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Mex 



spoken of. I have seen the plant, but have not been able to 

 obtain a sample of the product, which I understand, however, 

 somewhat resembles the Guayule rubber." 



In addition to this article, another communication on the same 

 subject by Dr. R. Endlich appeared in Der Tropenpflanzer 

 (July, 1907, under the title "Uber den gegenwartigen Stand und 

 die Aussichten der Guayuleindustrie (on the present conditions 

 and the prospects of the Guayule industry"). From it the 

 following observations may be added to what has been said above. 



Dr. Endlich recognises a central area of 75,000 square Rm. 

 (28,950 square miles) of Guayule land, comprising the northern 

 parts of Zacatecas and San Luis Potosi, the eastern part of Durango 

 and the south of Coahuila. Then there are smaller areas in 

 Nueva Leon, Chihuahua, New Mexico, Arizona, and Texas. 

 About one-tenth of the central "area may be said to be stocked 

 with Guayule, yielding on the average i-ton per hectare (Hon per 

 acre). The total supply of Guayule available is estimated at from 

 400,000 to 500,000 tons, but Mr. Hexly C. Pearson, the American 

 expert of the "India Rubber World" (New York), allows only 

 300,000 tons. Investigations into the yield of rubber made by a 

 competent chemist at Jimulco gave a result of 7-12 per cent., 

 which agrees well with Pearson's figures of 6-11 per cent. 

 Dr. Endlich, quoting from Pearson (in - El Finaneiero mexicano, 

 15 de Avril de 1907) states that the export of Guayule rubber' up to 

 the end of January, 1907, was 6,100,000 lbs., of which 2,100,000 lbs. 

 go to the second half of 1906 and 700,000 to January of the 

 current year. The last prices quoted were 65 cts. gold per ID. per 

 New York, and 5'50-5'75 M. per Kg. per Hamburg. 



The extent to which Guayule land is restocked spontaneously is 

 satisfactory, as there are plenty of seeds and the seeds germinate 

 readily ; but growth is slow, ten years being about the time 

 required for a Guayule plant to become fit for profitable working. 

 By that time the stem should have a diameter of f-in. at the base. 

 As to cultivating the plant Dr. Endlich is more hopeful now. 

 Although the experiments made in that direction were on a small 

 scale, he considers the fitness of the Guayule for Potation 

 proved. Wherever soil and climate correspond to **e pnysicai 

 conditions prevailing in the Mexican Guayule region, waste land 

 might be profitably stocked with Guayule, particularly along with 

 cattle-rearing as the primary industry. So far as soil is concerned 

 the presence' of a certain amount of lime see f« to ^^* 1 ^ 

 and as to climate it should be kept in mind that ^° ^ n ™°^s 

 the Guayule shrub in the central area is limited to altitudes 

 between 900 and 1,700 m. Sloping or undulating ground would 

 answer best the situations of its natural habitats. 



Owing to the fact that Mariola (^tJ^^^num^^ 

 mistaken for the Guayule (P. argentatum)jt ^ ems desn able to 

 provide, if possible, against a repetition of ^V* 18 ™^ 1 {£ 

 following diagnostic comparison of the two plants, prepared by 

 Dr. O. Stapf, may it is hoped, serve this purpose. 

 . , A. though the structure of _ the flowers and flowe, he ads of Pa, 



