CONNECTIVE TISSUE. Ixix 



It has been a question whether, when the fat undergoes absorption, the vesicles are 

 themselves consumed along with their contents. Dr. W. Hunter believed that they 

 still remained after being emptied ; he was led to this opinion by observing the con- 

 dition of the areolar tissue in dropsical bodies from which the fat had disappeared, 

 there being in such cases a marked difference in aspect between the parts of that 

 tissue which had originally contained fat and those which had not, which difference 

 he attributed to the persistence of the empty fat-vesicles. Gurlt states that the fat- 

 cells in emaciated animals are filled with serum, and this statement is fully confirmed 

 by the observations of Kb'lliker, Todd and Bowman, myself, and others. 



CONNECTIVE TISSUE. 



This substance consists of fibres of two kinds, more or less amorphous 

 matter, and peculiar corpuscles. By means of its fibres it serves in the 

 animal body as a bond of connection of different parts ; also as a covering 

 or investment to different organs, not only protecting them outwardly, but, 

 in many cases entering into their structure and connecting and supporting 

 their component parts. The corpuscles, on the other hand, are destined for 

 other than mechanical purposes ; they appear to be essentially concerned in 

 the nutrition and reparation of tissues. 



Three principal modifications or varieties of connective tissue have long 

 been recognised, consisting of the same structural elements but in widely 

 different proportions, and thereby exhibiting a difference in their grosser or 

 more obvious characters and physical properties. They are known as the 

 areolar, the./i&rous, and the elastic tissues, and will be now severally treated 

 of. Without disregarding the alliance of cartilage and bone to the connec- 

 tive tissues, we shall not, in imitation of some respected authorities, include 

 them in the same group ; but there remain certain forms of tissue, occurring 

 locally, or met with as constituents of other textures, which properly belong 

 to this head, and will be briefly considered in a separate section as sub- 

 ordinate varieties of connective tissue. 



Cartilage and bone are included in the group of connective tissues or connective 

 substances by several eminent German histologists, and present undoubted points 

 of relationship with these tissues, both in their nature and the general purpose 

 which they serve in the animal frame. Thus, yellow cartilage shows an unmistakable 

 transition to elastic connective tissue, as fibro-cartilage does, even more decidedly, to 

 white fibrous tissue. Moreover, the animal basis of bone agrees entirely in chemical 

 composition, and^ in many points of structure, with the last-named tissue. Still, 

 when it is considered that cartilage, in its typical form, consists of a quite different 

 chemical substance, chondrin, and that bone is characterised by an impregnation of 

 earthy salts, it seems more consistent with the purpose of histological description to 

 recognise cartilage and bone as independent tissues. As to their community of 

 origin, little stress need be laid on it as a basis of classification, seeing that the origin 

 of blood-vessels, nerves, and muscles, may be traced up to protoplasm-cells, to all 

 appearance similar to those that give rise to the connective tissues, and belonging to 

 the same embryonic layer. 



THE AREOLAR TISSUE. 



If we make a cut through the skin and proceed to raise it from the sub- 

 jacent parts, we observe that it is loosely connected to them by a soft 

 filamentous substance, of considerable tenacity and elasticity, and having, 

 when free from fat, a white fleecy aspect ; this is the substance known by 

 the names of "cellular," "areolar," "filamentous," "connective," and 



