552 FRAGMENTS OF SCIENCE. 
are others smitten with everlasting incompetence in regard 
to such interpretation. To the former class in an eminent 
degree belonged the illustrious philosopher Robert Boyle, 
whose words in relation to this subject have in them 'the 
forecast of prophecy. "And let me add," writes Boyle in 
his "Essay on the Pathological Part of Physik," " that he 
that thoroughly understands the nature of ferments and 
fermentations shall probably be much better able than he 
that ignores them, to give a fair account of divers phe- 
nomena of several diseases (as well fevers as others), which 
will perhaps be never properly understood without an 
of ferine 
insight into the doctrine of fermentations." 
Two hundred years have passed since these pregnant 
words were written, arid it is only in this our day that men 
are beginning to fully realize their truth. In the domain 
of surgery the justice of Boyle's surmise has bean most 
strictly demonstrated. But we now pass the bounds of 
surgery proper, and enter the domain of epidemic disease, 
including those fevers so sagaciously referred to by Boyle. 
The most striking analogy between ncontagium and a 
ferment is to be found in the power of indefinite self- 
multiplication possessed and exercised by both. You 
know the exquisitely truthful figures regarding leaven em- 
ployed in the New Testament. A particle hid in three 
measures of meal leavens it all. A little leaven leaveneth 
the whole lump. In a similar manner, a particle of 
contagium spreads through the human body and may be so 
multiplied as to strike down whole populations. Consider 
the effect produced upon the system by a microscopic 
quantity of the virus of small-pox. That virus is, to all 
intents and purposes, a seed. It is sown as yeast is sown, 
it grows and multiplies as yeast grows and multiplies, and 
it always reproduces itselL To Pasteur we are indebted 
for a series of masterly researches, wherein he exposes the 
looseness and general baselessness of prevalent notions 
regarding the transmutation of one ferment into another. 
He guards himself against saying it is impossible. The 
true investigator is sparing in the use of this word, though 
the use of it is unsparingly, ascribed to him; but, as a 
matter of fact, Pasteur has never been able to effect the 
alleged transmutation, while he has been always able to 
point out the open doorways through which the aftirmers 
