46 Structure and Classification of Micro-organisms 



Order Coccidiida. Spherical or ovoid in form, without a free and 

 motile adult stage. Never ameboid. Sporulation takes place 

 within cysts formed while the organism is an intracellular parasite. 

 Genus Coccidium. 

 Genus Eimeria. 

 Order H^mospoeidiida. Sporozoa of small size living in the blood- 

 corpuscles or plasma of vertebrates. The adult form is mobile 

 and in some cases provided with myonemes. Reproduction by 

 endogenous or asexual sporulation, while in the host or by ex- 

 ogenous sporulation after conjugation. 

 Genus Plasmodium. 

 Subclass Neosporidia. Organisms that form sporocysts throughout life, 

 the entire cell not being used up in the formation of the spores. 

 Order Sarcospoeidia. The initial stage of the life history is passed 

 in the muscle cells of vertebrates. Form is elongate, tubular, 

 oval, or even spherical. Cysts have a double membrane, in which 

 reniform or falciform sporozoites are formed. 

 Genus Sarcocystis. 

 Genus Miescheria. 

 Genus Balbiania. 

 Subclass Haplosporidia. Spores provided with large round nuclei. No 

 polar capsules. 

 Genus Rhinosporidium. 

 Class Infusoria (Latin, infusus, to pour into. The organisms were given 

 this name because they were first found in infusions exposed to the 

 air). Protozoa in which the motor apparatus is in the form of cilia, 

 either simple or united into membranes, membranelles, or cirri. The 

 cilia may be permanent or limited to the embryonic stages. There 

 are two kinds of nuclei, macronucleus and micronucleus. Reproduc- 

 tion is effected by simple transverse division or by budding. Nutrition 

 is holozoic or parasitic. 

 Subclass Ciliata. Mouth and anus usually present. The contractile 

 vacuole often connected with a complicated system of canals. 

 Order HolOteichida. The cilia are similar and distributed all over 

 the body, with a tendency to lengthen at the mouth. Trichocysts 

 are always present, either over the whole body or in special regions. 

 Genus Colpoda. 

 Genus Chilodon. 

 Order Heterotrichida. Organisms possessing a uniform covering 

 of cilia over the entire body, and an adoral zone consisting of short 

 cilia fused together into membranelles. 

 Suborder Polytrichina. Uniform covering of cilia. 



Family Bursaridm. The body is usually short and pocketlike, 

 but may be elongated. The chief characteristic is the 

 peristome, which is not a furrow, but a broad triangular area 

 deeply insunk, and ending in a point at the mouth. The 

 adoral zone is usually confined to the left peristome edge or 

 it may cross over to the right anterior edge. 

 Genus Balantidium. 



Structure. — From the table it will at once be evident that the 

 protozoa form an extremely varied group, and that no kind of 

 descriptive treatment can be looked upon as adequate that does not 

 consider individuals. 



Cytoplasm. — In some of the smaller protozoa, and in certain stages 

 of others, the cytoplasm appears almost hyaline and structureless. 

 In most cases, however, it appears granular, and in the larger organ- 

 isms, such as ameba, it presents the appearance which some described 

 as granular, others, as frothy. The accepted theory of structure 

 teaches that the protoplasm is honeycombed or frothy, and that it is 



