v] Conifer se 75 
Toxic Principle. The researches of Marme pointed to the alkaloid 
Taxine (C^H^NO^) as the toxic substance. Later investigations of 
Thorpe and Stubbs confirmed this view, and it is generally agreed that 
this substance is the toxic principle, though doubts as to its being the 
only poison have been expressed. Taxine has a bitter taste, is a heart 
depressant, and may cause death from suffocation. The yew also 
contains a considerable quantity of Formic Acid, and the acrid, 
irritant volatile Oil of Yew. 
Thorpe and Stubbs (Trans. Chem. Soc., 1902) found in the fresh 
leaves of the common Yew from 0-1 to 0-18 per cent, of Taxine. In an 
investigation of the Irish Yew ( T. baccata var. fastigiata) Moss found 
Taxine present as follows : 
Leaves from female tree, fresh . . . . 0-596 per cent. 
,. .. .. 0-623 
Seeds from fruit of same tree . . . . . . 0-079 ,, 
Another female tree leaves . . . . . . 0-323 
seeds 0-082 
In the leaves of the male common Yew Moss found 0-082 per cent, 
of Taxine, or less than one-half the quantity found by Thorpe and 
Stubbs. 
Symptoms. The Yew is irritant and narcotic, and the poison is 
not cumulative, but on the other hand rapidly effective, so that animals 
may die apparently suddenly, no previous symptoms having been 
observed. 
When small quantities only have been taken the closest attention 
is necessary to discern the symptoms, which simply consist in a little 
excitement with a slight rise in temperature. 
With larger (but not fatal) quantities the first symptom, excitement, 
is more pronounced and is followed by nausea, and (where possible) 
vomiting. There is a pronounced slackening of respiration and circula- 
tion, the pulse being small, slow, and difficult to perceive, and the 
movement of the flanks very slow; sensibility is diminished. There 
is a fall in temperature, the skin and extremities being cold. The head 
is lowered, the eyes are closed and there is decubitus. In some cases 
pregnant animals have aborted. In the horse there are muscular tremors 
and frequent urination. In cattle and sheep rumination is suspended 
and there is more or less pronounced tympanites, with eructation, 
nausea, and sometimes vomiting. Pigs bury the head in the litter and 
sleep, their sleep being interrupted from time to time by nausea and 
groaning; or the animals rise, stagger about, and lie down again. 
