1993-1994 Year Book - Carnegie Institution of Washington

ARNEGIE INSTITUTION

OF WASHINGTON

w

"** "■;-';,";!,:' ""'

Year £oo/c 93

1993-1994

astronomy • plant biology • developmental biology • earth and planetary sciences •

Office of Administration

1530 P Street, N.W.
Washington, DC 20005-1910
(202) 387-6400

Department of Embryology

115 West University Parkway
Baltimore, MD 21210-3301
(410) 554-1200

DEPARTMENT OF PLANT BIOLOGY

290 Panama Street
Stanford, CA 94305-4101
(415) 325-1521

Geophysical Laboratory

5251 Broad Branch Road, N.W.
Washington, DC 20015-1305
(202) 686-2410

Department of Terrestrial Magnetism

5241 Broad Branch Road, N.W.
Washington, DC 20015-1305
(202) 686-4370

The Observatories

813 Santa Barbara Street
Pasadena, CA 91101-1292
(818) 577-1122

Las Campanas Observatory

Casilla 601

La Serena, Chile

Cover: Scientists at the National Science Foundation
Center for High-Pressure Research at the Carnegie
Institution's Geophysical Laboratory employ the
diamond-anvil cell to study materials at the high pressures
of earth and planetary interiors. The sample is contained
between two facing diamonds, which are forced together
mechanically and which are transparent to x-ray, infrared,
and other radiation thus facilitating spectroscopic studies.
The instrument has been developed and improved during
the past two decades by Ho-kwang Mao, Peter Bell,
Russell Hemley, and colleagues at the Geophysical
Laboratory. See essays by Thomas Duffy and Yingwei Fei
in this year book, pp. 78-92. Photo: H.-k. Mao and J. Shu.

Carnegie
Institution

OF WASHINGTON

Year Book 93

The President's Report

July 1993-June 1994

Library of Congress Catalog Card Number 3-16716

International Standard Book Number 0-87279-672-8

Printing by Port City Press, Inc., Baltimore

Composition with Ventura /Postscript

December 1994

Contents

President's Commentary (Singer) 1

First Light and CASE (James) 15

Losses, Gains, Honors 20

Department of Embryology 25

The Director's Introduction (Brown) 27

News of the Department 28

Transposable Elements: Why They Move and Why

They Don't (Fedoroff) 29

Intracellular Movement and Metabolism of Lipids (Pagano) 36

Short Reports 42

Bibliography 45

Personnel 46

Department of Plant Biology 49

The Director's Introduction (C. Somerville) 51

Molecular Mechanisms of Plant Disease

Resistance (S. Somerville) 54

The Role of Membrane Lipid Composition (C. Somerville) 59

Short Reports 64

Bibliography 68

Personnel 71

Geophysical Laboratory 73

The Director's Introduction (Prewitt) 75

Properties of Hydrogen at High Pressure: Implications

for Jovian Seismology (Duffy) 78

Studying Core Materials at High Pressures and

Temperatures (Fei) 84

Short Reports 89

Bibliography 94

Personnel 101

in

Department of Terrestrial Magnetism 103

The Director's Introduction (Solomon) 105

The Mantle Beneath Continents (Carlson, Shirey,

Pearson, and Boyd) 109

The Tectonic Evolution of Venus (Solomon) 117

Bibliography 126

Personnel 131

The Observatories 133

The Director's Introduction (Searle) 135

Atoms and Stars (McWilliam) 136

Spectroscopy of Gas at High Redshift (Rauch) .... 142

Bibliography 148

Personnel 153

Extradepartmental and Administrative 155

Personnel 157

Publications 158

Special Events 159

Report of the Executive Committee 161

Abstract of Minutes of the 100th Meeting of the Board . 163

Financial Statements 165

Articles of Incorporation 179

By-Laws 183

Index 189

w

President and Trustees

PRESIDENT

Maxine F. Singer

BOARD OF TRUSTEES

Thomas N. Urban

Chairman
William I. M. Turner, Jr.

Vice-chairman
William T. Golden

Secretary

Philip H. Abelson
William T. Coleman, Jr.
John F. Crawford1
Edward E. David, Jr.
John Diebold
James D. Ebert
W. Gary Ernst
Sandra M. Faber
Bruce W. Ferguson
Robert G. Goelet
David Greenewalt
William R. Hearst III
Richard E. Heckert
Kazuo Inamori
Antonia Ax:son Johnson2
Kenneth G. Langone3
Gerald D. Laubach
John D. Macomber
Richard A. Meserve
Sally K. Ride2
Robert C. Seamans, Jr.4
David F. Swensen
Charles H. Townes
Sidney J. Weinberg, Jr.
Trustees

Caryl P. Ha skins
William R. Hewlett
William McChesney Martin, Jr.
Garrison Norton
Richard S. Perkins
Frank Stanton
Trustees Emeriti

1 From November 7, 1994

2 Resigned, May 6, 1994

3 From November 16, 1993

4 Trustee Emeritus from May 6, 1994

Former Presidents and Trustees

PRESIDENTS
Daniel Coit Gilman, 1902-1904
Robert S. Woodward, 1904-1920
John C. Merriam, 1921-1938
Vannevar Bush, 1939-1955
Caryl P. Haskins, 1956 -1971
Philip H. Abelson, 1971-1978
James D. Ebert, 1978-1987
Edward E. David, Jr. (Acting

President, 1987-1988)

TRUSTEES
Alexander Agassiz, 1904 -1905
Robert O. Anderson, 1976 -1983
Lord Ashby of Brandon, 1967-1974
J. Paul Austin, 1976 -1978
George G. Baldwin, 1925-1927
Thomas Barbour, 1934 -1946
James F. Bell, 1935-1961
John S. Billings, 1902-1913
Robert Woods Bliss, 1936 -1962
Amory H. Bradford, 1959-1972
Lindsay Bradford, 1940-1958
Omar N. Bradley, 1948-1969
Lewis M. Branscomb, 1973-1990
Robert S. Brookings, 1910 -1929
James E. Burke, 1989-1993
Vannevar Bush, 1958-1971
John L. Cadwalader, 1903-1914
William W. Campbell, 1929-1938
John J. Carty, 1916 -1932
Whitefoord R. Cole, 1925-1934
John T. Connor, 1975-1980
Frederic A. Delano, 1927-1949
Cleveland H. Dodge, 1903-1923
William E. Dodge, 1902-1903
Gerald M. Edelman, 1980-1987
Charles P. Fenner, 1914 -1924
Michael Ference, Jr., 1968-1980
Homer L. Ferguson, 1927-1952
Simon Flexner, 1910 -1914
W. Cameron Forbes, 1920 -1955
James Forrestal, 1948-1949
William N. Frew, 1902-1915
Lyman J. Gage, 1902-1912
Walter S. Gifford, 1931-1966

Carl J. Gilbert, 1962-1983
Cass Gilbert, 1924 -1934
Frederick H. Gillett, 1924 -1935
Daniel C. Gilman, 1902-1908
Hanna H. Gray, 1974 -1978
CrawfordH. Greenewalt, 1952-1984
William C. Greenough, 1975-1989
Patrick E. Haggerty, 1974-1975
John Hay, 1902-1905
Barklie McKee Henry, 1949-1966
Myron T Herrick, 1915-1929
Abram S. Hewitt, 1902-1903
Henry L. Higginson, 1902-1919
Ethan A. Hitchcock, 1902-1909
Henry Hitchcock, 1902
Herbert Hoover, 1920-1949
William Wirt Howe, 1903-1909
Charles L. Hutchinson, 1902-1904
Walter A. Jessup, 1938-1944
Frank B. Jewett, 1933-1949
George F. Jewett, Jr., 1983-1987
Antonia Ax:son Johnson, 1980-1994
William F. Kieschnick, 1985-1991
Samuel P. Langley, 1904 -1906
Ernest O. Lawrence, 1944 -1958
Charles A. Lindbergh, 1934 -1939
William Lindsay, 1902-1909
Henry Cabot Lodge, 1914 -1924
Alfred L. Loomis, 1934 -1973
Robert A. Lovett, 1948-1971
Seth Low, 1902-1916
Wayne MacVeagh, 1902-1907
Keith S. McHugh, 1950 -1974
Andrew W. Mellon, 1924 -1937
John C. Merriam, 1921-1938
J. Irwin Miller, 1988-1991
Margaret Carnegie Miller, 1955-1967
Roswell Miller, 1933-1955
Darius O. Mills, 1902-1909
S. Weir Mitchell, 1902-1914
Andrew J. Montague, 1907-1935
Henry S. Morgan, 1936 -1978
William W. Morrow, 1902-1929
Seeley G. Mudd, 1940 -1968
Franklin D. Murphy, 1978-1985
William I. Myers, 1948-1976

Paul F Oreffice, 1988-1993
William Church Osborn, 1927-1934
Walter H. Page, 1971-1979
James Parmelee, 1917-1931
William Barclay Parsons, 1907-1932
Stewart Paton, 1916 -1942
Robert N. Pennoyer, 1968 -1989
George W. Pepper, 1914 -1919
John J. Pershing, 1930 -1943
Henning W. Prentis, Jr., 1942-1959
Henry S. Pritchett, 1906 -1936
Gordon S. Rentschler, 1946 -1948
Sally K. Ride, 1989-1994
David Rockefeller, 1952-1956
Elihu Root, 1902-1937
Elihu Root, Jr., 1937-1967
Julius Rosenwald, 1929-1931
William M. Roth, 1968-1979
William W. Rubey, 1962-1974
Martin A. Ryerson, 1908-1928
Howard A. Schneiderman,

1988-1990
Henry R. Shepley, 1937-1962
Theobald Smith, 1914 -1934
John C. Spooner, 1902-1907
William Benson Storey, 1924 -1939
Richard P. Strong, 1934 -1948
Charles P. Taft, 1936 -1975
William H. Taft, 1906 -1915
William S. Thayer, 1929-1932
Juan T Trippe, 1944-1981
James W. Wadsworth, 1932-1952
Charles D. Walcott, 1902-1927
Frederic C. Walcott, 1931-1948
Henry P. Walcott, 1910 -1924
Lewis H. Weed, 1935-1952
William H. Welch, 1906 -1934
Gunnar Wessman, 1984 -1987
Andrew D. White, 1902-1916
Edward D. White, 1902-1903
Henry White, 1913-1927
James N. White, 1956 -1979
George W. Wickersham, 1909-1936
Robert E. Wilson, 1953-1964
Robert S. Woodward, 1905-1924
Carroll D. Wright, 1902-1908

Under the original charter, from the date of organization until April
28, 1904, the following were ex officio members of the Board of Trustees:
the President of the United States, the President of the Senate, the
Speaker of the House of Representatives, the Secretary of the Smithsonian
Institution, and the President of the National Academy of Sciences.

VI

Directors and Administration

PRESIDENT

1530 P Street, N.W., Washington, D.C. 20005

Maxine F. Singer President

DEPARTMENT OF EMBRYOLOGY

115 West University Parkway, Baltimore, Maryland 21210

Donald D. Brown Director
Allan C. Spradling Director-designate1

DEPARTMENT OF PLANT BIOLOGY

290 Panama Street, Stanford, California 94305

Christopher Somerville Director2

Joseph A. Berry Acting Director3

GEOPHYSICAL LABORATORY

5251 Broad Branch Road, N.W., Washington, D.C. 20015

Charles T. Prewitt Director

DEPARTMENT OF TERRESTRIAL MAGNETISM
5241 Broad Branch Road, N.W., Washington, D.C. 20015

Sean C. Solomon Director

THE OBSERVATORIES OF THE CARNEGIE INSTITUTION
813 Santa Barbara Street, Pasadena, California 91101

Leonard Searle Director

OFFICE OF ADMINISTRATION

1530 P Street, N.W., Washington, D.C. 20005

John J. Lively Director of Administration and Finance

Susanne Garvey Director of Institutional and External Affairs

Ray Bowers Editor; Publications Officer

Susan Y. Vasquez Assistant to the President

Marshall Hornblower Counsel

director, effective July 1, 1994
2From January 1, 1994
3To December 31, 1993

Vll

Carnegie Institution of Washington does not discriminate
against any person on the basis of race, color, religion, sex,
national or ethnic origin, age, disability, veteran status, or any
other basis prohibited by applicable law. This policy covers
all programs, activities, and operations of the Institution,
including administration of its educational programs,
admission of qualified students as fellows, and employment
practices and procedures.

Vlll

Presidents Commentary

^:#%

^P-~JS^;'v-- '- ^^

Administration building, Washington, D.C.

mmmsm

I

il:€ilf!

Magellan head Stephen Shectman inspects the Magellan mirror blank at the University of
Arizona s Steward Observatory Mirror Lab, April 28, 1994. The 6.5-meter-diameter mirror
had been gradually cooling inside its oven since its initial casting in early February 1994
The Magellan telescope is being built at Carnegie's Las Campanas Observatory Chile

President's Commentary

...fundamental science is in large part "strategic science" as well. The
difference is that the strategy is not directed toward finding practical
applications, but rather toward continually asking and seeking
answers to the most fundamental questions.... The measure of the
success of the strategy is the actual achievement of [this] fundamental
understanding.... It is success in this continuing endeavor that makes
it possible for infants whose brains differ very little from those of their
cave-dwelling ancestral counterparts, to become within two or three
decades, major contributors to this ongoing quest.

George W. Wetherill

letter to Thomas F. Malone

28 February 1994

Images of two magnificent events will dominate recollections
of the past year among scientists. Last winter, the Hubble
Telescope was repaired by a heroic team of astronauts, nearly
200 kilometers out in space. Later, in the summer, fragments of
the comet Shoemaker-Levy 9 bombarded Jupiter more than 600
million kilometers away. We watched both distant events as if we
were close observers, and in both we glimpsed the
interdependence of science and technology, albeit from different
perspectives.

The Hubble repair mission had a human purpose; indeed the
telescope itself exists to advance human knowledge of the distant
universe. The superb data that began flowing back to Earth soon
after the repair met with unrestrained enthusiasm among
Carnegie astronomers. Even as the astronauts were earning our
admiration aloft, improved technology was also advancing
science on Earth. The Geophysical Laboratory'sThomas Duffy
and Yingwei Fei, for example, using improved versions of the

CARNEGIE INSTITUTION

high-pressure diamond-anvil cell, were each acquiring
fundamental new data important for understanding the planet
(see essays by Duffy and by Fei, pp. 78-89). Like the astronauts,
Duffy and Fei were engaged in a venture having human purpose,
one requiring imagination, knowledge, and skill.

In contrast, the bombardment of Jupiter was beyond human
purpose or influence, almost beyond our imaginations, although
our ability to observe it depended on previous technological
accomplishments including the Hubble Telescope itself, the
Galileo spacecraft, and Earth-bound telescopes including the du
Pont Telescope at Carnegie's Las Campanas Observatory in Chile.

The Hubble repair and the Jupiter bombardment captured
widespread public attention. So too do new understandings
about fundamental biological processes relating to disease. Public
enthusiasm for science seems to be growing. Locally, we see that
interest in the large attendance at our monthly Capital Science
lectures. Meanwhile, however, a troubled discourse continues
bemoaning the effects of technology and modern science on
human life. This discourse is conducted largely by nonscientists.
It is marked by anxiety rather than the optimism typical of
scientists and apparent among many members of the general
public. For both good and unfortunate reasons, scientists rarely
speculate about the long-range implications of their work, many
of which are, in any case, not predictable. Deeming the public
discourse arid and beside the point, many scientists remain aloof.
Nevertheless, if science is to thrive, scientists and those who
support and depend on science need to think about the content of
the dialogue, recognize its significance, and make clear its
frequent folly.

The dialogue has two central themes. One is fear of the effects
of technological developments on human existence and on the
ecology of the Earth. The other perceives science itself as a
destructive challenge to humanity's faith in its own purpose.

The Fear of Technology

Technology is often the outcome of applying fundamental
scientific knowledge to human needs. Some see technology as
dangerous and dehumanizing. Sometimes it is. But, as the dean of
one of our nation's great medical schools once remarked to me, if
one is really sick, better to have as a doctor a businesslike,

Aerial view of Las Campanas Observatory, December 1993, shows preparation
for the Magellan telescope.

first-rate medical mind than a kind and sympathetic fool. Of
course, the ideal physician is a kind and sympathetic person with
a first-rate medical mind (like that dean himself), but such
perfection will rarely be on hand in emergencies.

In the course of history, we have become dependent on
technological innovation, on the skilled scientists and engineers
who produce the innovations and on entrepreneurial people who
see fortune in the innovations and are, accordingly, willing to take
considerable risks. Such commercial activities are undertaken
with attention to what people seem to need and want. They
require enormous investments in time, energy, and money,
requirements which restrain ventures that have no appeal in the
marketplace. Consumers have little trouble in making decisions
about the cost-effective utility of good and bad inventions, often
despite strenuous attempts through advertising to influence them
otherwise. Almost everyone would laugh at a suggestion that we
give up the use of fire because it's dangerous, or that we eschew
television because it has a bad influence on education and culture.

We have learned that there is no free lunch. Most technological
innovations bring new problems as well as new solutions.
Choices do need to be made, restrictions need to be considered
and, if necessary, imposed. Thus, technological innovations in
sanitation, medicine, and agriculture have led to unprecedented
increases in human population. If, as many believe, our species is
now using more than its sustainable share of Earth's space and
resources, the response must be conservation and limitation of
future population growth, not a return to open sewers, ineffective
medicine, and even more widespread starvation than now exists.

Yet, each technological innovation attracts worriers who

CARNEGIE INSTITUTION

would make us Luddite nay-sayers rather than responsible,
critical citizens. The worriers may not be in tune with most
people, but they gain credence through the cooperation of the
communications media. Technology itself has raised the media to
a dominant role in informing and shaping public opinion; but the
favor has not been returned. Reporting of scientific and
technological news is too often superficial, sensationalist, and
negative. Only rarely is the actual probability of undesirable
effects explained. Once the initial flurry of frightening front-page
reports has faded, ameliorating or even contradictory evidence
and interpretation is usually to be found in the back pages (or on
public broadcasting stations), if at all. All too frequently the
outcome is public hysteria followed by costly and inconclusive
new studies, needless antagonism toward industry, and
ill-conceived legislation. Recent objects of alarm include low-level
electromagnetic fields, the infamous "alar on apples," bovine
growth hormone, and a genetically engineered tomato, which has
been depicted as some sort of red menace.

A particularly egregious example was the media coverage, last
spring, of problems with long-term clinical studies to evaluate
alternative surgical treatments for early breast tumors. The initial
stories said little or nothing about the nature of the errors in the
studies, and left the impression that the medical conclusions were
wrong. Finally, the public learned that the problems were
managerial, and were neither venal nor scientifically
consequential. The validity of the studies' results was supported
by substantial independent data. Nevertheless, the media had
immediately implied the worst. It had drummed up terror within
the ranks of women who had chosen the treatment favored by the
studies — lumpectomy, rather than radical mastectomy. Then it
displayed that terror on front pages and prime-time television
through intimate and heart-wrenching interviews with women
led to believe they were the victims of dishonest, flawed science.

Alarmist media reporting and emotional dialogues confound
reliable assessment of real public opinion about technological
development. Of course, people want innovative technology to be
effective, safe, and relatively free from negative environmental
consequences — and they want honest information. But there is
also evidence that the public shares significantly in the optimism
of scientists. Opinion polls consistently report substantial support
for scientific research, particularly biomedical research, and

PRESIDENT'S ESSAY

relatively high esteem for scientists as professionals. People covet
innovative products based on science and technology, assuming
that the products perform as promised — everything from modern
transportation, fiber optics, computers, and instruments of
communication to foods and materials. Persons confronted with
serious or terminal illness seek out the newest medical technology.

Yet, the anxious dialogue continues, often in nostalgic tones
for what is romantically imagined to have been a safer, simpler
past. It would be more productive to recognize that the past is not
only forever gone, but that it wasn't always wonderful anyway. I
for one can't pass a swimming pool full of happy children
without remembering that pools were forbidden to me as a child
in the days before a polio vaccine was available.

Science as Scapegoat

Scientific understanding also troubles many people. It has
always been so. Perhaps the situation has improved since the
times of Galileo or Darwin, but the treatment accorded their ideas
still haunts us. Each time science reminds our species that we are
neither the center, the pinnacle, nor purpose of the history of the
universe, we can be certain that verbal hand-wringing or worse
will ensue from some quarter. Thus, we are being told, again, that
the current turmoil in human society, worldwide, has its roots in
the loss of historical, philosophical, and religious underpinnings,
and that science is to blame.

The labeling of science as scapegoat finds support among
many in positions of leadership. Such people may mouth
platitudes about science's importance to our national well-being
and, most recently, to our economic status, but they know little
about the content of scientific knowledge or how it is obtained. In
contemporary American society, significant intellectual
leadership is lacking, and it usually falls to scientists themselves
to counter the scientifically illiterate politicians and
commentators who dominate the media.

Statements of distress about the influence of science on the
human social order often begin with the issue of uncertainty and
finish with a yearning for the renewal of human purpose. In
between, it becomes clear that many individuals are deeply
troubled by the idea that random (or, more fashionably, chaotic)
events were instrumental in the history of the universe and of life.

CARNEGIE INSTITUTION
Fear of Uncertainty

Discussions of uncertainty by nonscientists usually start with
a weakly informed reference to Heisenberg's uncertainty
principle. It is said that this principle, which has to do with
intrinsic problems in determining the properties of atoms and
smaller particles, is responsible for widespread philosophical and
religious anxiety.

Can this really be a serious argument? It is unlikely that most
people even know about the uncertainty principle much less
understand it. After all, even Harvard graduates are revealed on
videotape record as ignorant of why summer and winter occur.
Moreover, anyone, educated or not, knows that certainty governs
much of our everyday lives: objects exist and usually remain in
the place we left them, night follows day, and living things
denied food and water will die. To paraphrase a remark in this
Year Book by Sean Solomon, the director of our Department of
Terrestrial Magnetism (DTM): Although the physical and
biological world is known to exhibit stochastic and chaotic
behavior, there is nonetheless an overarching optimism among
scientists that common physical and chemical laws (my italics)
underlie all phenomena.

Still, uncertainty exists, although it has little to do with
Heisenberg. Most people seem to accept it and, as the current
slang would say, "get on with their lives." Some uncertainties are
man-made, like the departure times of scheduled airplane trips.
More important are the uncertainties that come from our
ignorance about nature. We often don't understand well the
operation of those underlying common physical and chemical
laws Sean Solomon writes about. These uncertainties are what
motivate contemporary scientific research. For example, the
weather, earthquakes, and volcanic eruptions remain
unpredictable. Tumors arise when a series of mutations in certain
genes in a body cell release that cell from normal growth controls;
while some of those genes have recently been identified, most
tumors remain unpredictable and undetectable at very early
stages when nondisabling treatment would be effective. We
recognize that the growth in fossil fuel use, together with the
destruction of forests, is affecting the cycling of gases important
for sustaining life, but we are uncertain as to the outcome of those
changes.

PRESIDENT'S ESSAY

Other kinds of uncertainty are intrinsic to natural phenomena.
Thus, even if we learn to predict an oncoming volcanic eruption
or earthquake, the event itself remains the result of a set of chance
events. The collision of comet Shoemaker-Levy 9 with Jupiter was
accurately predicted more than a year ago, but the events that set
the comet's path are ancient and indeterminate. A baby will be
male or female depending on whether a sperm carrying an X or Y
chromosome happens to win the race up the Fallopian tubes to
the waiting egg. The series of mutations that lead to formation of
a tumor cell occur at random; although some mutagenic events
may be avoided by minimizing exposure to carcinogenic
chemicals or x-ray or ultraviolet light, many are intrinsic to the
normal function of cells. Thus, both biological systems and the
physical world must be recognized as imperfect as well as
uncertain. It is tempting to think otherwise. Multicellular,
multifunctional, and distinctive plants, worms, flies, amphibians,
and mammals develop, under genetic control, from single
fertilized egg cells, as described in the essays from the
Department of Embryology (pp. 25-45). However, errors caused
by genetic changes or environmental influences can occasionally
disrupt these complex and precise mechanisms, with disastrous
results. Still, the normal process of development is so amazingly

An open-top chamber used by
members of Carnegie's
Department of Plant Biology for
studying the effects of elevated
carbon dioxide on a grasslands
environment.

10 CARNEGIE INSTITUTION

reliable, successful, and even elegant, that we can understand
why it is often called a miracle.

But scientific understanding, by its very nature, cannot
incorporate the miraculous. Miraculous explanations end
questioning and stop scientific inquiry (Nor are scientific
discoveries themselves miraculous, as Charles James reminds us
in the following essay about First Light and the Carnegie
Academy for Science Education, but are the products of the hard
work of scientific inquiry) Orderly processes construct distinctive
living things and are the result of random trials, a great deal of
error, and a few successes over billions of years, not of miracles.
Biological evolution is the result of genetic tinkering. The
tinkering is not, however, undisciplined; it obeys the laws of
physics and chemistry And it produces viable, reproductively
competent organisms only if these organisms can interact
successfully with their immediate environments. This rather
messy process gave us the millions of living things with which
we now share the planet. Beautiful and amazing though they are,
none of Earth's living inhabitants is invincible. Error, disease,
even annihilation threaten them if they prove unable to cope with
predators or changing environments. Much the same can be said
of the nonliving objects in the universe.

In view of this, perhaps we could do away with the words
" truth" and "faith" in reference to science, as well as "miracle."
What science seeks is understanding — not truth, whatever that
may be. And, contrary to much anti-scientific writing, scientists
do not have "faith" in scientific understanding and facts. Quite
the contrary. They hold only tentative conclusions about any
particular scientific understanding — conclusions that become less
and less tentative as more and more phenomena are found to be
consistent with that understanding. In the 1950's, for example,
there was room for some skepticism as to the double-helical
structure proposed by Watson and Crick. Similarly, the
demonstration by Carnegie Institution scientist and future Nobel
Laureate Alfred Hershey that all the genetic information of a
bacterial virus is embodied in its DNA left open the possibility
that other molecules contributed to the transfer of genetic
information in other organisms. Now, just about all such doubts
are gone. The experimental results reported in this Year Book by
members of the Departments of Embryology and Plant Biology,
and similar results of experiments carried out hundreds of times

PRESIDENT'S ESSAY 11

each day in laboratories around the world, make sense only if the
properties of DNA are as they have been described. It is these
properties that permit successful laboratory manipulation of
DNA molecules and confirmable predictions of the consequences
of those manipulations when the altered DNA is introduced into
living organisms. Other good examples of how science
approaches increasingly more reliable descriptions of natural
phenomena are found elsewhere in this volume, for example in
essays by Thomas Duffy and by Sean Solomon on, respectively,
the evolution of models for the interior of Jupiter and the surface
of Venus.

The tentative, evolving quality of scientific understanding
unsettles many people. It appears to some to undermine a
common core essential for stability and reliability in human
society. It is often accused of implying moral and philosophic
relativism and a challenge to deeply held religious beliefs,
although science of course can say nothing about moral behavior
or religious beliefs.

Is a simultaneous commitment to scientific understanding and
religious faith incompatible? Individuals respond to this question
in several ways. Some turn away completely from traditional
religious faith. Others reject scientific explanations of natural
phenomena in favor of religious doctrine such as the biblical
explanation of creation. Many, including many scientists, accept
scientific explanations while remaining secure in their religious
faith. Still others struggle to reconcile these two views of the
universe and humanity. One element in that struggle, a
consideration that is often fed by the perplexing focus on the
uncertainty principle, is the question of human purpose. It is
argued that the loss of religious faith, together with the
displacement of our species from the pinnacle or center of the
universe, leaves us purposeless and without the foundation for
assuring social justice and human rights.

A Sense of Purpose

Scientific ideas and their technological offspring are the basis
of a worldwide commonality new in human history. This point
has been made by many, but perhaps most notably by Vaclav
Havel, one of the few bona fide visionary leaders to have
emerged in the late 20th century. Havel earned the right and

12 CARNEGIE INSTITUTION

respect to be heard by sustaining the vision of freedom for his
nation and making the vision a reality. Now he has turned his
thoughts to the global community. He recently described our
present approach to a new millennium as a "transitional period,"
a time when "all consistent value systems collapse," when
"everything is possible because our civilization does not have its
own spirit, its own esthetic."* Havel then went on to invoke the
global scientific and technological civilization as an instrumental
cause of the lost direction he perceives. Besides producing "a
state of schizophrenia" in which "man as an observer is becoming
completely alienated from himself," Havel held science
responsible for the disappearance of God from the world — and
with Him the source of "the traditional foundation of modern
justice," the set of values embodied in the American Constitution
and Bill of Rights.

There is substantial evidence opposite to Havel's perceptions.
Although the American founding fathers stated the grounds for
human rights in religious terms tempered by the concepts of the
Enlightenment, some present-day religious movements
themselves present dangerous challenges to human rights, both
in the United States and elsewhere in the world. If anything,
science runs counter to such influences. Whether they are people
of faith or not, scientists know that the scientific enterprise
depends on freedom and human rights: the individual's freedom
to think and question and the right to participate.

In joining his concerns about contemporary society to the
forthcoming end of the millennium, Havel attaches a mythical
significance to this junction. We should be wary of such thoughts.
More than a decade ago, A. Bartlett Giamatti warned that
millennial passages invite false philosophy.

All this is preamble to where we think we are, beginning a
new decade, beginning the end of a century, ending the second
millennium. Humankind becomes more consciously
retrospective the more it fears the seemingly uncontrollable
accumulation of the past, and so it is with us.... We hear on all
sides that we are weak; that knowledge is exploding
unmanageably; that the pace of uncontrollable events is
exacerbated by instantaneous communication; that technology
is a beast biting its own tail; that ideology is insufficient to an

*V. Havel, "The Measure of Man," Speech at Independence Hall, Philadelphia,
luly 4, 1994, upon receiving the Philadelphia Liberty Medal; as published, The New
York Times, July 8, 1994, p. 27.

PRESIDENT'S ESSAY 13

exploding reality; that the family is in decline; that traditional
values are devalued; that standards, for work and play and
quality of life, are gone.

I believe that the new wisdom of a century's end is really
only fatigue masquerading as philosophy. I urge you to
beware the captivation of these easy, thoughtless profundities.
These banalities have only in common the belief that we are
not able to give definition — shape and contour — to what is
around us. These shibboleths finally tell more about those who
utter them than about reality. They are expressions of
exhaustion more often than they are forms of explanation.*

Havel does not stop with his diagnosis of the world's troubles.
He follows it with a surprising and disturbing prescription for a
new, unifying human perspective. He properly notes that
scientific concepts interconnect human life, the ecosystem of our
planet, the cosmic events that formed the solar system, and the
universe itself. But unlike the reports in this Year Book, he seeks
these interconnections not in hard-won, demonstrable realities,
but in the vague, romantic ideas embodied in the "anthropic
cosmological principle" and the "Gaia hypothesis." The former
sees the universe as in the service of humankind and our
demonstrable connection to the universe as some sort of a
mysterious anchor. The latter cloaks in mythology the
scientifically evident interdependence of Earth's physical
attributes and the properties of life. In Havel's view, these
concepts can redeem science and humanity as well.

Crises do exist all over our planet. The passing of a
millennium will make them neither better nor worse. And science
cannot be blamed for them. Rather, the timeless human
proclivities are at work: greed, xenophobia, nationalism,
intolerance. Neither can science rescue us from the crises. Havel
cannot foist on science a transcendent purpose that will banish
evil and substitute for earlier mysticisms and mythologies.

But science need not be antithetical toward human concerns.
Without romantic decorations and independent of questions of
faith, science can help resolve some predicaments. Six years ago
in these pages I wrote that we scientists believe that the quest for
better understanding is a fundamental human trait, one that sets
Homo sapiens apart from other living species. Scientific inquiry
thus confirms a unique identity and a special purpose for humans

*A. Bartlett Giamatti, A Free and Ordered Space: The Real World of the University, W.
W. Norton, New York, 1981, 1988, pp. 295-296. © W. W. Norton.

Charles James (standing) talks to elementary-school teachers at a session ot
the Carnegie Academy for Science Education (CASE) in the First Light lab.

compared to other organisms.

Can scientists, by sharing more effectively their knowledge,
their ignorance, and the nature of their endeavor, convince
nonscientists of the worthiness and significance of their venture?
George Wetherill's words, quoted at the start of this essay, convey
science's timeless goal, to accumulate fundamental
understanding, and also suggest the necessity of enlisting
succeeding generations in the quest, without which the quest
must fail.

Sharing Science

All of which is easier said than done. We don't know well how
to share scientific concepts with nonscientists, although we are
constantly trying to improve communications. The vocabulary
and concepts needed for this exchange are not, however,
embedded in many of the brains we are trying to reach; the
software has not been loaded. In this Year Book, for example, we
strive to write plainly about complicated ideas. If I compare this
volume, or the talks on front-line science delivered at the monthly
Capital Science lecture series at P Street, with much current
writing in the humanities, it seems that science is not doing so
badly. The language of literary scholarship has become
increasingly dense, infested by incomprehensible jargon of
vocabulary and construction; it is difficult to know whether the
ideas are more profound or sophisticated than those of earlier
literary scholars. Science, however, grows unquestionably more

PRESIDENT'S ESSAY 15

sophisticated, and sharing it has become more and more difficult
even as it becomes more and more important.

The Carnegie Institution is continuing its efforts to share
science effectively. Our Capital Science lectures are popular,
attracting a surprisingly large and diverse audience of
Washingtonians thanks to the hard work of Susanne Garvey and
her staff. Our scientists often work with science journalists,
helping them explain our work to their readers, and have
themselves written books for nonspecialist readers and articles in
magazines like Scientific American. First Light, entering its sixth
year, is renewed each year by eager children and its tireless,
imaginative director, Charles James. This past year, the Carnegie
Academy for Science Education (CASE) began its five-year
program to retrain 450 D.C. elementary-school teachers for
teaching modern science in an experiential mode; Mr. James and
Dr. Ines Cifuentes, the leaders of CASE, are already well-known
and admired around the city. The Department of Embryology
continues with various efforts directed at high school teachers
and students in Baltimore. New ideas for ways to share are being
developed at DTM, and summer research experience for high
school students and undergraduates is provided at several
departments. We prepare booklets about Carnegie science for top
high school students and their teachers. Vigor and discipline, not
hand-wringing, are the Carnegie style.

— Maxine Singer
November 1994

First Light and CASE

by Charles James*

Our First Light Saturday science program for neighborhood
elementary-school children is now in its sixth year. Meanwhile
the Carnegie Academy for Science Education, or CASE, where we work
with the city's elementary-school teachers, is in its first. A common set of
ideas link the two ventures; indeed, CASE might be appropriately named
Second Light, after the lessons and experiences of its model. Some, indeed

*Director, First Light; Director of Curriculum, Carnegie Academy for Science
Education (CASE)

16 CARNEGIE INSTITUTION

many, of the details in both programs have been adapted from innovative
ventures elsewhere. But neither the details nor the general approach of
First Light and CASE are yet widely seen in educational systems. Perhaps
part of the reason lies in public misperceptions as to the nature of science
and discovery.

In Thomas Edison's 1923 advertisement for his new invention, the
dictaphone, he proudly wrote: "It worked the first time." Given
Edison's genius perhaps the statement is true, but it is assuredly not the
common occurrence among inventors and scientists. Even Edison
experienced frustrations, as his work on the electric lightbulb was both
long and full of failures. Indeed, by 1879 Edison and no fewer than 25
other scientists had produced working but dead-end prototypes.
Edison's final patented "perfected model" rested upon the
extraordinary insights of many who had gone before, along with the
able help of his assistant Lewis Latimer, and hours of insightful errors.

How the conventional story of Edison's lone "miraculous"
discovery began is understandable. Behind such romanticized notions
of science is a yen to find miraculous revelation in what is often a
frustrating and tedious search, perhaps also a wish to celebrate the
achievements of the present rather than share credit with prior
generations. But perhaps, too, the case is indicative of a general
misperception of science itself.

