42 Thomas Henry Huxley 



to rise again when the storm is over. This, and its 

 equall}' wonderful alHes, Huxley showed to be a com- 

 plicated colon\' of hydra-like creatures, each part being 

 composed of two membranes, and therefore essentially 

 similar to Medusae. Thus, by a great piece of con- 

 structive work, an assemblage of animals was gathered 

 into a new group and shewn to be organised upon one 

 simple and uniform plan, and, even in the most com- 

 plex and aberrant forms, reducible to the same type. 

 The group, and Huxley's conception of its structure, 

 are now absolutely accepted by anatomists, and have 

 made one of the corner-stones of our modern idea of 

 the arrangement of the animal kingdom. With the 

 exception of sponges, concerning the exact relations of 

 which there is still dispute, and of a few sets of para- 

 sitic and possibly degenerate creatures, all animals, the 

 bodies of which are multicellular, from the simple 

 fresh-water hydra up to man, are divided into two great 

 groups. The structure of the simpler of these groups 

 is exactly what Huxley found to be of importance in 

 the Medusae. The body wall, from which all the organs 

 protrude, consists merely of a web of cells arranged in 

 two sheets or membranes, and the single cavity con- 

 sists of a central stomach, surrounded by these mem- 

 branes, the cavity remaining simple or giving rise to a 

 number of branching canals. The members of this 

 great division of the animal kingdom are the creatures 

 which Huxley selected and placed together, with the 

 addition of the sea-anemones and the medusa-like 

 Ctenophora, which, indeed, he mentioned in his me- 

 moir as being related to the others, but reserved fuller 

 consideration for a future occasion. This group is 

 now called the Coelenterata, the name implying that 

 the creatures are simply hollow stomachs, and it is 



