THE SUB-KINGDOM CCELENTEEATA. 7 



added. Throughout the entire of this department 

 the elements necessary for discharging the 

 function of true reproduction would appear to be 

 present. 



The power of emitting a phosphorescent light 

 is eminently possessed by several Coelenterata. 

 This is more especially seen among the oceanic 

 species which, together with Noctilv.ca, and other 

 floating organisms, serve to produce the luminosity 

 of the sea. 



The Coelenterate organism, therefore, has not 

 only a plan of structure, or relative position of 

 parts, peculiar to itself, but, viewed also as a mere 

 animal machine, is seen to be, physiologically, in 

 advance of the Protozoon. A comparison of the 

 ultimate morphology of the two groups may serve 

 further to elucidate this proposition. 



The body of the Protozoon, as elsewhere we have 

 sho^vn, consists chiefly of the elementary tissue 

 known as sarcode, or animal protoplasm ; a soft, 

 often transparent, elastic and extensile substance, 

 albuminous in composition, and presenting the 

 faintest traces of organisation. 



The sarcode body is also remarkable for the 

 manifold diversities of outward form wiiich it may 

 assume, though in many Protozoa there is little 

 which deserves the name of integument, and an 

 inner cavity, whether it exists under the form of 

 contractile vesicle or alimentary track, is rudi- 

 mentary in the highest degree. Some authors 

 consider the Sponges as Coelenterate, but the 

 aquiferous system of these animals, however other- 

 wise it may appear, is, in truth, lined by the outer 

 surface of the organism. 



B 4 



