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 Ph^snogams. 



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 

 1 : 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 1 : 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, Roem.) 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 ). 



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. vSome of the 

 seeds, however ,germinated imperfectly (Z eitschrift. f. Biol. 1867, Bd. 3, S. H2_ 3 ). 



