222 REMINISCENCES OF HUXLEY 
a motley multitude, about which there was a prevail- 
ing confusion of ideas at the time when young Huxley 
began the study of jellyfish. 
We all know how it was the work of the great 
Esthonian embryologist, Baer, that turned Herbert 
Spencer toward his discovery of the law of evolution. 
It is therefore doubly interesting to know that in these 
early studies Huxley also profited by his knowledge of 
-Baer’s methods and results. It all tended toward a 
theory of evolution, although Baer himself never got 
so far as evolution in the modern sense; and as for 
Huxley, when he studied Medusz, he was not con- 
cerned with any general theory whatever, but only 
with putting into shape what he saw. 
And what he saw was that throughout their de- 
‘velopment the Medusz consist of two foundation 
membranes, or delicate weblike tissues of cells, — one 
forming the outer integument, the other doing duty 
as stomach lining, — and that there was no true body 
cavity with blood-vessels. He showed that groups ap- 
parently quite dissimilar, such as the hydroid and ser- 
tularian polyps, the Physophoridz and sea anemones, 
are constructed upon the same plan; and so he built 
up his famous group of Ccelenterata, or animals with 
only a stomach cavity, as contrasted with all higher 
organisms, which might be called Ccelomata, or animals 
with a true body cavity, containing a stomach with other 
viscera and blood-vessels. In all Ccelomata, from the 
worm up to man, there is a third foundation membrane. 
Thus the Cuvierian group of Radiata was broken up, 
and the way was prepared for this far more profound 
and true arrangement: (1) Protozoa, such as the amoeba 
and sponges, in which there is no distinct separation 
