348 OBSEEVATIONS ON 



several of its boughs, and is tending to decay. Mr. Marsham 

 computes, that at 14 feet length this oak contains 1000 feet 

 of timber. 



It has been the received opinion that trees grow in height 

 only by their annual upper shoot. But my neighbour over the 

 way, whose occupation confines him to one spot, assures me that 

 trees are expanded and raised in the lower parts also. The 

 reason that he gives is this : the point of one of my firs began 

 for the first time to peep over an opposite roof at the beginning 

 of summer ; but before the growing season was over, the whole 

 shoot of the year, and three or four joints of the body beside, 

 became visible to him as he sits on his form in his shop. Ac- 

 cording to this supposition, a tree may advance in height con- 

 siderably, though the summer shoot should be destroyed every 

 year. 



FLOWING OF SAP. 



If the bough of a vine is cut late in the spring, just before the 

 shoots push out, it will bleed considerably ; but after the leaf is 

 out, any part may be taken off without the least inconvenience.* 

 So oaks may be barked while the leaf is budding ; but as soon 

 as they are expanded, the bark will no longer part from the 

 wood, because the sap that lubricates the bark and makes it 

 part, is evaporated off through the leaves. 



RENOVATION OF LEAVES. 



When oaks are quite stripped of their leaves by chaffers, they 

 are clothed again soon after Midsummer with a beautiful foliage : 

 but beeches, horse-chestnuts and maples, once defaced by those 

 insects, never recover their beauty again for the whole season. 



i[In the Pharmaceuticaljournal {or April 7, 1883 (vol. xiii. , pp. 819-20, 834-35, 

 877-78), is an account by Professor Attfield of a bleeding birch at Ashlands, Watford. 

 The tree was 39 ft. high and 7 in. in diameter. A branch, i in. diameter at lo ft. 

 from the ground, was cut across in March, before the leaves or catkins appeared. 

 Nearly a gallon a day flowed from the wound ; the flow was greater in sunshine 

 than in shade, and greater by day than by night. The fluid contained nearly i 

 per cent, of sugar.] 



