Observations on Latex and its Functions 1 , 
BY 
JOHN PARKIN, M.A., 
Trinity College , Cambridge. 
With Plate XII. 
URING the year 1898 and the early part of 1899, while 
-L/ engaged in Ceylon as temporary scientific assistant 
to Mr. Willis, the Director of the Royal Botanic Gardens, 
Peradeniya, I was occupied in investigations on caoutchouc- 
yielding trees, chiefly Hevea brasiliensis , Miill.-Arg., (Para 
Rubber), and Castilloa Markhamiana , Markham, (a Central 
American rubber-tree) 2 . The principal results of this eco¬ 
nomic work are contained in one of the circulars 3 of the 
Royal Botanic Gardens, Ceylon, which is intended primarily 
for those interested in rubber-cultivation. 
1 A short abstract of this paper was read to the British Association, Sec. K, 
Dover, 1899; see Ann. of Bot., Dec., 1899. 
2 The Castilloa trees introduced into Ceylon in 1876 have hitherto been con¬ 
sidered to belong to the species C. elastica, the well-known Mexican rubber-tree. 
They have recently been shown to belong rather to a closely allied species— 
perhaps hardly more than a variety of C. elastica —which is found in Panama and 
known as C. Markhamiana , Markham (not Collins). See Willis, Panama Rubber 
(Castilloa ), R. B. G. Ceylon, April, 1899. 
3 Caoutchouc or India-rubber, it origin, collection, and preparation for the 
market, &c. Circular, R. B. G. Ceylon, June, 1899, pp. 105-168. 
Annals of Botany, Vol. XIV. No. LIV. June, 1900.] 
