44 
PROPHYLAXIS OF MALARIA. 
sinensis could be infected with the plasmodia of tertian and quartan 
malaria but not with those of aestivo-autuninal malaria, and that 
the quartan plasmodium only developed in this species of mosquito 
at low temperatures. He also has shown that Anopheles listoni is 
the great transmitter of the aestivo-autumnal plasmodia in Formosa. 
M any observers have proven that the common Anopheles maculi- 
pennis is an efficient host for all of the species of malaria plasmodia. 
The observations noted explain clearly why certain localities suf¬ 
fer more severely than others from certain types of malarial infec- 
tion. Given a locality in which only Anopheles crucians occurred 
and we would have nothing but aestivo-autumnal infections, as this 
mosquito is unable to transmit the tertian or quartan plasmodia, 
but if Anopheles quadrimaculatus were the only anopheles present, 
we might have either tertian or quartan infections but no aestivo- 
autumnal malaria. It is, therefore, evident that a mosquito survey 
is not only of value in determining whether dangerous species of 
Anopheles are present or not, but that it will also aid us in estimat¬ 
ing the probability of the spread of the various types of malarial 
infection. 
General description of the Anophelince. —The following brief de¬ 
scription of the anatomy of the Anophelince only includes the points 
of value in the differentiation of these mosquitoes or that are essen¬ 
tial to a clear understanding of the relation that these insects bear 
to the transmission of malaria. 
External anatomy. —All mosquitoes are divided into three well 
marked areas for purposes of description: the head, the thorax, and 
the abdomen. 
The head presents upon each side a prominent compound eye, 
the space separating the eyes above being known as the occiput , and 
that separating the eyes in front as the vertex; the back of the head 
is called the nape or neck. The structures of greatest importance 
from a diagnostic standpoint attached to the head are the antenna ? 
and the palpi , for attention to these structures alone is generally 
sufficient to enable one to distinguish between the Anophelince and 
other mosquitoes. The antennce are two jointed structures arising 
from the head and vary in length and structure. In the male they 
are plumose but in the female they are surrounded by hairs, in most 
species, so that the sex of a mosquito is easily determined by noting 
whether the antennce terminate in minute plumes or whether they 
are surrounded by hairs that become shorter as the end of the 
antenna is reached. As only the females suck blood the detenni- 
*/ 
nation of the sex is of importance in any study of the prevalence 
of malaria. 
The palpi , two in number, arise from the head between the an- 
iennce and the proboscis , and are of value in the differentiation of 
