154 



General Biology 



Monocysts ( ) may be found in the seminal 



vesicles of almost every earth-worm ; Gregarina is a common parasite of 

 the cockroach ; and Porospora gigantea, which reaches a length of two- 

 thirds of an inch, inhabits the alimentary canal of the lobster. 



22. Order 2. Coccidiidea ( ) Telosporidia simple 

 in structure ; trophozoite is a minute intracellular parasite. 



Example: Coccidium. (Fig. 72. ) 



Members of this order are sometimes found in the liver and intestine 

 of man and other vertebrates, and in Arthropoda and Mollusca. 



23. Order 3. Haemosporidia ( ) Telosporidia 

 parasitic in the blood of vertebrates. 



Example: Plasmodium. (Fig. 73.) 



24. Subclass 2. Neosporidia ( ) Sporozoa which 

 give rise to spores at intervals during active life. 



25. Order 1. Myxosporidia 

 ( ) Neosporidia 

 with ameboid intercellular tropho- 

 zoite. 



Example: Nosema. (Fig. 74.) 

 The Myxosporidia are parasitic 

 especially in Arthropoda and fish, 

 frequently causing serious epidemics 

 in aquaria. Nosema bombycis pro- 

 duces the silkworm disease, pebrine. 



26. O r d e r 2. Sarcosporidia 

 ( ) Neosporidia 

 usually parasitic in the muscles of 

 vertebrates. 



Example: Sarcocystis. (Fig. 75.) 

 The most common Sarco- 

 sporidia are Sarcocystis miescheriana 



in the muscle of the pig; S. muris, in that of the mouse; S. lindemanni, 



rarely occurring in the muscles of human beings. 



27. The Infusoria ( ) are protozoa with cilia 

 which serve as locomotor organs and for procuring food. Paramoecium 

 is a typical member of the class. There are two subclasses, (1) Ciliata, 

 and (2) Suctoria. 



28. Subclass 1. Ciliata ( ) Infusoria with cilia 

 in the adult stage, a mouth, and usually undulating membranes or cirri. 

 Many ciliates are confined to fresh water, others occur either in fresh or 

 salt water, and still others are parasitic in Metozoa. 



29. There are four orders: (1) Holotricha, (2) Heterotricha, (3) 

 Hypotricha, (4) Petritricha. 



30. Order 1. Holotricha ( ) Ciliata with cilia 

 all over the body and of approximately equal length and thickness. 



Nosema. Longitudinal section of stomach of 

 honeybee showing infection with Nosema apis: 

 ep, Epithelial portion, containing spores of the 

 parasite stained black. (The younger para- 

 sites, not differentiated so easily by staining, 

 are not shown; they are found toward the base 

 .of the cells reaching the basement membrane 

 (bm), but do not extend beyond it. Younger 

 spores sometimes show an unstained area at 

 one end and occasionally at both ends. m, 

 muscular portion of stomach wall showing an 

 outer and an inner longitudinal muscular layer 

 and a middle circular one. (After G. F. White, 

 U. S. Dept. of Agriculture Bulletin No. 780.) 



