Vol. X. No. 243. 



THE AGRICULTURAL NEWS. 



265 



from the plants Calotropls procera tod C. gigantea, 

 the former of which occurs in the West Indies, and is 

 known as French cotton. The fibre is obtained from 

 the stems of these species, and difficulty is caused in 

 its working, on account of the fact that the long fibres 

 show weakness at the parts which were originally 

 situated at the internodes. 



It does not seem that there is any marked differ- 

 ence between the two species of Calotropis mentioned; 

 they have much the same habitat. In India the fibre 

 of Calotropis is usually designated as Madar silk. 



Rainfall in Antigua, 1910. 



The statistics of the rainfall in Antigua for 1910, 

 prepared by the Superintendent of Agriculture for the 

 Leeward Islands, show that the precipitation in that 

 year amounted to 3-l<-77 inches. 



The average rainfall in the island for the thirty- 

 seven years, 1874-1910, is 45 03 inches, so that the 

 precipitation for last year was 1026 inches below the 

 average. This is the lowest rainfall for the last twenty 

 years, with the exception of that in the year 1905, when 

 the average total rainfall recorded was 31 40 inches. 



Effect of Nitrate of Soda on the Flow of Ceara 

 Latex. 



In the Agricultural Ketvs, Vol IX, p. 107, 

 reference was made to experiments in connexion with 

 the flow of latex from Ceara rubber trees that 

 are described in Bulletin No. 19 of the Hawaii Agri- 

 cultural Experiment Station. Attention is also given 

 in this Bulletin to the effects of nitrate of soda on the 

 flow of latex. 



In an experiment described, the capacity to yield 

 of a group of trees was tested by means of uniform 

 tapping. Nitrate of soda was then applied to two of 

 the groups of trees, while a third was left as a control. 

 In the case of three trees receiving i-H>. of nitrate of 

 soda each, the yield of dry rubber was 23 oz ; from 

 a similar number i-eceiving {-lb. of nitrate of soda, it 

 was 13 oz.; and from the three control trees, 12 oz. 

 The manner of application of the nitrate of soda was to 

 place it in the soil at a depth of 3 or 4 inches, and at some 

 distance around each tree. There was a good rainfall, 

 and it is stated that the effect of the nitrate of soda 

 upon the flow of latex was exhibited within twenty- 

 four hours. 



Further experiments have been carried out, and it 

 is concluded from all the trials that the flow of Ceara 

 latex may be temporarily stimulated by applying 

 nitrate of soda. 



The Planters' Cltronide for April 15, 1911, gives 

 a description of similar experiment.s carried out on 

 estates in Southern India. In one of these the results 

 were not veiy conclusive, but it was indicated that the 

 application of nitrate of soda caused an increase in the 

 flow of latex and yield of rubber. In another case, 

 more elaborate trials appeared to show that, under the 

 conditions of the experiments, the best quantity of 



nitrate of soda to apply is i-tb. per tree; this increased 

 the yield of wet rubber from 1 oz. 10§ drs. to 

 2 oz. 5f drs. per tree, in eight tappings, and the yield 

 of dry rubber was increased by 5 drs. per tree in the 

 same time. Mr. Rudolph D. Anstead, in reporting 

 these experiments, expresses agreement with the con- 

 clusion that further work is required before any 

 decision can be made as to the proper means of 

 manurial treatment with nitrate of soda for Ceara 

 rubber trees. 



The Production of Hydrocyanic Acid in Leaves. 



The production of hydrocyanic (prussic) acid in 

 parts of plants, such as the germinating seeds, stems 

 and leaves, has received attention in the Agricultural 

 Neivs from time to time. In the case of the last, an 

 interesting review is given of recent work, in the 

 Anmial Reports of the Progress of Chemistry, for 

 1910, issued by the Chemical Society, p. 214. 



The investigations have shown that the action of 

 chloroform and similar anaesthetics on leaves is to pro- 

 duce hydrocyanic acid, the action being most rapid at 

 high temperatures. It was found that, in such experi- 

 ments, solutions of the substances may be employed 

 instead of the compounds themselves, as water has no 

 influence in causing the production of hydrocyanic acid. 

 An extension of the trials has shown that many other 

 substances than chloroform, such as ammonia, carbon 

 disulphide, various alcohols, benzene and acetic acid, 

 will produce the effect. 



It appears that the action arises as a result of the 

 concentration of the contents of the cells of the leaves, 

 and it is suggested that the experiments will eventu- 

 ally provide an explanation of the significance of the 

 possession of ethereal oils and scents by various plants. 



Tapping Experiments with Ceara Rubber in 

 Uganda. 



The results of two months' (February and March) 

 tapping of twelve Ceara {Manihot Glaziovii) trees 

 belonging to the Mabira Forest (Uganda) Co., Ltd., are 

 contained in a Supplement to the Uganda Ofjficial 

 Gazette for May 15, 1911. The details show that, 

 whereas the trees tapped on the pricking system gave 

 a decrease of 5951 per cent, in the second month, those 

 which were tapped on the paring system, with no 

 pricking, yielded an increase of 2423 per cent. 



The total amount of dry rubber obtained from six 

 trees by paring was 29915 gm., which is equivalent to 

 2493 gm. per tree per month, or an average of 29915 

 gm. per annum; so that assuming a constant yield of 

 this nature, the rubber given by each tree during 

 a year would be 006 lb. 



Further work will determine if the yield is main- 

 tained during the year, and it may be mentioned in this 

 connexion, that February was a very dry month and 

 that the rainfall for March was below the average. 

 The circumstance that is most likely to possess the 

 greatest influence in the matter is the effect on the 

 trees of continuous tapping. 



