DISEASES TRANSMITTED BY MOSQUITOES 253 



a type of trophozoite which forms sexual bodies known as macrogame- 

 tocytes and microgametocytes. These are the bodies which, when taken 

 up by a mosquito, develop in the mosquito's body through the cycle of 

 sporogony. In the stomach of the mosquito the microgametocytes divide 

 into many tiny, elongate microgametes. The macrogametocytes change 

 into macrogametes, and then conjugation of the gametes takes place. 

 The resulting zygote is spherical, but it soon elongates into a small, worm- 

 like body which is actively motile. It is then known as the ookinete. In 

 this stage it bores into the epithelium of the gut wall and becomes rounded 

 and thinly encysted. When encysted it is kno\vn as the oocyst. In this 

 form it grows considerably in size and divides into sporoblasts, which 

 divide into sporozoites. These tiny forms migrate into the salivary glands 

 and are inoculated into a man at the time of a blood feast. 



The species of human malaria are Plasmodium vivax Grassi and 

 Feletti (1892) causing the tertian disease, Plasmodium malaria Laveran 

 (1881), causing the quartan disease, and Laverania falciparum (Welch, 

 1897) (also known as Laverania malaria Grassi and Feletti, 1890, or 

 Plasmodium falciparum), causing subtertian, malignant tertian, or 

 aestivo-autumnal malaria. 



Many species of mosquitoes of the group Anophelinae have been 

 charged with carriage of malaria but in many cases the evidence does not 

 show what species of organism is carried. The evidence is briefly sum- 

 marized below (see also Hindlc, pp. 96-107). 



MALARIA OF UNKNOWN SPECIES.— The following species of 

 mosquitoes are recorded as carriers or thought to be carriers of some form 

 of malaria. These Anopheles are often arranged in various subgenera, 

 which are, however, omitted from our discussion. 



Anopheles aitkeni James {fragilis Theobald) is suspected as a malaria 

 carrier by Daniels and Christophers (Hindle, p. 29). 



A. algeriensis Theobald was found by Sergent and Sergent in Al- 

 geria to be a carrier in nature, the sporozoite state being found. 



A. apicimaculata Dyar and Knab has been suspected to be a carrier 

 in Central America, but Darling records negative results. 



A. arahiensis Patton was found in nature carrying sporozoites by 

 Patton in Aden Hinterland (Hindle). 



A. ardensis Theobald appears to Castellani and Chalmers (p. 665) 

 as a probable carrier of malaria in Natal. 



A. holiviensis Theobald (lutzii Theobald) is suspected by Lutz to 

 be a carrier in Brazil on what Knab (1913) considers insufficient 

 grounds. 



A. hraziliensis Chagas is cited by Brumpt (1913, p. 748) as a pos- 

 sible carrier of malaria in Brazil. 



