UMBELLIFERÆ.
Cowbane or Water Hemlock (Cicuta virosa L.). This plant is undoubtedly exceedingly poisonous, and fatal cases have occurred in both man and farm live stock. It has been mistaken by man for parsley, celery or parsnip, with fatal results, many persons having succumbed to it. The rootstock is attractive to children on account of its sweetish taste. Pott says that either fresh or dry it is poisonous to all animals when only a small quantity is eaten, and often causes rapid death. Sheep and goats appear to be less readily affected than other domestic animals, and cattle to be most sensitive. The loss of eleven animals in Brittany was noted in the Veterinarian in 1877, and a number of cattle died in Ireland (Veterinary News, 1911), death in both cases being due to Cowbane. It is clearly dangerous to grazing animals which have easy access to it, especially if ordinary herbage is scarce. Hedrick (Canada) is quoted as stating that a piece of the root about the size of a walnut is sufficient to kill a cow in about fifteen minutes; and Müller says that the quantity of dried plant sufficient to kill a horse appears to be about 1 lb. According to Kanngiesser the mortality in human poisoning due to this plant amounts to 45 per cent. of the cases.
Toxic Principle. The poisonous character of Cowbane has not been fully investigated, and the toxic principles are given as the alkaloid Cicutine, with Oil of Cicuta, and Cicutoxine. The last is a bitter resinous substance classed by Cushny in the picrotoxin group; it occurs in the dry root to the extent of 3·5 per cent. The toxicity is stated to vary with season and climate; the rootstock is most poisonous in spring.
Symptoms. In man the yellow poisonous juice in the rhizome induces epileptic convulsions, followed by death. The cicutoxine gives acrid narcotic symptoms quickly followed by fatal results. The symptoms usually appear within two hours, and death ensues in half-an-hour to several hours. The symptoms which appear in an hour or so are given as loss of appetite, salivation, vomiting (in swine), nausea, colic (in horse), bloating (in cattle), diarrhœa, irregular pulse and heart, dilatation of pupils, rolling of eyeballs, vertigo, reeling in circles, twisting of neck, falling down, automatic movement of limbs, opening and shutting of mouth, and death, usually with convulsions, in from half an hour to an hour after first manifestation of symptoms.
For cattle, Lander gives hurried respiration, collection of froth at the mouth and nostrils, and tympanites. The limbs are extended and alternately stiffened and relaxed.
In his description of the symptoms Esser states that swallowing is difficult, the tongue is stiffened, there is salivation, and death takes place after loss of consciousness and convulsions.
REFERENCES.
[31], [73], [81], [123], [141], [151], [170], [190], [203], [205], [213], [233], [238].
Water Parsnip (Sium latifolium L.). The leaves and especially the root of this species are regarded as poisonous, and the plant is described as “poisonous” by Strasburger.
According to Müller the symptoms resemble those produced by Chaerophyllum (p. [40]). After eating the roots cows showed symptoms of excitement, leading, in some instances, very quickly to death. The milk, according to Cornevin, is of a disagreeable flavour.
The related S. angustifolium has also been mentioned as objectionable. As regards the toxic principle these plants have not been closely studied, and it is not possible to give detailed symptoms.
REFERENCES.
Water Dropwort (Oenanthe crocata L.). This weed of marshes, ditches, and similar wet spots, has been a frequent cause of loss of stock. Cases of fatal human poisoning have also occurred, owing to the leaves having been mistaken for celery and the rootstock for parsnips. Several cases of the poisoning of cattle have been recorded in the veterinary journals, and sheep and cattle died on a farm near Bristol (Jour. Roy. Agric. Soc., 1898). Horses have also been poisoned. Johnson and Sowerby (1861) record the poisoning of 17 convicts near Woolwich, the leaves and roots being eaten in mistake for celery and parsnips respectively. Nine suffered from convulsions and became insensible; one died in five minutes, a second in a quarter of an hour, a third in an hour, and a fourth a few minutes later, while two more died during the next few days.
