MALARIA. -385 



blood-discs are destroyed in the process of development of 

 the parasites. At the same time an injurious influence is 

 exerted upon the uninfected blood-corpuscles by a parasitic 

 poison dissolved in the blood-plasma. A chemic toxic 

 action on the part of the parasites has, it is true, not yet 

 been established. It is, however, rendered probable by the 

 fact that the urine and the sweat of malarial patients, both 

 of which secretions do not contain the parasite itself, are 

 poisonous to rabbits, and are capable of causing death in 

 these animals. The presence of a poison is also necessary 

 for the explanation of the febrile attack. The paroxysm 

 always sets in with sporulation that is, with disintegration 

 of the completely developed parasite. It is generally as- 

 sumed that in this process, simultaneously with the spores, 

 a poison is set free that is thrown into the blood and gives 

 rise to the fever. Malaria would thus be a form of proto- 

 zoan septicemia presenting analogies with ordinary bacte- 

 rial septicemia. The toxic action would then without diffi- 

 culty explain also the other symptoms the diarrhea, the 

 dyspnea, the ecchymoses, and especially the nervous symp- 

 toms. The bone-pains are usually attributed to the increased 

 demands upon the blood-forming activity of the bone- 

 marrow, and comparable with those observed in leukemia. 

 Coma may be induced by the occlusion of the cerebral 

 vessels with the parasites themselves, and this has been 

 demonstrated microscopically in a number of cases. 



Mode of Infection with Malaria. Cultivation of the 

 malarial parasites has thus far not been successful. Trans- 

 mission of the disease to animals has likewise not been 

 successful, although it has been attempted with numerous 

 varieties. The only positive result that has been obtained 

 'in this connection consists in the survival for forty-eight 

 hours of the parasites within the bodies of leeches that 

 had been applied to malarial patients (Rosenbach). The 

 malarial parasites are known only as blood-parasites of 

 human beings. No conception has hitherto been possible 

 as to where and in what form they exist outside of the 

 human body. For this reason existing knowledge of the 

 manner in which malarial infection takes place, and which 

 is mainly based upon empiric observation, is not very ex- 

 tensive. Malaria may be transmitted from one human 

 being to another by means of the blood. Gerhardt was 

 the first to demonstrate this by subcutaneous injections of 

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