282 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 



might easily be extended and with a more thorough study might 

 furnish an interesting question as to the rapidity of muhiplication of 

 these plants and as to the means by which they hold their own among 

 the more rapidly multiplying plants. As to the question why certain 

 plants are found on one slope and not on another, the palms as an 

 example may explain. At an altitude of 500 or more meters, palms 

 of various kinds are scattered about among the other forest vegetation. 

 This occurs, however, only on slopes to the northeast, that is, exposed 

 to the northeast trades. The opposite sides at this high altitude 

 present an ordinary forest front undotted by a single palm. Moisture, 

 then, either by its immediate presence or in its relation to the winds 

 very probably is a factor in the distribution of all the plants. 



So far as methods of distribution are concerned it may be said that 

 there are very few special adaptations to dispersal. Cenchrus echinatus 

 seems to be the only one adapted for dispersal by means of its prickly 

 fruit, which adheres to animals. The various members of the Bigno- 

 niaceae and of the Asclepiadaceae are suited for wind dispersion as 

 are also Goss\"pium and Botabax. Of course there is no limit to the 

 carrjing of seeds by birds from one valley to another so that the 

 absence or presence of moisture is probably the most potent factor 

 restricting the mountain plants to the mountain and the lowland 

 plants to the lowlands. 



The further question as to the distribution of the plants according 

 to season is quite as interesting as the distribution of the plants in the 

 various topographical regions. There is a striking difference in the 

 appearance of the plains, the hills, and the valleys as seen in the rainy 

 season and in the dry. In the rainy period the fields are carpeted with 

 green and the bushes and trees are heavy with foliage and bright with 

 blossoms. In the dry season the fields are almost devoid of stick or 

 leaf and many bushes and trees are to every appearance dead. When 

 the rains come on in July or August, Tribulus ierresiris and Kalstroe- 

 mia maxima cover the roadsides and plains; Stack y tar pheta coccinea 

 and S. jamaicensis, Sperviacoce tenuior, Argemone inexicana, Asclepias 

 curassavica, and many others form a rank growth of weeds in the 

 coconut groves and cane fields ; various shrubs of the hillside, Capparis 

 verrucosa, Cassia cmarginata, Bauhinia cumanensis, and others are 

 out in leaf and in flower; and the climbing shrubs and vines form a 

 luxuriant growth along the "rio" beds. In the dry season only a few 

 of these plants can be found in flower. It is noteworthy that in several 



