MISCELLANEOUS FIELD NOTES. 25 



Along the channels made by tapping it crumbles or easily separates. Externally it 

 is smooth and has a reddish shimmer, especially on the branches and young trees. 

 In contrast with that of the previous species it does not become fissured lengthwise, 

 but is separated into transverse bands by shallow grooves. The bands, in turn, are 

 beset with small reddish warts arranged in vertical and horizontal rows. Neverthe- 

 less, with the exception of the warts, the surface of the bark is quite smooth, with- 

 out fissures of any kind. This species occurs frequently mixed with the others, 

 usually less abundant than the white, but sometimes predominates. It may be that 

 this is the cause of the poor results attained in the experimental gardens of Java and 

 Ceylon, and that these were the more unpromising because this species requires to 

 be shaded more than the white, but was probably planted in the open. 



Costilla tana, or hule tanu, is also called "gutta-percha" by the rubber gatherers. 

 The bark is grayer but otherwise is very similar to that of the white Castilla, with 

 which the leaves and habits also agree. The species is to be distinguished principally 

 by the more prominent root folds or buttresses of the base of the trunk, which are 

 distinctly thinner than with the other species; the upper edge is also thinner and 

 sharper. This species does not occur in the San Carlos Valley, but first appears in 

 the neighborhood of Bluefields on the Mosquito coast. On the Pacific coast it is in 

 places very common. The milk flows in abundance, but becomes hard and resinous 

 on drying. Although of no use as an elastic rubber it is possible that it might be 

 adapted to some purpose, especially after the separation of the resinous constituents. 



These summaries of Koschny's descriptions include all the distinctive 

 points mentioned by him in order to facilitate the further study of 

 the subject and also to make plain the difficulty which the planter 

 would have in securing seed of the right kind, since the seeds of the 

 different species are said by Koschny to be quite indistinguishable. 



FIELD NOTES ON CASTILLA IN GUATEMALA AND SOUTHERN MEXICO. 



Castilla probably grows wild in all the tropical forests of Guatemala, 

 with the exception of those which are too wet. It is also found at 

 considerable elevations, but the yield of rubber falls off as the altitude 

 increases. In the Coban district of Alta Vera Paz there have been 

 several experiments in rubber planting, but the altitudes are probably 

 too great, and the coffee districts too continuously humid for good 

 results; consequently rubber culture is now attracting little attention. 



In the coast belt and the valleys of the Polochic and Motagua rivers 

 several rubber-planting enterprises have been undertaken and aban- 

 doned. Only scrap rubber is obtained from either wild or cultivated 

 trees. Either the milk is not produced in the same abundance or it is 

 not held in the tree under the same pressure as in the rubber trees 

 inspected later on the Pacific side of southern Mexico. It may be 

 that two varieties of the trees differ in this respect as well as in the 

 scales of the male flowers, as described above. 



According to Hon. James C. McNally, consul-general of Guatemala, 

 the productive rubber districts of Guatemala lie in the region about 

 La Gomera, on the Pacific side near the coast. The low grade of the 

 Guatemalan rubber as it comes to the market is explained by the fact 

 that a very large proportion of it is stolen by professional rubber 



