=Laburnum= (_Cytisus Laburnum_ L.). The well-known and much admired Laburnum must be regarded as one of the most poisonous species of British plants. By numerous experimental researches Cornevin proved that all parts of the plant are poisonous—root, wood, bark, leaves, flowers, and seeds, especially the seeds. In his experiments the horse, ass, sheep, goat, dog, cat, fowl, duck and pigeon, were utilized, seeds being given. He found that 80 centigrammes per kilogramme live weight would be necessary to kill a horse (say 1 lb. for an animal of 1200 lb. live weight), 60 centigrammes per kilogramme live weight to kill an ass (say 6 oz. for an ass weighing 600 lb.); and 6 grammes in the case of a fowl (say 0·4 oz. for a fowl weighing 4½ lb.). The sheep and goat he was not able to kill, as they refused the food after a certain point; the dog and cat he was not able to kill because they so readily vomited; and the duck and pigeon vomited with extreme facility. Many cases of the poisoning of children have occurred through the ingestion of the flowers and seeds. In 1908 a case was recorded by the Board of Agriculture and Fisheries, in which two horses were alleged to have been poisoned in North Wales by laburnum seeds, a very small quantity of which was found in their stomachs after death. Müller states that in Dalmatia goats which had eaten _Cytisus Weldeni_, though themselves uninjured, produced milk which was poisonous to man. _Toxic Principle._ All parts contain the toxic alkaloid _Cytisine_ (C_{11}H_{14}N_{2}O), said by Moer and Partheil to be identical with Ulexine; it is found in the seeds to the extent of 1·5 per cent. Cornevin states that the root, wood and bark are nearly constant in toxicity, but that the leaves and pods present remarkable seasonal variations owing to the migration of the poison into the seeds. The toxic property is not destroyed by drying of the plant. _Symptoms._ Laburnum poisoning is of the acrid, narcotic type, with, in man, nervous symptoms, abdominal pain, vomiting, purging, tetanic spasms and convulsions.