PRIMARY TISSUES : AREOLAR TISSUE. 39 



as in dropsy, it descends by gravity to the lowest situation. 

 Hence, the legs swell more frequently than any other parts. 

 In its natural state, this tissue possesses considerable elas- 

 ticity ; hence, when we press upon any soft part, and force out 

 the fluid beneath into the tissue around, the original state 

 returns as soon as the pressure is removed. But in dropsy, 

 it appears as if the elasticity of the fibres were impaired or 

 destroyed by their being over-stretched ; for when we press 

 with the finger upon a dropsical part, a pit remains for some 

 time after the finger has been removed. 



25. This Areolar tissue is diffused through almost the 

 whole fabric of the adult animal, and enters into the compo- 

 sition of almost every organ. It binds together the minute 

 parts of which the muscles are composed ; it lies amongst the 

 muscles themselves, connecting them together, but yet per- 

 mitting them sufficient freedom of motion ; it exists in large 

 amount between the muscles and the skin j it forms sheaths 

 to the blood-vessels and nerves, and so connects them with 

 the muscles that they shall not be strained or suddenly bent 

 by the movements of the latter ; and it enters into the struc- 

 ture of almost every one of the organs which are contained 

 in the cavity of the trunk, uniting its parts to each other, and 

 keeping the whole in its place. But it is a great mistake to 

 assert, as it was formerly common to do, that it penetrates the 

 harder organs, such as bone, teeth, and cartilage. Its purpose 

 obviously is to allow a certain amount of motion among the 

 parts it unites ; and we find that the more free this motion is 

 required to be, the larger is the proportion borne by the 

 yellow or elastic fibres, to the white or non-elastic. 



26. Although the Areolar tissue contains a very large 

 number of blood-vessels and nerves, yet it does so merely 

 because it furnishes the bed or channel in which they are 

 conducted to the parts where they are really wanted. Its 

 own vitality is low, and its sensibility very slight. It is 

 quickly reproduced after injury ; and it is by its means that 

 losses of substance are repaired in tissues of a more elaborate 

 kind, which are not so easily regenerated. 



27. The continuity or connectedness of this tissue over the 

 whole surface of the body, admits air to pass readily from 

 one part to another ; and the inflation or blowing-up of its 

 cavities with air, which has sometimes happened accidentally, 



