288 THE PATHOGENIC HEMOSPORIDIA 



there is no subsequent reproduction. It happens in most of the 

 common rhizopods, for example, and has been described for cases of 

 arcella, difflugia, centropyxis, ameba, etc., and it has been shown that 

 these unions have nothing to do witli the actual process of fertilization. 

 It is impossible to state that no stimulation whatsoever results from 

 such a plastogamic union, especially if it is followed by nuclear union 

 or karyogamy, according to the account given by Craig; but it is diffi- 

 cult to believe that two widely different processes of fertilization should 

 exist in the same organism. My experiences with the free living Para- 

 mecium in cases of depression where the organisms were stimulated 

 to new activity and new reproduction by purely artificial means 

 opens the possibility, at least, that some analogous stimulation in the 

 human system may start up the flagging energies of the malarial 

 parasites. It is not inconceivable that minute changes in the con- 

 stitution of the blood, especially of the salt contents, act upon the 

 parasites in the same manner that potassium phosphate acts upon the 

 weakened paramecium. 



Apart from the clinical effects of the different malaria parasites 

 there is not much difference between them. The cause of quartan 

 fever, Plasmodium malariw, for example, agrees in all of its phases 

 with Plasmodium vivax, the most important difference being the period 

 elapsing between successive sporulating phases, requiring seventy-two 

 hours as against forty-eight. The forms assimied by the gametocytes 

 agree in all essential features, and fertilization in the mosquito follows 

 the same history as in Plasmodium vivax. 



There is evidence that at least two kinds of parasites causing 

 pernicious malaria exist, one giving rise to a daily and the other to 

 a forty-eight-hour recurrence. The difference in form of the macro- 

 gametocyte was considered evidence of sufficient morphological value 

 to justify a different generic name, and Grassi, therefore, gave it the 

 name l^averania malarias. The grounds seem hardly sufficient for 

 this, however, and the name Plasmodium falciparum, as given by 

 Welch, is the one we adopt. (PI. immaculatum, accepted by Schaudinn, 

 was shown by Blanchard to be the name given by Grassi and Felletti 

 to parasites occurring in birds.) In this parasite the macrogamete 

 assumes the form of a crescent before maturity, but rounds out into 

 a perfect sphere before fertilization. 



The action of quinine on the malaria organisms is particularly 

 interesting, since it is one of the best-known specifics against any 

 of the protozoan diseases. Introduced into Europe, in 1640, by del 

 Cinchon, it was immediately recognized as a specific and was used as 

 a diagnostic therapeutic test for malaria. Just how it acts upon the 

 malaria organism was, of course, unknown until more or less of the 

 life history of the parasites was known. Marchiafava and Celli, 

 Schaudinn, and, in short, all who have studied the matter carefully 



