397 
all that is essential nearly exhaustively treated in Miiller’s 
papers and Haeckel’s classical work, so that I may be very 
brief about this point. The Sphzerozoids and Collospheerids 
present us with aggregates of Capsules, which are held 
together by a common mass of Protoplasm. 
The Capsules are separated by a certain interval from one 
another; the Protoplasm binding them together consists of 
Alveoli (vesicles), of various sizes, between and on to which 
sarcodic threads and networks are disposed. I always found 
the capsules supported on the surface of the Alveoli, often 
lenticular, compressed, and enclosed by a radiating layer of 
Protoplasm, which also spreads itself over the Alveoli, and 
passed over continuously into the sarcodic envelope of neigh- 
bouring Capsules. Besides those Alveoli which carry cap- 
sules there are many smaller, which are free from Capsules. 
Lastly must be mentioned the Yellow Cells, which are 
scarcely ever wanting, and are found scattered in various 
positions, so that the chief soft elements of the compound 
Radiolaria are characterised by them. 
The Collosphere which I investigated in regard to their 
developmental history belong to the two species already de- 
scribed—C. Huzleyi of Miller, and C. spinosa of Haeckel. 
As has been long known from Miiller’s and Haeckel’s 
works, Collosphera possesses a fenestrated shell, which 
encloses a Capsule with protoplasmic investment. In the 
first named species the shell is smooth and furthest removed 
from the Capsule (figs. 2—4); in C. spinosa, it is beset with 
short spines (figs. 7, 8). The contents of the Capsule is, 
in both species, homogeneous—here and there of a faint violet 
colour, and contains a central oil-bubble. The Yellow Cells 
I have generally found united in a mass within the shell, 
although some also adhered to the surface of the fenestrated 
shell outside (figs. 7, 8). The young capsules are naked, 
embedded, without any shell), in a radiated protoplasmic 
sheath, not emarginated by any sharply marked envelope 
(fig. 1). In this stage they often divide themselves by fission 
into two halves. Not until maturer age does the Capsule 
obtain a resisting membrane, and become enclosed in a 
fenestrated shell (fig. 2). 
The changes which now further take place in the Capsule 
consist herein, that their entire content breaks up into a 
quantity of little spheroids (fig. 6 c). I was able to see this 
complete itself on the stage of the microscope in a single day 
in the case of C. Huzleyi. After a few hours many delicate 
vesicles appeared in the contents, which later broke up into 
smaller bodies (figs. 5,6). Unfortunately it is not possible to 
