218 M. M. Mercaur 
the color of the endosare stain but does not seem to make it more 
red or to give it a violet tone. The substance in the endosare 
which stains seems for the most part to be in solution, though here 
and there dense irregular masses are seen which seem as if 
coagulated. The endosare spherules also stain, but less strongly than 
the protoplasm. 
Individuals of Nyctotherus and Balantidiwm on the same slides 
with the O. ranarum and O. caudata show no reaction to potassium 
iodide. With iodine dissolved in a water solution of potassium iodide 
they show dark brown bodies in the endoplasma, the endoplasma 
itself, like the ectoplasma, being merely tinged with yellow. 
Frscuer (1905) has described a method of treatment which he 
says gives a distinctive stain for glycogen. The tissue containing 
the glycogen is fixed in absolute alcohol, sections are made by the 
paraffin method, these are brought through graded alcohols into a 
ten percent solution of tannin (to precipitate the glycogen) and are 
then placed in potassium bichromate to render this precipitate 
insoluble in water. Ofter washing the sections they are stained in 
safranin, only the glycogen bodies becoming red, the cytoplasm and 
nuclei being hindered from staining by the treatment with tannin. 
I tried this stain upon sections of O. dimidiata. The rectum of a 
Rana esculenta was opened and the contained Opalinas and Balantidiums 
were divided into two parts, one lot being fixed at once and stained 
according to Fiscuer’s directions; the other lot was kept two days 
in a solution of sodium chloride until the infusoria were mostly 
inactive, then they were fixed and stained by the same method. In 
the sections of the first lot of Opalinas, killed before starving, the 
ectosarc spherules were a bright red. In most individuals the 
endosarc was wholly unstained: in other individuals the endosare 
was strongly stained, great irregular red masses, of what appeared 
like coagulated material, completely filling it; in still other individuals 
but little color and few masses of coagulum were seen in the endosare. 
The endosare spherules were usually unstained but in some animals 
with well stained endosare and coagulum the endosare spherules 
were also stained, but showed a fainter red than the protoplasm. 
In the sections of Opalinae which were starved forty-eight hours 
before killing and staining, the ectosare spherules were stained as 
strong a red as in the other sections. In almost all individuals the 
endosarc was wholly unstained; a few individuals, on the other 
hand, showed red masses of coagulum in the endosarc, the whole 
endosare being stained. In all the Opalinas on this second lot of 
