VOLUNTARY MUSCLES. 4:55 



fibres are collected into bundles of very variable size, and are 

 held together by an adhesive amorphous substance. The 

 wavy lines that mark the bundles of fibres give them a very 

 characteristic appearance. 



The direction and arrangement of the fibres in the vari- 

 ous tissues present marked differences. In the loose areolar 

 tissue beneath the skin and between the muscles, and, in the 

 loose structure surrounding some of the glands and connect- 

 ing the sheaths of blood-vessels and nerves to the adjacent 

 parts, the bundles of fibres form a large net-work, and are 

 very wavy in their course. In the strong, dense membranes, 

 as the aponeuroses, the proper coats of many glands, the 

 periosteum and perichondrium, and the serous membranes, 

 the waves of the fibres are shorter, and the fibres themselves 

 interlace much more closely. In the ligaments and tendons, 

 the fibres are more nearly straight, and are all arranged 

 longitudinally. 



On the addition of acetic acid, the bundles of inelastic 

 fibres swell up, become semitransparent, and the nuclei and 

 elastic fibres are brought out. The proportion of elastic 

 fibres differs very much in different situations, but they are 

 all of the smallest variety, and present a striking contrast to 

 the inelastic fibres in their form, and size. Though they 

 are still very small, they always present a double contour. 



Certain cellular and nuclear elements are always found 

 in the connective tissue. The cells have been described 

 under the name of connective-tissue cells. They are very 

 irregular in size and form, some of them being spindle-shaped 

 or caudate, and others star-shaped. They possess one, and 

 sometimes two or three clear, ovoid nuclei, with distinct nu- 

 cleoli. On the addition of acetic acid the cells disappear, 

 but the nuclei are unaffected. These are the fibro-plastic ele- 

 ments of Lebert, 1 and the embryo-plastic elements of Eobin. 2 



1 LEBERT, Physiologic pathologique, Paris, 1845, tome ii., page 120. 

 8 LITTBE ET ROBIN*, Didionnaire de medecine, Paris, 1865, Article, Embryo- 

 plastique. 



