With the question of the ganglionic struc ture of this body has necessarily been mixed up that of the course taken by the nerves which arise from it, and their relation to the facial. Indeed, the negative side of the ar gument —the denial of the ganglion — perhaps requires its advocates to explain the real nature of the swelling, and to show the ar rangement of its supposed constituent nerve fibres. But in the present day at least, the affirmative of the question may be justifiably reduced to the detection, in the so-called ganglion, of the globular vesicles which are essential to the structure of a nervous centre.
It is singular that for a considerable time this simple method of settling the disputed nature of the intumescence should either have escaped notice or failed to afford any satisfac tory results : the latter seems to have been sometimes the case ; but more frequently, perhaps, this method of proof or disproof was overlooked. The discovery of the ganglion corpuscles, and thus the establishment of its ganglionic nature, belongs to Morganti. He describes it as consisting of meshes or reticu lations of nerves, the intervals of which are filled by a yellowish ash-coloured substance. In the latter, he states himself to have verified the existence of these bodies.
The essential part of this description I am able to confirm. It appears difficult to obtain specimens from the human subject in a state sufficiently fresh to observe these delicate and easily decomposed corpuscles. In the lower aniinals, however, this difficulty is no longer met with ; and many of them present the additional advantage of a much less dense neurilemma than that which is present in the human structure. After removing the brain of the sheep, the ganglion may thus be easily exposed and removed, preferably with the nerves still attached to it. Cutting off the attached extremities of these, and very gently and imperfectly tearing up the ganglion which remains, completes the preparation of the specimen. Under these circumstances, the corpuscles of the grey matter are readily visible. They are of an oval or roundish shape, and of a very large size, which amounts in the average to about the 1-200th of an inch. In the uninjured parts of the specimen, they appear to be disposed vvith considerable regu larity, each being in contact with several others by a part of its surface. On a rough calcula
tion, the ganglion contains about three or four hundred of these corpuscles. The contents of the corpuscles are of the ordinary- kind. A nucleus occupies some portion of their inner surface, and a large quantity of the usual granular substance fills up the remainder of their interior. Most of them also contain a quantity of pigment towards one extremity of their ovoid cell-cavity. This is disposed as a dark brown mass of an oval form, and some of these masses, when seen isolated by the accidental rupture of their containing vesicles, have exhibited a defined and sharp outline, which induces me to suspect their inclusion in a cell membrane, separating them from the rest of 'the contents of the vesicle. Rarely there are appearances of short processes from these vesicles. Nerve tubules in rather spar ing quantity- are found in contact with these large cells, mostly occupying their interstices, or eoiled around their circumference ; and the periphery of the ganglion itself is surrounded by a kind of layer of them : these appear ances, however, seem distinctly traceable to the mechanical violence employed in the examination, which forces the tubes into the situations of least pressure ; and one cannot, therefore, regard them as affording the least insight into the mode in which the nerves are arranged with respect to the vesicles. ' From this ganglion emerge, or rather to it are attached, the following branches : — 1. and 2. The superficial petrosal nerves, the greater of ivhich (fig. 405, h ) passes to the ttpheno-palatine, and the lesser (i) to the otic ganglion : the first of these Morganti has de picted receivina a filament (k), which comes frotn the facial, and in its course to the pe trosal nerve passes over the ganglion without joining it. The second or lesser of the two appears to be derived solely from the ganglion. 3. A large branch (in) which forms the great bulk of the chorda tympani ; but, in order to this, is also joined by one or two filaments (n) from the facial nerve, which accompanies it in the Fallopian canal. 1. Branches (/) which passing downwards are lost in the trunk of the portio dura.