MALARIA AND ITS TRANSMISSION 23 



speculation every forty-eight or seventy-two hours, 

 as the case may be) (Fig. 4, 1-6), is passed within the 

 human body ; therefore if a human were only once 

 infected with malaria and were to undergo no treat- 

 ment, the parasites would probably eventually dis- 

 appear, even in the absence of treatment, owing to 

 their senescence after repeated asexual sporulation, 







Fig. 3. Signet ring stage of malaria parasite. 



and what is probably more important, the production 

 of a toxin which is destructive to the parasites. There 

 is apparently, however, parthenogenesis, in which 

 female crescents give rise to new blood-cell attacking 

 parasites, which may give rise to a recurrence of the 

 malaria paroxysm even after a long latency. There- 

 fore in order to continue the race, i.e. to provide for 

 sexual rejuvenation, these parasites must find their 



