It is constantly asserted that white men can not labor in the tropics, which we may freely admit; but the inference that the climate of the Southern States is tropical we have the best authority for denying: firstly, from the testimony of all Southern writers when describing their own section of country, and _not_ arguing upon the slavery question; and, secondly, from Humboldt's isothermal lines, by which we find that the temperature of the cotton States is the same as that of Portugal, the south of Spain, Italy, and Australia. Do we find Australian emigrants writing home to their friends not to come out because they will not be able to work? We know they do not; and yet the mean annual temperature of Australia is 70°--greater by five to six degrees than that of Texas; and, from the best accounts we can get, the extreme of heat is very much greater. Examine De Bow's analysis of the census of 1850, and we find him compelled to admit that one-ninth of the force then cultivating cotton were white men. If one-ninth were white men in 1850, when the price of cotton was much less and the crop much smaller than of late years, how many are there now? One of the most reliable witnesses to the cultivation of cotton by free labor is a Quaker gentleman in Philadelphia, who conducts a cotton factory supplied entirely with free-grown cotton, the goods being sold to the Quakers, who will not use the product of slave labor of any kind. This gentleman writes:-- I learned by correspondence with several intelligent Germans in Texas, that their experiment of raising cotton by their own labor, without the help of slaves, was a complete success. One planter offered to supply me at once with one hundred and forty bales raised in this way. The ground taken by thee that cotton can be raised by white men, as well as by colored men, is entirely correct. A very large portion is every year so raised. I have had particular information of its being thus raised in Texas, Arkansas, Tennessee, Mississippi, Alabama, Georgia, and North Carolina. In some neighborhoods thousands of bales are thus raised within the limits of two or three adjacent counties. It may be urged that this is upon uplands almost exclusively, and that upon bottom lands it is not possible, on account of their being unhealthy. Two statements will be made to disprove this latter assertion, and we will then admit it to be true, and prove it to be of no consequence. The cotton planters, deserting the rolling land, are fast pouring in upon the 'swamp.' Indeed, the impression of the sickliness of the South generally has been rapidly losing ground (i.e. among the whites of the South), and that blessing, health, is now sought with as much confidence on the swamp lands of the Yazoo and the Mississippi, as among the hills and plains of Carolina and Virginia.--_De Bow's Resources of the South and West_.