1895.] Water Current in Cucumber Plant*. 453 



up. — Most of the vessels are full of gelatine. 8 cm. up. — About 

 one-third of the vessels are full. 12 cm. up. — No gelatine in 

 the vessels. Three of the nine bundles show no trace of 

 stain. There is no fluid in the lumen of any of the vessels of 

 the other 6 bundles, but the walls of the vessels and connect- 

 ing tissues are partially stained in 4 bundles, and entirely in 

 2.30 cm. up, i. e., above several nodes.-^The walls of a part of 

 the vessels of each bundle are tinged with the stain, but less 

 strongly than at 12 centimeters. The lignified parts of all of 

 the spiral vessels show the stain, but part of the pitted vessels 

 are free from stain, and all of the phloem, fundamental tissue, 

 collenchyma and sclerenchyma. It would seem as if the 

 spirals brought up the stain (the almost inappreciable quantity 

 which passed by the gelatine plugs), and that from these it 

 diffused out into the rest of the xylem. When the walls of 

 the pitted vessels were stained, those of the connecting tra- 

 cheids were also stained. 50 cm. up. — The red color is restricted 

 to 4 inner and 2 outer bundles. In one of the two outer bundles 

 and in all of the inner ones, the stain is confined to the region 

 of the spirals and is barely visible in these. Longitudinal 

 and oblique cuts also show in a striking way the restriction of 

 the stain to the spirals. 60 cm. up.— Barest trace of stain in 

 3 bundles. 65 cm. up.— Only slightest trace of stain, restricted 

 to the spirals of 2 bundles. 70 cm. up.— No trace of stain. 

 80 cm. up.— No trace of color. Two branches were given off 

 just under the 50 cm. cut : In the lower there was a trace of 

 stain in two bundles at 5 cm. from the main stem ; in the 

 the other there was no trace of the stain, 2 cm. or 5 cm. out. 

 Here there was every opportunity for water to pass through 

 the walls of the vessels, the osmotic pull probably amounting 

 to a pressure of several atmospheres, but there is no conclu- 

 sive evidence that even a single drop passed up in this way. 

 The very slight amount of eosine which passed up the stem 

 may have gone through the walls of the vessels in obedience 

 to the law of surface tension or may have passed through the 

 lumina, owing to the incomplete plugging of some of the ves- 

 sels, those which showed no gelatine being probably plugged 

 by air and inoperative. 