Both science and science education have been troubled by the
perception of "instant science," where discovery belongs to a moment
in time and a few chosen individuals. For science educators, this
misperception seems to remove individuals from personal involvement
in scientific reflection and discovery. Our children read about
somebody else's discovery of new knowledge, but they are not led to
widen their own experience as a means to personal discovery. Edison's
career shows that there is no special way, no special place of instruction
required to learn science, only special places of reflection to prepare
and reveal the meaning.

CASE: The First Summer

In summer 1994 Carnegie Institution offered such a place of
reflection for some fifty Washington, D.C. public-school teachers.
During their participation in the CASE program at the Carnegie main
building on P Street, teachers from prekindergarten through grade six
began to reflect in new ways on their role in science education. For
most, it was by admission the first time in many years that they had
focused on science. For six weeks, the CASE fellows were exposed to
speakers, resources, software, and various interactive activities, each
highlighting different aspects. Math, technology, pedagogy, instruction,
and assessment were explored in many dimensions. CASE

Maxine Singer gives a lesson in genetics at a session of CASE, July 1994.

developmental activities ranged over many topics, from electricity and
energy to properties of water. Each fellow approached each activity as a
student would, thereby acquiring the student's outlook even while
gaining a protocol for the teacher's own use. For most of the
participants, it was a new experience; such topics and approaches had
been largely absent in their classrooms.

The activities required full participation. On Toy Day, participants
raced about chasing propellers and spinning wings. They felt the sting
of their muscles while powering a simple twirling of a toy. Each toy
had a lesson about movement and energy. In other activities, some
participants for the first time realized that the gardener and cook are
science literate. In short, CASE fellows came to realize that there is no
aspect of our world that is not science.

The participants were encouraged to make models — plastic models
of islands, for example, where the various formations sculpted by their
hands could be identified and described. They made topographic and
physical maps of their models and added sustaining industries. When a
new CASE topic was introduced, it was often with a strong element of
student interaction. Fellows were handed a brown-paper bag
containing a mineral specimen and were asked to describe the sample
in at least a dozen different ways. The specimens were later revealed to
all and the descriptions were read. Individuals were asked if they could
identify the mineral being described. Thus, the participants learned that
students may forget the names of minerals but can benefit from the
skillful description of an observation.

The CASE program is being supported by generous five-year
grants from the National Science Foundation and the Howard Hughes
Medical Institute. The day-to-day administrator is the director, Ines
Cifuentes, previously a Carnegie postdoc in seismology. Help from the
scientists of Carnegie Institution has been gratifying: Maxine Singer,
Vera Rubin, Bob Hazen, and Chris Field offered instructional dialogues
with the participants, and the Department of Embryology hosted the
entire CASE group for a morning of lab activities in the areas of

18 CARNEGIE INSTITUTION

classification, genetics, and the development of life. Other field
experiences included a comprehensive look at the geology of
Washington, a visit to the new Challenger Center, and a day-long visit
to the Chesapeake Bay and du Pont Research Farm in Chesterton,
Maryland. Meanwhile, the curriculum included a strong effort to
reinforce and expand knowledge and understanding of today's science
among the participants.

CASE participants earned credits at Trinity College and a weekly
stipend. Fifty enrollees completed the summer's program, including
nearly all science coordinators of the District's schools. A strong
cameraderie became unmistakable among the fellows, who came
quickly to understand and share the CASE philosophy. Meanwhile,
those of us who planned and led the program came to know the
extraordinary strengths of these individuals, who quickly became our
colleagues for action. They have now returned to their own schools
filled with these ideas, along with notebooks full of science curricula
and the materials needed to perform the interactive activities in their
own classrooms, and — perhaps most important — heightened
motivation and confidence for bringing science to children.

Unlike Thomas Edison, we will not boast that CASE "worked the
first time." CASE is a start toward reform in the District's elementary-
school curriculum. Our goals will not be achieved in a single summer
or year. We will be working with the 1994 participants in visits and
meetings throughout their school year, and next summer — aided by a
number of mentor teachers from the first group — we will enroll a
hundred new participants. The lessons we learned and are learning will
feed back into our future efforts.

First Light Continues

In spring 1994, First Light became involved in a project with the
University of Delaware at Luce. On April 12, 1994, thirty floating
devices were placed in the Delaware Bay. Each device was fitted with a
radio signal that was monitored by satellite. Each day the positions of
the floats were recorded, and the information sent to the youngsters.
Pretty exciting stuff, made even more so by an accompanying
challenge. The children were asked to learn as much as they could
about offshore currents and predict where the floats would be on the
seventh day. The closest guess would win a book and small cash prize
from the University of Delaware. Within several sessions, the children
learned how to read latitude and longitude in degrees and minutes. (I
have seen geography classes take weeks to do the same.) Once they
became proficient at reading the map, the sometimes frustrating
challenge of science arose in the form of questions significant to all
scientists: What if...? What are the chances of...?

FIRST LIGHT AND CASE 19

We all learned a great deal about offshore curents, wind, and water
density. We learned that a float can be carried three days off course by
wind and then recover the same distance in one day because of
currents. We learned that there are more chances of being wrong than
right. We learned that science is a process of closing gaps with each
disappointment, that success comes from a diversity of approaches
applied to a problem. The final insight is rarely a direct shot.

Welcome to Fruitvale. Fruitvale is a tiny town in need of expert
advice. Water contamination has been a problem, and the town needs
to know the source of the contamination. The First Light children were
organized into several groups; each was given a budget, a town map,
and instructions to design a plan for solving Fruitvale's problems. Our
students at once realized that there is underground water, and began
asking about aquifers. We made an aquifer. They asked about the
effects of pesticides on ground water. We explored relevant
information. Groups devised ground-testing strategies. Were they
useful? We looked to examples in archaeology. Is a scatter pattern or
cross-sectional pattern of testing better? Finally, the testing began.
When groups ran out of money they were forced to sell some of the
information they had gathered in order to cooperatively find the source
of contamination. It ended up that the culprit was a dump site. Not the
chemical factory, not the farm, as some groups initially guessed. Each
time our students came upon a wrong answer they were closer to
discovering the source. Eventually they succeeded. So did First Light.

Why does First Light advocate this kind of approach? Abandoning
notions, trials, and retrials take time. Couldn't just delineating the facts
without equivocation work, just as it does with spelling?

But there's a difference. Science is continuous motion of thought
brought to bear on a particular set of problems. However profound
science concepts are when standing alone, they are not embedded in
the mind until applied. The application must be real and not placed
under the guise of some poorly constructed pseudo-investigation
where every observation has a predetermined answer — one that the
student writes in the appropriate place, properly titled and without
mistake. Successful science for the elementary grades challenges the
student to use the freedom offered to decide the information needed,
determine it, and apply it. Being wrong is decidedly not a failure.

It is our hope that the children will become life-long learners who
tackle science because they have found that active and thoughtful
reflection is both satisfying and enjoyable. Science is a basic
impulse — an asking of questions, not a compendium of knowledge.
Our work with the principals, teachers, and children in First Light will
remain central in our efforts. The newly installed computers used for
CASE will open new levels of experience for the First Light children.

First Light and CASE will continue to prepare and guide children's

20

CARNEGIE INSTITUTION

reflections about the world through experiencing science. We as guides
are committed to help bring this scientific way of thought to them, both
directly and, with CASE, through their teachers. Our goal is to return
the children to the inquiring nature of science that is innate to all
youngsters. The door we wish to open for them is at once at the root of
intellect, wonder, and the many good myths we all embrace.

Losses, Gains, Honors

Former Carnegie trustee Franklin Murphy, chairman emeritus of
the Times Mirror Company, died June 16, 1994, at the age of 78.
Murphy served on the Carnegie board from 1978 until 1985. He
was a member of the Nominating Committee for three m

years (1979-1981) and was chairman of the committee
for one (1981).

Lawrence Hafstad, a staff member at the Department of
Terrestrial Magnetism from 1928 until 1946, died October
12, 1993. He came to DTM from the University of Minnesota
and later, while serving at the Department, earned his Ph.D.
from Johns Hopkins University. At DTM, he joined Merle
Tuve and Norman Heydenburg in performing what has
been called one of the most beautiful experiments in nuclear
physics, showing that the nuclear component of the force
between two protons was attractive and equal to the force
between a neutron and a proton. Hafstad was an early leader
in the development of the proximity fuze, and served in the Applied
Physics Laboratory throughout World War II, succeeding Tuve as its
director in 1946. In 1948, he returned to nuclear physics, becoming
the first director for reactor development with the Atomic Energy
Commission. Then, in 1955, he became vice president and executive
in charge of research at General Motors Corporation, and he served
in that role until his retirement in 1969.

Clinton B. Petry, an accountant at the Geophysical Laboratory
from 1966 until his retirement in 1976, died January 30, 1994.

Retired custodian Thomas Miller, who worked at the Department
of Embryology from 1973 until 1985, died on April 24, 1994.

Lawrence Hafstad

Louis Brown, staff member at DTM since 1964 and a Carnegie
fellow from 1961 until 1964, became a staff member emeritus in
February 1994. Early in his tenure at DTM, Brown conducted research
on the interaction of polarized protons with atomic nuclei, in
collaboration with scientists at the University of Basel, Switzerland. He

LOSSES, GAINS, HONORS 21

was a leader in developing techniques of accelerator mass spectroscopy
for using isotopes of beryllium to study island-arc volcanism. Brown
served as acting director of DTM from July 1991 to August 1992.

Richard Pagano, a staff member at the Department of Embryology
since 1972 and a pioneer in lipid biology, resigned in November 1994 to
assume a position at the Mayo Clinic Foundation, Rochester, Minnesota.

Geochemist Julie Morris, a staff member at DTM since 1987 and a
postdoctoral fellow there for the previous three years, resigned in
December 1993. She is currently at Washington University, St. Louis.

Gains

Ian Thompson was appointed a staff member at the Observatories
on January 1, 1994. He has served at the Observatories since 1981,
first as a Carnegie fellow, then as research associate and staff associate.
Thompson holds the Ph.D. in astronomy from the University of
Western Ontario (1981). Much of his recent research has been in
studying the stellar populations of globular and open star clusters. He
is especially interested in low-mass stars, which emit only feeble light
and thus may contribute significantly to the universe's missing dark
matter. He has also designed and supervised the building of
CCD-based systems in use at the du Pont and Swope Telescopes at Las
Campanas.

Erik Hauri joined DTM in February 1994 as staff member in
geochemistry. Hauri completed his Ph.D. in 1992 in the M.I.T. -Woods
Hole Oceanographic Institution Joint Program in Oceanography and
remained at Woods Hole as a postdoctoral investigator for another
year. His research involves trace element and isotopic studies of
mantle-derived lavas and ultramafic rocks, and high-pressure
petrologic experiments, applied to the study of problems in
geodynamics. A particular focus of his work has been on mantle
plumes in oceanic intraplate settings.

Conel Alexander became a DTM staff member in cosmochemistry
in August 1994. Alexander received his Ph.D. in experimental physics
from the University of Essex in 1987, and continued his research as a
fellow in the earth sciences department of the Open University, Milton
Keynes, England. From 1989 until August 1994, he was a senior
research associate in the Department of Physics at Washington
University, St. Louis. Alexander studies pre-solar grains in meteorites.
He also works to interpret the classes and populations of stars which
may have been the source of such grains.

Marnie Halpern arrived at the Department of Embryology as staff
member in August 1994. Halpern received her Ph.D. from Yale
University in 1990 and was a postdoctoral fellow at the University of
Oregon, Eugene, from 1990 until 1994. Her research focuses on

22

CARNEGIE INSTITUTION

vertebrate development, particularly on the development and
patterning of the central nervous system. She uses as her model system
the zebrafish.

Christopher Somerville and Shauna Somerville, whose
appointments were described in Year Book 92, arrived at the Department
of Plant Biology in January 1994 as director and staff member,
respectively

Peter de Jonge was appointed Magellan project manager at the
Observatories in August 1993. As such, he oversees the engineering and
design specifications of the Magellan telescope, now being built at Las
Campanas. He holds a degree in applied physics from the University of
Delft, the Netherlands, and has had many years of experience
overseeing telescope construction and operation, both in Europe and
Chile. He received the prestigious Legion d'Honneur medal in 1988.

Honors

Frank Press, the Cecil and Ida Green Senior Fellow at DTM and
the Geophysical Laboratory, received a National Medal of
Science at an awards ceremony at the White House in December 1994.
He was cited for "his contributions to the understanding of the nature
of the deepest interior of the earth and for his contributions to the
nation, the National Academy of Sciences, and the academic world."
Press also received the 1993 Pupin Medal, presented in November 1993
by the Engineering School Alumni Association and the School of
Engineering and Applied Science, Columbia University. In April 1994,
Press delivered the 1994 William D. Carey Lecture at the 19th Annual
American Association for the Advancement of Science Colloquium on

Frank Press (left) holds the Vannevar Bush Award, presented to him on May 4,
1994, at the Department of State. With him are his wife, Billie, and James J.
Duderstadt, National Science Board Chair and president of the University of Michigan.

LOSSES, GAINS, HONORS 23

Science and Technology Policy in Washington, D.C. He received the
Vannevar Bush award at the National Science Board's annual dinner at
the Department of State in May 1994. The award acknowledged his
outstanding contributions in science and technology significant to the
nation's welfare. In June 1994, he received an honorary Doctor of
Science degree from the University of Western Ontario.

Winslow Briggs, director emeritus of the Department of Plant
Biology, received the Stephen Hales Prize in July 1994 from the
American Society of Plant Physiologists "for serving the science of
plant physiology in three major ways: as a teacher and mentor of plant
scientists at different levels of their careers (undergraduate, graduate,
and postdoctoral scholars); as an investigator who has enlarged our
understanding of how light interacts with internal metabolic and
hormonal control of plants to affect their growth and development; as a
senior spokesperson for plant physiology and plant biology in general."

DTM staff member Vera Rubin received the Carnegie Mellon's
Dickson Prize in Science on November 9, 1994. She received an
honorary Doctor of Sciences degree from Williams College at the
October 1993 celebration of the 200th anniversary of the college's
founding. She presented the Jeffrey Bishop Lecture at Columbia
University in October 1993, the Antoinette de Vaucouleurs Lecture at
the University of Texas in November 1993, and the 1993-1994 Russell
Marker Lecture in Astronomy and Astrophysics at Pennsylvania State
University in September 1994. She was also the keynote speaker at the
first annual program to honor women in science and engineering
(WISE) held in April 1994 at the National Academy of Sciences. Her
late-1993 National Medal of Science was described in Year Book 92.

The Observatories' Wendy Freedman was selected to receive the
1994 Aaronson Prize for her work on stellar populations and the
extragalactic distance scale.

DTM director Sean Solomon was elected president of the American
Geophysical Union in February 1994 for the biennium 1996-1998; he
serves as president-elect for 1994-1996.

DTM staff member Alan Linde received the Geological Society of
Washington award in December 1993 for the best technical paper read
before the society during 1993. His paper was about the 1991 eruption
of Hekla.

Embryology staff member Richard Pagano (who resigned in
November 1994) was the Merck-Frosst Canada Distinguished Lecturer
at the University of Alberta in December 1993.

The Geophysical Laboratory's Hatten S. Yoder, Jr., was elected
president-elect of the International History of Earth Sciences Society. He
is also the vice president of the Public Numbers Association of the
Foreign Service, which is an advisory group to the Department of State.

Andrew McWilliam, McClintock Fellow at the Observatories,

Edna and Caryl Haskins examine a copy of This Our Golden Age, a new book,
edited by James Ebert, reprinting several annual essays that Haskins wrote for the
Year Books during his tenure as Carnegie president (1956-1971). The Haskinses were
honored at the Friday luncheon following the May meeting of the Board of Trustees.

received the 1995 A AS Newton Lacy Pierce Prize in Astronomy.

Geophysical Laboratory postdoctoral fellow Kathleen Kingma
received the Jamieson Award at the 1994 Gordon Conference on High
Pressure. She was honored for excellence in research as a graduate
student.

Horatio Frydman and Denise Golgher, predoctoral fellows at the
Department of Embryology and graduate students at Johns Hopkins,
received Du Pont Teaching Awards from E. I. du Pont de Nemours and
Co. for being the "best graduate student teaching assistants" in the
Hopkins Biology Department. The two are husband-and-wife.

Heather Weir, DTM research intern during 1993-1994, was one of
five 1994 student honorees at the first annual program to honor women
in science and engineering (WISE) held in April 1994 at the National
Academy of Sciences.

Former Geophysical Laboratory fellow Ross Angel, now at the
Bayerisches Geoinstitut, received the Max Hey Award from the
Mineralogical Society of Great Britain and Ireland.

Carnegie Trustee Edward E. David was inducted into the Georgia
Institute of Technology Hall of Fame this year.

W. Gary Ernst was elected to membership in the American
Philosophical Society.

Richard Meserve was elected a Fellow of the American Academy of
Arts and Sciences.

Robert Seamans, Jr. received the 1994 Arthur M. Bueche Award on
October 5, 1994, from the National Academy of Engineering.

Emeritus trustee Frank Stanton received a Lifetime Achievement
Award from the Business Enterprise Trust on November 9, 1993.

Charles Townes was selected to receive a Doctor Honoris Causa
degree from the Ecole Normal Superieure.

Carnegie president Maxine Singer received honorary degrees from
Yale University and Harvard University.

Department of Embryology

Caenorhabditis elegans

Members of the Department of Embryology, summer 1994. Bottom row sitting (left to
right): Earl Potts, Ron Millar, Glenese Johnson, Wanda Brown, John Margolis, Ping
Zhang, Chris Norman. Second row sitting: Helen Georgieva, Nipam Patel, Bill Kelly,
Allison Better, Kentaro Hanada, Amy Atzel, Una Savage, Mary Montgomery, Brian Calvi,
Jessica Blumstein, Hai-fan Lin, Donald Brown. Third row sitting: Allison Pinder, Eileen
Hogan, Dianne Stern, Michael Schlappi, Elizabeth Helmer, Susan Dymecki, Stacey
Hachenberg, Linda Keys, Maggie de Cuevas. Fourth row sitting: Mary Strem, Irene Orlov,
Tom Haas, Pam Meluh, Rebekah Pagano, Rob Schwartzman, Alejandro Sanchez, Dave
Furlow. Fifth row: Liz Mendez, Chris Murphy, Alexander Strunnikov, Vinni Guacci, Brian
Eliceiri, Pete Okkema, Michele Bellini, Zheng-an Wu, Joe Gall, Pascal Paul, Herbert Wu,
Ona Martin, Mary Lilly, Dianne Stewart, Ellen Cammon. Sixth row: Joe Vokroy, Kris
Belschner, Joohong Ahnn, Pat Englar, Chelsea Davis, Jennifer Abbott, Donna Bauer, Mike
Sepanski, Alexander Tsvetkov, Jeff Kingsbury, Luca Pellegrini, Bill Kupiec, Chii-shiarng
Chen, Andy Fire, Doug Koshland, Allan Spradling, Horacio Frydman, Ben Remo.

The Director's Introduction

When I became director of this department in 1976, the field
of embryology, or developmental biology as we had begun
to call it, was still in its "biochemical era." The methods of
biochemistry, as instructive as they were for many questions in biology,
permitted only the crudest experiments for studying how genes
participate in development.

We did not imagine that there were techniques soon to be
discovered that would revolutionize developmental biology. These
advances combined genetics and molecular biology in a way that has
made possible the clarification of some of the most venerable problems
in the field. One of the pioneers who recognized the importance of this
merger of methods and disciplines was Allan Spradling. In 1982
Spradling and Gerald Rubin discovered how to introduce genes into
the fruit fly, Drosophila. This advance revolutionized the discipline of
genetics, which had relied for a century on the identification of
mutations by tedious screening of the progeny of many matings.
Spradling and Rubin showed that any gene of interest could be cloned,
altered in the test tube, and then reintroduced into the living organism
to become an integral part of the animal's own genetic material. Since
then, this strategy has been applied to other organisms, and it now
represents the most powerful approach that exists in modern biology to
enhance our understanding of gene function. In addition, it forms the
technical and intellectual basis for gene therapy.

Not only has Allan Spradling changed how genes are studied, but
his research on tissue-specific gene expression has made his laboratory
one of the preeminent ones in the world. It is fitting, therefore, that he
assume the directorship of this department in an era when
developmental biology has become the most exciting and rapidly
moving field in modern biology.

My plan for the immediate future is to return to my laboratory and

27

Donald Brown (center) with Allan Spradling (left) and Joseph Gall, at a party held
at the Department to welcome Spradling as director, effective 1 July, 1994, and to
honor Brown.

resume my original position as a staff member and bench scientist. If
my 18-year term as director has proceeded smoothly, it is because of the
superb assistance of our supporting staff. I am grateful to Sue Satchell
who explained our finances to me each year. Pat Englar has always
maneuvered through the most complicated procedures and forms
without a complaint or even a frown. Sheri Rakvin, Christine Norman,
and Lori Steffy are quietly efficient, and all of them together have made
it a pleasure to come to work every day.

A visiting committee report once said that our department
functions with no trace of administration. I think that was a
compliment.

Nezvs of the Department

Our seminar program was highlighted by the Seventeenth Annual
Carnegie Minisymposium, entitled "The Architecture of the Nucleus."
Laura Davis, John Sedat, Kenneth Carter, Gideon Dreyfuss, David
Spector, and John Newport presented one-hour talks.

Support of research in the Department comes from a variety of
sources besides the Institution. Allan Spradling and various members
of his lab are employees of the Howard Hughes Medical Institute. We
are grateful recipients of individual grants from the National Institutes
of Health, the John Merck Fund, the Arnold and Mabel Beckman
Foundation, the McKnight Endowment Fund for Neuroscience, the G.
Harold & Leila Y. Mathers Charitable Foundation, the American Cancer
Society, the Jane Coffin Childs Memorial Fund, the Helen Hay Whitney
Foundation, the Damon Runyon-Walter Winchell Cancer Fund, the
Rita Allen Foundation, and the Human Frontier Science Program. A
grant to purchase small instruments and a Biomedical Research
Support Grant to the Department from the National Institutes of Health
are gratefully acknowledged. We remain indebted to the Lucille P.
Markey Charitable Trust for its support.

— Donald D. Brown

EMBRYOLOGY 29

Transposable Elements: Why They Move
and Why They Don't

by Nina Fedorojf

Half a century ago Barbara McClintock discovered that certain
bits of DNA are able to move from one chromosomal position to
another. She identified these mobile DNA segments, which she called
transposable elements, in maize plants. Several decades then elapsed
before transposable elements were discovered in enough other
organisms, ranging from bacteria to humans, for wide acceptance of the
concept that mobile genetic elements are a regular feature of genome
structure. Today, transposable elements and DNA segments having the
structural features of mobile elements have been identified in virtually
every organism in which they have been sought. And some
transposable elements have been studied in sufficient detail to reveal
the existence of sophisticated mechanisms responsible for their
movement.

Yet almost fifty years after their discovery, the role that
transposable elements play in the development and evolution of
organisms remains an enigma. With time it has become increasingly
evident that excessive movement of even a single one of the many
transposable elements in an organism can be extremely harmful. When
a transposable element inserts into a gene, the gene's sequence is
interrupted and the gene's ability to function may be disrupted. If an
element inserts into a gene's regulatory sequence, while it may not
harm the gene, it may instead change the gene's pattern of expression
in the organism, causing it to be silent when it should be active and
active when it should be silent. In addition to such genetic changes
from insertion in or near a gene, the very movement of transposable
elements often causes breaks and rearrangements of chromosomes.
Thus genetic damage of one type or another is the primary
consequence of transposition.

An organism's chromosomes are often laden with dozens or
hundreds of copies of any one transposable element, of which there are,
in turn, many groups, or families. The mobilization of just one family
can result in damage at many chromosomal sites simultaneously. The
puzzle, then, is why transposable element damage is relatively rare.

The emerging answer is that molecular mechanisms exist whose
purpose is to keep transposition at a minimum and under strict control.
Research in our lab on the transposable elements of maize has
uncovered an altogether unique mechanism that can maintain the

The Spm element

transcription start site

_i

1 kb

CACTACAAGAAAA

[~ J Subterminal repetitive (TnpA-binding) regions

(the region adjacent to start site contains the promoter)

TTTTCTTGTAGTG

Spm protein-coding sequences (ORFs)

•TnpB-

^H

>l

-TnpC

>h

-TnpD-

>h

-TnpA-

Fig. 1 . A diagrammatic representation of the Spm element, its transcripts, and its
protein-coding sequences (ORFs). See text.

->l

>l

tnpA
tnpB
tnpC
tnpD

elements in a deeply silent condition. The very same mechanism can
also program the elements to be expressed in a precise developmental
pattern, active in certain plant parts but not others. While this
regulatory mechanism has some of the characteristics of more widely
known reversible regulatory mechanisms of bacteria, plants, and
animals, it has the paradoxic quality that it also resembles the more
permanent changes in gene expression produced by mutations. That is,
maize transposable elements are controlled by a genetic mechanism
that is both heritable and reversible. We have studied the regulatory
mechanism of the maize Suppressor-mutator (Spm) transposable
element and present here a summary of our current understanding of
its operation.

Spm is one of two transposable element families that McClintock
discovered and analyzed in great genetic detail. Like other transposable
element families, the Spm family contains fully functional autonomous
elements, called Spm elements, and a host of moderately to severely
disabled relatives dependent on the autonomous elements for mobility.
All autonomous Spm elements are interchangeable genetically; we now
know that they are almost indistinguishable at the DNA sequence level,
as well. Each is a bit more than 8300 base pairs in length and appears at
first glance to be quite simple in organization, containing a single
transcription unit, its unit of genetic expression (Fig. 1). The
transcription unit, which contains the element's coding sequences,
begins close to one end of the element, at a site designated the

EMBRYOLOGY 31

transcription start site in Figure 1, and extends almost all the way to the
other end of the element.

The few hundred base pairs outside the transcription unit consist
of sequences that are very important for Spm transcription and
transposition. The extreme ends comprise inverted repeats of a short
sequence, CACTACAAGAAAA. Terminal inverted repeats (or TIRs)
are the hallmark of most transposable elements. These are the
sequences that demarcate the segment of DNA that transposes: all that
is between them moves with them during a transposition event.
Between the TIRs and the transcription unit are sequences of several
hundred base pairs, which we have designated the subterminal
repetitive regions. These, too, are absolutely essential for transposition
and contain, between them, about 25 copies of a repeated sequence that
is different from the TIR sequence and binds to one of the proteins
coded for by the element, as discussed below. The left subterminal
repetitive region contains the element's promoter, the sequence that
signals when the element's transcription unit is to be read and thus
transcribed into RNA.

But this seemingly simple sequence organization hides
considerable genetic complexity. As seen in Figure 1, after transcription
the primary Spm RNA transcript is cut and reassembled in various
ways by differential RNA splicing, giving rise to sequences that
potentially code for different proteins. The black boxes in the transcript
diagrams in Figure 1 represent the exons, the sequences that remain
after splicing, while the lines represent the parts of the primary
transcript that are removed in splicing. We have identified at least four
transcripts, each assembled by a different pattern of splicing from the
Spm element's single primary transcript; they are designated tnpA,
tnpB, tnpC, and tnpD, in order of increasing size. Depicted at the bottom
of Figure 1 are the four transcripts and their protein-coding sequences
(called open reading frames, or ORFs). (The spliced-out regions are
shown as breaks in the solid boxes representing the transcripts.) Each
complete ORF is represented by an arrow, and the protein each
makes — TnpA, TnpB, TnpC, and TnpD — is indicated. Curiously, two of
the transcripts contain a single ORF, while the others contain two. Each
transcript has one ORF that is unique to it, and it is this unique coding
sequence that bears the transcript's name.

ORFs can code for proteins and therefore might have a function.
Genes are sequences that are known to have a function. To show that an
ORF, or "potential" gene, is truly a gene, it is necessary to determine a
function for the protein, something of a detective task. Knowing that
the Spm family's many crippled, immobile members lack parts of the
Spm ORFs, we suspected that some of the ORFs encode proteins
required to move an Spm element from one chromosomal position to
another. Because there is so much overlap in the coding sequences, we

Nina Fedoroff with members of her laboratory. Sitting, left to right: Elena Georgieva,
Andrea Krumholz, Nina Fedoroff, Amy Atzel, Surabhi Raina. Standing: Ryuji Tsugeki,
Tom Hass, Adam Elhofy, Michael Schlappi, Ramesh Raina, Luca Pellegrini.

could not use natural Spm deletion mutations to identify the genes that
code for proteins required for transposition. We therefore dissected the
four transcripts into their molecular components, isolating each of the
ORFs so that the proteins they encode could be tested individually and
in groups for their participation in transposition. (We devised a
detection system for Spm transposition in tobacco — a plant separated
from maize by a considerable evolutionary distance and devoid of any
DNA segments closely enough related to Spm to supply proteins
capable of mobilizing the Spm element.) Testing each ORF alone, we
found that none of the Spm-encoded proteins could support
transposition on its own. But a combination of TnpA and TnpD was
both necessary and sufficient (perhaps together with additional
resident plant proteins) to promote Spm transposition at a high
frequency. The other proteins, TnpB and TnpC, neither helped nor
hindered transposition, leaving their function a mystery.

Thus we had determined that two of the ORFs code for proteins
that directly participate in transposition. But we suspected from genetic
experiments done many decades ago by McClintock that the Spm
element also has genes that determine whether or not the Spin element
is able to move at all and when in the plant's development it does so. In
particular, McClintock had reported that transposable elements were
occasionally turned off not by a permanent mutation (such as those we
later determined to be large deletions of the element's sequences), but
by a kind of genetic event that is heritable, yet can readily be reversed
under certain circumstances. She made the further intriguing
observation that Spm elements are able to "talk to" each other. That is,
an element that is "on" (active) can reactivate an element that is "off"
(inactive), as long as the two are together within the same nucleus. Yet
the conversation must be maintained at close quarters. Once the active
element is separated from the inactive one when the germ cells divide

EMBRYOLOGY 33

in meiosis, the formerly inactive one relapses into its silent state in
progeny plants.

Some years ago we began to study what it is that turns elements
off. Early in our molecular studies on Spm, we noted that the part of its
sequence just downstream from the transcription start site was very
rich in GC base pairs (Fig. 1), a rather unusual property, and that it
contained many sequences in which the C nucleotides could be
modified by the enzymatic addition of a methyl group. Because we
knew that in other instances the methylation of C nucleotides can alter
whether a DNA sequence is expressed, we asked whether the
inactivation of Spm was associated with increased methylation. We
found that it was, but only in a very restricted region, precisely the
region surrounding the transcription start site. Active elements are
unmethylated in the promoter region just upstream and the GC-rich
region just downstream from the transcription start site, while inactive
elements are methylated in these areas. The more stably and heritably
inactive the Spm element, the greater the extent of C methylation in the
GC-rich sequence downstream from the transcription start site, a
sequence we designated the "downstream control region," or DCR (Fig.

1).

We went on to ask whether the element's regulatory sequences
alone were enough for the methylation and silencing to occur in a plant
cell. The element's regulatory sequences include its promoter, which
lies directly upstream of its transcription start site (and coincides with
the subterminal repetitive region whose repeats bind TnpA), as well as
its GC-rich DCR. We isolated these regulatory sequences for study
simply by attaching them to a "reporter" gene, for which we used a
luciferase gene from a firefly. This is the gene that causes the firefly to
emit light, and the light emission can be used in test-tube reactions to
measure gene activity — that is, the amount of protein that is made
under the direction of a given regulatory sequence. We found that the
element's regulatory sequences became methylated when they were
introduced into plant cells, but only if they included the GC-rich DCR.
Thus the element's regulatory sequences themselves have a propensity
to undergo methylation in plant cells leading to inactivation of the
element by reducing its ability to be transcribed.

But how does an active element awaken a silent one? To answer
this question, we began with cells that contained either a silent,
methylated element or a reporter luciferase gene whose Spm regulatory
sequences had been inactivated and methylated. Into such cells, we
introduced each of the element's coding sequences, expressed from a
strong promoter. The answer was clear: the TnpA-coding sequence and
only the TnpA-coding sequence is required to activate an inactive Spm
element or its inactive promoter. And activation is invariably coupled
with a decrease in methylation. But we also found that, paradoxically,

LA

o

o

r O

Element Methylated
In the absence of ample quantities of TnpA, methyl
groups are attached to promoter and downstream
regions, silencing the element.

o *

f # * o f

I I

O

▼ *

Element Transcribing
As TnpA increases, methylation decreases and
transcription proceeds. Some TnpA binds loosely to
element ends, slightly inhibiting transcription but
preventing further methylation.

O

f o

1

D

*

■ D f

1 i

A o ►

o * A

►

o
o

o

A *

o

o *

Element Stops Transcribing
Element continues transcribing until enough TnpA
has accumulated to saturate both ends.

Element Ready to Transpose
TnpA at either end binds together, bringing the
element into a U shape. Element no longer
transcribes and is ready to transpose.

□ TnpA

A methyl group

Fig. 2. How the protein TnpA encourages transposition by both promoting and
inhibiting transcription.

when the promoter is not methylated, the very same TnpA protein
inhibits its expression. Thus we discovered that a single protein can
have opposite regulatory effects on the same promoter: it represses the
unmethylated promoter, but it activates the methylated promoter.

This observation is perhaps less odd than it might appear at first
glance, because TnpA also plays a role in the transposition process
itself. There are binding sites for TnpA at both element ends, suggesting
that when TnpA binds to those sites, it serves to bring together element
ends for transposition. This probably occurs as the element is actively
expressed and the TnpA concentration builds up, shutting off further
transcription in preparation for transposition. But when an element has
been silenced by methylation, TnpA has the opposite effect, activating
transcription and in some way promoting a decrease in the extent of
methylation.

Thus we have uncovered a molecular mechanism that regulates

EMBRYOLOGY 35

how the Spm element's genes are expressed during a plant's
developmental cycle. Plant genes in general, and Spm sequences in
particular, undergo changes in methylation during the plant's
developmental cycle, and this is reflected in developmental patterns of
Spm expression. Fully active elements override this pattern by virtue of
the ability of TnpA to interfere with and reverse methylation. At the
other extreme, transposable elements can become so extensively
methylated within the GC-rich DCR sequence that even TnpA cannot
reactivate them. Such elements remain silent and do not transpose. We
have given the designation cryptic Spm to such extremely inactive
elements. It is in this cryptic form that transposable elements are
generally maintained in the plant genome. When in this cryptic form,
transposable elements can damage neither plant genes and
chromosomes nor their own genes. Thus the cryptic form is optimal for
the survival of both element and plant.

But why have transposable elements survived through
evolutionary time and in such abundance? Why haven't such
potentially damaging genetic elements been eliminated from genomes?
There are no substantive answers to this question, only speculative
ones. The simplest speculation is that transposable elements have
survived simply because when active, they commonly outreplicate the
genomes within which they reside. But this is true only of active
elements, not their cryptic forms, which replicate with the genome but
remain silent and immune to selective pressure.

A clue that transposable elements might have a positive
evolutionary value lies in the observation that cryptic transposable
elements are activated whenever chromosomes sustain extensive
damage, whether spontaneously, as a consequence of irradiation, or as
a result of the unregulated growth that plant cells experience in tissue
culture. This would seem to suggest that chromosomal damage is
amplified by the activation of transposable elements. But in an
evolutionary context, the genetic changes caused by transposable
elements may be an important source of the new genetic and regulatory
combinations that are the raw material of evolutionary change.

