280 APPLIED BACTERIOLOGY 



recently established that the organisms causing the 

 various types of malarial fever are distinct parasites, and 

 are not, as was first thought by Laveran and others, due to 

 one polymorphous organism. There is still a difference of 

 opinion as to the exact number of varieties. 



Undoubtedly the severity of malarial attacks is largely 

 governed by the extent of the parasitism occurring in the 

 blood-corpuscles. As already stated, malaria is charac- 

 terized by a decided intermittency, periods of chill and 

 fever, corresponding to the life cycle of the organism in the 

 blood. The paroxysms of the disease, as represented by the 

 chill, correspond with the escape of the spores from the 

 mature organism into the blood serum. When these again 

 invade the corpuscles, the fever diminishes, and during their 

 growth until the next state of sporulation the patient has 

 a respite from the more severe symptoms. The species of 

 parasite may be arranged as follows : 



(a) Quartan. — This is a benign variety, and depends on 

 a parasite which takes seventy-two hours to pass through its 

 cycle of development. The flagellated bodies, when they 

 occur, are formed from spheres. The red corpuscles 

 invaded by the parasite do not become decolourised or 

 altered in shape. 



(6) Tertian. — The cycle of development of this parasite 

 takes forty-eight hours for completion. The organisms 

 within the corpuscles show much greater movement than 

 in the quartan type. Flagellated bodies are formed from 

 spheres. Both the above varieties of fever are known as 

 winter-spring fevers by Italian writers. 



(c) Malignant Tertian.— l!\ns form requires about forty- 

 eight hours for development. The organism is relatively 

 minute, and is very actively amoeboid when young, the 

 parasite assuming a 'ring' form after a time. Its more 

 advanced or sporulative stage is completed in the blood- 



