40 
International Excursion in America . 
According to Professor Clements it is preceded in succession on the 
one hand by alpine gravel-slide, on the other by alpine bog. The 
top of Pike’s Peak itself is covered with “ mountain-top detritus,” 
holding a very scanty vegetation. The snow-line is of course well 
above the summit in this latitude with so low a precipitation—about 
28 inches on the summit. There are two or three tiny glaciers in 
the neighbourhood of Long’s Peak, 100 miles to the north. 
A feature of the stay at Minnehaha was discussion on vegetation 
concepts : in particular a discussion in which the divergent views of 
the plant-formation were made very clear. Of the two main 
conceptions, one started with the formation as a purely local 
phenomenon, with a specific floristic composition, recognising 
analogies between any given formation and others with similar 
growth-forms in other parts of the world; the other considered a 
formation as a universal phenomenon with the same fundamental 
relations to environment wherever it occurs and represented in 
different places by communities of different floristic composition. 
To the acceptance ol such a concept the adherents of the former 
view objected that we have not as yet enough accurate comparative 
knowledge of analogous plant-communities in different parts of the 
world to predicate identity of environmental relations, in spite of 
similarity or identity of growth-form. It is safe—and very satis¬ 
factory—to say that the phytogeographers present were all in 
substantial agreement as to what they meant by a plant-association, 
and this at any rate is a very distinct first step to that general 
agreement as to vegetation concepts which must eventually come. 
On August 21st the party left their pleasant abode at Minnehaha 
and returned to Colorado Springs, where the members were most 
charmingly entertained to supper at the El Paso Club by some of 
the leading inhabitants of the city, where there is a large Anglo- 
American colony. 
On the following morning, August 22nd, the party left Colorado 
Springs for Salt Lake City by the Denver and Rio Grande railroad. 
The route at first lay southward, skirting the foothills, and traversing 
the formations previously seen. A triplex canescens and Opuntia 
arborescens are however conspicuous here in the Plains formation, 
and the sage-brush ( Artemisia tridentata) begins to appear from the 
south. At Pueblo the line turns west and beyond Canyon City enters 
the Royal Gorge of the Arkansas river, bounded in places by abrupt 
cliffs 2,000 feet high. The Pignon-Juniper association is very well 
developed on the north exposure, with Opuntia arborescens largely 