It is increasingly apparent that genetic changes on an evolutionary
time scale are of two types: those that occur at a steady, slow pace with
the passage of time and those that occur episodically, giving rise to
periods of rapid evolutionary change. There may be environmental
triggers of episodic evolution whose primary effect is to increase
temporarily the rate of general genetic damage. Or spikes of genetic
damage may occur spontaneously. Either may be further increased and
directed by the massive activation of cryptic transposable element
families, resulting in periods of both high extinction and rapid
evolutionary change. Since the causal relationship between
chromosome damage and activation of transposable elements is not

36

CARNEGIE INSTITUTION

known, an alternative hypothesis is that widespread activation of
transposable elements is the cause, not the consequence of chromosome
damage. Thus genomes may well harbor their own agents (or
amplifiers) of episodic evolutionary change in the form of cryptic
transposable elements.

Intracellular Movement and Metabolism of Lipids

by Richard E. Pagano

Lipids have long fascinated membrane biologists and physical
chemists because encoded in these "simple" molecules is the
ability to spontaneously form macroscopic, two-dimensional
membrane systems whose very shape and properties depend
exquisitely on the chemical makeup of the individual
components. Recently, interest in lipids among cell
biologists and biochemists has increased due to the
discovery of several classes of lipids which have
profound effects on cell function and to the elegant
description of the low-density lipoprotein (LDL)
transport system and its regulation of cholesterol
metabolism.

The membranes of all eukaryotic cells contain
numerous classes of lipids. It is now well-established
that these various lipids are not randomly distributed
among all intracellular membranes, but rather certain
lipids are enriched in the membranes of particular
organelles. In addition, for some membranes such as
the plasma membrane, which encloses the cell,
different lipid species may be distributed

asymmetrically across the membrane. Since no membrane system
within the cell is able to synthesize all of its lipids, the synthesis,
translocation, and sorting of lipids represent an important set of
problems similar to those encountered in the study of membrane
proteins. This general cell-biological problem of "lipid traffic" recently
acquired added importance with the finding that some lipids which are
restricted to certain intracellular locations play important roles in cell
physiology. Thus, understanding the mechanisms which regulate lipid
traffic and organelle lipid composition are critical to our understanding
of cell function.

One approach for studying these mechanisms involves the use of
fluorescent analogs of intermediate or end products of lipid

•

......

iii

,

'""m% d*M

RsjKSiSi'

Richard Pagano

EMBRYOLOGY 37

metabolism — a technique developed in my laboratory. Appropriate
analogs are synthesized in the laboratory and then introduced into
cultured mammalian cells under defined conditions. Because the
analog molecules are fluorescent, we can observe their distribution in
living cells by high-resolution fluorescence microscopy. Changes in the
distribution of these molecules can then be recorded over time and
correlated with their metabolism, as studied by standard biochemical
methods. In this essay, I highlight results which my colleagues and I
have obtained over the years pertaining to three different pathways for
lipid transport, emphasizing unanswered questions and future
directions.

Movement Along the Secretory Pathway

During the life cycle of a cell, certain substances are packaged into
vesicles which are transported to the cell surface, where they fuse with
the plasma membrane, releasing their contents outside the cell. This
process is referred to as the secretory pathway. Studies of lipid traffic
along the secretory pathway have been made possible using fluorescent
analogs of ceramide1 developed in this laboratory by former fellow
Naomi Lipsky, Ona Martin, and myself. These molecules are vital stains
for the Golgi apparatus, a cellular organelle which plays a central role
in directing protein traffic within cells. When human skin fibroblasts
are treated with BODIPY-ceramide, the Golgi apparatus, surrounding
part of the nucleus of the cell, appears bright orange (Fig. 1). The
fluorescent ceramide analogs are metabolized there to yield the
corresponding fluorescent analogs of sphingomyelin (SM), a major
structural lipid in cells, and to yield a glycolipid, glucosylceramide
(GlcCer). These fluorescent metabolites are then transported from the
Golgi complex to the plasma membrane. In addition to this forward
movement of lipids from the Golgi complex to the plasma membrane,
studies by former postdoctoral fellows Toshi Kobayashi and Peter
Hoffmann further demonstrate that certain fluorescent lipid analogs,
once delivered to the Golgi apparatus, have the potential for retrograde
movement to the endoplasmic reticulum, an organelle made up of
membranes that form a system of tubes and flattened sacs continuous
with the nuclear membrane.

As a result of our studies with fluorescent ceramide analogs, such
analogs have become widely used by cell biologists for (1) vital staining

1 Natural ceramide is used by all animal cells as a building block for the synthesis
of higher-order sphingolipids. We have used two different fluorescent fatty acids to
synthesize various fluorescent lipid analogs. They are
N-[7-(4-nitrobenzo-2-oxa-l,3-diazole)]-6-aminocaproyl- ("NBD"), and
N-[5-(5,7-dimethyl BODIPY)-l-pentanoyl]- ("BODIPY"). The corresponding
ceramide analogs are designated as "NBD-ceramide" and "BODIPY-ceramide."

Fig. 1 . Vital staining of the Golgi apparatus by a fluorescent ceramide. Human skin
fibroblasts were labeled with a BODIPY-ceramide. The fluorescent ceramide and its
metabolites accumulate at the Golgi apparatus, which exhibits bright orange
fluorescence (bright area here), while other intracellular membranes such as the
endoplasmic reticulum and nuclear envelope are weakly stained and exhibit green
fluorescence (shaded area here).

of the Golgi apparatus in many different cell types, (2) visualizing lipid
transport along the secretory pathway, and (3) studying the "sorting" of
lipids to the different plasma membrane domains of polarized cells,
such as hepatocytes and intestinal epithelial cells. This latter
application, pioneered by Gerrit van Meer, Kai Simons, and their
colleagues at the EMBL (Heidelberg), is particularly intriguing because
it shows that NBD-ceramide and its metabolites are recognized by the
cellular sorting and transport machinery in a similar manner to their
natural counterparts.

Studies with fluorescent and non-fluorescent ceramide analogs by
former fellow Tony Futerman demonstrated that the Golgi complex is
the major site of SM and GlcCer synthesis. The enzymes responsible for
this synthesis ("synthases") are restricted to subcompartments of the
Golgi apparatus and may also play essential roles in regulating
intracellular membrane traffic. Indeed, recent work by former fellow
Anne Rosenwald demonstrated that partial inhibition of these enzymes
or elevation of their substrate (ceramide) concentrations dramatically
slows glycoprotein processing and transport to the cell surface. In
addition, current postdoctoral fellow Chii-Shiarng Chen has recently
shown that ceramide can modulate the cell's uptake (or endocytosis) of
various labeled molecules from the external bathing medium.

We are eager to study a number of fundamental cell-biological
questions pertaining to these enzymes. For example, are there different
forms of these synthases with different intracellular locations? How are
they retained in the proper intracellular location(s)? How are their
activities regulated?

In order to address these questions it is first necessary to identify
and purify the SM and GlcCer synthases, and we are using two

EMBRYOLOGY 39

approaches to do so. In a biochemical approach using rat liver Golgi
membranes which are highly enriched in these enzymes, former fellow
Yasushi Kamisaka and current fellow Pascal Paul have developed a
two-step detergent solubilization procedure, followed by a number of
chromatographic steps. To date they have succeeded in purifying each
of the synthases several thousandfold over the starting material. We are
continuing to refine this approach using various additional
chromatography steps. If this biochemical approach is successful, we
will employ standard methods for cloning the genes encoding these
enzymes. We will also make antibodies to the purified proteins to probe
for the existence of multiple forms of these enzymes and to study their
subcellular localization at the electron microscope level.

We are also employing a genetic approach to isolate temperature-
sensitive mutant Chinese hamster ovary (CHO) cells defective in SM or
GlcCer synthase activities, using a replica screening method. We have
designed an in situ assay for SM synthase activity in cells grown on
replicate polyester discs, and experiments are in progress to screen
mutagenized CHO cells for mutants defective in this activity. Following
isolation of such mutants, they will be characterized for defects in lipid
and protein transport, as well as in lipid synthesis.

Recycling of Plasma Membrane Lipids and Transport along the
Endocytic Pathway

During the life cycle of the cell, certain large molecules required for
cell growth are taken up from the bathing medium by a process called
endocytosis. During endocytosis, bits of the plasma membrane fold
inward and eventually pinch off to form small (endocytic) vesicles that
move into the cytoplasm. After delivery of their contents to the cell
interior, empty vesicles can recycle back to the cell surface.

Studies of lipid internalization and recycling were initiated in this
laboratory by former graduate student Mike Koval. The pathway can
be readily visualized using an NBD-labeled analog of SM. During a
low-temperature incubation, this analog is incorporated exclusively
into the plasma membrane of the cells; however, subsequent warming
of the cells for a few minutes at 37°C results in labeling of large
numbers of endocytic vesicles. Recycling of the internalized plasma
membrane lipid is extremely rapid, occurring with a half time of 5-10
minutes at 37°C, while lipid transport to the lysosomes, where
degradation occurs, is a much slower process (half-time 90 min).

Recently Ona Martin and I have been reinvestigating some of these
earlier studies using a BODIPY-labeled SM analog. We showed that
with increasing concentrations in cellular membranes, this fluorescent
lipid exhibits a spectral shift from green to red wavelengths.
Interestingly, we found that some endocytic vesicles exhibited green

Fig. 2. Internalization of a fluorescent
lipid from the plasma membrane.
Human skin fibroblasts were labeled
with a fluorescent (BODIPY) analog of
sphingomyelin at 4°C and (A)
immediately photographed, or (B)
subsequently warmed for 5 min at
37°C prior to observation and
photography. Note the prominent
labeling of the cell surface in (A) and
the presence of numerous fluorescent
endocytic vesicles (shaded areas and
bright spots) scattered throughout the
cytoplasm in (B).

fluorescence while others emitted orange fluorescence (Fig. 2). In
addition, "orange endosomes" were sometimes seen at the edges of
cells. These results suggest that different populations of endosomes
within the same cell may contain different concentrations of the
fluorescent lipid analogs. We are currently testing various models for
transport of the lipid analogs along the endocytic pathway to explain
this striking phenomenon.

We are also trying to isolate mammalian cell mutants which are
defective in lipid uptake or transport. This project is being carried out
by postdoctoral fellow Kentaro Hanada. His basic strategy involves the
use of fluorescent lipid analogs as probes for the selection of such
mutants using a fluorescence-activated cell sorter and replica-
screening techniques. Once a mutant clone is obtained, it should be
possible to determine whether defects in incorporation result from
defects in lipid-uptake mechanisms such as endocytosis, transbilayer
movement, lipid degradation, and/or reutilization of the fluorescent
lipid analog. Eventually we hope to use the strategy of "expression
cloning" of cDNA to complement the defect of fluorescent
lipid-incorporation in the mutant cells, and to attempt to isolate the
gene(s) responsible for the defect.

A Cell Surface Phospholipase and Regulation of Cell Growth

Previous studies from this laboratory by former graduate student

EMBRYOLOGY 41

Tony Ting utilized a fluorescent analog of phosphatidylinositol (PI) to
identify a novel cell-surface phosphatidylinositol-specific
phospholipase C (csPI-PLC) which is present in quiescent Swiss 3T3
cells, a cell line widely used by cell biologists, as well as in a number of
other cell lines which exhibit inhibition of cell growth when the cells
grow and begin to contact one another in culture. When cells are
incubated with the fluorescent PI analog, lipid at the cell surface is
hydrolyzed to fluorescent diacylglycerol. The latter is readily
transported across the plasma membrane and labels various
intracellular membranes, as shown in Figure 3. This activity is not
present in sparse cell cultures nor in cell lines that are tumorigenic
and /or do not exhibit growth inhibition in a density-dependent
manner. Inhibition of csPI-PLC activity results in the stimulation of
DNA synthesis and cell division in confluent Swiss 3T3 cells, providing
further evidence that csPI-PLC plays an important role in cell growth
regulation.

Current research on this project is being carried out by graduate
student Jining Bai, whose efforts are focused on cloning csPI-PLC. He
has designed a cloning strategy specifically for PI-PLCs in Swiss 3T3
cells, and identified three alternatively spliced forms of this enzyme.
Immunofluorescence studies suggest that the three splicing forms are
differentially distributed within cells. Two of them are distributed in
the cytoplasm, while the third appears bound to the plasma membrane.
Studies are in progress to determine whether the latter form is related
to csPI-PLC.

Fig. 3. Results of lipid hydrolysis at the cell surface. Swiss 3T3 cells were incubated
with a fluorescent (NBD) analog of phosphatidylinositol (PI). Biochemical analysis
demonstrated that the fluorescent PI was hydrolyzed to fluorescent diacylglycerol at
the cell surface. The diacylglycerol readily enters the cell at low temperature and labels
the Golgi apparatus, endoplasmic reticulum, mitochondria, and nuclear envelope.

42 CARNEGIE INSTITUTION

In the long term, we hope (1) to learn whether csPI-PLC restores
density-dependent inhibition of cell growth when transfected into cells
which do not exhibit this characteristic, (2) to study the role of this
molecule in the regulation of cell growth, and (3) to explore the possible
role which csPI-PLC may play in vivo in cell differentiation and
development.

Conclusion

While many important details must still be resolved, studies of
lipid traffic in eukaryotic cells have progressed substantially since our
early work in the field and now constitute an important area of
investigation in cell biology. Although we continue to study some of
these details, I believe the stage is now set for the identification and
isolation of the proteins involved in lipid sorting and transport and in
lipid signaling using the powerful tools of molecular biology and
genetics, as outlined in this article. Such information should eventually
lead to an understanding of how the various pathways of intracellular
transport are integrated and regulated.

Short Reports

Donald Brown action in controlling the level of these

Thyroid hormone induces essential receptor molecules,
transformation of every tissue and organ In a collaborative study with Valerie

of the tadpole. It does so by altering the Galton and Donald St. Germain at

expression of groups of genes. We are Dartmouth Medical School, Robert

examining these complex programs by Schwartzman has identified one of the

identifying the multiple genes involved in thyroid hormone-induced genes as a type

causing change in a variety of tissues. Ill deiodinase. This enzyme destroys

These genetic programs result in cell thyroid hormone, and its presence

death, growth, or extensive remodeling. influences the effective concentration of

In the past year Brian Eliceiri has the hormone in a tissue,
completed a quantitative description of The development of the amphibian

the abundance of the thyroid hormone limb depends upon thyroid hormone,

receptor proteins during metamorphosis. Elizabeth Helmer has begun a project to

One form of the receptor accounts for all identify genes that are essential for this

of the molecules capable of binding the process,
hormone — strong evidence that this

receptor molecule plays an essential role Susan Dymecki
in initiating the metamorphic program. A central issue in mammalian

Eliceiri's analysis points out the development — understanding how cell

importance of events that follow gene lineage and environment determine

EMBRYOLOGY

43

phenotype — has been limited by the
inability to follow the fate of specific cells
in the embryo and to observe the
distribution of their progeny cells
throughout gestation. My lab is
generating a transgenic mouse system
that should overcome these limitations.
The initial goal is to use this new tool to
get at mechanisms underlying the
establishment and diversification of
neural crest derivatives. Derangements in
the neural crest are implicated in many
congenital malformations having
devastating neurobiological and cognitive
effects in mammals, including humans. It
is my hope that this work will provide
new approaches to prevention and
treatment of developmental disabilities in
children.

Andrew Fire

Our group seeks to understand how
cells adopt specific fates during
embryonic development. As an
experimental organism, we use the
nematode C. elegans. Small size, a rapid
life cycle, and a variety of genetic tools
allow much more detailed functional and
anatomical analyses with C. elegans than
are possible using vertebrate systems. C.
elegans thus provides a model system of
choice for studies of embryo development.

Formation of specific cell types (e.g.,
muscle, skin, gut) occurs relatively late
during embryonic cell proliferation.
Earlier embryos consist of
undifferentiated progenitor cells that
apparently carry the information to
produce specific patterns of progeny cells.
A molecular approach to pattern
formation entails several questions. (1)
How do cells derived from a single
precursor (the fertilized egg) acquire
unique identities during the early
divisions? (2) What molecules are used to
store early identity information? (3) How
do cells interpret this information to
generate specific tissues?

We have been addressing these

questions using a variety of techniques.
Transgenic technology allows us to
identify rare gene products which are
distributed asymmetrically in early
embryos. These serve as both markers for
early cellular identity and potential
candidates for factors involved in storing
and interpreting pattern information.
Genetic techniques allow us to
characterize the roles of individual
components in the overall program of
embryonic development (by disrupting
the corresponding gene and examining
development in the resulting mutant
embryos). Biochemical approaches have
allowed us to begin working backward
from components produced during
terminal differentiation to identify the
regulatory factors specifying defined
patterns of gene expression. By
combining information from these diverse
approaches, we hope in the next few
years to generate a working model for
development in a simple embryo.

Joseph Gall

The major emphasis of our laboratory
is on the synthesis and processing of RNA
molecules within the nucleus. We are
especially interested in the small nuclear
ribonucleoproteins (snRNPs) that are
essential for processing all other types of
RNA. snRNPs occur in several nuclear
organelles, of which the so-called coiled
body is emerging as one of the most
interesting. We are investigating the
molecular properties of coilin, a protein
located exclusively in coiled bodies, and
we are studying the composition and
assembly of coiled bodies in oocytes and
in vitro. Our studies have led us to
suggest that coiled bodies may play a
pivotal role in the preassembly of
multiple snRNA complexes and their
sorting to the actual sites of RNA
processing in the nucleus.

Douglas Koshland

The process of mitosis can be divided

44

CARNEGIE INSTITUTION

into three phases: the packaging of
replicated chromosomes, their attachment
to the mitotic apparatus, and their
movement apart. Our lab employs
genetic, cytological, and biochemical
methods to elucidate the molecular basis
of each of these phases in the budding
yeast. Our studies have revealed that at
least some of the molecules that mediate
the packaging and movement of
chromosomes are conserved from yeast to
man. In addition, the molecules that
mediate fundamental aspects of mitosis
have been usurped to function in related
cell-biological processes required during
development.

Nipam H. Patel

I am studying the genes that control
pattern formation during the
development of the fruit fly Drosophila
melanogaster, and much of my effort has
concentrated on understanding the role of
the gooseberry gene in the development of
the central nervous system. I have found
that gooseberry, which is a member of a
gene family that encodes a group of
transcription factors, is important in
determining the identity of particular
neurons and in establishing the proper
pattern of axonal connectivity during
development. By looking at homologs of
various Drosophila genes in other insects,
I am also investigating the evolution of
the genes that control Drosophila
segmentation. This analysis will allow us
to understand how complex
developmental processes evolve and how
changes in morphology are related to
changes in gene expression.

Pernille Rorth

During development, cell
differentiation is manifested by selective
gene expression. My work is aimed at
understanding, at the molecular level,
how transcription factors control gene
expression in vivo. I have used a
transgenic rescue assay to determine

which molecular features of DmC/EBP, a
basic region /leucine zipper transcription
factor, are necessary and sufficient for its
essential function during Drosophila
embryogenesis. Surprisingly, the short,
evolutionarily conserved basic region is
solely responsible for specifying DmC/
EBP activity in vivo. I am currently
developing a new type of genetic
interaction screen to identify key gene
products regulating, or regulated by,
DmC/EBP.

Allan Spradling

Eukaryotic genomes contain
substantial amounts of repetitive,
transposon-rich DNA clustered in
chromosome regions known as
heterochromatin. We previously
postulated that some heterochromatic
regions rearrange during development to
activate the few genes located there. This
year, new insight was obtained into the
occurrence of such rearrangements
during Drosophila nurse cell and follicle
cell development. Satellite DNA
sequences become underrepresented
during the first polyploid follicle cell
division, and the Dp 11 87
minichromosome is cleaved at its
euchromatin-heterochromatin junction.
Methods to insert genetically marked P
transposable elements into
heterochromatin were developed that
greatly facilitate the study of these
regions.

Catherine Thompson

I am investigating the molecular
mechanisms underlying development of
the mammalian central nervous system.
Because of the enormous complexity of
the nervous system, I am focusing on a
subset of regulatory events that occur
during a defined period of
development — those that are induced by
thyroid hormone. Thyroid hormone is
essential for the proper development of
the mammalian central nervous system.

EMBRYOLOGY

45

The actions of thyroid hormone are
mediated through nuclear receptor
proteins, which regulate the expression of
specific genes in response to hormone
binding. Until recently, the genes
regulated by thyroid hormone receptors

in the brain were largely unknown. I have
isolated several thyroid hormone-
responsive genes from developing rat
brain, and am analyzing the functional
significance of these genes and the
products they encode.

Bibliography

Reprints of the publications listed below
can be obtained at no charge from the
Department of Embryology, 115 West
University Parkway, Baltimore, MD 21210.

Ahnn, J., and A. Fire, A screen for genetic

loci required for body-wall muscle
development during embryogenesis in C.
elegans, Genetics 137, 483-498, 1994.

Bauer, D. W., C. Murphy, Z. Wu, C.-H. H.

Wu, and J. G. Gall, In vitro assembly of
coiled bodies in Xenopus egg extract, Mol.
Biol. Cell 5, in press.

Brown, D. D., Some genes were isolated

and their structure studied before the
recombinant DNA era, BioEssays 16, 139-
143, 1994.

Brown, S. J., N. H. Patel, and R. E. Denell,

Embryonic expression of the single-
Tribolium engrailed homolog, Dev. Genet.
15, 7-18, 1994.

Bucher, E., and G. Seydoux, Gastrulation

in the nematode Caenorhabditis elegans,
Seminars in Developmental Biology 5, 121-
130, 1994.

Chen, L., M. Krause, M. Sepanski, and A.

Fire, The C. elegans MyoD homolog HLH-
1 is essential for proper muscle function
and complete morphogenesis, Develop-
ment 120, 1631-1641, 1994.

Condron, B. G., N. H. Patel, and K. Zinn,

engrailed controls glial /neuronal cell fate
decisions at the midline of the central
nervous system, Neuron, in press.

Fedoroff, N. V., and V. Chandler, Inac-

tivation of maize transposable elements,
in Homologous Recombination in Plants, J.
Paszkowski, ed., Kluwer Academic Pub-
lishers, Dordrecht, The Netherlands, in
press.

Fedoroff, N. V., DNA methylation and

activity of the maize Spm transposable ele-
ment, in Gene Silencing in Higher Plants and
Related Phenomena in Other Eukaryotes, P.
Meyer, ed., Springer- Verlag, New York, in
press.

Fedoroff, N., Barbara McClintock, Gene-
tics 136, 1-10, 1994.

Fire, A., A four-dimensional digital
image archiving system for cell lineage
tracing and retrospective embryology,
Computer Applications in the Biological
Sciences (CABIOS) 10, 443-447, 1994.

Guacci, V., A. Yamamoto, E. Hogan, and
D. Koshland, Chromosome structure in
budding yeast, Cold Spring Harbor Symp.
Quant. Biol. 58, 677-685, 1993.

Guacci, V., E. Hogan, and D. Koshland,
Chromosome condensation and sister
chromatid pairing in budding yeast, /. Cell
Biol. 125, 517-530, 1994.

Heck, M., A. Pereira, P. Pesavento, Y
Yannoni, A. C. Spradling, and L. S. B.
Goldstein, The kinesin-like protein
KLP61F is essential for mitosis in Dro-
sophila, /. Cell Biol. 123, 665-679, 1993.

Ihrke, G., E. B. Neufeld, T. Meads, M. R.
Shanks, D. Cassio, M. Laurent, T. A.
Schroer, R. E. Pagano, and A. L. Hubbard,
WIF-B cells: an in vitro model for studies
of hepatocyte polarity, /. Cell Biol. 123,
1761-1775, 1993.

Kanamori, A., and D. D. Brown, Cul-
tured cells as a model for amphibian
metamorphosis, Proc. Natl. Acad. Sci. USA
90, 6013-6017, 1993.

Koshland, D., Mitosis: back to the basics,
Cell, in press.

Krause, M., S. White Harrison, S. Xu, L.
Chen, and A. Fire, Elements regulating
cell and stage-specific expression of the C.
elegans MyoD homolog Wh-1, Dev. Biol, in
press.

Lin, H., and A. C. Spradling, Germline
stem cell division and egg chamber
development in transplanted germaria,
Dev. Biol. 159, 140-152, 1993.

Lin, H., L. Yue, and A. C. Spradling, The
Drosophila fusome, a germline specific or-
ganelle, contains membrane skeleton
proteins, and functions in cyst formation,
Development 120, 947-956, 1994.

46

CARNEGIE INSTITUTION

Martin, O. C, and R. E. Pagano, Inter-
nalization and sorting of a fluorescent
analog of glucosylceramide to the Golgi
apparatus of human skin fibroblasts:
utilization of endocytic and non-en-
docytic transport mechanisms, /. Cell Biol.
125, 769-781, 1994.

Mello, C, and A. Fire, DNA transforma-
tion, in Methods in Cell Biology: C. elegans,

D. Shakes and H. Epstein eds., Academic
Press, New York, in press.

Okkema, P., S. White-Harrison, V.
Plunger, A. Aryana, and A. Fire, Sequence
requirements for myosin gene expression
and regulation in C. elegans, Genetics 135,
385^04, 1993.

Okkema, P., and A. Fire, The C. elegans
NK-2 class homeoprotein CEH-22 is in-
volved in combinatorial activation of gene
expression in C. elegans muscle, Develop-
ment, in press.

Pagano, R. E., and O. C. Martin, Use of
fluorescent analogs of ceramide to study
the Golgi apparatus of animal cells, in Cell
Biology: A Laboratory Handbook, J. E. Celis,
ed., Academic Press, New York, in press.

Patel, N. H., Imaging neuronal subsets
and other cell types in whole-mount
Drosophila embryos and larvae using an-
tibody probes, in Methods in Cell Biology,
Vol. 44, Drosophila melanogaster: Practical
Uses in Cell Biology, L. S. B. Goldstein and

E. Fyrberg, eds., Academic Press, New
York, in press.

Patel, N. PL, Evolution of arthropod seg-
menation: insights from comparisons of
gene expression patterns, Development
Suppl, in press.

Patel, N. H., Evolution of insect pattern-
ing, Proc. Natl. Acad. Sci. USA, in press.

Patel, N. H., B. G. Condron, and K. Zinn,
Pair-rule expression patterns of even-
skipped are found in both short and long
germ beetles, Nature 367, 429^34, 1994.

Rosenwald, A. G., and R. E. Pagano, Ef-
fects of glucosphingolipid synthesis in-
hibitor, PDMP, on lysosomes in cultured
cells, /. Lipid Research, in press.

Schlappi, M., R. Raina, and N. Fedoroff,
Epigenetic regulation in the maize Spm
transposable element: novel activation of
a methylated promoter by TnpA, Cell 77,
427^37, 1994.

Scholtz, G., N. H. Patel, and W. Dohle,
Serially homologous engrailed stripes are
generated via different cell lineages in the
germ band of amphipod crustaceans
(Malacostraca, Peracarida), Int. J. Dev.
Biol., in press.

Seydoux, G., and A. Fire, Whole-mount
in situ hybridization for detection of RNA
in C. elegans embryos, in Methods in Cell
Biology: C. elegans, D. Shakes and H.
Epstein eds., Academic Press, New York,
in press.

Seydoux, G., and A. Fire, Soma-germline
asymmetry in the distributions of embry-
onic RNAs in C. elegans, Development, in
press.

Shi, Y -B., and D. D. Brown, The earliest
changes in gene expression in tadpole in-
testine induced by thyroid hormone, /.
Biol. Chem. 268, 20312-20317, 1993.

Spradling, A. C., Position-effect variega-
tion and somatic instability, Cold Spring
Harbor Symp. Quant. Biol. 50, 585-596,
1993.

Strunnikov, A., and D. Koshland, SMC1 :
Yeast gene coding for protein with puta-
tive head-rod-tail organization, essential
for stable chromosome maintenance in
mitosis,/. Cell Biol. 123, 1635-1648, 1993.

Wang, Z., and D. D. Brown, The thyroid
hormone-induced gene expression pro-
gram for amphibian tail resorption, /. Biol.
Chem. 268, 16270-16278, 1993.

Xiong, W. -C., H. Nokano, N. H. Patel, J.
A. Blendy, and C. Montell, repo encodes a
glial-specific homeodomain protein re-
quired in the Drosophila nervous system,
Genes Dm 8, 981-994, 1994.

Zhang, P., and A. C. Spradling, Insertion-
al mutagenesis of Drosophila hetero-
chromatin with single P elements, Proc.
Natl. Acad. Sci. USA 91, 3539-3543, 1994.

Personnel

Research Staff

Donald D. Brown, Director
Nina V. Fedoroff
Andrew Z. Fire

Joseph G. Gall
Douglas E. Koshland
Richard E. Pagano
Allan C. Spradling

EMBRYOLOGY

47

Staff Associates

Susan Dymecki
Nipam Patel
Pernille Rorth1
Catherine Thompson

Postdoctoral Fellows and Associates

Zhou Wang, NIH Grant (Brown)
Chung-Hsiun Wu, Fellow of the Jane Coffin

Childs Memorial Fund
Ayumu Yamamoto, CIW
Ping Zhang, Howard Hughes Research

Associate

Predoctoral Fellows and Associates

Joohong Ahnn, Research Associate, NIH

Grant (Fire)
Amy Atzel, CIW2

Brian Calvi, Fellow, American Cancer Society3
Chii-shiarng Chen, CIW
David Furlow, Fellow of the NIH
Elena Georgieva, Research Associate, NIH

Grant (Fedoroff)
Robert Glaser, Fellow, Markey Charitable

Trust4
Vincent Guacci, Fellow of the NIH
Kentaro Hanada, International Human

Frontier Science Program, NIH Grant

(Pagano)
Elizabeth Helmer, Research Associate,

Mathers Charitable Foundation (Brown)5
Akira Kanamori, Research Associate,

Mathers Charitable Foundation (Brown)
William Kelly, Fellow of the NIH
Linda Keyes, Fellow of the NIH
Mary Lilly, Fellow, American Cancer Society
Haifan Lin, Fellow, Markey Charitable Trust
Jonathan Margolis, Fellow of the NIH
Pamela Meluh, Fellow, The Helen Hay

Whitney Foundation
Mary Montgomery, Research Associate, NIH

Grant (Fire)6
Edward Neufeld, Research Associate, NIH

Grant (Pagano)7
Peter Okkema, Fellow of the NIH
Pascal Paul, Research Associate, NIH Grant

(Pagano)
Luca Pellegrini, Fellow, Consiglio Nazionale

delle Richerche, and CIW8
Ramesh Raina, Research Associate, NIH

Grant (Fedoroff)
Alejandro Sanchez, Research Associate,

Mathers Charitable Foundation2
Michael Schlappi, Fellow, Swiss National

Science Foundation
Lynne Schneider, Fellow of the Jane Coffin

Childs Memorial Fund
Rob Schwartzman, Fellow, American Cancer

Society
Geraldine Seydoux, Fellow, The Helen Hay

Whitney Foundation
David Smith, Research Associate, Markey

Charitable Trust
Alexander Strunnikov, Research Associate,

NIH Grant (Koshland)

Jennifer Abbott, Johns Hopkins University
Jining Bai, Johns Hopkins University
Donna White Bauer, Johns Hopkins

University
Lihsia Chen, Johns Hopkins University
Brian Eliceiri, Johns Hopkins University
Horacio Frydman, Johns Hopkins University
Lina Savage, Anne Arundel Community

College

Supporting Staff

Betty Addison, Laboratory Helper

Kristin Belschner, Photography Assistant

Ellen Cammon, Laboratory Helper

Patricia Cammon, Laboratory Helper

Chelsie Davis, Laboratory Helper

Pat Englar, Administrative Assistant

Eugene Gibson, Custodian

Ken Graf, Technician

Tom Haas, Technician

Stacey Hachenberg, Technician9

Eileen Hogan, Senior Technician

Connie Jewell, Photographer

Glenese Johnson, Laboratory Helper

Jeff Kingsbury, Technician

Bill Kupiec, Computer Systems Manager

Ona Martin, Senior Technician

Keith Menchey, Technician

Ronald Millar, Building Engineer

Christine Murphy, Senior Technician

Christine Norman, Howard Hughes Medical

Institute Research Secretary
Robinette Oliver, Maintenance
Irene Orlov, Technician
Allison Pinder, Technician
Earl Potts, Custodian
Sheri Rakvin, Administrative Assistant
Benjamin Remo, Technician10
Susan Satchell, Business Manager
Michael Sepanski, Electron Microscopy

Technician
Donna Somerville, Laboratory Helper11
Loretta Steffy, Bookkeeper/Clerk
Dianne Stern, Technician
Mary Strem, Technician
Dianne Thompson-Stewart, Senior Technician
Joe Vokroy, Machinist
John Watt, Librarian
Siqun Xu, Technician

48

CARNEGIE INSTITUTION

Visiting Investigators and Collaborators

Eldon Ball, Australian National University,

Australia
Michele Bellini, Laboratoire de Genetique

du Developpement, Paris VI University
Michael Edidin, Department of Biology,

Johns Hopkins University
Zandy Forbes, Department of Zoology,

Oxford University, England
Valerie Galton, Department of Physiology,

Dartmouth Medical School
Phil Hieter, Department of Molecular

Biology and Genetics, Johns Hopkins

School of Medicine
Andrew Hoyt, Department of Biology, Johns

Hopkins University
Ann Hubbard, Department of Cell and

Anatomy, Johns Hopkins School of

Medicine

Michael Krause, National Institutes of Health
Carolyn Machamer, Department of Cell and

Anatomy, Johns Hopkins School of

Medicine
Patrick Masson, Laboratory of Genetics,

University of Wisconsin — Madison
Andrei Mirzabekov, Engelhardt Molecular

Biology Institute, Moscow
Markus Noll, University of Zurich,

Switzerland
Rob Saint, University of Adelaide, Australia
Donald St. Germain, Department of

Physiology, Dartmouth Medical School
Robert Whittier, Mitsui Plant Biotechnology

Research Institute, Tsukuba, Japan
Zheng'an Wu, Institute of Developmental

Biology, Academia Sinica, Beijing
Alexander Tsvetkov, Institute of Cytology,

Russian Academy of Sciences
Kai Zinn, California Institute of Technology

1 From January 1,1994
2From March 14, 1994
3From October 1,1993
4To July 31, 1993
5From December 1, 1993
6From February 1, 1994

7To January 31, 1994
8From March 21, 1994
9From March 16, 1994
10From May 31, 1994
nTo March 31, 1994

Department of Plant Biology

Spinacia oleracea

Members of the Department of Plant Biology, 1994. Front row, left to right: Elena Casey,
Robin Buell, Greg Colello, Anne Blanche Adams, Geeske Joel, Catherine Copass,
Christopher Somerville, Frank Nicholson. Second row: Neil Hoffman, Jim Randerson, Marc
Nishimura, Ruth Alscher, Christiane Nawrath, Julie des Rosier, Jane Edwards, Amie Franklin,
Fitnat Yildiz, Missy Holbrook, Shauna Somerville, Yves Poirier, Cesar Bautista, Dave Fork,
Barbara March. Third row: Seung Rhee, Steven Resier, Melicent Peck, Xingxiang Li, Joe
Ogas, Deane Falcone, Pierre Broun, Claire Granger, Kris Niyogi, Carolyn Malmstrom, Aida
Wells. Fourth row: David Kehoe, Connie Shih, Larry Reid, Tom Berkelman, Michelle Nikoloff,
Wei Fu, Cyril Grivet, John Quisel, Luc Adam, Catharina Lindley. Back row: Brian Welsh,
Glenn Ford, Mary Smith, Arthur Grossman, James Zhang, Olle Bjorkman, Eric Nelson,
Simon Turner, Wayne Stochaj, Pedro Pulido, Howard Whitted, Kirk Apt, Joe Berry, Steve
Lindley, Chris Field, Sunia Yang, Chris Lund, Nadia Dolganov, Mannie Liscum.

