We have seen in Book II [English edition: Vol. II, Part III. — Ed.] that once commodities have been converted into money, or sold, a certain portion of this money must be reconverted into the material elements of constant capital, and in the proportions required by the technical nature of the particular sphere of production. In this respect, the most important element in all branches — aside from wages, i. e., variable capital — is raw material, including auxiliary material, which is particularly important in such lines of production as do not involve raw materials in the strict sense of the term, for instance in mining and the extractive industries in general. That portion of the price which is to make good the wear and tear of machinery enters the accounts chiefly nominally so long as the machinery is at all in an operating condition. It does not greatly matter whether it is paid for and replaced by money one day or the next, or at any other stage of the period of turnover of the capital. It is quite different in the case of the raw material. If the price of raw material rises, it may be impossible to make it good fully out of the price of the commodities after wages are deducted. Violent price fluctuations therefore cause interruptions, great collisions, even catastrophes, in the process of reproduction. It is especially agricultural produce proper, i. e., raw materials taken from organic nature, which — leaving p118aside the credit system for the present — is subject to such fluctuations of value in consequence of changing yields, etc. Due to uncontrollable natural conditions, favourable or unfavourable seasons, etc., the same quantity of labour may be represented in very different quantities of use-values, and a definite quantity of these use-values may therefore have very different prices. If the value x is represented by 100 lbs of the commodity a, then the price of one lb. of a = x/100; if it is represented by 1,000 lbs of a, the price of one lb. of a = x/1,000, etc. This is therefore one of the elements of these fluctuations in the price of raw materials. A second element, mentioned at this point only for the sake of completeness — since competition and the credit system are still outside the scope of our analysis — is this: It is, in the nature of things that vegetable and animal substances whose growth and production are subject to certain organic laws and bound up with definite natural time periods, cannot be suddenly augmented in the same degree as, for instance, machines and other fixed capital, or coal, ore, etc., whose reproduction can, provided the natural conditions do not change, be rapidly accomplished in an industrially developed country. It is therefore quite possible, and under a developed system of capitalist production even inevitable, that the production and increase of the portion of constant capital consisting of fixed capital, machinery, etc., should considerably outstrip the portion consisting of organic raw materials, so that demand for the latter grows more rapidly than their supply, causing their price to rise. Rising prices actually cause 1) these raw materials to be shipped from greater distances, since the mounting prices suffice to cover greater freight rates; 2) an increase in their production, which circumstance, however, will probably not, for natural reasons, multiply the quantity of products until the following year; 3) the use of various previously unused substitutes and greater utilisation of waste. When this rise of prices begins to exert a marked influence on production and supply it indicates in most cases that the turning point has been reached at which demand drops on account of the protracted rise in the price of the raw material and of all commodities of which it is an element, causing a reaction in the price of raw material. Aside from the convulsions which this causes in various forms through depreciation of capital, there are also other circumstances, which we shall mention shortly.