408 Dixon and Joly. — The Path of 
all cases a considerable quantity of the gelatine is held back. 
One quantitative experiment on Taxus gave the percentage 
of gelatine in the transmitted liquid as only half that in the 
original solution. 
In one experiment we stained the gelatine with Klein- 
enberg’s haematoxylin. The gelatine was made of such 
strength as to set at about 20°, and was supplied at 40° to the 
wood of Taxus baccata. It passed out colourless into the 
glass tube, about 1 cc. in two hours, the length of the wood 
traversed being 2*5 cm., and its cross-section 2-2 sqr. cm. 
This wood had not been treated with paraffin, as it revealed 
no direct air-passages upon trial. As the haematoxylin does 
not stain wood, this experiment points to a mechanical sepa- 
ration from the gelatine owing to the passage of the latter 
through membranes or walls. It is possible, however, that 
some of the stain was taken up by the cellulose walls of the 
medullary rays and the tori of the pit-membranes. 
Microscopical examination of branches choked with gelatine 
mixed with Indian ink, after the manner of Errera and Stras- 
burger, showed that the closing membranes of the pit had 
exerted a straining action, accumulating Indian ink upon the 
one side, so that the pits were very sharply picked out as 
black objects. This straining action is suggestive of the 
passage of the medium carrying the precipitate ; and although, 
so far as this observation is concerned, there might have been 
straining of the gelatine from the water in which it was 
dissolved, still taken in conjunction with the other observa- 
tions, we think it supports the view led to by those obser- 
vations, i. e. that dilute melted gelatine can pass through the 
substance of the closing membranes, and if so is very probably 
capable of penetrating into the cell-wall, or otherwise we 
must suppose perforations to exist in the pit-membrane or 
its torus. 
We decided to try the effect of using paraffin wax of low 
melting-point as the material for choking the lumina, com- 
paring the effects with those of gelatine. Four similar 
branches of Lime, Tilia europaea , were cut (May 9) as far as 
