No. 6.—MONOGRAPH OF THE ACRASIEAE. 
BY EDGAR W. OLIVE. 
The organisms which form the subject of the present paper were 
first brought to the attention of the writer while studying in the 
cryptogamic laboratory of Harvard University during the winter of 
1896-’97. At the suggestion of Professor Thaxter an attempt was 
made to examine in some detail the morphology and development 
of the members of the group as well as to revise it from a system¬ 
atic standpoint. With this end in view, a large amount of mateiial 
was accumulated from various sources, which forms the basis of the 
following account. 
Although the time at the writer’s disposal has for the past five 
years been greatly curtailed by other duties in the University, the 
inevitable delay in completing the work has been of advantage in 
that it has enabled him to keep a majority of the forms considered 
under observation during this period and thus to determine the con¬ 
stancy of the characters which distinguish the different species. 
With a few exceptions, which will be hereafter noted, the material 
has been derived from laboratory cultures of dung and other sub¬ 
stances that form the natural substrata on which the Acrasieae 
develop, and the different forms thus obtained have been cultivated 
in a pure condition, in gross, on the natural substratum previously 
sterilized, as well as in nutrient agar tubes and hanging drop cul¬ 
tures. Although the number of representatives previously recorded 
has thus been nearly doubled, several of the species described by 
European writers still remain unknown except through the original 
diagnoses, wUich are with one or two exceptions, not only very 
meagre but unaccompanied by figures. Having been unsuccessful 
in obtaining by correspondence further information concerning these 
doubtful forms, I am unable to add anything to the scanty informa¬ 
tion already available concerning them. 
I wish to acknowledge my indebtedness especially to Professor 
Thaxter, for material from various localities, and for advice and 
assistance in the preparation of this paper. His collection of 
Acrasieae from New Haven and from Florida has been given me 
