167 
A special chisel, made by Mr. Jowett at the suggestion of 
the author of the paper, has been successfully used in Trinidad, 
and a specimen was shown at the meeting. 
THE METHODS OF TAPPING CASTILLOA RUBBER TREES 
IN MEXICO AND THE YIELD OF RUBBER WHICH THE 
TREES FURNISH. 
By AsHMORE Russan, 
Director of the Soconusco Rubber Plantations, Lid.; London 
Director of La Zacualpa Plantation Company. 
[ ABSTRACT. ] 
The paper deals : — 
(a) With the cultivation of Castilloa rubber on La Zacualpa 
and other plantations in the District of Soconusco, State of 
Chiapas, Mexico, and also with a plantation in the State of 
Oaxaca, Mexico. 
(b) With the methods. employed in tapping cultivated 
Castilloa rubber trees in Mexico and the tapping-knives used. 
(c) With the yields of rubber obtained on a commercial scale 
from cultivated trees of different ages, and with the reputed 
yields from wild trees. 
(d) With the yield of cultivated Castilloa rubber trees in 
comparison with that of Hevea brasilensis, and shows why 
the Castilloa may be more suitable for cultivation in Mexico 
than Hevea brasiliensis, owing to the deficiency of labour. 
(e) With experiments which have been made to increase the 
production, and points out that, in the author’s opinion, this 
can only be done by better cultivation. 
(f) With the different species of Castilloa to be found in 
Mexico and Central America from the point of view that the 
Castilloas are all of the same species, and that the difference in 
yield, etc., is probably due to environment. 
{ Discussron. ] 
Sir THomas Hotpicu: Mr. Chairman—I can add nothing 
really valuable to what Mr. Russan has said. In regard to 
Mexico, no one can speak with such authority as he can. But 
with reference to the varieties of the Castilloa tree, I would like 
to ask Professor Dunstan whether such varieties of Castilloa 
occur. I have seen it stated, though I cannot say positively 
where, that no less than seven different kinds of Castilloa are 
