INFECTION OF THE INTERMEDIATE HOST 
173 
Fig. 4. Showing three days of the quotidian clinical attack experienced by Patient 155, infected with P. 
vivax. Periods on which the temperature ranged within normal limits are shown by solid lines, the eleva¬ 
tions on the 1st and 3d days (dotted lines) are due to the multiplication of the same cycle of parasites, 
that occurring on the 2d day (dash line) is due to a second cycle maturing on alternating days. The 
short bar shows the relation of the period of the rigor to each febrile paroxysm. Beneath are shown a 
few representative parasites sketched from blood smears taken at each four hour interval when the 
temperature was observed, grouped according to the relation of their sporulation to the corresponding 
experiences a febrile paroxysm, and will 
experience further paroxysms on subse¬ 
quent days as each further generation ma¬ 
tures. If the infection is dominated by 
but a single generation of P. vivax or P. 
malariae, the paroxysms will recur at ter¬ 
tian or quartan intervals. More commonly 
patients experiencing an initial infection 
with vivax present two generations matur¬ 
ing on alternate days, which will produce 
quotidian paroxysms. It is important to 
note that vivax infections are commonly 
initiated by intermittent quotidian parox¬ 
ysms, even when the patient was inoculated 
on only one occasion. The occurrence of 
two or more cycles or generations thus can¬ 
not be attributed to inoculation on succes¬ 
sive days. In the case of quartan infection, 
a third cycle must arise in order to produce 
quotidian paroxysms. If the time for the 
maturation is either less or more than 24 
hours, it will be noted that the successive 
paroxysms do not recur at the same hour, 
but either regularly anticipate or postpone. 
A clinical attack of either disease char¬ 
acterized by quotidian paroxysms may ab- 
