714 
Yeif roisoning. 
cation lias also to be taken into account. Many alkaloids are, 
by suck simple processes as boiling with dilute acids, changed 
into related substances (sometimes alkaloids, sometimes not), 
which of course may have totally different physiological effects. 
Now, in one of the memoirs cited above (Amato and Caparelli), 
we read that an extract containing the alkaloid was boiled for 
some time with dilute sulphuric acid in order to distil off a small 
(Quantity of essential oil smelling like wild fennel ; it is therefore 
possible that Amato and Caparelli’s alkaloid, at any rate, was 
an alteration product of that present in crude yew leaves, and 
not the original one. 
From the foregoing remarks most readers will conclude that 
]\[r. Squarey’s ingenious explanation of the capricious occurrence 
of yew poisoning Avill derive more strength from sufh direct evi- 
dence and opinion as he may have collected from general sources 
than from any chemical reasoning that is available without con- 
siderable further research. The preliminary experiments made 
by Mr. Stuart Wortley under my direction, the publication of 
which in The Times had the useful effect of evoking free venti- 
lation of the subject, and a conflict of evidence from all quarters, 
now appear to me, after further experiments, to afford much 
less support to Mr. Squarey’s theory than we at first supposed. 
In reply to a published query I take this opportunity of stating 
that the leaves we used, then and since, were air-dried at a gentle 
heat, until they crumbled between the fingers, the powder thus 
obtained being passed through a fine sieve. As The Times letter 
shows, we followed the process of Dragendorff, the greatest living 
authority on the extraction of alkaloids from plants, but have since 
found that as regards taxine he is on two highly important points 
(the solubility of the alkaloid in benzine and its non-precipita- 
tion by chloride of gold, which he gives as one of its most 
characteristic [!] reactions) in direct contradiction with Hilger 
and Brande, the latest investigators of this particular alkaloid. 
I have, therefore, thought it desirable to repeat the experiment 
on a larger scale by a modified process. Half a pound each of 
the powdered and sifted air-dried leaves of the male and female 
yew were exhaustively extracted by percolation with hot alcohol. 
fiTiis extraction occupied two days in each case, at the end of 
which time all the green colouring matter of the leaves was 
perfectly extracted, and tlie residue was entirely destitute of 
bitter taste. The alcoholic extracts were purified from the 
large mass of chlorophyll and other substances soluble in alcohol 
by processes unnecessary to detail, aud the crude alkaloidal 
substance finally obtained was submitted to the usual tests, none 
of which unfortunately are characteristic of taxine. From both 
male and female leaves there was obtained a crude alkaloid 
