91 
tions regarding parasitism and plant diseases generally are en- 
countered, and a new science of phytopathology is being built up 
on the basis of the intimate relationship between host-plant, 
parasite, and external conditions. It is essential for the progress 
of mycological science in this country that we should keep in 
close touch with current developments and trends of thought in 
the United States. Mere knowledge of the literature does not 
sufficiently satisfy this need, as the value of published work is 
often difficult to appraise at a distance and trends of thought are 
usually in advance of publication. The practice of sending British 
mycologists to the United States in response to the annual 
invitations that have been issued during the past few years by the 
American Phytopathological Society is a sound one, and its cost 
will be more than repaid in the increased efficiency of their work. 
To the Bureau of Mycology there is a special advantage over 
the general one referred to above, in that both as a centre for 
distributing information and an organization for working out the 
parasitic fungus flora of the outlying parts of the Empire we will 
require all the assistance we can get from other workers. As a 
result of my visit, I feel that we can rely confidently on receiving 
a great deal of help from workers in the United States. 
-XI.—RECOVERY OF HEVEA TREES AFTER 
RINGING 
When at the Agege plantation, Nigeria, in the spring of last 
year (see K. B., 1921, p. 234), I was interested to see the way in 
which the Hevea rubber trees had recovered from the ringing of 
the stems which had been done with the object of killing 
superfluous trees in order to thin out the plantations. 
Mr. A. H. Kirby, late Asst. Director of Agriculture, Southern 
Provinces, Nigeria, in whose company I visited the plantation, 
has been good enough to send over two specimens of ring} 
trunks to Kew from one of which the photograph, here reproduced, 
has been taken. Unfortunately the trunks suffered a good deal 
of damage in transit, but’they show remarkably well the bridging 
across of the ring, more than two inches broad, by the growing 
down of callous growth from the cortical tissues above the ring 
to meet and rejoin with the cortical tissues on the lower side of 
the ring. On account of the rate at which this growth was 
made, and certain other particulars in the behaviour of the 
ringed trees, it appears desirable that the results of this ringing 
experiment should be recorded, and Mr. Boodle has added some 
notes on the specimens. 
. A. W. H. 
Mr. Kirby has kindly furnished the following particulars of 
the ringing of the trees and of their recovery he Para Sa 
trees at Agege, that were tapped severely before their inten 
eae 
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