130 
to be observed, also, that the granules of the central sarcode 
mass passed into these radiating pseudopods, and that the 
same game of granule-circulation commenced as I have de- 
scribed above in the full-grown Myxastrum. Now, too, 
already, small foreign bodies, which accidentally came in 
contact with the pseudopods, adhered to them, and were 
drawn slowly into the central mass of the body, to be there 
digested. Apparently these small radiating balls of *008 
mm. diameter already possess the form of the thirty to 
fifty times larger full-grown Myxastrum, and the latter can 
develop itself from the former by simple growth. Special 
processes of differentiation, or any other changes besides the 
simplest growth, are then no longer necessary. On some of 
the small Actinophrys-like germs which had taken food were 
also to be observed already, here and there, scanty ramifica- 
tions and anastomoses of the radiating pseudopods. On the 
other hand, as in the full-grown Myxastrum, neither vacuoli 
nor the differentiation of a nucleus existed in the uniformly 
homogeneous plasma-body. Under natural circumstances 
the encysted Myxastrum probably remains a long time before 
its cyst-membrane dissolves or bursts, and the first opportu- 
nity for further development is given to the siliceous spores. 
Apparently this development would not yet have taken place 
in the cysts which I examined if I had not artificially burst 
the covering. 
Myxastrum radians is, as follows from the foregoing com- 
plete picture of its generation-cycle, or of its individual (life- 
history) cycle of development, a Moner which, like Pro- 
tomyxa, Protomonas, and Vampyrella, appears during the 
course of its individual life in two different conditions — a 
motionless and a freely moving condition. In its freely 
moving condition, during which nourishment is taken, 
Myxastrum much resembles a true Actinophrys (A. sol.), and 
essentially differs from it only in the want of any vacuoli. 
In the motionless condition,, on the other hand, during which 
reproduction takes place, Myxastrum jn’esents a globular 
cyst, whose homogeneous plasma-contents break up by radial 
division (diradiation) into a number of motionless spindle- 
shaped spores. Each spore develops a siliceous covering, 
and then resembles a Navicula (without a nucleus). When 
the motionless condition changes again into the free-moving 
state the cyst bursts, the spores issue from their siliceous 
covering, and at once reassume the shape of a globular radia- 
ting Actinophrys-like plasma-body, which by simple growth 
changes into the form of the adult Myxastrum. 
