M. Flourens on the Structure of Mucous Membranes; 379 
1. On the Mucous Membrane of the Nose, generally designated the Piru- 
irany Memprane.—LEyen up to the present day, the minute structure of 
this part is but little understood. About the middle of the seventeenth 
century, Schneider* completely overturned the erroneous and ancient 
notion which made the mucus descend from the brain, and demon- 
strated that it was the mucous membrane of the nose itself which was the 
true organ of the secretion. Shortly afterwards, Ruycht pointed out 
the distinction between the periosteum covering the nasal bones, and the 
mucous membrane which was wholly different. Haller was among the 
first who called attention to the epidermis of the pituitary membrane ; = 
but neither Bichat, nor Meckel, nor Béclard, though much later than 
Haller, make the slightest allusion to it. Bichat, like Ruych, seems to 
have recognised only two layers in the pituitary membrane, the one being 
the periosteum and the other the mucous layer.§ Meckel’s account 
corresponds with Bichat’s ;|| and Béclard only says, that “in certain 
parts—for example, the nasal fossa—the disappearance of the epithelium 
is gradual and insensible, so that it is impossible to assign precisely its 
limits.”41_ Thus Bichat and Meckel only dwell upon the chorion and the 
dermis of the pituitary membrane ; Béclard speaks only of the epidermis 
at the external margin of the membrane; and no one had previously 
pointed out that the Mucous body, that body and special Jayer which has al- 
ready been demonstrated in previous memoirs, and on which we are again 
about to insist, is invariably interposed in every mucous membrane be- 
tween the dermis and epidermis,—in popular language, between the true 
and the scarf skin. 
We repeat, then, that three layers, superimposed the one above the 
other, form invariably the mucous membrane ; and these three layers are 
very distinctly seen in the specimen No, 1 which I have now the honour. 
of submitting to the inspection of the Academy. It isa portion of the 
pituitary membrane of a horse. There will be observed, at the bottom of 
* Conradus Victor Schneider, De Catarrhis, &c. ‘Illa membrana pituitam con- 
dit, continet et emittit ;” lib. iii. cap. 8. 
{ And the perichondrium, which covers its cartilages. “Praterea considera- 
tione dignum judicio, septum narium cartilagineum, non solum investiri mem- 
brana mucosa, yerum quoque sub hac immediate membranula tenuissima. Hee 
continuatio est periostii, nasi partem osseam obducentis, atque perichondrum dici 
meretur.” Epist. viii. 
+ “ Quam habet sibi superjectam epidermidem,” he remarks (Elementa Physiol. 
&e. t. v. p. 144). It is curious that, as authority for this assertion, Haller quotes 
Winslow, whose account is contained in this confused phrase: “ Vers le bord des 
narines externes, la membrane pituitaire est trés-mince, et y parait comme un 
tissu dégénéré de la peau et de l’epiderme.” (Exposition Anatomique de la Struc- 
ture du Corps Humain; Traité de la Téte, No. 336.) 
§ “Un feuillet fibreux, qui est le perioste ou le périchondre de cavités nasales, se 
joint, dit Bichat, au feuillet muqueux pour former la membrane pituitaire. .... 
Le feuillet muqueux, dit-il encore, epais, spongieux et mou, est formé d’un chorion 
tres-prononcé qui lui donne cette epaisseur.” (Anatomie Descriptive, t. ii, p, 573.) 
|| Manuel de l’Anatomie, t. iii. p. 279. 
4 Eléments d’ Anatomie Générale, &e, p. 256. 
