CONNECTIVE TISSUES AREOLAR TISSUE. 



63 



the granules are essentially dependent upon disturbances or variations of 

 the circulation. Saviotti ' has observed the migration of the pigment cells 

 of the wall of the frog's foot into the bloodvessels after irritation, and the 

 time occupied in the transit of the cells through the walls of the blood- 

 vessels, was about twelve hours. M. Tschaussow 2 observed, on the contrary, 

 the passage of a pigment cell out of a vein and its division into two in the 

 tissues. 3 When the cell is crushed, the black particles escape and exhibit 

 peculiar vibratory or quivering movements. The coloring matter or melanin 

 is insoluble in water and most reagents, but it dissolves in weak alkalies. It 

 is not bleached by chlorine. It contains iron and nitrogen. 



44. A REOLAR, FIBROUS, AND ELASTIC TISSUES/ Ordinary connective tissue 

 in its fully developed form, may be shortly defined to consist of plasmatic cor- 

 puscles scattered through a fibri liar matrix. The corpuscles, though _ pre- 

 senting a general resemblance to a cell, possess no cell-wall, are very variable 

 in form, and have occasionally been observed to undergo spontaneous changes 

 of form (Kiihue). They may be regarded as small masses of " germinal 

 matter," preserving their original activity, whilst the matrix consists of 

 " formed material," proceeding from the modified cell-walls and intercellular 

 substance. In many cases a third morphological element, the elastic, enters 

 into the composition of this tissue, conferring properties upon it which are 

 of great importance in the discharge of the functions that in some situations 

 it has to perform. Amongst the principal ex- 

 amples of ordinary connective tissue met with 

 in the body we may include with Bouchard 

 the various structures termed tendons, liga- 

 ments, fascia?, apoueuroses, periosteum, and 

 perichondrium ; the investing membranes of 

 many organs, as the dura mater, pericardium, 

 tunica albugiuea of the testis and of the ovary, 

 and the sclerotic and corueal coats of the eye. 

 It also forms the basis of the- true skin, of 

 mucous, serous, and synovial membranes, the 

 chorion, vascular sheaths, and tunics, and 

 amorphous membranes, as the hyaloid humor 

 of the eye, and the envelopes of glandular 

 follicles. These all present a general simi- 

 larity of structure and chemical composition, 

 though differing in minor details. The most 

 form, or that met with in fibrous 



FIG. 22. 



White or Non-elastic Fibrous Tissue. 



common orm, or 



membranes, appears when examined with the microscope to be composed of 

 bundles of wavy filaments (Fig. 22), which either run parallel to one an- 

 other with but few cross fibres as in tendons, or decussate with one another 

 in every direction as in the sclerotic, leaving irregular interspaces, lacuna? 

 or areolse, the imperfectly bounded walls of which permit the passage of 

 fluids in every direction. The individual fibres do not exceed Yfio^oth of an 

 inch in diameter. The addition of a little acetic acid, by its different action 

 on the three elements that commonly enter into the composition of the tissue, 

 enables them to be easily distinguished. The white wavy filaments swell 



1 Centralblatt, 1870, pp. 145 and 161. 



2 Ib., p. 309. 



3 The movements of the pigment in the skin of the Chameleon have been well 

 described by Briicke in his Vorlesungen tiber die Physiologic, 1874, p. 440. 



4 For good papers on Connective Tissue see S. Marty n, in Dr. Beale's Archives of 

 Medicine, vol. ii, p. 99; and Dr. Beale in idem, vol. iii. 



