830 STATE POMOLOaiCAL SOCIETY. 



detached roots, and the roots again covered with the earth in which they grew. 

 The tubes were now fastened in a vertical position to stakes set near the ends 

 of the detached roots, which were one inch m diameter. They were then 

 filled with water to a certain jioint, which was carefully marked, and the 

 changes occurring noted every day. Sometimes the water in a tube would 

 sink away, showing an absorption of the fluid by the roots ; and, again, it would 

 rise and flow over the top of the tube, demonstrating the fact that the absorb- 

 ing power of the root was, sometimes at least, in excess of the affinity of the- 

 cellulose of the wood for water. It was well established that the wood of the 

 roots of trees is in a condition in early spring to absorb with avidity the water 

 from the tubes, while later in the season many of them exude water freely, so 

 as to cause the tubes to overflow. The amount of absorption was recorded in 

 inches, the minus sign being prefixed to the numbers, while the exudation was 

 measured in a sirLilar way, with the omission of the sign. Thirty-six inches 

 of water in one of these tubes weighed one ounce, and from these data it was 

 easy to learn the actual amount of water which was taken up or thrown off 

 daily by esch species. 



ONE OF THE MOST REMARKABLE DISCOVERIES 



in this connection, is the entirely unexpected fact that the roots of the sugar 

 maple do not exude any sap from their wood when protected from frost, and 

 show less independent power of absorbing water from the soil than almost any 

 other species. Hence, there was no flow from the root into the tube at any 

 time, but a constant moderate absorption of water from it. 



THE FLOW 



from the root into the tube is similar to that observed in the tube of an ordi- 

 nary osmometer; but this does not prove that osmose has any influence in this 

 matter, and the doubt about it is not diminished when we see the water mov- 

 ing, sometimes in one direction and sometimes in another. In the sugar 

 maple, the flow was always out of the tube into the wood of the root; in the 

 white oak, the absorption from the tube was, in some cases, as much as one 

 ounce in thirty minutes, but rarely the current was reversed and absorption 

 occurred from the ground ; while, in the elm, the absorption from the tube was 

 at its maximum April fifteenth, and then gradually diminished until April 

 twenty-first, from which date the flow into the tube continued till June 

 thirtieth, when the observations were suspended. 



•A SECTION 



of a white oak root, eight inches long and one incli in diameter, which was 

 freshly dug from the damp earth, April eleventh, and weighed, was then 

 placed with one end in water three-eighths of an inch in deiith, and in ten 

 hours absorbed 3.19 per cent of its weight. This shows that the tissues were 

 far from saturated, and were in an excellent condition to facilitate ordinary 

 root absorption. A mercurial gauge attached to a root of white oak showed 

 on the twelfth of April a suction sufficient to sustain a column of water 10.20 

 feet in height, which was caused by the absorption of the wat<?r in the con- 

 necting tube between the gauge and the root. 



THE MERCURIAL GAUGE, 



which was used for determining the variations of the pressure exerted by the 

 sap of such species as are noted for the abundance of their flow, consisted of a 



