304 



8. Action of Quinine on Parasites. — Quinine 

 although it does not prevent fission yet destroys 

 the young ring forms. 



As is well pointed out by Marchiafava and 

 BiGNAMi, the ensuing attack may still lack nothing 

 in severity, although parasites are exceedingly 

 scanty. 



Although this may be considered as the 

 typical action of quinine, yet there are cases, as 

 anybody who has observed really severe cases of 

 tropical fever, e.g., in West Africa, well knows, in 

 which quinine has not always this inhibitory 

 effect. 



In such cases the number of parasites may 

 be exceedingly small or even absent, and yet the 

 severity of the symptoms persist. To those cases 

 where witli severe symptoms and yet an absence 

 of parasites and to those cases where other 

 factors promote the rapid disappearance of para- 

 sites we shall refer in the succeeding section. 



1. On YoMW^ ParaszYes (malignant tertain).— 

 When quinine is given at the time of their 

 first appearance in the circulation, the parasites 

 continue in the circulation for a variable period 

 of time depiending upon the amount, of quinine 

 and probably on other unknown factors. Al- 

 though! parasites are still found yet their growth 

 is arrested, and the outburst is not followed 

 by large forms, presegmenting, and eventually 

 fission forms. It must be noted that quinine 

 may have no such inhibitory effect at all. 



2. On Large Parasites. — The parasites still 

 go on developing as far as presegmenting and 

 segmenting forms, but generally there is no 

 subsequent production of young forms. 



