Charles
What Marx wrote just before the passage you quote is the following:
"Direct barter, the spontaneous form of exchange, signifies the beginning of the transformation of use-values into commodities rather than the transformation of commodities into money. Exchange-value does not acquire an independent form, but is still directly tied to use-value. . . . In fact, the exchange of commodities evolves originally not within primitive communities, [11] but on their margins, on their borders, the few points where they come into contact with other communities. This is where barter begins and moves thence into the interior of the community, exerting a disintegrating influence upon it. The particular use-values which, as a result of barter between different communities, become commodities, e.g., slaves, cattle, metals, usually serve also as the first money within these communities. . . . The gradual extension of barter, the growing number of exchange transactions, and the increasing variety of commodities bartered lead, therefore, to the further development of the commodity as exchange- value, stimulates the formation of money and consequently has a disintegrating effect on direct barter."
http://www.marxists.org/archive/marx/works/1859/critique-pol-economy/ch01.htm