CEMENTS. 



CEPHALOPODA. 



Sealing-ioax varnish. Prepared by add- 

 ing enough spirit of wine to cover coarsely- 

 powdered sealing-wax ; and digesting at a 

 gentle heat. 



Shell-lac varnish. Prepared in the same 

 manner as sealing-wax varnish, shell-lac 

 being substituted for the sealing-wax. 20 

 drops of castor-oil to the ounce is an im- 

 provement. 



White hard varnish consists of gum san- 

 darac dissolved in spirit of wine, and mixed 

 with turpentine varnish. 



Bismuth-cement. Made by thickening a 

 solution of mastic in chloroform with sub- 

 nitrate of bismuth. 



India-rubber and asphalt. Made with 

 India-rubber 30 grs., asphalt 4 oz., mineral 

 naphtha 10 oz. Dissolve the caoutchouc in 

 the naphtha, then add the asphalt, and heat 

 if necessary. 



White lead mixed with drying linseed- 

 oil, and oil of turpentine (white paint). 



Wheat-paste should have a few drops of 

 some volatile oil, or carbolic acid added to 

 it. 



Gum-arabic dissolved in water, with a 

 small quantity of glycerine, and a few drops 

 of volatile oil. 



Zinc-cement. This is made with oxide of 

 zinc, drying oil, Dammara-resin, and ben- 

 zoline. 



French cement, is made by melting India- 

 rubber scraps in a covered iron pot. When 

 quite liquid, lime previously slaked by ex- 

 posure to the air and in fine powder, is 

 added in small quantities at a time. When 

 moderately thick, it is removed from the 

 fire, well beaten in a mortar, and moulded 

 in the hands until of the consistence of 

 putty. It is useful for mounting large mi- 

 croscopic preparations &c. A drawn-out 

 thread of this is pressed upon the top of the 

 cell j the object and liquid are then added, 

 and the cover pressed upon the cement, 

 beginning at one side, so that the super- 

 fluous liquid may escape. 



A number of other cements, applicable to 

 various purposes, are described by Beale in 

 How to Work &c. p. 54. The method of 

 using these cements is treated of under 

 PRESERVATION. 



The varnishes should be kept in wide- 

 mouthed capped bottles, or in bottles accu- 

 rately closed by a cork, in the under part of 

 which a camel's hair pencil is inserted. 



A black colour may be imparted to any of 

 the varnishes, by mixing them with lamp- 



black ; or any colour, by adding correspond- 

 ingly coloured sealing-wax. 



They should all be old, or kept some time 

 before use. 



CENAN'GIUM, Fries. A genus of 

 Phacidiacei (Ascomycetous Fungi) grow- 

 ing upon dead twigs, bursting through the 

 bark in the form of little cups or hollow 

 papillae. Tulasne has recently made some 

 interesting observations upon this genus, 

 and shown that the plants present two or 

 even three kinds of reproductive bodies, 

 asci with spores, and also spermogonia and 

 pycnidia with spermatia and stylospores. In 

 C. Cerasi) Fr., the pycnidia are minute 

 tubular bodies upon the same stroma as the 

 young cupules or asciferous cups. They have 

 been described as species of SpJueria and as 

 imperfect cupules of C. Cerasi; but their 

 walls are lined with basidia, producing 

 short-stalked stylospores, which are linear 

 and flexuous, and very large, viz. about 

 1-500" long; they exhibit three transverse 

 septa. In this species the pycnidia are 

 found in groups, and sometimes become 

 confluent. In C. Fraxini, Tul. (PI. 26. 

 fig. 17), the pycnidia contain not only stylo- 

 spores at the base of the cavity, but around 

 the upper part are found spermatia seated 

 on branched articulated filaments. These 

 organs, however, are not regularly co- 

 existent, but occasionally occur alone in a 

 pycnidium; and sometimes the spermatia 

 occur even in the asciferous cupules. The 

 asci in the cupules of C. Franyulce line the 

 bottom of the cups, and are mixed with 

 paraphyses; each ascus or theca contains 

 four spores. Several other species are com- 

 mon in Britain. 



BIBL. Berk. Hook. Br. Fl. ii. pt. 2, 211 ; 

 Ann. N. H. vi. 359, 2 ser. vii. 185; Tulasne, 

 Ann. So. Nat. 3 ser. xx. 133, pi. 16. 



CENOMY'CE. See CLADONIA. 



CENTROP'AGES, Kroyer. A genus of 

 Copepodous Entomostraca. 



C. typicus j brown ; North Sea. 



C. hamatus ; marine. 



BIBL. Brady, Copepoda (Ray Soc.}, i. 

 p. 64. 



CEPHALOP'ODA. An order of Mol- 

 lusca, containing the Nautilus, the Argonaut, 

 the Octopus, _ the Cuttle-fish (Sepia), &c., 

 with the fossil Belemnites and Ammonites. 

 The cartilage of the cuttle-fish is noticed 

 under CARTILAGE ; the dorsal plate or se- 

 piostaire under SHELL. 



The chromatophores, or cutaneous pig- 



