460 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
For the most part, fumes from osmic acid solution placed in the 
bottom of a culture cell, sometimes followed for a few minutes by 
Flemming’s weaker solution placed directly on the object, were used 
as killing reagents ; acetic methyl green also proved useful as a kill¬ 
ing and staining agent. The mucus which causes the myxamoeba 
to adhere to the substratum usually serves to hx the individual, when 
extended, firmly to the agar or cover glass surface; but when 
rounded as while undergoing the division subsequently described as 
resembling indirect division, the bodies are readily washed away 
and lost. Consequently, such reagents as Flemming’s triple stain, 
or other stains by which the achromatic portion of the nucleus might 
be differentiated, could rarely be used with much success. Tempo¬ 
rary stains and mounts, therefore, were for the most part utilized in 
studying the internal structures of the developing myxamoebae. 
In following out the nuclear phenomena of these organisms, two 
types of nuclear and cell division seemed to be distinguishable, one 
of which occurs shortly after germination, while the second occurs 
during the subsequent active vegetative condition. The first, or 
primary division, as I have called it, which, so far as 1 have observed, 
takes jjlace very slowly and mostly at night, is preceded by certain 
prolonged internal changes that closely resemble indirect division, 
while the secondary division invariably occupies but a few minutes 
and the nuclear phenomena rather resemble direct division. Fur¬ 
thermore, while the secondary division is the one usually observed 
and may evidently be repeated a number of times for the same 
individual, I have been unable to decide definitely whether the 
first division, which has only been observed immediately after ger¬ 
mination, is a necessary phenomenon in the life history of the indi¬ 
vidual, or whether it is only an occasional phenomenon. 
For purposes of comparison, I have examined the resting nuclei 
in the Myxomycetes in some detail throughout the vegetative stage, 
both in the isolated individuals and in plasmodia, and have failed 
to find any close resemblance to the corresponding conditions in the 
Acrasieae. Although extremely small, the nuclei, in their structure 
as well as in their indirect division, appear to correspond, in essential 
features with the complicated conditions observed in higher organ¬ 
isms. Lister (’93) also asserts that the nuclei of the vegetative 
conditions of the Myxomycetes are of the usual type and that they 
undergo karyokinetic division, preceding the division of the individ- 
