SPOROZOA 195 



belonging to the order Hemosporidia. The parasites are 

 called the Plasmodium vivax, the P. malaria, and the P. 

 falciparum. Three types of attack correspond to the three 

 protozoal species: (1) That which gives chills and fever 

 every third day, the tertian malaria; (2) one where the 

 paroxysm appears every fourth day, the quartan type, and 

 (3) a continuous, typhoid-like type, the malignant or estivo- 

 autumnal fever. 



The species vary in finer morphological details, but they 

 follow the same course in their transmission and develop- 

 ment in regard to infectivity, except that they require differ- 

 ent times for their full development. 



a b 



FIG. 65. Egg of Culex (a) laid together in "small boat;" those of Anopheles 

 (6) separate and rounded. (From Kolle and Hetsch.) 



The female mosquitoes of the genus Anopheles carry the 

 disease from one person to another. They fly and bite in the 

 early evening. These mosquitoes may be recognized by their 

 position on a surface. Their body forms a large angle with 

 the surface, and the head is on a line with the body. The 

 ordinary mosquito, Culex, stands parallel with the surface 

 with the head bent down. Furthermore, the wings of the 

 Anopheles are furred on the flat surface, while the Culex 

 wings are only fitted with widely set, fine hairs on the edges. 

 There are many other differences, but these will suffice as 

 general guides. The female mosquito bites a malarial person 

 and receives the parasites into her stomach. Here they 

 undergo reproduction by a sexual process, and appear in her 

 salivary gland in a condition ready for transmission to the 

 next person bitten. This gland is connected with the biting 



