4 o 
ON THE POISONOUS ACTION OF DI-CYANOGEN. 
Only in one case, where the turnip seeds had remained in the 
hydrocyanic acid solution, the development of the cotyledons 
was observed after 6 days while the life of the root-germ was 
entirely destroyed. Here probably the hydrocyanic acid did not 
enter far enough into the seeds to kill all the cells, while the 
root-germs were more exposed. 
Action of Di-cyanogen and Prussic Acid 
upon Lower Aquatic Animals. 
When under the microscope infusoria, nematodes, rotatoria, 
annelides, Copepodes, and Ostracodes were brought into contact 
with several drops of dicyanogen-solution in a dilution of 
i : 2000, all the life was annihilated within two minutes, while 
in a parallel experiment with an equal dilution of CNH the 
animals were alive after 30 minutes, but some time afterwards 
died under convulsions 1 2 ). In di-cyanogen solution of 1 :10000 
(200 c. c.) the death of these animals very soon took place, also ; 
only the worms lived longer, but after 15 hours they also died. 
In hydrocyanic acid of the same dilution the animals lived 
longer than in the cyanogen solution, and still after 15 hours 
ostracodes showed convulsions in their legs. Even in the dilu¬ 
tion of i : 100000 of dicyanogen all infusoria with the excep¬ 
tion of some monadines were killed. Also the copepodes died, 
but the ostracodes and worms still showed convulsions. In 
hydrocyanic acid of the same dilution many infusoria were 
alive after 5 hours, and some even after 18 hours. In a second 
experiment with some mud rich in infusoria (Paramaecium) 
some individuals were found alive after one hour in cyanogen 
solution of i : 20000, but all were killed after 20 hours even in 
the solution of 1 : 100000, while in the case of hydrocyanic acid 
in the same dilution many infusoria were left alive. 
We see, therefore, that all these experiments prove the di-cy¬ 
anogen to be a stronger poison than hydrocyanic acid; and, 
therefore, the results of B. Bunged with vertebrate animals, that 
1) The assertion of Schaer (Zeit. f. Biol. 1870, Bd 6, S. 511), that infusoria are 
not killed by HCN is certainly erroneous. It may be that only an experiment of 
short duration under the microscope had been made. In our experiments with 
infusoria ordinary well-water was used for the dilutions. 
2) According to B. Bunge (Arch f. exper. Path., Bd. 12, S. 41-75, or, Jahresb. 
f. Anat. & Physiol., 1879, Bd. 8., Ab. 2, S. 187), small doses of cyanogen produce 
general central paralysis. With warm blooded animals dyspnoe, and paralysis of 
respiration are produced. For killing a cat 0.02 grm. cyanogen are necessary while 
of prussic acid 0.004 gnu. suffice. 
