93 
weak branches lower down, in almost. every case (where they 
appeared) at the upper part of the new layer across the ring.* 
o not remember seeing any such lower, weak branches where 
this layer had not yet reached the under side of the ring. The 
leaves of the whippy, green branches formed by the stumps had 
the abnormally large leaflets that are characteristic of old or 
transplanted rubber seedlings. This apparently uninterrupted 
growth after ringing, and energetic renewal of growth after 
stumping and ringing, say much for the vitality of the Para 
rubber tree, especially when it is remembered that the trees 
under discussion had been tapped so severely that cuts for the 
tapping were made on the untouched half of the trunks before 
any bark renewal could take place on the half already tapped.” 
The effect of ringing on these trees, as described by Mr. 
Kirby, affords an example of rapid partial healing of wounds, 
involving the growth of callus and the formation of a layer of 
wood and bark over a vertical distance of two inches or more, 
within about twelve months from the time of ringing. In the 
two specimens sent to Kew, the cut appears to have been more 
than two inches across, the vertical growth made by the bridge 
being probably about 24 inches in the smaller stem, and nearly 
3 inches in the larger. The specimens measure about 36 and 
46 inches in circumference at the upper end, 1.e., at about a 
foot and a half above the soil. The trees were probably about 
twelve years old. : 
Petch} notes that ‘‘on young Hevea, wounds heal rapidly 
and completely,’ but adds that “experimental wounds, two 
and a half inches square, on twenty-three-year-old trees, have 
made very little progress towards a complete reconstruction of 
the bark in three years.” The latter statement apparently 
implies a much slower growth of callus than that observed by 
_Mr. Kirby, referable in part, perhaps, to a difference between the 
two lots of trees as to age and vigour, and possibly depending 
also on the difference in the nature of the wound. © 
In the case of some doubly ringed Hevea trees (said to be 
twelve years old, and badly grown), described by Petch,t it was 
found that, after fifteen months, complete or partial healing of 
one or both rings had taken i in nine out of sixteen trees. 
Each of the two rings was one inch wide. 
These data horatah include any record of such rapid growth 
of callus as that observed by Mr. Kirby. 
The lack of appreciable damage to the top growth twelve 
months after ringing, as noted by Mr. Kirby, is not very surprising 
in a tree with a large amount of sap-wood like Hevea. ae 
sap-wood was in fact found to extend right to the ea of t. m8 
larger of the two specimens. Hence, although the wo Sts ; 
by ringing had, no doubt, become dead, dry and incapable o 
* Cf Petch, The Physiology and Diseases of Hevea brasiliensis, 1911, 
"+ Petch, loc. cit., p. 71- t Petch, loc. cit., p. 70. 
