396 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lxvit. 



spots are got, and there is a beautiful demonstration in 

 miniature of the misty vapour making its escape. 



(4) The I'hycophfiein retreats like a cloud before the heat 

 (this is observable in the first experiment). 



When a metal mould of an Ivy leaf is heated and 

 pressed on the frond, one gets an impression of the same 

 size as the mould well defined in green, and three minutes 

 after removing metal, an outline beyond the contour line in 

 pale green, which latter is surrounded by another outline in 

 pale brown impinging on the natural brown. 



(5) If a heated double split ring be applied on frond, the 

 ring forms a light green circle, bordered on either side by a 

 broad green band. Towards the periphery in three minutes 

 the condition as in Ivy leaf is seen, a light green succeeded 

 by a light brown ring appearing. 



From the central brown area, corresponding with the 

 hollow of the ring, similar phenomena occur in three 

 minutes — a light brown ring next the brown (natural), and 

 a light green ring beyond. 



After an exposure to air of a few hours, and an afternoon 

 and night wrapped up in paper, and thus excluded from 

 atmospheric agency, the central brown (natural) area of the 

 manipulated frond is surrounded by a green ring, and a 

 brown occupies the place of the previous green ring. 



Towards the periphery of the figure, one finds a green 

 ring touching the natural brown of the frond, and within 

 the green ring a circle of brown. 



CowTHOKPE Oak. By John Clayton. Communicated by 



Dr. David Christison. (With Photo. Illustrations.) 



(Read 12th March 1903.) 



The oak tree at Cowthorpe, near Wetherby, is acknow- 

 ledged to be the largest in diameter of all oaks that are 

 known. It therefore commands an attention that is 

 specially its own — as a king among men — and it is 

 doubtful whether any other living tree has had as much 

 written about it as it has, for wherever books on forestry 

 in the English language are printed and read, so far has 

 spread the fame of the Cowthorpe Oak. 



