1921] PACK—JUNIPERUS 37 
Sterilization were easily and quickly removed. The bad seeds were 
floated off with water, and the good seeds rinsed and permitted to 
dry before sterilization. 
After some testing, a 5 per cent solution of formalin acting for 
2.5 minutes was selected as the best sterilizing agent for juniper 
seeds. It was found that formalin did not readily penetrate the 
coat, reduce the catalase activity, or hinder germination. The 
permeability of the coat was studied as follows. Seeds were sub- 
merged in different solutions for a definite time, removed, washed 
in distilled water, the coats removed, the seeds sectioned with a 
freezing microtome, and the sections tested for the respective solu- 
tions. Table III shows that the coat was very permeable to water, 
bases, and salts, but not permeable to stains and acids. 
TABLE II 
PERMEABILITY OF COATS TO WATER, STAINS, ACIDS, BASES, FORMALIN, AND SALTS 
Substance Permeability Substance Permeability 
Eosin (dilute)....... Impermeable LE ae ne Very permeable 
Kosin (strong)... ... I Cen. 3 Very permeable 
Neutral red (dilute). . Impermeable MAOH | oe Very permeable 
Staaten red (strong) .| Im pape 1 BUM anion ccs Permeable 
ARS aM Slowly permeable | NH,OH........-.} Permeable 
I N/ POG Very impermeable | AgNO,........... Very permeable 
H SO, PALtOS.. 23) Very impermeable | HgCl,..........-. Very permeable 
That the salts (AgNO, and HgCl,) penetrated the coats is 
shown by the catalase activity of the seeds with coats removed 
(table IV). These seeds, after being sterilized, washed, and incu- 
bated at 9° C. for 48 hours, had coats removed, and were ground 
for catalase activity determinations. It was further shown that 
AgNO, penetrated the coats by the fact that seeds so treated were 
killed. Seeds sterilized in formalin germinated, and therefore most 
of the seeds used in these experiments were sterilized 2.5 minutes 
in 5 per cent formalin. In this connection it should be noted that 
SCHROEDER (33) and Groves (14) found that the coat of the wheat 
seed was practically impermeable to AgNO,, and that this solution 
was a good sterilizing agent for wheat. This shows how the per- 
meability of seed coats may vary with different seeds. 
