Many persons who have had much experience in prairie traveling prefer leaving the Missouri River in March or April, and feeding grain to their animals until the new grass appears. The roads become muddy and heavy after the spring rains set in, and by starting out early the worst part of the road will be passed over before the ground becomes wet and soft. This plan, however, should never be attempted unless the animals are well supplied with grain, and kept in good condition. They will eat the old grass in the spring, but it does not, in this climate, as in Utah and New Mexico, afford them sufficient sustenance. The grass, after the 1st of May, is good and abundant upon this road as far as the South Pass, from whence there is a section of about 50 miles where it is scarce; there is also a scarcity upon the desert beyond the sink of the Humboldt. As large numbers of cattle pass over the road annually, they soon consume all the grass in these barren localities, and such as pass late in the season are likely to suffer greatly, and oftentimes perish from starvation. When I came over the road in August, 1858, I seldom found myself out of sight of dead cattle for 500 miles along the road, and this was an unusually favorable year for grass, and before the main body of animals had passed for that season. Upon the head of the Sweetwater River, and west of the South Pass, alkaline springs are met with, which are exceedingly poisonous to cattle and horses. They can readily be detected by the yellowish-red color of the grass growing around them. Animals should never be allowed to graze near them or to drink the water. ORGANIZATION OF COMPANIES. After a particular route has been selected to make the journey across the plains, and the requisite number have arrived at the eastern terminus, their first business should be to organize themselves into a company and elect a commander. The company should be of sufficient magnitude to herd and guard animals, and for protection against Indians. From 50 to 70 men, properly armed and equipped, will be enough for these purposes, and any greater number only makes the movements of the party more cumbersome and tardy. In the selection of a captain, good judgment, integrity of purpose, and practical experience are the essential requisites, and these are indispensable to the harmony and consolidation of the association. His duty should be to direct the order of march, the time of starting and halting, to select the camps, detail and give orders to guards, and, indeed, to control and superintend all the movements of the company.