488 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
Giittulinopsis, however, being sessile or only short stalked, is kept 
running with great difficulty on cultures on account of the numer¬ 
ous bacteria which are certain to be transferred with the sorus and 
which interfere with normal development, so that, while studying 
these organisms, it was usually necessary to transfer them often to 
sterilized dung in crystallizing dishes. 
Drop cultures were made with filtered nutrient media, in van 
Tieghem cells, or on thin glass covers cemented to small petri or 
stender dishes by means of a mixture of vaseline and beeswax. 
Small, shallow stender dishes with a small amount of water in the 
bottom made especially favorable moist chambers for microscopic 
study. In examining drop cultures with high powers, such as 
immersion lenses, it was found that a sufficient amount of light 
could be directed through the culture dish and up the tube of the 
microscope only by use of a strong bull’s-eye’’ lens, placed so as 
to concentrate the light from a Welsbach gas lamp on the mirror. 
This method had some disadvantages in its heating effects, some¬ 
times causing the thin agar to soften and fall below the focus of the 
objective, but in general, it was. quite satisfactory. 
As killing media for both myxamoebae and fructifications, Flem¬ 
ming’s mixture, osmic vapor, acetic methyl green, and acetic gentian 
violet were used. One of the best nuclear stains for the vegetating 
myxamoebae proved to be acid Delafield’s haematoxylin, after killing 
for twenty-four hours with Flemming’s mixture ; while methyl green, 
following the fumes of osmic acid, also proved useful in this respect. 
Permanent mounts of all the sj^ecies found have been preserved 
in glycerin in which was dissolved a little eosin, and some were 
mounted in balsam. Since the sori are so extremely deliquescent, 
mature fructifications cannot easily be carried through the various 
processes for mounting in balsam ; young fructifications and pseudo- 
plasmodia, however, are sufficiently adherent to permit the use of 
such reagents. The species have also been preserved in a dry state, 
on dung or on agar dried slowly, or on paper on which the fructifi¬ 
cations have been formed, and type specimens as well as slides are 
preserved in the cryj^togamic herbarium of Harvard University. 
