The form in which a commodity exists, its existence as a use-value, sets definite limits to the circulation of commodity capital C' — M'. Use-values are perishable by nature. Hence if they are not productively or individually consumed within a certain time, depending on what they are intended for, in other words, if they are not sold within a certain period, they spoil and lose with their use-value the property of being vehicles of exchange-value. The capital-value contained in them, hence also the surplus-value accrued in it, gets lost. The use-values do not remain the carriers of perennial self-expanding capital-value unless they are constantly renewed and reproduced, are replaced by new use-values of the same or of some other order. The sale of the use-values in the form of commodities, hence their entry into productive or individual consumption effected through this sale is however the ever recurring condition of their reproduction. They must change their old use-form within a definite time in order to continue their existence in a new form. Exchange-value maintains itself only by means of this constant renewal of its body. The use-values of various commodities spoil sooner or later; the interval between their production and consumption may therefore be comparatively long or short; hence they can persist without spoiling in the circulation phase C — M for a shorter or longer term in the form of commodity-capital, can endure a shorter or a longer time of circulation as commodities. The limit of the circulation time of a commodity-capital imposed by the spoiling of the body of the commodity is the absolute limit of this part of the time of circulation, or of the time of circulation of commodity-capital as such. The more perishable a commodity and the sooner after its production it must therefore be consumed and hence sold, the more restricted is its capacity for removal from its place of production, the narrower therefore is the spatial sphere of its circulation, the more localised are the markets where it can be sold. For this reason the more perishable a commodity is and the greater the absolute restriction of its time of circulation as commodity on account of its physical properties, the less is it suited to be an object of capitalist production. Such a commodity can come within its grasp only in thickly populated districts or to the extent that improved transportation eliminate distance. But the concentration of the production of any article in the hands of a few and in a populous district may create a relatively large market even for such articles as are the products of large breweries, dairies, etc.