Biotech stocks plummeted last week as President Clinton and British Prime Minister Tony Blair requested that companies make their data on the human genome public.

Private firms are racing madly to read and patent the genetic code that makes you you and me me. They are trying to beat publicly funded labs, which are required as a condition of their grants to publish the gene sequences they unravel. One company, Celera Genomics, is funded by drug companies with the understanding that the funders will see the code before anyone else does.

If it strikes you as alarming that private investors can patent, keep secret, and sell something that sits within every cell of your body, you ought to pay much closer attention to the new, jaw-dropping biotech industry. I have just spent several weeks with my students listening to biotech enthusiasts, critics, and a lot of folks in between. There were three particular moments I’d like to tell you about, all of them moments of stunned silence.

The first came when we heard from an ecologist who sits on a USDA panel that approves the release of genetically engineered crop plants. Of the 71 applications currently pending, one is for the implantation of the gene by which scorpions make their toxin. Splice that gene into a plant, and anything that nibbles on a leaf, from woodchucks to bugs, falls down dead. Of course people who eat the plant fall down dead too, so there must also be a package of genes to turn the scorpion gene on and off. Turn it on in the roots and leaves and stems, turn it off in the flower and fruit.

But what happens to the poison, the students asked, when roots or leaves decompose in the soil? What happens if the turn-off gene doesn’t work infallibly? Would we have to check every fruit or grain for traces of scorpion poison?

“Don’t know,” said the ecologist.

Silence.

The second moment came when a geneticist described a new rice with a pasted-in gene that allows the plant to make and store beta-carotene, the yellow pigment from which our bodies make vitamin A. Thousands of poor children in Asia, who eat little but rice, go blind or die for lack of vitamin A. The “golden rice” could solve that problem.

A hand went up, and one of the students asked, “Why not just splice the beta-carotene gene into the child?”

Silence. Finally another visiting expert said, “Within five years that could be possible. Fasten your seat belts.”

More silence. I guess everyone’s mind was racing as mine was. I was picturing golden children. Then I thought, why not splice in the gene for chlorophyll while we’re at it, and just send the kids out in the sun to photosynthesize their lunch? Gold-green children.

Moment number three came when I showed the students a documentary called The Day After Trinity. It’s the story of J. Robert Oppenheimer, the developer of the atomic bomb, told through interviews with some of the great physicists who worked with him at Los Alamos during the Second World War.

The cause was compelling: to stop Hitler. The science was thrilling. The effort was tremendous. The bomb was nearing completion when Hitler surrendered in May, 1945.

That surrender did not cause any slowdown in the work at Los Alamos. There was too much excitement. It was nearly time for the first test, called Trinity, which took place at Alamagordo, N.M., on July 16. The scientists said that on that day, as they watched the first atom bomb explosion in history, their reaction was joyous. “It worked!”

Less than a month later, when a similar bomb incinerated 100,000 people at Hiroshima, one scientist said his first thought was, “Thank goodness it wasn’t a dud.” His second thought was, “Oh my God, what have we done?”

The film ends with Oppenheimer testifying in Washington two decades later. When asked by a senator how to contain the nuclear arms race, Oppenheimer answered, “It’s 20 years too late. We should have done it the day after Trinity.”

I turned on the lights. The students just sat there. Didn’t move. Didn’t say a word. I couldn’t either.

Geneticists are already cloning sheep and cows and mice and pigs. They can pick out a trait from almost any creature and paste it into any other, and they are on the verge of being able to turn a gene on or off at will. We already plant gene-spliced crops on tens of millions of acres. We can order genes from catalogs. Within a few years we will be able to read the code for our very selves and reach in and tinker with it. It is only a matter of time before hackers appear who think it might be fun, as computer hackers do, to create and release their own viruses.

The stock market is speculating on this stuff. National leaders ask companies, politely, to make their knowledge available to all. We need to do much more than that, more than just fasten our seatbelts and go along for the ride. We need to slow down and think together about where this technology is going and who should own it and who should make these decisions.

For genomics it is still the day after Trinity. We don’t want or need to have to ask, helplessly, “Oh my God, what have we done?”