Gums, Resins, 



8 



[January, 1912- 



of them may be much greater than if 

 the caoutchouc globules were not there. 

 The most important function of the 

 globules is however probably the main- 

 tenance of a balance in the concentra- 

 tion of certain of the dissolved consti- 

 tuents. If an attempt were made to 

 remove the substances adsorbed by 

 caoutchouc globules by removal of these 

 from the solution, say, by bringing the 

 globules into fresh water, could this be 

 done, a part only of the adsorbed sub- 

 stances would be given up to the water ; 

 and with each succeeding treatment less 

 and less would go into solution. If the 

 amounts removed were plotted against 

 the times of treatment, we should find 

 the relationship to be hyperbolic, this 

 being the characteristic of all adsorption 

 phenomena. Hence to whatever extent 

 the adsorbed food constituents of the 

 latex may be drawn upon by the plant 

 there will always remain a reserve in 

 this state. 



These considerations may be taken to 

 point in favour of a reserve food theory 

 of the latex function. Such a conclusion 

 would, however, be quite unwarranted 

 at this stage. Before any conclusion 

 can be reached we require direct experi- 

 mental evidence, and, as already ex- 

 plained, this can only be obtained by 

 systematic observations and analyses of 

 tne latex over a considerable period. 

 This should include the wintering period, 

 and the trees should be tapped at 

 regular intervals during the experiment. 

 Analyses giving the percentages of 

 caoutchouc only are quite valueless for 

 this purpose, as are also isolated analyses 

 where the conditions have not been re- 

 corded. Whatever the results of such 

 systematic work may be, the fact re- 

 mains that much of the soluble con- 

 stituents in the latex must be adsorbed 

 by the globules, whether of caoutchouc 

 or resin, and that such adsorbed mate- 

 rial is differentiated as regards avail- 

 ability &c. from the remainder. The 

 data at present available is insufficient 

 to enable us to judge which of the 

 soluble constituents are likely to be 

 adsorbed to any considerable extent by 

 the globules, but their selective action 

 may play an important part. This 

 function of the suspended globules is 

 equally applicable to all latices, whether 

 caoutchouc or resin predominates. The 

 globules may have other functions, but 

 in this particular one, that is, as a 

 vehicle for the food constituents, may 

 be found their economical importance 

 for the plant. 



THE " SERINGUEIRAS " OR RUB- 

 BER TREES OF THE AMAZON. 



(Prom the India Rubber World, Vol. 

 XLV., No. 2, November 1, 1911.) 



A Portuguese Description of 

 Rubber Gathering. 

 The seringueiras Heveas produce the 

 best known rubber. The basin of the 

 Amazonian rivers is the country on 

 which the different kinds of trees are 

 scattered, unequally grouped, depend- 

 ing upon the nature of the ground, alti- 

 tude, its dampness, etc. There are 

 several varieties of rubber trees. We 

 note twenty-one different kinds, of 

 which five take a prominent part 

 (Huber). 



The rubber tree " rana " or "mangue" 

 (Hevea guyanensis or siphonia elastica) 

 will grow in a very damp ground, nearly 

 always inundated, situated at the 

 mouths of rivers. This tree does not 

 give a very important product. 



The rubber tree " branca, vermelha 

 ou preta" white, red or black {Hevea 

 brasiliensis) is found in groups on the 

 islands and at places of inundations, 

 from the middle upward to the high 

 parts of basins of nearly all the Ama- 

 zonian tributaries. It is also found on 

 solid ground (especially the red variety, 

 which is the least milky) and in places 

 filled with dampness during most of the 

 year. This rubber tree produces the 

 largest quantity and the best class of 

 Amazonian rubber. 



The rubber tree " puca" (Hevea viri- 

 dis) yields latex of an inferior quality. 

 The rubber tree ''barriguda" (Hevea 

 spruceana) is frequently encountered 

 on solid and high ground, between the 

 two rivers and in the vicinity of the 

 interior lakes. The latex is not of a 

 good quality, but is used in the mixture 

 of other better varieties of rubber. 



The rubber trees '• itauba " or yellow 

 (Hevea Cuneata), which produces a 

 rubber of good quality, lives best on 

 high, dry grounds, 



The rubber trees are found in nearly 

 all the Amazonian territory, from the 

 sea level up to the altitude of 600 meters 

 (about 2,000 fett) and more, but the best 

 quality is encountered on the islands 

 lying at the mouths of big rivers, and in 

 the high basins of the principal Ama- 

 zonian tributaries, principally the Ma- 

 deira, the Purus, the Jurua, the Javary 

 and their own ramifications. 



The longevity of the rubber tree is not 

 known exactly— it may live one hundred 

 years or more. The milk production 



