does M become M´?
Answer. There is NO WAY that M can become M´!
Where is the solution?
Just recall what Keynes (1937) said: "If investment is proceeding at a steady rate, the finance ... required can be supplied from a revolving fund of a more or less constant amount."
With that in mind, just put the question like this:
Why does it look like, that M becomes M´?
As the old Greeks teached us: with the correct question the answer is contained in it.
But to elaborate the answer, we have to go through several concepts of economic reasonig.