TRANSACTIONS OF SECTION K. 929 
bundle. The protoxylem of Z'richomanes spicatum, unlike the other species 
examined, resembles that of the Sehizeacee. 
The solid stele may be regarded as primitive, the Ancimia type being derived 
from it by the following steps :— 
1. Solid central xylem-mass surrounded by phloem, &c. 
2. Ring of xylem surrounding a central pith. 
3. Ring of xylem with internal phloem, endodermis, and pith. 
4. Ring of separate bundles formed by the breaking up of the above vascular 
ring, owing to large leaf-gaps. 
The Aneimia type thus explained would not be polystelic, in the morphological 
sense of the word, but the separate bundles would represent peripheral parts of an 
originally solid stele, in which the central part has been replaced by parenchyma, 
additional pieces of phloem and endodermis having been differentiated to complete 
the concentric bundles. 
6. Notes on Indiarubber. By R. H. Birrren, Cambridge. 
Starch and caoutchoue appear not to occur together. Caoutchouc occurs as 
small particles in latex, and coagulation begins with their running together. 
Certain reagents will bring this about; but it is better to avoid all chemical pro- 
cesses, any of which do harm. Two physical processes are now being used. 
(1) The latex, mixed with water, is strained and churned; the thick cream which 
rises to the surface is pressed through rollers and converted into rubber. (2) The - 
author's process consists in separating the rubber with a centrifugal apparatus. 
Details are given in the paper regarding the chemical properties of the different 
kinds of rubber obtained from Hevea, Castilloa, Manihot, Ficus, Hancormia, 
Kicksia, Artocarpus, and Clusia. The author also raises some questions of theo- 
retical interest with regard to possible relations between caoutchouc, starch, and 
resin-bodies, and indicates lines for further inquiry. 
7. Some Isolated Observations bearing on the Function of Latex. 
By J. Parkin, IA. 
The author has lately returned from a year’s sojourn in Ceylon, where he has 
been acting as scientific assistant to Mr. Willis, the Director of the Royal Botanic 
Gardens. During his time there he has been principally engaged in investigations 
on caoutchouc-yielding trees, chiefly Hevea brasiliensis (Para Rubber), and Cas- 
tilloa elastica var. (a Central American Rubber-tree). The results of this research 
are contained in a recently-published circular of the Royal Botanic Gardens, Cey- 
lon, 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 laticiferous 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 com- 
pletely 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 this latex towards certain saline solutions has also been 
investigated. Mercuric chloride is shown to be a powerful coagulator. 
1899. 30 
