Blood examination: 1. Quite numerous large forms, taking up half of the hypertrophic and decolorized red blood corpuscles, and filling the normal ones entirely. 2. Several in the act of sporulation in the form of clusters. Numerous beginning sporulation forms. 3. Isolated, quite small, non pigmented ameboid organisms (very young forms), a further stage of the spores that originated at the beginning of the paroxysm (about 11a. m.), consequently about six hours old.

August 26, 10 a. m. : Temperature, 36°.

Blood examination: 1. Numerous pigmented ameboid organisms, filling one fifth to one fourth of the red blood corpuscle. 2. Isolated large forms containing considerable pigment (sterile forms from the day before).

5 p. m. : Temperature, 36.3°.

Blood examination: 1. Numerous pigmented, endoglobular forms, often strikingly branched, filling one fourth to one half of the blood corpuscle. 2. Isolated large, dropsical forms.

August27, 9 a. m.: Temperature, 37.3°.

Blood examination: 1. Very numerous, large forms, filling entirely or one half of the corpuscle; many of the infected blood corpuscles swollen and decolorized. 2. In isolated large organisms the pigment at rest (beginning sporulation).

At 11 a. m. : Temperature, 39.5°, chill, etc.

From this example it would be easy to construct another for a double tertian, in which the paroxysms took place at the same or different hours of the day.

In illustration of this complicated condition we detail the anamnesis of a case of tertiana duplex, together with its microscopic data.

F. W., aged nineteen, a glass worker, has had paroxysms for the last fourteen days, which, in the beginning, occurred every second day, later daily. Yesterday (August 11) the attack occurred at 11 a. m. ; to day (August 12), at 3 p. m. At 5 p. m., temperature, 39.2°; spleen evidently palpable; pains in the limbs.

Blood examination: 1. Large number of pigmented organisms filling entirely the blood corpuscles. 2. Large number of pigmented parasites in lively ameboid movement, filling half of the corpuscle. Numerous free pigmented spheres; in the blood corpuscles, frequent torn forms (fever forms, see below). 3. Sporulation forms not found.

August 13, 11.15 a. m. : Beginning chill; temperature, 38.2°.

Blood examination: 1. An enormous number of sporulation forms, some regularly, others irregularly, arranged. Number of spores, about 14; in some of them a nucleolus evident. 2. Quite numerous ameboid, slightly pigmented forms, filling about one third of the corpuscle. 3. Several large forms with flagella (one with five flagella). 5 p. m. : Temperature, 37.5°; profuse sweating.

Blood examination: 1. Isolated large forms, some with pigment in motion, others with pigment coagulated, as it were. 2. Numerous lively, slightly pigmented forms, filling one third to two thirds of the red blood corpuscle. 3. Numerous quite small, actively ameboid forms, non pigmented or containing only the finest granules of pigment. 4. Sporulation forms are no longer to be seen, etc.

It is at once evident that we had to do in this case with a double tertian (i. e., false quotidian) clue to two generations of parasites. From the last observation it might appear that three generations were seen, yet on reflection it is clear that the isolated large forms referred to under 1 were only the remains of that generation which caused the paroxysm six hours previously. The organisms from the spores of that generation are represented by the small ameboid forms (No. 3).

It is essential to bear in mind, therefore, other factors besides Golgi's outline, in order properly to appreciate the blood picture. In the first place, in a strict sense, we never see only one generation of parasites. If this were the case,-in other words, if all the parasites which we reckon in general as belonging to the one generation, were exactly the same age to the minute,-all of them would sporulate at the same time and break up at the same time, while, as a matter of fact, the parasites of the same generation vary six to eight hours in age. It is impossible, however, to separate them, because the necessary limits to such a separation are wanting. Still, this separation is not at all necessary, for we need consider only all those parasites which produce a fever paroxysm as belonging to one group or one generation, and whether they are of the same age or manifest differences of hours is not important.

The fact that the individuals of one generation do not sporulate at the same moment, but following one another at short intervals, causes the fever paroxysm to last not a few minutes, but several hours-often even half a day.

This difference in the age of the parasites of one generation naturally produces differences (even though they may not be striking) in size, form, and other characteristics; still it would be wrong to let those influence our conclusions.

Another series of organisms that tend to complicate the blood picture are the "fever forms." These are fragmented parasites which are frequently found free in the plasma, though often, too, in the red blood corpuscles. They are usually round, and several are often attached together. A confusion with sporulation forms is scarcely possible, since they are irregularly pigmented and differ in size.

Flagellate organisms are frequently observed among the tertian parasites soon after the removal of the blood.

[The characters of the sexual forms in the blood are described in the appendix to this article (see p. 123).-Ed.]

The swelling and decolorization of the red blood corpuscles, though very frequent, are not constant. These varying conditions may be seen in Plate V. Bastianelli and Bignami occasionally observed, even in tertian fever, shrunken, brassy looking blood corpuscles (globuli rossi otto nati) similar to those seen in quartan fever. I have never observed these " brassy corpuscles " in tertian fever, although 1 have had the opportunity of studying a great number of cases. They seem, therefore, to be exceptional occurrences.