(Describer) Streams of light collide to create a globe filled with water. Title: Science Nation.

(Describer) In a spider web, spokes of silk extend from the center with other threads connecting them.

(male narrator) This is a story about silk and milk. The silk is from golden orb weaver spiders.

(female) Here you go, pumpkin. They're inquisitive and really fun.

(narrator) The milk, from specially bred goats. Good luck trying to connect those dots. So what's the thread? There's lots of interest in spider silk fibers.

(Describer) Randy Lewis:

They're elastic and stronger than almost all manmade fibers.

(narrator) Because it's stronger ounce-for-ounce than other materials, there are many possible medical uses, from artificial ligaments to sutures for surgery. How do you produce large amounts of the material?

(narrator) Spider farms don't work. They tend to kill each other. So molecular biologist Randy Lewis figured out how to put the spiders' silk-making genes into goats.

(Randy Lewis) We put that gene into goats, so they'd only make the protein in their milk. When they have kids and start lactating, collect the milk, and we can purify that protein in much higher quantities.

(narrator) With help from the National Science Foundation...

[bleats]

Lewis studies spider silk at the University of Wyoming. He's seen no differences in the health or appearance of the transgenic goats. Good girl. Come on.

(Describer) He tries to lift one from a platform, but it steps down on its own.

I know, you don't want to go down.

(narrator) Feeding and milking goats and wrangling spiders are sometimes part of the job. We collect the milk here, then we process it in the lab.

(Describer) It's pumped into a canister.

(Describer) Holding a spider...

The silk we're curious about is the dragline.

(Describer) Heather Rothfuss:

That's the web's outside and the strongest part.

(narrator) Chemical engineer Heather Rothfuss separates the silk protein from the milk. No arachnophobia for her. In fact, she's actually warmed up to working with spiders.

(Describer) Threads wind around a turning cylinder.

I'm on the roll now. It's collecting okay.

(narrator) Just four drops of protein processed from the milk can spin four yards of silk.

(Lewis) There will be many applications--

(Describer) Lewis:

eye surgery, plastic surgery, neurosurgery.

(narrator) The lab is also introducing genes into alfalfa plants. How do people react to this tangled web of a tale?

(Lewis) They understand you can't farm spiders. You need another way of developing material.

(narrator) No kidding. For Science Nation, I'm Miles O' Brien.