The Director's Introduction

The past year in the Department of Plant Biology has been one of
transition. In July 1993, Winslow Briggs retired as director after
twenty years at the helm. During Winslow's tenure the
Department underwent major evolution in the structure of the research
groups, the scope of research, and the dimensions of the physical plant.
Meanwhile, the Department became one of the most highly cited
institutions in the field of plant biology, ranking second only to the
Australian National University. This remarkable achievement reflects,
in part, the uniqueness and central importance of the ground-breaking
research into the physiological mechanisms of plant adaptation for
which the Department is well known. As I now face the task of leading
the Department into the future, I look forward to the challenge of
carrying this legacy forward.

The study of plant biology has undergone a major revolution
during the past decade and is currently enjoying what could be called a
Golden Age. A major stimulus was the widespread application of the
techniques of molecular genetics to problems in plant biology. The
enthusiasm with which plant biologists adopted the new paradigm was
so complete that disciplines in the plant sciences such as physiology
and biochemistry have been substantially depopulated. On the other
hand, disciplines such as plant morphology, which had become
relatively moribund, have been reinvigorated by the growth of interest
in developmental biology, and legions of students are once more
interested in being able to identify and name tissues and organs.

The widespread adoption of Arabidopsis thaliana as a model species
and the accompanying growth of interest in genetic methods have also
greatly accelerated progress toward the resolution of many
long-standing problems in plant biology. Genes encoding the proteins

51

-*:;*«slljii»

The Department's new addition, completed in early 1993.

that regulate many aspects of growth and development have been
characterized by exploiting the genetic advantages of Arabidopsis, and
it is increasingly difficult to find an aspect of plant biology that is not
being intensively dissected in this model plant by one or more
laboratories. For a variety of reasons, the average size of plant biology
laboratories has also increased substantially in recent years; research
groups consisting of fifteen or more postdoctoral fellows and students
are not uncommon. It has been estimated that as many as 2,000
scientists worldwide are now using Arabidopsis as a primary
experimental organism, and many thousands more work with other
species. More than 9,000 Arabidopsis genes and at least 12,000 rice
genes have been partially or completely sequenced, and the first
tentative steps have been taken toward the complete sequencing of the
genomic DNA of Arabidopsis. It now seems likely that this first
complete sequence of a plant genome will be available shortly after the
turn of the century, and that the primary function of many of the genes
will be known by that time.

What, then, is the role of a Carnegie Department of Plant Biology in
the midst of this tremendous amount of activity and discovery? I
believe the answer is the same as it has always been within Carnegie:
We will invest in exceptional individuals and provide these individuals
with the freedom, the time, and the resources to make discoveries
wherever they may find them. In the current climate of strenuous
competition for limited resources, the simplicity of the Carnegie
approach to supporting research is as valuable and unique as at any
time in the past. The diversity of research interests represented by the
Department of Plant Biology staff ensures the Department's
participation in many of the major themes of modern plant biology,
from global ecology to plant molecular biology.

The following two essays outline some of the new research
directions within the Department which have resulted from the
appointments of Shauna Somerville and me as new staff members.

PLANT BIOLOGY 53

Shauna's interests concern the molecular basis of the mechanisms by
which plants sense infection by fungal and bacterial pathogens and
mount defensive responses. Since it is harmful to the fitness of the
pathogen for the host to trigger a defensive response, and harmful to
the host not to detect the pathogen, the pairs of organisms are locked in
a complex pattern of coevolution in which host resistance genes are
paired with pathogen virulence genes. The molecular basis for the high
degree of specificity in the host-pathogen interactions is not known.
However, a working hypothesis is that the plant resistance genes
encode membrane receptors which intercept signals from pathogens
and trigger cellular defense responses. In this respect, the closest analog
for the phenomenon in animals is probably the human-leucocyte-
associated (HLA) system that causes rejection of transplanted tissues.
Shauna's long-term goal is to identify the host factors that mediate the
specificity of the interaction between the obligate fungal pathogen
Erysiphe cruciferarum (powdery mildew) and Arabidopsis. Because so
little is known about the molecular mechanisms underlying any plant
pathogen interaction, I consider this to be one of the areas of greatest
scientific opportunity in plant biology.

The second essay describes several aspects of my own research
program on mechanisms that regulate membrane lipid composition. I
was attracted to the area because we do not know the answer to many
fundamental questions such as why plant or animal membranes are
composed of so many different species of lipids; we do not know how
the composition of the membranes is regulated, nor what regulates the
amount of a particular membrane. Also, in spite of thousands of
correlative studies suggesting a role for membrane composition in
temperature acclimation, no direct test had been done by exploiting the
power of modern genetics to create organisms differing by only one
gene. We now have the genetic materials to complete such tests, in
collaboration with DPB staff member Olle Bjorkman. Because plant
lipids are also an important and chemically versatile source of
biomaterials, I have also been attracted by the prospect of using genetic
engineering methods to produce plant oils having nutritionally
improved qualities or new industrial uses that could reduce our
reliance on non-renewable resources. Our goals in this respect are to
solve the basic biological problems that currently discourage industrial
research and development in this area.

In addition to these two projects, the fourteen students and
postdoctoral fellows and associates who have joined Shauna and me at
Carnegie each harbor a wealth of curiosity and ideas that we hope to
nurture and develop in this unique scientific setting.

— Chris Somerville

54

CARNEGIE INSTITUTION

Molecular Mechanisms of Plant
Disease Resistance

by Shauna Somerville

Higher plants are susceptible to destructive infections by a wide
variety of viral, bacterial, fungal, and nematode species. Plants
also can participate in a number of benign and beneficial interactions
with microbes. A central concept in plant pathology is that plants have
evolved a set of sensing mechanisms that permit them to recognize and
respond to pathogens. These mechanisms appear to be highly specific
and selective, in that a large number of disease-resistance genes have
been described where each gene confers resistance to
one species or, in some cases, to one race of pathogen.
My research program is focused on understanding the
molecular mechanisms underlying the recognition of
pathogens by plants.

The development of an incompatible plant-
pathogen interaction (i.e., resistance to infection) is
thought to involve three steps: (1) the generation of a
signal indicative of attack by a specific race of pathogen,
(2) recognition of the signal by the host, and (3)
transduction of the signal to the cell interior, redirecting
gene expression toward defensive responses. In
susceptible plants, some aspect of this sequence fails, and
a compatible relationship (i.e., infection) is established.

Host resistance genes are thought to participate in
steps 2 and 3. In some cases, recognition can be very selective, a given
allele* conferring resistance to a specific pathogen race. For some
diseases, as many as a hundred pathogen races have been described,
and similar allelic diversity for resistance is found in the host. This
pattern of interaction is characteristic of plant diseases described by the
"gene-for-gene" hypothesis, first proposed in 1955, which states that
incompatible interactions and the expression of resistance develop
when a host plant carrying a resistance allele recognizes a pathogen

Shauna Somerville

*A gene is a sequence of DN A or RNA that when expressed codes for the
manufacture of a specific protein. Expression usually entails transcription of the
gene DNA into complementary RNA and translation of the RNA into protein.

An allele is a version of a gene. Its sequence differs in a few nucleotides from other
alleles of the same gene. Unless self-fertilized, an individual plant has two alleles of
each gene, one from each parent. Among many individual plants, there might be
several or even many alleles of a given gene, a condition of allelic (or genetic)
diversity.

A locus is the region of a chromosome where a given gene is usually situated. A
locus has the same name as the gene usually present there.

Fig. 1 . Scanning electron micrograph of a conidium of Erysiphe graminis f. sp.
hordeion a barley leaf surface. The invader's conidium (en), or spore, has
germinated to produce a primary germ tube (pgt) and an appressorium (ap). A
penetration peg arises from the underside of the appressorium and attempts to
penetrate the plant epidermal cell wall. In this incompatible interaction, the first
penetration attempt was unsuccessful and a second attempt was made, as indicated
by the presence of two penetration-peg lobes (arrowheads) on the appressorium.
Bar= 10|!tn.

having a specific, complementary avirulence allele. In a common
mechanistic model of the "gene-for-gene" hypothesis, disease-
resistance genes encode receptor proteins that intercept a pathogen
signal and activate defensive responses. Thus, characterization of a
resistance gene in the laboratory is an important step in determining a
key biochemical component of disease resistance. In addition, the
genetic structure of resistance loci will dictate the range of novel
resistance alleles that can be created in vitro for the purposes of
genetically engineering stable disease resistance.

Our immediate goals are to identify and characterize plant genes
that confer resistance to the fungal pathogen powdery mildew (Erysiphe
sp.) and to the bacterial black rot pathogen (Xanthomonas campestris pv.
campestris). Powdery mildew disease is characterized by a high degree
of specificity in interactions between barley cultivars and races of E.
graminis (Fig. 1). Because of the many technical advantages and
resources associated with Arabidopsis, we are also pursuing powdery
mildew resistance genes in this model plant species. We anticipate that
powdery mildew resistance genes from Arabidopsis will provide a
technical bridge to homologous genes from the economically important
cereal crops.

Powdery mildew and black rot provide two contrasting examples
of host-pathogen interactions. Whereas resistance in powdery mildew
is associated with a reduction in pathogen proliferation, resistance to
the black rot disease of Arabidopsis is correlated with a reduction in

56 CARNEGIE INSTITUTION

disease symptoms but not in bacterial growth. Reduced symptoms are
sometimes not accompanied by arrested pathogen multiplication; in
such cases, Arabidopsis tolerates the pathogen. In the context of the
"gene-for-gene" model, it will be interesting to compare the
Arabidopsis gene that confers tolerance to X. c. campestris to powdery
mildew resistance genes from barley and Arabidopsis.

Characterization of the Barley Ml-a Powdery Mildew Resistance Locus

The specific barley powdery mildew resistance locus that we have
chosen to study, the Ml-a locus, is highly polymorphic: more than thirty
resistance alleles have been described at this locus. Thus, in addition to
helping us understand the nature of pathogen recognition in barley, the
cloned Ml-a gene will allow us to address the genetic basis for the high
degree of polymorphism at this locus.

We are currently exploring the feasibility of using subtractive
hybridization for cloning the Ml-a gene, a gene for which we lack any
biochemical or structural information. The method, described in
Carnegie Year Book 92 by Catherine Thompson, is based on the
subtraction of sequences from a wild-type (target) DNA, by applying
DNA from a mutant (driver DNA) which lacks certain sequences;
sequences present only in the wild type are recovered. We have
prepared driver cDNA from coleoptiles of five supposed deletion
mutants that presumably lack Ml-a gene sequences. These susceptible
mutants are part of a collection of 35 such mutants isolated from
120,000 seedlings exposed to mutagenesis. We have also made target
cDNA from AlgR, the resistant wild type. In several of our
independently derived pools, the same cDNA was isolated by our
subtraction procedure, suggesting that certain classes of cDNA may not
subtract well, perhaps due to their structural properties. Some of our
cDNAs were derived from mRNAs that varied in expression: some
were apparently coleoptile-specific and were highly expressed, while
others were expressed at low levels in coleoptiles and not expressed in
the RNA from shoots.

Our analysis is continuing, emphasizing mRNAs that are
expressed at low levels in coleoptile tissue. Once candidate Ml-a
cDNAs have been recovered, it will be necessary to determine which of
the cDNA clones encodes the Ml-a locus. The definitive proof will be to
determine which clones are able to confer powdery mildew resistance
to susceptible barley plants.

Map-Based Cloning of Powdery Mildew Resistance in Arabidopsis

Barley is an important crop species, and a large number of
powdery mildew resistance alleles have been identified by plant

PLANT BIOLOGY 57

breeders during the past fifty years. Because Arabidopsis is a weed of
no utility, genetic variability for disease resistance is only now being
studied. As a first step in characterizing the powdery mildew disease of
Arabidopsis, caused by Erysiphe cruciferarum, we surveyed fifty
Arabidopsis varieties, or ecotypes, for susceptibility to one isolate of E.
cruciferarum. Six ecotypes exhibited various degrees of resistance and
were retained for further study.

Disease resistance in four ecotypes was conferred by the presence
of a semi-dominant allele at a single, nuclear locus. In one case,
mapping studies placed the resistance locus on chromosome 3, and we
are seeking the resistance loci in the other ecotypes. With ecotypes Te-0
and Sl-0, first-generation progeny were susceptible to powdery
mildew, suggesting that, unlike most resistance genes, resistance in
these two ecotypes was recessive in nature. In the Te-0 second
generation, the ratio 3 susceptible : 1 resistant indicated a one-gene
model. In the Sl-0 second generation, the ratio 9 susceptible : 6
intermediate : 1 resistant indicated that two genes are involved.
Resistance in Sl-0 is unusual, and its analysis may provide a
perspective on resistance genes from weedy species not previously seen
in the more commonly studied genes from crop species.

To recover clones for these resistance genes, we will pursue a
map-based cloning strategy, one recently used in Chris Somerville's
laboratory to isolate Arabidopsis desaturase genes. In brief, molecular
markers lying adjacent to a disease-resistance gene will be used to
identify large fragments of Arabidopsis DNA, cloned as yeast artificial
chromosomes (YACs). The YAC clones, containing the resistance gene
among other genes, will be fragmented into pieces containing only one
or a few genes, and each fragment will be introduced separately into
susceptible Arabidopsis plants. The specific fragment containing the
resistance gene will be identified by a resulting change to powdery
mildew resistance in transformed plants.

Molecular Characterization of Tolerance of Arabidopsis to Black Rot

Using the same approach for characterizing disease-resistance
genes, we have identified black-rot-resistant ecotypes of Arabidopsis.
One ecotype, Columbia, remains asymptomatic even after we infiltrate
black rot bacteria into the intercellular leaf space. By contrast, in the
susceptible ecotype Pr-0, disease symptoms are observed 3-4 days after
inoculation. Interestingly, bacterial multiplication in both the resistant
and the susceptible ecotypes is similar, suggesting that Columbia is
tolerant to high population levels of X. c. campestris. Genetic analyses of
crosses between Columbia and Pr-0 indicated that a dominant allele of
a single nuclear gene, RXC1, governs tolerance to X. c. campestris 2D520.
We have genetically mapped RXC1 to a small interval of chromosome

58 CARNEGIE INSTITUTION

2. In future experiments, this gene will be cloned using map-based
cloning techniques as outlined above.

In a series of experiments focused on understanding the potential
mechanism(s) by which Columbia is able to tolerate X. c. campestris
growth, we examined mRNA levels of various genes proposed to have
a role in defense responses in other systems and /or signaling of stress
events. Inoculation with X. c. campestris 2D520 induced at least a
twofold increase in mRNA levels of several enzymes associated with
disease-resistant genes over that following buffer treatment. We
observed no temporal or quantitative differences in mRNA levels
among tolerant (Columbia) and susceptible ecotypes. Meanwhile
neither Columbia nor the susceptible ecotypes exhibited significant
increases in several other mRNAs associated with disease resistance,
including the ELI3 plant defense gene mRNA. These data indicate that
the defense-response genes analyzed here do not have a substantial role
in the establishment of tolerance to X. c. campestris 2D520 in Columbia.
Thus, although we do not understand the molecular basis for the
effects, tolerance and resistance are distinct mechanisms for limiting
disease in plants.

Conclusion

The isolation of plant disease-resistance genes will resolve the
question how plants recognize and respond to specific pathogens but
not to symbiotic organisms. The first insights into the biochemical
distinction between resistance and tolerance genes will arise from
comparisons among cloned resistance genes. Additionally, fresh
inquiry into the nature and evolution of resistance genes can be
initiated. For example, what is the basis for the highly polymorphic
nature of resistance loci like Ml-a? What impact does this high degree of
polymorphism have on the function of the Ml-a gene product? Does
each powdery mildew resistance gene confer resistance by a unique
mechanism? Are common resistance mechanisms employed against
viral, bacterial, fungal, and nematode pathogens? Meanwhile, sequence
comparisons will provide insights into the extent of conservation or
divergence in the evolution of resistance mechanisms among a broad
array of plant species. In particular, it will be of interest to compare
resistance genes recovered from weedy species, like Arabidopsis, with
crop species, like barley, that have been under cultivation for more than
10,000 years.*

^Portions of the work described in this report have been supported by
the National Science Foundation, the U.S. Department of Agriculture, and
the U.S. Department of Energy.

PLANT BIOLOGY

59

The Role of Membrane Lipid Composition

by Chris Somerville

Along-standing interest in my laboratory is the role of membrane
lipid composition in the ability of higher plants to withstand
temperature stress. Many higher plants are subjected to wide seasonal
variation in temperature and may experience temperature-induced
injury at both extremes. For instance, many plants of tropical origin are
injured by exposure to low, non-freezing temperatures that do not harm
plants from temperate zones (Fig. 1). The existence of regulated adaptive
mechanisms that can protect plants against the harmful effects of
temperature extremes is evident in the ability of some plants to acclimate
to survive exposure to freezing if first given a period of gradual exposure
to low temperature. Similarly, if given a period of growth in progressively
warmer conditions, many species acclimate to thermal extremes that
would injure non-acclimated plants. A large body of correlative evidence
has accumulated from comparative physiological studies that implicates
membrane lipid composition as a component of such temperature-
tolerance mechanisms. Much of the focus has been on the degree to which
the fatty acyl chains of the lipids are saturated. In a saturated fatty acid,
each of the carbon molecules within the acyl chain are bonded to two
hydrogen molecules. This allows the lipids to be packed very tightly
together, resulting in a membrane with relatively solid composition. Butter
is a familiar example of a substance containing a high proportion of
saturated fatty acids. The introduction of double bonds into the acyl

Fig. 1 . The effect of two days of exposure to 4°C on chilling-sensitive squash
plants. The plant on the right was left at 23°C.

60 CARNEGIE INSTITUTION

chains, referred to as desaturation, forces the fatty acids apart so that the
membranes become more fluid. The vegetable oil used for cooking is
liquid at room temperature because the fatty acids in its lipid membranes
contain one or more double bonds.

In order to directly test the role of membrane lipid fatty acid
desaturation in temperature acclimation and other physiological
responses, we are engaged in characterizing fatty acid desaturases so
that we can create genetically modified plants with defined membrane
lipid composition.

Biochemistry of Desaturases

Plant, fungal, and animal fatty acid desaturases are integral
membrane proteins that, with very few exceptions, have proven
difficult or impossible to purify and characterize. When we began
biochemical studies of these enzymes, the only known exception was
the stearoyl-ACP desaturase from higher plants, a soluble chloroplast
enzyme that introduces the first double bond into saturated fatty acids.
We purified this enzyme from avocado fruits by conventional
chromatographic methods, cloned the corresponding gene from castor,
and obtained high levels of expression of the functional protein in E.
coli. This, in turn, permitted the production of diffracting crystals,
which are being used to determine the structure of the protein by
Gunther Schneider and colleagues (Swedish Agricultural University,
Uppsala). The gene has also been used to isolate two structurally
similar desaturases from distantly related plant species. (These place
the first double bond at different positions in the acyl chain.) When the
three-dimensional structure of the castor stearoyl-ACP desaturase is
completed, it should be possible to generate three-dimensional
structures for the other two related desaturases by computational
methods. Then, by comparing the three similar enzymes, it may be
possible to determine how the enzymes position the insertion of a
double bond.

In a second use of the recombinant stearoyl-ACP desaturase, E. coli
production of the recombinant protein in iron-supplemented media
permitted the purification of large amounts of enzyme in which the
active-site iron was isotopically enriched. Mossbauer spectrometry of
the labeled protein, carried out in collaboration with Brian Fox and
Eckhardt Miinck (Carnegie Mellon University), indicated the presence
at the active site of two iron molecules that were linked by an oxygen
molecule. A similarly structured iron site has previously been observed
in several other proteins, most notably in methane monoxygenase. The
presence of this site suggested an explanation for several features of
desaturases known from studies of the vertebrate enzyme by Phillip
Strittmatter and colleagues, and permitted the formulation of a

PLANT BIOLOGY 61

hypothetical reaction cycle for this important class of enzymes.
Although additional experiments are required to critically test the
proposed cycle, it is apparent that many of the previously intractable
problems associated with understanding the structure and function of
desaturases have been overcome by selecting a suitable model.

A prediction of the above proposed cycle is that a relatively small
change in the disposition of a proton during the reaction might convert
a desaturase into an enzyme (a hydroxylase) that adds an OH group to
the fatty acid rather than inserting a double bond. On the basis of this
idea we searched for and found a structurally divergent
"desaturase-like" gene in Ricinus communis, a plant species that
accumulates large quantities of hydroxylated fatty acids, and
demonstrated that the gene encoded an active hydroxylase when
expressed in transgenic tobacco plants. The discovery of this gene will
permit the development of genetically engineered plants that produce
novel hydroxylated fatty acids that cannot currently be produced in
agricultural species. Such compounds have many technical uses, which
range from direct use in hydraulic fluids and aviation lubricants to use
as precursors for synthesis of nylon and other polymers.

Genetic Studies

In contrast to the stearoyl-ACP desaturase and homologs, all other
desaturases are membrane-bound such that in most cases enzyme
activity cannot be detected by in vitro enzyme assays. Therefore, we
tested the possibility that the structure and function of these enzymes
could be deduced by primarily genetic methods. Diploid plant species,
such as Arabidopsis thaliana, can be mutagenized at very high rates with
chemical mutagens, so that it is frequently possible to identify mutants
lacking activity for any dispensable gene product by screening only a
few thousand individuals. In addition, the recent development of
methods for isolating Arabidopsis genes by chromosome walking
affords an opportunity to exploit the mutations both for comparative
physiological analysis and also for cloning of genes that are only
known by their mutant phenotype and are not accessible by other
approaches.

Mutants affecting fatty acid metabolism were isolated by simply
taking small samples of leaf material or seed from randomly chosen
plants in a mutagenized population and measuring the fatty acid
composition by gas chromatography. By screening approximately
10,000 individuals, seven classes of mutants (designated fadl to fadS)
having defects in fatty acid desaturation were recovered, as well as a
number of mutations that caused other alterations in membrane
composition. None of the mutants could be readily distinguished from
the wild type by visual inspection under normal growth conditions.

■HRi;

Chris Somerville (left) and postdoctoral associates Christiane Nawrath and
Yves Poirier with Arabidopsis plants.

Because it has not been possible to detect activity for most of the
desaturases in vitro, very little was known beforehand about the
number of desaturases, their chemistry, or their cellular localization.
Except for the stearoyl-ACP desaturase, for which no mutation was
recovered, we identified mutations in all the known desaturases in
Arabidopsis. In general, the mutations have metabolic consequences
that are similar to simple blocks in a biosynthetic pathway; the
precursor accumulates at the expense of the product. Analysis of the
effects of each of the fad mutations on the composition of the various
lipids led to our formulation of an overall scheme for the pathway of
lipid unsaturation in plants (see Science 252: 8087, 1991).

As a first step in the isolation of the corresponding genes, all of the
fad mutations were genetically mapped. 7hefad3 gene mapped near a
previously known restriction fragment length polymorphism (RFLP).
The RFLP was used to isolate a relatively large clone of the
corresponding region of the chromosome from an Arabidopsis genomic
library we had previously constructed in a yeast artificial chromosome
(YAC) vector. The YAC clone was then used to isolate cDNA clones for
all the expressed genes in the region of the chromosome covered by the
YAC. One of the cDNAs was found to be highly expressed in
developing seeds — a characteristic we anticipated because of the high
oil content of Arabidopsis seeds. This clone was then used to
genetically complement the fad3 mutation, thereby establishing its
identity. The fad3 gene thus became the first plant gene to be isolated by
map-based cloning methods. The cloning of this gene signaled a new
phase in plant biology in which any gene that can be marked by a
mutation can be isolated without knowing any property of the gene or
its product.

Following the isolation of the fad3 gene, we used the gene as a
heterologous hybridization probe to isolate a number of related genes
(i.e., fad6, fadl , fadS). The function of these homologous genes was

PLANT BIOLOGY 63

established by mapping the cloned genes relative to the map location of
the various fad mutations, then using the cloned genes to genetically
complement the corresponding mutations. In addition, my principal
collaborators, John Browse and his colleagues (Washington State
University), used insertional mutagenesis to isolate the fad! gene,
which we had failed to identify by heterologous hybridization. Thus,
we have isolated genes for most of the eight enzymes that control
membrane fatty acid composition. The genes are currently being used
to examine the role of transcriptional regulation in controlling
membrane composition. The genes have also been used by colleagues
in industry to isolate the corresponding genes from crop species. These
have been used to engineer improvements in the nutritional quality of
edible oils, which comprise approximately one third of the calories in
the diet of the developed world and are factors in heart disease and
other diet-related syndromes.

The Physiological Role of Lipid Unsaturation

The availability of mutants having specific alterations in membrane
lipid fatty acid composition provides a relatively direct method for
examining the physiological consequences of variation in lipid
unsaturation. Because of the availability of a variety of sensitive
techniques for assaying the function of the photosynthetic electron
transport activity of chloroplast membranes, we have initially focused
on the analysis of those mutants that affect chloroplast lipid
composition. Compared to membranes from other organelles,
chloroplast membranes are highly unsaturated. Unexpectedly, the
relatively large changes in lipid unsaturation in the fad mutants had
only minor effects on the rate of photosynthetic electron transport
under any of the conditions examined. This contrasts with the results of
a variety of studies based on less-specific methods, such as inhibitors of
fatty acid unsaturation, lipase treatment, or other correlative
approaches, which had generally suggested an essential role for
unsaturation in supporting the light reactions of photosynthesis.

The most pronounced consequence of decreased lipid unsaturation
was observed in studies of the effects of prolonged exposure of the
mutants to low temperature. When illuminated at 4°C, the wild type
remained green and healthy and continued to grow. In contrast, tissue
of the fad5 and fad6 mutants that developed at low temperature became
chlorotic (yellowed) and the plants exhibited a 30-40% reduction in
growth rate relative to the wild type. In dividing or growing cells, the
chloroplast membranes from the mutants exhibited major structural
abnormalities. In the case of the fad6 mutant, there was only about 25%
as much chloroplast membrane as in the wild type. But the structure of
chloroplast membranes was relatively normal in cells of mutants that

64 CARNEGIE INSTITUTION

were fully grown before exposure to low temperature. Thus, it appears
that the mutants are defective mainly in the biogenesis of new
membrane at low temperature. Chloroplast membranes from the
chlorotic tissues of mutant plants grown at low temperature have
substantial changes in the polypeptide composition, suggesting that
decreased unsaturation impedes protein translocation into chloroplast
membranes. (Various effects of the mutations on chloroplast structure
at normal growth temperature may reflect a general requirement for a
certain degree of lipid unsaturation to accommodate the post-
translational insertion of proteins into chloroplast membranes, rather
than a direct effect of lipid unsaturation on structure.) Whatever the
precise basis for the effects, these results provided direct evidence for a
requirement for membrane polyunsaturation in low-temperature
fitness.

Preliminary evidence indicates that lipid unsaturation is also a
component of thermal (i.e., high-temperature) tolerance. Steady-state
fluorescence measurements of the temperature at which the chlorophyll
a/b binding protein complex dissociated from the photosynthetic
reaction centers in the fad5 and fad6 mutants indicated significant
enhancement of the stability of the chloroplast membranes at high
temperatures. Also, whole-chain photosynthetic electron transport was
less susceptible to thermal denaturation in the mutants. It is
particularly noteworthy that there is a direct correlation between the
degree of chlorosis caused by the various mutations at low temperature
and the degree of thermal tolerance. Thus, it appears that the decreased
unsaturation has effectively shifted the temperature range upward.
Indeed, in short-term growth tests, the fad5 mutant had a substantially
higher growth rate than the wild type at the highest temperatures
tested, suggesting that chloroplast membrane stability is a component
of whole-plant thermal tolerance. Collaborative studies of the thermal
tolerance of these mutants is now under way with colleagues in the
Department of Plant Biology. In addition, the availability of the cloned
desaturase genes will facilitate the genetic modification of membrane
composition and the analysis of phenotypic effects in other plant
species.

Short Reports

Kris Niyogi: Acclimation of Chlamydomonas reinhardtii that are

Photosynthetic Organisms to Light deficient in nonphotochemical quenching.

Quantity Such mutants may have an altered

I am working jointly with Art xanthophyll cycle, which is thought to be

Grossman and Olle Bjorkman to generate important for plants to survive high light

mutants of the unicellular alga levels. We have used a video-imaging

PLANT BIOLOGY

65

system that detects chlorophyll
fluorescence to isolate strains having
either higher or lower levels of
nonphotochemical quenching. We have
also generated several high-light-
sensitive mutants which may have
damage in mechanisms of
photoprotection or photodamage repair.
Our mutagenesis procedure generates
mutants via insertion of a piece of defined
DNA, thereby marking the gene of
interest and allowing for its rapid
isolation. The information that we obtain
from analysis of the mutants should
apply to high-light acclimation in higher
plants, since the photosynthetic apparatus
of Chlamydomonas is virtually identical
to that of higher plants. We anticipate that
the mutants will have alterations in genes
involved in quenching excess light energy
(e.g., xanthophyll-cycle components), in
degradation of damaged reaction center
proteins, in repair of the reaction centers,
and in scavenging and eliminating free
radicals generated by excited chlorophyll
molecules.

Art Grossman: A High-Light-
Inducible Protein

Technical associate Nadia Dolganov
and visiting professor Devaki Bhaya have
isolated and characterized a gene from
the prokaryotic cyanobacterium
Synechococcus sp. Strain PCC 7942 that
encodes a protein of 72 amino acids. The
work is interesting from two perspectives.
First, the protein encoded by this gene
(gene designated hliA and protein
designated HLIP, for high-light-inducible
protein) has strong homology to the
extended family of eukaryotic chlorophyll
a,b binding (Cab) proteins. However, it
only has a single membrane-spanning
helix, while the Cab proteins and the
related early-light-inducible proteins
(ELIPs) of higher plants have three
membrane-spanning helices. Hence, the
HLIP may represent an evolutionary
progenitor of the eukaryotic members of

the Cab extended gene family. Second, we
have recently shown that hliA gene
expression is induced by high light, UV-A
radiation, and, to some extent, by blue
light. The genes for the ELIPs are induced
under similar conditions of illumination
and have been implicated in the
responses of plants to light stress and
recovery from photoinhibition. While we
are exploring the subcellular location and
function of HLIP, we have also developed
a genetic screen to define factors
(including the UV-A /blue-light
photoreceptor and elements that regulate
transcription) that are involved in
modulating the expression of hliA.

Joe Berry: Modeling Ecosystem-
Climate Interactions

During the past year my group
participated in the Boreal Ecosystem
Atmosphere Experiment (BOREAS). This
is a large-scale multidisciplinary study
conducted in northern Canada. The goal
of the experiment is to characterize the
influence of boreal forest ecosystems on
the atmosphere, to understand the
mechanisms that control this, and to
develop algorithms to use satellite remote
sensing to expand these studies to the
global scale. Our role in these studies is to
study the photosynthetic properties of
boreal forest trees and to develop and test
models used to simulate these processes.
The most remarkable result to date is that
photosynthesis and transpiration of
conifer forests are strongly inhibited on
clear sunny days. We have obtained
evidence that this mid-day stomatal
closure is caused by atmospheric
humidity rather than water stress.

Work has progressed on a
land-surface parameterization for climate
models. This year we have conducted
tests of the model with data collected at a
site in a tall-grass prairie in Kansas. This
data set provides observations of climate,
surface exchanges of heat, water vapor,
and CO2 at several sites over the course of

Tower, above, was built for the BOREAS project
to accomodate instruments for measuring
C02/methane/ heat/water vapor exchange
between forest and atmosphere.

CARNEGIE INSTITUTION

cytoplasmic protein that functions in
transport of proteins into the endoplasmic
reticulum. We have been investigating
whether the chloroplast protein, 54CP,
plays a role in the transport of proteins
within the chloroplast.

At least four types of transport
pathways appear to operate in the
chloroplast. One of the transport
pathways is utilized by the
light-harvesting proteins (LHCP) for
integration into the thylakoid membrane.
Light-harvesting proteins are
hydrophobic proteins that have multiple
membrane-spanning regions. Recent
results obtained in collaboration with the
laboratory of Ken Cline (University of
Florida) indicate that 54CP participates in
the integration of LHCP into the
thylakoid membrane. We are currently
testing the hypothesis that 54CP is an
essential component of the machinery
required for the transport of hydrophobic
chloroplast proteins.

a year. The fluxes are controlled primarily
by the seasonal changes in vegetation
cover and by the physiological activity of
the vegetation as affected by climate and
water availability. We have been able to
model these seasonal changes in the
physiological status of the plants and
their influence on surface fluxes. This was
an important milestone in testing our
model.

Neil Hoffman: The Role of 54CP in
Intrachloroplast Protein Sorting

One of the major unresolved problems
of chloroplast biogenesis is the
mechanism by which proteins are
translocated across or integrated into
chloroplast membranes. Progress has
been hindered by the fact that most of the
components of the protein-transport
machinery remain to be identified.
Previously our lab had cloned a gene
encoding a chloroplast protein that
exhibited structural homology to SRP54, a

Olle Bjorkman: Photophosphory-
lation, Energy Dissipation, and
Photoprotection under Prolonged
Salinity and Drought Stress

Last year I reported on the results of
our laboratory studies on
photophosphorylation, adenylate energy
charge, and energy dissipation under
conditions that severely restrict
photosynthetic CO2 fixation. These
studies raised the possibility that under
natural stresses such as drought, salinity,
and unfavorable temperatures, leaves
may be able to make use of some of the
absorbed light energy by continuing to
produce ATP even when they are
incapable of fixing CO2. In addition, the
continuation of electron flow under
severe stress would maintain a high
proton gradient across the chloroplast
membrane; this may allow the excess light
energy to be harmlessly dissipated and
thus protect the system from
photodamage.

PLANT BIOLOGY

67

During the past year some of these
predictions were tested under long-term
stress conditions on cotton plants grown
under natural sunlight. Much of this
work was conducted during my stay at
the Consiglio Nationale delle Ricerche,
Porano, Italy, in collaboration with Enrico
Brugnoli, a former fellow at this
department. Exposure of cotton to
long-term salinity stress under natural
sunlight resulted in a strong build-up of
ATP, a massive conversion of violaxanthin
to zeaxanthin, and a high rate of energy
dissipation (as determined by chlorophyll
fluorescence quenching analysis).
Maximal levels of ATP and energy
dissipation were reached when the leaf
salt concentration had risen to a level that
caused full stomatal closure and complete
cessation of net CO2 fixation. As expected,
the efficiency of photosystem 2 also was
quite low under these stress conditions.
Similar results were obtained in
experiments where the cotton plants were
subjected to water stress by gradually
restricting the water supply over several
weeks. It is noteworthy that even in the
most severe stress treatments, no
apparent photodamage could be detected.
Just a few minutes after darkening the
leaves, a very large fraction of leaf ATP
had been converted to AMP, accompanied
by an almost full relaxation of
fluorescence quenching. Moreover, the
efficiency of photosystem 2 rapidly rose
to approximately the same level as in
leaves of non-stressed control plants. Our
results thus indicate that
photophosphorylation can proceed at a
significant rate even under prolonged and
severe stress, and that energy dissipation
processes associated with protonation
and zeaxanthin formation may be
sufficient to protect against
photoinhibitory damage to photosystem 2.

Christopher Field: Modeling the
Global Carbon Cycle

The research in my laboratory

continues to focus on the global carbon
cycle, at a number of scales. At the
ecosystem scale, the group expanded its
studies on the responses of California
annual grasslands to elevated CO2, to
include emphases on closing the carbon
and water budgets, responses to limiting
nutrients other than nitrogen, and the role
of symbiotic nitrogen fixation. At the
global scale, the group developed a new
model of terrestrial plant production and
decomposition. This new model (CASA,
for Carnegie Ames Stanford Approach),
which was outlined in Year Book 92 (pp.
57-61), combines satellite and surface
data with physiological and ecological
principles to produce a picture of
biosphere activity that can be used to test
hypotheses or detect change during the
era of satellite observations.

