Tomite The stage in the life cycle of some cil- 

 iates which results from repeated divisions 

 of a larger cell without any cell growth, such 

 that the eventual cell is considerably smaller 

 than the original cell. 



Transverse cirri A group of five to many rel- 

 atively large cirri near the posterior end of the 

 body on the ventral midline (see Fig. 1). 



Trophont The normal feeding adult stage of 

 the life cycle of the ciliate. 



Undulating membrane A compound ciliary or- 

 ganelle consisting of one or several closely 

 set rows of cilia usually placed longitudinally 

 along the right edge of the buccal cavity where 

 it functions in feeding (see Fig. 1). 



Vestibidum A depression of the cell surface 

 bearing simple cilia used in feeding (see Fig. 

 5). 



TECHNIQUES 



Ciliated Protozoa occur in a wide variety of 

 environments, wherever there are sufficient nu- 

 trients, moisture, and appropriate microhabitats. 

 Ciliates can be observed easily by examining col- 

 lections from tidal pools on rocky shores and 

 marshes. They are particularly abundant both 

 intertidally and subtidally in interstices among 

 sand grains. Ciliates also reach great numbers 

 among fine filaments of some green algae (i.e., 

 Cladophora and Vaucheria) . Wide-mouthed 

 glass jars (100-2,000 cm') make excellent con- 

 tainers for nonquantitative collecting of ciliates 

 from such habitats. Add enough substratum to 

 fill the container about one-third and an equal 

 amount of water. 



As soon as you can do so conveniently, distrib- 

 ute some of the material among several finger- 

 bowls with varying proportions of substratum 

 and water, to increase the variety of possible 

 ciliates. 



Ciliates may be concentrated from field sam- 

 ples by filtration, moderate centrifugation, and 

 other separation methods such as electromigra- 

 tion (Hair.ston and Kellermann, 1964) and ex- 

 traction with seawater ice (Uhlig, 1965). 



To remove ciliates from interstices of mats of 

 vegetation, filter them through two-ply cheese- 

 cloth, then concentrate them with Whatman ^l 

 filter paper. As this will retain all but the small- 

 est organisms (less than 15 /um width), the con- 

 tents of the filter can be removed to a petri dish 



for examination. Series of filters containing 

 nylon gauze of known mesh size (Nytex) allow 

 separation of most metazoans and larger frag- 

 ments of debris from the water containing cil- 

 iates. 



Moderate centrifugation (5-20 min at 2,500 

 rpm) can also help to concentrate many ciliates. 

 The speed or duration of centrifugation can be 

 varied to correspond with the size and fragility 

 of the organism. 



Although most ciliates undergo sexual pro- 

 cesses, they normally reproduce asexually and 

 hence can be cultured to obtain additional spec- 

 imens for further study. Cultures can be main- 

 tained in suitable covered containers. Addition 

 of simple nutrients (i.e., rice grains, wheat 

 grains, split peas, short dried lengths of grass 

 stems) will increase the growth rate of the mi- 

 croflora on which many ciliates feed. 



In addition to these simple methods there are 

 many inorganic solutions and complex culture 

 media available for maintaining mixed cultures 

 of ciliates (.see Kudo, 1966). 



The couplets in this key are based on living 

 material and assume sufficient microscopic reso- 

 lution to allow visibility of the structures de- 

 scribed. As the organisms are small, they must 

 be examined with great care, and since living 

 ciliates often move too rapidly to allow identi- 

 fication, it is necessary to slow them down. This 

 is accomplished by removing sufficient water 

 from the edge of the preparation to squeeze the 

 animal gently between the slide and coverslip. 

 As this may cause distortion and death of the 

 cell, studies on living specimens should be aug- 

 mented with stained preparations. 



Observations of living individuals of ciliates 

 can often be supiilemented by appropriate fix- 

 ation and staining procedures that allow reso- 

 lution and diff'erentiation of features diflicult to 

 see in life (i.e., nuclei, details of the cilia in the 

 region of the c\'tostome). The simplest c>i;o- 

 logical methods easily employed in marine cil- 

 iates are variations of the iron hematoxylin 

 method, the Feulgen nucleal reaction (both de- 

 scribed by Kudo, 1966), and the nigrosin-mer- 

 curic chloride-Formalin technique (NMF meth- 

 od) (see Borror, 1968a, 1969). 



The NMF method can be applied to fresh ma- 

 terial rapidly, giving permanently stained cells 

 in 10 or 15 min. The stain-affixative is mixed 



