The texture of the ganglions appears in nowise fibrous; there is absolutely no linear, filamentous appearance, &c. upon simple inspection. Homogeneous, if we may so say, in its nature, it presents every where an uniform aspect when cut in slices. However the celebrated Scarpa has considered the ganglions as resulting from a kind of expansion of the nerves, into an infinite number of extremely delicate fibres, which interlace with each other, and which become very distinct by maceration. I have not repeated all his experiments, which appear to me extremely difficult. I refer then to his work, and to the plates it contains. I would observe only that there is certainly something else in the ganglions, besides a simple division of the nerve into extremely fine threads. In fact, mere inspection is sufficient to establish between them the greatest difference. There is as evident a demarcation between the ganglions and the nerves, as between those of the brain and the brain itself. 1st. Difference of colour, reddish or greyish tinge in some, white in others; 2d. difference of consistence, of external qualities, &c.; 3d. difference of properties. If the nerves coming from the spinal marrow make only an expansion, in their passage, in the ganglions, by delicate filaments, there would then be only a difference of form and not of nature; the properties would be the same. Why then are they so different as I shall prove hereafter? Why, as a nerve goes from a ganglion, does it not communicate more voluntary motions? 4th. Why has not nature placed ganglions in the nerves of the extremities as in those of the other parts? If there is only a division of the nerve into finer filaments, in the ganglion, why is there not a proportion between the filaments that enter on one side, and those that go out at the opposite? In fact, those that enter into the superior cervical above, if they only expanded their filaments in this ganglion, and united afterwards to form those that go off below, would be equal in respect to size to those that go from it; all the ganglions would exhibit this constant relation between the nerves of one side and those of the opposite; now, it is sufficient to examine them to be convinced that an inverse arrangement exists. 6th. The ganglions ought always to be in proportion to the size of the nerves which form them by spreading their fibres. Why then are the intercostal ganglions so small, and the trunks that unite them, or rather that give origin to them and which go from them afterwards as we see in the usual manner, so large? Why on the contrary, is the superior cervical ganglion so large, and its branches so small? 7th. How can be explained the frequent interruptions between the ganglions in man, which are constant in many animals, if there is a continuity between the nervous filaments that enter the ganglions above, and those that go from them below? 8th. How does it happen that the ganglions and their nerves do not follow an exact proportion as to development with the cerebral nerves, if these form them by expanding? 9th. Why has not pain the same character in each species of nerves?