CELL-CONTENTS. 



[ 124 ] 



CELLULAR TISSUE. 



produced out of the cellulose by the chemical 

 action. (See Cellulose and Chemical 

 Reagents.) Cell-membranes and their 

 modifications are examined of com'se in si- 

 milar preparations to those mentioned as dis- 

 playing the forms, &c. of cells. 



BiBL. — General. Text-hook of Structural 

 Botany; Mold, Vegetable Cell, transl. by 

 Henfrey, 1853; Schacht, Die Pflanzenzelle, 

 Berlin, 1852; Meyen, PflanzenpJiysiologie, 

 Phytotomie ; Morren, Bulletin de VAcad. de 

 Bruxelles, v. No. 3. — Development. Two 

 works indispensable for the study of the 

 present state of this question, contain cita- 

 tions of most of the important authorities, 

 viz. Mohl, Vegetable Cell, and A. Braun, 

 Rejuvenescence, Sfc, Ray Society's Publica- 

 tions, 1853.— Cell-Membrane. Mohl, On 

 Cellidose, Bot. Zeitung, v., transl. in Scien- 

 tific Memoirs, 2nd ser. {Nat. Hist.), vol. i. 

 90; Ueber die Zusammensetzung der Zell- 

 membran, Bot. Zeit. xi. 753 ; Harting, Mul- 

 der's Physiol. Chemistry, transl. by From- 

 berg, Edinburgh, 1849; Botan. Zeitung, v. 

 337; Kiitzing, Grundz. der Phil. Botanik, 

 pt. 1. 1852; J. G. Agardh, De Cellula vege- 

 tabili, &c., Lund. 1852; Caspary, Ueber 

 Streifung der Zellenwand, Bot. Zeit. xi. 801; 

 Criiger, Die primitif. Faser, Bot. Zeit. x\\. 57. 



CELL-CONTENTS.— This term (in Ger- 

 man Inha.lt) corresponds, in regard to vege- 

 tables, to the word endochrome as used by 

 Mr. Thwaites, Mr, Ralfs, and some of the 

 French botanists. It refers here most essen- 

 tially to the primordial utricle, as this is the 

 part effective in development, while the sub- 

 stances imbedded in or lying in the cavity of 

 this are variable according to age, stage of de- 

 velopment, &c. See Primordial utricle. 



CELLULAR TISSUE, of Animals, 

 sometimes called fibro-cellular, connective, or 

 areolar tissue. We shall use the term areo- 

 lar tissue (although fibro-areolar would be 

 the most appropriate) ; but as an account of 

 it would perhaps be looked for under the old 

 name, we have placed it under that head. 



Areolar tissue is very generally diffused 

 throughout the bodies of vertebrate animals, 

 filling up the interspaces between the various 

 organs, and entering into the composition 

 of most of them. 



It consists essentially of white fibrous tis- 

 sue, mostly containing the elements of the 

 yellow or elastic tissue. The most common 

 form of the white fibrous element is that of 

 minute, delicate, transparent fibres, called 

 fibrillar, with pale outlines (PI. 40. fig. 41) ; 

 these are sometimes single, at others united 



into bundles or fasciculi. The fibres as well 

 as the bundles sometimes pursue a straight 

 course, at others they are elegantly curved 

 and wavy, interlacing in all directions, and 

 leaving larger or smaller areola? or spaces 

 between them, the larger of which are visible 

 to the naked eye. The fibrillse are about 

 1-40,000 tol-20;000", and the fasciculi about 

 1-7000 to 1-3000" in diameter. In the fas- 

 ciculi, they are connected by an amorphous, 

 transparent, gelatinous substance. When 

 treated with acetic acid, the fibres swell, be- 

 come paler, and lose their distinctness, the 

 bundles appearing as if fused into a gelati- 

 nous mass (fig. 31. p. 59), and round or 

 elliptical nuclei, with their long axes parallel 

 to the direction of the fibres, are brought 

 to view (PI. 40. fig. 42). 



The yellow fibrous tissue occurs in the 

 form of fine fibres, with dark outlines ; these 

 sometimes run straight, at others they are 

 wavy, at others coiled or forming rings 

 around the bundles of the areolar tissue, or 

 running parallel with and between them. 

 They are best seen when the tissue has been 

 rendered transparent by the addition of ace- 

 tic acid. 



These fibres cannot always be detected in 

 areolar tissue; sometimes it forms an almost 

 homogeneous, finely granular, or slightly 

 striated mass. 



Areolar tissue consists chemically of gela- 

 tine, which may be obtained from it in solu- 

 tion by boiling. 



The various complex structures into the 

 composition of which the white fibrous ele- 

 ment enters, as the mucous membranes, skin, 

 fatty tissue, &c., are noticed under the re- 

 spective heads. 



Areolar tissue is met with in all classes of 

 vertebrate animals, and, as found in them, it 

 agrees essentially with that of man. It oc- 

 curs more rarely in the Invertebrata, and 

 when present, is rather homogeneous, rarely 

 fibrous, as in the Cephalopoda, the mantle 

 of the Mollusca, &c. 



Areolar tissue is developed from the em- 

 bryonic corpuscles or cells (?). These be- 

 come elongated and fusiform; sometimes 

 the ends are branched. They unite with 

 each other, and the ends become longitudi- 

 nally split into the component fibrilla? of the 

 future tissue. The substance of the cor- 

 puscle subsequently splits in the same man- 

 ner. But whether the corpuscle is a solid 

 body or protoplast, or whether it is a true 

 cell, and secondary deposition takes place 

 within it, the deposited substance subse- 



