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, 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 
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 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 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 
