Descendants of the homozygous plant all appear tall, while half of the heterozygous descendants will be short. The test cross. Ressler referred to his abandoned profession by a name both sardonic and nostalgic — the irony of one no longer in the inner circle. To Frank and me, he always called geneticists soldiers of the cross.
First filial generation after Mendel had to find where these abstract inheritance packets resided. From the beginning, men hoped that genes would prove chemical, tangible. The coordinated effort reads like the greatest whodunit ever written. Blundering with desire toward fruition, as poet-scientist Goethe says. While geneticists made their gross observations, cytologists began to elucidate the microscopic ecosystem of the cell. As early as mid-nineteenth century, researchers described dark threads in the cell nucleus. Improvements in staining and microscopy revealed that the rods came in mixed doubles. During the choreography of cell division, these chromosome pairs split and moved toward opposite poles. Each daughter cell wound up with a full chromosome complement. Chromosome behavior suspiciously resembled Mendel's combining and separating pairs.
The gene factor somehow lay inside the chromosome, a segment of the thread: a tie bordering on magic. It must have been pure fear, to isolate the physical chunk embodying the ethereal plan, the seed distilling the idea of organism. The first link in the chain from Word to flesh, philosopher's stone, talisman, elixir, incantation, the old myth of knowledge incorporated in things. I can't imagine the excitement of living at the moment when the pieces began to fall into place: living design located in matter. On second thought, I can imagine. This morning's papers carried another update.
Traits didn't behave as cleanly as theory would have them. Morgan and team spent seventeen years in massive, spirit-breaking effort, counting two thousand gene factors in endless generations of Drosophila. Mendel's predicted ratios for second-generation dihybrids did not always occur. Experiment, recalcitrant, gave different numbers than pattern dictated. First temptation must have been to squash the aberrant gnats, take no prisoners. Morgan, not yet believing the chromosome theory, found that certain characteristics always occurred together. Such linkage supported the notion that groups of genes lay along shared chromosome threads. Linked traits lay on the same thread, passed through generations as a unit.
But Morgan's team also turned up incomplete linkage. Occasionally in the chaos of meiosis, paired chromosomes from separate parents cross over, break at equivalent points, and exchange parts. Half a linked group might thus be sent packing. Leverage into the unobservable: the odds of linked traits being split must vary with their distance on the chromosome. The chance of a break falling between two adjacent genes is very small, whereas any split in the chromosome separates the genes at opposite ends of a thread. Frequencies of separation thus mapped relative distance between genes.
The chemistry was still lacking. But chemistry would come. Ressler himself would join in the cartographic project of ever-improving scale. Inexorable, but full of halting dead ends, overlooked insights, reversals. Morgan's work too was resisted by the scientific community, while Levene's incorrect tetranucleotide hypothesis was embraced disastrously for years. Researchers have made every possible mistake along the way. Reject the Moravian monk; doubt Morgan; ignore Avery's 1944 identification of the genetic substance. Fits and starts, endless backtracking, limited less by technique than by the ability to conceive. How do you get moonlight into a chamber? Dress someone up as the moon.
Mendel's laws have since become more complex. Linkage, multiple alleles, epistasis, collaboration, and modifiers enhance his metaphor. But by the time Ressler took orders, neo-Mendelism was forever in place. Cyfer had inherited the idea that all of an organism's characteristics were written in a somatic language, generated by a grammar that produced outward sentences distinct but derivable from deep structure.
I live at the moment of synthesis, sense the work that is almost written, watch the structure complete its span, register for the first time how strewn with mistake and hope the path has been. This place, this night, a lamp, a typing machine, my books, my chromosomal map: I grope for my technique, my leverage into Dr. Ressler's world. The test cross that will spring the hidden, recessive gene. How he blundered with desire toward fruition. How in fruition, pining for desire.
Public Occurrences Both Foreign and Domestic
My private life began to accelerate. Before Todd, I never thought of myself as having a private life, let alone one with a brisk plot. Opening the door a crack on that stray, I found my after-hours hinting at a first etude, a study in unmitigated motion. Within minutes of returning from what I still refused to think of as a date, I was back on the phone, arranging to meet Todd again. I rationalized the secrecy, the closed door: I didn't want to confuse Tuck-well with transactions that weren't what they seemed. Not that I knew what they were, or could pick out from my old life the complicating new accompaniment.
I'm not built for change. I work at cultivating habit. Pull out tonight's meal to defrost before leaving; turn right at third stoplight; issue the collegial, automatic greeting. Habit is an index, a compromise with irreversibles, a hedge against auto wreck or disease. The arbitrary day requires a pretense of a priori. But defenses atrophy in quarantine. When I felt that first symptom, I slaughtered routine before it could dissolve on me. Crazy schemes — one day deciding to knock out the living-room wall. The instant the sledgehammer splattered plaster, I knew what I'd done. But a sickening sense of relief too: I'd never again have to worry about the wall caving in.
I was sick in my stomach pit, enough to extinguish a satisfactory existence. Tuckwell and I began to fall apart, wrecked in event. We'd committed no offense except the habit of living together. But all habit ends by presiding over its obsolescence. Even as I closed the door to the bedroom to arrange my next date, I felt I wouldn't be strong enough to end my old life cleanly. If I deliberately killed the old arrangement, everything would be killable. Escape rendered escapable whatever might follow.
Everything about Tuckwell — our apartment, shopping together, our trivial exchanges — grew horribly beautiful. I'd never treated him well. We'd failed to do the things we'd always talked about. I got nostalgic about the most bizarre items: shared wine bottles, accidental tears in the bed linen, utility bills. Even before I started seeing Todd in earnest, I sank into the death-denying compulsion of the collector. Countless times at the library, confronted by a perpetual crisis of shelf space, I've argued with Holdings that thirty-year-old sourcebooks ought not necessarily be pitched just because nobody had ruffled them since publication. Yet even as my heart clamped down to protect a life that had become as habitual as circulation, I knew that the place had already gone bloodless.
Deep in humid summer I felt the shameful excitement of spring cleaning, the sensory alertness brought on by an impending death. Explosion of taste, touch, sight: colors grew subtler, smells more variegated, more exciting because of their morbid source. I profited by another's agony. Three sick weeks, laced with the flavor of discovery, loss restoring the insight that recovery subsequently buries: however much I made love to it, I detested habit with everything in me.