Notes . 
443 
through the wood. To retard the flow the distal end was imbedded in a mass of 
vaseline, and in all cases it was seen that where the vessels contained large air- 
bubbles the front end of each film became more convex when pressure was applied, 
while the hinder end became flattened or concave. These effects become extremely 
pronounced when the bubble is passing the constrictions where segment cells join 
Fig. 8. Diagrammatic longitudinal section of a segment of a vessel. The ends of the segments 
at a a, b b, form the adhesion points of the surface tension films. Fig. 9. View from beneath of 
a surface tension film on the under side of an air-bubble at the middle of a segment, showing that 
water may still be able to pass the air-bubble in spite of the adhesion of the surface tension film to 
the inner wall of the vessel. Fig. 10 . As in Fig. 8, but with less water, so that the films adhere to 
the inner wall, and as in the true Jamin’s chain there is no internal lining of water between the 
water-columns. 
(Fig. 8, a a, bb). The same differences were maintained as the bubble was driven 
slowly along the tube, so that it can be safely assumed that the differences of 
curvature were even more pronounced with velocities too high to permit of direct 
observation. At the same time the coloured solution appeared in front of the last 
few air-bubbles in the series l , so that here we have what appears to be definite proof 
11 These observations can be made on the stem of the Wistaria with the aid of a hand lens 
without injuring the wood. 
H h 2 
