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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 Acker ingae 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 this is 

 especially the case in soft wood trees, or trees with soft sap wood. 

 The Dipterocarpacece, all exude resin or oil; Anacardiaceoe, a black 

 resin; Burseraceae, resin; Apocynacece, Sapotacex, all the big Urti- 

 cacecex and many of the Euphorbiaceos latex ; Guttiferoe, a gum resin 

 Levuminosoe (Pterocarpus, etc.) Styracece (Slyrax) H ypericineoe 

 [Cratoxylon) Loganiacece, {Fagrcea), Conifer w, and Palms, all when 



