396 RESEARCH IN PROTOZOOLOGY 



tween the oocysts of various species than those already re- 

 ported in size (Huff, 1927) ? 



46. Whether the proportion of male to female gametocytes can 

 be changed in any way. 



47. Whether this proportion is noticeably variable in different 

 cases, and whether it is approximately the same or signifi- 

 cantly different in different species. 



48. Acton and Knowles (19 14) beheved they found clear evi- 

 dences of parthenogenetic development of the macrogameto- 

 cytes in vitro in the case of the halteridium parasite of the 

 pigeon. Does this ever happen in any of the species of bird 

 malaria ? 



49. Whether the number of parasites necessary to produce an 

 infection is different in the different species. 



50. How many sporozoites of the different species are necessary 

 to bring about infection. 



51. What the length of life of gametocytes Is. 



52. Whether the male and female gametocytes are equally resist- 

 ant to various agents. 



C. The Host: 



53. Where in the body of the host are parasites chiefly destroyed? 



54. To what Is the great congestion in the spleen due? 



55. Are gametocytes destroyed chiefly In the spleen, as some 

 believe ? 



56. What effect does malnourishment have on the resistance of 

 the host to malarial infection? 



57. What is the effect of fasting In inducing relapse? (Casagrandi 

 believed it an important etiological factor.) 



58. What effect would lack of vitamlnes have on the resistance 

 of the host? 



59. What features of the environment are most important in (a) 

 the production of relapse, and (b) favoral^ly affecting the 

 course of the disease? 



60. In what part of the body of the host does segmentation chiefly 

 occur in the case of Plasmodiuin prcecox? 



61. How do the different species compare with respect to the 

 liability to relapse as the time after the original infection in- 

 creases ? 



62. Is this increase in the frequency of relapse (wliich has been 



