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tissues, and so at this stage it is also called the encysted 
zygote or Oocyst. Growth proceeds, and signs of 
division into several masses appear in the protoplasm. 
These masses are termed Sporoblasts. Then we reach 
the stage of large oocyst (with sporoblasts), and by this 
time the masses of the sporoblast have undergone 
division into a number of fine curved thread-like bodies, 
the Sporozoits , so that eventually the large cyst is almost 
entirely filled with sporozoits. The capsule of the 
cyst eventually ruptures, and the sporozoits pass from 
the tissues of the stomach to the thorax, being found 
at first amidst the muscles, but eventually all collected 
in the salivary glands. From here they are injected 
into the blood by the mosquito, and they then attach 
themselves to and penetrate the red cells (as has been 
actually observed under the microscope by Schaudinn), 
producing a new infection. 
We may briefly summarize these various steps :— 
1. Microgametocyte, and macrogamete in blood. 
2. Development of microgametes = flagellation, 
on the slide and in nature in stomach of an Anopheline. 
3. Fertilization of the macrogamete producing 
a zygote or copula, on the slide and in nature in the 
mosquito. 
4. Vermiculus or ookinet. Only in mosquito 
stomach. 
5. Oocyst. In stomach wall. 
6. Medium or large oocyst* with sporoblasts. 
7. Sporozoits. (i) In the large cysts, (2) in 
salivary glands. 
The sexual cycle is known also as sporogony or 
amphigony, while the asexual cycle is known as schizo¬ 
gony or monogony. These two cycles and their 
* Not uncommonly stages 4-6 are also called zygote. 