Cornevin says that this plant causes the poisoning of animals every year—they eat it willingly, showing an enfeebled instinct owing to domestication. The plant is poisonous in all its parts, the root being the most toxic, and drying does not destroy the toxic property. Cornevin gives the following quantities of the fresh root as necessary to poison various animals:—
| Horse | 0·100 | per cent. of the live weight. |
| Ox | 0·125 | „ „ „ |
| Sheep | 0·200 | „ „ „ |
| Pig | 0·150 | „ „ „ |
| Rabbit | 2·000 | „ „ „ |
Holmes described Oenanthe crocata as the most dangerous and virulently poisonous of all our native plants (Pharm. Jour., 1902).
Other species of Oenanthe are also poisonous in a less degree—e.g. O. fistulosa L., and O. Phellandrium Lamk.
Toxic Principle. Poehl (1895) obtained from the root of this species an amorphous neutral product which he designated Oenanthotoxin. The latest investigation is that by Tutin, who examined entire dried plants collected in early spring, and the experiments confirmed the conclusion arrived at by Poehl, that the toxic principle is a neutral resin. A dark-coloured, viscid resin, insoluble in water, and equal to 3 per cent. of the weight of the plant, was extracted, and it is stated that the neutral portions of the petroleum and ether extracts of this resin represent the toxic principle of the plant. As there is no evidence of the homogeneity of this product, and it is probably complex in character, it was given no name or formula. The fact that it has poisonous properties was ascertained by administering the various products to guinea pigs per os.
Symptoms. In poisoning by O. crocata the symptoms generally appear very quickly, and in serious cases death may follow in from one hour to a few hours. In Tutin’s experiments on guinea pigs the extracts referred to above rendered the animal hypersensitive in two to four hours, while marked convulsions, with trismus soon appeared; the heart-beat became very noticeably slow and the convulsions persisted until death ensued. There is great restlessness, difficult breathing, convulsions, loss of sensation, blindness and stupefaction (Müller); Lander says the symptoms recall hemlock poisoning, with the addition of green fœtid diarrhœa.
In cattle, one hour after eating, there is depression and accelerated respiration; the conjunctivæ are injected, the eye turns in its orbit, the pulse is weak but rapid, and there is foaming. Later, there is colic, and spasmodic contractions of limbs and jaws. If the quantity ingested is sufficient to cause death, the animal falls, but still moves its limbs. There is bellowing, contraction of pupils, insensibility, and death in convulsions—or, if not fatal, cattle may remain paralysed.
In the horse, the appearance of the symptoms and the course of the illness are much more rapid and the nervous symptoms are accentuated.
If the pig has consumed only a small quantity it soon gets rid of the poison by vomiting; but if the quantity is considerable there is no vomiting and death is as rapid as with cyanide poisoning (Cornevin).
REFERENCES.
[10], [14], [73], [81], [141], [146], [170], [190], [205], [209], [213], [235], [246].
Fool’s Parsley (Aethusa Cynapium, L.). Much has been written about the toxic properties of this weed of cultivated fields, principally because, owing to the fact that the foliage has often been mistaken or misused for parsley and the roots for radishes (!), it has been the cause of human poisoning, though it seems to be one of the least active of the poisonous Umbellifers. Its poisonous character is undoubted, but it is unlikely to cause the poisoning of stock, which seem to refuse it. Some authors regard it as strongly poisonous, but others as more or less harmless. Johnson and Sowerby cite a case in which a child of five years old died within an hour after eating the root, and a second death (in Germany) within twenty-four hours from the use of the leaves in soup.
The most complete account of this plant is that by Power and Tutin, issued from the Wellcome Chemical Research Laboratories in 1905. Many authors since 1807 are cited as writing of its poisonous properties, and of cases of poisoning, two of which terminated fatally. Miller (1807) says that “most cattle eat it, but it is said to be noxious to geese.” Bentley and Trimen write that “in all recorded experiments with it on animals, it has had poisonous effects.” Dr. John Harley (1876 and 1880), after experiments on a child and adults, concluded that the plant was absolutely free from the noxious properties attributed to it. In 1904, however, a case of severe poisoning by it was recorded (Brit. Med. Jour., July 16, 1904, p. 124).
