PARASITIC BACTERIA. 163 



and during their growth in the corpuscle until 

 the next sporulation the individual has a rest 

 from the more severe symptoms. 



There appears to be more than one variety of 

 the malarial organism, the different types differ- 

 ing in the length of time it takes for their growth 

 and sporulation. There is one variety, the most 

 common one, which requires two days for its 

 growth, thus giving rise to the paroxysm of the 

 disease about once in forty-eight hours ; another 

 variety appears to require three days for its 

 growth ; while still another variety appears to be 

 decidedly irregular in its period of growth and 

 sporulation. These facts readily explain some of 

 the variations in the disease. Certain other ir- 

 regularities appear to be due to a different cause. 

 More than one brood of parasites may be in the 

 blood of the individual at the same time, one 

 producing sporulation at one time and another at 

 a different time. Such a simultaneous growth of 

 two independent broods may plainly produce al- 

 most any kind of modification in the regularity of 

 the disease. 



The malarial organism appears to be very 

 sensitive to quinine, a very small quantity being 

 sufficient to kill it. Upon this point depends the 

 value of quinine as a medicine. If the drug be 

 present in the blood at the time when the spores 

 are set free from the blood-corpuscle, they are 

 rapidly killed by it before they have a'chance to 

 enter another corpuscle. During their growth in 

 the corpuscle they are far less sensitive to qui- 

 nine than when they exist in the free condition as 

 spores, and at this time the drug has little effect. 



The malarial organism is an animal, and can 

 not be cultivated in the laboratory by any arti- 



