THE PROTOZOA 



153 



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 ( 

 parasitic in the blood of vertebrates. 



Example: Plasmodium. (Fig. 73.) 



24. Subclass 2. Neosporidia ( 



give rise to spores at intervals during active life. 



25. Order 



) Telosporidia 



) Sporozoa which 



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. Order 2. Sarcosporidia 

 ( ) Neosporidia 



usually parasitic in the muscles of 

 vertebrates. 



Example: Sarcocystis. (Fig. 75.) 

 The most common Sarcosporidia 

 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. Paramecium 

 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) Peritricha. 



30. Order 1. Holotricha ( ) Ciliata with cilia 

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



Fig. 74, 



Nosema. Longitudinal section of stomach of 

 honeybee showing infection with Nosema apis : 

 <>;>. 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 

 (6m) , 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.) 



