Insects and Human Health 525 



Finally Ross secured another kind of mosquito at least it 

 differed in appearance from the Cule'x. Its wings were spotted, 

 while those of the Culex were gray or brown. The new variety 

 is now described in Entomology as maculipennis, meaning spotted 

 wing, and is named the Anopheles. This widely distributed 

 group (cf . page 542) is found chiefly in marsh or swamp country, 

 in contrast with the Culex, which is domestic, or rarely found 

 apart from human habitations. 



His discoveries. In his examination of the new specimen, 

 Ross discovered a number of microscopic bodies attached to 

 the outer wall of its stomach (Fig. 160, 1, 2, 3), the first evidence 

 of the possible presence of the malarial parasite. He found in 

 these bodies minute granules of black pigment which are now 

 known to be a waste product deposited by the adult parasite 

 in its digestion of the substance of the red corpuscles of the 

 human blood. The age of the parasite is indicated by the 

 number of black granules the larger the number the older 

 the parasite. 



With the discovery of the granules it became probable that 

 the Anopheles mosquito was somehow connected with the 

 malarial parasite and the disease. Ross now devoted all of 

 his time and energy to this problem. In time he succeeded not 

 only in proving that the black granules are always found in the 

 mosquito's stomach several days after the insect has sucked the 

 blood of a malarial patient, but also in discovering all the 

 stages in the life history of the malarial parasite in man and in 

 the mosquito. He proved also that the parasite is transmitted 

 only by the Anopheles mosquito. 



256. Life history of the parasite : In man. Knowledge of 

 the life history of the malarial parasite is necessary in under- 

 standing the course of the disease and the r61e played by the 

 mosquito in its transmission. Directly a parasite is introduced 

 into the human circulation through the bite of the Anopheles 

 (Fig. 160, A, B,C, D, E, F, G), it pierces the wall of a red 

 corpuscle, unless it happens to be destroyed by the protective 



