MALARIA. 365 



during any time but just before, during, or soon after rigor. If we wish 

 to see the early and unpigmented forms, we must look for them during 

 the later stage of rigor or the earlier part of the stage of pyrexia. And 

 so with the other stages of the parasite; each has its appropriate rela- 

 tionship to the fever cycle." 



There are numerous cases of malarial fever in which there is no dis- 

 tinct intermission and in which the course of the fever is either con- 

 tinued or remittent in character. Fevers of this type usually occur in 

 the late summer or in the autumn (sestivo-autumnal) and are believed to 

 be due to infection by two distinct varieties of the parasite; one, the 

 tertian sestivo-autumnal, causes a fever characterized by a marked rise in 

 the temperature every second day; the other, a fever in which there is a 

 daily elevation of temperature. There are certain peculiarities relating 

 to the intra-corpuscular development of these parasites which enable us 

 to differentiate them from the tertian and quartan parasites of intermit- 

 tent fever, but a more striking difference to be observed in their life 

 cycle of development in the blood of man is the presence of peculiar cres- 

 centic-shaped bodies, which play an important part in their further de- 

 velopment in the body of an intermediate host — the mosquito. Asso- 

 ciated with these 'crescents' fusiform and ovoid bodies are often seen 

 which are no doubt similar in their origin and function. The crescents 

 are a little longer than the diameter of a red blood corpuscle and are 

 about three times as long as broad. They contain in the central portion 

 grains of pigment (melanin) derived from the haemoglobin of the in- 

 fected corpuscle which has been changed into a crescentic body as a re- 

 sult of the development of the malarial parasite in its interior. When a 

 fresh preparation of malarial blood containing these crescents is ob- 

 served under the microscope, while a majority of them retain the cres- 

 centic form, others may be seen, after an interval of ten minutes or 

 more, to change in form, first becoming oval and then round; then, in 

 the interior of these round bodies an active movement of the pigment 

 granules occurs; this is followed by the thrusting forth from the peri- 

 phery of several filaments — usually four, which have flagella-like move- 

 ments. These, as a rule, become detached and continue to move rapidly 

 among the blood corpuscles. With reference to the function of these 

 motile filaments, Marchiafava says: 



"In these later days there is increasing belief in the theory, which 

 we uphold, that the crescents and the flagellata are sexual forms of the 

 malarial parasite, and that a reproductive act (in which the flagellum 

 represents the male element and an adult crescent the female cell) gives 

 rise to the new being which begins its existence in the tissues of the mos- 

 quito.^ 



These crescentic bodies may be found in the blood of man long after 

 all febrile symptoms have disappeared, and it is generally recognized 



