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when carefully watched; the plasma constituting the thicker portion of their substance may be seen
suddenly to swell out at certain places, sometimes so as to divide the body into two parts. At other
times two or three such constrictions and dilatations may be detected, the dilatations being possibly
observable only on one side, at other times they assume an arrow-shaped aspect. Occasionally something
like granularity may be observed before their disappearance, but not a trace of them is left after their
disintegration : it seems as though they had been dissolved in the serum in which they were found.
The width of the anterior half or body portion averages .008 to .001 m.m. and its length from .020 to
.030 m.m. or an average of .025 m.m. The flagellum, so much of it as is visible, is somewhat of the same
length, so that the total length of the organism equals about .050 m.m. or 1/500". The last, however, may
be considerably longer than this, as the slope from the body portion is very gradual, and when the eye
follows it to the bounds of visibility, an impression is conveyed that there may be still more of it,
beyond the power of either Ross 1/12" or Powell and Lealand's 1/16" to reveal.
Wittich* described similar organisms in the blood of badgers in Germany.
Wittich's observations coincided with Lewis' as regards their being found in the blood of apparently
perfectly healthy animals, though Koch† found that the hamsters which he procured died, one within
two days of being in captivity, and four others subsequently. It does not appear that the blood of these
hamsters was examined during life, but after death it was found, in each case, to contain the organism
in question. No reference is made to the examination of other hamsters, so that it is not quite clear
whether the animals died as a result of captivity or in consequence of the parasitism. Both Wittich
and Koch suggest that the parasites found by them in the blood of hamsters are in all probability iden¬
tical with those found by Lewis in India.
‡ Crookshank in 1886 examined the blood of a few white rats for hæmatozoa but without success,
and then proceeded to obtain a large number of brown rats from the London sewers, and ascertained
that the blood of no less than 25 per cent. of these apparently healthy animals contained these active
organisms. After careful observations of the organisms, Crookshank came to the following conclusions :—
"They are polymorphic, presenting for the most part slightly tapering bodies which terminate at
one end in a stiff, immobile, acutely-pointed flexible filament or spine-like process, and at the opposite
end are provided with a long flagellum, which longitudinally attached a delicate undulating fin-like
membrane can be traced, which starts from the base of the posterior filament, and becomes directly
continuous with the flagellum. The body is found to be distinctly granular, with one or more highly
refractive spherules. When the rapid movement is arrested the undulating membrane is distinctly
visible. The organism moves in the direction of the flagellum, the flagellum threading its way between
the corpuscles and drawing the rest of the organism after it."
Carter's§ observations on rats were chiefly of the species Mus decumanus and Mus rattus, the
small brown or grey rat being oftenest infected. A few examples examined of Mus bandicottus and of
Sorex species (also of mice) gave negative results. Males were the most numerous; in pregnant females
the fœtus was not implicated: the animals were active, non-febrile, and bearing injuries incidental to
capture, all seemed alike healthy, so that one could not surely guess beforehand the state of their blood.
Animals fed upon wheaten bread, rice and water ad libitum. The temperature was taken twice or thrice
daily per rectum, and usually in control-animals as well as those under experiment. From 99° F.
A.M. to 101°F. P.M. (37.3°—38.4° C.) seemed to be the common range under conditions stated, but
degrees somewhat higher and lower were occasionally noted attributable perhaps to excitement or
exhaustion.
Of 60 rats caught in February, 9 (15 per cent.) showed the Trichomonas. Of 150 rats caught in
August to December, 16 (10 per cent.) were found infected. Inclusive proportion showing the hæma¬
tozoon, nearly 12 per cent., which is less than one-half of the percentage found in Calcutta and London.
There was no pronounced or constant differences in the rectal temperature of infected rats as com¬
pared with the non-infected. No striking corresponding change of temperature was ever noted when it
happened that the monads disappeared suddenly from the blood.
A common lesion amongst animals kept was atrophy and necrosis of the tail, then usually the feet
became swollen and finally there were signs of paralysis.
Fifteen special autopsies were made, of which nine of rats showing the hæmatozoon, and in none of
them did I see any peculiar coarse lesion of the blood or vicera or tissues of the trunk. Microscopically,
the only change noted was an increase of leucocytes ; the spleen elements seemed normal. As seen in
the freshest blood their movements are so rapid as to be followed with difficulty by the eye, certain
optical impediments concurring thereto; yet, evidently, the chief one is that of progression more or less
direct, and accompanied by a lateral lashing or sometimes an apparent rotation. Progression may doubt-
less be either backward or forward and misled by the idea of the thicker end being the head of the
* Wittich.—Spirillen im Blut von Hamstern. Centralblt-f-Med. Wiss 1881. No. 4.
† Koch.—Mitteilungen ans der Kaiserlich Gesundheitsamte Vol. I, 1881, p. 9.
‡ Crookshank, E. M., M.B.—Flagellated protozoa, &c. Journal of the Microscopical Society, 1886.
§ H. Vandyke-Carter, M.D., "On the lately demonstrated blood contamination and infective disease of the Rat and Equines
in India." Scientific Memoirs by Medical Officers of the Army of India, Vol. IV, 1887.