IMMUNOLOGY 847 



gested that their death is due to the destruction of multiple infected 

 red cells. 



It is interesting that in 1888 Golgi noted that malaria would always 

 be progressive until pernicious symptoms were evident, if the parasites 

 arriving at maturity every two days in tertian or every three days in 

 quartan malaria should complete their life cycle. W. H. Taliaferro and 

 L. G. Taliaferro (1934a) found that out of an average of 9 progeny 

 produced by P. brasilianum, never more than 1.5 complete their develop- 

 ment and of the 7.5 which fail to complete their development, about 6 

 fail to get into new cells and 1.5 die or are killed during intracorpuscular 

 growth. Thus, in Figure 188 on the morning of May 1 there were 60 

 parasites per 10,000 red blood cells. That evening after sporulation, 

 there were 221, an increase of 3.66 times instead of 9 times. During 

 the subsequent 2.5-day period of growth and division, about two-thirds 

 of these were destroyed, so that on the morning of May 4 there were 

 only 83 per 10,000 red cells. Similar data are furnished by Brug (1934) 

 and W. H. Taliaferro and Mulligan (1937), who worked on infec- 

 tions with P. knoivlesi and P. cynomolgi; and by Pijper and Russell 

 (1925, quoted by Sinton et al, 1931), by Rudolf and Ramsay (1927), 

 by Sinton et al. (1931), and by Lowe (1934), all of whom worked on 

 one or both of the tertian and quartan malarias of man. Knowles and 

 Das Gupta (1930) believed that the destruction of parasites takes place 

 only during the free merozoite stage. Examination of their tables, how- 

 ever, shows that the infection they studied was made up of several 

 broods of parasites, the sporulation of one of which would obscure a 

 decrease of parasites during the intrasporulation period of another brood. 



The constant rate of death of large numbers of parasites during the 

 initial part of the infection is a manifestation of natural immunity and 

 represents the suitability of the hosts' blood to the malarial organism. 

 The crisis, on the other hand, represents the beginning of the immune 

 reaction, when more progeny die than survive and the infection therefore 

 declines. Thus the crisis in Figure 188 takes place after the sporulation 

 of May 4 and between May 5 and May 7, as shown not only by the 

 conspicuous death of parasites during the intersporulation period of 

 May 5 and May 6, but by the relatively slight increase of parasites during 

 the sporulation on May 7. This infection, which was the most acute 

 encountered, caused the death of the monkey on May 9. The temperature 



