The value of the constant capital is not created in this production process.
The value it transfers to the commodity then reappears in the commodity-value, and so enables it to be replaced.
“This element of the cost-price, therefore, has a double meaning. On the one hand, it goes into the cost-price of the commodity, because it is part of the commodity-value which replaces consumed capital. And on the other hand, it forms an element of the commodity-value only because it is the value of expended capital or because the means of production cost so and so much.” (p 29)
But, the opposite is true with the variable capital. The 200 hours spent in the production process creates £200 of new value. £100 of that goes to reproduce the variable capital advanced, and the other £100 as surplus value.
“But this advanced capital-value does not in any way go into the creation of the new value. So far as the advance of capital is concerned, labour-power counts as a value. But in the process of production it acts as the creator of value. The place of the value of the labour-power that obtains within the advanced capital is taken in the actually functioning productive capital by living value-creating labour-power itself.” (p 29)
In other words, it is not the commodity labour-power that is transferred to the end product, in the way that the commodity cotton is transferred to yarn. The commodity labour-power is what the name suggests, the power to undertake value-creating labour. This power is in no way transferred to the end commodity. Even where the worker's end product is a machine, that might replace the labour of other workers, he doesn't transfer his power of undertaking value creating labour. The machine can do work, but not labour, and certainly not value creating labour. The machine itself will only be able to transfer its own value not create new value.
It is not the value of the commodity labour-power that is transferred to the new product. The new value added to that product is the consequence, the creation of new value by the act of labour itself. The consequence of this can readily be seen if we look at what happens, as a consequence of a change in the value of the constant capital, as opposed to the variable capital.
We started with:-
£400 c + £100 v + £100 s = £600.
This is what happens if the value of the constant capital changes.
£300 c + £100 v + £100 s = £500
£500 c + £100 v + £100 s = £700.
In neither case does it affect the surplus value, because the amount of new value created in the production process has not changed. Two hundred hours are still expended, so the £200 of new value is created, divided as before. But, in the first case, the lower value of c causes the value of the end product to fall, because this lower value is transferred to it. In the second case, the value of the end product rises for the same reason.
But, if the value of the variable capital changes.
£400 c + £150 v + £50 s = £600
£400 c + £50 v + £150 s = £600.
Here it is the value of the end product that does not change. The value of the constant capital transferred to it has not changed. But, also, the new value created, in the production process, has not changed. It remains at 200 hours undertaken creating £200 of new value. All that changes is its division. In the first case, the value of labour-power has risen by 50% meaning the equivalent of 150 hours of labour are required for its reproduction. The variable capital advanced reflects this, so that out of the £200 of new value created, only £50 are now left over as surplus value. In the second case, the value of labour-power has fallen so that only 50 hours are required for its reproduction. Consequently, surplus value rises to £150.
The difference is precisely because the constant capital transfers its own value to the commodity, but the variable capital does not. But, under capitalist production things seem reversed. The value of labour-power appears, in the form of wages, rather as the price of labour itself.
“The variable part of the advanced capital, therefore, appears as capital expended in wages, as a capital-value which pays for the value, and accordingly the price, of all the labour expended in production.” (p 30)
The value of the labour-power bought is £100, which is the equivalent of 100 days of labour. That is how much labour needs to be expended to produce the commodities required to reproduce that labour-power, and which are bought by the workers with their wages. But, the labour performed by the workers is 200 days, and their wages appear as 200 days of labour. The labour performed of 200 days thereby adds 200 days of new value, equal to £200. If we divide the workers wages of £100 by the number of days labour they perform, which is 200, we get a daily wage of £0.50, although the value produced by a day's labour we know is £1.