434 
AMERICAN JOURNAL OF BOTANY 
[Vol. io. 
Acid fuchsin was another dye which did not yield as good results as eosin 
or Martius yellow. Used at a concentration of 1-4000 for 10 minutes, the 
staining was too weak to permit conclusions to be drawn. Used at a con¬ 
centration of 1-500 for 2§ minutes, on potato which had stood in the buffer 
mixtures of 0.002 M H 3 P 0 4 and 0.002 M NaOH about 6 hours, better 
results were secured. The pieces of potato did not stain uniformly with this 
dye, but irregularly, the vascular bundles taking the stain deeply. The 
potato discs from the acid solutions stained more heavily than those from 
the alkaline side, the line of separation appearing between solutions 6 and 7 
as for eosin and Martius yellow. The potato from the redistilled water 
stained about like that from solution 6. The potato from solution 2 showed 
the heaviest staining. 
The experiments with the basic dyes were considerably less satisfactory 
than those with the acid dyes. The potato from the different buffer mix¬ 
tures, as well as that from the redistilled water, took the basic stains so 
uniformly that little difference in intensity of staining could be noted in 
the potato from the different buffer mixtures. This was at first very 
puzzling. Microscopic examination of the potato stained with safranin 
or crystal violet, however, showed that these dyes stained the starch grains 
and cell walls heavily. The hydrogen-ion concentration of the solutions 
in which the potato had stood apparently did not noticeably affect the 
intensity with which the starch combined with the dye. The intensity 
with which the starch and cell walls took up the dye covered up to a large 
extent any other effect present. With eosin the starch grains were not 
stained, and only the protoplasmic content of the cell took the dye to any 
considerable extent. This offers what appears to be a satisfactory explana¬ 
tion for the better results secured with the acid dyes. However, sufficient 
positive results were secured with safranin, crystal violet, and methylene 
blue to satisfy us that the basic dyes were taken up more strongly by potato 
from the solutions of pH 6.95 and above. 
Confirmation of the conclusion that the basic dyes were taken up and 
heid more strongly by the potato from the alkaline solutions was obtained 
by the way in which the stain was lost from the potato after staining. Thus, 
discs of potato, after standing 2 hours in the 0.002 M H 3 PO4-0.002 M NaOH 
buffer mixtures, were stained for 5 minutes with methylene blue 1-18000. 
The pieces were a uniform blue after staining. They were then laid in 
15 cc. of the original buffer mixtures. After 2 hours the pieces from solu¬ 
tions 4, 5, and 6 were somewhat lighter in color than those from 7, 8 and 9. 
The difference, however, was not great. The buffer mixtures in which the 
stained potato had been washed were poured into test tubes, and the 
intensity of color was compared in the comparator. Those from the acid 
end were a deeper blue than those from the alkaline end. Thus 3, 4, and 5 
combined were a much deeper blue than 7, 8, and 9; 4 and 5 were much 
bluer than 7 and 8. Little difference could be noted between 7 and 8 as 
