324 
NATURE OF MATERIES MORBI. 
respect, from ordinary animal bodies. They are probably 
complex organic products, possessing a quaternary arrange¬ 
ment of elements, like the generality of animal matters. 
Their morbid power resides in their peculiar dynamic con¬ 
dition, which is capable of maintaining itself so long as no 
elementary change occurs to alter their state. In this respect 
these substances, in their intimate nature, may justly be 
compared with those poisonous products which, under cer¬ 
tain circumstances, are developed in some kinds of sausages, 
and occasionally in the human body after death. As it has 
been found impossible to extract any special virus from such 
putrid substances, so it is easy to understand why we are 
unable to recognise any tangibly poisonous material in the 
emanations of persons struck down by contagious diseases. 
In both cases every known method of investigation has 
failed to reveal any peculiar morbid compound, and the pre¬ 
sence of the morbific force is only rendered cognizable to 
the senses by the train of symptoms excited in the system 
of those brought within its influence, which will be more or 
less felt according to the greater or less degree of intensity 
of the state of metamorphosis in which the poison happens 
to be at the moment of its reception, the nature of the 
medium through which it finds admission to the living body, 
and the presence in the system of materials capable of 
entering into the same state.* The facility with which 
those matters communicate their peculiar condition to the 
blood of individuals predisposed to receive such impressions 
may be easily comprehended by calling to mind the ex¬ 
tremely complex nature of the circulating fluid, its constant 
state of transformation, the manner in which it is dispersed 
throughout the entire body and permeates every tissue from 
the lungs and bowels within to the skin without, and, above 
all, the circumstance that such morbific matters are them¬ 
selves blood products, and consequently composed of con¬ 
stituents most favorably circumstanced for the diffusion of 
their peculiar state of mobility in the circulating mass. 
It is a law of catalytic metamorphosis, that a body in the 
act of decomposing, on being added to a fluid in which its 
own constituents are present, is itself reproduced, exactly as 
new yeast is formed by the addition of that substance to 
saccharine liquids containing gluten, and that the only 
limits to this process of reproduction are the amount of 
matter present which is capable of‘undergoing such altera¬ 
tion, or the supervention of some counteracting influence. 
* Dr. Budd, of Clifton, on “ The Propagation of Typhoid Bever 
‘ Lancet,’ Dec. 12, 1856. 
