518 MANUAL OF POISONOUS PLANTS 



almond. Externally, hydrocyanic acid produces a paralytic effect. When taken 

 internally, it acts as a sedative upon the mucous membrane. Prof. Winslow 

 gives the following characteristics of poisoning: 



In poisoning, the blood becomes first a bright arterial hue, and later assumes a dark, 

 venous color. The first condition is due to the fact that the blood does not give up its 

 oxygen for some reason. Brunton suggests that it is because the blood is hurried so rapidly 

 through the dilated peripheral vessels that it does not have time to yield up its oxygen. 

 The dark color of the blood is probably owing to asphyxia and accumulation of carbonic 

 dioxide, following the paralytic action of prussic acid upon the respiratory centre. 



Prussic acid has an essentially depressing action upon the nervous system as a whole. 

 The brain, cord and nerves become paralyzed by large doses. 



The spinal cord is paralyzed at a period after coma and convulsions have appeared. 

 The peripheral nerves and muscles are paralyzed directly by toxic doses, and not through 

 the mediation of the central nervous apparatus. 



Inhalation of the pure acid will cause death in a confined atmosphere, and even in- 

 halation of the medicinal solution will induce the physiological symptoms of the drug. 



He also says of the toxicology of prussic acid: 



Prussic acid is one of the most powerful poisons in existence. Death may be in- 

 stantaneous, or life may be prolonged for over an hour after lethal dose. More commonly 

 the animal survives for a few minutes, and we observe the following symptoms in dogs: 

 The animal falls, froths at the mouth, the respiration is of a gasping character and occurs 

 at infrequent intervals. There is unconsciousness, the pupils become dilated, there are 

 muscular tremblings, and clonic or tonic spasms. Defecation and micturition occur, and 

 erections often ensue in the male. Respiration ceases before the cardiac pulsations. 



Three stages may be distinguished in fatal poisoning. First: a very short period 

 elapses before the symptoms appear. There are giddiness, difficult breathing, and slow 

 pulse in this stage. Second: the pupils dilate, vomiting may occur, and the animal utters 

 loud cries. Spasmodic defecation, micturition and erections may be present, with con- 

 vulsions and unconsciousness. Third: the last stage is characterized by collapse, spasms, 

 general paralysis and death. The subacute form of poisoning may ensue and prove fatal, 

 or, owing to the volatile character of the drug, complete recovery may take place within 

 one-half or three-quarters of an hour. Occasionally dogs continue to be paralyzed for several 

 days and get well. The minimum fatal dose recorded in man is 9/10 of a grain of pure 

 acid, or about 50 drops of the medicinal solution. Four to five drachms of the diluted 

 acid frequently, but not invariably, cause subacute poisoning and death, in horses, within 

 an hour. One to two drachms of the pharmacopoeia! preparation usually kill dogs within 

 ten minutes. 



Prussic acid is commonly used to destroy the domestic animals. Two to four drachms 

 of the medicinal acid are to be given to dogs and cats of the ordinary size, and certain, 

 painless, and rapid death will occur if a fresh preparation of the drug can be obtained. 

 The unopened, half-ounce vial, kept by druggists, is recommended. Big dogs, horses, and 

 the other larger animals are not killed rapidly, nor sometimes at all, by great quantities 

 of the diluted acid. Hence, shooting is a more humane and preferable mode of death for them. 

 In the experience of the writer, one to two drachms of prussic acid saturated with potassium 

 cyanide, failed to kill a horse, when injected directly into the jugular vein. The odor 

 of the acid lingers about the animal for a few hours after death; the eyes are fixed and 

 staring; the pupils dilated; the teeth are clinched tight and covered with froth, while the 

 blood is of a very dark color. The treatment embraces emptying the stomach by large 

 doses of promptly acting emetics, or by the stomach tube, or pump; atropin, ether, and 

 brandy subcutaneously, and inhalations of ammonia, together with artificial respiration, 

 and hot and cold douches upon the chest. 



Hydrocyanic acid is produced by a number of other plants referred to in 

 another connection. 



Wild cherry bark (Prunus serotina} and leaves by distillation yield a vola- 

 tile oil resembling that of bitter almond. The same is true of the P. virginiana. 

 Hydrocyanic acid is formed only by the action of a ferment upon amygdalin 

 which is present in all plants of this sub-order. Fresh leaves are generally 

 considered harmless, but Chesnut says that cattle are frequently poisoned from 



