ON THE POISONOUS ACTION OF DI-CYANOGEN. 
39 
be distinctly seen that HCN was less noxious than di-cyanogen. 
In a dilution of i : 100000 of di-cyanogen Spirogyra, Oscillaria 
and Diatoms were seen alive after several days. 
Action of Di-cyanogen and Hydrocyanic 
Acid upon Phænogams. 
In a solution of prussic acid i : 1000 which had no reaction 
upon litmus paper, some young radish plants 4 cm. high were 
placed. After 15 hours, leaves and stem had withered, lost 
the turgor, and commenced to dry up. Di-cyanogen solution of 
i : 5000 acted almost as quickly upon young barley plants with 
stems 10 cm. high. Even in a solution of di-cyanogen of 1 : 10000 
young barley plants 5—6 cm. high were attacked after 3 days, 
turned yellowish, and commenced to dry up. In 200 c.c. of cy¬ 
anogen solution i : 25000, to which were added the necessary 
mineral salts in the usual proportion, was placed a young water- 
cultured lupin-plant with a stem 8 cm long. After 20 hours the 
stem was bent down, and also the leaves without any turgor. 
After further 15 hours, however, the plant seemed to recover, but 
only for a short time, for 20 hours later the plant commenced to 
dry up. In another experiment, a stem of Narcissus (N. tazetta, 
var. chinensis, Eoem.) was cut immediately above the bulb and 
placed in a solution of di-cyanogen in 1 : 10000. In this case no 
noxious effect was observed, evidently there was so much dis¬ 
solved albuminous matter encountered in the juice by the cyano¬ 
gen that this poison could not reach enough cells to kill the plant. 
Some experiments were made with seeds that were just 
beginning to germinate after having been soaked in water. Thus 
the seeds of peas, turnips, radishes, and barley were treated 
with cyanogen-respectively hydrocyanic acid solution of 1 : 5000, 
in each case 12 seeds being placed in 50 c. c., and left to stand 
for 3 days in closed vessels. Control experiments with distilled 
water were also made. After pouring off the liquid, the vessels 
were left to stand at 15 0 —20°C ; after 24 hours great differences 
were noticed : in the control experiments the seeds developed in 
the normal way, the others, however, remained stationary 1 ^. 
mH 
ft 
6 
(p 
1) Schoenbein treated some seeds for half an hour with very diluted prussic 
acid and found that most of these seeds did not germinate any more. Some of the 
seeds, however terminated imperfectly (Zeitschrift, f. Biol. 1867, Bd. 3, S. 14c—3). 
