THE VOYAGE OF THE BEAGLE 217 



they differ in size on the outer and inner rows of cells, I have 

 little doubt, that in their functions, they are related rather 

 to the horny axis of the branches than to the polypi in the 

 cells. The fleshy appendage at the lower extremity of the 

 sea-pen (described at Bahia Blanca) also forms part of the 

 zoophyte, as a whole, in the same manner as the roots of a 

 tree form part of the whole tree, and not of the individual 

 leaf or flower-buds. 



In another elegant little coralline (Crisia?), each cell was 

 furnished with a long-toothed bristle, which had the power 

 of moving quickly. Each of these bristles and each of the 

 vulture-like heads generally moved quite independently of 

 the others, but sometimes all on both sides of a branch, some- 

 times only those on one side, moved together coinstantane- 

 ously; 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 of 

 thousands of distinct polypi, as in any single animal. The 

 case, indeed, is not different from that of the sea-pens, which, 

 when touched, drew themselves into the sand on the coast of 

 Bahia Blanca. I will state one other instance of uniform 

 action, though of a very different nature, in a zoophyte 

 closely allied to Clytia, and therefore very simply organized. 

 Having kept a large tuft of it in a basin of salt-water, when 

 it was dark I found that as often as I rubbed any part of a 

 branch, the whole became strongly phosphorescent with a 

 green light: I do not think I ever saw any object more beau- 

 tifully so. But the remarkable circumstance was, that the 

 flashes of light always proceeded up the branches, from the 

 base towards the extremities. 



The examination of these compound animals was always 

 very interesting to me. What can be more remarkable than 

 to see a plant-like body producing an egg, capable of swim- 

 ming about and of choosing a proper place to adhere to, 

 which then sprouts into branches, each crowded with innu- 

 merable distinct animals, often of complicated organizations? 

 The branches, moreover, as we have just seen, sometimes 

 possess organs capable of movement and independent of the 

 polypi. Surprising as this union of separate individuals in a 

 common stock must always appear, every tree displays the 



