484 
degree by the addition of concentrated saline 
solutions, whereas, by some experiments lately 
made with my friend Mr. Lane, I have been 
satisfied that the mucus globules are so affected, 
and may easily be observed, under a powerful 
microscope, to expand or contract according 
as water, or strong solutions are mixed with 
them. ‘The mucus globule admits, in fact, of 
the exudation or imbibition of fluids according 
to the laws of endosmose and exosmose, and 
were the greater part of a mass of mucus 
composed of these globules, we should observe 
it to corragate in concentrated solutions; but 
such is not the case, as I have before stated, 
with many of the most viscous forms of mucus, 
while the mucus of the bladder, on the con- 
trary, which (except in severe diseases) is one 
of the least coherent forms, shows a tendency 
to contract under such circumstances, and on 
microscopic examination proves to contain 
globules in large number in proportion to its 
mass. This reaction, I think, renders it very 
probable that the view I have mentioned is the 
correct one. Most forms of mucus swell when 
moistened by water or weak solutions; but 
this is no proof of action on organic globules 
unless the opposite experiment (contraction by 
strong solutions) can be successfully performed. 
The mucus globule varies greatly, as seen in 
different secretions; so much so that any one 
who has examined this subject microscopically 
must be familiar with a form of globule peculiar 
to each secretion. I shall first describe the 
globule generally, and then proceed to notice 
its varieties in appearance. The mucus globule 
is nearly transparent, and larger than the blood 
globule. As it exists in the saliva and urine 
it is of a very regularly circular form, with 
a well defined margin and a somewhat granular 
surface. In the more adhesive forms of ex- 
pectoration, however, it loses this well defined 
and rounded form, and its translucence is 
impaired ; the granular surface can always, 
however, be seen. In a portion of mucus 
taken from the back of the throat I lately 
had an opportunity of examining this last 
mentioned condition, and took occasion to 
examine whether or not it depended on a 
partially empty condition of the globule, 
which could be remedied by the addition of 
water. I found, by careful treatment, in this 
way under the microscope, that the bodies 
gradually assumed a more rounded form, 
and eventually exhibited an appearance almost 
identical with the more transparent globules 
observed in the saliva and urine. By sub- 
sequently adding a concentrated solution of 
sugar to them, however, the original appearance 
was speedily reinduced, owing to the endos- 
modic action of the sirop. is experiment 
has led me to a belief that the cause of 
difference in the microscopic appearance of the 
mucus globule, as seen in different secretions, 
is attributable rather to the circumstances 
under which it is placed than to any difference 
in organization. 
It would appear, from the facts collected 
up to the present moment on this subject, that 
we are justified in considering, 1st, that mucus 
MUCOUS MEMBRANE. 
is a compound of albumen in a state of close 
combination with alkaline salts, and probably 
free alkali; 2nd, that the artificial compound 
formed by the addition of alkalies and neutral 
salts to albuminous matter is essentially the 
same as mucus; 3rd, that the mucus ¢ 
is superadded to the viscous matter in 
secretions of mucous membranes, and is in 
no way concerned in imparting the peculia 
tenacious character to such fluids. y 
A great deal of trouble has been taken | 
devise chemical means of distinguishing be- 
tween pus and mucus, or to detect the presene 
of the former when existing combined i 
small proportion with the latter. No chemics 
method of inquiry can ever be applicable to 
this question: the microscope must be ha 
recourse to for the detection of the pus globule, 
if the mucus be suspected to contain it in 
quantity so small as to escape casual exami- 
nation. When pus is present, however, even 
in very small proportion to the mucus, if 
physical characters are so distinct that 
chemical or mic ical tests can possib 
be required. Considered as a means of prov 
Pe 
oDUuLe | 
a 
the folly of using chemical tests is at once 
apparent when we recollect that the questic 
as regards pus is entirely one of structur 
and we cannot in reason use chemical te 
to determine the presence or absence of 
globule. When pus exists as a deposit i 
urine, we may easily distinguish it he 
hosphates with which it is sometimes cor 
‘ounded by adding an alkali, as recommende 
by Dr. Babington, in whieh case the depos 
(which must be previously separated by | 
cantation from the urine) assumes the glair 
character of mucus, and thus shows its alb 
minous nature. As affording us a distinetij 
test, therefore, between these two substance: 
chemistry becomes useful; but inasmuch ; 
the addition of alkali to most forms of albi 
- 
minous matter developes a mucous ‘i 
the re-agent cannot correctly be called a t 
for pus. We become assured of the presi 
of pus by this reaction only, because previt 
experiment has shown that the 
and pus are the only two substances assu) 
a peculiar and similar appearance in the u 
G. Owen Rees. 
phosph: 
all 
MUCOUS MEMBRANE.—This term | 
been usually and properly restricted to th 
large expansions of membrane, in the int 
of the body, which are continuous ; 
external tegument: but it is impossible, in 
present state of knowledge, to treat of t 
apart from the true glands and the skin, w 
form with them a great system, to whicl 
generic term mucous will be applied im 
article. £ 
Many anatomists since the time of B 
have treated of the mucous membranes 
skin under the common title of tegume 
membranes ; and the opinion has been gi 
<< 
* Bonn, Specimen Anatomico-Medicum I 
&c. de continuationibus membranarum, &c. 
diforti Thesauro, tom, ii. p. 265. Roterod. 17 
