Coccidiomorpha 



97 



bird by means of various culicine mosquitoes, the best vectors being 

 Culex pipiens and C. jatigans [see Huff, p. 386] . The mosquitoes must 

 engorge on the infected bird at a time when gametocytes are present in 

 the blood. Their bites are infectious for other birds after 8 to 14 days 

 depending upon the species of the parasite and the temperature of the 

 environment. Plasmodium circumflexum does not infect these common 

 mosquitoes but it has been shown by Reichenow (1932) to be trans- 

 mitted by Theobaldia anmdata. While several of the species of culicine 

 mosquitoes become infected in small percentages when fed on birds with 

 infections of Plasmodium elongatum and P. rouxi, no complete trans- 

 mission has yet been effected by any of them. 



Fig. 43. — Mosquito-proof cage. 



Unless there is some special reason why mosquitoes are preferred as 

 the means of transmission, all of these strains may best be maintained in 

 canaries and passed when desired by blood inoculation. Infections pro- 

 duced by any of these species of parasites go through an acute stage 

 which is followed by a latent period of infection of long duration. Spon- 

 taneous cure is rare. Therefore, in most cases, the strains may be main- 

 tained most easily as latent infections. New infections may be produced 

 in normal birds by inoculating them with blood from the birds with 

 latent infections. A few drops of blood are taken from a leg vein into 

 physiological saline solution (0.85%) and injected by means of a syringe 

 and inoculating needle into a normal bird. This may be done intra- 



