Failing to send() 1 wei from one contract to another

Question

The following code is supposed to send 1 wei from the current contract to a newly created contract. The recipient contract gets created successfully and the sending contract has a positive balance, but the call to send() fails.

address payable this_addr = address (this);
require (this_addr.balance > 100000);

MyContract mc_new = new MyContract ();
address payable mc_new_addr = address (mc_new);
bool success = mc_new_addr.send (1);

Here is the relevant code from the contract being created. I can see that the contract never has a balance and neither recieve() nor fallback() is ever called.

contract MyContract
{
    bool receive_called;
    bool fallback_called;

    constructor () payable
    {
        receive_called = false;
        fallback_called = false;
    }

    receive () external payable
    {
        receive_called = true;
    }

    fallback () external payable
    {
        fallback_called = true;
    }
}

The transfer() function doesn't work either. What am I doing wrong?

Also, what triggers calls to receive() and fallback()? Can it only be done by using one of the assembly functions? Or is the a way to trigger these function calls in ordinary solidity?