Page:A descriptive catalogue of the Warren Anatomical Museum.djvu/149

 of qualities or forms. Studying the subject in the most general manner, there are striking resemblances between the distribution of matter capable of assuming a polar condition, and free to move around a magnet, and the dis- tribution of matter around the nervous axis of an em- bryo.

" In every complete series of magnetic curves there are two neutral lines, one extending lengthwise of the magnet, so that the curves formed are divided into right and left ; secondly, a transverse one, the particles on each side of, which are known as forming the north and south curves. In the right and left series, those which are on one side of the magnet are symmetrical with those on the other, but not in themselves ; and in the north and south series those on either side of the transverse neutral line are sym- metrical with each other, but not in themselves. Thus we have in the first case something analogous to right and left or bilateral symmetry, and in the second to fore and hind symmetry.

"If two magnets are placed parallel to each other and at a distance, then two complete sets of curves are formed in the usual way ; but if they are brought so as to be within each other's influence, the magnetic figure now becomes a compound one, the central portion of which consists of the united curves from the two adjoining sides of the magnet, and the particles from either series of the curves do not pass beyond the line where the forces of the two magnets are in equilibrium.

" If the magnets are now inclined towards each other so as to touch at one end, having a V-shape, then we shall have the particles arranged so as to produce a figure double in front but single behind. The ends which are separated will arrange the particles so as to form a double series of curves, independent of each other ; but as the magnets come nearer together, the curves begin to press against each other, and an intermediate symmetrical figure is formed.

" The distribution of matter in animals having bilateral symmetry, both in normal and abnormal development, is analogous to the series of distributions just described.

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