780 THE ILEMATOZOON OF MALARIA 



1. Plasmodium malarias. This is the parasite of quartan fever : its life- 

 cycle occupies 72 hours, and the young forms exhibit very slow amoeboid move- 

 ments. The intra-corpuscular amoeboid bodies are smaller than a normal 

 erythrocyte. The pigment grains are numerous and large and show very little 

 movement. The parasite forms a rosette made up of 6 to 12 merozoiites with 

 the pigment all collected in the centre : it does not form crescent gametes. 



2. Plasmodium vivax. The parasite of benign tertian malaria ; its life- 

 cycle occupies 48 hours, and the young forms show more active movements 

 than the young forms of P. malarice. The amoeboid forms are larger than a 

 red blood corpuscle, and the infected cell hypertrophies, becomes pale and 

 is filled with characteristic fine red granules (Schuffner's dots). The parasite 

 contains numerous, fine, highly motile grains of pigment : the rosette is 

 formed of 12 to 20 merozoi'tes : no crescent gametes are formed. 



3. Plasmodium preecox (Laverania malarice). The parasite of tropical, 

 pernicious, irregular, quotidian, malignant tertian and sestivo-autumnal 

 fevers. Young forms show very active amoeboid movement. The intra- 

 corpuscular parasites are so small that a single red cell can contain several 

 of them : the pigment grains are scanty, fine, and exhibit little motility : the 

 rosette is constituted of 6 to 15 small merozo'ites : the gametes are crescent- 

 shaped. The infected blood cells retain their natural size and assume a deep 

 copper colour. Parasites are only present in small numbers in the peripheral 

 blood but abound in the blood of the internal organs. The period of the 

 life-cycle is irregular and may be 24 or 48 hours or longer. 



Laveran holds that the parasites found in malaria are not different species 

 but merely varieties of the same species and distinguishes three such varie- 

 ties : Hcemamceba malarice var. parva, tertiana, quartana. Laveran has 

 seen changes taking place which he regards as a change from one variety to 

 another. Hcemamceba malarice parva corresponds to Laverania malarice, the 

 parasite of the pernicious and tropical fevers. In Laveran's opinion clinical 

 observation and microscopical investigation agree in showing that all forms 

 of malaria are clinically and setiologically the same disease. 



MetchnikofT and van Gorkone accept Laveran's views. According to van 

 Gorkone the variations in size, motility and morphological appearance are 

 due to the rapidity of growth of the Hsematozoa, which depends upon whether 

 the blood of the person infected is relatively favourable to their development 

 or not. 



The examination of mosquitos. 1 



Neveu-Lemaire recommends the following method. 



A few drops of chloroform are poured on the wool plug of the tube containing the 

 insect. When the mosquito is anaesthetized the legs and wings are pulled off and 

 the body laid on a slide. 



To withdraw the stomach fix the mosquito by pressing with a needle at the junction 

 of the thorax and abdomen, then with a second needle pull gently on the last two 

 segments of the abdomen, holding the needles horizontally : the stomach ruptures 

 at its junction with the oesophagus and is withdrawn with the intestines. It may now 

 be examined in one or other of the following solutions : 



1. Commercial formalin, 2 grams. 



Distilled water, . . iQQ 



2. Sodium chloride. .... j -59 grams. 

 The white of one egg. 



Distilled water, 250 



Filter before use. 



1 For a detailed account of the classification of mosquitos and of the methods of examina- 

 tion the reader is referred to Moustiques et maladies infectieuses by Ed. and t. Sergent. 



[A full account of the Structure and Biology of Anopheles is given by Nuttall and 

 Shipley in the Journal of Hygiene, vol. i. (Camb. Univ. Press) ] 



