Page:Hardwicke's Science-Gossip - Volume 1.pdf/117

1, 1865.] even with his greatest care and contrivances he could seldom obtain them, without the mere pressure or friction in drawing them up through the water causing the pseudopodia to collapse and shrink, a change to take place in the oil-globules, as he calls them, of the sarcode, when death speedily ensued. He found, however, that in the globe, or bell-shaped species, such as the Eucyrtidiums, the sarcode substance was divided into four lobes or flaps (lappen); and Dr. Carpenter follows this idea in the very short notice he takes of Polycystina as a sub-order of Rhizopods. Müller says, in the inside of the shell the animal-substance consists of four folds arranged round a central axis, which reaches more or less deeply within the bell. The innermost part of these lobes contains one or more oil-like balls; and in the under-part, nearest to the open side of the shell, are some brown-yellow cells, and with them are also other cells or transparent spaces, or vacuoles, which have been conjectured to shadow forth the first incipient symptoms of circulation.

It would be too long to name all the various external shapes of the shells; but among the most striking differences of form may be mentioned that some are like numerous little globes growing out of each other, beginning with a small one at the apex, and each increasing in size as they descend, sometimes so gradually as to look like storied beehives piled up one on the other. In others, the globes or bells dilate greatly and rapidly towards the base, till the lowermost exceed in width the most outrageous crinoline! Then there are single round balls pierced through and through with spikes sticking out in all directions, but every pointing from the centre. Again, to compare small things with great, there are shapes of the Egyptian pyramids, and others stretched out and narrowed into obelisks.

Different from all these, are very numerous flattened disks, which appear to grow in concentric circles, some becoming bordered, other spiked round the edges, and many having very extraordinary radiating arms in endless variety.

A very remarkable feature in the Polycystins is their exuberant out-growths. Sometimes there are merely spines projecting in a tolerably regular, and always radiating manner; but sometimes these spines or projections branch out and subdivide in the most whimsical arborescent forms, so as to assume the shapes of stags' antlers, or even the more complicated delicate branchings of the once famed bedeguar of the rose (which we used to seek out in childhood's days, and call Robin-redbreast's pillow). Apparently these spines of the Polycystms, whether simple or compound, always are to a certain extent hollow, so as to have been permeated by the sarcode substance during their growth; sometimes instead of becoming finely attenuated, they become bulbous at their points; and these bulbils swell, become cellular or foraminated, and assume very much the appearance as if they were gemmæ from the parent, and intended to break forth and commence life as fresh individuals. Very remarkable instances of this simulation of "continued gemmation," as described by Dr. Carpenter as an attribute of the newly-discovered Eozoon of the Canadian rocks, occur in the Polycystinic forms called by Professor Ehrenberg Astrommas and Stephanastrums: in these a central spheroid body is enveloped by a sort of fine siliceous web or sponge, which gradually breaks away as the centre sends forth stalks (three to six, but normally four), celled and chambered as complicately as any foraminifer; and pushing their way through the sponge-like envelope and beyond it, their ends become club-shapes, often strongly spiked at the extremity, but the swollen part containing what looks like a reduplication of the central parent-form; and these seem as if they might possibly break away, and become in their turn centres of growth.

If comparatively but few of these organisms have been systematically examined in a living state, countless multitudes of their skeletons have been re-