The causation and prevention of malarial fevers : a statement of the results of researches drawn up for the use of assistant surgeons, hospital assistants and students / by S.P. James.

  • Sydney Price James
Date:
1903
Catalogue details

Licence: In copyright

Credit: The causation and prevention of malarial fevers : a statement of the results of researches drawn up for the use of assistant surgeons, hospital assistants and students / by S.P. James. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

    13/80 (page 5)
    of the parasite, three or four long filaments (flagella) [minrogametes] are suddenly protruded (PL I, 12). After lashing about for a few moments the flagella break off from the main body of the parasite and swim about in the fluid in the mosquito's stomach. They are the true male element in the sexual process. When one of them meets a female sexual form it enters it and fertilizes the true female element [macrogamete-] contained in it (PI. I, 14). After this act of fertilization has ' occurred, the female parasite acquires new characters. Changing from the shape of a sphere to that of an ovoid with a pointed end [ookmet] (PI. I, 15), it begins to move about, and making for the inner wall of the stomach of the mosquito it passes through the internal coats and comes to rest between the epithelial and muscular layers. Here it forms a capsule round itself and begins to grow, until in a few days it has attained a compara- tively large size (PI. 1,16). At this stage it is usually called a zygote, \pocy&t~\. By a process of division an enormous number of embryo parasites called sporozoites, elongated in shape and provided with a nucleus, are formed in the full grown zygote (PL I, 17, 18). After a time the capsule of the zygote bursts and the sporozoites are liberated into the lymph sinuses which surround the outer surface of the stomach. Thence they are conveyed by the circulation to the salivary glands, and penetrating the outer wall of the gland cells they come to rest in them and in the salivary duct, which has its external opening at the point of one of the piercing stylets of the proboscis which enter the skin in the act of biting. When the mosquito next bites a man it injects some of these sporozoites into his blood with the salivary or poison fluid.* Having got into the blood of man again the sporozoites after a certain time are found in the red blood corpu?cles as young parasites identical in all respects with those from which the cycle was commenced. These two cycles of the malaria parasite are represented as the male parasite has escaped from the red corpuscle it is able to throw out its flagella. This explanation would also account for the fact that phagocytic leucocytes do not attack sexual forms while they are in the blood of man, although as soon as they have escaped from the protecting envelope of the red corpuscles and changed into flagellated bodies, they. do so readily, in the same way as such leucocytes are able to attack the free spores of the asexual parasites as soon as they have escaped from the red cells. * It should be particularly noted that the tube down which the salivary Huid and sporozoites pass when injected into man, is quite separate from that through which blood is sucked up by the mosquito.