Ahead, a patch of light poked through the trees. A path led to a small wooden cottage. Jenny and Anouk approached cautiously. A broken road sign read, Torino 10 km.
“Italy, of course.” Anouk knocked on the door.
The door opened, revealing a young woman with expressive eyebrows, elegantly coifed hair, and a long floral dress. Her smile was kind, though infinitely sad. “Buon giorno. Avete portato le uova?”
“Buon giorno,” replied Anouk, going on in Italian. She told Jenny, “Doctor Levi-Montalcini wants the egg.”
The Nobel Laureate—long before she won the prize. Jenny blinked the egg from her inventory.
“Thank you,” replied Rita Levi-Montalcini in English as she closed the door behind them. “I hope there was a rooster in the hen house, so the egg will be of use. I wish I could say ‘Welcome to Turin,’ but 1941 is not a welcoming time in Europe.” Her fingers clenched for emphasis. Now if you’ll both come this way, I have some embryos prepared.”
The chick embryos were set in a glass incubator, with two round openings for arms to manipulate while maintaining the temperature. The incubator stood on a small side table, crowded next to a Zeiss microscope and a microtome. The rest of the room contained a dining table set for four and a china closet.
Levi-Montalcini reached into the incubator and held a large magnifier above one of the culture dishes. Upon the egg yolk grew an embryo, a red disc of twining blood vessels and limb buds. “In the chick embryo, I cut out a wing bud and saw the loss of nerve growth, an experiment devised by my German friend Viktor Hamburger. Viktor thought that removing the wing bud stopped new cells from becoming nerves.” Her hands rose and fell like conducting an orchestra. “I argued that the nerve cells degenerate, in the absence of a signal—”
From outside, overhead, came a whining sound. The whine fell in pitch, like distant fireworks, ending with a muffled explosion.
The doctor’s eyes flew open. “Extinguish your torch,” she hissed. “And crawl under the table.” Grabbing the Zeiss microscope, she cradled it protectively and climbed under the dining table.
The torch would not go out; Jenny fumbled, fearing to burn herself or set the cottage on fire.
Anouk whispered, “Return it to your inventory.”
With a wink the torch vanished, and Jenny joined them under the table. Another descending whine, and an explosion shook the floor. The explosions continued, growing in intensity and tumbling one upon another. She froze in panic, trapped like the ultra in the tree. A final explosion deafened her; it must surely have destroyed the house. But afterward, all was still.
“As non-Aryans,” Levi-Montalcini explained under the table, “we had to hide in the country to pursue our work. Here, I found the first clues for a signal to grow nerves. Nerve growth factor.”
Her eyes widened at Jenny, scrunched by the table leg. “Nerve growth factor grows, when your life changes. For instance, when you fall in love.”
Startled, Jenny looked away.
Rita Levi-Montalcini climbed nimbly out from the table, helping the two students up. “After the war, Viktor invited me to your country, the University of Washington, St. Louis.”
Light flooded the room, which was now a comfortable laboratory with several microscopes and incubators. Outside the window, a bell rang twice. In the city street a trolley car rolled by, while men in top hats and women in long dresses strolled the sidewalk. Levi-Montalcini now had lines in her forehead, and she wore a lace blouse with pearls.
“In St. Louis, we began our experiments to isolate the mystery signal that made nerves grow.” She gave Jenny and Anouk a closer look at the chick embryos, each with a head, a long curving backbone, and limb buds, all pulsing with new blood vessels.
Out of the corner of her eye, Jenny saw something move. A large black handbag sat by the incubator. She couldn’t help notice that the handbag was moving and stretching; something was happening inside.
“We asked: Can a foreign tissue producing the right signal make a nerve grow?” The doctor drew out a set of slides and placed the first one under a microscope. “I used my new technique of silver staining to mark nerve axons in the chick embryo. In this embryo, I implanted a source of the signal: a mouse tumor.”
“A mouse tumor in a chick embryo?” wondered Jenny.
Anouk shrugged. “Mouse and chick DNA are two-thirds the same.”
“I learned that much later,” observed the doctor, “though in retrospect, I’m not surprised. Tell me: What do you see in this embryo?”
A tangle of nerves blackened by silver grew everywhere. Jenny could scarcely make sense of it. She and Anouk took turns at the microscope.
“Any nerves in the mouse tumor?” hinted the doctor.
“Not in the tumor,” said Jenny. “But here, in the chick veins just outside the tumor, there are lots of new nerves.” Bundles of axons, creeping out from the neurons. “Where you wouldn’t expect nerves to be.”
“Excellent,” observed the doctor. “The nerves grew. But what signal caused this growth? I had to isolate the signal from mouse tumors.” She opened her handbag. Out of the handbag crept two white mice. The mice sniffed the edge of the bag and cast their noses this way and that as if discovering a new world. Each mouse had a large misshapen lump on its back.
Levi-Montalcini pointed to each tumor. “Extracts of these tumors contain a signal that makes nerves grow.” In each dish treated with the tumor extract, a black halo of nerves surrounded each chick neuron cluster.
Anouk said, “The replicates look good. But where’s the control?”
“The control— good question.” Levi-Montalcini produced several more dishes. “Instead of a tumor, this embryo was treated with a control: plain snake venom.”
Levi-Montalcini withdrew a snake from a nearby terrarium. To her horror, Jenny saw it was a rattlesnake. With gloved hands, Levi-Montalcini held the snake’s head at a covered beaker. The head lunged, its fangs struck the cover, squirting venom through.
“It’s just a control,” Levi-Montalcini assured her. “Snake venom has an enzyme we use to degrade contaminants. It’s always around the lab; a good control. Compare the tumor-treated embryos with these controls, treated only with snake venom.”
They observed one dish after another. Anouk concluded, “The tumor works best, but the venom controls all grew some nerves.”
“Precisely. Even snake venom contains this nerve growth factor. Many kinds of tissue need nerves, do they not?”
The doctor rose and checked her watch. “I wish you could stay, but at last I came back to Rome, where I was named Senator for Life. The assembly is about to open.”