236 



Yew Poisoning. 



There is little doubt that in the numerous recorded instances 

 of fatal effects from eating yew leaves there exists sufficient 

 evidence to show that, under some circumstances, the yew 

 tree contains an active poisonous principle, but the conclusions 

 hitherto obtainable are very indefinite. It is possible, of course, 

 that the poisonous principle does not exist in the leaves, but 

 is the product of the action of the juices of the stomach or of 

 the fermentation during the drying of the leaves. 



Various chemists have been successful in separating from 

 yew leaves an alkaloid substance to which the name taxine 

 has been given ; but the particulars given concerning it by 

 different experimentalists vary considerably, and it was with 

 the object of learning more as to the constitution of this 

 substance that investigations were undertaken at the Govern- 

 ment Laboratory. 



Considerable difficulties were at first encountered in obtaining 

 a sufficient quantity of the alkaloid. By various methods, from 

 O'oy to o*i2 per cent, (calculated on the green leaves) of taxine 

 was obtained in preliminary work from female yew leaves. Sub- 

 sequent treatment of male leaves gave o"i8 per cent. Although 

 this amount is greater than that obtained from the female leaves 

 in the preliminary examination, the inference cannot be drawn 

 that the actual quantity present in the leaves was greater : the 

 substance undergoes change so very easily that the quantities 

 first yielded are thought to be too low. There appeared to be 

 no difference in the quantity yielded by fresh and by air-dried 

 leaves. 



The taxine, after drying in a vacuum, presented the appearance 

 of very fine, glittering particles, extremely light, with no smell 

 and a very bitter taste. 



The physiological action of taxine was examined in 1876 

 in Germany, and it was stated that, when administered to frogs, 

 rabbits, cats, and dogs it depresses the action of the heart and 

 interferes with the respiratory functions, death ensuing from 

 suffocation in a short time. It has been asserted, however, that 

 taxine has no action on guinea-pigs, and further experiments 

 are required to establish definitely whether the alkaloid is 

 actually poisonous, and if so, how it acts, and whether, as 

 alleged, certain animals are immune to it. 



