Of course, he’d know soon enough. He’d see the changes — see me lose my hair, see me lose weight, hear me get up and vomit in the middle of the night, maybe . . .

Maybe even hear me cry when I thought he wasn’t around.

“How sick?” asked Ricky.

“Very sick,” I said.

He looked at me some more. I nodded: I wasn’t kidding.

“Why?” asked Ricky.

Susan and I exchanged a glance. That was the same question I’d been asking myself. “I don’t know,” I said.

“Was it something you ate?”

I shook my head.

“Were you bad?”

It was an unexpected question. I thought about it for a few moments. “No,” I said. “I don’t think so.”

We were all quiet for a time. Finally, Ricky spoke softly. “You’re not going to die, are you, Daddy?”

I’d meant to tell him the truth, unvarnished. I’d meant to level with him. But, when the moment came, I had to give him more hope than Dr. Kohl had given me.

“Maybe,” I said. Just maybe.

“But . . .” Ricky’s voice was small. “But I don’t want you to die.”

I squeezed his hand. “I don’t want to die, either, but . . . but it’s like when Mommy and I make you clean your room. Sometimes we have to do things we don’t want to do.”

“I’ll be good,” he said. “I’ll always be good, if you just don’t die.”

My heart hurt. Bargaining. One of the stages.

“I really don’t have any choice in any of this,” I said. “I wish I did, but I don’t.”

He was blinking a lot; soon the tears would come.

“I love you, Daddy.”

“And I love you, too.”

“What — what will happen to Mommy and me?”

“Don’t worry, sport. You’ll still live here. You won’t have to worry about money. There’s plenty of insurance.”

Ricky looked at me, clearly not understanding.

“Don’t die, Daddy,” he said. “Please don’t die.”

I drew him close, and Susan put her arms around both of us.

12

As much as cancer frightened me as a victim, it fascinated me as a biologist.

Proto-oncogenes — the normal genes that have the potential to trigger cancer — exist in all mammals and birds. Indeed, every proto-oncogene identified to date is present in both mammals and birds. Now, birds evolved from dinosaurs which evolved from thecodonts which evolved from primitive diapsids which evolved from captorhinomorphs, the first true reptiles. Meanwhile, mammals evolved from therapsids which evolved from pelycosaurs which evolved from primitive synapsids which also evolved from captorhinomorphs. Since captorhinomorphs, the common ancestor, date back to the Pennsylvanian, almost 300 million years ago, the shared genes must have existed at least that long (and, indeed, we’ve found cancerous fossil bones that confirm that the big C existed at least as far back as the Jurassic).

In a way, it’s not surprising that these genes are shared: proto-oncogenes are related to controlling cell division or organ growth; I suspect we’ll eventually discover that the complete suite of them is common to all vertebrates, and, indeed, possibly to all animals.

The potential for cancer, it seems, is woven into the very fabric of life.

Hollus was intrigued by cladistics the study of how shared features imply common ancestry; it was the principal tool for evolutionary studies on his world. It seemed appropriate, therefore, to show him our hadrosaurs — a clade if ever there was one.

It was Tuesday — the ROM’s slowest day — and it was almost closing time. Hollus disappeared, and I worked my way through the museum over to the Dinosaur Gallery, carrying the holoform projector in my pocket. The gallery consists of two long halls, joined at their far ends; the entrance and the exit are side by side. I went in the exit and headed down. There was no one else present; several P.A. announcements about the imminent closing had moved the patrons out. At the far end of this hall is our hadrosaur room, painted with russet and golden horizontal stripes, representing sandstone from the Alberta badlands. The room contains three terrific wall mounts. I stood in front of the middle one, a duckbill, which the placard still called Kritosaurus even though we’d known for more than a decade that it was probably really a Gryposaurus; maybe my successor would find the time and money to update the gallery’s signage. The specimen, which had been collected by Parks during the ROM’s first field season in 1918, is lovely, with the ribs still in matrix and the stiffening tendons along the tail beautifully ossified.

Hollus wavered into existence, and I started talking about how the bodies of hadrosaurs were virtually indistinguishable from each other and that only the presence or absence of cranial crests, and the shapes of those crests, made it possible to tell the different genera apart. Just as I was working up a head of steam about this, a boy, maybe twelve years old, came into the room. He entered from the opposite side I had, coming out of the dimly lit Cretaceous-seas diorama. The boy was Caucasian but had epicanthic folds and a slack jaw, and his tongue protruded a bit from his mouth. He didn’t say anything; he just kept staring at the Forhilnor.

“Hell” “oh,” said Hollus.

The boy smiled, apparently delighted to hear the alien speak. “Hello,” he said back at us, slowly and deliberately.

A breathless woman rounded the corner, joining us in the Hadrosaur room. She let out a little yelp at the sight of Hollus and hurried over to the boy, taking his soft, chubby hand. “Eddie!” she said. “I’ve been looking all over for you.” She turned to us. “I’m sorry if he was disturbing you.”

Hollus said, “He” “was” “not.”

The P.A. came on. “Ladies and gentlemen, the museum is now closed. Would all patrons please immediately go to the front exit . . .”

The woman pulled Eddie, who kept looking back over his shoulder at us, down through the rest of the Dinosaur Gallery.

Hollus turned to me. “That child was unlike any I have seen.”

“He has Down syndrome,” I said. “It retards mental and physical development.”

“What causes it?”

“The presence of an extra chromosome twenty-one; all chromosomes should come in pairs, but sometimes a third one gets mixed in.”

Hollus’s eyestalks moved. “We have a similar condition, although it is almost always screened for in the womb. In our case, a chromosome pair forms without telomeres at one end; the two strands join at that end, making a chromosome twice as long as normal. The result is a complete loss of linguistic ability, many spatial-perception difficulties, and an early death.” He paused. “Still, the resilience of life amazes me. It is remarkable that something as significant as an entire extra chromosome, or two chromosomes joining into one, does not prevent the organism from functioning.” Hollus was still looking in the direction the child had disappeared. “That boy,” he said. “Will his life be cut short, too?”

“Probably. Down syndrome has that effect.”

“That is sad,” said Hollus.

I was quiet for a time. There was a little alcove to one side of the room in which an ancient slide show was playing about how dinosaur fossils form and are excavated. I’d heard its soundtrack a million times, of course. Finally, though, it ended, and since no one had pushed the big red button to start it again, Hollus and I were alone in the silent gallery, only the skeletons for company.

“Hollus,” I said at last.

The Forhilnor turned his attention back to me. “Yes?”

“How — how long are you planning to stay here? I mean, how much longer will you need my help?”

“I am sorry,” said Hollus. “I have been inconsiderate. If I am taking up too much of your time, merely say so and I shall go.”

“No, no, no. It’s nothing like that. I’m enjoying this immensely, believe me. But . . .” I blew out air.