CHORD ARIA. 



[ 141 ] 



CHYLAQUEOUS. 



water. On cutting off the tail, it may then 

 be pressed out by gently scraping along its 

 course from the end of the tail, or from the 

 head towards the woimd. It is a beautifully 

 delicate structure, and closely resembles in 

 appearance a piece of vegetable cellular tissue. 



BiBL. KoUiker, Mikrosk. Anat. ii. p. 346 ; 

 Schwann, Ueber die Einstim., Sfc. {Sydenh. 

 Soc.) ; Stannius, Vergl. Anat. 



CHORDARIA, Ag.— A genus of Chorda- 

 riaceae (Fucoid Algse), remarkable for the 

 solidity of the cellular texture of their fili- 

 form fronds. The axis and branches are 

 composed of a central mass of longitudinal 

 cells, upon which stand horizontal clavate 

 filaments, formed of a row of beaded cells, 

 constituting a distinct peri])heral layer, which 

 gives a velvety texture and shmy character 

 to the surface. The so-called spores attached 

 to the horizontal filaments are oosporanges, 

 and discharge zoospores when mature ; tri- 

 chosporanges have not yet been observed. 

 C. jiagelliformis, MiilL, is common on rocks 

 and stones between tide-marks. 



BiBL. Hai'vey, Br. Mar. Alg. pi. 10 A.; 

 Phyc. Brit. pi. Ill; Thuret, Ann. des Sc. 

 nat. 3 ser. xiv. 237- 



CHORDARIACEJE.— A family of Fucoid 

 Algae. Olive-coloured sea-weeds with a 

 gelatinous or cartilaginous, branching frond, 

 composed of vertical and horizontal filaments 

 interlaced together; the oosporanges andtri- 

 chosporanges attached to the filaments 

 forming the superficial layers of the frond. 

 Br. genera : 



1. Chordaria. Axis cartilaginous, dense ; 

 filaments of the cncumference unbraiiched. 



2. Mesogloia. Axis gelatinous, loose ; 

 filaments of the circumference branching. 



BiBL. Harvey, Br. Marine AlgcB; Thm'et, 

 Ann. des Sc. nat. 3 ser. xvi. p. 5, &c. See 

 also the genera. 



CHOROID MEMBRANE. See Eye. 



CHROMATE OF LEAD (neutral).— Is 

 one of the best materials for colom-ing size 

 in injections. See Injection. 



CHROMIC ACID.— May be prepared 

 b\ adding gradually from 120 to 150 parts, by 

 volume, of pure concentrated sulphuric acid 

 to 100 parts of a cold saturated solution of 

 bichromate of potash. The crystals of the 

 acid separate as the solution cools. The 

 mother-liquor should be pom-ed off, and the 

 crystals ch-ied upon a tile ; they may be 

 purified by re-crystallization from solution 

 in water. Or, by adding two parts of concen- 

 trated sulphm-ic acid to about one of diy 

 chromate of lead, and setting aside the thin 



paste for twelve hours. On the addition of 

 water, the insoluble sulphate of lead subsides. 

 The supernatant liquid is poured off and 

 boiled do\Mi in a retort until the acid sepa- 

 rates on cooling. The crystals should be 

 di'ied on a tile and further purified as above. 



Chromic acid is readily decomposed by 

 organic matter, as dust, &c., and should 

 therefore be preserved in a well-stoppered 

 bottle. Its aqueous solution, which should 

 be of a pale yellow coloiu', is used for 

 hardening and preserving nervous and mus- 

 cular tissues, &c. It should be prepared 

 when required. 



CHROOCOCCUS, Nag. See Proto- 

 coccus. 



CHRYSIMENIA, J. Ag.— A genus of 

 Lam'enciaceae (Florideous Algae). 



C. clavellosa is a rare sea- weed 3 to 12" 

 high, forming a feathery frond, composed of 

 a branched, tubular, long, not constricted or 

 chambered cellular structure, filled with a 

 watery juice. The spores are angular, and 

 are contained in dense tufts in ceramidia 

 borne on the sides of the branchlets. The 

 tetraspores are 3-partite and immersed in 

 the branchlets. 



BiBL. Hai-vev, Br. Mar. Alg. pi. 13 A. ; 

 Phyc. Brit. pi. Il4. 



CHTHONOBLASTUS, Kiitz. See Mi- 



CROCOLEUS. 



CHYDORUS, Leach {Lynceus, Miill., in 

 part). A genus of Entomostraca, of the 

 order Cladocera, and family Lynceidae. 



Char. Nearly spherical; beak very long 

 and sharp, cm'ved downwards and forv\'ards ; 

 inferior antennae ver}'^ short. 



C. sphcericus (PI. 15. fig. 7)- Shell smooth ; 

 olive-green. Found in ponds and ditches. 



C. globosus. Shell more rounded than in 

 the last, and nearly six times larger ; ante- 

 riorly reddish, with circular striae and nume- 

 rous black spots; aquatic; less common 

 than the former. 



BiBL. Baird, Brit. Entom. p. 125. 



CHYLAQUEOUS orchylo-aqueoushquid 

 and svstem. 



In the Invertebrata, two distinct kinds of 

 nutrient liquids exist. In some classes of 

 this subkingdom, these two hquids coexist 

 in the same organism, though contained in 

 distinct systems of conduits; while in others 

 they become united into one. Dr. T. Wil- 

 liams distinguishes these two kinds of liquid 

 as the blood proper or true blood, and the 

 chylaqueous liquid. The former is always 

 contained in definitely organized (walled) 

 blood - vessels, and has a determinate 



