Lawton shook his head. "It isn't at all, sir. We've had it drummed into us that evolution proceeds at a snailish pace, but what proof have we that it can't mutate with lightning-like rapidity? I've told you there are gases outside we can't even make in a chemical laboratory, molecular arrangements that are alien to earth."
"But plants derive nourishment from the soil," interpolated Forrester.
"I know. But if there are alien gases in the air the surface of the bubble must be reeking with unheard of chemicals. There may be compounds inside the bubble which have so sped up organic processes that a hundred million year cycle of mutations has been telescoped into an hour."
Lawton was pacing the floor again. "It would be simpler to assume that seeds of existing plants became somehow caught up and imprisoned in the bubble. But the plants around us never existed on earth. I'm no botanist, but I know what the Congo has on tap, and the great rain forests of the Amazon."
"Dave, if the growth continues it will fill the bubble. It will choke off all our air."
"Don't you suppose I realize that? We've got to destroy that growth before it destroys us."
It was pitiful to watch the crew's morale sag. The miasmal taint of the ominously proliferating vegetation was soon pervading the ship, spreading demoralization everywhere.
It was particularly awful straight down. Above a ropy tangle of livid vines and creepers a kingly stench weed towered, purplish and bloated and weighted down with seed pods.
It seemed sentient, somehow. It was growing so fast that the evil odor which poured from it could be correlated with the increase of tension inside the ship. From that particular plant, minute by slow minute, there surged a continuously mounting offensiveness, like nothing Lawton had ever smelt before.