ition of his work.
A few years ago he was awarded the Nobel prize for medicine, perhaps the
highest honor that can be bestowed on any physician. It is interesting,
too, to note in this connection that it was another French surgeon who
in 1840 discovered that sulphate of quinine is a specific for malaria.

[Illustration: FIG. 96--Horse and cattle tracks in mud filled with
water; good breeding-places for Anopheles.]

[Illustration: FIG. 97--A malarial mosquito (_Anopheles maculipennis_);
male.]

[Illustration: FIG. 98--A malarial mosquito (_A. maculipennis_);
female.]

The next important step was made in 1885 by Golgi, an Italian, who
studied the life-history of the parasite in the blood and distinguished
the three forms which cause the three most familiar kinds of malarial
fevers, the tertian, the quartan and the remittent types. From this time
on this parasite has been studied by physicians of many nationalities
and the whole course of its life-history worked out. In order that we
may understand how it was that mosquitoes were determined to be the
means of disseminating this parasite we will discuss first its
life-history in the human blood.

The parasites that cause the malarial fevers are Sporozoans and belong
to the genus _Plasmodium_. Other names such as _Haemamoeba_ and
_Laverania_ have been used for them, but the term _Plasmodium_ is the
one now most commonly employed. The three most common species are
_vivax_, _malariae_ and _falciparum_, causing respectively the tertian,
quartan and remittent fevers.

LIFE-HISTORY OF PARASITE

The life-history of all of these is very similar, the principal
difference being in the length of time it takes them to sporulate. Let
us begin with the parasite after it has been introduced into the blood
and trace its development there. At first it is slender and rod-like in
shape. It has some power of movement in the blood-plasm. Very soon it
attacks one of the red blood-corpuscles and gradually pierces its way
through the wall and into the corpuscle substance (Fig. 99); here it
becomes more amoeboid and continues to move about, feeding all the
time on the corpuscle substance, gradually destroying the whole cell. As
the parasite feeds and grows there is deposited within its body a
blackish or brownish pigment known as melanin.

During the time that the parasite is feeding and growing it is also
giving off waste products, as all living forms do in the process of
metabolism,