64 CONNECTIVE TISSUES AREOLAR TISSUE. 



up and become transparent, losing in great measure their fibrillar character. 

 The corpuscles appear as dark granular bodies, and the elastic tissue when 

 present appears in the form of fine dark fibres with well-defined borders, 

 which pursue a tortuous course, and often branch and anastomose. Such 

 tissue presents few or no bloodvessels and nerves, those seen in any section 

 being in all probability on their way to other parts. In many localities, as 

 beneath the skin, the areolre of the connective tissue are filled with lobules 

 of fat. Tendons and ligaments may be regarded as modifications of connec- 

 tive tissue, and a considerable amount of discussion has lately arisen in re- 

 gard to their structure. 1 Boll and Mitchell Bruce, who are supported by 

 all the more recent inquirers, consider the cell-elements of tendinous tissue 

 to be quadrilateral plates, which bend round the fasciculi of fibrils, two 

 forming an investment for each fasciculus at any given height. The cell- 

 elements as a whole (Ciaccio), or a certain portion of each only (elastic stria 

 of Boll), stain deeply with Carmine. Ciaccio maintains in addition, that 

 besides the cells each fasciculus of fibres is inclosed in a delicate sheath 

 containing fine elastic fibres. The opposed surfaces are moistened with a 

 thin fluid which closely resembles the serum of blood in its composition. In 

 the case of the serous and synovia! membranes, which as Klein has shown 

 are dilatations of the lymphatic system, the connective tissue is so arranged 

 as to constitute bags or sacs, the inner surface of which is, for the most part, 

 lined by a single layer of flattened epithelial cells, forming an exquisitely 

 smooth and polished surface, that materially facilitates the constant gliding 

 movements to which these parts are subjected. Besides these, more rounded 

 cells, termed germinating endothelial cells by Klein, are found in certain 

 regions, as will be more fully explained in the section on the lymphatic 

 system. In the vitreous humor of the eye, and in the substance which con- 

 stitutes the greater part of the umbilical cord, there exists a peculiar form 

 of connective tissue, termed mucous or gelatinous tissue. The structure of 

 the vitreous is difficult to determine, but it appears to be composed of a 

 jelly-like fluid, contained in the meshes of a network of exquisitely fine fila- 

 ments ; it is doubtful whether any cells are present. In the cord, the matrix 

 is soft, transparent, and homogeneous as in the vitreous, but presents round, 

 fusiform, or stellate cells, with branched and communicating prolongations 

 scattered through it. This kind of connective tissue is found only in em- 

 bryonic structures, or in organs retaining their embryonal characters. In 

 mucous membranes the layer of connective tissue is much thicker and more 

 vascular than in serous, frequently contains minute glands, and instead of 

 a single layer, is covered by many layers of epithelial cells, of a more or 

 less rounded or columnar form. In all instances mucous membranes con- 



1 The following being some of the more important papers that have been pub- 

 lished upon them : 



Ranvier, Brown-Seipiard's Archives de Physiologic, t. ii, p. 471. 



Rollett, Strieker's Manual of Histology, Syd. Soc. Trans., 1870, p. 47. 



Guterbock, Centralblatt, 1870, p 33. 



Boll, Schultze's Archiv f. Microseop. Anat , Band vii, pp. 28 and 275, 1871. 



Krause, Deutsche Klinik, 1871 



Lan/.ilotti Buoni*anti, Pamphlet. Milan, 1871. 



.Mitchell Bruce, Quart. Journ. of Mic Sci., vol. xii, p. 129. 1872. 



''iaccio, Memoric del Acndemia <li Bologna, ser. iii, t. ii. 1872. 



A.dk'kes, < VntralMatt, 1872, p. 597. 



(Jcrhirh, Sitxnngsher. d. Phys. Med. Sooioti'it zu Erlangen, July, 1872. 



V. Torolc, Centralblatt, 1872, pp. 06 and 675. 



Klein and Sanderson, Centralblatt, 1872, p. 33, and Handbook, 1873. 



Ditlevson. CentralMatt, 1873, p. 670 (Abstract). 



Dr. G. Thin, Edin. Med. Journ., Sept. 1874. 



