Page:The American Cyclopædia (1879) Volume XV.djvu/329

 STAR STARCH 317 orders and the brighter stars of the first ten magnitudes are really intermingled in space, whence the fainter must be very much smaller than the brighter in these regions ; though of course this does not prevent us from believing that a certain proportion of the fainter stars are really far more remote than the brighter stars. The nebulae are found to be strewn in such a way that the second of the above laws is directly applicable to the relation between them and the fixed stars. For along the zone of the milky way few nebulae are found, and those belonging only to two orders, the irregu- lar (gaseous) nebulae and star clusters. The further we proceed from the galactic zone, the more richly do we find the nebulae scattered. This relation was first noticed by Sir W. Her- schel, but not thoroughly established until Sir J. Herschel had completed the survey of the southern heavens. Mr. Cleveland Abbe made a more exact analysis, in which he dealt with all the nebula in Sir J. Herschel's latest list, classifying them according to their resolvability, and showing that the density of nebular dis- tribution increased with the distance from the galactic zone for the irresolvable nebulae, but diminished with that distance for the clusters. These researches were statistical. The present writer has employed Mr. Abbe's tables in the construction of an equal surface chart of the nebulae, showing the law of their distribution to the eye. It is thus seen that there is not a gradual condensation of nebulae toward two opposite regions, near the poles of the galactic zone, but that the nebulae are gathered into streams, nodules, and irregular aggregations such as we find in the grouping of stars. We have said that law 2 characterizes the relation between stars and nebulae ; in other words, that their arrangement follows the law of contrast. There are two remarkable exceptions to this law, the Magellanic clouds. In these, where stars of all orders, from the ninth magnitude to irresolvable stellar aggregations, are as richly gathered as on the galactic zone, nebulae of all orders are also gathered richly, even more so than anywhere else over the whole heavens. It will be evident from what has here been shown, that the sidereal system is not the sim- ple scheme imagined by the earlier astronomers and still described in most of the text books of astronomy. No law of uniformity of distribu- tion can now be accepted, for one law after another has been disproved by the clearest possible evidence. Accidental numerical cor- respondences, found in the distribution of stars of various orders spread over large regions, cannot be admitted as evidence of uniform distribution of stars throughout surrounding space, or of any law of uniform condensation, when wo find on analysis that these relations "lave to be otherwise interpreted. We know, ! or example, that the excess of stars of the fainter orders is not- brought about by the jre extension of telescopic range, as Struve id Littrow have surmised, but has to be partly explained by the actually observed gathering of such stars in certain streams, clouds, sprays, and nodules of milky light. We must not allow any statistical rules (arbitrarily laid down in the first instance) to blind us to the facts thus disclosed. The future study of the sidereal system must in fine be based more exclusively on observation than heretofore ; though even more laborious processes of deductive reason- ing will have to be applied, since this, like all the greater problems of science, lies far be- yond the range of the purely inductive method. STARCH (also called amylaceous matter and fecula), a proximate vegetable principle exist- ing at certain periods of vegetable life in every plant that has been examined for it. It occuis especially in the seeds of cereals and other plants, in the tubers of potatoes, in tap roots, such as carrots and parsnips, in the pith of stems, as the sago palm, and sometimes in the bark. It is white, glistening, and pulverulent, composed of microscopic spheroids or gran- ules of a firm consistency, varying according to their origin from ^-$ to ^Vfr ^ an mcn ^ n diameter, and contained in the cells of the cel- lular tissue of the plant, several being enclosed in one cell. (See fig. 1.) According to Pay en, starch is found only when the nutriment is in excess, being consumed at the later stage of the vegetative process, when the nutriment becomes deficient. The young granules are exceedingly small, spherical, and homogeneous ; but in developing they become ovoid, lenticu- lar, or polygonal. They have a characteristic FIG. 1. Bean Starch lying in Cellular Tissue, magnified 200 diameters. FIG. 2. Starch Granules of tow UK mois, magnified 150 diameters. form and structure, being composed of a series of layers presenting the appearance of con- centric markings, which, in connection with the size, are characteristic of the plant to which they belong. Each granule is marked by a peculiar spot called the hilum, at which point it is attached to the cell wall in its early state. When viewed by polarized light, each granule is seen to be marked by a dark cross having its point of intersection at the hilum, as in fig. 2, representing the granules of tous les mois, a starch obtained from the tubers of the canna edulis, a plant belonging to the order marantacece, which includes also the maranta arundinacea or West India arrow root, fig. 3. When a plate of mica or selenite is interposed, to produce interference of light, the cross be- comes gorgeously colored. (See LIGHT, vol.