232 PROP. ATTFIEID — PHYSICS A]!fD CHEMISTRY 



draw from the ground about 4 litres or seven- eighths of a gallon of 

 fluid every twenty-four hours. That at all events was the amount 

 flowing from this open tap in its water-system. Even the topmost 

 branches of the tree did not become during the three weeks abnor- 

 mally flaccid, so that presumably no drainage from the upper portion 

 of the tree had been taking place. Besides, after due calculations, 

 I find that the amount of fluid which would exude in the three 

 weeks would be greater than could be contained in the whole of 

 the trunk and branches above the wound even if they were hollow. 

 For three weeks, therefore, the tree had been drawing, pumping, 

 sucking — I know not what word to use — nearly a gallon of food 

 daily from the soil in the neighbourhood of its roots. This soil 

 had only an ordinary degree of dampness. It was not wet, still 

 less was there any actually fluid water to be seen. Indeed, usually 

 all the adjacent soil is of a dry kind, for we are on the plateau of a 

 hill about 270 feet above the sea ; the level of the local water-reser- 

 voir into which our wells dip is about 80 feet below the surface, 

 and the subsoil is very porous ; so that, altogether, the welcome 

 rains sink away from our garden-earth rather rapidly. The total 

 rainfall from the 19th of March to the end of the mouth was, our 

 Secretaiy tells me, eight-tenths of an inch, a little over eighty tons 

 per acre. No rain had fallen in April, when, on the 9th, my 

 gardener, with some difficulty, so closed the wound as to stop the 

 outflow. During the earlier part of the time we had frosts at 

 night, and sunshine but with extremely cold winds during the days. 

 At one time the exuding sap gave, I am told by two different ob- 

 servers, icicles a foot long. A much warmer, almost summer, 

 temperature prevailed afterwards, and no wind. On the 4th of April 

 the temperature of the sap as it escaped was constant at 52° F., 

 while that of the surrounding air was varying considerably.* 



The collected sap was a clear, bright, water-like fluid. After a 

 pint had stood aside for twelve hours, there was the merest trace of 

 a sediment at the bottom of the vessel. The microscope showed 

 this to consist of parenchymatous cells, with here and there a group 

 of the wheel-like cells which botanists, I think, term sphere- 

 crystals. The sap was slightly heavier than water, in the propor- 

 tion of 1005 to 1000. It had a faintly sweet taste and a very 

 slight aromatic odour. 



* In 'Nature' for April 5th, 1883, Mr. F. M. Burton, writing, on March 

 28th, from Highfield, Gainsborougli, says : " A remarkable instance of the strong 

 up-rusli of sap in trees at this time of the year occurred here dm'ing the late 

 severe weather. The boughs of a sycamore overhanging a road were trimmed on 

 the 21st of March during a very keen frost, and next day icicles of frozen sap, 

 varying in length from a couple of inches to a foot, were hanging from the 

 severed ends. The icicles were semi-opaque in appearance and slightly iridescent, 

 like the sheen on the moonstone, and, when put in a bottle and melted, the pro- 

 duct was pure sap. The sycamore, being one of the earliest trees to dcvelope 

 leaves, had its sap rising, notwithstanding the intense cold and late season ; 

 while a beech, which is much later in coming out, and an ash, which is usually 

 latest of all, whose boughs had also been lopped, showed no signs of bleeding, and 

 the cuts remained dry and bare. The icicles have been melted, reformed, and 

 melted again since the 21st, and still the sap is dropping from the cuts." 



