44 CENTBAL AMEEIOAN EUBBER TEEE. 



season and the more the rain extends over the entire year the better will a locality 

 be adapted for rubber culture; regions with a long, absolutely dry season are unsuit- 

 able for this culture. In the valley of San Carlos, Costa Rica, upon the Atlantic 

 slope, it rains occasionally also in the dry season, and even in the two driest months, 

 March and April. The Pacific slope of Central America has, on the contrary, a 

 completely dry season of four months, and two months at the beginning and end 

 with little rain. Both the wild and the planted rubber trees die there at the third 

 tapping at the latest, in case this takes place in the dry season. a 



If the above statement represents a general fact in Costa Rica it 

 can only be said at present that either the climate, or the rubber trees, 

 or both, are different from those of southern Mexico, In spite of six 

 months of dry weather the rubber trees at La Zacualpa have reached 

 maturity in the open sun, and have survived many and severe tappings, 

 as shown in the accompanying illustrations (Plates I, XII, and XVI). 



It may not be without significance that the conditions with which 

 Herr Koschny is most familiar and which he considers favorable for 

 rubber production are not those of continuous humidit}^, for there is 

 a dry season of two or three months. In eastern Guatemala, an inter- 

 esting example of the rapidity with which the tropical sun can dry 

 out the vegetation was observed. Our party arrived at Panzos during 

 a heav}^ rain, and rode the next day toward Senahu over muddy roads 

 through the dripping leaves of a luxuriant tropical growth. Three 

 weeks later the same region was dry and parched, and even the leaves 

 of the undergrowth of the forest were shriveled. 



CASTILLA ON THE ISTHMUS OF PANAMA. 



The idea that the Castilla sent from the Isthmus of Panama to Brit- 

 ish India came from a continuously humid district seems not to be 

 justified by the statements of Mr. Cross, who secured seeds and cut- 

 tings in the vicinity of Colon. He says: 



The interior of the Darien forests would frighten most people. The undergrowth 

 is composed of boundless thickets of a prickly leaved species of Bromelia often 8 to 

 10 feet high, the ground swarms with millions of ants, and the snakes raise them- 

 selves to strike at anyone who approaches. 



The Caucho tree grows not in inundated lands or marshes, but in moist, undulating, 

 or flat situations, often by the banks of streamlets and on hillsides and summits 

 where is any loose stone and a little soil. It is adapted for the hottest parts of 

 India, where the temperature does not fall much below 74° F. The tree is of 

 rapid growth, and attains to a great size, and I am convinced that, when culti- 

 vated in India, it will answer the most sanguine expectations that may have been 

 formed concerning it. I have been up the Chagres and Gatun rivers. I came out 

 on the railway about 7 miles from Colon. I go back to the same place (the village of 

 Gatun) , from which place by the river the India-rubber forests are reached. & 



The undergrowth of Bromelia indicates a relative^ barren, open 

 forest with a severe dry season, and this supposition is strengthened 

 hy the allusion to the ants, snakes, "loose stones," and ''little soil." 



«Beihefte zum Tropenpflanzer, 2:119, 1901. 

 t> Trans. Linn. Soc, London, 2d ser., 2:213. 



