18 BOTANY OF THE ROUTE. 



dam, and, witli the immonso 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 accumulation 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 Great 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 off in twenty-four hours, and we found that south 

 nf the Spokane river it had been replaced by rain.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 groiving 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 worst period of the year for that purpose. Yet in the 

 small collection of eighty species of plants there are two new ones, {Astragalus seratimis and 

 3Ialacotiirix crepokles,) 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, (Podiceps occidentalis,) 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. 



EEGION WEST OF 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 descrijation 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 