Winslow Briggs: Phototropic Mutants
and Protein Phosphorylation

Postdoctoral associate Emmanuel
Liscum has obtained several new
phototropic null mutants (incapable of
phototropism, i.e., reorienting in response
to light) by screening populations of
Arabidopsis thaliana that had been
mutagenized with fast neutron
bombardment or Ti-plasmid insertion.
Two of these phototropic null mutants
completely lack a 120-kD plasma
membrane protein that normally becomes
phosphorylated when the plants or the
isolated membranes are exposed to blue
light. We have previously presented both
physiological and genetic evidence that
the phosphorylation of this protein plays
a role in the signal transduction chain for
phototropism. The two mutants are
genetically close to JK224, a mutant
described by Kenneth Poff 's laboratory at
Michigan State University, which we have
found to be deficient in this same protein.
Since some of Liscum's new mutants may
be deletion mutants, they may prove very
helpful in isolating the gene for the
protein. Since unlike JK224, the mutants

68

CARNEGIE INSTITUTION

lack second positive phototropic
curvature, completely lack first positive
curvature (present but altered in JK224),
lack phototropism in light-grown
seedlings, lack phototropism in roots, and

have no response to green light (normal
in JK224) or UV-A light, we tentatively
conclude that this protein is involved in
all of these phototropic responses.

Bibliography

1189 Apt, K. E., D. Bhaya, and A. R.
Grossman, Characterization of the genes
encoding the light-harvesting proteins in
diatoms: the biogenesis of the fucoxan-
thin chlorophyll a/c protein complex, /.
Appl. Phycol. 6, 225-230, 1994.

1213 Apt, K. E., S. K. Clendennen, D. A.
Powers, and A. R. Grossman, The gene
family encoding the fucoxanthin
chlorophyll proteins from the brown alga
Macrocystis pyrifera, Mol. Gen. Genet., in
press.

1228 Artus, N. N., S. Naito, and C. R. Somer-
ville, A mutant of Arabidopsis thaliaria that
defines a new locus for glycine decar-
boxylation, Plant Cell Physiol, in press.

1241 Asard, H., N. Horemans, W. R. Briggs,
and R. J. Caubergs, Blue light perception
by endogenous redox components of the
plant plasma membrane, Photochem.
Photobiol., in press.

1210 Berkelman, T., P. Garret-Engele, and N.
E. Hoffman, The pad gene of Synechococ-
cus sp. Strain PCC 7942 encodes a Ca2+-
transporting ATPase, /. Bacteriol. 176,
4430-4436, 1994.

1224 Berry, J. A., P. J. Sellers, D. A. Randall, G.
J. Collatz, G. D. Colello, S. Denning, and
C. Grivet, SiB2, a model for simulation of
biological processes within a climate
model, in SEB Seminar Series — Scaling Up,
P. van Gardingen, ed., Cambridge Univer-
sity Press, Cambridge, in press.

1211 Bhalerao, R. P., J. L. Collier, P. Gus-
tafsson, and A. R. Grossman, The struc-
ture of phycobilisomes in mutants of
Synechococcus sp. Strain PCC 7942 devoid
of specific linker polypeptides, Photochem.
Photobiol, in press.

1094 Bilger, W., and O. Bjorkman, Relation-
ships among violaxanthin deepoxidation,
thylakoid membrane conformation, and
nonphotochemical chlorophyll fluores-
cence quenching in leaves of cotton (Gos-
sypium hirsutum L.), Planta 192, 238-246,
1994.

1110 Bjorkman, O., and B. Demmig-Adams,

Regulation of photosynthetic light energy
capture, conversion and dissipation in
leaves of higher plants, in Ecophysiology of
Photosynthesis, Vol. 100, E.-D. Schulze and
M. Caldwell, eds., Springer- Verlag, Ber-
lin, Heidelberg, New York, pp. 17-47,
1994.
1196 Briggs, W. R., New light on stem growth,
Nature 366, 110-111, 1993.

1243 Briggs, W. R., E. Liscum, P. W. Oeller, and
J. M. Palmer, Photomorphogenic systems,
in Light as an Energy Source and Information
Carrier in Plant Physiology, R. C. Jennings,
G. Zuchelli, F. Ghetti, and G. Columbetti,
eds., Plenum Publishing, New York, in
press.

1227 Browse, J., and C. R. Somerville,
Glycerolipids, in Arabidopsis, E. Meyer-
owitz and C. R. Somerville, eds., Cold
Spring Harbor Press, Cold Spring Harbor,
New York, in press.

1221 Casey, E. S., and A. R. Grossman, In vivo
and in vitro characterization of the light-
regulated cpcB2A2 promoter of Fremyella
diplosiphon, J. Bacteriol. 176, 6362-6374,
1994.

1204 Cardon, Z. G., J. A. Berry, and I. E. Wood-
row, Dependence of the extent and direc-
tion of average stomatal response in Zea
mays L. and Phaseolus vulgaris L. on the
frequency of fluctuations in environmen-
tal stimuli, Plant Physiol. 105, 1007-1013,
1994.

1244 Ciais, P., P. P. Tans, J. W. C. White, M.
Trolier, R. J. Francey, J. A. Berry, D. R.
Randall, P. J. Sellers, J. G. Collatz, and D.
S. Schimel, Partitioning of ocean and land
uptake of CO2 as inferred by 513C meas-
urements from the NOAA/CMDL global
air sampling network, /. Geophys. Res., in
press.

1201 Collier, J. L., S. Herbert, D. C. Fork, and
A. R. Grossman, Changes in the cyanobac-
terial photosynthetic apparatus in
response to macronutrient deprivation,
Photosyn. Res., in press.

1177 Collier, J. L., and A. R. Grossman, A small

PLANT BIOLOGY

69

peptide elicits the degradation of
phycobilisomes during nutrient-limited
growth of cyanobacteria, EMBO J. 13,
1039-1047, 1994.

1202 Davies, J. P., and A. R. Grossman, Se-
quences controlling transcription of the
Chlami/domonas reinhardtii p2-tubulin gene
after deflagellation and during the cell
cycle, Mo/. Cell. Biol. 14, 5165-5174, 1994.

1176 Davies, J. P., F. Yildiz, and A. R.
Grossman, Mutants of Chlami/domonas
with aberrant responses to sulfur depriva-
tion, Plant Cell 6, 53-63, 1994.

1173 Dolganov, N., and A. R. Grossman, In-
sertional inactivation of genes to isolate
mutants of Synechococcus sp. Strain PCC
7542: isolation of filamentous strains, /.
Bacteriol. 175, 7644-7651, 1993.

1226 Dolganov, N. A. M., D. Bhaya, and A. R.
Grossman, Cyanobacterial protein with
similarity to the chlorophyll rt/ib-binding
proteins of higher plants: evolution and
regulation, Proc. Natl. Acad. Sci. USA, in
press.

1230 Falcone, D., S. Gibson, B. Lemieux, and
C. R. Somerville, Identification of a gene
that complements an Arabidopsis mutant
deficient in chloroplast co-6 desaturase ac-
tivity, Plant Physiol, in press.

1240 Field, C. B., Carbon cycle: Arctic chill for
C02 uptake, Nature 371, 472-473, 1994.

1151 Field, C. B., J. Gamon, and J. Penuelas,
Remote sensing of terrestrial photosyn-
thesis, in Ecophysiology of Photosynthesis, E.
-D. Schulze and M. M. Caldwell, eds.,
Springer- Verlag, Berlin, pp. 511-527, 1994.

1203 Field, C. B., J. T. Randerson, and C.
Malmstrom, Global net primary produc-
tion: combining ecology and remote sens-
ing, Remote Sensing of the Environment, in
press.

1217 Field, C. B., J. T. Randerson, C. M. Malm-
strom, and C. S. Potter, Ecological controls
on net primary production: lessons from
global models, in Scaling Up, P. van Gar-
dingen, G. Foody, and P. Curran, eds.,
Cambridge University Press, Cambridge,
in press.

1185 Fredeen, A. L., and C. B. Field, Con-
straints on the distribution of Piper
species, in Tropical Forest Plant Ecophysiol-
ogy, A. P. Smith, K. Winter, and S. Mulkey,
eds., Chapman and Hall, New York, in
press.

1181 Gamon, J. A., C. B. Field, G. Joel, M. L.
Golden, K. L. Griffin, A. E. Hartley, J.
Penuelas, and R. Valentini, Relationships
between NDVI, canopy structure, and
photosynthesis in three California vegeta-
tion types, Ecological Applications, in press.

1214 Gibson, S., V. Arondel, K. Iba, and C. R.
Somerville, Temperature regulated ex-
pression of a gene encoding a chloroplast
omega-3 desaturase from Arabidopsis
thaliana, Plant Physiol, in press.

1206 Gibson, S., D. L. Falcone, J. Browse, and
C. R. Somerville, Use of transgenic plants
and mutants to study the regulation and
function of lipid composition, Plant Cell
Environ. 17, 627-637, 1994.

1235 Giese, H., S. Hippe-Sanwald, S. Somer-
ville, and J. Weller, Erysiphe graminis, in
Mycota, Vol. VI, G. Carroll and P. Tudzyn-
ski, eds., Springer -Verlag, Berlin, in press.

1183 Gilmore, A. M., and O. Bjorkman,
Adenine nucleotides and the xanthophyll
cycle in leaves. I. Effects of CO2- and
temperature-limited photosynthesis on
adenylate energy charge and violaxanthin
de-epoxidation, Planta 192, 526-536, 1994.

1184 Gilmore, A. M., and O. Bjorkman,
Adenine nucleotides and the xanthophyll
cycle in leaves. II. Comparison of the ef-
fects of CO2- and temperature-limited
photosynthesis on photosystem II
fluorescence quenching, the adenylate
energy charge and violaxanthin de-
epoxidation in cotton, Planta 192, 537-544,
1994.

1141 Goulden, M. L., and C. B. Field, Three
methods for monitoring the gas-exchange
of individual tree canopies: ventilated-
chamber, sap-flow and Penman-Monteith
measurements on evergreen oaks, Func-
tional Ecology 8, 125-135, 1994.

1162 Grossman, A., M. Schaefer, G. Chiang,
and J. Collier, The responses of cyanobac-
teria to environmental conditions: light
and nutrients, in The Molecular Biology of
Cyanobacteria, D. Bryant, ed., in press.

1193 Grossman, A. R., D. Bhaya, and J. L. Col-
lier, Specific and general responses of
cyanobacteria to macronutrient depriva-
tion, in Molecular Biology of Phosphate in
Microorganisms, pp. 112-118, 1994.

1208 Hasunuma, K., T. Hamada, and W. R.
Briggs, Molecular analysis of phyto-
chrome-mediated signal transmission in
etiolated pea seedlings, /. Photochem.
Photobiol. B: Biol. 23, 245-251, 1994.

1191 Hoffman, N. E., and A. E. Franklin,
Evidence for a stromal GTP requirement
for the integration of a chlorophyll a/b
binding polypeptide into thylakoid
membranes, Plant Physiol. 105, 295-304,
1994.

1166 Huang, L., T. Berkelman, A. E. Franklin,
and N. E. Hoffman, Characterization of a
gene encoding a Ca2+-ATPase-like protein
in the plastid envelope, Proc. Natl. Acad.

70

CARNEGIE INSTITUTION

Sci. USA 90, 10066-10070, 1993.

1238 Jackson, R. B., O. E. Sala, C. B. Field, and
H. A. Mooney, CO2 alters water use, carb-
on gain, and yield in a natural grassland,
Oecologia, in press.

1215 Kehoe, D., and A. R. Grossman, Comple-
mentary chromatic adaptation: photoper-
ception to gene regulation, Seminars in Cell
Biology 5, 303-313, 1994.

1195 Liscum, E., and R. P. Hangarter, Muta-
tional analysis of blue-light sensing in
Arabidopsis, Plant Cell Environ. 17, 639-648,
1994.

1182 Luo, Y, H. A. Mooney, and C. B. Field,
Prediction of photosynthesis and root/
shoot ratio responses to elevated CO2
based on altered carbon and nitrogen
relationships, Plant Cell Environ., in press.

1219 McConn, M., S. Hugly, J. Browse, and C.
R. Somerville, A mutation at \hefad8 locus
of Arabidopsis identifies a second chloro-
plast omega-3 desaturase, Plant Physiol,
in press.

1232 Nawrath, C, Y. Poirier, and C. R. Somer-
ville, Targeting of the polyhydroxy-
butyrate biosynthetic pathway to the
plastids of Arabidopsis tlialiana results in
high levels of polymer accumulation,
Proc. Natl. Acad. Sci. USA, in press.

1233 Newman, T, F. J. de Bruijn, P. Green, K.
Keegstra, H. Kende, L. Mcintosh, J. Ohl-
rogge, N. Raikhel, S. Somerville, M.
Thomashow, E. Retzel, and C. R. Somer-
ville, Genes galore: a summary of the
methods for accessing the results from
large-scale partial sequencing of
anonymous Arabidopsis cDNA clones,
Plant Physiol., in press.

1164 Penuelas, J., J. A. Gamon, A. L. Fredeen,
J. Merino, and C. B. Field, Indices as-
sociated with diurnal and seasonal chan-
ges in the spectral reflectance of nitrogen-
and water-limited sunflower leaves,
Remote Sens. Environ. 47, 135-146, 1994.

1231 Poirier, Y, L. A. Schechtman, M. M. Sat-
kowski, I. Noda, and C. R. Somerville,
Synthesis of high molecular weight

poly([R] — 3-hydroxybutyrate) in trans-
genic Arabidopsis thaliana, Int. J. Biol. Mac-
romol., in press.

1170 Potter, C. S., J. T Randerson, C. B. Field,
P. A. Matson, P. M. Vitousek, H. A.
Mooney, and S. A. Klooster, Terrestrial
ecosystem production: a process model
based on global satellite and surface data,
Global Biogeochemical Cycles 7, 811-841,
1993.

1242 Quail, P. H., W. R. Briggs, J. Chory, R. P.
Hangarter, N. P. Harberd, R. E. Kendrick,
M. Koornneef, B. Parks, R. A. Sharrock, E.

Schafer, W. F. Thompson, and G. C. White-
lam, Spotlight on phytochrome nomen-
clature, Plant Cell 6(4), 468-471, 1994.

1192 Ribas-Carbo, M., J. A. Berry, and J. N.
Siedow, The reaction of the plant
mitochondrial cyanide-resistant alterna-
tive oxidase with oxygen, Biochim.
Biophys. Acta, in press.

1212 Robinson, S. A., M. Ribas-Carbo, D.
Yakir, L. Giles, and J. A. Berry, Beyond
SHAM and cyanide: studies of the alterna-
tive oxidase in plant respiration using
oxygen isotope discrimination, Aust. J.
Plant. Physiol., in press.

1172 Samson, G., S. K. Herbert, D. C. Fork, and
D. E. Laudenbach, Acclimation of the
photosynthetic apparatus to growth ir-
radiance in a mutant strain of Synechococ-
cus lacking iron superoxide dismutase,
Plant Physiol. 105, 287-294, 1994.

1167 Schaefer, M. R., G. G. Chiang, J. G.
Cobley, and A. R. Grossman, Plasmids
from two morphologically distinct
cyanobacterial strains share a novel
replication origin, /. Bacteriol. 175, 5701-
5705, 1993.

1229 Schneider, J. C, E. Nielsen, and C. R.
Somerville, A chilling-sensitive mutant of
Arabidopsis is deficient in chloroplast
protein accumulation at low temperature,
Plant Cell Environ., in press.

1246 Sellers, P. J., B. Meeson, F. G. Hall, G.
Asrar, R. E. Murphy, R. Schiffer, F Brether-
ton, F. Dickenson, R. G. Ellingson, C. B.
Field, F. Huemmrich, C. O. Justice, J.
Melack, N. Roulet, D. S. Schmil, and P. Try,
Remote sensing of the land surface for
studies of global change: models — algo-
rithms— experiments, Remote Sensing of
the Environment, in press.

1200 Short, T. W., and W. R. Briggs, The
transduction of blue light signals in
higher plants, Annu. Rev. Plant Physiol.
Plant Mol. Biol. 45, 143-171, 1994.

1104 Short, T W., M. Porst, J. Palmer, E.
Fernbach, and W. R. Briggs, Blue light
induces phosphorylation at seryl residues
on a pea {Pisiim sativum L.) plasma
membrane protein, Plant Physiol. 104,
1317-1324, 1994.

1175 Smith, H., G. Samson, and D. C. Fork,
Photosynthetic acclimation to shade:
probing the role of phytochromes using
photomorphogenic mutants of tomato,
Plant Cell Environ. 16, 929-937, 1993.

1161 Tian, G., J. A. Berry, and J. P. Klinman,
Oxygen- 18 kinetic isotope effects in the
dopamine-monooxygenase reaction: evi-
dence for a new chemical mechanism in
non-heme metallomonooxygenases, Bio-

PLANT BIOLOGY

71

chem. 33, 226-234, 1994.

1188 Valentini, R., J. A. Gamon, and C. B.
Field, Ecosystem gas exchange in a
California serpentine grassland: seasonal
patterns and implications for scaling,
Ecology, in press.

1156 Warpeha, K. M. R, and W. R. Briggs, Blue
light-induced phosphorylation of a plas-
ma membrane protein in pea: a step in the
signal transduction chain for photo-
tropism, Aust. J. Plant Physiol. 20, 393-403,
1994.

1245 Weaver, L. M., L. Lebrun, A. E. Franklin,
L. Huang, N. E. Hoffman, E. S. Wurtele,
and B. Nikolau, Molecular cloning of the

biotinylated subunit of c-methylcrotonyl-
CoA carboxylase of Arabidopsis thaliana,
Plant Physiol., in press.

1220 White, M. J., L. S. Kaufman, B. A. Hor-
witz, W. R. Briggs, and W. P. Thompson,
Individual members of the Cab gene fami-
ly differ widely in fluence response, Plant
Physiol., in press.

1171 Yildiz, F. H., J. P. Davies, and A. R.
Grossman, Characterization of sulfate
transport in Chlamydomonas reinhardtii
during sulfur-limited and sulfur-suffi-
cient growth, Plant Physiol. 104, 981-987,
1994.

Personnel

Research Staff

Joseph A. Berry1

Olle E. Bjorkman

Winslow R. Briggs, Director Emeritus

Christopher B. Field

David C. Fork

Arthur R. Grossman

Neil E. Hoffman

Christopher R. Somerville, Director2

Shauna C. Somerville2

Visiting Investigators

Ruth Alscher, Virginia Polytechnic Institute

and State University, NSF Fellow2
Devaki Bhaya, Jawaharlal Nehru University,

New Delhi, India
Pierre Broun, Monsanto Fellow3
Ewald Fernbach, Alexander von Humboldt

Stiftung Fellowship4
Ian Graham, University of Glasgow,

Scotland, British SERC Fellow2
Bernard Kloareg, Centre National de la

Recherche Scientifique, Lauderueau,

France5
Dov Koller, The Hebrew University,

Jerusalem6
Steven Lindley, Stanford University, Mellon

Fellow13
Harry Smith, University of Leicester, UK7
Assaf Sukenik, Israel Oceanographies &

Limnological Research, Haifa8

Postdoctoral Fellows and Associates
Luc Adam, NSF Research Associate2

Kirk E. Apt, NSF Fellow

Thomas R. Berkelman, NIH Research

Associate
Robin Buell, USDA Fellow2
Gregory D. Colello, NASA Research

Associate
G. James Collatz, NASA Research Associate9
Steven Daniel, Stanford/Carnegie Training

Fellow10
John P. Davies, USDA Research Associate
Deane Falcone, NSF Research Associate2
Arthur F. Fredeen, Mellon Fellow
Wei Fu, NASA Research Associate11
Adam M. Gilmore, Mellon Fellow12
David M. Kehoe, NSF Fellow
Xingxiang Li, NIH Research Associate
Emmanuel Liscum, NSF Research Associate
Christiane Nawrath, NSF Research

Associate2
Michelle Nikoloff, DOE Research Associate2
Krishna Niyogi, Stanford /Carnegie Training

Fellow14
Paul Oeller, NSF Research Associate
Joseph Ogas, NSF Fellow2
Julie M. Palmer, NSF Research Associate15
Marsha Pilgrim, Stanford /Carnegie

Training Fellow16
Yves Poirier, DOE Research Associate2
Wayne Stochaj, Stanford /Carnegie Training

Fellow17
Susan S. Thayer, NSF Research Associate
Yvonne Thorstenson, NIH Research

Associate18
Simon Turner, EMBO Fellow2
Jennifer Weller, NSF Research Associate19
Fitnat H. Yildiz, McClintock Fellow
James Zhang, DOE Research Associate2

72

CARNEGIE INSTITUTION

Predoctoral Fellows and Associates

Zoe G. Card on, Stanford University20
Elena M. Casey, Stanford University
Jackie L. Collier, Stanford University20
M. Elise Dement, Stanford University
Amie E. Franklin, Stanford University
Claire Granger, Stanford University2*
N. Michele Holbrook, Stanford University
Geeske Joel, University of Bayreuth
Catharina Lindley, Stanford University2
Chris Lund, Stanford University22
Carolyn Malmstrom, Stanford University
Margaret Olney, Stanford University
Patti Poindexter, Stanford University
John Quisel, Stanford University23
Steven Reiser, Michigan State University2
Seung Rhee, Stanford University, NSF
Fellow2

Support Staff

Ann Blanche Adams, Technician24
Cesar R. Bautista, Horticulturist
Mike Blaylock, Laboratory Assistant25

Nadejda A. Dolganov, Research Associate

Jane S. Edwards, Administrative Assistant

Celeste Falcone, Photographer26

Glenn A. Ford, Laboratory Manager

Cyril D. Grivet, Senior Laboratory Technician

Barbara A. March, Bookkeeper

Sylvia Martinez-Strauman, Research

Assistant27
Ann D. McKillop, Technician
Barbara E. Mortimer, Technician
Frank Nicholson, Facilities Manager
Pedro F. Pulido, Maintenance Technician
Jim Randerson, Technician
Larry D. Reid, Maintenance Technician
Connie K. Shih, Senior Laboratory Technician
David Smernoff, Research Assistant28
Mary A. Smith, Business Manager
Paige Thomas, Laboratory Assistant29
Julie M. Tritschler des Rosier, Technician
Thang Truong, Laboratory Assistant30
Rudolph Warren, Maintenance Technician
Aida E. Wells, Secretary
Brian M. Welsh, Mechanical Engineer
Howard Whitted, Support Engineer
Sunia Yang, Electrical Engineer

Acting Director to December

31, 1993
2From January 1, 1994
3From March 1, 1994
4To May 18, 1994
5To August 1, 1993
6To September 30, 1993
7From March 3 to April 30, 1994
8From August 1, 1993
9To September 30, 1993
10To April 30, 1994
nFrom March 31, 1994
12To September 30, 1993
13From May 1, 1994
14From September 7, 1993
15To August 15, 1993

16From August 30, 1993

17From March 25, 1994

18To May 31, 1994

19From January 1 to April 15, 1994

20To January 31, 1994

21From September 1, 1993

^From September 30, 1993

23From June 20, 1994

24From April 1, 1994

25From May 18, 1994

26From March 1, 1994

27From May 13, 1994

28From May 16, 1994

29From March 8, 1994

30From February 17, 1994

Geophysical Laboratory

KV^r

Skaergaard Intrusion, Greenland

° d> c

T3 O .^ -£
>■ .1—0)

The Director's Introduction

The two principal essays offered here illustrate important areas of
research in the earth and planetary sciences, ones that we
believe are leading to real understanding about the compositions
and structures of planetary interiors. Recent advances in theory,
computer modeling, and laboratory experiment, coupled with new
observations of planetary phenomena such as the recent meteorite
impacts on Jupiter, make this an exciting time for those of us who want
to know more about the evolution of the Earth and other planets. Tom
Duffy tells how laboratory experiments using the technique of Brillouin
scattering to determine sound velocities in solid hydrogen at high
pressure can provide constraints on the interpretation of the recently
reported global seismic oscillations of Jupiter. From this and other
information, scientists here and elsewhere are beginning to construct
reasonable models for Jupiter's interior structure. Then, Yingwei Fei
describes results obtained with a new diamond cell equipped with a
small, but well-designed heater that allows him to perform synchrotron
x-ray diffraction experiments while samples are raised to temperatures
and pressures as high as 1100 K and 125 GPa.* Such cells have been
described previously by others, but none have been used to produce
such a quantity of x-ray diffraction data over so wide a range of
temperature and pressure. In applying this cell to experiments on FeS
and FeO, Fei probably has generated more new information on the
phase relations in these systems in a few months than has been

*One gigapascal (GPa) is ten kilobars, or 10,000 times atmospheric pressure at sea
level.

75

76 CARNEGIE INSTITUTION

produced by all other investigators in all of previous history. Both FeS
and FeO have been proposed as possible components in Earth's core or
in the D" layer that resides between the core and the lower mantle, and
Fei's new information is essential for making further progress in
understanding these regions of the Earth. The subjects of both essays
are part of a growing interest in how the solar system formed and
evolved over billions of years as well as how Earth itself nucleated,
grew, and became what it is today.

Because research at the Geophysical Laboratory is very much
oriented around measurement of chemical and physical properties of
terrestrial and meteoritic samples, it is interesting to compare our
current activities with those that took place in former times in the Lab.
Recently, some of our staff members have been talking about a paper
published in 1923 by two staff members, E. D. Williamson and L. H.
Adams, "Density distribution in the Earth" (Journal of the Washington
Academy of Sciences 13, 413-428, 1923). This was a seminal paper,
probably the Lab's most important contribution to geophysics and
overall one of the key geophysics papers of the first half of the 20th
century. In his classic paper "Elasticity and constitution of Earth's
interior," Francis Birch wrote that Williamson and Adams were the first
to notice that seismic velocities give information about the change of
density with pressure. Their paper is still quoted today and, with a
companion paper in the same year (Adams and Williamson, "The
compressibility of minerals and rocks at high pressures," Journal of the
Franklin Institute 195, 475-529, 1923), the work represents remarkable
insight to problems still being discussed in 1994. Erskine D. "Sandy"
Williamson was a Scot who came to Washington as a staff member in
1914. He was a physical chemist and spent a year or so during World
War I working with Pittsburgh Plate Glass Company in the effort to
manufacture improved optical glass for the war effort. After returning
to the Lab, he and Adams published a series of papers that are exactly
what we would today call mineral physics. Unfortunately, Williamson
died at age 37 in 1923, the year the above papers were published. He
was married to Alice Boorman Williamson, a stenographer/editor at
the Lab, who remained an employee until 1947. Leason Adams, of
course, became director of the Lab in 1937.

It is exciting that today many of the questions asked by Williamson
and Adams are being answered. We can now perform experiments
under conditions approximating those of the mantle and core and make
in situ measurements that would have been impossible just a few years
ago. Experimental work by Tom Duffy and theoretical modeling by Iris
Inbar and Ronald Cohen provide new information on the behavior of
MgO at ultrahigh pressures. While pure MgO probably does not exist
in the lower mantle, its study is a first step toward experiments on
similar phases containing iron and other cations as well as magnesium.

GEOPHYSICAL LABORATORY 77

Michael Walter's studies of the partitioning of elements between
silicate and iron at high pressures and temperatures are another
example of experiments that benefit from new tools and increased
awareness of the questions that need asking. Kathleen Kingma and
Ronald Cohen have shown that the high-pressure Si02 mineral
stishovite will transform to a denser phase with the CaCl2 structure at
about 50 GPa and room temperature. This structure could be significant
in the lower mantle because it is predicted to exhibit substantially
different elastic (i.e., seismic) properties from those of stishovite at high
pressures.

Another area of increased current interest is in the role of volatiles
such as H20 in geological processes, not only at ultrahigh pressures but
throughout the Earth and throughout its history. David Bell's thesis
work at Caltech emphasized the detection and characterization of
hydrogen in nominally anhydrous minerals from the upper mantle.
Now, he and Tom Hoering are examining the ratios of the isotopes
deuterium H2 and hydrogen H1 to determine whether specific mantle
source regions exhibit characteristic isotopic signatures. A long-term
goal of this and other investigations is to determine whether volatiles
we see on Earth today were introduced in the original accretion process
or added via comets or meteorites later in Earth's history.

An exciting aspect of research at the Geophysical Laboratory is
that, even though our staff is relatively small compared to those of
many other institutions in the world, we are engaged in a wide variety
of research projects. One of these projects was initiated by John Frantz
and Deborah Kelley during one of John's visits to Woods Hole
Oceanographic Institution. Kelley collected samples of gabbro during a
cruise to the South Indian Ridge and brought them to the Lab for
analysis of fluid inclusions from the rocks, which contain a very large
amount of methane. Why is there so much methane in these rocks,
where does it come from, and what does its occurrence tell us about the
circulation of hydrocarbons in the Earth's crust and mantle? With Tom
Hoering's involvement, we have the capability of analyzing the fluid
inclusions; we hope that continued collaboration with Woods Hole will
provide answers to these questions.

In a time of questioning about the future for scientific research in
the United States, the Geophysical Laboratory is developing new ideas
and exploring new fields, meanwhile retaining its roots, centered on the
application of fundamental physical and chemical knowledge and
practices to the study of the Earth and the other planets. It is truly an
exciting time to be involved in these varied research activities.

— Charles T. Prewitt

78

CARNEGIE INSTITUTION

Properties of Hydrogen at High Pressure:
Implications for Jovian Seismology

by Thomas S. Duffy

The impacts of fragments of comet Shoemaker-Levy 9 into Jupiter
in July 1994 were among the most spectacular events in the history
of planetary science (Fig. 1). With almost every
astronomical observatory in the world (and in space)
viewing the collisions, a vast amount of new information
about Jupiter was obtained. The Jovian planets contain
99% of the planetary mass of our solar system.
Understanding the internal workings of these bodies is
critical for understanding the solar system as a whole.

Our current view of the interior structure of Jupiter is
limited and largely theoretical (Fig. 2). Existing models
are constructed to satisfy gross observational data for the
mass, rotation rate, radius, and gravitational harmonics of
the planet. Jupiter is composed dominantly of fluid
hydrogen, along with about ten percent helium and small
amounts of denser materials that can be grouped into ice
(e.g., H2O, NH3) and rock (e.g., Fe, Si02) components. The
pressure-density relation, or equation of state, of hydrogen is a source
of great uncertainty in interior models. At a depth of perhaps 20% of
the planet's radius, hydrogen is believed to undergo a transformation
from an insulating molecular state to a metallic fluid. The actual

Thomas Duffy

Fig. 1. Hubble Space Telescope images of Jupiter taken on July 17, 1994, showing
impact sites of fragments of comet Shoemaker-Levy 9. The images are taken in
violet, or visible (left), and in ultraviolet (right) light. Three impact sites are seen
across the bottom; a Jovian moon appears as a dark spot in the northern hemisphere.

losphere -^

\ .

-

~ — ,.

, 'J^""

V;

^ Molecular H2

+ He

^\^ s

/ / /

Metallic H +

He

V

\

' / /

rock

+ ice core -— .

5000 GPa
25,000 K

200 GPa
10,000 K

1 bar
165 K

Fig. 2. Interior structure of Jupiter as generally modeled. Approximate pressures
and temperatures are shown at bottom. The 1-bar pressure level is a convenient
reference point for interior models. The equatorial radius of Jupiter at this level is
71 ,492 km, about 1 1 .2 times the radius of the Earth.

location of this phase transition is unknown, and in current Jovian
models ranges from pressures of 100 to 500 GPa. The central pressure
and temperature of Jupiter are estimated to be about 5000 GPa and
25,000 K; the former is fifty million times greater than the pressure at
the Earth's surface.

Knowledge of the internal structure of the Earth is obtained from
the seismic waves generated by terrestrial earthquakes, which
propagate through the interior of the planet. Similarly, the strongest
constraints on the interior structure of the Sun are derived from
helioseismology — the study of solar acoustic oscillations. The
Shoemaker-Levy impacts might provide new information on the
interior of Jupiter if the arrival of seismic waves generated by the
impacts can be detected. Such waves could be observed by measuring
small temperature differences arising from the pressure variations
associated with the waves, or as Doppler shifts of spectral lines arising
from wave motion.

But whether or not such phenomena are actually observed from
Shoemaker-Levy, the field of Jovian seismology is expanding rapidly. A
number of theoretical studies of global seismic oscillations of the Jovian
planets have been performed, and the first observational searches have
been carried out. In 1991, a group of French astronomers reported the
successful observation of global free oscillations of Jupiter. The
observations are intriguing because of the unexpectedly large
amplitudes and profound implications for interior models, as discussed
below.

Laboratory Studies

Studies of global oscillations or impact-induced seismic waves are
by themselves insufficient to unravel the interior structure of planetary
interiors. As with terrestrial seismology, seismic observations must be
combined with laboratory data on sound (i.e., seismic) velocities and
equations of state of the appropriate materials under the extreme
pressure and temperature conditions existing within these bodies. To
address this need, Willem L. Vos, Chang-sheng Zha, Russell J. Hemley,

15

£ 10

_,--"'

■ " "J^-^ — -"""""•

"D

■g

„ - --J^_

"•

_2

o
to

„^^^

^^»

t

-" J^^^

J^""*

•

- - YR model

I

i

— HSG model

!

10

15

20

25

Pressure (GPa)

Fig. 3. Sound (i.e., seismic) velocity in H2 at room temperature as a function
of pressure. Solid symbols are experimentally measured data. Curves show
velocities calculated from intermolecular potentials: HSG, this study (solid line);
YR, calculated from earlier shock data (dashed line). The vertical line is the
melting boundary (at room temperature).

Ho-kwang Mao, and I began an effort to measure sound velocities in
compressed hydrogen and to understand their implications for Jovian
seismology.

We first developed new methods for measuring sound velocities in
planetary materials at elevated pressure in the diamond-anvil cell. The
technique involves measuring acoustic velocities through Brillouin
spectroscopy — the scattering of light from thermally generated sound
waves. At the same time, crystallographic orientation is determined by
synchrotron x-ray diffraction. In this way, a complete description of the
seismic properties of dense hydrogen can be obtained.

When compressed at room temperature, molecular hydrogen
remains a fluid until 5.4 GPa, at which point it crystallizes into a solid
with a hexagonal close-packed crystal structure (see figure legend, p.
86). For fluid H2, sound velocities are directly obtained from measured
Brillouin frequency shifts. For crystalline H2, compressional- and
shear-wave velocities were measured for 15-20 separate
crystallographic orientations at each of six pressures between 6 and 24
GPa. From these measurements, we obtained sound velocity as a
function of pressure (Fig. 3).

In addition to seismic velocities, constraints on the behavior of
high-density hydrogen are obtained from pressure-volume, i.e.,
equation of state (EOS), data. Our synchrotron x-ray diffraction
measurements on H2 tightly constrain the equation of state between 5.4
and 42 GPa at room temperature (Fig. 4). The EOS of hydrogen has also
been studied at high pressures by shock compression, where samples
are abruptly compressed by projectile impact. Shock-wave techniques
have the advantage that measurements are made directly on a
high-temperature fluid. On the other hand, static experiments are more

Density (g/cm3)

Fig. 4. Pressure-density data for H2. To
the right are experimental data from the
diamond cell (dots) along with curves
from the HSG and YR model calculations,
all at room temperature. Starting at far left
are HSG and YR model data at Jovian
temperatures (2500 K and 4500 K are
indicated). Data from shock experiments
(triangles) and model data at equivalent
high temperatures (lower branch of
curves) are shown. Good agreement
between the experimental data and the
HSG model is generally evident. The
complementary nature of the diamond-
anvil and the shock data is seen.

precise, cover a wider range of density, and allow direct measurements
of sound velocities. Through combination of the two types of data, an
understanding of the pressure-volume behavior of hydrogen over a
broad range of experimental conditions can be obtained.

