The SPINAL MARROW, and the brain of the caterpillar, if it can be said to have any, seem to have very little relation to those of man; in the last, the brain is inclosed in a bony cavity; it occupies the greatest part of the head, and is anfractuose, and divided into lobes. There is nothing similar to this in the caterpillar; we find indeed in the head of that which we are describing, a part which seems to answer the purpose of the brain, because the nerves that are disseminated through the head are derived from it; but then this part is unprotected, and so small, that it does not occupy one-fifth part of the head; the surface is smooth, and has neither lobes nor anfractuousness; and if we must call this a brain, the caterpillar may be said to have thirteen, as there are twelve more such parts following each other in a line; they are nearly of the same size with that in the head, and of the same substance, and it is from them that the nerves are distributed through the whole body. Lest the idea of thirteen brains might be disagreeable to his readers, Lyonet has called these parts ganglions. The spinal marrow in the human species descends down the back, inclosed in a bony case; is large with respect to its length, and not divided into branches, diminishing in thickness in proportion as it is removed further from the brain. In the caterpillar, the spinal marrow goes along the belly, is not inclosed in any tube, is very small, forks out at intervals, and is nearly of the same thickness throughout, except at the ganglions. For a description of the numerous vessels, and curious texture of these parts, reference must be had to the original work of Lyonet. The substance of the spinal marrow, and of the ganglions, is not near so tender and easily separated as in man; it has a very great degree of tenacity, and does not break without considerable tension. The substance of the ganglions differs from that of the spinal marrow, as no vessels can be discovered in the latter, whereas the former are full of very delicate ones. The patient anatomist of the caterpillar has counted forty-five pair of nerves, and two single ones; so that there are ninety-two principal nerves, whose ramifications are innumerable.