HELIOZOA 



739 



its own Barcode-substance; and thus a marked prominence is formed 

 (fig. 573, A, N), which gradually subsides as the food is drawn more 

 completely into the interior. The struggles of the larger animals, 

 and the ciliary action of Infusoria and Rotifera, may sometimes be 

 observed to continue even after they have been thus received into 

 the body ; but these movements at last cease, and the process of 

 digestion begins. The alimentary substance is received into one 

 of the vacuoles, where it lies in the first instance surrounded 

 by liquid ; and its nutritive portion is gradually converted into 

 an indistinguishable gelatinous mass, which becomes incorporated 

 with the material of the Barcode-body, as may be seen by the 

 general diffusion of any colouring particles it may contain. Several 



FIG. 574. Actinosphcerium Eichornii : m, endosarc ; r, ectosarc ; 

 c, c, contractile vacuoles. 



vacuoles may be thus occupied at one time by alimentary particles ; 

 frequently four to eight are thus distinguishable, and occasionally 

 ten or twelve ; Ehrenberg, in one instance, counted as many as 

 sixteen, which he described as multiple stomachs. Whilst the 

 digestive process, which usually occupies some hours, is going on, 

 a kind of slow circulation takes place in the entire mass of the endo- 

 sarc with its included vacuoles. If, as often happens, the body 

 taken in as food possesses some hard indigestible portion (as the shell 

 of an entomostracaii or rotifer), this, after the digestion of the soft 

 parts, is gradually pushed towards the surface, and is thence extruded 

 by a process exactly the converse of that by which it was drawn in. 

 If the particle be large, it usually escapes at once by an opening which 



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