Details of Protozoa. 57 



The Radiolaria are minute organisms with still more complex 

 skeletons, and are considered by Haeckel * to be more highly organ- 

 ized than the preceding order. They consist of a central portion 

 containing masses of minute cells, and an external portion containing 

 yellow cells. Here we have the first differentiation of parts in the 

 external coating and internal capsule, and side by side with this 

 differentiation we find colour more pronounced, and even taking 

 regional tints in certain forms. 



We may notice the following genera as exhibiting fine colour : — 



Red. Eucecryphalus, Arachnocorys, Eucrytidium, Dictyoceras 

 Yellow. Carpocanium, Dictyophimus, Amphilonche. 

 Purple. Eucrytidium, Acanthostratus. 

 Blue. Cyrtidosphaera, Coelodendrum. 

 Green. Cladococeus, Amphilonche. 

 Brown. Acanthometra, Amphilonche. 



Examples of these may be seen in the plates of Heeckel's fine 

 work, and as an illustration of regional decoration we cite Acanthos- 

 tratus purpuraceus, in which the central capsule is seen to run from 

 red to orange, and the external parts to be colourless, with red mark- 

 ings in looped chains. 



Spongocyclia also exhibits this regional distinction of colour very 

 clearly, the central capsule being red and the external portion yellow. 



The Spongida, or sponges, are, broadly speaking, assemblages 

 or colonies of amoeba-like individuals, united into a common society. 

 Individually the component animals are low, very low, in type, but 

 their union into colonies, and the necessity for a uniform or common 

 government has given rise to peculiarities that in a certain sense 

 raise them even above the complex radiolaria. Some, it is true, are 

 naked, and do not possess the skeleton that supports the colony, 

 which skeleton forms what we usually call the sponge ; but even 

 amongst these naked sponges the necessity for communal purposes 

 over and above the mere wants of the individual, raises them a step 

 higher in the animal series. A multitude of individuals united by a 

 common membrane, living in the open sea, it must have happened 

 that some in more immediate contact with the food-producing waters, 

 would have thriven at the expense of those in the interior who 

 could only obtain the nutriment that had passed unheeded by the peri- 

 pheral animals. But just as in higher communities we have an 

 * Hpeckel Die Eadiolarien, Berlin, 1862. 



