14 
THE BOTANY OF THE ROUTE. 
partially form a dam, and, with the immense and inexhaustible timber on the mountains, can be 
made to retain a supply of water both for this purpose and to assist in navigation in the mode 
suggested by Mr. Ellet, in the Smithsonian Contributions, for improving the navigation of the 
Ohio. The natural accumlation of alluvial soil in the lowest places would, without doubt, make 
the banks of this river the most fertile instead of the most barren of all, were it not for the 
extreme dryness of the climate. Like the rich valley of the Nile, it may, by irrigation, hereafter 
support a population as great and flourishing as that of Egypt in her palmiest days. It has also 
the advantage that the worst land of the G-reat Plain is far superior to the deserts which border 
the Nile valley. In the chapter on the climate of the country along the route this question of 
cultivation will be found more fully discussed, and compared with other countries. 
The relations of climate to the natural productions of the central division of the Territory are 
very interesting, and although the data are still incomplete, they show that moisture must be 
the only thing wanting to produce a luxuriant vegetation. 
There being little rain, of course snows must be light, but, north of latitude 48°, begin early 
and cover the ground throughout winter, forming an excellent protection for winter grains, 
besides advantages for travelling, and do not become so deep as to prevent grazing. While at 
Fort Colville, as early as October 24, we had a fall of about six inches of snow, almost the first 
storm of the season. This, however, melted oft' in twenty -four hours, and Ave found that south 
of the Spokane river it had been replaced by rain. After October 1 there is a fall growth of 
grass, especially where the surface has been burnt over, and we found the hills near the 
Okonagan, in October and near the Walla-Walla in November, covered with the richest green 
herbage. As early as February 19, 1854, Lieutenant Grover found the grass " springing up 
plentifully" on the Spokane plain, while the forests he had just left north and east of that 
river were still obstructed by deep snows. The growing season begins and ends early, 
extending from about March 1 to June, like that of the fertile valleys of California. 
The time during which I collected on the central plains of the Territory, extending from 
August 16 to November 17, was the woi'st period of the year for that purpose. Yet in the 
small collection of eighty species of plants there are two new ones, ( Astragalus seratinus and 
31alacothrix crepoidesj besides several others of interest, showing that at more favorable 
seasons the botanist may still obtain novelties in a field already more explored than any other 
west of the Rocky mountains. Among mammals, all kinds of which were scarce, I can only 
mention one as new, ( Hesperomys austerus.) Of birds, one is new, fFodiceps occidentalis, J 
others scarcely before known, (Picus alpolarvatus, Sittapygmaea^ ) although I never saw a 
region so poor in these animals during summer. After October the fall migration began to 
bring southward many interesting species, which our rapid travelling during the short days did 
not allow me time to collect. 
Dr. Le Conte has found several new insects among those obtained there, and the few reptiles 
and fish I succeeded in preserving furnish several new and interesting species. 
KEGION WEST OP THE CASCADE MOUNTAINS. 
I now return to the western region of the Territory, including the entire surface west of the 
Cascade range, which I have left for the last description because it occupies the lowest portions 
of the Territory, and because my residence in it of two years gives me the means of describing 
it the most fully. Occasional extracts from my journal may show its striking peculiarities in a 
stronger light than mere methodical description alone. In descending the Columbia from the 
