— 499 — 
1. — Feeble schizogonie reproduction in the spleen and elsewhe- 
re, too feeble to prodnee active symptoms, but sulficiently vigo- 
roLis to prevent complété annihilation of the parasites which re¬ 
produce activelv when circumstances are favorable. 
2. — Intracorpuscular conjugation of young parasites resulting 
in a zygote stage or resting body. 
3. — Parthenogenesis, or reproduction by unfertilized macroga- 
metes. 
According to the first theory it was believed tliat so long as the 
parasites remained l^elow a certain level of asexual reproduction 
the disease was latent and when the parasites exceeded in num- 
ber this level a relapse occurred. Sims (i) estimated the greatest 
number of adult parasites which the body can endure without 
symptoms as about two billions. While it is probable that brief 
periods of latencv mav be thus expiained, especially in persons 
possessing a relative immunitv, it is évident that this is not the 
common mode, particularly of relapses at long intervxals, since 
the asexual cvcle is known to wear ont spontfineously after cer¬ 
tain periods. 
Intracorpuscular conjugation, the asexual imion of young pa¬ 
rasites, within the red cell was first observed by Mannaberg and 
in this country bv Ewing. The latter did not attach much impor¬ 
tance to its significance. He says (2) : 
(( A further incpiirv relates to the uniformity with which 
conjugation occurs and its position as an essential or as an acci¬ 
dentai phenomenon in the progress of malarial infection. It 
would seem that a process so fundamental as the conjugation of 
individuals, if it occurs at ail ought to be an invariable feature 
of every active infection but there is not sufficient evidence on 
which to base anv such daim. The four cases referred to as fur- 
nishing numerous clear examples of conjugation were selected on 
account of the abundance of the conjugating forms, but in many 
other cases less numerous though ecpiallv distinct examples were 
seen, indicating that the process is of verv frequent occurrence. 
On the other hand it must be admitted that the majoritv of spé¬ 
cimens from routine cases fail to show anv distinct traces of the 
process ; from which it may be concluded that conjugation is 
probably not an essential feature of the growth of the parasite ». 
Craig (3), who lias probably investigated intra-corpuscular 
conjugation more carefully than anv one else accepts the pro- 
