THE PRESENT EPIDEMIC OF MALARIA. 875 



through which the malaria parasite passes in the course of its de- 

 velopment. 



The malaria parasite occupies a very humble position in the ani- 

 mal kingdom, being classed among the Protozoa. Let me intro- 

 duce you to this creature as you will find it in the blood of a patient 

 suffering from the disease, just at the commencement of an attack of 

 fever. The parasite then appears, after suitable preparation, as a 

 minute ring living within the substance of a rod blood cell* (Fig. 2). 

 Hour by hour it grows in size converting the red colouring matter of 

 the red blood cell into a black pigment till the whole «f the substance 

 of the cell is destroyed and-the parasite has reached maturity (Figs. 3 

 to 6). This may occupy a period of from 48 to 72 hours. The para- 

 site then divides into a number of segments, spores, or seeds which, 

 separating from one another, attack and enter fre«b red blood cells to 

 repeat in them a similar cycle of development (Figs. 7 to 10). A time, 

 however, soon comes in the course of the disease, when certain indivi- 

 duals are developed which, as they grow larger, in place of dividing 

 into a number of spores, become differentiated into male (Figs. 11, 

 12) and female (Figs. 15, 16) elements. These latter forms of the 

 parasite remain in the blood awaiting a favourable opportunity to be 

 transferred to the body of a mosquito when that insect comes to suck 

 the blood of our patient. If by good luck this mosquito happen to be 

 a particular kind of anopheles and if it has had a good feed on the 

 patient's blood the male and female parasites, which have been taken 

 into the mosquito's stomach with the blood, conjugate there (Figs. 

 13, 14 and 17, 18), producing by their union a minute motile worm- 

 like body (Fig. 19), which immediately proceeds to pierce the 

 stomach wall of the mosquito. Having entered the stomach wall cf 

 the mosquito the parasite comes to rest surrounding itself with a 

 capsule among the cells of that organ (Fig. 20). Here it gradually 

 increases in size and by n process of multiple division produces a vast 

 number of very minute spindle shape forms within its capsule 

 (Figs. 20 to 26). When mature these spindle forms escape into the 

 body cavity of the mosquito and make their way to the salivary or 

 poison glands of the insect. In these glands they find lodgment, 

 particularly in the gland secretion, and are now ready, when 

 the mosquito thus infected bites man, to be injected beneath his skin 

 * The reader should follow the development of the parasite in the diagram (Plate A). 



