KECENT EESEARCHES ON THE RADIOLARIA. IGl 



Each zoospore is oval, '008 millim. long, and is provided witli 

 two long cilia. Each also contains a crystalline rod and a few 

 oil-drops*. Other zoospores were noticed which were angular 

 and without cilia, apparently immaturef- After twenty-four 

 hours all the zoospores died and dissolved away. These zoo- 

 spores were probably identical with the swarming vesicles found 

 by Haeckel in Splicer ozoum. 



In Collozoum Cienkowski found the capsules multiply by divi- 

 sion J, and containing often small crystalline rods as well as oil- 

 globules; but he deemed the occasional presence or absence of 

 these rods as a matter of no importance. He found the contents 

 of each capsule to break up into wedge-shaped or spheroidal 

 masses §, which then divided into small spheroids. As in Collo- 

 sjphcBraj so also here the colonies at this stage lose their alveoli, 

 while their capsules cohere and press together. Illness prevented 

 Cienkowski pursuing the investigation further ; but his observa- 

 tions confirmed Haeckel's as to young capsules being naked, 

 having, in fact, no central capsule. 



With a view to seeing whether yellow cells would produce them- 

 selves spontaneously, he followed Schneider in extruding Thalas- 

 «2CoZZa-capsules from their investing-mass. The capsules so ex- 

 truded developed themselves only so far as to produce pseudopodia. 

 He found, as before stated, yellow cells freely multiplying them- 

 selves in the dead body of a Collozoum colony. 



Schneider found || that he could keep Collozoum five or six 

 days in a cool temperature and by changing the water daily. He 

 also found that upon dividing a colony each part survived and 

 rounded itself off", and that two colonies placed in juxtaposition 

 became fused together in about twelve hours. The soft parts of 

 two adjoined Thalassicollce seemed to fuse together. 



Hertwig has published ^ by far the most complete and detailed 

 account of the Eadiolarian reproductive processes ; but even he 

 failed to keep the zoospores alive, so that we still remain ignorant 

 of the stages which may intervene between the zoospore larval 

 stage and that which approaches the mature condition. 



* Archiv, I. c. figs. 11 & 12, and Quarterly Journal, /. c. figs. 9 & 10. 

 t Archiv, I. c. figs. 16 & 17, and Quarterly Journal, I. c. figs. 14 & 15. 

 \ Archiv, I. c. figs. 25-28, and Quarterly Journal, I. c. figs. 20-23. 

 § Archiv, c. figs. 20 & 21. 



II Reichert und Du Bois Reymond's Archiv, 1867, p. 509. 

 % ' Zur Histologie der Radiolarien,' Leipzig, 1876. 



