THE RADIOLARIA 



95 



coloured fat, and reserve products. The extracapsular cytoplasm 

 is composed of (1) a thin, black, fatty assimilative layer or matrix 

 immediately outside the central capsule ; (2) a frothy mass of 

 mucilaginous and vacuolated substances secreted by interstitial 

 cytoplasm and forming the so-called "calymma" ; and (3) of fine 

 radiating pseudopodia which arise from the matrix and extend 

 freely into the water beyond the gelatinous bubbly layer. The 

 wall of the central capsule is perforated by minute, evenly dis- 



EP 



al 



FIG. 1. 



Thalassicolla (Thalassophysa) pelagica, Haeckel. x 25. CK, central capsule ; EP, extra- 

 capsular protoplasm ; al, alveoli, carbonic acid-holding vacuoles in the mucilaginous calymma 

 secreted by the protoplasmic network ; ps, pseudopodia. The minute unlettered dots are the 

 " yellow cells." (After Lankester.) 



tributed pores, and through these the intra- and extracapsular 

 cytoplasm are continuous. 



If the central capsule is shaken out of its calymmal covering 

 and kept under suitable conditions, its contents are capable of 

 regenerating the extracapsular cytoplasm within a week (Verworn 

 [14]). The first sign of this process is the protrusion of new radial 

 pseudopodia, which are completed in twelve hours. The basal 

 ends of these processes form or secrete a layer the matrix that 

 invests the central capsule, and their radial extensions secrete the 

 calymma. Finally, vacuoles make their appearance in the jelly 

 and the matrix becomes pigmented. In short, the extracapsular 



