EECEEATIVE SCIENCE. 



89 



which can here be noticed only in the briefest 

 manner. 



By Ehrenberg, one of their most distin- 

 guished investigators, they were considered 

 to be animals, and to this opinion he still 

 holds, ascribing to them stomachs and a 

 series of complicated internal organs, with 

 mouths and exsertile feet, Nearly all good 

 observers of the present day, however, agree 

 that erroneous interpretations have been put 

 by this eminent Prussian naturalist on much 

 of what he supposed he saw in them, and 

 are unanimously of opinion that their true 

 place is with the simpler tribes of the vege- 

 table kingdom, in which each individual is a 

 plant by itself, a simple cell. The strongest 

 objection to this view — that of their inde- 

 pendent motion — was discussed in the last 

 chapter, and another, their apparent com- 

 plexity of structure, will require after con- 

 sideration. "We have not been so fortunate 

 as to meet with the arguments of those who 

 propose to place them in a kingdom by them- 

 selves, that shall be neither animal, vegetable, 

 nor mineral, but a combination of the attri- 

 butes of all. The great point, however, on 



which such opinions must be based, the 

 possession in large quantity of the mineral 

 earth, flint, in their valves, appears to us 

 untenable with a reasonable knowledge of 

 the subject, derived less from books than a 

 minute and careful study of individuals as 

 they live and grow. This infiltration with 

 silex is assuredly a point of minor conse- 

 quence ; some of the higher plants have 

 tissues equally richly imbued with this 

 mineral constituent; as, for instance, the 

 external layers of cells in the sugar-cane, 

 the bamboo, and most, if not all, of the 

 grasses, probably some of the palms, and, 

 lower in the scale, the horse-tails (Equi- 

 setacese). In addition to this argument 

 against the proposed unnecessary separation 

 is one still more to the point, that the amount 

 of silex varies, according to species, indefi- 

 nitely. In some it exists in such quantity 

 as to render the valves hard and brittle as 

 glass, e. g., Pinnularia ; in others it is doubt- 

 ful if there be any at all, as in some of the 

 Schizonemas, of the more delicate Nitzschise, 

 and so through every gradation. 



TuFFEN West. 



THE KALEIDOSCOPIC COLOUE-TOP, 



BY JOHN GOEHAM:, ESQ., M.E.C.S., OF TUNBKIDGE. 



Have you not seen in the experiments with 

 Armstrong's electric machine, at the Poly- 

 technic Institution, a series of sparks passed 

 along a line of insulated conductors in close 

 proximity, which in their rapidity of passage 

 appeared like an unbroken stream of light ? 

 The lecturer has explained that the fluid 

 passes in distinct and separate flashes, and, 

 by a manipulation for the purpose, has 

 proved that such is the case. Yet, when his 

 regiment of brass knobs is properly arranged, 

 the sparks pass from one to the other in such 

 rapid succession that you cannot distinguish 



one from another, and you see a line of light 

 with apparently not a break in it. This is 

 sufficient to prove that we must not depend 

 wholly on the impressions conveyed to us by 

 our senses, and it also proves that apparitions 

 of objects remain on the retina of the eye 

 after the act of real vision is at an end. Go 

 into a factory and choose for experiment a 

 rapidly rotating fly-wheel. "When the ma- 

 chinery is at rest, paint the rim of the wheel 

 with zigzag lines of blue and Mhite, side by 

 side, all round, very distinctly, so that there 

 can be no question as to there being two 



