PROPHYLAXIS OF MALARIA. 
99 
as gamete-carriers and kept in hospital until, by 
the administration of quinine, the number is reduced below this mini¬ 
mum. d he number of gametes present is easily ascertained by com¬ 
paring the number with the number of leucocytes counted in a stained 
smear, properly prepared, and while there may be numerous theo¬ 
retical objections to this method of estimating the number actually 
present, I believe that the rule is a safe one to follow in prophylactic 
work, and that if it were faithfully followed it would result in a 
great reduction in the amount of malaria in any locality. 
The effect of quinine upon the gametes. —No morphological changes 
have been noted by myself in fully developed gametes of any of the 
species of malarial plasmodia after the administration of quinine, 
and the observations of Marchiafava, Gualdi, Martirano, Darling, 
and others, have shown that these forms are capable of development 
in the mosquito, even though this drug has been administered for 
weeks in large doses. Therefore the consensus of opinion at the 
present time is that after the gametes of the various species of 
plasmodia are fully developed quinine has no action upon them, so 
far as rendering them incapable of developing in the mosquito. 
This is not true, however, in the early intracorpuscular stages of the 
development of the gametes , for I have observed marked changes in 
their staining reactions after the administration of quinine which 
lead me to believe that this drug is capable of injuring them and 
probably of entirely preventing their development. 
The observations of Darling 54 and Thomson 55 have shown that 
the administration of large doses of quinine, continued over a period 
of about three weeks, will result in the reduction of the number of 
gametes in the peripheral blood to a noninfectious minimum, i. e., 
to less than 1 to 500 leucocytes, and, according to Thomson, to less 
than 1 per cubic centimeter. This reduction is considered by Thom¬ 
son to be due to the destruction of the asexual parasites from which 
the crescents arise, but I am of the opinion that it is due to the 
destruction of the gametes themselves, during their early intra¬ 
corpuscular stages of development, for reasons already noted. 
The treatment of gamete earners in prophylaxis. —The importance, 
from a prophylactic standpoint, of rendering gamete carriers harm¬ 
less, is self-evident, and the researches of the observers mentioned 
have shown us how this may be accomplished. No patient suffering 
from malaria should be returned to duty until a microscopical exami¬ 
nation of the blood shows that gametes are absent, or at least are 
present in numbers smaller than 1 to every 500 leucocytes. If these 
forms are present in a larger number than this, it is necessary to 
continue quinine in large doses, and both Darling and Thomson, as 
the result of their very careful observations, state that the drug 
should be given in doses of 2 grams (grs. xxx) per day for about 