Experimentally Based Models

Interactions between molecules are described using an empirical
pair-wise intermolecular-potential model. The intermolecular potential
is effective in the sense that orientational effects are averaged and
many -body terms are included implicitly. Many such models for
hydrogen have been constructed, primarily using low-pressure
experimental data. These models fail at high pressure because they do
not adequately reflect the attractive many-body forces that become
important under these conditions. Using shock-wave data, Marvin Ross
and colleagues at Lawrence Livermore National Laboratory developed
a model (the YR potential) for hydrogen that has subsequently been
widely used in modeling the interior of Jupiter. Comparisons of the
predictions of this model with equation of state and sound velocity
data (Figs. 3 and 4) reveal that the YR potential is in error at high
pressures. We have constructed a new form of this potential (called
HSG) that fits both static compression and sound velocity data (Figs. 3
and 4), and is also reasonably consistent with shock results. With our
HSG model, which fits a wide range of experimental data, it is now
possible to obtain better constraints on the properties of the molecular
layer of the Jovian planets.

For both models, equations of state and sound velocities were
calculated for pure H2 at Jovian conditions (an adiabat starting at T =
165 K at 1 bar) using fluid perturbation theory (Figs. 4 and 5). (Fluid
perturbation theory provides a statistical mechanical description of the
fluid from which thermodynamic properties can be obtained.) At low

82 CARNEGIE INSTITUTION

pressures, there is little difference between the two equations of state.
At higher pressures, the equations of state diverge such that at 25-300
GPa the HSG EOS is 6-11% denser than the YR EOS. Thus, our new
experimentally determined potential indicates that molecular hydrogen
is significantly denser under Jovian conditions than found in previous
models.

Comparisons to Observed Seismic Data

An important question is whether the acoustic properties of
hydrogen determined here are consistent with the observed global
oscillations of Jupiter. A basic parameter derived from the acoustic
observations is the equidistance v0 •* The equidistance can be thought of
as a fundamental frequency of oscillation — derived from and therefore
strongly dependent on values of and variations in seismic velocity in
the planet's interior. Although interpretation of currently available
spectra is difficult, the observed value of the equidistance of Jupiter is
estimated to be 136 ± 10 mHz for low-degree modes. In contrast, values
of v0 computed from existing Jovian models range from 156 to 160
mHz, a discrepancy of about 15%.

If the oscillation observations are correct, then substantial revision
of the models would seem required. And, since the planet's outer
region, composed mostly of molecular H2, contributes a high
percentage, about 40%, to the value of v0 for Jupiter, it is especially
important to consider how variations in equation of state, temperature,
and composition within that region would affect equidistance (i.e.,
seismic velocities) in the Jovian models.

Figure 5 shows seismic, or sound, velocities in H2 calculated using
the HSG and YR potentials. The HSG potential yields seismic velocities
that are up to 7% lower than the YR potential at high pressure. If the
molecular portion of older Jovian interior models is adjusted to reflect
the lower HSG velocities of Figure 5, the equidistance for the Jovian
interior is reduced by -1.6%. Although this is in the correct direction to
explain the seismic discrepancy, it accounts for only -10% of the
difference between observations and models. Thus, the improved EOS
for molecular H2 can only partially explain the apparently anomalous
seismic properties of Jupiter. Indeed, the magnitude of the change in
the H2 equation of state that would be required to fit the observed
seismic data lies well outside of experimental uncertainties in the data.

Other features of Jovian models that might need modification
include the interior temperatures, core size, composition, molecular-
metallic phase transition, interior stratification, and the metallic

*The equidistance is the inverse of twice the travel time of a ray from the planet's
center to the surface.

300

Pressure (GPa)

Fig. 5. Sound velocities in H2 (Jovian temperatures) calculated using the HSG and
YR potentials. The bold curve shows the sound velocities in Jupiter's molecular
region required to satisfy the current observed seismic data. Also shown are sound
velocities at the same Pand T conditions for He, H20, and rock. Does the presence
of these materials in the molecular region help explain the variance between the
calculated H2 and the Jovian observed sound velocities? Other evidence suggests
that this is only partly the case.

equation of state. The effect of changes in interior temperatures perhaps
due, for example, to a thermal boundary layer near the Jovian surface,
can be assessed using different starting temperatures in the
computation. Using initial temperatures of 65 K and 265 K will produce
temperatures in the deep interior that differ by 5000-6000 K, but the
sound velocity difference is less than 1% at these pressures. If the sound
velocity changes are restricted to the thermal boundary layer itself, the
change in the equidistance is not significant. Adjusting the metallic
phase transition level from 171 to 500 GPa affects the equidistance by
4%, higher transition pressures corresponding to higher equidistances.
If the phase transition occurs continuously over this range, however,
the equidistance is reduced from its value at 171 GPa by only 1-2%.

Experimental sound speeds in fluid H2-He mixtures at high
pressure can be used to infer compositional effects on sound velocities.
From currently available data, we have developed a simple model
which describes the variation of seismic velocity with composition.
Applying this model to Jupiter, we find that an approximate doubling
of the helium mass fraction in both the metallic and molecular regions
is required to reduce the sound velocities by the amount required to
satisfy the seismic data. This is far in excess of values from observations
of He in the Jovian atmosphere or from the expected abundance of He
in the primordial solar system. Similar conclusions hold when other
possible constituents (ices, rock) of the Jovian interior are considered.
Whether large increases in the non-hydrogen component can be
reconciled with gravity and mean density data needs to be examined in
future Jovian models. Additional laboratory studies of the seismic

84

CARNEGIE INSTITUTION

properties of mixtures of planetary fluids are also urgently needed for
further progress.

To resolve the discrepancy between seismic observations of Jupiter
and laboratory data, it may be necessary to consider new classes of
Jovian interior models. Alternatively, improvements in observational
data, perhaps arising out of the Shoemaker-Levy events, may yield
further insights into the interior properties of Jupiter. Nevertheless,
results obtained to date show that new observations in planetary
astronomy coupled with experimental advances in the study of
high-pressure hydrogen can significantly improve our understanding
of the internal structure of the outer planets and hence the solar system
as a whole.

Studying Core Materials at High Pressures
and Temperatures

by Yingwei Fei

The Earth's core comprises more than half the Earth's radius. Its
pressure ranges from 135 GPa at the core-mantle boundary to 364
GPa at the center of the Earth. The temperature distribution in the core,
however, has been a subject of considerable debate. Estimates based on
melting temperatures of possible core materials are
dependent on the composition of the core. The needed
compositional constraints are derived from
cosmochemical arguments and accurate measurement of
the high-pressure and high-temperature properties of
core materials. Thus, on the basis of its cosmochemical
abundance and its density, iron has long been considered
as the primary constituent of the Earth's core. However,
comparison between the equation of state of iron and
observed seismic data indicates that the core is about ten
percent less dense than pure iron at core pressures and
temperatures. This density deficit implies that a
substantial amount of light elements such as H, O, S, C,
Si, or Mg may be incorporated into the core. In the last
three decades, scientists have hypothesized as to the
identity of the light elements present in the core and how these light
elements were incorporated. Although many light elements have been
proposed, the high-pressure and high-temperature properties of iron
compounds with these proposed light elements, such as FeO and FeS,
have not been studied experimentally.

Yingwei Fei

TC1

Fig. 1. Experimental configuration
of a high-temperature diamond-anvil
cell. The sample is contained
between two single-crystal diamonds
(see expanded view) and is
compressed by force applied through
the lever arm. High temperature is
achieved by a small molybdenum-
wire resistance heater around the
diamonds and a large heater fitted
around the extruded portion of the
piston-cylinder. Temperature is
measured by thermocouples directly
adjoining the sample chamber (TC1
and TC2). The x-ray diffracted
spectra are collected with an intrinsic
germanium solid-state detector.

High-pressure and high-temperature experiments on iron
compounds are tricky because iron occurs in several different valence
states. Further, iron reacts with most of the conventional materials used
to contain samples in such experiments. Another problem is that most
of the high-pressure and high-temperature phases of iron compounds
are non-quenchable (i.e., they change phase upon return to room
conditions). Therefore, measurements of samples while they are at high
pressure and temperature are essential for the study of the
high-pressure and high-temperature behavior of core materials such as
FeO and FeS.

The diamond-anvil cell is the primary high-pressure tool for
studying the deep interior of the Earth. The pressure at the center of the
Earth can be generated between two gem-quality single-crystal
diamonds in the laboratory. Achieving high temperature at high
pressure is more challenging. Laser-heating and external /internal
resistance-heating techniques have been developed for simultaneous
high-pressure and high-temperature experiments, but few experiments
have involved simultaneous pressure, temperature, and x-ray
diffraction measurements. Figure 1 shows a newly designed, externally
heated high-temperature diamond-anvil cell. This instrument is capable
of achieving pressures over 125 GPa at temperatures up to 1100 K. It
has the advantage of providing uniform heating across the sample
chamber for long periods of time. It is ideal for in situ experimental
studies of the phase relations of materials at high pressure and high
temperature, and for determining the structure and physical properties
of each stable phase. The following examples of experiments on FeS
and FeO demonstrate use of the technique.

On the basis of cosmochemical and petrological arguments, it has
been proposed that sulfur may be the lighter alloying element in the
cores of the Earth and other terrestrial planets such as Mars.
Knowledge of the various forms, or polymorphs, of FeS that occur at

86

CARNEGIE INSTITUTION

high pressure and high temperature, and their physical properties, is of
particular importance in understanding the composition and
temperature of the core. The high-pressure polymorphism of FeS at
room temperature has been studied previously up to 60 GPa, but not
under the simultaneous high pressure and temperature conditions
relevant to the interiors of planets. Having recognized this need, we
conducted in situ synchrotron x-ray diffraction measurements of FeS at
simultaneous high pressure and high temperature using the
high-temperature diamond cell described above.

Our experimental data revealed five polymorphs of FeS, which are
closely related to a simple NiAs-type hexagonal structure. Figure 2
illustrates the structure of FeS V based on a close-packing hexagonal
lattice type. Figure 3 shows our experimentally determined phase
diagram of FeS. At 300 K, we confirmed two previously observed phase
transitions. Troilite (FeS I), a NiAs-type structure (a hexagonal close-
packed structure) with a (V3fl,2c) unit cell transforms to a MnP-type
structure (FeS II) at 3.4 GPa. A high-pressure phase (FeS III) forms at
pressures above 6.7 GPa. Upon heating at pressures below 4 GPa,
troilite (FeS I) transforms to a new hexagonal phase with a (2fl,c) unit
cell (FeS IV), and then to a simple NiAs-type structure with an (a,c) unit
cell (FeS V). Having analyzed all the spectra collected at different
temperatures, we then plotted the lattice constants a and c and the c/a
ratio as a function of temperature at 3 GPa (Fig. 4). The c/a ratios show
a clear discontinuity between FeS I and FeS IV. A slope change of the
c/a ratio as a function of temperature can be detected between FeS IV
and FeS V. Also, the lattice constant c decreases with increasing
temperature in the stability field of FeS IV and FeS V

Fig. 2. The structure of FeS V, a hexagonal close-packed
structure with an {a,c) unit cell.

Each unit cell of a crystalline structure consists of several
atoms, bonded and arranged according to a common and
repeating pattern. A crystal may consist of billions of unit cells
situated row-on-row along its lattice.

The NiAs-type structure is a hexagonal close-packed
structure. One can envision such a structure by placing a layer of
oranges at the floor of an hexagonal carton. Lemons are then fit
into voids between the oranges to form another hexagonal
close-packed layer. Alternating layers of oranges and lemons
would then fill the carton in a highly efficient packing
arrangement.

The oranges represent Fe atoms, the lemons S atoms in a
hexagonal close-packed FeS structure. The lattice constants a
and b(a= b) measure distance between the centers of Fe (or S)
atoms on a given layer. The lattice constant c measures distance
between the centers of two Fe (or two S) atoms across layers.

In the FeS IV {2a, c) structure, for example, Fe atoms are
slightly displaced such that a perfectly repeating unit cell occurs
by doubling the a distance.

F(

r

vy

■\_

V i

/

n

/^

n-

/

9

b

H

\/

\

\

At-

x

/

t

/

^

V^

1

V

N

A-,

?

FeS

900

10 15 20

Pressure (GPa)

Fig. 3. Experimentally determined
phase diagram of FeS. Symbols
show experimental measurements,
which serve to delineate the phase
boundaries. Solid squares, FeS I,
NiAs-type structure with a (V3a,2c)
unit cell; open circles, FeS II,
MnP-type structure; open squares,
FeS III; open triangles, FeS IV,
NiAs-type structure with a (2a,c) unit
cell; solid circles, FeS V, NiAs-type
structure with an (a,c) unit cell.

These five structural forms, or polymorphs, of FeS were identified
by x-ray diffraction. None of the high-pressure and high-temperature
phases of FeS are quenchable. The phase boundaries, which are
reversible, were mapped by in situ x-ray diffraction measurements. The
discovery of the FeS III-FeS IV phase boundary has important
implications for the temperature of the core if FeS is a major core
constituent. By linear extrapolation of the FeS III-FeS IV phase
boundary, it is expected that a triple point (FeS III-FeS IV-FeS liquid)
exists under Earth's core conditions, which may significantly affect the
temperature profile of the core.

The experimental results also have direct applications to the
interiors of small terrestrial planets such as Mars because the pressures
and temperatures in these bodies are more comparable to the
experimental conditions. Previous calculations suggest that the
pressure at the Martian core-mantle boundary may lie between 18 and
28 GPa, depending on the sulfur content of the core. However, these
calculations were based on a wrong polymorph of FeS. In light of our
discovery of the FeS IV phase and accurate density information on this
phase, the relationship among the Martian core-mantle boundary,
sulfur content, and density of the Martian core needs to be reexamined.

While we consider FeS to be a possible light member of the Earth's
core, FeO is another candidate. In order to demonstrate that oxygen (in
the form of FeO) is a potential alloying element in the core, it is
necessary to understand the high-pressure and high-temperature
behavior of FeO. At room temperature, FeO undergoes a structural
transition (from NaCl-type to a rhombohedral distortion) at 16 GPa. A
shock-wave study (high temperature) revealed another transition near
70 GPa. This high-pressure phase may be metallic, as suggested in
electrical resistivity measurements. The structure of this high-pressure

3.47

3.46

3.45

o< 3.44

cc 3.43

3.42

3.41

3.40

5.84

5.82

5.80

0< 5.78

O 5.76

5.74

5.72

5.70

1.72

1.70

•5 1.68

Fig. 4. How lattice constants a
and c and ratio cla change with
temperature at pressure 3 GPa in
FeS. The discontinuities signifying
phase transitions between FeS I,
FeS IV, and FeS V are evident.

1.66

1.64

• •%

••-•#

•H

♦ •

o°oi>

FeS I

(V3a, 2c)

O,

;oa

*b

9o

FeS IV
(2a,c)

CL

o

FeSV O
(a,c)

O

200

300

400

500

600

700

800

Temperature (K)

900

phase has been the subject of speculation because of lack of in situ x-ray
diffraction measurements at high pressure and high temperature.

Our new high-temperature diamond cell, combined with the
intense synchrotron x-ray diffraction, allows us to determine the
structure of non-quenchable high-pressure and high-temperature
phases. In situ x-ray diffraction measurements of FeO at pressures
above 70 GPa and temperatures between 300 K and 1100 K revealed
that the high-pressure phase of FeO has the NiAs-type structure with
lattice constants a = 2.574 A and c= 5.172 A, and a c/a ratio of 2.01 at 96
GPa and 800 K. Figure 5 shows our experimentally determined phase
diagram of FeO. The discovery of the high-pressure NiAs-type phase of
FeO has significant implications for the composition of the Earth's core.
The transition from the ionically bonded structure of the NaCl type to
the covalently and metallically bonded structure of the NiAs type in
FeO indicates a relative increase in metallicity at high pressure, which
is consistent with the high-pressure phase being metallic. The latter
structure at high pressure would enhance the solubility of oxygen (in
the form of FeO) in molten iron. This new discovery provides a
physicochemical basis for incorporating oxygen into the Earth's core.

Our new experimental results show that FeO and FeS have similar

FeO

3300

2800

2300

3

cS 1800

1300

800

300

y

Liquid

,''' I

,''

/

L

Jif

shock

wave

data

NaCI-type

I •

NiAs

type

-

/ A \

•
•

V$±

A *\

Rhombohedral a \

1 L-A L

20 40 60 80 100

Pressure (GPa)

120

140

Fig. 5. Experimentally
determined phase diagram of
FeO. Points are measurements
recently obtained at the
Geophysical Laboratory. Squares,
NaCI cubic phase; triangles,
rhombohedral distortion; circles,
NiAs-type structure. The density
discontinuity in the shock-wave
data shows phase boundary.

structures and chemical bonding at high pressure and high
temperature. It is thus possible that FeO and FeS form a solid solution
at high pressure and high temperature, which opens a possibility for
incorporating both oxygen and sulfur in the Earth's core.

We are still far from knowing the details of the composition of the
Earth's core. The experimental approach to this classic problem is to
obtain constraints necessary to eliminate possible core candidates. The
high-temperature diamond cell, combined with synchrotron x-ray
diffraction, provides a powerful tool for studying structure and
physical properties of core-related materials at simultaneous high
pressure and temperature. Our future work will focus on a systematic
determination of structure, phase relations, and density as functions of
pressure and temperature of core-related materials by x-ray diffraction.
In situ electrical resistivity and Mossbauer spectroscopic measurements
will be introduced to understand the electronic structure and electronic
transitions of core materials at simultaneous high pressure and high
temperature. These research results will provide strong constraints on
the composition of the Earth's core.

Short Reports

David Bell and Thomas Hoering:
HzO Contents and D/H Ratios of
Mantle Amphiboles

Present indications are that
interactions between mantle rock and

mobile hydrous phases play an important
role in the Earth's global hydrogen
(water) cycle, and strongly influence
internal geophysical and geochemical
processes. Deuterium /hydrogen ratios

90

CARNEGIE INSTITUTION

Thomas Hoering

are, in principle, useful in
characterizing reservoirs of
mantle hydrogen and as tracers
of volatile transfer processes in
Earth's interior. Mantle-derived
amphibole megacrysts
transported to the surface in
alkali basalts represent a
widespread source of mantle
water samples, yet measured H
contents and D/H ratios of such
samples have in the past
presented a confusing picture,
with suspected disturbance of primary
signals by near-surface processes. We
have departed from previous studies in
analyzing a large number (17) of
amphiboles from a localized region of a
composite volcanic center at Dish Hill,
California, in order to determine the
cause of this variation and explore the
possibility that the undisturbed mantle
D/H ratio can be deduced. Surprisingly
little variation in D/H ratio was
observed, with 5Dsmow = -46 ± 7%o (2s,
h=15) and H2O concentration of 0.93-1.15
wt %. These values probably represent
the original mantle D and H contents,
although we will explore the less likely
possibility that they have been
homogenized by crustal fluids during the
water-rich explosive maar phase of the
eruption. Two of the samples have
significantly lower H contents, 0.04 and
0.6 wt % H2O, respectively, the latter
sample having 5Dsmow = -9%o. H may
have been lost from these samples, with
accompanying isotopic disturbance,
during eruption. These results provide
tentative evidence that mantle
amphiboles can be used to fingerprint the
D/H ratios of their mantle source regions,
and thus help to characterize various
reservoirs of mantle water and the
processes that produced them.

Thomas S. Duffy: Magnesium Oxide
at Ultrahigh Pressure

MgO is an important refractory

ceramic and may comprise a significant
portion of the Earth's lower mantle. An
ultrahigh-pressure static compression
study was undertaken to resolve
long-standing questions regarding the
equation of state and phase stability of
this fundamental material.

In collaboration with Russell J.
Hemley and Ho-kwang Mao, experiments
on MgO were conducted using
synchrotron x-ray diffraction in a
diamond-anvil cell. It was found that
magnesium oxide remains in the NaCl
structure from ambient pressure to at
least 227 GPa. This is a remarkable range
of stability, but one that is nevertheless
consistent with the latest theoretical
predictions of Ronald Cohen and
colleagues. A surprising result of our
study was the large value of the static
shear strength of MgO at high pressures.
When this strength is taken into account,
it is possible for the first time to construct
an equation of state which
simultaneously satisfies the results of
static compression, shock wave, and
ultrasonic elasticity experiments on MgO.
Our results also require significant
changes in the degree and character of the
elastic anisotropy of MgO at high
pressure, an interesting finding which
warrants further investigation.

Reto Giere and Douglas Rumble:
History of Tourmaline Growth in
Metamorphic Schists from the
Central Alps

Large crystals of euhedral tourmaline
are unusually abundant in metapelitic
garnet-kyanite-staurolite schists from
Campolungo, Switzerland, an area that
underwent amphibolite facies
metamorphism during the Alpine
orogeny. The occurrence of such
quantities of tourmaline requires the
presence of boron in concentrations that
are not common for metapelites.

In our samples, tourmaline exhibits an
optically visible three-stage zoning (core,

GEOPHYSICAL LABORATORY

inner rim, outer rim). These zones are
separated by two discontinuities of
strikingly different appearance: the first
outlines a euhedral core and marks the
beginning of a new growth stage,
whereas the second (between inner and
outer rim) is sutured and clearly
represents a corrosion event before the
final growth. Electron microprobe
analyses reveal a complex pattern of
continuous and discontinuous chemical
zoning; the most pronounced chemical
gradient is found at the corroded surface,
where the outer rim is markedly richer in
Mg and Na, but poorer in Al, Fe, and Ca,
suggesting that the outer rim grew under
significantly different metamorphic
conditions.

In order to characterize the conditions
of tourmaline growth, we are currently
determining the oxygen isotopic
composition of each zone. Our first
results, obtained by laser-fluorination of
clean separates, indicate that these
tourmalines exhibit an oxygen isotopic
zoning, in addition to the chemical
zonation. In our investigation, we also
attempt to analyze the zones as to their
boron isotopic composition, which should
point to a possible source of the boron
required for tourmaline growth.

Our study suggests that zoned
tourmaline is a very promising
petrogenetic indicator. We hope that our
isotopic and microchemical results will
help in establishing a correlation between
tourmaline growth, circulation of fluids,
and metamorphic and structural
evolution of the metapelitic rocks.

Glenn A. Goodfriend, Michaele
Kashgarian, and M. G. Harasewych:
Aspartic Acid Racemization and the
Life History of Deep- Water Slit Shells

Racemization (or epimerization) of
amino acids has traditionally been used
for dating samples beyond the range of
radiocarbon dating (about 45,000 years).
Recent studies have shown that one

Electron microprobe views showing zonations of Fe, Al, and
Mg in a sample of tourmaline from Campolungo, Switzerland.
In each view, the upper part shows the inner rim, the lower part
the outer rim, of tourmaline. The lower left area in each is the
muscovite matrix in which the tourmaline is embedded. The
view at lower right is a backscattered electron picture of the
same area. The sutured boundary between the inner and outer
rims represents a corrosion event which took place during the
Alpine metamorphism.

amino acid, aspartic acid, has a
particularly high rate of racemization in
very young samples of corals, land snails,
and ostrich eggs (and probably in all
biogenic carbonates). Consequently,
aspartic acid racemization analysis offers
the possibility of dating on time scales of
from years to centuries. Aspartic acid
racemization in the nacreous (inner) layer
of the slit shell Entemnotrochus
adansonianus (a "living fossil," inhabiting
the continental slope) is shown to occur at
a rate sufficiently high for annual
resolution of the age of samples taken
along the growth spiral of the shells, thus
providing information on the organism's
growth rates and longevity. The slit shell
family (Pleurotomariidae) dates back to
the Triassic (c. 200 m.y.), while the
superfamily Pleurotomarioidea originates
in the Cambrian (c. 500 m.y.), not long
after the first mollusks appear in the fossil
record.

The rate of racemization of aspartic
acid was obtained by calibration of D/L
aspartic acid values against ages
determined by 14C analysis of a
post-bomb specimen (collected in 1970) in
the collection of the Smithsonian

92

CARNEGIE INSTITUTION

Iris Inbar and Ron Cohen

Institution. The rapid increase in marine
14C levels from 1958 to 1970, resulting
from thermonuclear bomb tests, enables
shell growth of this period to be dated to
the year. A series of specimens were
collected recently using a Johnson
Sea-Link submersible. Aspartic acid
racemization analysis of these shells
showed that juvenile growth is very rapid
and adult growth 1-2 orders of
magnitude slower. Adulthood is reached
in 2-4 years, and individuals live for an
average of six years (maximum among
nine individuals observed: 13 years). The
life histories of these deep-water living
fossils are thus similar to gastropods that
inhabit shallow water.

Iris Inbar and Ronald E. Cohen: MgO
Under High Pressure and Temperature

We have developed a massively
parallel molecular dynamics code, using
the non-empirical Variation Induced
Breathing (VIB) model, to study the
thermal properties of MgO under
simultaneous high temperatures and
pressures. Supercells of 64 atoms have
been studied with periodic
boundary conditions.

Results from calculated
equations-of-state isotherms for
temperatures up to 3000 K, at
pressures up to 310 GPa, agree
very well with measurements.
Calculated thermodynamic
quantities such as the thermal
expansivity, Griineisen
parameter, thermal pressure,
and bulk modulus, and their
dependence on pressure and
temperature are also in very
good agreement with
experiments. The results suggest
that the thermal properties of
minerals at very high pressure
and temperature could be
represented by constants. The
results were also compared to the
thermal properties of MgO using

the quasi-harmonic approximation: up to
intermediate temperatures of 2000 K, the
results agree very well, indicating that
anharmonicity is not negligible beyond
this point.

D. S. Kelley, T. C. Hoering, and J. D.
Frantz: Methane-Rich Fluids in
Gabbroic Rocks

The fluids associated with
crystallizing igneous rocks are often
trapped as small bubbles or inclusions in
minerals and preserve a record of the
complex chemical and thermal
environment at magmatic temperatures
and continuing down to 200-400°C. The
analysis of individual fluid inclusions in
samples from a 437-meter section of
gabbroic rocks recovered during Ocean
Drilling Program Leg 118 at the
Southwest Indian Ocean Ridge has
revealed a window into a magma
chamber and illuminated the
hydrothermal processes acting at a
slow-spreading ridge environment.

Because of the small size of the
inclusions, there has been no previous
quantitative data on the composition of
them from Layer 3 of the oceanic crust. A
new method, using fast-scanning,
quadrupole mass spectrometry, was
developed at the Geophysical Laboratory
and applied to the analysis of individual
fluid inclusions at the sub-nanogram
level. Fluids released on heating from
100° to 1000°C yielded mass spectra
characteristic of methane, water, C02, and
molecular hydrogen. The bimodal nature
of the spectra is characteristic of fluid
immiscibility and indicates that
end-member fluids contain up to 40 mol
% methane. Isotopic analyses are under
way that may help delineate the origin of
the methane.

Kathleen J. Kingma and Ronald E.
Cohen: Rutile-to-CaCl2 Transition
Observed in Silica at High Pressure

The high-pressure behavior of

GEOPHYSICAL LABORATORY

93

athleen Kingma

stishovite (the densest-known silica
polymorph) is of geophysical interest
because of its importance as a possible
mantle constituent. Since its discovery
three decades ago, a major question has
been whether stishovite transforms to a
denser structure at high
pressures. Of many
suggested forms, the
CaCL: structure is a likely
post-stishovite candidate,
since the transition would
involve only a slight
tilting of the Si06
octahedra that results in a
closer packing than the
ideal rutile structure.

The distortion of the
rutile structure to the
CaCl2 structure has the
same symmetry as the Raman-active Big
soft mode of a rutile-structured phase. In
calculations using the first-principles
linear-augmented plane-wave model
(LAPW), the rutile Big mode is found to
vanish around 75 GPa. Although the
transition is thought to be driven by the
soft Big mode, a shear elastic instability is
induced prior to the vanishing of the soft
mode. Our 1992 LAPW calculations
predict that stishovite will become
unstable at 45 GPa, when the C\\ - Cu
goes to zero. At the phase transition, the
soft mode will become a hard mode of Ag
symmetry, demonstrating that firm
evidence of the stishovite-to-CaCh
transition should be observable in the
Raman spectrum.

We have now examined the
high-pressure vibrational properties of
stishovite by Raman scattering to
pressures in excess of 60 GPa.
Spectroscopic measurements during
room-temperature quasihydrostatic
compression clearly demonstrate that
stishovite transforms to the CaCl2
structure around 50 GPa. At this pressure,
the soft Big stishovite mode turns around
in its pressure dependence and the £g

stishovite mode splits, as predicted for
the transformation to the CaCl2 structure;
the spectral changes are continuous and
completely reversible with no hysteresis.
The excellent agreement between
experiment and LAPW predictions shown
here for stishovite is perhaps one of the
best cases for a quantitative theoretical
prediction of a phase transition to be
experimentally verified.

We have developed a modified
version of the PIB model (PIB++) to
calculate the temperature dependence of
the stishovite-to-CaCl2 transition; such
information is currently unavailable
through experiment. Although the PIB++
model gives a higher transition pressure
of -70 GPa, the room-temperature
pressure dependence of the Raman
modes is reasonable (e.g., the splitting of
the rutile Eg mode at the transition is
accurately reproduced). The transition is
found to be considerably temperature
insensitive — at 2000 K, the transition is
only shifted up in pressure by 10 GPa.
Thus, free silica existing in the deep lower
mantle occurs not only as stishovite, but
also in the CaCL: structure at lower
depths. The elastic instability in stishovite
associated with the transition and the
presence or absence of a seismological
signal gives a bound for the amount of
free silica present in the deep Earth.

Michael J. Walter: Segregation of the
Earth's Core

The segregation of a metallic core
from silicate mantle is perhaps the most
important differentiation event in the
Earth's 4.6-billion-year history. Because of
the inaccessibility of both the core and
most of the Earth's mantle to direct
sampling, little is known about the details
of this grand event.

Siderophile elements have a
preference for metallic phases, and will
have partitioned strongly into the core
upon segregation. If core segregation was
a simple equilibrium process, then this

94

CARNEGIE INSTITUTION

should be reflected in the inventory of
siderophile elements in the silicate
mantle. Rock samples from the Earth's
upper mantle should thus yield relict
information about core formation.

It is known experimentally that many
siderophile elements are too
abundant in the upper mantle
to be accounted for by simple
equilibrium between metal
and silicate at low pressure (1
arm) and low temperature
(1200-1600°C). However, if
the Earth was partially or
completely molten at the time
of metal segregation (a
controversial but theoretically
substantiated possibility), then
metal may have equilibrated
with mantle silicates at very
high temperatures (2000°C) and at high
pressures (1 arm to 100 GPa). In order to
account for the upper mantle budget of
siderophile elements in an equilibrium
segregation process, many siderophile
elements must become significantly less
siderophilic with increase in temperature
and pressure.

To test this model, the partitioning

Michael Walter

behavior of Ni, Co, W, and Mo between
metallic liquid and silicate liquid have
been determined over a range of high
temperatures (1700°-2900°C) and
pressures (1-12 GPa). Experiments have
been performed in piston-cylinder and
multi-anvil apparatus at the
Geophysical Lab and at the
University of Alberta in
conjunction with Yves
Thibault.

The results show that
each of these elements
becomes less siderophilic
with both increasing
temperature and pressure.
However, within the range of
conditions investigated, these
elements are still too
siderophilic to account for
the mantle siderophile element budget by
equilibrium segregation. Is it possible that
the mantle siderophile element budget
reflects equilibrium at even higher
temperatures and pressures than have
been investigated? This question must
await further experimentation, but results
so far do not exclude this possibility.

Bibliography

Reprints of the numbered publications
listed below are available, except where
noted, at no charge from the Librarian,
Geophysical Laboratory, 5251 Broad Branch
Road, N.W., Washington, D.C. 20015-1305,
U.S.A. Please give reprint number(s) when
ordering.

Alberto, H. V., B. O. Mysen, and N. Ayres

de Campos, The structural role of
titanium in silicate glasses: a Raman study
of the system CaO-SiC>2-Ti02, Phys. Chem.
Glasses, in press.

Barruol, G., and A. Souriau, Anisotropy

beneath the Pyrenees from teleseismic
shear wave splitting: results from a test

experiment, Geophys. Res. Lett., in press.

2426 Beaudoin, G., B. E. Taylor, D. Rumble III,
and M. Thiemens, Variations in the sulfur
isotope composition of troilite from the
Canon Diablo meteorite, Geochim. Cos-
mochim. Acta 58, 4253-4255, 1994.

2355 Bertka, C. M., and J. R. Holloway,
Pigeonite at solidus temperatures: im-
plications for partial melting, /. Geophys.
Res. 98, 19755-19766, 1993.

2369 Bertka, C. M., and J. R. Holloway, An-
hydrous partial melting of an iron-rich
mantle. I: Subsolidus phase assemblages
and partial melting phase relations at 10
to 30 kbar, Contrib. Mineral. Petrol. 115,
313-322, 1994.

2370 Bertka, C. M., and J. R. Holloway, An-

GEOPHYSICAL LABORATORY

95

hydrous partial melting of an iron-rich
mantle. II: Primary melt compositions at
15 kbar, Contrib. Mineral. Petrol. 115, 323-
338, 1994.

Bocherens, H., M. L. Fogel, N. Tuross,

and M. Zeder, Trophic structure and
climatic information from isotopic signa-
tures in a Pleistocene cave fauna of south-
ern England, /. Archaeol. Set, in press.

2359 Brenan, J. M., Diffusion of chlorine in
fluid-bearing quartzite: effects of fluid
composition and total porosity, Contrib.
Mineral. Petrol. 115, 215-224, 1993.

2363 Brenan, J., Kinetics of fluorine, chlorine
and hydroxyl exchange in fluorapatite,
Chem. Geol. 110, 195-210, 1994.

2445 Burton, B. P., and R. E. Cohen, Theoreti-
cal study of cation ordering in the system
Pb(Sc1/2Tai/2)03, Ferroelectrics 151, 331-
336, 1994.

Burton, B. P., and R. E. Cohen, First-prin-
ciples study of cation ordering in the sys-
tem Pb(Sc0.5Tao.5)03 and (1 - X)Pb
(Sco.5Tao.5)03-XPbTi03, Ferroelectrics, in
press.

2393 Cohen, R. E., Origin of ferroelectricity in
perovskites: the principal problems from
a theoretical perspective, Ferroelectrics 150,
1-12, 1993.

2375 Cohen, R. E., Electrons, phonons, and
electron-phonon interactions in high-
temperature superconductors, Comput.
Phys. 8, 34-44, 1994.

2446 Cohen, R. E., First-principles phonon
calculations for LiTa03, Ferroelectrics 153,
37^2, 1994.

2429 Cohen, R. E., First-principles theory of
crystalline Si02, in Silica: Physical Beliavior,
Geochemistry and Materials Applications, P.
J. Heaney, C. T. Prewitt, and G. V. Gibbs,
eds., Ch. 11, pp. 369-402, Reviews in
Mineralogy, Vol. 29, Mineralogical Society
of America, Washington, D. C, 1994. (No
reprints available.)

2406 Cohen, R. E., and Z. Gong, Melting and
melt structure at high pressures, in High-
Pressure Science and Technology — 1993, S. C.
Schmidt et al., eds., pp. 379-382, AIP Con-
ference Proceedings 309, American In-
stitute of Physics, New York, 1994.

2427 Cohen, R. E., and Z. Gong, Melting and
melt structure of MgO at high pressures,
Phys. Rev. B 50, 12301-12311, 1994.

2444 Cohen, R. E., M. J. Mehl, and D. A. Papa-
constantopoulos, Tight-binding total-
energy method for transition and noble
metals, Phys. Rev. B 50, 14694-14697, 1994.

2412 Cohen, R. E., L. Stixrude, and D. A. Papa-
constantopoulos, An accurate tight-bind-
ing model for iron at high pressures:

towards high temperature simulations of
the Earth's core, in High-Pressure Science
and Technology — 1993, S. C. Schmidt et al,
eds., pp. 891-894, AIP Conference
Proceedings 309, American Institute of
Physics, New York, 1994.

Downs, R. T, R. M. Hazen, and L. W.

Finger, The high-pressure crystal
chemistry of low albite and the origin of
the pressure dependency of Al/Si order-
disorder, Am. Mineral, in press.

