PROTOZOA 



33 



Mediterranean, in Virginia and Maryland, in the Barbados, and 

 most extensively in the Nicobar Islands, where they contribute 

 rock formations from three hundred to six hundred meters thick. 



CLASS II. SPOROZOA 



The Sporozoa (Gr. airopos, seed, and %wov, animal) constitute 

 a small group of parasitic Protozoa, all living within the cells or 

 the cavities of other animals, and in this respect they differ 

 from all other classes of Protozoa ; for though there are some 

 parasites in each class, all the members of the Sporozoa are 

 parasitic. They reproduce exclusively by spore formation, and 

 from this fact derive their name. This class may be divided 

 into five orders. 



Order i. Gregarinida 



gregarius, gregarious) include the 

 They are generally more or less 



-mi 



A B C 



14. Monocystis agilis. A, B, different shapes 

 The members Of assumed; C, cyst containing spores. (From Parker 

 and Hasweli's Manual.) 



The Gregarinida (Lat. 

 largest of the Sporozoa. 

 elongated, and possess a 

 granular entosarc contain- 

 ing a single nucleus but no 

 vacuoles, and a clear ecto- 

 sarc with an outer cuti- 

 cula, a delicate membrane 

 through which fluids pass 

 to nourish the protoplasm FlG 

 within. 



this class are divided into 

 two groups, the one represented by Monocystis (Fig. 14), which 

 occurs in the male reproductive organs of the earthworm, the 

 other known as Gregarina or Porospora (Fig. 15), which lives in 

 the intestines of various insects, the lobster, crayfish, and similar 

 animals. Monocystis is like the type just described. Repro- 

 duction begins by the formation of a cyst, which may contain 

 one or two individuals. Within the cyst a large number of 

 spindle-shaped bodies, the so-called spores, are formed by the 

 division of the nucleus or nuclei, and then the contents of each 

 of these spores divides into a number of crescentic bodies, each 

 of which becomes a new individual. Gregarina may be dis- 

 tinguished from Monocystis by the fact that the body is divided 



