Monthly Microscopical 
200 On the Real Nature JOurEad, Oc 1, 13t0. 
remain for some time in moist cloths without being destroyed. 
When once a room has been infected with such particles, some 
weeks may elapse before the death of all the specific disease-carry- 
ing germs has taken place. 
The pus possessing specific contagious properties cannot be dis- 
tinguished from ordinary pus. It differs indeed from this last, but 
not in appearance, chemical composition, or physical properties. It 
differs in vital power. : 
Vaccine Lymph.—Vaccine lymph which has been just removed 
from the growing vesicle will be found to contain a great number 
of extremely minute particles of bioplasm, which may be well seen 
under a power magnifying from 1000 to 2000 diameters. In 1863 
I made a drawing of the appearances I observed in the bioplasts 
from a drop of perfectly fresh lymph which had been transferred to 
a warm glass slide, and carefully covered with very thin glass, under 
the s'zth object-glass, which magnifies about 1800 diameters. The 
results are represented in the plate accompanying a memoir which 
was published in the ‘Quarterly Journal of Microscopical Science’ 
for April, 1864. 
Tn vaccine lymph which has been kept for some time in glass 
tubes multitudes of very minute particles are observed, and these 
exhibit the most active molecular movements. These particles 
have often been termed débris, and have been regarded as quite 
unimportant elements of the lymph. To them; however, the active 
properties of the lymph are entirely and solely due. And I should 
be no more inclined, in the absence of the most positive evidence to 
the contrary, to regard the fluid portion of the vaccine lymph as the 
active 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 débris, and quite 
unimportant; or to infer that the fluid in which the yeast fungi or 
bacteria were growing was the active agent in exciting fermenta- 
tion, while the actually growing, moving, and multiplying particles 
were perfectly passive. The germinal 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, 
