204 INSECTS 



spores are entering new blood-corpuscles. In other words 

 the "chills" and "fever" merely emphasize the period 

 at which the parasite sporulates, and the ill effects of 

 malaria are due to the gradual destruction of the red 

 blood-cells. 



If some of this infested blood be drawn from a pa- 

 tient and injected into the circulation of a healthy indi- 

 vidual, a new case of malaria will result; but in no other 

 way can there be a direct infection from one individual 

 to another. Normally this reproduction by means of 

 spores continues in an infested individual for some time 

 and then, in addition to the spores, special cells develop 

 which, when liberated into the blood-serum, make no 

 attempt to enter new blood-corpuscles. These are the 

 "gametes," of two types, differing a little in size and 

 form and termed respectively "micro-" and "macro- 

 gametes. " They undergo no change in the human body 

 and may remain in that stage for an indefinite period, 

 even when the active reproduction of the Plasmodia 

 has been checked and the patient is apparently well. 

 Taken from the human body by any sort of blood- 

 sucker or even drawn on a properly prepared slide, 

 further development takes place. From the micro- 

 gametes slender, whip-like processes are produced, 

 known as "flagellae," and these break off and represent 

 the male element that unites or conjugates with the 

 large unaltered " macrogamete " representing the female 

 element. At this point development stops unless the 

 blood is in the stomach of a mosquito belonging to the 

 genus Anopheles. If it is not only Anopheles, but a 

 member of the right species, the conjugated gamete 

 elongates and becomes a "vermicule" which bores into 

 the tissue of the mosquito stomach, increases in size and 

 gradually works its way to the outer surface where it 

 forms a little lump or protuberance, now known as a 



