io (niidc to Insects and Ticks 



8. The merozoites become free in the blood-plasma by the 

 disintegration of the red corpuscle (fig. 1, c). Each merozoite 

 invades a red blood-corpuscle, and develops into amoebula, rosette, 

 and further merozoites, as explained in the preceding models. 



9, 10. After several cycles of amoebula, rosette, and 

 merozoites, a merozoite on entering a red corpuscle grows into a 

 sexual form which may be crescentic (fig. I,/). 



11. The crescent increases at the expense of the corpuscle, 

 and male crescents become distinguishable from female crescents, 

 as explained in models 12 and 15. The crescents undergo no 

 further change in human blood, but when blood containing 

 crescents is sucked by a female anopheline mosquito, the crescents 

 undergo development. 



12. The male crescent (fig. 1, g) is shorter and more rounded 

 than the female crescent. It has clearer protoplasm and a larger 

 nucleus, and the pigment granules are more scattered. 



13, 14. The male crescent becomes spherical and the nucleus 

 multiplies. 



15. The female crescent (fig. 1, li) has denser protoplasm and 

 aller nucleus than the male, and the pigment granules are in 

 the middle part of the crescent. 



16, 17, 18. The female crescent becomes spherical, and, after 

 extruding two small cells (? polar bodies) in succession, becomes 

 the niacrogamete or ovum, and is ready for fertilisation. 



19. The male sphere shoots out four, five or six slender pro- 

 cesses (microgametes or sperms) consisting mainly of nuclear 

 material (fig. 1, i). The remainder of the sphere plays no further 

 part in the life-history. 



20. A microgamete is attracted by, and enters into an ovum 



(% U). 



I I-;. 1. LIFE HISTORY OF THE ORGANISM OF PERNICIOUS MALAUIA. 



". malarial jjerin or spoi o/<,itc. a> introduced into the blood of man by :i female 

 anopheline mos.jnito at the time \\hen it is sin-kin-.: Mood; b, gporo/oite after cut ry into a 

 blood-corpuscle of man; r, growth of the spoi-o/oite into an amocbiila ; </, division of the 

 ila to form inei-o/oiu-s; e , liberated inen./oite- : /. growth of a mero/oite into a 

 crenceiit ; .-;. free malt- cri-scen( ; A, five female crescent; t, male cell with projections. 

 which lengthen and are set free as Bpei ins ; /', fcrtili.-ation of an ovum by a sperm ; A;, ferti- 

 lised egg an an a. ti\e motile veimicule ; /. sj)here formed from the enlar-.-d \. rmicnle. after 

 this has borod thron-h tin- .-tomach-vvall of (he nioM|iiito: //(. portion of the sphere or c\ >l 

 ftt a late Hta ; ment . containing eoiintle- ne.-dle-ha].ed IpOTM, \\lii--h. s\lien ( he 



urstB, escape a8I>]-. l /-.ite. int., the oi-an- of the mo-,|uit..- body, and pass through 

 the salivary glauds into the pr..bo,ei^. and IO infect a man bitten (i.e. pricked) by the 

 -I 1,600 -li :- ih-a\\n to a smaller .--ale of ma-_'iiilieation. 



