40 CENTRAL AMERICAN RUBBER TREE. 



some of the companies doing- business on the Isthmus of Tehuantepec, 

 where there is a very distinct dry season, still feel it necessary to omit 

 this fact from their prospectuses or to represent their plantations as 

 always moist. The incorrectness of this claim not then being realized, 

 the extent of the dry season of the west coast of Guatemala and 

 the adjacent Soconusco district of Mexico was observed with much 

 interest. 



<; HEATER ABUNDANCE OP CASTILLA ON THE DRIER PACIFIC SLOPE. 



The total rainfall of a place affords but the slightest intimation of 

 its climate in relation to yegetation. A sudden, heavy shower may 

 wet the soil much less than the same amount of water falling as a steady 

 rain, and in the supply of w T ater to plants the difference is even greater; 

 the period during which the atmosphere and soil are moist is of impor- 

 tance to them, but not the amount of water which patters off their 

 leaves or falls into the rain-gauge. Humidity even to the point 

 of saturation for six months may be of no avail to plants unable to 

 survive an equal period of drought. The lowland forests of the west- 

 coast districts of Guatemala and southern Mexico, while composed in 

 the main of the same tropical elements as those of eastern Guatemala, 

 yet showed a striking deficiency of plants requiring continuous 

 humidity. " Nevertheless wild Castilla seems to have existed in the 

 past as in the present in far greater abundance, the wild product hav- 

 ing long been an article of export in quantity far more considerable 

 than from the eastern districts. 



FREER FLOW OF MILK IX DRIER REGIONS. 



A second fact contrary to the popular supposition that rubber pro- 

 duction is confined to continuously humid climates was encountered 

 when it was found that, in spite of the greater dryness, the milk 

 flows down from the rubber trees of Soconusco with a freedom 

 unknown in eastern Guatemala, where it merely oozes out into the 

 gashes made by the "uleros." Dr. Paul Preuss, who studied rubber 

 culture in Trinidad, Mexico, and Central America for the German 

 Colonial Society, did not see rubber flow down from the wounds made 

 in tapping, and seems to have left America in some doubt as to the 

 reality of this phenomenon. He explains that the milk of Castilla 

 behaves very different^ from that of other rubber trees. The '"fish- 

 bone cut" to which he had been accustomed was found in Trinidad to 



«Such are the filmy ferns, or Hymenophyllacea*, and forest species of Selaginella; 

 also many Orehididace;e and Piperacea', largely absent from the forests between Ayntla 

 and Tapachnla, and also from the vicinity of La Zacualpa. Moisture-loving plants 

 increase with altitude as the more humid coffee districts are approached, but at no 

 lowland locality visited do they exist in any such abundance as in the forests of the 

 valley of the Polochic River, in eastern Guatemala. 



