966 The American Naturalist. [November, 
To any mind the only logical term to apply is, experimentally- 
infecting (not disease, but) micro-organism. 
It may be asked why I have not reported upon my experiences 
with this class of germs ? To which I reply, that once I had no 
interest in them, and not until circumstances made it necessary to 
bother with them did I give them any attention. Just at present 
they are having a " cumulative action," to be exploded with an 
intoxicating effect in certain directions when a suitable time 
It is my opinion that the U. S. Government " Swine Plague " 
is one of those cases of " mixed invasion," and I base that asser- 
tion on the fact that those who have tried have utterly failed (ac- 
cording to their published evidence) in sickening or killing a sm- 
gle hog by subcutaneous injection. I utterly ignore results 
following the injection of 8 or 9 ccm. of a bouillon culture di- 
rectly into the lungs of a healthy animal. Just how many varieties 
of germs (absolutely non-specific) would cause pneumonia, and 
even gain entrance to the circulation and find more or less general 
distribution over the organism thus maltreated, can be determined 
by embryo experimenters ; but it can be answered beforehand, 
Just as many as find suitable conditions for continued develop- 
ment in the conditions thus offered. 
Welch himself says that not a single epizootic of his Swine 
Plague has been seen in this country. Then why has he insulted 
common sense and pathological knowledge by speaking of such 
an insignificant and completely undemonstrated complication as a 
new "Swine-Plague?" 
It would be equally justifiable to speak of a large bacillus I 
shall speak of at another time as the cause of certain embolic 
hiEmorrhagic lesions in the kidneys, seen sometimes in Swine- 
Plague, or as a specific or mixed infectious nephritis, because it 
often causes a mechanical-foreign-body-pneumonia for the same 
reason. It is not a specific germ. It does not cause infection. 
It is an invasion. The germ itself is absolutely harmless from 
the infection standpoint. It would be as sensible to speak of 
the filaria broncho-pneumonias in cattle, sheep, or hogs, as in- 
fectious, as those caused by these non-polluting germs. 
