OXYTRICHA. 15 



Make a drawing of an expanded individual and a sketch to 

 show the condition when contracted. (Minchin, p. 434; Doflein, 

 p. 1144.) 



9. Study, by means of finely powdered carmine, the vortex 

 currents set up by the cilia. Note how the particles are collected 

 in the gullet, and at intervals are forced in rounded masses into 

 the endoplasm to form gastric vacuoles. Is there a definite 

 circulation in the endoplasm ? 



10. Endeavor to find several stages of reproduction by divi- 

 sion. 



Large fresh-water species of Vorticella are preferable for 

 study, but marine species may be substituted when necessary. 

 If time and material permit, study Lichnophora, a marine peri- 

 trichous form parasitic on Crepidula. (See Calkins' Protozoa, 

 p. 203.) 



Schroder: Beitrage zur Kenntnis von V. monilata. Arch. f. Protistenk., 7, 

 1906. 



OXYTRICHA. 



Infusoria belonging to the genus Oxytricha, or the genera 

 Stylonychia, Pleurotricha, Euplotes, etc. (Doflein, p. 147), 

 may be used for the following study. These forms belong 

 to the order Hypotrichida. Hypotrichous forms are among 

 the most highly organized of the class Infusoria, as well as of 

 the entire phylum of Protozoa, and present a complexity of 

 structure and function which probably is not exceeded within 

 the limits of a single cell elsewhere in the animal series. 



1. In an animal which is becoming quiet, note the mode of 

 locomotion, the shape of the body, the buccal groove, the con- 

 tractile vacuole, etc., as in other forms studied. Compare the 

 dilation with that of other forms. Refer to Calkins' Protozoa, 

 Fig. 98, and understand the relation of cirri, membranelles, etc., 

 to cilia. 



Draw, showing the structure in detail. 



2. Run some methyl-green under the cover-glass. What 

 is the shape of the macronucleusf The shape varies consider- 

 ably in the different genera. Is it possible to distinguish the 

 micronuclei? 



