and Magazine of the Ceylon Agricultural Society,— October,' 1911. 



879 



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tchouc in all probability does not exist as schu 

 in the latex, but is produced during coagulation 

 from simpler bodies similarly constituted 

 chemically. It is itself a compound of carbon 

 and hydrogen and is chemically comparatively 

 inactive. There is, therefore, some probability 

 that it is an end-product and incapable of being 

 further utilised by the parent. Much more re- 

 quires to be learnt, however, concerning the 

 changes which occur in latex in different parts 

 of the plant and under different conditions, be- 

 fore any accurate conclusions can be arrived 

 at as to the significance of the presence of 

 caoutchouc. 



Enzymes have been demonstrated in the latpx 

 of some plants. Ficus carica and carica papaya 

 (papaw) contain peptonising enzymes. The 

 presence of an oxidase has been demonstrated in 

 the latex of Hevea ; the occurrence of black 

 latex is ascribed to this enzyme. The presence 

 of enzymes is significant of the occurrence of 

 active changes in the latex. 



In addition to the abovementioned func- 

 tions of latex two others occur, viz. — the 

 sealing of wounds and the protection of the 

 plants from animals. Latex containing caou- 

 tchouc coagulates quickly, and the coagulated 

 mass serves to seal wounds more or less 

 effectively. In seme plants the latex tubes 

 branch close to the surface and thus facili- 

 tate the sealing of wounds by the juice, In 

 other plants hairs containing latex are present 

 on the floral bracts and are thus regarded as 



serving to protect the flowers from animals ; 

 while the occurrence of poisonous substances in 

 latex is no doubt an efficient means of protection 

 against certain animals. It is not uncommon to 

 find insects in the neighbourhood of Hevea 

 plantations bearing masses of coagulated latex 

 on all parts of their bodies in such quantity as to 

 considerably hinder their movement ; and it is 

 believed that the insect pests of Hevea would 

 cause considerably greater damage, were it not 

 for the protection offered by the latex. 



The occurrence of these two functions of latex 

 is clear ; but, they are in all probability not 

 primary functions and can ody be regarded as 

 incidental. With regard to the two first named 

 functions, the one of conducting food-material 

 and theother of receiving products of excretion, 

 it is uncertain as to which was the primary one. 



The relation of latex to the life of the parent 

 possesses for more than mere scientific interest. 

 The recognition of the laticiferous tubes as a 

 means of conducting plastic food material is of 

 itself of primary importance, inasmuch as such 

 problems of practical importance as tapping, 

 systems of tapping, bark renewal, etc., are 

 closely connected with it, while an accurate 

 knowledge of the significance and mode of 

 formation of caoutchouc must be of considerable 

 value to the practical cultivator. 



Keith Bancroft, b.a. 

 —Straits Agricultural Bulletin for Sept., 1911, 