Toxic Principle. This has for many years been stated to be the alkaloid Cynapine. For their investigation Messrs. Power and Tutin collected the plant round London in July and August, with the fruits still green, and after thorough chemical examination found 0·015 per cent. of an essential oil of rather unpleasant odour; 0·8 per cent. of resinous substances; and an exceedingly small amount of a volatile alkaloid having the peculiar characteristic odour of Coniine. The amount of hydrochloride of the alkaloid obtained showed that if the base were Coniine it would correspond to only 0·00023 per cent. of Coniine in the plant. In a degree this confirms the statement by Walz (1859) that the fruit “contains a volatile base, very similar in odour and chemical behaviour to Coniine, and probably identical with it.” The investigators suggest that the alkaloid is Coniine, and the small amount would justify the opinion, but there may be variation in toxic property according to stage of development and climate. The authors conclude that “it cannot be considered improbable that under favourable conditions of growth, the proportion of alkaloid may be increased to such an extent as to impart to the plant the poisonous properties ascribed to it.”
Symptoms. In a child which died, there were abdominal pain, a feeling of sickness, and a tendency to lockjaw, and death supervened within an hour; and in a German case, vomiting, diarrhœa, lockjaw, and death in 24 hours. (Johnson and Sowerby.) The plant causes convulsions and stupor, with nausea and vomiting (Henslow).
The symptoms observed in cows are loss of appetite, salivation, fever, uncertain gait, and paralysis of hind limbs (Müller).
Pott refers to a case which occurred in Guernsey among horses. Animals with white muzzles and feet had diarrhœa, while other horses remained healthy. All white places on the body were badly inflamed. Pammel states that the plant causes stupor, paralysis and convulsions in domestic animals.
REFERENCES.
[45], [73], [81], [121], [130], [141], [190], [203], [213], [214].
Chervils (Chaerophyllum sp.). No investigation of these plants appears to have been undertaken, but C. sylvestre L., though eaten by some animals, including the ass and the rabbit, is stated by a German observer (vide Cornevin) to have caused the death of pigs. Müller states that according to the literature both cows and pigs have been poisoned, even fatally, by C. temulum L. The plants have a strong odour and acrid taste.
Toxic Principle. This, if any, appears to be unknown, though Müller (1897) says that C. temulum contains in all its parts the little known Chaerophyllin (? alk.).
Symptoms. The pigs referred to above as having died were said to show paralysis, dilated pupils, and enteritis, and to refuse food. Postmortem examination showed acute gastro-intestinal inflammation. In the case of cows there are similar symptoms.
REFERENCES.
Hemlock (Conium maculatum L.). This plant, famous from ancient times as extremely poisonous, has a fœtid, disagreeable odour—a mousy smell—especially noticeable when the plant is bruised. It has caused human poisoning in three ways: the seeds have been eaten in error for anise, the leaves for parsley, and the roots for parsnips.
Animals rarely appear to eat this plant, but cases have been recorded. It is stated that in the United States many domestic animals have been killed by it; and Ewart says that it is responsible for poisoning a number of cows in Victoria. Goats are believed to be largely immune to the poison, or are less harmed than other animals, and sheep are stated to eat the plant with impunity, though cases of poisoning are recorded. Johnson and Sowerby state that horses have occasionally swallowed considerable quantities without apparent effect, while Cornevin remarks that to cause death a horse would need to eat 4 to 5½ lb. of the fresh plant, or a cow 8¾ to 11 lb.
Hemlock is probably most dangerous to live stock in the spring, when green herbage is least plentiful and the young shoots of hemlock are fresh and short. Chesnut says that the root is nearly harmless in March, April and May, but dangerous later, especially in the first year of growth; but Esser states that it is only poisonous in the spring. The foliage is more poisonous before flowering than after, when the poisonous principle passes to the fruits, which are more poisonous before ripening (three quarters ripe) than afterwards. Pott remarks that after eating hemlock cows give milk with a bad taste.
