924 EXPERIMENT STATION RECORD. 



showed that the leaves of the wild plum, as well as those of the culti- 

 vated varieties, seemed to be harmless. The least poisonous of the 3 

 principal species is the wild red cherry (Prunm pennsylvanica). The 

 second species (P. virqiniana) is more common than the former and is 

 also more poisonous; but by far the most dangerous variety occurring 

 in New England is the wild black cherry (P. serotina). 



The authors state that "the poisonous property of all species of cherry leaves is 

 due to hydrocyanic acid, popularly known as prussic acid. This compound does not 

 exist as such in the growing leaf, hut is derived from a class of substances called 

 glucositls, of which amygdalin is the type peculiar to the cherry. This, or a closely 

 allied body, is to be found not only in the leaves and bark, but especially in the 

 stones of cherries, peaches and plums, and the seeds of the apple. By the action of 

 moisture, and a vegetable ferment called emulsiu which exists in the plant, a complex 

 chemical reaction takes place that begins in the leaf the moment connection with 

 the circulatory system is cut oft". The 3 products of this reaction are hydrocyanic 

 acid, grape sugar, and benzaldehyde or hitter-almond oil." 



The popular opinion that the leaves of the wild cherry are poisonous 

 only "when in a wilted condition is proved to be erroneous, since analyses 

 showed that freshly cut leaves yield nearly as much acid as the wilted 

 leaves when calculated to the fresh material taken. On the the other 

 hand thoroughly dried leaves yield a small amount of acid and as ordi- 

 narily dried, in the hay field, they might be capable of generating a 

 considerable quantity of poison. A tabulation is given in which the 

 analyses of the different species is shown.. The average of 11 analyses 

 of 100 gm. of wild cherry leaves gave 212 mg. of prussic acid. When 

 wilted the amount was found to vary somewhat with the degree of wilt- 

 ing, varying from 244 to 294 mg. per hundred grams of weight after 

 drying. Leaves dried to 42 per cent of their original weight contained 

 71 mg. of prussic acid to 100 gm. of leaves. 



Marked differences were noticed between the quantity of acid obtained 

 from the leaves wilted in bright sunlight and those wilted in darkness, 

 the former producing the larger amount. The condition and stage of 

 growth of the leaves has a marked iufluence on the amount of hydro- 

 cyanic acid occurring in them. The larger, tenderer, and more suc- 

 culent the leaves the greater the amount of acid which can be 

 developed from them. Young shoots which come up where they have 

 been frequently mowed off are much the richest in poison, while the 

 woody leaves from full-grown shrubs or trees contain so little acid as 

 to render them nearly harmless. Ten analyses of the leaves of the 

 wild black cherry from isolated shoots contained 212 mg. per hundred 

 grams of freshly cut leaves, while similar leaves from full-grown trees 

 contained only 100 mg. 



The symptoms of poisoning and the toxic dose of prussic acid are 

 given. The following are the authors' conclusions: 



"The leaves of the wild black cherry are the most poisonous of the 3 species 

 investigated, though all are dangerous. 



" Both the wilted and fresh leaves are poisonous, while the dried are to be regarded 

 with suspicion. 