2368 Downs, R. T, and D. C. Palmer, The pres-
sure behavior of a cristobalite, Am.
Mineral. 79, 9-14, 1994.

2440 Drits, V. A., F. Liebau, and C. Prewitt,
Stages of scientific and technical develop-
ment, in Advanced Mineralogy, A. S. Mar-
funin, ed., Vol. 1, Ch. 2.1.1, pp. 38-49,
Springer- Verlag, Berlin and New York,
1994. (No reprints available.)

Duffy, T S., and R. J. Hemley, Tempera-
ture structure of the Earth, in U. S. National
Report to International Union of Geodesy and
Geophysics, in press.

Duffy, T S., C. Meade, Y Fei, H. K. Mao,

and R. J. Hemley, High-pressure phase
transition in Brucite Mg(OH)2, Am.
Mineral., in press.

2378 Duffy, T. S., W. L. Vos, C. S. Zha, R. J.
Hemley, and H. K. Mao, Sound velocities
in dense hydrogen and the interior of
Jupiter, Science 263, 1590-1593, 1994.

2434 Eggert, J. H., R. J. Hemley, and H. K. Mao,
Raman scattering evidence for a new
phase transition in normal deuterium at
high pressures, in Proceedings of the Four-
teenth International Conference on Raman
Spectroscopy, N. Yu and X. Li, eds., pp.
1008-1009, John Wiley & Sons, New York,
1994.

2408 Eggert, J. H., R. J. Hemley, H. K. Mao, and
J. L. Feldman, Rotation-vibration and in-
termolecular dynamics of hydrogen and
deuterium, in High-Pressure Science and
Technology — 1 993, S. C. Schmidt et al, eds.,
pp. 845-848, AIP Conference Proceedings
309, American Institute of Physics, New
York, 1994.

2389 Eggert, J. H., J. Z. Hu, H. K. Mao, L.
Beauvais, R. L. Meng, and C. W. Chu,
Compressibility of the HgBa2Ca„_i
Cu„02n+2+5(ft=T,2,3) high-temperature su-
perconductors, Phys. Rev. B 49, 15299-
15304, 1994.

2384 Eggert, J. H., H. K. Mao, and R. J. Hemley,
Bivibron line widths in solid deuterium at
high pressure, /. Luminescence 58, 328-331,
1994.

2431 Ellis, G. L., and G. A. Goodfriend,
Chronometric and site-formation studies

96

CARNEGIE INSTITUTION

using land snail shells: preliminary
results, in Archeological Investigations on
571 Prehistoric Sites at Fort Hood, Bell and
Coryell Counties, Texas, W. N. Trierweiler,
e<±; pp. 183-201, U.S. Army Fort Hood
Archeological Resource Management
Series Report No. 31, Ft. Hood, Texas,
1994. (No reprints available.)

2432 Engel, M. H., G. A. Goodfriend, Y. Qian,
and S. A. Macko, Indigeneity of organic
matter in fossils: a test using stable isotope
analysis of amino acid enantiomers in
Quaternary mollusk shells, Proc. Natl.
Acad. Sci. USA 91, 10475-10478, 1994.

Fei, Y., Thermal expansion, in Handbook

of Physical Constants, T J. Ahrens, ed.,
American Geophysical Union, Washing-
ton, D.C., in press.

Fei, Y, and H. K. Mao, In situ determina-
tion of the NiAs phase of FeO at high
pressure and temperature, Science, in
press.

2423 Fei, Y, D. Virgo, B. O. Mysen, Y Wang,
and H. K. Mao, Temperature-dependent
electron derealization in (Mg,Fe)Si03
perovskite, Am. Mineral. 79, 826-837, 1994.

Feldman, J. L., J. H. Eggert, J. De Kinder,

R. J. Hemley, H. K. Mao, and D.
Schoemaker, Vibron excitations in solid
hydrogen: a generalized binary random
alloy problem, Phys. Rev. Lett., in press.

2441 Filatov, S. K., and R. M. Hazen, High-
temperature and high-pressure crystal
chemistry, in Advanced Mineralogy, A. S.
Marfunin, ed., Vol. 1, Ch. 2.1.8, pp. 76-89,
Springer- Verlag, Berlin and New York,
1994. (No reprints available.)

Finger, L. W., Minerals at high pressure,

Nucl. Instrum. Methods B, in press.

Finger, L. W., D. E. Cox, and A. P. Jeph-

coat, A correction for powder diffraction
peak asymmetry due to axial divergence,
/. Appl. Crystallogr., in press.

2395 Finger, L. W., R. M. Hazen, R. T. Downs,
R. L. Meng, and C. W. Chu, Crystal
chemistry of HgBa2CaCu206+5 and
HgBa2Ca2Cu308+5: single-crystal X-ray
diffraction results, Physica C 226, 216-221,
1994.

2425 Frantz, J. D., J. Dubessy, and B. O. Mysen,
Ion-pairing in aqueous MgSC>4 solutions
along an isochore to 500°C and 11 kbar
using Raman spectroscopy in conjunction
with the diamond-anvil cell, Chem. Geol.
116, 181-188, 1994.

2418 Gao, L., Y Y Xue, F Chen, Q. Xiong, R.
L. Meng, D. Ramirez, C. W. Chu, J. H.
Eggert, and H. K. Mao, Superconductivity
up to 164 K in HgBa2Cam_1Cuw02m+2+5
(ra=l,2, and 3) under quasihydrostatic

pressures, Phys. Rev. B 50, 4260-4263, 1994.

Gao, L., Y Y Xue, F. Chen, Q. Xiong, R.

L. Meng, D. Ramirez, C. W. Chu, J. H.
Eggert, and H. K. Mao, Universal enhan-
cement of Tc under high pressure in
HgBa2Cam.iCum02m+2+8/ in Proceedings of
the Fourth International Conference, Material
and Mechanisms of Superconductivity, High-
Temperature Superconductors (M2S-HTSC
IV), Grenoble, France, in press.

Gibbs, G. V, M. B. Boisen, Jr., and R. T

Downs, The effect of polarization func-
tions on SiO bond length and SiOSi angle
variations assessed with MP2 electron
correlated wave functions, Phys. Chem.
Minerals, in press.

Giere, R., Formation of REE minerals in

hydrothermal systems, in Rare Earth
Minerals: Chemistry, Origin and Ore
Deposits, A. P. Jones, C. T. Williams, and F
Wall, eds., Chapman & Hall, London, in
press.

2439 Goodfriend, G. A., R. A. D. Cameron,
and L. M. Cook, Fossil evidence of human
impact on the land snail fauna of Madeira,
/. Biogeogr. 21, 309-320, 1994.

Goodfriend, G. A., and P. E. Hare, Reply

to the comment by K. L. F. Brinton and J.
L. Bada on "Aspartic acid racemization
and protein diagenesis in corals over the
last 350 years," Geochim. Cosmochim. Acta,
in press.

Goodfriend, G. A., M. Kashgarian, and

M. G. Harasewych, Aspartic acid race-
mization and the life history of deep-
water slit shells, Geochim. Cosmochim. Acta,
in press.

2411 Hanfland, M., R. J. Hemley, and H. K.
Mao, Synchrotron infrared measurements
of pressure-induced transformations in
solid hydrogen, in High-Pressure Science
and Technology — 2993, S. C. Schmidt et al.,
eds., pp. 877-880, AIP Conference
Proceedings 309, American Institute of
Physics, New York, 1994.

Hanfland, M., R. J. Hemley, and H. K.

Mao, Reply to comment by A. L. Ruof f and
K. Ghandehari on "Optical absorption
measurements on hydrogen at megabar
pressures," Phys. Rev. B, in press.

2356 Hazen, R. M., The New Alchemists: Break-
ing Through the Barriers of High-Pressure
Research, Times Books/Random House,
New York, 1993. (Available at bookstores
or directly from the publisher.)

2443 Hazen, R. M., Matter, high-pressure
phenomena, in Encyclopaedia Brittanica,
1994 edition, Vol. 23, pp. 683-688,
Chicago. (No reprints available.)

2422 Hazen, R. M., The new alchemy, Technol-

GEOPHYSICAL LABORATORY

97

ogy Review 97 (no. 8), 24-32, 1994. (No
reprints available.)

2421 Hazen, R. M., R. T. Downs, P. G. Conrad,
L. W. Finger, and T. Gasparik, Compara-
tive compressibilities of majorite-type
garnets, Phys. Chem. Minerals 21, 344-349,
1994.

2392 Hazen, R. M., R. T. Downs, L. W. Finger,
P. G. Conrad, and T. Gasparik, Crystal
chemistry of Ca-bearing majorite, Am.
Mineral. 79, 581-584, 1994.

2361 Hazen, R. M., R. T. Downs, L. W. Finger,
and J. Ko, Crystal chemistry of ferromag-
nesian silicate spinels: evidence for Mg-Si
disorder, Am. Mineral. 78, 1320-1323, 1993.

2360 Hazen, R. M., L. W. Finger, and J. Ko,
Effects of pressure on Mg-Fe ordering in
orthopyroxene synthesized at 11.3 GPa
and 1600°C, Am. Mineral. 78, 1336-1339,
1993.

2366 Hazen, R. M., D. C. Palmer, L. W. Finger,
G. D. Stucky, W. T. A. Harrison, and T. E.
Gier, High-pressure crystal chemistry and
phase transition of RbTi2(P04)3, /. Phys.
Condens. Matter 6, 1333-1344, 1994.

Hemley, R. J., Properties of matter at high

pressures and temperatures, in History of
the Geosciences: An Encyclopedia, G. A.
Good, ed., Garland Publishing, New York,
in press.

2435 Hemley, R. J., and H. K. Mao, Progress on
hydrogen at ultrahigh pressures, in On
Seminar Volume: Elementary Processes in
Dense Plasmas, S. Ichimaru and S. Ogata,
eds., pp. 269-280, Addison- Wesley, Read-
ing, Mass., 1994.

2428 Hemley, R. J., C. T. Prewitt, and K. J.
Kingma, High-pressure behavior of silica,
in Silica: Physical Behavior, Geochemistry and
Materials Applications, P. J. Heaney, C. T.
Prewitt, and G. V. Gibbs, eds., Ch. 2, pp.
41-81, Reviews in Mineralogy, Vol. 29,
Mineralogical Society of America,
Washington, D.C., 1994.

2390 Hemley, R. J., Z. G. Soos, M. Hanfland,
and H. K. Mao, Charge-transfer states in
dense hydrogen, Nature 369, 384-387,
1994.

Hoch, M. P., M. L. Fogel, and D. L.

Kirchman, Isotope fractionation during
ammonium uptake by marine microbial
assemblages, Geomicrobiol. J., in press.

2407 Hu, J., H. K. Mao, J. Shu, and R. J. Hem-
ley, High-pressure energy dispersive x-
ray diffraction technique with synchro-
tron radiation, in High-Pressure Science and
Technology— 1993, S. C. Schmidt et al, eds.,
pp. 441-444, AIP Conference Proceedings
309, American Institute of Physics, New
York, 1994.

Ilchik, R. P., and D. Rumble III, Sulfur,

carbon and oxygen systematics during
diagenesis and fluid infiltration in the
Creede Caldera, Colorado, in U.S. Geol.
Surv. Open-File Report, R. Bethke, ed., in
press.

Inbar, I., and R. E. Cohen, Origin of fer-

roelectricity in LiTa03 and LiNb03:
LAPW total energy calculations, Fer-
roelectrics, in press.

2447 Irvine, T. N., and J. C. 0. Andersen, In-
cluded blocks (and blocks within blocks)
in the Skaergaard Layered Series, in
Kangerdlugssuaq Studies, Processes at a
Rifted Continental Margin III, C. K. Brooks,
E. Hoch, and A. K. Brantsen, eds., pp.
41-43, Geologisk Museum, Copenhagen,
1992.

2377 Ita, J., and L. Stixrude, Density and elas-
ticity of model upper mantle composi-
tions and their implications for whole
mantle structure, in Evolution of the Earth
and Planets, E. Takahashi, R. Jeanloz, and

D. Rubie, eds., pp. 111-130, American
Geophysical Union and IUGG, Washing-
ton, D.C., 1993. (No reprints available.)

2437 Jeanloz, R., and R. J. Hemley, Ther-
moelasticity of perovskite: an emerging
consensus, Eos, Trans. Am. Geophys. Union
75, 476-477, 1994.

2379 Jephcoat, A. P., J. A. Hriljac, L. W. Finger,
and D. E. Cox, Pressure-induced orienta-
tional order in C6o at 300 K, Europhys. Lett.
25, 429^34, 1994. (No reprints available.)

2381 Kingma, K. J., and R. J. Hemley, Raman
spectroscopic study of microcrystalline
silica, Am. Mineral. 79, 269-273, 1994.

2380 Kingma, K. J., R. J. Hemley, H. K. Mao,
and D. R. Veblen, Reply to comment by L.

E. McNeil and M. Grimsditch on "New
high-pressure transformation in oc-
quartz," Phys. Rev. Lett. 72, 1302, 1994.

2402 Kingma, K. J., R. J. Hemley, D. R. Veblen,
and H. K. Mao, High-pressure crystalline
transformations and amorphization in a-
quartz, in High-Pressure Science and Tech-
nology— 1993, S. C. Schmidt et al, eds., pp.
39^2, AIP Conference Proceedings 309,
American Institute of Physics, New York,
1994.

2398 Koch, P. L., M. L. Fogel, and N. Tuross,
Tracing the diets of fossil animals using
stable isotopes, in Stable Isotopes in Ecology
and Environmental Science, K. Lajtha and R.
H. Michener, eds., pp. 63-92, Blackwell
Scientific Publications, Oxford, England,
1994. (No reprints available.)

2396 Li, X., and H. K. Mao, Solid carbon at
high pressure: electrical resistivity and
phase transition, Phys. Chem. Minerals 21,

98

CARNEGIE INSTITUTION

1-5, 1994.

Mao, H. K., J. H. Eggert, and R. J. Hemley,

Reflectance effects caused by refractive-
index gradients in diamond-anvil cell
samples of H? and Al203, Mod. Phys. Lett.
B, in press.

2383 Mao, H. K., and R. J. Hemley, Material
science at ultrahigh pressures, in Advanced
Materials '94, M. Kamo et a\., eds., pp. 229-
234, National Institute for Research in In-
organic Materials, Tsukuba, Japan, 1994.

2436 Mao, H. K., and R. J. Hemley, Raman
scattering from high pressure solids of
hydrogen and deuterium, in Proceedings of
the Fourteenth International Conference on
Raman Spectroscopy, N. Yu and X. Li, eds.,
pp. 828-829, John Wiley & Sons, New
York, 1994.

2391 Mao, H. K., and R. J. Hemley, Ultrahigh-
pressure transitions in solid hydrogen,
Rev. Mod. Phys. 66, 671-692, 1994.

2414 Mao, H. K., R. J. Hemley, and A. L. Mao,
Recent design of ultrahigh-pressure
diamond cell, in High-Pressure Science and
Technology — 1993, S. C. Schmidt et al., eds.,
pp. 1613-1616, AIP Conference Proceed-
ings 309, American Institute of Physics,
New York, 1994.

2386 Mao, H. K., J. Shu, J. Hu, and R. J. Hem-
ley, High-pressure X-ray diffraction study
of diaspore, Solid State Commun. 90, 497-
500, 1994.

2417 Marton, F. C, and R. E. Cohen, Predic-
tion of a high-pressure phase transition in
A1203, Am. Mineral. 79, 789-792, 1994.

McMillan, P. E, J. Dubessy, and R. Hem-
ley, Application to earth, planetary and
environmental sciences, in Raman Micros-
copy, M. Delhaye, ed., in press.

2397 Meade, C, Solid Earth: mantle and core
studies, Geotimes 39 (no. 2), 36-37, 1994.
(No reprints available.)

2394 Meade, C, J. A. Reffner, and E. Ito,
Synchrotron infrared absorbance meas-
urements of hydrogen in MgSiOa
perovskite, Science 264, 1558-1560, 1994.

Mehl, M. J., D. A. Papaconstantopoulos,

R. E. Cohen, and M. M. Sigalas, First-prin-
ciples tight-binding total energy calcula-
tions for metals, in Alloy Modeling and
Design, G. M. Stock, ed., Minerals, Metals
& Materials Society, Warrendale, Perm., in
press.

Meng, Y, Y Fei, D. J. Weidner, and G. D.

Gwanmesia, Hydrostatic compression of
y-Mg2Si04 to mantle pressures and 700 K:
constraints on the thermal equation of
state and the related thermoelastic proper-
ties, Phys. Chem. Minerals, in press.

Morse, S. A., and H. S. Yoder, Jr., Melting

and phase transitions of RbCl to 10
kilobars, Geophys. Res. Lett., in press.

My sen, B., Silicate melts and glasses: the

influence of temperature and composition
on the structural behavior of anionic
units, in K. Yagi 80th Birthday Commemora-
tion Volume, A. Gupta, ed., Indian
Academy of Sciences, in press.

Mysen, B. O., Structural behavior of Al3+

in silicate melts: in-situ, high-temperature
measurements as a function of bulk
chemical composition, Geochim. Cos-
mochim. Acta, in press.

2382 Mysen, B. O., and J. D. Frantz, Structure
of haplobasaltic liquids at magmatic
temperatures: in situ, high-temperature
study of melts on the join Na2Si205-
Na2(NaAl)205, Geochim. Cosmochim. Acta
58, 1711-1733, 1994.

2399 Mysen, B. O., and J. D. Frantz, Silicate
melts at magmatic temperatures: in-situ
structure determination to 1651°C and ef-
fect of temperature and bulk composition
on the mixing behavior of structural units,
Contrib. Mineral. Petrol. 117, 1-14, 1994.

Mysen, B., and D. Neuville, Effect of

temperature and Ti02 content on the
structure of Na2Si205-Na2Ti205 melts and
glasses, Geochim. Cosmochim. Acta, in
press.

2442 Mysen, B. O., and D. Virgo, Structure
and properties of silicate glasses and
melts; theories and experiment, in Ad-
vanced Mineralogy, Vol. 1, Ch. 4.1, A. S.
Marfunin, ed., pp. 238-253, Springer- Ver-
lag, Berlin and New York, 1994. (No
reprints available.)

2387 Nagahara, H., I. Kushiro, and B. O.
Mysen, Evaporation of olivine: low pres-
sure phase relations of the olivine system
and its implications for the origin of
chondritic components in the solar
nebula, Geochim. Cosmochim. Acta 58,
1951-1963, 1994.

2415 Nagahara, H., I. Kushiro, and B. O.
Mysen, Vaporization and condensation of
chondritic materials — experimental
studies, in Primitive Solar Nebula and
Origin of Planets, H. Oya, ed.,pp. 427^46,
Terra Scientific Publishing Company
(TERRAPUB), Tokyo, 1993. (No reprints
available.)

2419 Paerl, H. W., and M. L. Fogel, Isotopic
characterization of atmospheric nitrogen
inputs as sources of enhanced primary
production in coastal Atlantic Ocean
waters, Mar. Biol. 119, 635-645, 1994.

Paerl, H. W., M. L. Fogel, and P. W. Bates,

Atmospheric nitrogen deposition in coas-
tal waters: implications for marine

GEOPHYSICAL LABORATORY

99

primary production and C flux, in Proceed-
ings of the 6th International Microbial Ecology
Symposium, Barcelona, Spain, C. Pedros-
Alio, ed., ASM Publications, in press.

Paerl, H. W., M. L. Fogel, P. W. Bates, and

P. M. O'Donnell, Is there a link between
atmospheric nitrogen deposition and eu-
trophication in coastal waters?, in Proceed-
ings of the 6th International ERF/ESCA Sym-
posium, September 1992, Plymouth, U.K., K.
L. Dyer, ed., Olsen and Olsen, Ltd., in
press.

2367 Palmer, D. C, and L. W. Finger, Pressure-
induced phase transition in cristobalite: an
X-ray powder diffraction study to 4.4 GPa,
Am. Mineral. 79, 1-8, 1994.

Palmer, D. C, R. J. Hemley, and C. T.

Prewitt, Raman spectroscopic study of
high-pressure phase transitions in cris-
tobalite, Phys. Chem. Minerals, in press.

2376 Pearson, D. G., F. R. Boyd, S. E. Haggerty,
J. D. Pasteris, S. W. Field, P. H. Nixon, and
N. P. Pokhilenko, The characterisation and
origin of graphite in cratonic lithospheric
mantle: a penological carbon isotope and
Raman spectroscopic study, Contrib.
Mineral. Petrol. 115, 449-466, 1994. (No
reprints available.)

Pearson, D. G., R. W. Carlson, S. B. Shirey,

F. R. Boyd, and P. H. Nixon, The stabilisa-
tion of Archaean lithospheric mantle: a
Re-Os isotope study of peridotite
xenoliths from the Kaapvaal and Siberian
cratons, Earth Planet. Sci. Eett., in press.

Pearson, D. G., S. B. Shirey, R. W. Carlson,

F. R. Boyd, N. P. Pokhilenko, and N.
Shimizu, Re-Os, Sm-Nd and Rb-Sr isotope
evidence for thick Archaean lithospheric
mantle beneath the Siberian craton
modified by multi-stage metasomatism,
Geochim. Cosmochim. Acta, in press.

Popp, R. K., D. Virgo, H. S. Yoder, Jr., T.

C. Hoering, and M. W. Phillips, An ex-
perimental study of phase equilibria and
oxy- component in kaersutitic amphibole:
implications for the /h2 and aHlo in the
upper mantle, Am. Mineral, in press.

2404 Qadri, S. B., E. F. Skelton, A. W. Webb,
and J. Z. Hu, Pressure induced polymor-
phism of ZnTe, in High-Pressure Science and
Technology — 2993, S. C. Schmidt et al., eds.,
pp. 319-322, AIP Conference Proceedings
309, American Institute of Physics, New
York, 1994.

2405 Qadri, S. B., E. F. Skelton, A. W. Webb, J.
Z. Hu, and J. K. Furdyna, Pressure induced
phase transition of Zni_xCoxSe, in High-
Pressure Science and Technology — 2993, S. C.
Schmidt et al, eds., pp. 347-349, AIP Con-
ference Proceedings 309, Amer-ican In-
stitute of Physics, New York, 1994.

Qian, Y, M. H. Engel, G. A. Goodfriend,

and S. A. Macko, Abundance and stable
carbon isotope composition of amino
acids in molecular weight fractions of fos-
sil and artificially aged mollusk shells,
Geochim. Cosmochim. Acta, in press.

2388 Reffner, J., G. L. Carr, S. Sutton, R. J.
Hemley, and G. P. Williams, Infrared
microspectroscopy at the NSLS, Synchro-
tron Radiation News 7 (no. 2), 30-37, 1994.

2372 Reichlin, R., A. K. McMahan, M. Ross, S.
Martin, J. Hu, R. J. Hemley, H. K. Mao, and
Y Wu, Optical, x-ray, and band-structure
studies of iodine at pressures of several
megabars, Phys. Rev. B 49, 3725-3733, 1994.

2374 Richet, P., J. Ingrin, B. O. Mysen, P. Cour-
tial, and P. Gillet, Premelting effects in
minerals: an experimental study, Earth
Planet. Sci. Eett. 121, 589-600, 1994. (No
reprints available.)

Rumble, D., Water circulation in meta-

morphism, /. Geophys. Res., in press.

2420 Rumble, D., Ill, and T. C. Hoering, Anal-
ysis of oxygen and sulfur isotope ratios in
oxide and sulfide minerals by spot heating
with a carbon dioxide laser in a fluorine
atmosphere, Accounts Chem. Res. 27, 237-
241, 1994.

2357 Saxena, S. K., N. Chatterjee, Y Fei, and G.
Shen, Thermodynamic Data on Oxides and
Silicates: An Assessed Data Set Based on
Thermochemistry and High Pressure Phase
Equilibrium, Springer- Verlag, New York,
1993. (Available directly from the publish-
er.)

2371 Shen, G., Y. Fei, U. Halenius, and Y.
Wang, Optical absorption spectra of
(Mg,Fe)Si03 silicate perovskites, Phys.
Chem. Minerals 20, 478^82, 1994.

2365 Sillen, A., and T. C. Hoering, Chemical
characterization of burnt bones from
Swartkrans, in Swartkrans, A Cave's
Chronicle of Early Man, C. K. Brain, ed., pp.
243-249, Transvaal Museum Monograph
No. 8, Pretoria, South Africa, 1993.

2401 Skelton, E. F., A. R. Drews, M. S. Osofsky,
S. B. Qadri, J. Z. Hu, T. A. Vanderah, J. L.
Peng, and R. L. Greene, Direct observation
of microscopic inhomogeneities with
energy-dispersive diffraction of synchro-
tron-produced x-rays, Science 263, 1416-
1418, 1994. (No reprints available.)

Stafford, T. S., M. L. Fogel, K. Brendel,

and P. E. Hare, Late Quaternary paleoecol-
ogy of the southern high plains based on
stable nitrogen and carbon isotope
analysis of fossil Bison collagen, in The
Archaic of the Southern North American
Deserts, H. Shafer, D. L. Carlson, and K. D.
Sobolik, eds., Texas A&M Press, College
Station, in press.

100

CARNEGIE INSTITUTION

2338 Stixrude, L., and R. E. Cohen, Stability of
orthorhombic MgSiOi perovskite in the
Earth's lower mantle, Nature 364, 613-616,
1993.

2413 Stixrude, L. and R. E. Cohen, First prin-
ciples investigation of bcc, fee, and hep
phases of iron, in High-Pressure Science and
Technology — 1993, S. C. Schmidt et al., eds.,
pp. 911-914, AIP Conference Proceedings
309, American Institute of Physics, New
York, 1994.

Stixrude, L., and R. E. Cohen, Con-
straints on the crystalline structure of the
inner core: mechanical instability of bcc
iron at high pressure, Geophys. Res. Lett., in
press.

2424 Stixrude, L., R. E. Cohen, and D. J. Singh,
Iron at high pressure: linearized-aug-
mented-plane-wave computations in the
generalized-gradient approximation,
Phys. Rev. B 50, 6442-6445, 1994.

Taylor, R. E., P. E. Hare, and T D. White,

Geochemical criteria for thermal altera-
tion of bone, /. Archaeol. Sci., in press.

2433 Tsoar, H., and G. A. Goodfriend,
Chronology and paleoenvironmental in-
terpretation of Holocene aeolian sands at
the inland edge of the Sinai-Negev erg,
The Holocene 4 (no. 3), 244-250, 1994.

2430 Tuross, N., and M. L. Fogel, Exceptional
molecular preservation in the fossil
record: the archaeological, conservation,
and scientific challenge, in Archaeometry of
Pre-Columbian Sites and Artifacts, D. A.
Scott and P. Meyers, eds., pp. 367-380,
Getty Conservation Institute, Marina Del
Rey, Calif., 1994. (No reprints available.)

2416 Tuross, N., and M. L. Fogel, Stable iso-
tope analysis and subsistence patterns at
the Sully Site, South Dakota, in Skeletal
Biology in the Great Plains: Migration, War-
fare, Health, and Subsistence, D. W. Owsley
and R. Jantz, eds., pp. 283-289, Smith-
sonian Institution Press, Washington,
D.C., 1994. (No reprints available.)

2385 Tuross, N., M. L. Fogel, L. Newsom, and
G. H. Doran, Subsistence in the Florida
Archaic: the stable isotope and ar-
cheobotanical evidence from the Wind-
over Site, American Antiquity 59, 288-303,

1994. (No reprints available.)

Vos, W. L., Helium compounds, in Mc-
Graw-Hill Yearbook of Science and Technology

1 995, in press.

2354 Vos, W. L., L. W. Finger, R. J. Hemley, and
H. K. Mao, Novel H2-H20 clathrates at
high pressures, Phys. Rev. Lett. 71, 3150-
3153, 1993.

2409 Vos, W. L., L. W. Finger, R. J. Hemley, H.
K. Mao, and H. S. Yoder, Jr., Phase be-
havior of H2-H20 at high pressure, in
High-Pressure Science and Technology —
2993,S. C. Schmidt etal, eds., pp. 857-860,
AIP Conference Proceedings 309,
American Institute of Physics, New York,
1994.

2358 Williams, Q., R. J. Hemley, M. B. Kruger,
and R. Jeanloz, High-pressure infrared
spectra of a-quartz, coesite, stishovite and
silica glass, /. Geophys. Res. 98, 22157-
22170, 1993.

2373 Yochelson, E. L., and H. S. Yoder, Jr.,
Founding the Geophysical Laboratory,
1901-1905: a scientific bonanza from per-
ception and persistence, Geol. Soc. Am.
Bull. 106, 338-350, 1994.

2364 Yoder, H. S., Jr., Development and
promotion of the initial scientific program
for the Geophysical Laboratory, in The
Earth, the Heavens, and the Carnegie Institu-
tion of Washington, G. A. Good, ed., pp.
21-28, American Geophysical Union,
Washington, D.C., 1994.

Yoder, H. S., Jr., J. Frank Schairer, April

13, 1904-September 26, 1970, in Biographi-
cal Memoirs of the National Academy of Scien-
ces, Vol. 66, National Academy Press,
Washington, D.C., in press.

2410 Zha, C. S., T. S. Duffy, H. K. Mao, and R.
J. Hemley, High-pressure Brillouin scat-
tering and elastic constants of single-crys-
tal hydrogen to 24 GPa, in High-Pressure
Science and Technology — 1993, S. C.
Schmidt et ah, eds., pp. 873-876, AIP Con-
ference Proceedings 309, American In-
stitute of Physics, New York, 1994.

2403 Zha, C. S., R. J. Hemley, H. K. Mao, T S.
Duffy, and C. Meade, Brillouin scattering
of silica glass to 57.5 GPa, in High-Pressure
Science and Technology — 1993, S. C.
Schmidt et al, eds., pp.^ 93-96, AIP Con-
ference Proceedings 309, American In-
stitute of Physics, New York, 1994.

2438 Zha, C. S., R. J. Hemley, H. K. Mao, T. S.
Duffy, and C. Meade, Acoustic velocities
and refractive index of Si02 glass to 57.5
GPa by Brillouin scattering, Phys. Rev. B
50, 13105-13112, 1994.

2400 Zhang, H., W. B. Daniels, and R. E.
Cohen, Exciton energy and its pressure
dependence in alkali halides, Phys. Rev. B
50, 70-74, 1994.

2362 Zhang, J., R. C. Liebermann, T. Gasparik,
C. T. Herzberg, and Y. Fei, Melting and
subsolidus relations of Si02 at 9-14 GPa,
/. Geophys. Res. 98, 19785-19793, 1993.

GEOPHYSICAL LABORATORY

101

Personnel

Research Staff

Francis R. Boyd, Jr.

Ronald E. Cohen

Larry W. Finger

Marilyn L. Fogel

John D. Frantz

P. Edgar Hare

Robert M. Hazen

Russell J. Hemley

Thomas C. Hoering

T. Neil Irvine

Ho-kwang Mao

Bjorn O. Mysen

Charles T. Prewitt, Director

Douglas Rumble III

David Virgo

Hatten S. Yoder, Jr., Director Emeritus

Cecil and Ida Green Senior Fellow

Frank Press1-2

Jon H. Eggert, CHiPR Associate

Reto Giere, Swiss National Science Fellow6

Alexandre Goncharov, Carnegie Fellow11

Michael E. Hanfland, NSF Associate12

Robert P. Ilchik, NSF Associate

Iris Inbar, Office of Naval Research

Associate13
Ming Li, CHiPR Associate14
Daniel R. Neuville, Carnegie and French

Centre National de la Recherche

Scientifique Fellow15
Raymond M. Russo, Harry Oscar Wood

Fellow1'16
Jinfu Shu, CHiPR Associate
Larry Solheim, Carnegie Fellow1-17
Madduri S. Somayazulu, NSF Associate18
Jouri Timofeev, NSF Associate19
Willem L. Vos, CHiPR Associate16
Michael J. Walter, CHiPR Associate20
Edward D. Young, Carnegie Fellow21
John C. VanDecar, Harry Oscar Wood

Fellow1-22

Senior Fellows and Associates

Predoctoral Fellozvs and Associates

Peter M. Bell, Adjunct Senior Research

Scientist
Constance Bertka, National Aeronautics and

Space Administration (NASA) and Center

for High Pressure Research (CHiPR)

Associate3
Paula Davidson, Department of Energy

(DOE) Associate4
Yingwei Fei, Norton Senior Fellow
Glenn A. Goodfriend, Senior Postdoctoral

Associate (National Science Foundation,

NSF, Associate)5
Jingzhu Hu, Research Technician (NSF)6
Mark D. Kluge, Research Physicist (NSF)7
Charles Meade, NSF and CHiPR Associate
Chang-Sheng Zha, Research Technician

(CHiPR)6

Postdoctoral Fellows and Associates

Carmen Aguilar, NSF Associate

Guilhem Barruol, NSF Associate and Bourse

Lavoisier Fellow, French Ministry of

Foreign Affairs1-8
David R. Bell, DOE Associate
Herve Bocherens, Carnegie Fellow9
Andrew J. Campbell, Carnegie Fellow
Robert T. Downs, NSF Associate
Thomas S. Duffy, Grove Carl Gilbert

Fellow1-10

Pamela G. Conrad, Carnegie Fellow4
Jens Christian 0. Andersen, Fulbright

Fellow23
Beverly Johnson, Carnegie Fellow24
Kathleen Kingma, CHiPR Associate10
Julie Kokis, NSF Associate

Research Interns

Aaron Andalman, Blair High School25
Beth A. Bailey, George Washington

University26
Claude Banta, Bethesda Chevy Chase High

School25
Thomas R. Cooper, George Washington

University27
Marc Hudacsko, Blair High School25
Felice Segura, Georgetown Day School28
Stacy Shinneman, George Washington

University28
Sujoy Tagore, Blair High School25
Wendy E. Walker, Long Island University29
Joshua Weitz, Princeton University30
Emily Yourd, George Washington

University31

Supporting Staff

John R. Almquist, Library Volunteer
Andrew J. Antoszyk, Shop Foreman

102

CARNEGIE INSTITUTION

Maceo T Bacote, Engineering Apprentice1'32
Gary Bors, Building Engineer1'33
Bobbie L. Brown, Instrument Maker
Stephen D. Coley, Sr., Instrument Maker
H. Michael Day, Facilities Manager1
Roy R. Dingus, Building Engineer1
Pablo D. Esparza, Maintenance Technician132
David J. George, Electronics Technician
Christos G. Hadidiacos, Electronics Engineer
Shaun J. Hardy, Librarian1
Marjorie E. Imlay, Assistant to the Director
Mikie Ishikawa, Library Volunteer
William E. Key, Building Engineer1
D. Carol Lynch, Executive Secretary1'34
Paul Meeder, Administrative Assistant17
Lawrence B. Patrick, Maintenance

Technician1
Pedro J. Roa, Maintenance Technician1
Roy E. Scalco, Engineering Apprentice1
Susan A. Schmidt, Coordinating Secretary
Fiorella V. Simoni, Laboratory Technician35
John M. Straub, Business Manager
Stephanie Vogelpohl, Administrative

Assistant29
Mark Wah, Instrument Maker
Merri Wolf, Library Technical Assistant1
Karen Young, Laboratory Technician21

Visiting Investigators

Nabil Z. Boctor, Washington, D.C.
Alison Brooks, George Washington
University

John V. Badding, Pennsylvania State

University
Benjamin P. Burton, National Institute of

Standards and Technology
Jean Dubessy, Centre de Recherches sur La

Geologie des Matieres Premieres

Minerales et Energetiques,

Vandoeuvre-Les-Nancy, France
Joseph Feldman, National Research

Laboratory
Donald G. Isaak, University of California,

Los Angeles
Deborah Kelley, University of Washington
Allison M. Macfarlane, George Mason

University
Kevin Mandernack, Scripps Institution of

Oceanography
Frederic Marton, Northwestern University
Nicolai P. Pokhilenko, Institute of

Mineralogy and Petrology, Novosibirsk,

Russia
Robert Popp, Texas A&M University
Nicholas M. Rose, Geological Museum,

Copenhagen, Denmark
Nicolai V. Sobolev, Director of the Institute

of Mineralogy and Petrology, Academy of

Sciences, Novosibirsk, Russia
Christopher Talbot, University of Uppsala,

Sweden
Noreen C. Tuross, Smithsonian Institution
David von Endt, Smithsonian Institution
Willem L. Vos, University of Amsterdam,

The Netherlands

Joint Appointment with
Department of Terrestrial
Magnetism
2From September 15, 1993
3From May 1, 1994
4From December 1, 1993
5FromJuly 1,1993
6From January 1,1994
7From April 9, 1994
8From October 10, 1993
9To September 30, 1993
10To June 30, 1994
nFrom December 21, 1993
12To December 21, 1993
13From October 1, 1993
14From October 1, 1993
15To January 15, 1994
16To December 1, 1993
17From September 1, 1993

22

18From March 17, 1994
19From January 17 to June 1, 1994
20From September 30, 1993
01To June 14, 1994

From September 28, 1993
23To May 23, 1994
24To January 31, 1994
25From June 22, 1994
26To July 31, 1993
27From June 15, 1994
28From March 20,1994
29To August 31, 1993
30From June 1, 1994
31From May 26, 1994
32From May 16, 1994
33To April 8, 1994
34From September 24, 1993
35From January 13, 1994

Department of Terrestrial

Magnetism

Mike Seemann, left, and Glenn Poe

m .-,

^LiSHyyfi'**^

•* c&

^^^^^^3^^SiSi31^^

DTM staff near the main building, Broad Branch Road campus, spring 1994. First
row (left to right): David Kuentz, Janice Dunlap, Rosa Maria Esparza, George
Wetherill, Lanbo Liu, Glenn Poe, Georg Bartels, Mikie Ishikawa, Pablo Esparza, Pedro
Roa. Second row: Sandra Keiser, Vera Rubin, Louis Brown, Merri Wolf, Ben Pandit,
Nelson McWhorter, Roy Dingus, Maceo Bacote, Raymond Russo, Lori Herold, Shaun
Hardy, Frank Press. Third row: Erik Hauri, Tsuyoshi Ishikawa, Richard Carlson, David
James, Selwyn Sacks, John Graham, Fouad Tera, Frangois Schweizer, Guilhem
Barruol, John Almquist, Prudence Foster, Harold Butner, Mary Coder. Last row: Terry
Stahl, Roy Scalco, David Weinrib, Sean Solomon, Ragnar Stefansson, Michael Day,
William Key, Alan Boss, Paul Silver, Ingi Bjamason, John VanDecar.

