st to
the individual peculiarities. He shewed that microscopically all the
complicated systems of canals and organs were composed of two
"foundation-membranes," two thin webs of cells, one of which formed
the outermost layer of the body, while the inner formed the lining of
the stomach and canals in the thinner parts of the body, such as the
edges of the umbrella-like disc, and towards the ends of the
tentacles. These thin webs formed practically all the body. In the
thicker parts there was interposed between them an almost
structureless layer of jelly, placed like padding between the lining
and the cloth of a coat. He shewed that blood-vessels and blood were
absent, in which he has been confirmed by all other observers. He
declared more doubtfully against the existence of a special nervous
system, and it was not until long after, when the methods of
microscopic investigation were much more perfect, that the delicate
nerve-cells and nerve-fibres, which we now know to exist, were
discovered.

Having thus shewn the peculiar organisation of the group he turned to
seek out its allies among other families. The Medusae consisted
essentially of two membranes inclosing a variously shaped cavity
inasmuch as all its organs were so composed. The generative organs
were external, being variously developed processes of the two
membranes. The peculiar organs called thread-cells--poisoned darts by
the discharge of which prey could be paralysed--were universally
present. What other families presented these peculiarities?

There are to be found abundantly in sea-water, and less frequently in
fresh water, innumerable forms of animal life called Zooephytes or
animal plants because they occur as encrusting masses like lichens, or
branched forests like moss, on the surface of stones and shells. A
common habit gave this set of creatures their common name; but,
although they were grouped together, there was no greater affinity
among them than there is racial affinity among people who clothe
themselves for an evening party in the same conventional dress. Huxley
examined a large number of these, and picked out from them two great
families of polyps, the Hydroid and Sertularian polyps, which each
consist of colonies of creatures very much like the little fresh-water
hydra. He shewed that the tubular body of these and the ring of
tentacles surrounding the mouth were composed of the same two
foundation-membranes of which all the organs of Medusa