POISONOUS PLANTS 203 



The Indian pea was first brought into Europe with 

 cereals of Eastern origin ; but peas of these varieties have 

 long been known to be poisonous, having been mentioned 

 by Hippocrates and Pliny. 



Cases of poisoning amongst horses appear to have been 

 first noticed in England in the eighties. 



In the earlier stages of growth the plant is harmless, and 

 may be used as forage, but from the time of the formation 

 of seed and onward it becomes toxic, the seeds being the 

 most dangerous part. The poison is not lost by drying, 

 nor by boiling for a short time, though possibly prolonged 

 boiling might destroy it. "When boiled the poison seems 

 to pass into the water. Cornevin extracted 5 litres of 

 peas, concentrated the water, and injected the extract 

 into a dog of average weight, which died in twenty-four 

 hours. 



Pathological changes are more speedily produced when 

 meal rather than the whole pea is fed. 

 . Symptoms. — The effects of Lathyrus are very charac- 

 teristic, and the condition known as ' lathyrism ' has been 

 observed in man and all the domesticated animals. 

 Lathyrism is only produced when considerable proportions 

 of the pea enter into the rations, and over a prolonged 

 period of time ; in man generally in the fourth month ; in 

 the horse fed exclusively on the pea, the tenth day ; but 

 when 1 or 2 quarts are given daily only towards about 

 the eightieth day. Moreover, the malady may declare itself 

 so long as fifty days after the cessation of the pea feeding. 



In man a constant sign is paralysis of the lower extrem- 

 ities ; speech, intelligence, and power over the upper ex- 

 tremities are preserved. The symptoms resemble those of 

 dorsal tabes, and lathyrism has further been compared 

 with beri-beri. 



The first complete observations on the horse were made 

 in this country by McCall in 1886.'' An animal was 

 feeding well, but thick in his wind. After going about 

 200 yards with an empty lorry it stood with the forelegs 

 forward, neck stretched, elbows out, and laboured breathing. 



