98 THE EVOLUTION OF CONTINUITY 



(consistently with our theory of sporosac-derivation) goes 

 hand in hand with an enormous development of the jelly 

 tissue lying between ectoderm and endoderm ; and, further, 

 the canals do not develop in contact with the manubrium, 

 and thus at first sight the parallel derivations of anemone 

 and gonophore are not apparent. With the help of Fig. 31 

 these points can be made more clear. 



Now the space marked X in Fig. 31, II, is of the greatest 

 importance, for in it we may recognise the basis, or antici- 

 pation, of what in higher living types is called the " ccelom." 

 This will be returned to later, but it may be said that in 

 animals classified as Ccelomata the " ccelom " is a space or 

 cavity which surrounds the alimentary tract, and is con- 

 tained by walls in which develop the supporting and muscular 

 tissues, the circulatory system, and the sexual elements. 



Fig. 32. — Imaginary drawing of a sea-anemone in section, 

 with open ccelomic space like the medusoid's. Compare 

 with Fig. 31, i. 



The space X is in fact the medusoid's " open ccelom " 

 surrounding the main alimentary tract of the manubrium ; 

 while in the walls of the space we have the jelly tissue of 

 the bell, the forerunner of the coelomata's muscles and con- 

 nective tissues ; in the radial and circular canal system 

 the forerunners of the true circulatory system of higher 

 types. It is also to be noted that the medusoid's sexual 

 elements are produced on the canals in the external walls 

 of the space, X, or on the walls of the space represented 

 by the outer surface of the manubrium. 



These suggestions, new and startling as they may appear 

 to the reader in the face of generally held opinion, will be 

 strongly supported when we come to higher types of living 

 Continuity. 



Had the primitive sea-anemone possessed a space like X, 



