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; 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 ahnost 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,. 
