94 GENERAL ANATOMY OF THE TISSUES. 



glands), certain of the so-called memhrance. "prop'icB of the glands ap- 

 pear to come under this head also ; yet, since some of them do not 

 belong here, and consist of a very different substance from connective 

 tissue, as, for example, that of the kidneys, and since we have no thorough 

 investigation of these structures, for the present nothing decided can be 

 said upon the subject. 



h. Loose or areolated connective tissue^ (" amorphous connective tissue" 

 of Henle), consists of a soft meshwork of reticulated, or variously inter- 

 woven bundles of connective tissue, which in larger or smaller quantity 

 constitute a filling up and uniting mass between the organs and their 

 parts, and appear under two forms : — 



1. As adipose tissue, when numerous fat-cells are contained in the 

 meshes of an areolated tissue which is usually very poor in elastic fibres. 



2. As common lax connective tissue, when the latter are few or want- 

 ing. The adipose tissue occurs principally in the skin forming the 

 panniculus adiposus ; in the larger cylindrical bones, as yellow bone- 

 medulla ; in the orbit ; around the kidneys ; in the mesentery and the 

 omentum ; around the spinal marrow ; in the nerves and vessels, and 

 in muscles. The areolated connective tissue is widely distributed be- 

 tween the separate organs and the viscera of the neck, thorax, abdomen, 

 and pelvis, and everywhere along the course of the vessels and nerves, 

 and in the interior of the muscles, nerves, and glands. 



The connective tissue is found in all the four classes of the vertebrata 

 in about the same condition as in man ; while, on the other hand, in the 

 invertebrata it is very rare, and when present is more homogeneous, 

 or consists of isolated cells and intermediate substance, rarely more 

 fibrous, as in Cephalopoda, in the mantle of bivalves, in the peduncle 

 of the LinguliTS, and of the Cirripeds. Fat-cells also do not occur 

 among the lower animals to the same extent as among the higher. The 

 firm connective tissue is here replaced by a chitinous substance, or by 

 one consisting of cellulose, and by calcareous or horny tissues. 



Opinions are still divided as to the structure and development of the 

 connective tissue. Whilst the majority ascribe a distinctly fibrous struc- 

 ture to it, and suppose it to consist of bundles, and these again of fibrils, 

 Reichert considers this tissue to be more homogeneous, and regards the 

 fibrillation partly as artificial, partly as the expression of a folding, a 

 view to which Bidder and Virchow are also inclined. For my own 

 part, I find a certain amount of truth in Reichert's conception, inso- 

 much as it is not to be denied that there also exists a non-fibrillated, 

 more homogeneous connective tissue, which had previously been little 

 investigated ; but I am nevertheless of opinion, that, as applied to the 



* [Tliis second variety, " loose or areolated connective tissue," is generally described as 

 areolar tissue, or under the faulty name of cellular tissue. — DaC] 



