LIVERPOOL MEDICAL INSTITUTION. 419 
echinococcus which he showed, and which had been bred in the 
duodenum of a dog. 
The fifth meeting of this Section was held on the 28rd April ; 
at which Mr. Newton read a paper “On the Origin and Modes 
of Causation of Infective and Contagious Diseases.’’ After alluding 
to the interest of this subject to microscopists, seeing the micro- 
scope is appealed to by all the parties in this controversy, it was 
pointed out that several distinct modes of causation may be at 
work. One, the result of a specific poison, originated we know 
not how, existing only in consequence of a sort of propagation of 
species by transmission from person to person, and never now 
produced otherwise; as smallpox, scarlet fever, syphilis. A 
second, through poisons produced de novo, dependent on or 
coincident with putrefactive changes in organic matter, either 
animal or vegetable ; as in typhus, typhoid, and puerperal fevers. 
A third may result from some atmospheric condition superadded 
to the preceding, as influenza. But the conditions necessary for 
the spread of one class favour the progress of the others. The 
relative intensity and striking distance of these poisons vary 
greatly, many requiring personal contact, as syphilis, others being 
propagable for some yards through the air only. And even a rag 
which has been applied to the body of the patient may prove a 
carrier, months afterwards, in the case of some diseases. The 
analogy to ferments is very striking, so that Dr. Farr ventured 
to name the whole class zymotics, or ferment diseases. Animated 
particles allied to the yeast-plant have been seen by the micro- 
scope in all putrescent animal fluids. These have received various 
names: Bacterium, Micrococcus, Vibrio, Spirilla, and have been 
supposed to be the cause as well as the mode of transmission of 
all contagious diseases. It appears to have been certainly proved 
that the active agent or ‘‘contagium,” as it is styled by Dr. 
Sanderson, exists, not in solution, but as minute particles. Yet 
this is no proof that the particles are bacteria, or, indeed, living 
matter at all, Besides, it has been shown that all these minute 
forms of life will live and increase in inorganic fluids, not contain- 
ing a trace of animal matter. We may, therefore, infer that 
when bacteria are developed in animal fluids, they derive their 
carbon and nitrogen, not from the albuminous compounds them- 
selves, but from the ultimate products of their disintegration. 
They are then not the cause of disease but among the results or 
accidents of it, and merely associated with a certain stage in the 
putrefactive process. Their presence in great numbers in any 
part or fluid may be taken as an indication of septic change, but 
nothing has yet been done to prove that they have anything to 
do in originating that change, any more than the maggots in 
stinking meat have been the cause of its putrefaction. The 
Bacterium theory of contagion is perseveringly advocated by Dr. 
Sanderson, and others must therefore be set aside. Dr. Lionel 
Beale maintains that all communicable diseases are propagated 
by admission into the body of particles of living matter which 
