Notes. 
621 
time there he has been principally engaged in investigations on 
caoutchouc-yielding trees, chiefly Hevea brasiliensis (Para Rubber), 
and Castilloa elastica var. (a Central American Rubber-tree). The 
results of this research are contained in a recently-published 
circular of the Royal Botanic Gardens, Ceylon, entitled ‘ Caoutchouc 
or Indiarubber,’ intended primarily for those interested in rubber 
cultivation. 
The purpose of this paper is to draw attention to some of the 
observations and experiments recorded in the Circular, which, 
besides their practical value, have a general botanical interest, and 
also to make public other observations which may throw light on 
the functions of iaticiferous tissue. It is arranged in six sections. 
The main features of these are here briefly given. 
Section I is occupied chiefly with the coagulation of the latex of 
Hevea. Coagulation is now known to be brought about by the 
proteid contained in the latex passing from a soluble to an insoluble 
state. The latex of Hevea is not coagulable by heat or slight additions 
of alkalies, but is coagulable in the cold, by small quantities of acids. 
The approximate weight of acid required to clot completely 100 c.c. 
of latex has been worked out for sulphuric, hydrochloric, nitric, acetic, 
oxalic, tartaric, and citric acids. Experimental evidence points to 
the proteid in question being alkali-albumen rather than ordinary 
albumen. It has previously been called albumen. 
The behaviour of the latex towards certain saline solutions has also 
been investigated. Mercuric chloride is shown to be a powerful 
coagulator. 
Section II contains observations and remarks relating to the car- 
bohydrates of latex. 
Sugar in variable proportions is of frequent occurrence in latex. 
The little contained in the trunk-latex of Hevea seems invariably to 
be cane-sugar. 
It is suggested that the sugar may arise, in part at least, from the 
surrounding injured tissues, and may not be always originally present 
in the latex. 
The starch-rods so characteristic of the Iaticiferous tubes of 
Euphorbia and allied genera have been found still present in the 
turned and fallen leaves of the following species examined : Euphorbia 
pulcherrima , E. Bojeri, E. rothiana , Pedilanthus tithymaloides , Hura 
crepitans , Excaecaria bicolor , and Sapium biglandulosum. This fact 
