July, 1909.] 



3 



degree up to the present time, and the 

 transference of this serai-fluid rubber to 

 sound parts of the same piece has no set 

 up tackiness at the spots to whic it 

 was applied. Further, tackiness affects 

 vulcanised rubber as well as raw rubber, 

 though the causes may be different. In 

 1906, some small glass pipettes, such as 

 are used for filling fountain pens, were 

 bought from England for use in the 

 laboratory. They were furnished with 

 red vulcanised rubber teats. Six of 

 these were wrapped up in paper and put 

 away in stock, while one, which was 



used occasionally, was kept in a drawer 

 on a cardboard tray. The teats of the 

 six in paper were found to be tacky and 

 in parts semi-liquid in March, 1909, while 

 that in the drawer (usually in darkness) 

 had flowed for a length of four centi- 

 metres along the glass tube and over 

 the cardboard. But another similar 

 pipette, with a black teat, has been kept 

 in a drawer for more than four years, 



with occasional use, and the teat is still 



sound. 



T. PETCH. 



GUMS, RESINS, SAPS AND EXUDATIONS. 



BOTANICAL PACTS FOR RUBBER 

 PLANTERS. 



By R. H. Lock. 



Recent discussions in the local press 

 on the best methods of tapping Para 

 rubber have revealed so many remark- 

 able misunderstandings of the actual 

 way in which a rubber tree grows and 

 gets its living, that it appears as if the 

 following facts, although describing 

 matters which are doubtless familiar to 

 many planters, may yet be of some 

 service to those who are not equipped 

 with a knowledge of botany. We shall 

 endeavour in what follows to avoid 

 technical terms as far as possible, and 

 to describe the few simple facts which it 

 behoves anyone who has charge of a 

 rubber plantation to understand, in 

 language which can be grasped without 

 any previous scientific training what- 

 ever. 



The organs or parts of a plant may be 

 divided into two chief kinds : on the one 

 hand those which are concerned with 

 growth and feeding, namely, the leaves, 

 roots and stem, and on the other hand 

 those which are concerned with repro- 

 duction, namely, the flowers and seeds. 

 For the present we shall disregard 

 all questions concerning the seed and 

 younger stages of the plant, and, ima- 

 gining our rubber tree to be already 

 well established and grown to some con- 

 siderable size, we shall consider the 

 growing parts of the tree and how they 

 are likely to be affected by the operation 

 of tapping. 



As already remarked, the growing 

 organs of the tree consist of leaves, stem 

 and roots. The function of the roots— to 

 take the last-mentioned organs first, is 

 firstly to hold the tree firmly upright 

 by anchoring it in the soil ; and, secondly, 

 to absorb certain substances contained 



in the soil which are essential for the 

 nourishment of the tree. Among the 

 most important of these substances, as 

 is well known to all who are familiar 

 with the application of artifical manures, 

 are certain compounds of nitrogen, 

 phosphorus and potash. 



Before these materials can be made 

 use of as food by the different parts of 

 the plant, it is necessary for them to be 

 altered and combined with the still more 

 important substance carbon, which is 

 obtained only by the leaves, one of 

 whose functions is to absorb this sub- 

 stance from the air in the form of car- 

 bonic acid gas, We may compare the 

 leaves of the tree to so many minute 

 kitchens in which the different in- 

 gredients of the tree's food are prepared 

 and compounded into a form in which 

 they can be utilized by the roots, stem 

 and other organs. 



We now pass to the functions of the 

 stem or trunk of the tree. The first 

 of these is to support the leaves in a 

 position where they are well exposed 

 to air and sunshine, and the second is 

 to conduct the necessary mineral sub- 

 stances from the roots to the leaves, 

 and also to conduct the elaborated food 

 supply downwards from the leaves to 

 the roots. 



The trunk of a tree is well known to 

 consist of two main portions — -the wood 

 and the bark, If the bark is stripped 

 from the wood the separation takes place 

 at an extremely soft and delicate layer 

 of tissue known as the cambium. Chan- 

 nels for the conduction of sap occur both 

 in the wood and in the bark, and two 

 entirely different streams of sap are 

 associated with these two regions. An 

 upward current of sap occurs in the 

 outer part of the wood, by means of 

 which current the mineral substances 

 absorbed by the roots are carried to the 

 leaves in a state of very weak solution. 



