DAHLGREN, THE MALARIA MOSQUITO 35 



As the result of the laborious researches of these scientists, we now 

 know that malaria is not communicated except by the Malaria Mosquito, 

 that this is a member of the genus Anopheles, and that consequently, 

 malaria does not exist in any locality in the absence of mos- Malaria 

 quitoes of this genus. While it is highly probable that all of and 



the forty or more species of the genus, distributed over almost Anopheles 

 the entire world, may carry malaria, ability to harbor and transmit the 

 malarial parasites lias been actually proven of only about half the num- 

 ber. The majority of the species known to be malarial occur in India. 

 The only European or North American member of the genus which 

 stands at present positively convicted of carrying the disease, is the one 

 figured and described in this paper, Anopheles macvlvpennis Meigen. 

 That other mosquitoes, for instance, the common Culex, of which so 

 many species exist everywhere, are as likely as Anopheles to imbibe 

 malarial blood is unquestionable, but in all mosquitoes, except certain 

 Anopheles, the human malarial parasites seem to perish in the alimen- 

 tary tract of the insect, or the spores are perhaps destroyed by the more 

 acid secretion of the salivary glands. 



The malarial organisms are unicellular animals, "protozoa," of the 

 class Sporozoa, all members of which are parasitic. The members of 

 the order to which they belong, the HcBmosporidiida, are parasitic in the 

 blood of higher animals and resemble the malarial organisms in their 

 life-history. Thus, there is a parasite of "bird malaria" found in 

 pigeons, crows and bluejays, Halteridium, transmitted by a Culex mos- 

 quito; and another, Proteosoma, which lives in the blood of sparrows 

 and is also carried from one bird to another by a mosquito. 



When a malaria-infected mosquito bites, the poison or saliva which 

 is injected into the wound carries into the human circulation some minute 

 needle-like or elongated spindle-shaped bodies. These are the malarial 

 spores (Fig. 32, S). Once in the human circulation, each The Malarial 

 spore, of which there may be half a hundred, enters a red Spores in 



blood corpuscle (Fig. 27, A, B), loses its characteristic 

 form and becomes a minute, rounded, amoeboid parasite. After its 

 entrance, this measures one fifth to one fourth of the diameter of the 

 blood cell; but, nourished by the contents of the corpuscle, it grows 

 rapidly (Fig. 27, (', D). The blood corpuscle in which it lives, loses its 

 circular outline, becomes enlarged, and, in a short time, is nearly filled 

 by the growing parasite (Fig. 27, E). At the same time the nucleus of 



