The Protozoa 53 



Subclass Haplosporidia. Spores provided with large round 



nuclei. No polar capsules. 

 Genus Rhinosporidium. 



Class Infusoria (Latin, injusus, 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. Reproduction is 

 effected by simple transverse division or by budding. Nutri- 

 tion is holozoic or parasitic. 



Subclass Ciliata. Mouth and anus usually present. The 

 contractile vacuole often connected with a complicated sys- 

 tem of canals. 



Order HOLOTRICHIDA. 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. 

 " 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 Bursarida. The body is usually short and pocket- 

 like, 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 organisms, 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 filled 

 with endless chambers in which its enzymes and other 

 active substances, etc., are stored up and its functions car- 

 ried on. 



In addition to these chambers, which are minute and of 

 uniform size, there are larger spaces called vacuoles, some 

 of which are the result of temporary conditions accumu- 

 lations of digested but not yet assimilated food, etc.; but 



