214 
Journal of Agricultural Research 
Vol. XXIII, No. 3 
Only uninjured caryopses were used. In Sudan grass caryopses the 
iodin followed the same course as in Johnson grass caryopses but pene¬ 
trated at the proximal end nearly twice as rapidly. In all of the wheat 
grains black bands appeared round at least a part of the base of the 
embryo within 2 hours and spread within 24 hours around and under the 
embryos and a half or more of the way to the distal end of the grains. 
There were also local areas of penetration elsewhere in a few grains. 
All embryos at the same time became stained light brick red. In the 
corn, black areas appeared within a very short time, first at the dent then 
generally at various points scattered over the grain. At the end of 24 
hours a thin starch-stained zone just within the coat structures covered 
the entire grains except the thick hull at the extreme proximal end 
and sometimes a portion of the dent. 
It is evident, therefore, that even the easily penetrating iodin solution 
found access to the embryos of Johnson grass somewhat more difficult 
than to those of Sudan grass and much more difficult than to those of 
wheat and com. 
PENETRATION OP OTHER SOLUTES; POSSIBLE EFFECT UPON GERMINATION 
In 2-molar and 4-molar solutions of sodium chloride, freshly harvested 
Johnson grass caryopses behaved at first as if they were protected by 
semipermeable membranes, imbibing quantities of water which decreased 
with increasing concentration of the solutions, losing water when trans¬ 
ferred from the weaker solution with which they were in equilibrium to 
the stronger solution, and taking up water until they regained their 
previous weight when the reverse change was made. For some time 
they retained their viability when thinly covered with the salt solution, 
but by the end of several weeks they had taken up sufficient salt to kill 
all of the embryos. 
Immersion of the freshly harvested caryopses for seven days in molar 
solutions of potassium sulphocyanid (KCNS), sodium sulphocyanid 
(NaCNS), and lithium nitrate (LiNO s ) killed all of the caryopses; nearly 
all were killed by immersion for seven days in molar solutions of potas¬ 
sium nitrate (KN 0 3 ), sodium chlorate (NaC 10 3 ), barium sulphocyanate 
(Ba(CNS) 2 ), and urea (CO(NH 2 ) 2 ); about one-half survived seven days’ 
immersion in molar solutions of lithium suplhate (Li 2 S 0 4 ), barium nitrate 
(Ba(N 0 3 ) 2 ), magnesium nitrate (Mg(N 0 3 ) 2 ), and potassium tartrate 
(K 2 C 4 H 4 0 6 ). Molar solutions of other salts for the same length of time 
caused less injury, and immersion in water for seven days caused no loss 
of viability. 
Immersion of fully after-ripened caryopses for one or two days in 5 per 
cent acetic acid (CH 3 COOH), 5 per cent hydrochloric acid (HC 1 ), 5 per cent 
ammonium hydroxid (NH 4 OH), 3 per cent alcoholic potassium hydroxid 
(KOH), 95 per cent alcohol, acetone, ether, chloroform, or xylol killed 
all of the caryopses; immersion for one day in 3 per cent sulphuric acid 
(H 2 S 0 4 ) killed 80 per cent of them; and immersion for two days in satu¬ 
rated calcium chlorid (CaCl 2 ) solution killed 20 per cent of them. The 
controls soaked two days in water, were uninjured. All of the solvents 
or solutes mentioned in this paragraph increased the subsequent rate of 
bleaching of the thoroughly washed caryopses with Javelle water and the 
rate of penetration of iodin solution; hydrates had the most effect, fat 
solvents next, followed by acids and by (CaCl 2 ), which had very little 
effect. 
