EXPERIMENTS ON BIRD MALARIA 395 



34. How mosquito-caused infections compare with infections by 

 blood inoculation. (The earlier workers believed that there 

 was a definite difference, and there appears to be such a dif- 

 ference in human malarial infections which are induced by 

 blood inoculation.) 



35. Exactly what the requirements of the parasite are as to oxy- 

 gen consumption, anaerobiasis, glucose consumption, etc. 

 (Such information might pave the way for successful cul- 

 tivation.) 



36. Whether other animals can be infected with the avian malarial 

 parasites. (Koch made a beginning in this field, when he made 

 an unsuccessful attempt to infect a monkey.) 



37. Whether blood serum is toxic to the merozoites as has been 

 claimed. 



38. Whether there are other species of bird malaria. 



39. Whether changes can be induced in the parasite by exposure 

 to various agents while in the mosquito. (Since the sexual 

 stage in the life history takes place in the intermediate host it 

 would seem that such changes could be more easily induced 

 then. Radiation of diff'erent sorts would be a desirable agent 

 to experiment with.) 



40. A critical and careful study of infections produced before and 

 after mosquito passage might be of considerable biological 

 interest. 



41. Whether the parasites are experimentally infective to birds 

 at any stage before the sporozoites are liberated from the 

 oocyst. 



42. What constitutes resistance to infection in the mosquito. (It 

 might be possible to test whether such resistance was heritable 

 by experimental means.) 



43. Whether the proportion of gametocytes varies with the sea- 

 son, as has been suggested by Ross and others, and indicated 

 by the work of Manwell, 1929. It should be determined 

 whether, if such a variation really occurs, it is a real varia- 

 tion in the proportion of gametocytes to asexual forms, or 

 whether it is only an apparent variation, due to the greater 

 severity of relapses in the seasons in question. 



44. The length of the asexual cycle in Plasinodhim inconstans and 

 Plasmodium prcecox. 



45. Are there any other measurable or detectable dift'erences be- 



