22 TROPICAL MEDICINE AND HYGIENE 



themselves from the mass of residual protoplasm in 

 which the pigment is included, and swim freely in the 

 blood plasma. They have been seen to fertilize the 

 female or macrogamete. The residual protoplasm and 

 pigment are swallowed by surrounding leucocytes, 

 usually the large mononuclear ones, rarely the poly- 

 morphonuclear. The pigment is not digested by these 

 leucocytes, but is carried by them to the spleen or liver, 

 and there deposited in cells and connective tissue. 



Parasites in all stages in benign tertian and quartan 

 malaria may be seen in a series of consecutive examina- 

 tions. The sporulating forms are not so numerous in 

 the peripheral blood as the younger forms, as a con- 

 siderable proportion of the corpuscles containing the 

 full-grown and sporulating forms seem to be detained 

 in the splenic sinuses. At any one time either all the 

 parasites are about the same age, or those of one set 

 are twenty-four hours older or younger than the others. 

 It is very unusual to find parasites in the intermediate 

 stages of growth ; it follows from this that the sporulation 

 of a large number of the parasites is nearly synchronous. 



If there is only one generation the successive sporula- 

 tions are at intervals of forty-eight hours in the tertian 

 and seventy-two in the quartan. If there are two genera- 

 tions, in tertian they will sporulate on successive days, 

 but the sporulation of the individuals of each generation 

 is synchronous. 



In quartan there may be at the same time, one, two, 

 or three generations. Where there are three they will 

 sporulate on three consecutive days. Where there are 

 two generations, on two consecutive days with one day's 

 interval. 



Parasites in Subtertian Malaria. The results of the 

 examination of fresh blood in subtertian fever (malignant 

 tertian) differ in important points. 



In the great majority of cases during the febrile period 

 only small parasites free from pigment are found. These 

 are usually actively amoeboid, but the changes in shape 



