"Human breath wouldn't do," said Paul, "Because our breath is made of Carbon dioxide, Nitrogen and Oxygen, plus several other minor gasses. What about some human substance? Blood? I'm sorry Phillip, I was just making a suggestion."

"Blood wouldn't do," Phillip said with distaste, "It is made of several common elements, all of which are found in varying percentages everywhere in the universe. Might as well use acids, or some other chemicals. Blood isn't alive - its just a liquid that helps to keep us alive."

"What isn't?" said Paul, "We're made of the soil aren't we! That's what your Book says anyway!"

"True, but in respect of anything being distinctively different out here on the moon, there is only a simpler type of molecular chemistry here. If the moon had Earth's air, and the life of Earth here, it would not be long before the moon became another, smaller version of Earth. So there's not much difference between us being here, and us not being here."

"Point taken," said Paul, "But I still think we ought to try something like blood. Nothing ventured, nothing gained?"

"Or lost," added Ralph.

Phillip glanced at the men across the cluttered table.

"OK," he sighed, "I'll check the labs."

He got up from the table and left the room.

Base was an advanced network, despite its monotonous external appearance. In the separate buildings, each linked by safety doors at each end of the tunnels, was some of the world's most advanced equipment. There were banks of computers, set in layers, working most of the time on mineral analysis, meteorological processing, and updating of information sent from Earth. There were rows of smaller devices, used for different types of exploration, emergency gear, replacement parts for the earth-movers, and several models of lunar-suit.

Phillip went past six buildings to the refrigeration plant, and began to sort through the drawers for a crate he knew he would find there. He found it quickly, unlocked the lid, and pulled out a collection of glass bottles, each containing a different fluid, now frozen. He took the bottles to a large cabinet and placed them inside. Pressing a winking red light, he stood still for a moment while the bottles were warmed. He took the bottles out, then he placed them in stasis containers and walked back to the dining room with them.