Medical Officers of the Army of India
from study of this equine " surra"disease : the original observers were distinctly
of opinion that the virus of the disease is represented by the organism, but
hitherto the evidence goes no further than was reached by experiment with
another infective organism—the Spirillum Obermeieri. Thus in my essays of
nearly ten years back I was able to show that the mere presence of the spirillum
did not necessarily entail fever or other marked symptoms of derangement ;
having on five separate occasions of special study detected in the blood this
organism for a period of 24—72 hours prior to the onset of the febrile " relapse."
This I regarded, and do still, as directly adverse to the doctrine that the spirillum
is an epi-phenomenon the result of diseased action ; the argument has been sum-
marised elsewhere, and in this place I need only point out the analogy here
with the hæmatozoon of " surra," which I understand may sometimes be present
early in the horse's blood when no other characteristic symptoms were noted,
and which when transmitted to the dog may, sometimes at least, flourish peri-
odically for weeks without the accompaniment of manifest illness ; the rat, again,
acquires its infection doubtless from a different source and commonly suffers
even less. That data of this kind showing a reduced connection—chronologi.
cal and dynamic—or gradual disconnection between a blood organism and
symptoms of disease, are not necessarily indicative of a primary and fundament-
al separation between the two series of phenomena, has, I think, been fully de-
monstrated for the longest and deepest studied of all the infective diseases ;
and to anthrax I must again refer for analogical evidence bearing on the chief
seeming anomaly found in the monad-blood-infection under review. In that
disease the infective organism is a bacillus which can be isolated and cultivated
apart, there under certain conditions becoming enfeebled as to its virulent pro-
perties, whilst " morphologically the attenuated bacillus differs but little or not
at all from the most virulent bacillus ; the filaments, however, seem a little short-
er and more divided, and culture-aspects less luxuriant also differ slightly—the
spores arising from such culture possess the same modified properties as the
mycelium from which they spring" (Straus. XI me Leçon, l.c., January 1887) :
according, therefore, to this datum, the admission is warrantable that the pro-
tozoic infecting-organism while retaining its morphological aspects may yet,
under conditions, lose some or most of its virulent properties. It is enough, for
my purpose, thus to indicate a possible explanation of the seeming harmless-
ness of the rat-organsim, as compared with the virulence of the equine, which is
yet of indentical aspect. I am indeed aware of the frequent fallacies of ana-
logical inference, but the instance in hand seems unusually free from such risks,
if an opinion can be safely based upon the numerous and direct applications of
the anthrax-data to the facts of the " surra" disease so far as these are known :
the task, however, of demonstrating in detail such applications had best be
deferred until there become available more data regarding " surra " of the precise
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