BY DR. A. JEFFERIS TURNER, M.D. LOND., D.P.H. CAMB. 107 
siphon, situated towards the tail, while the head hangs 
nearly vertically downwards. Anopheles larvae have no 
projecting siphon, and rest nearly horizontally on the surface 
while breathing. The mature Culex, when it alights, rests 
with the body horizontal, and the head well elevated. 
Anopheles rests with the body steeply inclined, and the 
head depressed, as though the proboscis was pinned into 
the surface rested on. The species are more quiet and 
retired in their habits than those of the Culex group, and 
need to be searched for, while the latter make their presence 
evident, whether we wish it or no. 
We are now able, thanks to the work of later observers, 
to give the complete life-cycles of the malaria organism 
both in man and the mosquito. First we have the asexual 
circle as already described, occurring in the blood of the 
human host. It is now known that sexual forms also 
occur in human blood. They are most easily distinguished 
in the pernicious variety of malaria, where they are sausage- 
shaped, distorting the containing corpuscle to form 
the familiar “‘ crescent bodies.” The male and female 
forms can be distinguished by slight differences in the 
size and staining of the nuclei and cell granules. Confined 
to the human body, the male forms undergo no further 
development and die out. The female forms are more 
resistant, and indeed are capable of surviving when al] the 
remaining forms of the parasite are killed off by quinine, 
or by the natural resistance of the host. When, however,- 
this resistance is lowered by some external cause, such 
as a chill, they undergo a parthenogenetic development. 
The nucleus divides into two parts, the darkly staiming 
portion divides into spores as in the asexual cycle, the paler 
portion which represents the sexual element is abandoned 
as useless to the organism. Meanwhile the unfortunate 
host experiences a relapse of his ague. 
But when the blood is imbibed by a mosquito, the 
course of development is altogether different. The digestive 
juices of the insect destroy all but the mature sexual stages 
of the parasite. The crescents slip out of their corpuscles, 
and assume a rounded form, and undergo development. 
The nucleus of the male is transformed into the threads 
commonly known as flagella, but more accurately termed 
