484 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
Una rosea^ however, according to Cienkowsky, are able to germi¬ 
nate in water. The process of germination of the spores differs 
from the renewal of activity above described for pseudospores in 
the fact that the delicate cellulose spore membrane is ruptured by 
the swelling of the protoplasmic contents (pi. 6, fig. 40-44). In the 
case of the spores of Dictyostelium and Polysphondylium, in a few 
hours to several days from the time of sowing, the myxamoeba 
emerges, usually from the end, leaving the transparent cellulose wall 
behind as a ruptured sac. Rarely the slit in the wall extends the 
full length of the spore along one side, in which case the protoplas¬ 
mic contents come out from the side (pi. 6, fig. 44) ; while in 
Guttulina protea^ according to Fayod, the myxamoeba always ger¬ 
minates through a lateral perforation, evidently due to absorption 
and not to any rupture which has resulted from the swelling of the 
contents. 
Colored Forms of the Acrasieae. 
With the exception of OuttuUna rosea, which, according to 
Cienkowsky, possesses a reddish protoplasm, the myxamoebae of 
the various species of the Acrasieae are devoid of any appreciable 
color in the cytojdasm. The fructifications of several members of 
the group, however, although their pseudoplasmodium condition is 
uniformly whitish, assume some color during the formation of spores 
and the develoj^ment of cellulose walls. 
In one form, Gnttulinopsis vulgaris, the color of the sorus may 
be made to vary according to its dryness or the character of the 
substratum. When grown on horse dung, for example, the sori are 
at first usually whitish, and later, in drying, they uniformly assume 
a yellowish color; whereas, on an agar culture tube the sori at least 
when young, are, in my experience, uniformly white. It is possible 
that the yellowish color in the first case is due to the small particles 
which are carried up by the ascending colony from the horse dung 
surface, and drying may simply make the color more prominent. 
In certain species of the higher group of Dictyosteliaceae, there 
occur fructifications in which the color is a constant and well marked 
character. Those species which develop colored spores and stalks 
during the fructifying process are uniformly whitish during the 
