399 
Among the swarms of swimming zoospores lay many motion- 
less ones dispersed. ‘They were round or angular, with 
drawn-out points; their contents had the same composition 
as those of the motile zoospores ; in addition one or more con- 
strictions could be seen in them. Apparently they were 
developmental stages of the zoospores, obtained as they were 
in formation from the contents of the Capsule (figs. 13—15). 
The same appearances I obtained again in the other speci- 
mens of Collosphera, which I allowed to remain in the 
vessel for further “cultivation.” The movement of the 
zoospores lasted over twenty-four hours, then they dissolved 
away, leaving the little rod and the oil bubbles behind. My 
efforts to cultivate the zoospores in various ways, in order to 
bring them to a further stage of development, ended always 
in negative results. In spite of this, and although the 
further fate of the swarming cells remained undetermined, 
I believe I may consider them as zoospores. In favour of 
this view speaks their formation from the Capsule contents, 
which I, at any rate in the first stages, was able directly to 
observe on the object-slide in C. Huzleyi ; further, the bits 
of protoplasm caught in the act of constriction (ending in 
fission), which already contained the little rod which one so 
often finds in great quantity in the undivided Capsule- 
contents. These facts, as well as the normal appearance of 
the Capsule-content, make the supposition that we had here 
to do with parasitic monads, not admissible. When we have 
once obtained the conviction that swarm cells belong to the 
developmental cycle of the Radiolaria, some of the earlier 
statements, especially those of Haeckel as to Spherozoum, 
acquire a high significance. The vibrating vesicles with 
wet-stone shaped bodies, which this naturalist found in 
Spherozoum, were very probably identical structures with 
the zoospores of Collosphera. 
The second form of the colony-building Radiolaria in- 
vestigated by me was the common Collozoum inerme. The 
results here obtained agree completely in the chief points 
with the earlier results obtained by Haeckel. In some points 
they extend these, and on account of the facility with which 
one can observe what goes on in the Capsule-contents, they 
are well fitted to support not unimportantly the view here put 
forward. 
The Capsule is also in this case in the young stage devoid 
of an envelope, and imbedded in a radiant protoplasmic layer. 
They multiply by division, taking on the biscuit form or 
elongating in a worm-like form, and bending and then 
dividing by several constrictions into separate parts (figs. 
20, 23). 
