that spread Disease. 9 



of these precaufcious has frequently heen followed l^y marked 

 diminution in the prevalence of malaria, or even its total or almost 

 complete disappearance. 



In a table-case that stands at the entrance to Bay X, near the 

 statue of Prof. Huxley, are shown two greatly enlarged models 

 (x 28) of one of the malaria-carrying species of mosquito, 

 AnopheJcs maculipennis Mg., together with an actual specimen, for 

 the purpose of giving a correct impression of the real size of the 

 insect. The model on the left hand panel shows the attitude of 

 the mosquito w^hen flying (fig. 3, p. 15) ; that on the right hand 

 panel shows its attitude when at rest (fig. 2, a). Both of the 

 models represent the female insect, for in the species of mosquito' 

 that suck blood the blood-sucking habit is confined to the female. 

 In the case of an infected mosquito capable of communicating the 

 disease, the young forms of the malarial parasite escape into the 

 blood with the secretion of the salivary glands, which is introduced 

 into the w^ound at the time of the bite. 



In the middle part of this case is shown a series of greatly 

 enlarged models ( x 6,000) illustrating the complete life-cycle of 

 the parasite of pernicious or aestivo-autumnal malarial fever, 

 Plasmodium falciparum, some stages of which are passed through 

 in the blood of man, others in the body of the mosquito. The 

 models are numbered consecutively, and are explained in the 

 following terms : — 



^■o 



1. — A malarial germ or sporozoite (fig. 1, a), as introduced 

 into the blood of man by the proboscis of a female anopheline 

 mosquito. 



2. — The sporozoite penetrates into a red blood-corpuscle, and 

 becomes rounded off into a compact mass (fig. 1, h). 



3.- — The parasite enlarges and a vacuole appears within it. 

 Signet ring stage. 



4. — The vacuole disappears, and the parasite enlarges and 

 emits blunt processes. Amoebula stage. 



5. — The nucleus multiphes, and the pigment granules increase 

 in number (fig. 1, c). 



6. — The nuclei arrange themselves at the periphery. Rosette 

 stage. 



7. — The daughter-individuals (merozoites) separate from the 

 central non -nucleate protoplasm (fig. 1, d). 



