PROTOZOA 35 



Order 2. Coccidiida 



The Coccidiida (Gr. kokkos, a berry) are extremely small 

 Sporozoa, spherical or ovoid, and live within the cells of the 

 higher animals, particularly in the liver and the intestine. There 

 each individual secretes a cyst about itself, and afterward, the 

 contents of the cyst divides into spores, each of which gives 

 rise to crescentic young (Fig. 15, 3). These parasites are of 

 importance to physicians, as they sometimes occur in man and 

 produce serious diseases. 



Order 3. Myxosporida 



The Myxosporida (Gr. fiv^a, mucus) differ from the other 

 Sporozoa in being amoeboid. They exhibit a clear ectosarc and 

 a granular entosarc, the latter containing many nuclei (Fig. 

 15, 4). Reproduction is by spore formation attending encyst- 

 ment ; both the method of formation and the spores themselves 

 are rather complex. The Myxosporida are parasitic for the most 

 part on fishes, and are found in the skin and in many of the 

 internal organs. 



Order 4. Sarcosporida 



The Sarcosporida (Gr. o-dp!;, flesh) occur in the voluntary 

 muscles of some of the higher animals, where they exist as 

 elongated cvsts. The walls of these cysts are radially striated, 

 and contain a granular mass of protoplasm, which eventually 

 forms a number of spores, and these give rise to numerous 

 crescentic young. One of the most common representatives o\ 

 the order is Sarcocystis (Fig. 15, 5), which is found in the pig; 

 it does not appear to affect the health of its host. 



Order 5. Haemosporida 



The Haemosporida (Gr. al/ia, blood) are minute animals 

 living within the blood-cells, especially the red blood-cells, of 

 higher animals. The young individuals enter the cells, grow to 

 maturity, deriving their nourishment from the cell they inhabit, 

 and then break up into a number of sporelike bodies or young, 

 which pass into other blood-cells (Figs. 15 and 16). These animals 

 are of great importance to the ph) sician, for they are the para- 

 sites to which the malarial or intermittent fevers are due. 



