August, 1910.] 



165 



Correspondence. 



shall be grateful for a reply at your 

 convenience. 



I am, Sir, &c 

 CARL C. HALLING. 



[The best book on Volatile Oils is 

 Gildemeister & Hoffmann's Volatile Oils, 

 translated by E Kremers (Milwaukee, 

 U. S. A., 1900, about $10). On oils in 

 general there is Lewkowitsch's Chemical 

 Technology of Oils (Macmillan & Co., 

 1901, 36s.) and Wright's Animal and 

 Vegetable Fixed Oils (Griffin, 1903, 25s.). 

 Practical Chemistry is a somewhat 

 vague term, and it is twenty years since 

 we did any work of that kind. If Mr. 

 Hailing will write to us in our official 

 capacity, we will advise privately.— Ed.] 



RUBBER IN BOLIVIA. 



Bolivia, 17th March, 1910. 



Dear Sir,— Enclosed please find some 

 leaves of Hevea which appear to suffer 

 from a fungus disease. I would thank 

 you for information in regard to this 

 disease, also if you have similar or the 

 same in yon r parts. They are the top- 

 leaves of small rubbers, which were 

 planted last year by me. They have 

 all been healthy until January, but at 

 present the sickness is spreading. The 

 highest plants in the nursery measure 

 225 cm. medium 140 cm. At present they 

 are one year from seed. 



In your July number I find discussion 

 re the forming of Rubber pads below 

 the bark. 



It may be of interest to you to learn, 

 that in these parts our men brine; fre- 

 quently Rubber pads and lumps which 

 weigh up to 10 lbs. They occur almost 

 exclusively ou trees which have never 

 been touched. The trees which exude 

 are characteristic, as in being worked 

 they bleed very slowly and the milk is 

 of more than creamy consistence. The 

 lumps occur under the bark though 

 frequently the amount is so great that 

 it forms in big lumps in the ground, 

 especially on trees which have the trunk 

 exposed to where the surface roots 

 divide from the taproot. 



I have experimented with the new 

 tapping system, but up to date have 

 been unable to come to a satisfactory 

 conclusion if it is practicable in this 

 country. The tools are rather weak for 

 the heavy work, which we have to 

 expect from them, as our trees on 

 the av. measure 150 cm. circumference 

 and the bark is hard. The handles of 

 some would need improvement also ; 

 this can be remedied easily, but the 

 labour is rather unsatisfactory. 



The best yielding rubbers grow on 

 steep slopes, between broken rocks 

 either sandstone (red) or slate. Whilst 

 they occur in varying altitudes from 

 ca. 4,500 ft., they yield best in the lower 

 parts, though the plains of the main 

 river carry only rubber trees on red 

 loam. The river sediment does not 

 favour them. The elevation s.L of 

 Chiuiri is less than 1,000 ft. 



Thanking you in advance for your 

 kind reply. 



Yours, etc., 



ENQUIRER. 



Inclosure : Leaves under separate 

 cover : 1 piece Lump rubber. 



[The Government Mycologist reports 

 as follows : — " I should scarcely call this 

 lump a pad. Our rubber pads were as a 

 rule planoconvex discs, circular in out- 

 line and only a few centimetres in dia- 

 meter. They occurred between the 

 wood and the bark, especially alter the 

 bark had been scraped. A small patch 

 of bark died and split away from the 

 wood ; and the latex flowed in between 

 from the surrounding healthy bark. 

 There was not necessarily any exuda- 

 tion of latex, though some did exude 

 occasionally. The leaf disease is new 

 to me. The small subangular spots bear 

 a fungus on the under surface which is 

 probably the cause. From the spores 

 present, it would be classed as a Scoleco- 

 trichum; but they appear immature and 

 distorted as though they had developed 

 after the specimen was packed, and it is 

 quite possible that the fungus is really a 

 Cercospora. We have a similar disease 

 of nursery plants caused by Helminthos- 

 porium hevece, but it is not considered 

 serious. Another leaf disease of nursery 

 plants (Hevea) has just been recorded 

 by Surinam ; in this case the fungus has 

 not yet been identified, but from the 

 illustration it differs from both the 

 Ceylon Helminthosporium and these 

 Bolivian specimens. Spraying with 

 Bordeaux mixture would be advisable 

 if the disease is really serious ; but it is 

 difficult to make liquid adhere to Hevea 

 leaves."— Ed.] 



LANDOLPHIA. 



Sir,— On page 359 of your April number 

 appear some queries with regard to 

 Landolphia. 



Between 7 and 8 years ago I ploughed 

 and harrowed an acre of ground and 

 sowed it with Landolphia Kirkii at 

 stake at 6 ft. distances, using Grevillea 

 robnsta, Hautvolfia inebrians, Ceara 

 rubber and native species of Ficus, 



