682 THE POPULAR SCIENCE MONTHLY. 



are putting themselves to sleep, and folding their filaments up against 

 their petioles. 



Early in the morning we start for our first night-station, the negro 

 village of Laudat, seven miles from Roseau, in the mountains. We 

 might go on horseback, but prefer a way that will give opportunity for 

 close biological observations ; so, having a negro to carry our baggage 

 and botanical books, we start out, armed with umbrella, gun, and opera- 

 glass, with which to scan inaccessible specimens in the tree-tops, on 

 foot. As we pass through the cultivated lands, we admire the areca 

 and cocoa palms, but are disappointed with the banana-trees, whose 

 leaves have been torn to shreds by wind and rain, and find the bread- 

 trees at this season presenting but a sorry spectacle. The dark masses 

 of the mango-trees make a better impression, and it is impossible 

 to repress admiration of the calabash-trees ( Crescentia cujete), with 

 great pumpkin-fruits hanging from the tips of their slender limbs, and 

 which are devoted to such varied uses : the fruit-pulp to be made into 

 a vegetable viand ; the pumpkin-shell into vessels and dishes of every 

 sort ; and the outer bark by the West Indian orchid-growers as the 

 ground on which to cultivate their fancifully shaped floral treasures. 

 As we examine the plants by the roadside, many of them stragglers 

 from the sea-shore or from foreign parts, we are struck with the 

 variety of the provisions by which they adapt themselves to resist the 

 heat and aridity of the dry season. We have already mentioned the 

 succulent stems and the condensed surface of the beach plants, and 

 the leafless condition of the coral-tree {Erythrina), which other Legu- 

 TninoscB also assume during the heats. These and other peculiarities 

 for the same end are exhibited not in the same degree for all of the 

 sj^ecies, but with numerous individual variations according to the spe- 

 cial circumstances of each particular plant, and in such a way as to 

 demonstrate a capacity for individual adaptation. Here are, close to- 

 gether, two specimens of the Bryophyllum calycinum, one standing in 

 the open sunlight, and the other under the shadow of an acacia-tree. 

 The former plant has relatively small, thick leaves, the structure of 

 which is seen under the microscope to be close and made up of palisade- 

 like cells ; while the other one displays much thinner and more loosely 

 built leaves, exposing many times as much surface to the light as its 

 companion did. Another method of adaptation is shown in the posing 

 of the surface of the leaves parallel to the sun's rays instead of perpen- 

 dicularly to them. This position in profile sometimes occurs as a 

 peculiarity of the species ; is sometimes brought about by the version 

 or folding of the leaf -blades ; and is sometimes dependent upon peri- 

 odical movements of the leaves, which seem to be provided with par- 

 ticular organs for the purpose, according to the intensity of the light. 

 The profile position appears to be fixed in the shore-grapos, which we 

 observed on the beach, in the sapoteas, and in some other species. The 

 faculty of folding the leaves appears rather to be one of individual 



