The young cells at the end of the branches of these corallines contain quite immature polypi, yet the vulture-head attached to them, though small, are in every respect perfect When the polypus was removed by a needle from any of th cells, these organs did not appear in the least affected. Whe one of the vulture-like heads was cut off from the cell, th lower mandible retained its power of opening and closing Perhaps the most singular part of their structure is, tha when there were more than two rows of cells on a branch the central cells were furnished with these appendages, o only one-fourth the size of the outside ones. Their movements varied according to the species; but in some I neve saw the least motion; while others, with the lower mandibl generally wide open, oscillated backwards and forwards a the rate of about five seconds each turn, others moved rapidly and by starts. When touched with a needle, the bea generally seized the point so firmly, that the whole branc might be shaken.

These bodies have no relation whatever with the production of the eggs or gemmules, as they are formed before th young polypi appear in the cells at the end of the growin branches; as they move independently of the polypi, and d not appear to be in any way connected with them; and a they differ in size on the outer and inner rows of cells, I hav little doubt, that in their functions, they are related rathe to the horny axis of the branches than to the polypi in th cells. The fleshy appendage at the lower extremity of th sea-pen (described at Bahia Blanca) also forms part of th zoophyte, as a whole, in the same manner as the roots of tree form part of the whole tree, and not of the individua leaf or flower-buds.

In another elegant little coralline (Crisia?), each cell wa furnished with a long-toothed bristle, which had the powe of moving quickly. Each of these bristles and each of th vulture-like heads generally moved quite independently o the others, but sometimes all on both sides of a branch, sometimes only those on one side, moved together coinstantaneously, sometimes each moved in regular order one after another. In these actions we apparently behold as perfect a transmission of will in the zoophyte, though composed o thousands of distinct polypi, as in any single animal. Th case, indeed, is not different from that of the sea-pens, which when touched, drew themselves into the sand on the coast o Bahia Blanca. I will state one other instance of unifor action, though of a very different nature, in a zoophyt closely allied to Clytia, and therefore very simply organized Having kept a large tuft of it in a basin of salt-water, whe it was dark I found that as often as I rubbed any part of branch, the whole became strongly phosphorescent with green light: I do not think I ever saw any object more beautifully so. But the remarkable circumstance was, that th flashes of light always proceeded up the branches, from th base towards the extremities.

The examination of these compound animals was alway very interesting to me. What can be more remarkable tha to see a plant-like body producing an egg, capable of swimming about and of choosing a proper place to adhere to which then sprouts into branches, each crowded with innumerable distinct animals, often of complicated organizations The branches, moreover, as we have just seen, sometime possess organs capable of movement and independent of th polypi. Surprising as this union of separate individuals in common stock must always appear, every tree displays th same fact, for buds must be considered as individual plants It is, however, natural to consider a polypus, furnished wit a mouth, intestines, and other organs, as a distinct individual whereas the individuality of a leaf-bud is not easily realised so that the union of separate individuals in a common bod is more striking in a coralline than in a tree. Our conception of a compound animal, where in some respects the individuality of each is not completed, may be aided, by reflectin on the production of two distinct creatures by bisecting single one with a knife, or where Nature herself perform the task of bisection. We may consider the polypi in zoophyte, or the buds in a tree, as cases where the divisio of the individual has not been completely effected. Certainl in the case of trees, and judging from analogy in that o corallines, the individuals propagated by buds seem mor intimately related to each other, than eggs or seeds are t their parents. It seems now pretty well established tha plants propagated by buds all partake of a common duratio of life; and it is familiar to every one, what singular an numerous peculiarities are transmitted with certainty, b buds, layers, and grafts, which by seminal propagation neve or only casually reappear

Charles Darwin

All Pages of This Book