Description of the Illustrations.

PLATE IV.

FIGURES 1 AND 2. Spirillum of the rat x 800 diameters: Temperature of the rat
101.6° F.

FIG. 1.—Fresh blood on watching; temperature of the rat 103°F. " The organisms
have the aspect of veritable spirilla, moving actively amongst the fibrine
bands and in clear serum spaces, yet not easily seen even with the 1/10
inch immersion." (Extract from Note-book. ) A white corpuscle is shown
to the right above; below at * are some dried and stained organisms
showing a tendency to divide, and one with a central dark spot.

" 2.—Blood after 20 hours, inclosed in sealed cell. " In open spaces are seen
2—4 spirilla in active constant movement (chiefly rotation), quite dis-
tinct from the languid and intermittent movement of the bacteria
which are also present" (from Note-book ) (a ) Micrococci, (b ) Bacillar
rods, (c ) The spirillar organisms.

CHART NO. 1.—Bi-daily observations of temperature and blood-state of the rat
showing the above spirillar contamination. Memo. —When spirillar
organisms "doubtfully seen," then other minute bodies detected,
often having the aspect of such organisms either immature or else
disintegrating.

" NO. 2.—A sample of ordinary temperature ranges in a rat having healthy-look-
ing blood.

" NO. 3.—A sample of temperature range in a newly-captured rat having on the
first three days monads in the blood, and subsequently suffering from
swelling of the feet and paraplegic symptoms.

" NO. 4.—The entire temperature and blood data of the experimental monkey, into
whose blood the rat's monads had found their way after intra-peri-
toneal injection. Day 1, is the evening of experiment; on day 2, there
are two positive observations, and two also on day 3, after which no more
monads visible. The "uneasiness " of the monkey on the first 3 or 4
days was not more than accountable by the mild irritation of puncture,
and the temperature-range seemed hardly disturbed.