CHI-SQUARE TEST 



chi-square test — A statistical significance test 

 based on frequency of occurrence; it is appli- 

 cable botli to qualitative attributes and quanti- 

 tative variables. Among its many uses, the 

 most common are tests of hypothesized proba- 

 bilities or probability distributions (goodness of 

 fit), statistical dependence or independence 

 (association), and common population homo- 

 geneity). (5) 



chitin — A nitrogeneous carbohydrate derivative 

 forming the skeletal substance in arthropods. 

 (26) 



chiton — One of a class (Amphineura) of flattened 

 mollusks protected either by calcareous 

 spicules or plates. 



chlorine equivalent — Original definition of 

 chlorinity. It represents the total amount of 

 chlorine, bromine, and iodine in grams per kilo- 

 gram of sea water, with the assumption that 

 the bromine and iodine have been replaced by 

 chlorine. Chlorine equivalent is dependent on 

 changes in atomic weights, whereas chlorinity 

 is independent of such changes. (54) 



chlorinity — (symbol CI). A measure of the 

 chloride content, by mass, of sea water (grams 

 per kilogram of sea water, or per mille) . Orig- 

 inally chlorinity was defined as the weight of 

 chlorine in grams per kilogram of sea water 

 after the bromides and the iodides had been re- 

 placed by chlorides. To make the definition 

 independent of atomic weight, chlorinity is now 

 defined as 0.328523.3 times the weight of silver 

 equivalent to all the halides. 



Because of the Law of Constancy of Relative 

 Proportions the amount of chlorinity in a sea 

 water sample is generally used to establish the 

 sample's salinity. By using normal water as 

 a comparison standard, Knudsen burettes and 

 pipettes for the analysis, and Knudsen's 

 Tables to compute the results, determinations 

 as accurate as those of a time-consuming gravi- 

 metric analysis can be made with a rapid titra- 

 tion of the sea water against silver nitrate solu- 

 tion, employing potassium chromate or other 

 suitable indicator for the end-point. 



chlorophyll — A group of green pigments, identi- 

 fied as fl, &, and c, whicli occur chiefly in bodies 

 called chloroplasts and are active in photo- 

 synthesis. The concentration of each of these 

 pigments has been employed as a means of 

 estimating the rate of photosynthesis (primary 

 production) or as an index of the standing crop 

 of plant forms. 



chloroplast — The green pigmented body or bodies 

 within the cells of green algae. (13) 



chlorosity— The chlorine content of one liter of 

 sea water. It is equal to the chlorinity of the 

 sample times its density at 20°C. (5) 



chlorosity factor — The ratio between the various 

 substances in sea water and the chlorosity. It 

 is obtained by dividing the concentration of the 

 substance in milligram-atoms per liter by the 

 chlorosity. (54) 



cHiop — (or wind chop). The short-crested waves 

 that may spring up quickly in a fairly moderate 

 breeze and break easily at the crest. (61) 



chopping sea — See choppy sea. 



choppy sea — (also called chopping sea, cockling 

 sea) . Short, rough waves tumbling with a short 

 and quick motion. (73) 



chordate — One of a phylum (Chordata) of ani- 

 mals which possess a notochord (a middorsal 

 cylindrical rod), a series of paired gill slits, 

 both of which features are present only in the 

 embryo of air-breathing members, and a dorsal 

 central nervous system. Representative chord- 

 ates are the tunicates, fishes, and mammals. 



chuck — A narrow passage or strait swept by 

 tidal currents, also applied to the tidal current 

 itself. (2) 



ciguatera — An intoxication in humans resulting 

 from the ingestion of various tropical reef and 

 insliore fishes and possibly certain invertebrates. 

 The most common symptoms are tingling and 

 numbness of the lips, tongue, hands, and feet, 

 confusion of sensations of heat and cold, nausea, 

 diarrhea, joint and muscular pain, burning uri- 

 nation, inability to coordinate voluntary muscu- 

 lar movements, and difficult breathing. The 

 fatality rate is about 7 percent. The fishes in- 

 volved usually are large carnivorous forms such 

 as barracudas, snappers, groupers, and jacks. 

 Many other common food fishes have been impli- 

 cated in sporadic outbreaks of this type of poi- 

 soning, as well as certain marine snails and sea 

 urchins. 



cilia — Hairlike processes of cells, which beat 

 rhythmically and cause locomotion of the cells 

 or produce currents in water. 



cinders — See scoria, lapilli. 



cinerite — Sedimentary material consisting of vol- 

 canic cinders. (2) 



circle of longitude — See parallel of latitude. 



circulation — 1. The flow or motion of a fluid in 

 or through a given area or volume. 



2. A general term describing water current 

 flow within a large area; usually a closed cir- 

 cular pattern such as in the North Atlantic,. 

 Mediterranean, etc. 



cirripede — See barnacle. 



cirrus — 1. One of the appendages of barnacles; 

 one of the filamentous respiratory and tactile 

 appendages of annelids. (26). 

 2. Also, a principal cloud type. 



cladoceran — tSee water flea. 



clam — A member of any one of several families 

 of generally edible bivalves, the majority of 

 which burrow into mud or sand bottoms. 



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