This point is not merely an academic one. It means that we cannot explain the _relative_ prices of cotton lint and cotton-seed in terms of cost at all, whether marginal or otherwise. The influence of cost will be confined to the _sum_ of the prices of the two things. Upon this sum it will exert precisely the same influence as it exerts upon price in general, by affecting the total quantities of the two things that will be supplied. But upon the distribution of this sum between lint and seed, cost will exert no influence whatever, because it cannot affect the proportions in which they are supplied. It may assist some readers if I state the matter in more concrete terms. Cost of production will be one of the factors which will result in the production of an annual cotton crop in the United States of, let us say, 10 million tons of seed cotton. This crop will yield roughly 6-2/3 million tons of cotton-seed, and 3-1/3 million tons (or rather more than 13 million bales) of lint. The combined price received by the planter of (let us say) 14.4 cents for 1 pound of lint plus 2 pounds of seed should correspond roughly to the marginal joint costs of production. But the factor of cost has no influence at all in determining that this combined price is made up of a price of 12 cents per pound for lint, and only 1.2 cents per pound (or $24 per ton) for cotton-seed. To account for this we must rely entirely upon demand. We can say, shortly, that the respective prices must be such as will enable the demand to carry off 6-2/3 million tons of seed, and 3-1/3 million tons of raw cotton. Or we can go further and say that the marginal utility of a pound of raw cotton, when 3-1/3 million tons are supplied, is ten times as great as that of a pound of seed when 6-2/3 million tons are supplied.