REPORT ON THE RADIOLARIA. CXXxiii 



in the two portions of the malacoma. It is sometimes possible, however, to recognise the 

 direct connection between them and to observe how the granules pass through the 

 openings in the capsule-membrane. 



208. Currents in the Endoplasm. Intracapsular circulation or a certain slow flowing 

 of the plasma within the central capsule is probably just as common in the Radiolaria as 

 without it, but it is not so easy to observe in the former case as in the latter. A more 

 satisfactory proof of these endoplasmatic currents is furnished by the arrangement of 

 the protoplasm within the central capsule, since this is (at all events in part) an effect 

 produced by them. In this respect the two main divisions of the class show charac- 

 teristic differences. In the Porulosa (the SPUMELLARIA, 77, and the ACANTHARIA, 

 78) the endoplasm is in general distinguished by a more or less distinct radial 

 structure, which is to be regarded as the effect of alternating centripetal and centrifugal 

 radial streams. In the Osculosa, on the other hand, this radial structure is absent and 

 the intracapsular plasmatic streams converge or diverge -towards the osculum or main- 

 opening in the central capsule which lies at the basal pole of its main axis, and through 

 which the mass of the endoplasm issues into the calymma. The two legions of the 

 Osculosa, however, present differences in this respect. In the NASSELLARIA (79) the 

 endoplasmatic currents appear to unite in an axial main stream at the apex of the 

 monaxon central capsule, and this apical stream seems to split into a conical bundle, 

 the individual threads of which pass diverging between the myophane fibrillse of the 

 podoconus towards the basis of the central capsule, and issue through the pores of the 

 porochora. In the PH^ODARIA ( 80), on the other hand, meridional currents of 

 endoplasm are probably present on the inner surface of the capsule, which flow from 

 the aboral pole of the vertical main axis to its basal pole, and return in the reverse 

 direction. 



209. Currents in the Exoplasm. Extracapsular circulation, or a distinct flowing 

 of the plasma outside the central capsule, may be readily observed in all Radiolaria which 

 are examined alive ; this is most readily seen in the astropodia, or those free pseudo- 

 podia which radiate from the sarcodictyum on the surface of the calymma into the 

 surrounding water. The granular movement is often quite as clear in the sarcodictyum 

 itself, and may be recognised in the collopodia, which compose the irregular plasmatic 

 network within the calymma. More rarely it is possible to follow the granular stream 

 thence through the sarcomatrix, and further into the interior of the central capsule. 

 In general the direction of the extracapsular protoplasmic streams is radial, and it is 

 frequently possible, even in a single free astropodium, to observe two streams opposite 

 in direction, the granules on one side of the radial sarcode thread moving centripetally, 

 those on the other side centrifugally. If the threads branch, and neighbouring ones 



