532 



MOVEMENTS. 



differences. In the loose areolar tissue beneath the skin and between the muscles, and 

 in the loose structure surrounding some of the glands and connecting 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 semi- 

 transparent, 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 

 they present a striking contrast to the inelastic fibres in their form and size. Although 

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



FIG. 157. Loose net-work of connective tissue from the human subject, showing the fibres and cells. (Eollett.) 



a, a, a capillary blood-vessel 



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 nucleoli. On the addition of acetic acid the cells disappear, but the nuclei are 

 unaffected. These are the fibro-plastic elements of Lebert, and the embryo-plastic ele- 

 ments of Robin. It is impossible to give any accurate measurements of the cells, on 

 account of their great variations in size. The length of the nuclei is from ^Vo to ^Vs 

 of an inch, and their diameter, from -^^ to ^-5- of an inch. The appearance of the 

 connective tissue, with a few cells and nuclei, is represented in Fig. 157. 



Between the muscles, and in the substance of the muscles between the bundles of 

 fibres, there always exists a greater or less quantity of adipose tissue in the meshes of 

 the fibrous structure. 



Blood-vessels and Lymphatics. The muscles are abundantly supplied with blood-ves- 

 sels, generally by a number of small arteries with two satellite veins. The capillary 



