EXPERIMENTS ON BIRD MALARIA 397 



shown to exist in cases infected with Plasmodiinn cathe- 

 merluni) merely a function of the increasing age of the bird? 



63. Is there any "age resistance" on the part of the host to 

 malarial infection? (Entirely apart from any possible im- 

 munity resulting from infection in early life.) 



64. Just how soon, under ordinary conditions, does the blood of 

 a newly infected case become infective? 



65. Can a method be devised for the quick diagnosis of latent 

 infections (as by serum test) ? 



66. How often does complete recovery take place in untreated 

 infections with the different species? 



6"/. Exactly how do the parasites injure the host (other than by 

 blood cell destruction) ? 



68. Do the various agents which will produce relapse have any- 

 thing in common? (i.e., Do they produce the same effect on 

 the host, or is there something fundamentally similar in the 

 agents themselves?) 



69. What is the mechanism of resistance to malarial parasites? 



70. Does resistance to superinfection in the case of a bird carry- 

 ing a chronic infection mean that no amount of superinfection 

 will produce an acute attack? 



71. What effect do physical agents, such as light of various sorts, 

 heat, excessive cold, humidity, barometric pressure, etc., have 

 on the resistance of the host? 



72. How is this effect exerted, and do differing agents produce 

 the same effect on the host in the same or different ways ? 



73. What measurable or perceptible changes does the disease pro- 

 duce in the host — e.g., changes in metabolism, etc.? 



74. Splenectomy has been tried in human malaria. What effect 

 would it have on avian malaria ? 



75. What factors are responsible for the definite length of the 

 cycles in the case of the parasite, and are these inherent in 

 the host, or in the parasite (or, more probably, to some ex- 

 tent in both) ? 



76. Whether relapses are primarily due to changes in the resist- 

 ance of the host (as seems most likely) or whether there are 

 changes in the virulence of the parasite. 



