SPONTANEOUS GENERATION. 595 
reference to the phenomena of infectious disease, distin- 
guishing arguments based on analogy which, however, are 
terribly strong from those based on actual observation. I 
should have liked to follow up the account I have already 
given* of the truly excellent researches of a young and an 
unknown German physician named Koch, on splenic fever, 
by an account of what Pasteur has recently done with 
reference to the same subject. Here we have before us a 
living contagium of the most deadly power, which we can 
follow from the beginning to the end of its life cycle, f 
We find it in the blood or spleen of a smitten animal in 
the state say of short, motionless rods. When these rods 
are placed in a nutritive liquid on the warm stage of the 
microscope, we soon see them lengthening into filaments 
which lie, in some cases, side by side, forming in others 
graceful loops, or becoming coiled into knots of a com- 
plexity not to be unraveled. We finally see those filaments 
resolving themselves into innumerable spores, each with 
death potentially housed within it, yet not to be distin- 
guished microscopically from the harmless germs of Bacillus 
subtilis, The bacterium of splenic fever is called Bacillus 
anthracis. This formidable organism was shown to me by 
M. Pasteur in Paris last July. His recent investigations 
regarding the part it plays pathologically certainly rank 
among the most remarkable labors of that remarkable 
man. Observer after observer had strayed and fallen 
in this laud of pitfalls, a multitude of opposing conclu- 
sions and mutually destructive theories being the 
result. In association with a younger physiological 
colleague, M. Joubert, Pasteur struck in amid the 
chaos, and soon reduced it to harmony. They proved, 
among other things, that in cases where previous observers 
in France had supposed themselves to be dealing solely 
with splenic fever, another equally virulent factor was 
simultaneously active. Splenic fever was often over- 
mastered by septicaemia, and results due solely to the latter 
had been frequently made the ground of pathological in- 
ferences regarding the character and cause of the former. 
* "Fortnightly Review," November, 1876, see article "Fermenta- 
tion " 
f Dallinger and Drysdale bad previously sbown wbat skill and 
patience can accomplish, by tbeir admirable observations on the life 
history of the monads. 
