CHALK. 



[ 160 ] 



CHAM^ESIPHON. 



striata, and subangnlata, Vagimdina Icevigata 

 and longa, Verneuilina spinulosa, and Vul- 

 vulina pennatida. D'Orbigny enumerated 

 22 species from the English chalk, including 

 some of the above ; many others have also 

 been found. 



The genera and subgenera in which they 

 are grouped are Bolivina, BUUMINA, CAL- 

 CARINA, Cristellaria, Dentalina, Flabellina, 

 Frondicularia, Gaudnjina, GLOBIGERINA, 

 Haplophragmium,Heterostomella,Lingulina, 

 LAGENA, LITUOLA, Margimdina, MILIOLA, 

 Nodosaria, NODOSARINA, Planularia, Pla- 

 nulina, PLANORBULINA, POLYMORPHINA, 

 PULVINULINA, Quinquelocidina, Ramnlina, 

 ROTALIA, Sagrina, SPH^EROIDINA, TEX- 

 TULARIA, TINOPORUS, Tritaxitt, TROCHAM- 

 MINA, Truncatulina, VALVULINA, Verncui- 

 lina, Virgulina, and Webbina. 



Ehrenberg found two Diatomaceae in the 

 English chalk, viz. Fragilaria capucina (F. 

 rhabdosoma), and Fr. pinnata, Ehr. (=F. 

 mutabilis, Sm.). Some other Diatomacese 

 referred by Ehrenberg to the chalk, belong 

 to foreign chalk and to totally different beds. 



The material of chalk comprises very 

 minute, numerous, and remarkable bodies, 

 called crvstalloids and morph elites byEhren- 

 berg (PI. 25. fig. 15). They are elliptical 

 or rounded, and flattened, from 1-10,000 to 

 1-2500" in length, the most numerous per- 

 haps 1-3000"; some of them consist of a 

 simple ring (a) ; in others this is marked 

 with pretty regular transverse lines, so as to 

 make it appear jointed (b) ; in others, again, 

 there is a thinner central portion, often ex- 

 hibiting one or more granules (c). Ehren- 

 berg regarded these as arising from the dis- 

 integration of the microscopic organisms 

 forming the chalk into much more minute 

 calcareous particles, and their reunion into 

 regular elliptical j>lates or disks by a pecu- 

 liar process, differing essentially from, and 

 coarser than that of crystallization, but 

 comparable with it, one probably preceding 

 all slow crystalline formation, and causing, 

 but not alone, the granular state of solid 

 inorganic matter. These microscopic bodies 

 have of late years been regarded as the 

 agglomerated or separate plates of very 

 simple protozoan organisms by Huxley, 

 Wallich, and Sorby. By Carter they are 

 believed to belong to an Alga (Cocco- 

 LITHS). 



The best method of examining chalk for 

 minute Foraminifera is this : place a drop 

 of water upon a glass slide, and put into it 

 as much finely scraped chalk as will cover 



the point of a pen-knife; then diffuse it 

 through the water, and set it aside for a few 

 seconds. Next remove the finest particles 

 which are suspended in the water, together 

 with most of the water, and allow the re- 

 mainder to become perfectly dry. Moisten 

 this remainder with oil of turpentine, nnd 

 warm it over a spirit-lamp ; then add Ca- 

 nada balsam, and digest it upon the brass 

 table (!NTR. xxviii). but without its froth- 

 ing. ' A preparation thus made seldom fails ; 

 and when magnified 300 diameters, the mass 

 is seen to be chiefly composed of minute 

 well-preserved organisms. As thus pre- 

 pared, the cells of the Foraminifera first 

 appear black, with a white central spot 

 (PL 24. fig. 3), which is caused by air- 

 bubbles contained within the cells/ The 

 balsam gradually penetrates into the cells, 

 the black rings of the air-bubbles disappear, 

 and the minute, frequently very circuit 

 cells of the Foraminifera become visible. 

 See FLINT, and FORAMINIFERA. 



The crystalloids are best examined in 

 common whiting, or powdered chalk, which 

 has been shaken with water and set aside. 

 A very minute quantity removed with a 

 dipping tube will exhibit them. 



BIBL. The various works on geology, as 

 those of Lyell and Ansted ; Mantell, Won- 

 ders, Medals of Creation, and Ann. N. H. 

 1845, xvi. p. 73 ; Bowerbank, Geol. Tr. 2s. 

 vi. ; Ehrenberg, Abh. d. Berlin. Ak. 1838 

 (Ann. N. H. 1841, vii.), and Abh. d. Scrl 

 Ak. 1840 (Taylor's Sc. Mem. iii.), and Mi- 

 krogeologie, 1854 ; Parker and Jones's Ehr. 

 resume, Ann. N. H. 1872; Williamson, 

 Manchester Lit. Phil. Soc. viii. 1847 ; Mor- 

 ris, Cat. Br. Fossils, 1854 j D'Orbigny, 

 Mem. Soc. Geol. d. France, iv. (Abs., Ann. 

 N. H. 1841, vii. p. 390) ; Zirkel, Mineral i<>n 

 #c.,1873, 303 j Dixon's Sussex, 2 ed., 1878, 

 123 & 283. 



CHALK-STONES. This term is vul- 

 garly applied to the white concretions 

 formed around the joints in chronic gout, 

 or, as it is sometimes called, rheumatic gout. 

 They consist of very minute needles of urate 

 of soda (PI. 12. fig-. 12 b). 



CHAIkLENE'MA, Kiitz. A supposed 

 genus of Leptotricheous Algae, consisting of 

 dusky-coloured jointed filaments, forming 

 flocks in various syrups. Doubtless the my- 

 celia of some Fungi, such as PENICILLIUM. 



BIBL. Kutzing, Sp. Alg. 158. 



CHAM^E'SIPHON, Braun. A genus of 

 Oscillatoriaceee (Confervoid Algae). 



Char. Trichomata erect, seruginous or 



