DOCTOR: Finding the macro world difficult? It flies away from the base. It is time for the spawning. It's on its way to Titan to breed. The Doctor zips speedily into the TARDIS and slams the door, getting the end of the scarf caught. [SCENE_BREAK]
Inside the TARDIS Leela and K9 come in.
Plan: A: the clones; Q: What is the alien virus trying to retrieve? A: the alien virus; Q: What is brought from the microbial world into the macro world? Summary: In trying to retrieve the clones from inside the Doctor, the alien virus is brought from the microbial world into the macro-world, and it's ready to spawn.