May 1908.] 



415 



Saps and Exudations. 



Piauhy for the purpose of investigating 

 the sources of Manicoba. His results 

 have recently been published in Notiz- 

 blatt des Kbnigl. botanischen Gartens 

 und Museums zu Berlin, Dahlem, No. 41 

 (Bd. V.), of Novemer 27th, 1907, where 

 diagnoses of the three new species of 

 Manihot are given, and a further and 

 more detailed account of these newly- 

 discovered sources of rubber has ap- 

 peared in Der Tropenpflanzer, No. 12, for 

 December, 1907. 



From the Consular Report on the 

 trade of Bahia, quoted above, it seems 

 probable that these species are likely to 

 be of considerable importance, and the 

 following account has therefore been 

 compiled from the information contained 

 in these papers. Dr. Ule undertook two 

 journeys into the States of Bahia and 

 Piauhy under the auspices of the Bahia 

 Rubber Syndicate of Leipsic in the year 

 1908. In the interior two distinct and 

 nearly related rubber-yielding species 

 of Manicoba were found, the one grow- 

 ing on the mountains of the right bank 

 of the Rio San Francisco, and the other, 

 confined to the country at some distance 

 from the left bank, occurring especially 

 in the adjoining State of Piauhy. The 

 latter appears to be the better species. 

 One species was discovered in the 

 wooded steppes of the Serra do San 

 Ignazio growing in places where the 

 Maugabeira {Hancornia speciosa) also 

 nourishes. This Manicoba, however, 

 grows rather on the rocky country 

 (Felsen formation), and is thus a true 

 mountain plant. — Royal Botanic Gar- 

 dens, Kew, Bidletin of Miscellaneous 

 Information, No. 2, 1908. 



THE NATIVE RUBBER TREE OF 

 BRITISH GUIANA. 



(Concluded from p. 305.) 



Source of the Rubber. 



So far as I have been able to ascer- 

 tain, it seems probable that Sapium 

 Jenmani is the main, if not the only, 

 source of the rubber that has hitherto 

 been obtained from British Guiana. Mr. 

 Jenman's samples were obtained from 

 this species, also all of the specimens 

 collected by Messrs. Ward and Beckett, 

 and this is the species which occurs 

 most abundantly of the three in the 

 forest. 



The species of the coast lands identi- 

 fied by Mr. W. B. Hemsley at Kew as 

 Sapium aucuparium, Jacq., apparently 

 yields little or no rubber. A small 

 quantity of the latex collected from 



a fruiting tree of unknown age growing 

 in the Botanic Gardens seemed to 

 consist chiefly of an extremely sticky 

 resinous substance which I have mention- 

 ed before as employed by boys for 

 catching birds. When dry it becomes 

 hard and brittle. 



Our experience however does not 

 agree with the accounts given of the 

 tree known as S. aucuparium (?) grow- 

 ing in other parts of S.America. Dr. 

 Huber of the Para State Museum writ- 

 ing of Para Rubber says : " Little of it 

 is pure Hevea rubber, but usually a 

 mixture of the latices of H. brasiliensis 

 and Sapium aucuparium. The rubber 

 of <S'. aucupariam has seldom been 

 marketed alone, and very little can be 

 said definitely of its value. But when 

 mixed with the Hevea latex a rubber 

 is produced not to be distinguished from 

 the supposeed pure Hevea rubber." 



The"virgeu" rubber of Colombia of 

 which hundreds of tons were exported 

 to the United States of America be- 

 tween 1880 and 1890, obtained by the 

 ruthless cutting down of the trees to 

 almost complete extermination, was 

 obtained from a Sapium identified at 

 Kew as S, biglandulosum (S. aucu- 

 parium), but lately some doubt has been 

 thrown upon the correctness of this 

 identification. 



To reconcile these accounts with our 

 own experiences, two explanations may 

 be brought forward, either that all the 

 trees of S. aucuparium occurring in 

 the coast lands of British Guiana are 

 comparatively young trees, or that more 

 than oue distinct species have been includ- 

 ed under this name. With regard to the 

 possibility of the former, Dr. C. Bovallius 

 of the Essequebo Exploration Company- 

 stated in a lecture delivered at a meet- 

 ing of the Royal Agricultural and Com- 

 mercial Society on " Rubber Cultivation 

 in British Guiana," that S. aucuparium 

 would not give good results at sea level, 

 and that it was quite impossible to get 

 old Sapium trees, because when they 

 began to get about ten inches in diame- 

 ter, they died. Now it is known with 

 many rubber yielding trees, of which 

 the Hevea brasiliensis is an exception, 

 that the latex of young trees is com- 

 paratively poor in rubber and relatively 

 rich in resinous substances, and that not 

 until the trees have reached a certain age 

 will they yield a good rubber. The 

 same may be the case with S. aucupa- 

 rium. 



The probability of the latter explan- 

 ation being nearer the truth will be 

 sufficiently evident to any one Avho has 

 any knowledge of the extreme variability 

 of the Sapiums and of the confusion 



