A NATURALIST'S EXCURSION IN DOMINICA. 683 



adaptation. The leaves of the Bryophyllum appear folded in the sun, 

 spread out flat in the shade ; and the same phenomenon was observed 

 in a modified form in the very abundant Psidium Guava and some 

 other species. Other plants form close and hard cuticles which restrict 

 evaporation, and some others appear to be furnished with special water- 

 vessels in their hypodermic layers. To this class seem to belong the 

 thick-leaved calabash-trees and shore-grapes, and the creeping Com- 

 melyacecB. 



From admiring a number of highly colored flowers, our attention 

 was drawn to the modest sensitive-plant {Mimosa ^yucUca), which was 

 here growing in masses as a common weed alongside of the cultivated 

 fields. A goat was feeding along the hedge-side, and had stretched 

 out his tongue toward the delicate mimosa-leaves, but had not reached 

 them, when he suddenly drew his head back in astonishment at the 

 strange sight of an array of sharp thorns, forbidding closer approach, 

 where he had only an instant before anticipated the taste of a mouth- 

 ful of delicious foliage. The mimosa thus protects itself against the 

 unwelcome feeder upon it in the same manner as the hedgehog es- 

 capes his enemies by rolling himself up into a prickly ball. Now was 

 explained to us the observation we had made before in the countrv, of 

 islands of mimosa-plants rising untouched from the pastures in which 

 all the other plants around them had been closely eaten away. The 

 same property of withdrawing itself from unfriendly contact operates 

 to protect the mimosa against injury from wind and rain. 



As we go up the mountain-walled valley of the Roseau, in the inter- 

 vals of which cultivation still presses hard upon the primitive vegeta- 

 tion, we admire the variety and brilliancy of the extra-floral display by 

 which some of the species are made conspicuous, and which is one of 

 the marked features of the West Indian flora. Here is a begonia, with 

 rose-red peduncles ; there are some bromelias, with brightly colored 

 bracts attached to their flower-stocks. The Heliconia, or wild-banana, 

 is marked from afar off not more by its enormous leaves than by the 

 brilliant purple spathe that surrounds its unobtrusive inflorescence ; 

 and the Euphorbia heterophylla is equally distinguishable by the 

 patches of crimson on the whorl of leaves nearest to its flowers ; while 

 many other plants have their real leaves variegated with stripes or 

 spots of color. Of most graceful and noble bearing are a group of 

 tree-ferns, the unapproachable delicacy of whose leaf -carving, the re- 

 markable harmonizing of the green of their foliage with the dark 

 brown of their stems, and the perfect symmetry and pose of their 

 crowns, are worthy of and receive the highest admiration. As we con- 

 tinue the ascent, the wood becomes largely composed of the Bursera 

 gummifera, a tree of the terebinth family, the magnificent stems of 

 which are supported by wide-spreading pillar-roots and varnished with 

 the white balsam that has exuded from their bark. Moss-like plants 

 nestle under the shelter of the root-pillars, lianas climb around the 



