It was found that the life cycles of these parasites ran parallel with the clinical cycle of malarial disease. It was found that when the parasite had arrived at maturity the apyretic interval in an ague was about to conclude, and that when the parasite had arrived at the sporulating stage the patient had entered on the shivering stage of his fever. During that and the succeeding hot and sweating stage the spores had entered the red blood corpuscles, and when the parasite had ensconced itself in the red blood corpuscle and begun to grow, the fever had come to an end. It was found in tertian fever that the cycle of the parasite took forty-eight hours to complete, exactly the length of the cycle of the clinical phenomena. In quartan fever the cycle took seventy-two hours, exactly the length of the clinical cycle of that form of malarial disease. In the malignant or tropical fevers there was found to be a similar correspondence between the cycle of the parasite and the cycle of the disease. It was found that with each recurring paroxysm of fever there was a renewal of the life of the parasite, and that in this way the life of the parasite was continued from period to period and from cycle to cycle for weeks or even, especially in the case of quartan malaria, for months. Now this explains very well the way in which the malaria parasite contrives to maintain its existence in the human body, but it does not explain how it passes from host to host, neither does it explain certain appearances that Laveran and everybody else who has studied the subject have witnessed. In malarial blood you sometimes see that peculiar body, the flagellated body, which I have already alluded to as consisting of a sphere surrounded by from one to six or seven long tentacles or arms in a state of continual agitation. Neither does it explain the peculiar crescent-shaped body which also so pointedly arrested Laveran’s attention.... Golgi’s scheme leaves the passage of the parasite from host to host and also the nature of these two bodies unexplained. What relation have these two bodies to the life of the parasite? Their nature and purpose do not receive any illumination from Golgi’s theory. You will find in all forms of malarial infection, if you look enough, the flagellated body; but, strange to say, you will not find it in malarial blood immediately after it is withdrawn from the body. It is only after an interval of minutes, perhaps a quarter of an hour, after the blood is withdrawn that these flagellated bodies appear. Whence do they come? If you make a preparation of malarial blood from a patient by pricking the finger and spreading a little of the blood on a slide, fixing it immediately with heat or alcohol and staining it, you will never see any of these flagellated organisms. But if the slip be kept moist and in a warm temperature for half an hour and then stained, the flagellated bodies will be seen, proving that they develop only after the escape of the