Cytology and Movements of the Cyanophycee. 277 
omes of Cyanophycez to show the effect of the stain upon 
their nuclei. In every instance the nuclei of Spirogyra and 
the central bodies of the lower plants would give identical 
results. After as much was made out from the living 
preparations as possible, fixed and stained material were 
resorted to for the purpose of checking and supplementing 
the former observations. Any point thus noted would be 
again sought and found if possible in the living unchanged 
cell. 
But as is well known, fixed material is open to the criti- 
cism that artifacts may at times be formed. To overcome 
this it was thought that if several different fixatives sup- 
plemented by several different stains should each bring out 
the same features constantly, the strong presumption would 
be that the structures shown would be natural to the organ- 
ism, for in such a concert of results, obtained from such 
different chemicals and fixing methods, there would have 
to be some natural structure to act as a determining cause 
or there would certainly be differences shown in the fixed 
material. All of the experiments here detailed, and the 
results given, were thus confirmed. 
The Cyanophycee have usually been quite scientifically 
investigated, but in the study of the bacteria, where the 
cells are so much smaller and probably more delicate, some 
methods have been employed which would not be counte- 
nanced at all in higher forms, and even such methods have, 
at times, crept into the investigations of the Cyanophycez. 
The fixing reagents chosen were chromic acid of various 
strengths, chromacetic acid, corrosive sublimate—both hot 
and cold—picric acid in alcohol and in water, picro-sul- 
phuric acid, osmic acid, Flemming’s strong and weak fluids, 
Hermann’s fluid, acetic acid of various strengths, formalin, 
alcohol, formalin and alcohol mixed, and boiling in water. 
Staining was effected with Heidenhein’s iron-ammonia-alum 
hematoxylin, Delafield’s haematoxylin, acid hematoxylin, 
saffranin, eosin, erythrosin, methyl green, methyl blue (for 
