May 1908] 
Dictyostelieae or Acrasieae 
85 
pelled to take their places as rounds in the ladder, there does not 
appear to be any further use; only upon the most exalted indi¬ 
viduals is there conferred immortality. The ultimate purpose 
is the production of naked masses of resting bodies, the spores; 
these spores in some of the species are naked protoplasts, in 
others they are regularly invested with a cell-wall. The vary¬ 
ing details in the development of the fructifications furnish the 
characteristic differences for the genera and species. 
Mr. Olive’s studies make it clear that there is neither ho¬ 
mology nor analogy between the plasmodium of the Myxomy- 
cetes and the syncitium of the Acrasieae. The plasmodium is a 
complex protoplast, the cytoplasm of the individual amoebae fusing 
completely. The syncitium is a compound protoplast, an aggre¬ 
gation of individual protoplasts; at any stage in its development 
the colony may be separated into its component members. In the 
one there is continuous nuclear division, in the other no nuclear 
changes have been observed. Furthermore, the plasmodium is 
the final vegetative condition, while the syncitium is the initial 
fructifying stage. 
In Sappinia the resting stage consists either of a single 
encysted individual or of many individuals encysted in masses 
at the ends of projections of the substratum. It may be regarded 
as a transitional form from the true Amoebae. There are two 
species. 
In Guttulinopsis the spore-clusters or sori are usually 
stalked and composed of spores that have no cell-wall. This 
genus is represented by three species. 
Guttulina differs from Guttulinopsis in that the spores 
have a definitive protective cell-wall. It contains four species. 
The genus Acrasis is quite abnormal. It is defined as a 
chain of spores terminating a simple stalk. The spores in the 
single species are globose, the surface roughened and of a deep 
violet color; they are 10-15 mic. in diameter, much larger than 
in other species of the order. Its habitat is quite different too, on 
the sediment of beer. We much regret that Mr. Olive was un¬ 
able to find this singular organism. 
Dictyostelium is the principal genus both in the character 
of its development and in the number of its species. It has tall 
stalked sori sometimes more than a centimeter in height; the 
spores are invested with a cell-wall. There are seven species, 
two or three of them quite common. 
Polysphondylium is a branched form of Dictyostelium. It 
is possible that the distinction is not great enough to warrant the 
retention of the two as distinct genera. There are three species. 
In Coenonia the sorus is globular, borne at the summit of 
a stalk, which is dilated into a sort of cupule, in which the sorus 
is supported. One species. 
