(2) 1T8 



carry only the merest traces of moisture. Throughout most of 

 this heavily watered region, the vegetation is of the densest char- 

 acter. Allowing for the breaks caused by the streams, it might 

 be said that an arboreal animal, ascending a tree upon the An- 

 dean foothills, could pass to the Atlantic without once descending 

 to the ground. 



The species and genera of this eastern Andean region have 

 in general a very wide range. With the latitude, varies the alti- 

 tude at which they grow. As w'e pass to the cooler southern 

 region, a species or its representative creeps down upon the 

 mountain sides. Thus, the Desfontainea spinosa, Remy., which 

 I collected abundantly in northern Bolivia, gradually descends, 

 until in the neighborhood of the cape, Lieutenant Safford finds 

 it near the sea level, constituting a characteristic feature of the 

 landscape. Sometimes also, a species has its limits as to altitude 

 very narrowly and sharply defined, but will be represented at 

 successively lower elevations by other species exceedingly closely 

 related. Of this, the Cinchonas furnish us a striking example. 

 Each altitude has its own species — if species they can be called — 

 and they usually overlap to but a trifling extent. I have (in 

 two cases) looked along a mountain side where miles of Cinchona 

 Calisaya had been planted, and seen the upward limit defined to 

 within fifty feet by a line of dead or dying trees. 



In general, we are disappointed by the scarcity of fiowers as 

 compared with the abundance of plants. To this rule, trees and 

 many herbs are exceptions. But in the case of shrubs and vines, 

 of which latter there is everywhere a multitude, it is strikingly 

 true. It is probably to be accounted for by the steepness of the 

 land and a climate highly favorable for the reestablishment of de- 

 tached fragments, torn away and carried to a new position. Un- 

 able to obtain the light and air necessary for a high floral de- 

 velopment, they have learned to depend upon a less complicated 

 method. 



Turning to the western side, we find, as stated, a region in 

 which almost every condition is reversed. With more or less 

 scanty rains, strictly limited to a few months or even weeks, we 

 get a treeless and almost shrubless region, with a temperature 

 subject to very sudden and great variations. The amount of 



