What is missing and what is it for !!!

Hi fella's went to move my 110 and had no clutch.I put a new master cylinder on last week and bled the system and the clutch was fine,today however the clutch pedal just hit the floor.Checked the master cylinder and it was empty.Looked underneath and noticed clutch fluid leaking from this hole and it appears a bolt plug is missing,but I can't understand why clutch fluid is coming out,I'm a novice so can any of you more qualified members suggest what's going on and what am I missing.I appreciate any information,I'm assuming the slave cylinder is leaking into the housing but I'm not sure. [/IMG]

sorry for the large photo but wanted you to be able to see it

Bell housing drain plug...
And it isn't missing...

slave cylinders leaking ,hole doesnt need a plug unless your wading

That's the wading plug hole and doesn't need a plug unless you're heading for deep water, the fluid coming out is from the slave cylinder and you need a new one

Guess that pretty much confirms that then.....

Thank you fella's,just ordered a new slave cylinder,you lot know your stuff,your advice is much appreciated thank you