this phenomenon of Liesegangãs comes to the naturalistãs aid in explanation of rhythmic or zonary conôÙfiôÙgurôÙaôÙtions in organic forms, it has a special interest where the presence of concentric zones or rings appears, at first sight, as a sure and certain sign of periodicity of growth, depending on the seasons, and capable therefore of serving as a mark and record of the creatureãs age. This is the case, for instance, with the scales, bones and otoliths of fishes; and a kindred phenomena in starch-grains has given rise, in like manner, to the belief that they indicate a diurnal and nocturnal periodicity of activity and rest41.
That this is actually the case in growing starch-grains is generally believed, on the authority of Meyer42; but while under certain circumstances a marked alternation of growing and resting periods may occur, and may leave its impress on the structure of the grain, there is now great reason to believe that, apart from such external influences, the internal phenomena of diffusion may, just as in the typical Liesegang experiment, produce the well-known concentric rings. The spherocrystals of inulin, in like manner, shew, like the ãcalôÙcoôÙspheôÙritesã of Harting (Fig. 208), a concentric structure which in all likelihood has had no causative impulse save from