366 POPULAR SCIENCE MONTHLY. 



that they are not directly concerned in th^ production of the phenomena 

 which constitute a malarial attack and that the administration of 

 quinine has no influence in causing them to disappear from the blood. 

 On the other hand, the febrile phenomena are directly associated with 

 the appearance of the amoeboid form of the parasite in the interior of 

 the red blood corpuscles and the administration of suitable doses of 

 quinine has a marked effect in causing these amceba-like micro-organ- 

 isms to disappear from the blood. 



These crescentic bodies are not found in the benign tertian and quar- 

 tan intermittent fevers, but are characteristic of the malignant forms of 

 malarial infection, including the so-called asstivo-autumnal fever. In 

 these forms of fever they are not seen at the outset of the attack, and 

 they have no direct influence upon the course of the fever. A week 

 usually elapses between the first appearance of the amoeboid form of the 

 parasite and that of these crescentic bodies. They are often found in 

 the blood some time after all symptoms of fever have disappeared, and 

 are associated with the malarial cachexia which follows an attack of 

 aestivo-autumnal fever. When blood containing these crescents is in- 

 gested by a mosquito of the genus Anopheles the following very remark- 

 able transformations occur: Some of the crescents are transformed into 

 hyaline flagellate bodies having active movements; others are changed 

 into granular spheres. The flagella break away from the hyaline bodies 

 and, approaching the granular spheres, appear to seek energetically to 

 enter these bodies. A minute papilla is given off from the surface of 

 the sphere, seeming to be projected to meet the attacking flagellum. At 

 this point, one of the flagella succeeds in entering the sphere, causing an 

 active movement of its contents for a brief time, after which the flagella 

 disappear from view, and the contents become quiescent. This is no 

 doubt an act of impregnation. After a time the impregnated granular 

 sphere alters its shape, becoming oval, and later vermicular in form. 

 The pigment granules are now seen at the posterior part of this body, 

 which, after the changes mentioned, exhibits active movements. It is 

 believed that this motile vermicular body penetrates the wall of the mos- 

 quito's stomach. Here it grows rapidly and, after a few days, may be 

 seen projecting from the surface as a spherical mass. In the meantime 

 the contents are transformed into spindle-shaped bodies (sporozoites) 

 which are subsequently set free by the rupture of the capsule of the 

 mother cell. According to Manson, these spindle-shaped bodies pass 

 from the body cavity of the mosquito, probably by way of the blood, to 

 the three-lobed veneno-salivary glands, lying on each side of the fore 

 part of the thorax of the insect. "These glands communicate with the 

 base of the mosquito's proboscis by means of a long duct along the 

 radicles of which the clear, plump cells of the gland are arranged. The 

 sporozoites can be readily recognized in many, though not in all, of the 



