44 



ANATOMY. 



one plane by areolar tissue constitute the fibrous membranes, such as 

 the periosteum, the pericardium, the outer coat of the eyeball, the 

 broader ligaments and tendons, and the strongest parts of the fascia 



Fig. 17. 



Fig. 17. a, interlacing bundles of colorless wavy filaments of the areolar connective tissue, fc, parallel 

 wavy filaments of the fibrous connective tissue, c, a single filament, swollen up after the addition of weak 

 acetic acid, and showing certain fine dark fibres of elastic tissue coursing upon it. Magnified 400 diameters, 

 (a, 6, The Author ; c, Kolliker.) 



investing the muscles of the limbs. Straight parallel bands closely 

 held together, constitute flattened or rounded fibrous cords, such as 

 certain ligaments, and the long tendons of many muscles. 



The areolar and fibrous tissues are not very vascular ; nor have 

 they many nerves. They are almost insensible, except when inflamed. 

 Tendons and ligaments suffer, however, from being overstretched. 



Elastic tissue. This tissue is so named because it is not merely 

 extensible, but retracts after it has been stretched, like vulcanized 

 India-rubber. 



The very fine elastic fibres, which, as already mentioned, are mixed 

 with the filaments of the areolar and fibrous tissues, are best shown 

 by treating these latter with acetic acid, which causes the white fila- 

 ments to swell up to a great size, whilst the elastic fibres remain singu- 

 larly well defined, appearing as dark lines lying upon and even sur- 



Fig. 18. 



Fig. 19. 



Fig. 18. Dark, clear, branching, interlaced and curly fibres of the elastic tissue. Magnified 200 diameters. 

 (The Author.) 



Fig. 19. a, a layer of elastic tissue, in which the component fibres are flattened and joined together so 

 frequently as to form a very close network. From the pulmonary artery of a horse, b, a still closer net- 

 work of the same kind, forming a perforated or fenestrated elastic membrane. From the carotid artery of 

 the horse. Magnified 180 diameters. (Kolliker.) 



rounding the white filament, Fig. 17, c. When present as the chief 

 constituent of any part, the elastic tissue has a yellowish color ; hence 



