“Reducing the number of revolutions per minute，” Mr. Foster explained. “The surrogate goes round slower； therefore passes through the lung at longer intervals； therefore gives the embryo less oxygen. Nothing like oxygen-shortage for keeping an embryo below par.” Again he rubbed his hands.
“But why do you want to keep the embryo below par？” asked an ingenuous student.
“Ass！” said the Director， breaking a long silence. “Hasn’t it occurred to you that an Epsilon embryo must have an Epsilon environment as well as an Epsilon heredity？”
It evidently hadn’t occurred to him. He was covered with confusion.
“The lower the caste，” said Mr. Foster， “the shorter the oxygen.” The first organ affected was the brain. After that the skeleton. At seventy per cent of normal oxygen you got dwarfs. At less than seventy eyeless monsters.
“Who are no use at all，” concluded Mr. Foster.
Whereas （his voice became confidential and eager）， if they could discover a technique for shortening the period of maturation what a triumph， what a benefaction to Society！
“Consider the horse.”
They considered it.
Mature at six； the elephant at ten. While at thirteen a man is not yet sexually mature； and is only full-grown at twenty. Hence， of course， that fruit of delayed development， the human intelligence.
“But in Epsilons，” said Mr. Foster very justly， “we don’t need human intelligence.”
Didn’t need and didn’t get it. But though the Epsilon mind was mature at ten， the Epsilon body was not fit to work till eighteen. Long years of superfluous and wasted immaturity. If the physical development could be speeded up till it was as quick， say， as a cow’s， what an enormous saving to the Community！
“Enormous！” murmured the students. Mr. Foster’s enthusiasm was infectious.
He became rather technical； spoke of the abnormal endocrine co-ordination which made men grow so slowly； postulated a germinal mutation to account for it. Could the effects of this germinal mutation be undone？ Could the individual Epsilon embryo be made a revert， by a suitable technique， to the normality of dogs and cows？ That was the problem. And it was all but solved.
Pilkington， at Mombasa， had produced individuals who were sexually mature at four and full-grown at six and a half. A scientific triumph. But socially useless. Six-year-old men and women were too stupid to do even Epsilon work. And the process was an all-or-nothing one； either you failed to modify at all， or else you modified the whole way. They were still trying to find the ideal compromise between adults of twenty and adults of six. So far without success. Mr. Foster sighed and shook his head.
Their wanderings through the crimson twilight had brought them to the neighborhood of Metre 170 on Rack 9. From this point onwards Rack 9 was enclosed and the bottle performed the remainder of their journey in a kind of tunnel， interrupted here and there by openings two or three metres wide.
“Heat conditioning，” said Mr. Foster.
Hot tunnels alternated with cool tunnels. Coolness was wedded to discomfort in the form of hard X-rays. By the time they were decanted the embryos had a horror of cold. They were predestined to emigrate to the tropics， to be miner and acetate silk spinners and steel workers. Later on their minds would be made to endorse the judgment of their bodies. “We condition them to thrive on heat，” concluded Mr. Foster. “Our colleagues upstairs will teach them to love it.”
“And that，” put in the Director sententiously， “that is the secret of happiness and virtue–liking what you’ve got to do. All conditioning aims at that： making people like their unescapable social destiny.”
In a gap between two tunnels， a nurse was delicately probing with a long fine syringe into the gelatinous contents of a passing bottle. The students and their guides stood watching her for a few moments in silence.
“Well， Lenina，” said Mr. Foster， when at last she withdrew the syringe and straightened herself up.
The girl turned with a start. One could see that， for all the lupus and the purple eyes， she was uncommonly pretty.
“Henry！” Her smile flashed redly at him–a row of coral teeth.
“Charming， charming，” murmured the Director and， giving her two or three little pats， received in exchange a rather deferential smile for himself.
“What are you giving them？” asked Mr. Foster， making his tone very professional.
“Oh， the usual typhoid and sleeping sickness.”
“Tropical workers start being inoculated at Metre 150，” Mr. Foster explained to the students. “The embryos still have gills. We immunize the fish against the future man’s diseases.” Then， turning back to Lenina， “Ten to five on the roof this afternoon，” he said， “as usual.”
“Charming，” said the Dhector once more， and， with a final pat， moved away after the others.
On Rack 10 rows of next generation’s chemical workers were being trained in the toleration of lead， caustic soda， tar， chlorine. The first of a batch of two hundred and fifty embryonic rocket-plane engineers was just passing the eleven hundred metre mark on Rack 3. A special mechanism kept their containers in constant rotation. “To improve their sense of balance，” Mr. Foster explained. “Doing repairs on the outside of a rocket in mid-air is a ticklish job. We slacken off the circulation when they’re right way up， so that they’re half starved， and double the flow of surrogate when they’re upside down. They learn to associate topsy-turvydom with weli-being； in fact， they’re only truly happy when they’re standing on their heads.
“And now，” Mr. Foster went on， “I’d like to show you some very interesting conditioning for Alpha Plus Intellectuals. We have a big batch of them on Rack 5. First Gallery level，” he called to two boys who had started to go down to the ground floor.
“They’re round about Metre 900，” he explained. “You can’t really do any useful intellectual conditioning till the foetuses have lost their tails. Follow me.”
But the Director had looked at his watch. “Ten to three，” he said. “No time for the intellectual embryos， I’m afraid. We must go up to the Nurseries before the children have finished their afternoon sleep.”
Mr. Foster was disappointed. “At least one glance at the Decanting Room，” he pleaded.
“Very well then.” The Director smiled indulgently. “Just one glance.”
