IX COMPOUND ANIMALS 213 



apparently behold as perfect a transmission of will in the zoo- 

 phyte, 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, di'ew 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 

 organised. 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 

 beautifully 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 e.gg, 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 organisations ? 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 same fact, for buds must 

 be considered as individual plants. It is, however, natural to 

 consider a polypus, furnished with 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 body 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 reflecting on the production of two distinct creatures 

 by bisecting a single one with a knife, or where Nature herself 

 performs the task of bisection. We may consider the polypi in 

 a zoophyte, or the buds in a tree, as cases where the division of 

 the individual has not been completely effected. Certainly in 

 the case of trees, and judging from analogy in that of corallines, 

 the individuals propagated by buds seem more intimately related 

 to each other, than eggs or seeds are to their parents. It seems 

 now pretty well established that plants propagated by buds all 



