INFECTION IN INTERMEDIATE HOST: QUARTAN 
193 
stant postponement of one cycle (A) results, it occurring 24 hours late at the end of a thirteen-day 
period. 
On the other hand, we know little regard¬ 
ing immunity in P. malariae infections. 
If one classifies the three cycles as Boyd 
(1940b) did (cycle “ A” whose paroxysms 
occur 1st, 4th, 7th, etc., days following in¬ 
oculation, cycle “B” whose paroxysms fall 
on the 2d, 5th, 8th, etc., days, and cycle 
“C” with paroxysms on the 3d, 6th, etc., 
days), it is evident that a patient could 
exhibit one or more of seven possible single 
and multiple arrangements of cycles (A, 
B, C, AB, AC, BC, or ABC) during the 
course of his attack. Examining the par¬ 
oxysms from this standpoint, it was noted 
that (a) cycle “A” was never seen where 
an artificially inoculated patient experi¬ 
enced a simple quartan course throughout, 
(b) twenty-seven patients, artificially in¬ 
oculated, exhibited 5 or more of the possible 
7 combinations and five patients experi¬ 
enced all seven, (e) naturally inoculated 
patients tend to a simpler pattern of cycle 
combinations, (d) one-half of the arti¬ 
ficially induced attacks were initiated by 
“C” cycle and 37 per cent terminated on 
the “A” cycle, (e) naturally induced at¬ 
tacks were most frequently initiated by 
“A” cycle, (f) the paroxysms, following 
either the natural or artificial method of 
inoculation tend to show progressive (C to 
BC to B to AB to A etc.) rather than 
regressive (C to CA to A to AB to B to BC 
etc.) changes in the cycle alterations. In 
naturally inoculated patients the cycle in¬ 
tervals are relatively more stable and the 
“A” cycle is most prominent. This may 
be significant inasmuch as in artificially 
induced infections there is a marked tend¬ 
ency to work around to the “A” cycle 
before the termination of clinical activity. 
In addition to the above alternations, 
there also occurs a true anticipation or 
postponement (Fig. 4, No. B-2824) of 
paroxysms. Successive paroxysms may 
consistently anticipate the preceding One 
of the same cycle by several hours until 
