CHAP, in.] AREOLAR TISSUE. 77 



and preserves them from undue separation during contraction ; but 

 even here it is bound within the same limits as the capillaries, not 

 penetrating the sarcolemma to touch the contractile element within. 

 It enters the muscles abundantly along with their vessels and nerves. 

 It is remarkable, however, that the central organ of the circulation, 

 like the central organ of the nervous system, contains this tissue in 

 very small proportion ; one reason of which seems to be, that its 

 fibres differ from the parallel fibres of other muscles, by twining 

 among one another, and thus are enabled to dispense with an ex- 

 traneous bond of connexion. 



Besides penetrating between the fibres of the muscles, whose 

 minute parts are in continual movement upon one another during 

 contraction, it generally invests their exterior, in a profusion pro- 

 portioned to the extent to which these organs move as a whole 

 upon neighbouring parts, of which the best examples may be seen, 

 between the great muscles of the extremities ; between these and 

 their enveloping fasciae (not their fasciae of origin); under the 

 occipito-frontalis muscle and its tendon ; and in the upper eye- 

 lids. 



The areolar tissue is also present in immense quantities under the 

 skin of most parts of the body, and especially where great mobility 

 of the integument is required, either as a protection to deeper 

 organs against external violence, or to facilitate the various move- 

 ments of the frame. Such are the regions of the abdomen, and 

 of several of the articulations, and the eyelids. 



Around internal organs which change their form, size, or position 

 in the routine of their functions, and which are wholly or partially 

 without a free surface, as the pharynx, oesophagus, lumbar colon, 

 bladder, &c., this tissue is abundant, and its filaments so long, 

 tortuous, and laxly interwoven, as to admit of a ready and extensive 

 motion on the neighbouring viscera. 



This tissue likewise forms a layer lying under the mucous and 

 the serous membranes in almost every situation, though presenting 

 great variations of quantity and denseness : it renders the move- 

 ments of such parts easy. It also closely invests the exterior of 

 every gland and parenchymatous organ, and enters more or less 

 abundantly into its inner recesses, along with its vessels, nerves, 

 and absorbents : but there is no doubt that it has been supposed to 

 have a much greater share in the formation of this numerous class 

 of organs than an ultimate anatomical analysis of them, conducted 

 with careful precision, will at all warrant. In all these cases it is a 

 more or less copious attendant on the vessels ; but wherever, either 



