231 



{vide "Schimmel's Reports," THE CHEMIST AND DRUGGIST, and 

 "Jamaica Bulletin of the Department of Agriculture"), the plants 

 being sub-species, varieties, or forms of the mother-plant, and 

 climatic conditions also exercising their influence on the secretions 

 of the organs of the plants. 



The West Indian grass oils will not for all purposes take the place 

 of East Indian oils, by reason of some of their physical properties, 

 but for certain manufacturing purposes they are admirably adapted, 

 and an extension of their cultivation on a commercial scale should 

 by all means be encouraged in our West Indian possessions, as, I 

 believe, is the opinion of Sir Daniel Morris, of the Imperial De- 

 partment of Agriculture for the West Indies, and Mr. Hart, of the 

 Botanical Gardens at Trinidad. Mincing Lane brokers also have 

 reported favourably on the lemon-grass and citronella oils from 

 the West Indies, especially as, being distilled under the super- 

 vision of Government chemists, they can be shipped in a state of 

 reliable purity — a very important consideration, and one which 

 only applies to the oils specially distilled in Java. 



The other grasses (vetiver and palma rosa) will be submitted to 

 similar examination and reported upon when the writer has ob- 

 tained from competent botanists the necessary material from the 

 different places of growth. 



THE CULTURE OF THE CENTRAL AMERICAN 



RUBBER TREE, III.* 



{Continued from Bulletin for August.) 



By O. F. Cook, Botanist in charge of Investigations in Tropical 

 Agriculture, U. S. Department of Agriculture. 



SEASONAL INFLUENCES ON LATEX. 



No theoretical consideration need interfere with the recognition 

 of any relation which can be proved to exist between the amount 

 of latex or of rubber obtainable from Castilloa and the climatic 

 conditions under which the trees are found. The most direct 

 evidence of such climatic influence is to be found in the seasonal 

 changes in the latex. Such differences in the rubber content of the 

 milk at different seasons has received little attention from recent 

 writers, though it is not a new fact, since a detailed statement was 

 published by Collins over thirty years ago : 



In Nicaragua it is found that although the hule yields the juice at all seasons, 

 the most favor;ible season is Aciil, when the old leaves begin to fall and the new 

 ones appear. During the rainy seasoi), from May to Saptember, the richness of 

 the juice diminishes. From that time to .January the rain diniinisbes and the milk 

 increases in richness, and the tree prepares to flower. The fruit appears in March, 

 during whicti month and the succeeding one the milk is at its richest. The yield 

 of caoutchouc contained in an equal quantity of milk w uild in April be 60 per 

 cent, more than in October.** 



* Extracts from U.S. Department of Agriculture, Bull. No 40, Bureau of Plant 

 Industry. 



** Report on the Caontciiouc of Commerce, 1872, p. 15. 



