LATTICE WORKERS, OR POLYCYSTINA. 95 



maturity, the central capsule discharges the functions 

 of a sporangium, and its contents are broken up into 

 numerous flagellate swarm-spores, or zoospores. 

 After these have emerged from the ruptured capsule, 

 they probably pass into an actinophrys stage, and 

 then, after the formation of a jelly-veil into the con- 

 dition of sphcerastrum. Afterwards, when a mem- 

 brane is formed between the outer jelly-veil and the 

 inner nucleated cell-body, there is what has been 

 termed the actissa stage, which exhibits in its 

 simplest form the differentiation of the spherical 

 central body into central capsule and outer capsule, 



The zoospores generally arise in the following 

 manner: The nucleus of the central body breaks 

 up into numerous small nuclei, and each of these 

 surrounds itself with a small portion of the proto- 

 plasm. From the resulting small, roundish, or ovoid 

 cells protrudes one or more vibrating threads (vibra- 

 tile flagella). The fully-developed spores, which 

 commence their vibrations even within the central 

 capsule, emerge when it ruptures, and swim about 

 freely in the surrounding water by means of the 

 thread or flagellum. Their form is for the most part 

 ovoid, or rather cylindrical, sometimes spindle-shaped, 

 and from 4 to 8 /u in diameter. Immediately 

 behind the flagellum, at its base, liqs a spherical 

 nucleus, with . several small, flat granules in the 

 posterior portion. The number of vibratile flagella 



