104 
collected what is known or suggested by various botanists,' but 
what a little it is! No doubt as Groom suggests the functions 
of latex are different for different plants. 
The various suggestions for its use to the plant are as a water 
store, as a reserve food, as a protection against insects or fungi, 
or finally it may be an excretory product. 
In the case of Para rubber at least I should be rather doubtful of 
its being either a water-store or a protection against excessive trans- 
piration. Were latex destined for this purpose we should have an 
excess of laticiferous plants in xerophytic localities. This is how- 
ever not the case, a very large part of the trees of our flora here are 
laticiferous. We have plenty of Apocynaceous trees and climbers 
Urticaceous trees, Ficus, Artocarpus, > loetia and Sapotaceous trees 
Palaquium , Payena , Bassia, etc. 
Of these trees nearly all are inhabitants of permanently wet 
jungles, and so far from being specially protected against drought 
by this latex system, many of them have considerable difficulty in 
standing exposure to sun, and those plants of these orders which 
grow in exposed places seem to have less latex than their congeners 
living in shaded permanently wet forests. There are of course, 
laticiferous plants which grow in deserts, such as Manihot Glaziovii 
and the Euphorbias but the proportion is not so large I think, as it 
is in the Rain belt. 
The little laticiferous Phyllanthus Urinaria grows side by side 
with non-laticiferous weeds like Spermacoce , and Vandellia on our 
paths exposed often to very hot sun; yet Phyllanthus can stand the 
sun no better than the other weeds. In Christmas Island when we 
were there in a very hot and dry period the plant that appeared to 
suffer most was the laticiferous Ochrosia Ackeringae which remained 
quite drooping and wilted all day, while the other non-laticiferous 
trees were fresh and green, 
As a reserve food one may doubt its use, as it appears in most 
cases to contain so little sugar or starch or any other food substance 
and as there seems no natural way in which it is removed from the 
plant it is hard to see how it can be considered merely as an excre- 
tory product. 
There remains of suggestions only the one of its acting as a pro- 
tection against the intrusion of fungus spores and insects into 
wounds. That it does so is obvious to every one. Is this of suffi- 
cient importance to be at least a main use of the latex? I would 
point out that the greater part of the trees of the equatorial belt, 
the rain forest region, are provided with either a latex, gum or resin, 
which exudes in a wound as soon as it is made and that thi^ is 
especially the case in soft wood trees, or trees with soft sap wood. 
The Dipterocarpacece , all exude resin or oil; Anacardiacece y a black 
resin; Burseracese , resin; Apocynacece, Sapotaceas , all the big Urti- 
cacecese and many of the Euphorbiaceoe latex; Guttiferce , a gum resin 
Lzvuminosce ( Pterocarpus , etc.) Styraceoe ( Styrax ) Hypericineoe 
( Cratoxylon ) Loganiaceae, ( Fagma ), Conifer se, and Palms, all when 
