LATTICE WORKERS, OR POLYCYSTINA. 101 



certain differences in the two portions. It is not so 

 easy to observe the movements within the inner 

 capsule as without it, but it is sometimes possible to 

 observe the granules pass through the openings in 

 the capsule membrane. A distinct flowing of the 

 plasma outside the central capsule may be readily 

 observed in all Radiolaria in the living state. This 

 is most easily seen in the free pseudopodia, which 

 radiate from the surface into the surrounding water. 

 In general the direction of the streams is radial, 

 and it is frequently possible to observe two streams, 

 opposite in direction, the granules on one side of the 

 radial thread moving outwards, whilst those on the 

 other side move inwards. If the threads branch, and 

 neighbouring ones become united by connecting 

 threads, the circulation may proceed quite irregularly 

 in the network thus formed. The rapidity of the 

 currents is subject to considerable variation. 



In addition to the interior movements of the plas- 

 matic currents, there are also two groups of motor 

 phenomena which may be observed, the contraction 

 of individual parts, which produce modifications of 

 form, and the voluntary or reflex motion of the whole 

 body. Active locomotion, which is perhaps volun- 

 tary, occurs in three modes : (i) The vibratile move- 

 ment of the flagellate swarm-spores, (2) the swim- 

 ming of the floating organisms, (3) the slow creeping 

 of those which rest accidentally upon the bottom. 



