380 M. Flourens on the Structure of Mucous Membranes. 
the preparation, the dermis, all furrowed with lines, arranged like the . 
markings of a leaf; above the dermis is a fine membrane, which is the 
mucous layer or the mucous body ; and above the mucous body is a layer 
finer still, which is the epidermis. The dermis, then, together with the 
mucous body and the epidermis, exist united, and superimposed the one 
above the other, in the mucous or pituitary membrane of the nose. 
2. We now proceed to the Mucous Membrane of the Windpipe.—The 
structure of this new membrane has not been better described, nor is more 
accurately understood, than that of the pituitary membrane. Haller admit- 
ted that it possessed an epidermis,” and Bichat denied it. Bichat says ex- 
pressly, “In no part of the mucous membrane of the air-passages, can the 
existence of the epidermis be demonstrated.” t In opposition to this state- 
ment, I here exhibit, in the specimens Nos, 2 and 3, the epidermis, and 
the mucous body, and the dermis of the mucous membrane of the wind- 
pipe. These two specimens are two portions of the windpipe of the horse. 
The epidermis is exhibited in the former. It has been removed in the 
latter ; but still two detached and superimposed layers remain—the ante- 
rior is the mucous layer or body, the posterior is the dermis. Hence, then, 
the mucous membrane of the windpipe, like that of the nose and all other 
mucous membranes I have hitherto examined, possesses a dermis, 2 mu- 
cous body, and an epidermis. 
8. It is the same with the Mucous Membrane of the Bladder. ‘The spe- 
cimen No. 4. which I now exhibit, is the bladder of a rabbit ; and any 
one may clearly perceive three distinct layers, all of them very delicate, 
and superimposed the one above another. The anterior, or the most de- 
licate, is the epidermis ; then follows the mucous layer, and then the der- 
mis, and behind the dermis is the membrane, or rather the muscular layer 
of the viscus. The epidermis of the bladder had been previously observed 
by Haller ;t it had also been noticed by Ruych ;§ but both of these emi- 
nent men had seen it only as the result of lesions and diseases of the 
* “Epidermis est levis, sui similis, simplex. . . . Eam in funesta puerorum an- 
gina frequenter xgroti reddunt.” (Elem. Physiolog. t. iii, p. 148.) 
+ Anatomié Descriptive, t.iv. p. 56. “ L’unique preuve, ajoute-t-il, que l’on puisse 
acquerir ici de l’existence de l’epiderme, se tire des cas pathologiques ou des frag- 
ments membraneux on été rendus par expectoration. Waller en cite plusieurs, 
et n’admet que d’apres cela un epiderme muqueux pulmonaire. Mais cette preuve 
est insuffisante, ces lambeux pouvant étre analogues aux escarres plus ou moins 
profondes produites sur la peau par les brilures,” &c. 
* Membrana vesice nervea . . . ex cute evidentur continuata, precipua est 
vesice tunica. . . . Intima membrana, levissima . . . tenuior quam ner- 
vea, epidermidis est propago. . . . Cum epidermide, cui continuatur, id habet 
commune, ut secedat de nervea, de quo corpore exeat, . . . et perinde renas- 
catur.” (Elementa Physiologie, &c. t. vii. p. 326.) 
§ “ Pauca superaddi de interiore membrana, que vesice urinariz cavitatem uri- 
ne contiguam facit. De qua imprimis notasse juvet portionem ejus, a reliqua se- 
paratam posse per vias urine excerni. (Adversarior Anatomic. Decas secunda, 
p. 24.) 
