the T r (inspiration- Current . 40 7 
downwards by lowering the water-bath to allow of the 
contraction of the paraffin being made good by supply from 
below. When all was cold, the end was pared to expose 
lumina free from paraffin. The stick now drew up water 
freely, 3 or 4 cc. in 15 minutes, but let up no air, nor would 
it suffer mercury to pass up. The water pumped through 
was next tested by a solution of tannin, but remained per- 
fectly clear. We conclude therefore that no direct air- 
passages remain open, and that the wood of the Yew itself 
will give no obscuring reaction with tannin. 
Some gelatine which had been cut up into fine threads and 
soaked in repeatedly changed water for two days was now 
melted and made very dilute, so that it set weakly at 13 0 . 
At a temperature of 30° to 40° this was supplied to the lower 
end of the Yew, the latter as before being kept warm through- 
out its entire length by a water-jacket which was never raised 
above 40°. At the expiration of four hours the liquid within the 
vacuous tube had risen by about 5 cc. The experiment was 
then stopped, and the contents of the tube tested with tannin. 
There was an opalescent precipitate. Comparison with the 
solution below showed that much of the gelatine had been 
held back by the wood. 
Starting the experiment a second time with the same piece 
of Yew it transmitted 3-5 cc. in four hours ; the liquid 
drawn up affording this time a much denser precipitate. 
A final test showed the wood to be still impervious to air 
when a vacuum was maintained in the tube. 
A similar experiment with the wood of Pinus austriaca 
gave a like result. It was observable that if the dilute gelatine 
was not raised some few degrees above its melting-point — 
i. e. till the solution almost ceases to be opalescent — its 
passage was much less marked ; indeed in some experiments 
only traces were transmitted through the wood. This appears 
to be due to the fact that in solutions presenting an opalescent 
or milky appearance the gelatine is probably still in the solid 
or gelatinous state ; the heterogeneous distribution and differ- 
ence of refractive index giving rise to the milky colour. In 
