and multiplying particles were perfectly passive. The ger- 
minal particles in all cases are, without doubt, the active 
agents, and it seems to me as much opposed to the facts of 
the case to maintain that the materies morbi of cattle plague 
and other contagious fevers is a material that can be dissolved 
in fluid, and precipitated and re-formed, or sublimed as a 
volatile substance, as it would be to look upon any living 
organism as the result of the concentration of an albuminous 
solution, and capable of resolution and precipitation. 
The little particles I have represented in my drawings 
could not be distinguished from the minute particles of 
living pus, or other germs of living germinal matter, and I 
think they consist of a peculiar kind of living matter, the 
smallest particle of which, when supplied with its proper 
pabulum, will grow and multiply, giving rise to millions of 
little particles like itself, each having similar properties and 
powers. 
I consider it to be almost certain that the material of w r hich 
these particles are composed has the power of forming matter 
like itself from pabulum around it, which differs from it in 
properties and composition. Such living germs may pass 
from the organism on which they grew to another, and will 
grow and multiply there if they meet with the proper pabulum. 
The only condition in which matter is known to exhibit these 
powers of self-multiplication is the living state. 
M. Chauveau* described these same bodies in 1868. It 
is evident he had not seen my observations, published in the 
Cattle-Plague Report, or my previous researches published 
in the Microscopical Transactions for 1863.f Chauveau 
showed that the active particles subsided after forty-eight 
hours, and that no effects were produced by inoculating the 
albuminous supernatant fluid, while the full effects w^ere pro- 
duced by vaccinating with the deposit. As would be sup- 
posed from the excessive minuteness of these bodies, they 
are not to be separated by ordinary filtration, but if the fluid 
containing them also contains a trace of coagulable fibrin 
* ‘ Comptes Rendus/ February, 1868. 
f “Beale had, before Chauveau, declared that the ‘active properties of 
vaccine lymph are entirely and solely due’ to these corpuscles. He has 
figured them.” — Dr. Farr, ‘Report on the Cholera Epidemic of 1866, 
p. lxviii. 
