COLORED PLATE IL—ParaSiteS Of the First Grolip.—Fig. A, 1-22. Phases of development of the ordinary tertian parasite (17 and IS, according to Thayer and Hewetson). 23-29. Hydropie, degenerated, disintegrated bodies. Fig. B. Plan of sporulation of the tertian para site according to Golgi.
2. The tertian parasite requires forty eight hours to complete its cycle of de . velopment. Although this parasite is to I be found in the circulating blood during certain stages of its development, sport" lation takes place chiefly in the spleen and bone-marrow, and in this particular differs from the quartan organism. The young tertian parasite appears in the red blood-corpuscles as a small, pale body, 1 to 2 microns in diameter, possessing ac tive ameeboid motion. Not only are the movements more active than with the quartan parasite, but from the periphery of the tertian parasite long, branching prolongations, or pseudopodia, are sent out and which very soon are again with drawn, to be followed by another change in the shape of the organism. This stage of development may last for twenty-four hours, and then the para site begins to collect pigment-granules and rods, which are finer and of lighter color than in the quartan parasite, and tend to collect particularly around the periphery of the organism. The move ment of the pigment-granules is very active. As the parasite develops, the ac cumulation of pigment increases and the amoeboid movements lessen. Neverthe less these movements do not cease alto gether, for even during the period of the paroxysm marked by apyrexia pigmented parasites may be observed to undergo strange alterations in form by the send ing out of pseudopodia, although by this time more than half of the red blood corpuscle serving as host may have been occupied. (Mannaberg.) The red blood corpuscles infected with the tertian para site undergo decided changes, becoming distinctly swelled, and, when compared with the uninfected corpuscles, are ob served to be much paler than normal. At times, however, the red blood-corpus cles may not increase in size, but may actually shrink and present a brassy or greenish tint.
After the lapse of about forty-eight hours sporulation occurs, having been preceded by the complete quiescence of the parasite and the aggregation of the pigment-granules into a mass near its centre. Just prior to segmentation the parasite attains about the size of the normal red blood-corpuscle, while the swelled corpuscle containing it becomes pale in color.
Segmentation occurs by the splitting up of the parasite into 15 or 20 divisions, or segments, which are not arranged with the regularity characterizing the quar tan parasite. The larger nmnber of
spores contrasted with the smaller num ber resulting frora segmentation of the quartan parasite constitutes an impor tant factor in the differentiation of the two varieties of parasites. The spores of the tertian parasite are round and smaller than those of the quartan parasite, and a refractive dotlet, the nucleolus, which is less defined than in the quartan spores, can usually be observed.
The spores having been set free, fresh blood-corpuscles are entered, and as young parasites the cycle of development is again gone through.
The act of sporulation in tertian, as in quartan, infection corresponds with the occnrrence of the paroxysm, and sev eral hours before this event individual spores may be detected in the blood; they are to be found, however, in great est number at the time of the occurrence of the chill or during the beginning of the hot stage of the paroxysm.
in tertian infection not all the para sites pass through their cycle of devel opment in a typical manner, and the oc currence of flagellate bodies and other degenerated forms, such as vacuolation, fragmentation, etc., is far more coinmon than in the (partial variety.
Infection with two groups of tertian parasites may occur, passing through their cycle of development and attaining -! • —.\ e day,. This k r •. ..11 o. me than infee , n wp. and icsults in . t. f ftNi.r of tillotidian111, I IlOst 110111[1g fevers of • . ..n 1,,nttl. are to be explained by "-. , 4 to tin latk of regularity in +;-•, tour met ,sary for the completion of 41, A.1. of tIolution; thus, the time • on t tav be shorter ot• longer than FL. ,;,i'il..-atitumnal parasite; or L(7 —1. arum of Welch, pre , ra, 1- tuliar difficulties in study for the --.11 that it-, cycle of development is oiread mainly within the internal Its deN elopment is accompanied .'.11 ,rt irr( zularity than that which !,I- at other varieties of parasites. oi I. while. clinically it may be possible t,o milder instances of infection to r etrtain types, such as quotidian o• .1 t,rt'an. the type is so confused as 1,, ri.nder its analysis almost impossible 4.tt.t invt.stigations have not succeeded IT. ,vi,factorily proving that these clin lariatirns depend upon infection ,.ptcial varieties. of testivo-autumnal completin,g. their cycles of de .iot.mr-nt upon different days, and the of ob,prvers have been unable t., c..ccpt the division of the cestivo-att 1. nun] parai-ite into a quotidian and rifty as ur-red by :Nfareltiafava I l',•gnami.