401 
point, and so to leave also undecided the question as to how, 
from the differentiated Capsule-contents, the whole colony 
takes its rise. Here I will only notice two observations 
which make the direct development of the Capsule from the 
radiant Protoplasm very probable. The first fact was found 
by Stuart.!. In Collozoum inerme Stuart saw that a simple 
lump of thickened protoplasm became the seat of the develop- 
ment of new individuals. In this case small fat-drops are 
secreted from the clear protoplasm, which later unite them- 
selves in a central drop; further, there follows a division of 
the protoplasm into a clearer outer layer and an inner darker, 
which develops itself into the Capsule. The youngest stages 
of the latter were recognised as such by the presence of 
small polyhedral crystals, which are characteristic of the 
species investigated. I had no opportunity of proving these 
statements. 
The second fact, which appears to show that the capsules 
develop out of the radiant Protoplasm, I have myself often 
enough observed in Collozoum inerme. In place of the 
common layer of protoplasm which surrounds the capsules 
I often saw many vesicles, thickly pressed together, which 
possessed all the appearance of young capsules (fig. 24a). 
They were of various forms, often drawn out into sharply 
pointed processes, contained one or more oil-globules, and 
were caught in active division (fig. 24, 6,c). Around the 
entire mass of these little vesicles, bedecking the old Capsule, 
was spread a thin viscid coat, the remnant of the enclosing 
protoplasm of the Capsule. After some days I found the 
little vesicles in question in a cultivated Collozoum, scattered 
about on the surface of the colony, and rounded off. 
Further their development did not allow me to follow it. 
I conclude this notice with some remarks relating to the 
Yellow Cells. The writers who have busied themselves 
with Radiolaria regard the Yellow Cells as integral parts of 
these organisms, making not the slightest doubt about it. 
If we ask, however, what ground this conviction rests upon, 
all we get as an answer is, that the Yellow Cells always 
are present in most Radiolaria. The fact alone that in a 
given species the number of these said cells is subject to 
the greatest variations, and not seldom sinks to a very few, 
as well as that we possess no knowledge of the way in which 
they form themselves, is in itself sufficient to raise our sus- 
picions as to whether the yellow cells really belong to the 
Radiolaria. And if we take into consideration with what 
a remarkable constancy some parasitic organisms insinuate 
1 ¢Gottinger Nachrichten,’ 1870, No. 6. 