Toxic Principle. Early in summer the toxic principle appears to be chiefly contained in the foliage, but later in the fruit, particularly when still green. Among the substances contained in hemlock are the toxic alkaloid Coniine (C8H17N), the poisonous Coniceine (C8H15N), Conhydrine (C8H17NO), the alkaloid Methylconiine (C9H19N), Pseudoconhydrine (C8H17ON). Coniine may be described as an oily, colourless, quite volatile liquid, quickly turning brown on exposure to the air, and giving a mousy odour to the whole plant. The amount of Coniine in the fresh leaves is given (Pammel) as 0·095 per cent., but in the ripe seeds 0·7 per cent. English fruits contain much more of the total alkaloids than imported fruits. Owing to the volatile character of the poisons hemlock largely loses its toxicity when dried in hay, and is therefore the less likely to prove injurious to domestic animals.
Symptoms. Hemlock is a dangerous narcotic plant. Even the smallest quantities may cause inflammation of the digestive organs, paralysis and death. The general symptoms are salivation, bloating, dilatation of pupils, rolling of eyes; laboured respiration, diminished frequency of breathing, irregular heart action; loss of sensation, convulsions, uncertain gait, falling, and at the end complete paralysis. Death occurs after a few hours. The poison acts on the motor nerve endings, causing paralysis, dyspnœa resulting from paralysis of the pectoral nerves, and acceleration of the heart from that of the inhibitory fibres of the pneumogastric.
Small quantities cause in the horse a little prostration, yawning, acceleration of pulse, dilatation of pupils and sometimes muscular spasms of the neck and shoulders. Large quantities cause nausea, unsuccessful attempts to vomit, gritting of teeth, accelerated respiration and dyspnœa, and muscular tremors commencing in posterior members and spreading to anterior members and spine. There is next difficulty of locomotion, sweating (but not continual), falling, paraplegia, then paralysis, loss of feeling, lowering of temperature, rapid pulse, increasingly difficult respiration, and death from stoppage of respiration.
With cattle there is ptyalism, cessation of digestion, bloating, constipation, weakness and stupor. Pregnant cows have been observed to abort; the milk of cows has an unpleasant flavour. There are bloody evacuations in some instances in the case of the ox. In cows Chesnut says that there was “loss of appetite, salivation, bloating, much bodily pain, loss of muscular power, and rapid, feeble pulse.”
In sheep the abdomen is tucked up, the animal has a dazed appearance, there is dilatation of pupils, unsteady gait, the hind limbs being dragged, coldness, and death after a few convulsive movements.
In the pig there is prostration and inability to move, coldness, slow breathing, livid mucous membranes, imperceptible pulse, paralysis, particularly of the posterior members, and no convulsions.
REFERENCES.
[4], [16], [52], [53], [73], [81], [82], [91], [128], [141], [161], [203], [205], [213], [238].
CHAPTER IV
ARALIACEÆ.
Ivy (Hedera Helix L.). The berries of the Ivy are said to be largely eaten by certain birds (e.g. blackbirds, thrushes, wood-pigeons), but have poisoned children. The plant has long been said to be poisonous, but no definite case of poisoning of live stock has been discovered; possibly farm live stock would need to eat a considerable quantity for serious effects to be induced. Indeed, when keep is short, it is quite common in some districts to see Ivy strewed on the fields for cattle and sheep to eat, and it is very frequently given to sick animals by country people (Garnett).
Toxic Principle. This has not been closely studied, but ivy contains a bitter principle which is strongly cathartic, emetic and purgative. Ivy contains a poisonous glucoside Hederin (C64H104O19) and a resin (Gummi hederæ).
Symptoms. As suggested above, it is doubtful whether animals have been poisoned by Ivy. Symptoms given appear to refer to children, and consist in sickness, diarrhœa, nervous symptoms, excitement at first, then convulsions and paralysis (Müller). Sickness and purgation (Esser).
Cornevin states that the symptoms are complex, emeto-purgative effects being present, with nervous symptoms resembling those of intoxication, viz. excitement, then coma, convulsions, uncertain gait, and stertorous respiration.
REFERENCES.