The Director's Introduction

History, as it lies at the root of all science, is

also the first distinct product of man's

spiritual nature; his earliest expression of

what can be called Thought.

Thomas Carlyle
On History (1830)

As British historian and essayist Thomas Carlyle recognized, all
scientists are to some extent historians. This generalization is
particularly apt for earth scientists and astronomers. By means
of starlight millions to billions of years in transit or minute quantities of
a radioactive isotope with a half-life measured in billions of years, we
search for an ever-improved understanding of the processes governing
the behavior of galaxies, stars, and the solar system. The objects of our
study are by their very nature evolving, at times violently, and the
challenge to the historians of such objects is to sift through the residue
of past events within our observational and intellectual grasp and to
distill the most important themes. Although the physical world is
known to exhibit stochastic and chaotic behavior, there is nonetheless
an overarching optimism among earth and space scientists that
common physical and chemical laws underlie all phenomena, and that
these laws provide a basis for hypothesis formulation, quantitative
prediction, and rejection of false hypotheses. While the histories we
write are always imperfect, there is a shared method that binds all of
our efforts.

The two essays that follow exemplify earth and planetary science
as history. The first, by Richard Carlson, Steven Shirey, former DTM
Fellow Graham Pearson, and Geophysical Laboratory collaborator F. R.
Boyd, summarizes recent work on the nature of the mantle beneath the

105

106 CARNEGIE INSTITUTION

Earth's continents. Continents are generally characterized by a much
greater thickness of low-density crust than oceanic regions. As a result,
the lithosphere or tectonic plate beneath continents is too buoyant to
participate significantly in the subduction process that recycles oceanic
lithosphere into the deeper mantle, and parts of the continental crust
are billions of years old. The oldest continental crust has also been
remarkably stable with respect to tectonic deformation and disruption.
An important clue to the mechanism of this stability is the evidence
from seismology that continental crust is underlain by a mantle
lithospheric root of anomalous seismic velocities 200 km or more thick.

By a fortune of nature, samples of these continental roots have been
ripped from their lithospheric resting places and carried to the surface
during the volcanic eruptions of magmas generated from still greater
depths, and these samples are available for detailed geochemical
analyses in the laboratory. Carlson and colleagues, by the application of
Re-Os isotope systematics, have demonstrated that the time of removal
of Re (probably by partial melting) in such mantle samples from South
Africa and Siberia is about the same as the 3-3.5-billion-year age of the
crustal rocks near their respective eruption sites. Their result indicates
that much of the roots of ancient continents formed at the same time as
the crust to which they are attached. It therefore appears that it is the
strength of the unusually thick lithosphere that has provided the oldest
continental blocks with their long-lived stability. The mechanism by
which these deep roots formed is not known, but Carlson and
colleagues offer the intriguing suggestion that they arose not by plate
tectonic processes but by the removal of large melt fractions during the
ascent of hot plumes from the underlying mantle, plumes early in the
Earth's history that may have been hotter or more vigorous than their
more modern counterparts.

The second essay reviews recent work by my students and me on
the tectonic evolution of Venus. Once known as our sister planet, Venus
offers a telling example of how the gaps in our understanding of the
processes that have governed the evolution of the Earth are brought
into stark focus by new information. Prior to the Magellan mission,
whose cloud-penetrating radar provided the first high-resolution
global images of the surface of Venus, competing hypotheses for the
tectonic and volcanic evolution of planet Venus were strongly
geomorphic, variants of either plate tectonics or a widespread system
of mantle plumes. Instead the Magellan images, and data more recently
acquired from Magellan on the planet's gravity field, point to at least
two distinct eras in the geological history of the planet, neither of them
plate-like or plume-like. In the earlier of the two eras, the lithosphere
was able to deform so pervasively as to render the surface a nearly
unreadable complex of faults and folds, and volcanism was
widespread. In the younger and present era, in striking contrast, the

TERRESTRIAL MAGNETISM 107

lithosphere shows signs of great strength, and deformation and
volcanism are localized to a few regions constituting a small fraction of
the surface area. Whether these patterns have repeated throughout the
history of Venus and, if so, on what time scale, are matters of debate
and ongoing research, but it is a sobering lesson that apparently modest
differences in the conditions at the surface or at the outset of evolution
have pushed Venus and Earth onto two strongly contrasting paths.

As the Earth and the planets evolve by processes both gradual and
abrupt, so too do institutions. At DTM, the course of our research can
be changed significantly by an unusual natural event. Two such events
punctuated the end of the year just past.

In June, two portable broadband seismic experiments were in
progress in South America, one led by David James aimed toward
probing the deep structure of the ancient continental lithosphere of
Brazil, and one led by Paul Silver designed to image the structure and
define the large-scale tectonics of the subduction zone and active
mountain belts of Bolivia and Chile. On June 9, 1994, the largest deep
earthquake ever recorded occurred beneath Bolivia. The fortuitously
sited DTM seismic stations are providing unique data on the nature of
that unusual event, and more generally on the mechanism of deep
earthquakes and the nature of mantle convective flow beneath western
South America.

One month after that earthquake, the fragments of comet
Shoemaker-Levy 9 crashed into the upper atmosphere of Jupiter,

- Pm^MMfi^^wi^Ai^;:. ■■■: . :

David James (far right), Randy Kuehnel (center), and Marcelo Assumpcao of the
University of Sao Paulo, Brazil, service a portable broadband seismic station in
Olimpia, Sao Paulo State, Brazil. The station is part of an array of seismic stations
installed to study deep lithosphere structure beneath the ancient continental shield
of South America.

108 CARNEGIE INSTITUTION

providing for the first time an opportunity to observe the effects of a
large impact on another planetary body. Among the many astronomers
who made observations of those impacts were DTM's David
Rabinowitz and Harold Butner, who watched events unfold on the
2.5-m du Pont telescope at Las Campanas. Despite generally
cloud-covered night skies, they made observations of comet fragments
a few days prior to impact that show evidence for ongoing
fragmentation and the development of dust trails emanating from each
fragment and pointing in the direction of Jupiter. Their findings have
helped to establish precise impact times and may yield new insight into
the interaction of fine dust particles with the Jovian magnetosphere.

The most critical influence on the history of a department comes
from the movement of individuals, and DTM experienced several
notable transitions in the last year. Julie Morris accepted a position as
research associate professor at Washington University and resigned
from the DTM research staff at the end of 1993. Louis Brown retired
from the research staff and was made an emeritus staff member as of
the end of January 1994, although the passage was marked by no break
in the stride of either his work or his daily schedule. In response to the
resulting vacancies, two new appointments were made to the research
staff: Erik Hauri in geochemistry and Conel Alexander in
cosmochemistry. Each brings to the department a high level of energy,
an unusual breadth, and an exciting research agenda.

Erik Hauri, trained in marine geology and geochemistry, has
focused his research on the geochemistry of the Earth's mantle. He has
chosen oceanic island basalts and the nodules of mantle material they
sometimes contain as his windows to such broader issues as the nature
and origin of mantle heterogeneity and the relationships among mantle
dynamics, melting, and geochemical mixing. Even as a graduate
student, he brought a remarkable diversity of skills to bear on his
research problems, ranging from analytical trace-element and isotope
geochemistry, to theoretical fluid dynamics, to experimental
high-temperature and high-pressure measurements of the partitioning
of diagnostic elements between melt and the minerals remaining in the
mantle residue. Since arriving at DTM, Hauri has led the Department's
efforts to acquire an ion microprobe, an instrument that permits the
measurement and imaging in situ of trace-element concentrations and
isotope ratios in rock and mineral samples at a spatial resolution as
small as 1 urn.

Conel Alexander's most visible research to date has been on the
nature and origin of small meteorite inclusions of carbon, carbides, or
oxides having anomalous isotope ratios tagging them as Stardust
surviving from a time before the formation of the solar nebula. The
search for these once interstellar grains involves careful chemical
separation techniques and ion probe analysis, and an interpretation of

Sean Solomon (center) with new staff members Erik Hauri (left) and Conel
Alexander in the geochemistry building mass spectrometer laboratory.

the isotope anomalies requires an understanding of the nuclear
reactions and astrophysical processes in the classes of stars from which
the grains might have originated. With degrees in both geology and
physics, Alexander brings a fluency with both the geochemical and the
astrophysical aspects of this search. His research interests also include
the formational mechanisms and chemistry of chondritic meteorites,
and the chemical identification of cometary and asteroidal sources of
interplanetary dust particles collected in the Earth's stratosphere.

Whether the pursuit of answers to basic questions about the origin
and evolution of the Earth and the cosmos is, as Carlyle saw history, an
expression of "man's spiritual nature," is a matter for the philosophers.
The typical individual scientist is driven more by an enjoyment of the
chase and the satisfaction of learning something new than by any sense
of spiritual imperative. At a time when "curiosity-driven research" is
out of vogue with many of those elected or appointed to formulate and
implement national science policy, such research forms the backbone of
the Carnegie Institution. For those of us fortunate enough to be
chartered by this institution to follow our own curiosities, it is
incumbent upon us to direct that pursuit toward problems both
fundamental in nature and amenable to substantial progress.

— Sean C. Solomon

The Mantle Beneath Continents

by Richard W. Carlson, Steven B. Shirey,
D. Graham Pearson, and F. R. Boyd

Inspired in part by the puzzle-piece fit of western Africa with
eastern South America, the theory of continental drift and its driving
mechanism, plate tectonics, provides a unified theory to explain many
surface features of Earth. Though continents and the shape of their

110

CARNEGIE INSTITUTION

boundaries played a large role in the formulation of plate tectonic
thought, continents themselves are not obvious products of the plate
tectonic process. In plate tectonic interpretations, continents are
believed to form as amalgamations of the thickened volcanic crusts
created above subduction zones, where oceanic plates descend into the
interior. But in fact, the volcanic products of those subduction zones
situated purely within ocean basins are not similar in their
major-element composition to average continental crust. Thus, if
continents form by accumulation of subduction-related volcanism, an
additional step of chemical processing not clearly related to plate
tectonics is required to produce the continents we observe today.

An unusual feature of the continents, particularly the oldest
sections of the continents known as cratons, is that they seem to be
underlain by deep "keels" of mantle distinguished by fast seismic
velocities (and strong seismic anisotropy, as described by Paul Silver in
Year Book 91, pp. 66-78). Fast seismic velocities are a signature of cold
mantle. What is unexpected about these keels is that this cold mantle
remains attached to the overlying continent. One would suppose that
cold dense mantle should either delaminate from the buoyant crust and
sink back into the underlying mantle or pull the crust down with it, as
it does the oceanic crust in subduction zones.

These observations pose many questions. Did the thick keels form
purely by conductive cooling from above? Why hasn't the cold mantle
broken away from the continent or caused the continent to subduct?
What characteristic causes the mantle keel to be dynamically stable
beneath continents? Do the keels play some role in the long-term
stability of continental crust and perhaps in determining its chemical
distinctions from oceanic crust? Does the presence of a thick mantle

Left to right: Steven Shirey, F. R. (Joe) Boyd, and Richard Carlson, with an
unusually large xenolith of the deep mantle found in the Premier kimberlite of
South Africa.

Fig. 1. Sharp-edged octahedral diamond
protruding from a coarsely crystalline dunite
xenolith sample from the Udachnaya kimberlite,
Siberia. Such xenoliths are thought to be the
dominant host rocks for diamonds in the
Udachnaya kimberlite pipe. The presence of
diamond indicates derivation from great depth
(at least 140 km), and Re-Os isotope
systematics in this type of xenolith indicate an
Archean age, greater than 2.5 billion years.

keel point to some non-plate-tectonic mechanism for the origin of the
first continental crust?

Addressing these questions, using chemical and isotopic tracers to
reconstruct the geologic history of the mantle keels and their influence
on the volcanism that has penetrated continents, has been a prime goal
in the geochemical research at DTM.

Direct Examination: Mantle Samples in the Laboratory

Certain types of continental volcanism, particularly the kimberlite
type, originate from sufficient depth and erupt with such explosive
force that they carry to the surface pieces of the mantle that line the
volcanic conduits. These "xenoliths" of mantle material, including
diamonds and their silicate mineral inclusions (Fig. 1), provide samples
of continental mantle from depths of up to 200 km and perhaps much
deeper. In many previous studies over the years, Boyd and colleagues
have shown that most mantle xenoliths from old continental keels have
major-element characteristics suggesting that they are residues from the
extraction of partial melts. Melting in the mantle preferentially extracts
elements like calcium, aluminum, and iron, to leave a residue enriched
in magnesium (Fig. 2). The depletion in aluminum lessens the
abundance of the dense mineral garnet in the depleted mantle which,
coupled with its relatively low iron content, causes depleted
subcontinental mantle to be less dense than surrounding "fertile"
mantle even after it cools below ambient mantle temperatures. Thus,
the thick sections of seismically slow mantle beneath old continents
float stably because of their intrinsically low density caused by partial
melt removal.

To better understand the mechanism of formation of continental
mantle keels, we have been working with Peter Nixon of Leeds
University on xenoliths from southern Africa and with visiting
scientists Nicholai Sobolev and Nicholai Poikilenko on a similar
xenolith suite from Siberia. Through study of the trace-element and
isotopic compositions of the xenoliths, we have been able to reconstruct

112

CARNEGIE INSTITUTION

much of the geologic history of the continental mantle keels and infer
the mechanism of their origin and their role in continent formation and
stabilization.

Time and Duration of Keel Formation

The first question to be addressed is how old are these continental
keels? Age determinations can provide answers to several questions.
Did the keels form by gradual cooling from above? Are they created in
some event of much shorter duration? What is the relation of their age
to the age of the overlying continental crust?

The most common method to determine the age of a rock relies on
the gradual build-up of the decay products of naturally occurring
radioactive elements in individual minerals. Mantle xenoliths, however,
resided at temperatures of 800°C or higher in the mantle prior to their
capture by the volcanic host. At such high temperatures, chemical
diffusion is sufficiently fast to homogenize the isotopic composition of
the generally sub-millimeter-sized minerals that form these rocks.
Because of this, ages determined by comparison of the isotopic
composition of separated minerals from a single xenolith usually reflect
the time of eruption of the host magma, but not necessarily the time of

65

60
O

0> 55

50

% Melt Removed from Mantle

30%

+ Kaapvaal
o Siberian

(Q Fertile, Unmelted Mantle

1.0

2.0

3.0

4.0

5.0

6.0

Fig. 2. Partial melting of primordial, "fertile" material in the mantle leaves residues
enriched in magnesium and depleted in iron. Here, the circle at lower right
represents fertile mantle. The solid lines show experimentally determined values of
FeO vs. MgO concentration in residues following various degrees (percentages) of
melting at conditions generally understood to exist in the mantle.

Crosses and circles plot FeO vs. MgO concentrations measured in mantle
xenoliths from the Kaapvaal and Siberian cratons. It can be seen that if a simple
melting model for craton formation is applicable, then these xenoliths could be
residues of between 20% and 50% melting of fertile mantle.

TERRESTRIAL MAGNETISM 113

formation of the section of mantle from which the xenolith was derived.

Formation ages for the mantle keel theoretically could be
determined by comparison of the radiogenic isotopic composition of
different xenoliths sampled from nearby localities. However, the
xenolith sampling process is random, and there is no guarantee that
different xenoliths are related. In addition, the xenoliths often are
contaminated by small amounts of infiltration from the host magma.
Compared to the xenoliths, the host magmas contain very high
concentrations of strontium, neodymium, and lead. Contamination by
the host magma thus severely perturbs the indigenous isotopic
composition of these radiogenic elements in the xenoliths, eliminating
the possibility of age determination by these classical radiometric
systems.

What was needed in order to determine the age distribution of the
subcontinental mantle was a technique that could provide the age of a
single xenolith. That technique was afforded by technical developments
that allowed measurement of the rhenium (Re) and osmium (Os)
isotopic composition of xenolith samples (see essay by Shirey and
Carlson, Year Book 90, pp. 58-71). During the event that depleted the
mantle xenoliths in calcium, aluminum, and iron, Re also appears to
have been nearly completely removed, while Os concentrations either
were unaffected or increased slightly. This is exactly what would be
expected given the chemical behavior of Re and Os during melting at
mantle conditions. Re is a so-called incompatible element, which means
that it preferentially partitions into the melt in melt formation. Os, on
the other hand, is a strongly compatible element; it concentrates in the
residual minerals rather than going into the forming melt. Thus, the
depletion of Re in subcontinental mantle xenoliths is consistent with
the major-element characteristics described earlier suggesting that
xenoliths (and the keels they represent) are the residues of some past
partial melt extraction.

The radioactive isotope 187Re decays into 187Os with a half-life of
42.5 billion years. Thus the Os composition of a sample containing 187Re
is constantly changing. But the extraction of Re from the subcontinental
mantle "freezes in" the Os isotopic composition of the future xenolith
samples at the time of the event responsible for Re loss. By comparison
with the Os isotopic compositions expected for fertile mantle (mantle
not depleted by melting) throughout the Earth's history, the measured
Os isotopic composition of a mantle xenolith can be used to determine
the time of the Re depletion event. These "Re-depletion" ages are
minimum estimates of the true age of differentiation, since both
incomplete Re extraction in the initial event and Re addition by
possible later magma infiltration will result in continued Os isotopic
evolution and hence younger estimates of the time of Re depletion (Fig.
3).

10% Melt

Residue of 30% Melting

4.0

3.0

2.0

1.0

Present

Time (billion years ago)

Fig. 3. The ratio of 1870s to 1880s changes with time as the result of 187Re decay
into 1870s. In the fertile mantle, the isotopic composition of Os will evolve over the
Earth's history along the dark line. Here, a melting event occurring 3.5 billion years
ago is postulated; the preferential extraction of Re into the melt would produce rapid
growth in 1870s in the extracted material (shown in the near-vertical lines), but less
change in 1870s in the residue material (shown in the more-horizontal lines).

Present-day measurement of 1870s/1880s (= 0.12 here) in the residue gives an
indication of the age of Re depletion TRD by extrapolating horizontally (dashed line) to
intersect the dark line. As shown here, if the extent of partial melting is low (here
1 0%) the result will underestimate the true age of the melting event, while if the
extent of melting is greater (30%), the Re/Os of the residue will approach zero and
the TRD will approach the true age (here 3.5 billion years) of melting.

Figure 4 shows the results of our Os isotopic measurements of
xenoliths from southern Africa. The ages determined for individual
samples are plotted at the approximate depth of origin as determined
by major-element chemical partitioning between the minerals of the
xenoliths. Looking, for example, at the data for xenoliths from the
kimberlites from North Lesotho, a sample from approximately 50 km
depth gives a Re-depletion model of 2.9 billion years, while a much
deeper sample, one derived from within the stability field of diamond,
gives a nearly identical age of 2.8 billion years. Similar ages have been
obtained for xenoliths from throughout the depth range sampled by
xenoliths from the Siberian craton mantle. Even ignoring the fact that
Re-depletion model ages are minimum estimates to the formation age
of these samples, every xenolith analyzed so far from the nearly
200-km-thick section sampled by the North Lesotho kimberlites
suggests an ancient origin (i.e., 2.6 billion years ago or more) for the
material that makes up the mantle keel. Furthermore, the implied
formation interval of only a few hundred million years or less for the
whole, 200-km-thick, mantle keel is too short to be consistent with
formation by cooling from above and suggests another mechanism of
formation. Scatter in Re-depletion ages observed in South African and
Siberian pipes may reflect true scatter in formation ages for the
subcontinental mantle, but it may reflect nothing more than imperfect

TERRESTRIAL MAGNETISM

115

adherence of the samples to the simple single-event depletion model
used in the calculation of their Re-depletion ages.

The maximum ages obtained for samples of the mantle keels in the
Siberian and Kaapvaal cratons are essentially the same as the oldest
ages obtained for rocks in the overlying crust. This result suggests that
substantial portions of the thick mantle keels beneath the continents
formed at the same time as the overlying crustal sections, and that they
have remained firmly attached to the crust ever since (Fig. 5). The
long-term stable association of crust with mantle keel is particularly
surprising, since although mantle keels are indeed cooler than the
ambient convecting mantle below, temperatures are still high enough
(1000°C) to allow the keels to deform plastically and eventually to flow
and mix with surrounding convecting mantle.

Formation Mechanism of Mantle Keels

The evidence for depletion in Re and the major elements that
partition into melts suggests that continental mantle keels are residues
left from melt extraction. The degree of melt extraction needed to
explain the major-element composition of keel rocks, however, is very
large compared to that observed in the residues of modern mid-ocean
ridge melting, which produces melts of basaltic composition. The
ancient Re-Os ages obtained for xenoliths from the mantle keels
indicate that the melting events occurred early in the Earth's history,
when the average temperature of the mantle was hotter than it is today.

W I

1

I

|

Crust

2.2-

spinel

2.7-

2.9-
3.3-

garnet

2.6-

2.3-
2.2-

2.6-

1.7-

graphite
diamond

_ 3.1-

...

2.1 -

3.3-

2.8-

Fig. 4. Schematic cross-section of the
mantle provided by three kimberlite
localities (Jagersfontein, Premier, and
North Lesotho — the solid vertical pipes)
erupted through the Kaapvaal craton of
southern Africa. Numbers along these
pipes show the Re-depletion model
ages, in billions of years, obtained from
xenoliths derived from the approximate
depths shown. The spinel-garnet and
graphite-diamond lines show the depth
of important phase changes in the
mantle caused by increasing pressure
with depth; these are guideposts in the
determinations of depth indicated.

Kaapvaal Craton

O CO

>- CD

It

10

Lower crustal xenoliths I 1

Witwatersrand Osmiridiums I 1

Greenstones & Ancient Gneiss Complex I — I

_

>

1

0.5

1.5

2.5

3.5

Fig. 5. Histogram shows Re-depletion
model ages TRD obtained from Kaapvaal
and Siberian craton xenolith samples.
Note that TRD's are minimum age
estimates so that a histogram peak at 2.2
billion years for the Kaapvaal and 1 .8
billion years for Siberia is not inconsistent
with the craton formation ages of 3-3.5
billion years. Also shown, in the
horizontal bars, are measured ages of
the oldest surface rocks overlying both
cratons, plotted against the scale at foot.
These values define the 3-3.5 billion
year continental age.

Siberian Craton

Anabar Shield

Olekma Gneiss-Greenstones Aldan Shield

Eclogite xenoliths

10

owe
i_ CD O

£ Q.
-P CO 2

Eruption Age

0.5

1.5

2.5

3.5

TRD (billions of years)

Nevertheless, the predominant volcanic rock erupted in the Archean
(2.5 billion years ago) is basalt not significantly different in composition
from modern basalts. This indicates that the shallow Archean mantle
probably was not more than about 200°C hotter than the present
shallow mantle.

One means to bring hotter, deep mantle towards the surface is as a
"plume" of rising material. Plumes are cylindrical "bubbles" that rise
through the general circulation pattern of mantle convection to create
fixed centers of volcanism, such as at Hawaii today. Plumes are thought
to be initiated at major thermal boundary layers in the Earth's interior,
for example the core-mantle boundary, where the high temperature of
the lower layer causes material of the upper layer to form plumes
which carry off the heat from below.

Given the very highly melt-depleted character of the mantle keels
to Archean cratons (such as the Kaapvaal and Siberian), the materials
that make up these keels may be the residues of ancient plumes left
behind after the extraction of high-degree (more than 30%) partial
melts. High-degree melts, called komatiites, are known in Archean
surface areas, but they are rare and volumetrically inconsequential
compared to the volume of melt that would be produced by
high-degree melting to leave a complete mantle keel. An alternate
explanation for the fate of the high-degree melts is as follows: as the
unmelted source plume rose from the deep mantle, melting occurred at
a depth great enough for the melts to sink rather than rise with the
residual solids. (Because silicate melts are more compressible than solid
crystals, at approximately 200-km depth melts are more dense than the

TERRESTRIAL MAGNETISM 117

solids they form from. Under these conditions, the residual solids will
continue to rise as the plume, but the melts will descend and remain in
the deeper mantle.) Thus, the combination of ancient ages, a small
spread in age, and the highly melt-depleted character of mantle keels
suggest that the first cores to the continents formed not in a subduction
setting, as modern continental crust seems to form, but by large-degree
melting of a hot plume rising from the deep mantle.

The Tectonic Evolution of Venus

by Sean C. Solomon

The planet Venus provides a strong challenge to the maxim that the
study of other planetary bodies will lead to a deeper
understanding of the Earth. Venus is the planet most similar to the
Earth in mass, radius, and solar distance. Current theories for the early
evolution of the inner solar system — in the development of which
DTM's George Wetherill has played a leading role — suggest that Earth
and Venus formed by the accretion of planetesimals which collectively
constituted a well-mixed sample of material from the inner solar
nebula. Thus the bulk compositions of the two planets should be
similar, and, in particular, the rates of internal heat generation and
therefore the energy available to drive interior convection should also
be similar. An important difference between the two planets, however,
is in the character of their atmospheres. The mass of the dominantly
C02 atmosphere of Venus is two orders of magnitude greater, as a
fraction of planet mass, than that of the Earth, and the surface
temperature is 450°C higher, a consequence of continuous global cloud
cover and a runaway greenhouse. The column density of H20 in the
Venus atmosphere is from four to five orders of magnitude less than
that of the atmosphere and hydrosphere on Earth. As a result, the
Venus surface lacks a water cycle, and the processes of weathering,
erosion, and sediment transport that dominate terrestrial landforms are
comparatively unimportant.

On Earth, the surface manifestation of interior convection is the
steady relative motion of the tectonic plates, which separate at
mid-ocean ridges, converge at deep-sea trenches and active mountain
belts, and slip horizontally past one another along great fault zones.
The recycling of oceanic plates at convergence zones, and their
magmatic renewal at mid-ocean ridges, serve to resurface the Earth's
ocean floor continuously on a time scale of about 100 million years. The
Earth's continents, underlain by thick buoyant crust, do not participate

118 CARNEGIE INSTITUTION

significantly in that recycling and thus preserve a long and complex
history of deformation, igneous activity, erosion, and sedimentation, as
well as rocks as old as four billion years. To what extent do the
large-scale patterns of volcanism and deformation on Venus, with a
similar internal heat budget but with very different surface conditions,
resemble those of the Earth?

This question was among several that motivated the Magellan
spacecraft mission to Venus. While the thick cloud cover precludes
optical studies of the Venus surface from Earth or from orbit, a series of
Earth-based and orbital radar experiments dating back three decades
demonstrated that radar imaging could yield important information on
the planet's geology. The Magellan mission, managed by the Jet
Propulsion Laboratory, was designed to image the surface at a
horizontal resolution of 100-300 m and to map the surface elevation at
a vertical resolution of about 80 m and a horizontal resolution of about
10 km. A single radar system, operated in a side-looking synthetic
aperture mode for imaging and in a nadir-looking mode for altimetry,
accomplished both objectives. As a member of the Magellan radar
team, I was charged with leading the team efforts to apply the mission
results to an understanding of the global tectonics of Venus.

The mission lasted more than five years. The spacecraft was
launched in May 1989 and placed into a nearly polar, elliptical orbit
about Venus in August 1990. Over the course of each Venus day (equal
to 243 Earth days), Venus turned once on its axis beneath the plane of
the spacecraft orbit. For two years, Magellan obtained radar images of
more than 98% of the Venus surface. In the fall of 1992 the elevation of
the spacecraft orbit at closest approach (periapsis) was lowered to 180
km, and the transmitter antenna was pointed toward the Earth during
periapsis passage to permit the measurement of spacecraft
accelerations (inferred from Doppler shifts in the transmitter carrier
frequency) produced by the planetary gravitational field. Because the
sensitivity to the gravity field of a spacecraft in an elliptical orbit is
poor at latitudes far from the periapsis latitude, an aerobraking scheme
was carried out during the summer of 1993 to achieve a nearly circular
orbit of about 200-300 km elevation. Tracking the spacecraft in this
circular orbit until October 1994 yielded a global gravity field of nearly
uniform resolution.

Volcanism and Tectonics

Magellan images revealed that volcanic and tectonic features of a
wide variety of styles and scales are present on Venus. Volcanic plains
constitute 80% of the surface. Edifices range in size from small domes
near the limit of resolution to large volcanoes hundreds of kilometers in
diameter. Most of the plains have been subjected to modest

Fig. 1 . Magellan radar image of the rifted highland region known as Beta Regio.
The radar-bright areas consist of a fabric of closely spaced families of faults and
folds of various trends. This terrain has been stretched in the east-west direction,
leading to the formation of north-south-trending faults and the steep-sided rift valley
(with east-facing walls nearly in radar shadow) visible in the center of the image. The
rift-related faults splay to the northwest and northeast. Dark patches are smooth and
are inferred to be volcanic deposits overlying the older bright terrain. The image is
centered at about 33.5°N, 283°E, and is 900 km wide. (This and all subsequent radar
images are in sinusoidal equal-area projection; north is up, and the radar illumination
direction is from the left; the incidence angle of the radar is about 41 ° for this image
and in general is a function of latitude.)

deformation, typically manifested as families of faults or folds spaced
at a few to a few tens of kilometers and often coherent over distances of
hundreds or thousands of km. Zones of more-concentrated horizontal
extension or shortening of the crust are also common. There are rift
zones (Fig. 1) having dimensions and relief similar to intracontinental
rift structures on Earth, such as the East African or Rio Grande rifts.
Ridge belts (Fig. 2), marked by many closely spaced folds and thrust
faults and up to 1 km of relief, are the dominant structures in several
plains regions. Ringing one highland region are mountain belts (Fig. 3)
comparable in relief and horizontal dimensions to those on Earth; these
belts presumably formed, as on Earth, by horizontal compression and
crustal thickening. Few large-offset strike-slip faults, such as the San
Andreas fault on Earth, are observed on Venus, but limited local
horizontal shear has been accommodated across many zones of crustal
stretching or shortening (Fig. 2).

Venus also displays landforms having no evident terrestrial
counterpart. Many elevated areas are characterized by extremely
complex, intersecting patterns of tectonic features at a range of scales
(Fig. 4). These tessera terrains preserve a record of multiple stages of
pervasive strain of diverse geometry. Apparently unique to Venus are

120

CARNEGIE INSTITUTION

the generally circular corona structures, 60 to more than 1000 km in
diameter, typically marked by an annulus of closely spaced, concentric
faults and folds (Fig. 5). Many coronae have elevated interiors, and
many are centers of extensive volcanism. The leading interpretation is
that these features overlie sites of upwelling and melt generation in the
Venus mantle.

In general, the preserved record of global volcanism and tectonics
of Venus does not resemble plate tectonics on Earth. Venus has no
globally continuous system of structures analogous to the Earth's
tectonic plate boundaries, and no landforms analogous to terrestrial
mid-ocean ridges. How, then, can we begin to make sense of the
diversity and distribution of volcanic and deformational features on the
planet?

Age of the Venus Surface

A critical context for
interpreting a planet's
geological record is
information on the age of
the surface. For Venus, in
the absence of returned
rock samples suitable for
geochemical analysis, the
only measure of surface
age is the density of
impact craters. As
expected on the basis of
earlier data and theoretical
models, Magellan revealed
that impact craters smaller
than about 30 km in
diameter are
underrepresented on
Venus (because of the
severe decrease in the
kinetic energy of small
meteoroids during transit
through the dense Venus
atmosphere). The spatial
density of craters larger
than 30 km in diameter,
together with estimates of
the cratering rate scaled
from the Earth and Moon

-;S»lllwf««sil«ii

II

m.

1811

mm

Fig. 2. Magellan radar image of a ridge belt in the
lowland plains region known as Lavinia Planitia. The
ridge belt, visible as the family of bright, NNE-trending
ridges on the left side of the image, rises 200 m above
the surrounding plains. Individual ridges are 1-5 km
wide and spaced 5-15 km apart. Long, narrow
lineations trend primarily WNW. Some of these
lineations curve as they approach, and appear to be
offset horizontally across, the ridge belt. The
combination of positive relief and horizontal offset
suggests that the ridge belt was formed by a
combination of compression and left-lateral shear. The
image, centered near 49°S, 343°E, is 240 km wide.

Fig. 3. Magellan radar image of part of the
northwestern arm of Maxwell Montes, which
stand at elevations up to 11 km above mean
planetary elevation and constitute the highest
mountain belt on Venus. Elevation rises 5 km
from the northwest corner to the eastern edge of
the image. The radar-bright front of the mountain
belt, sloping approximately SW in the region
shown, consists of ridges spaced 3-10 km at
lower elevations (lower center of the image) and
10-20 km at the higher elevations to the right.
Steeper slopes on the western sides of these
ridges suggests that they are the product of
thrust faulting. On the steep slope of the
mountain belt visible in the northwestern corner
of the image are depressions 1-2 m wide and
spaced 15 km apart; these extensional
structures are likely the result of gravitational
spreading of the high terrain. The image,
centered near 66.5°N, 357°E, is 250 km wide.

or taken from the known
population of Venus-crossing
asteroids, indicate an average
surface age of about 500 million
years, or 10% of the age of the
solar system. This surface age,
greater than that of the Earth's
ocean floor but less than the
radiometric age of the Earth's
continental rocks or the surface
age of the Moon, Mercury, or
Mars, in itself is not remarkable
for a planet having a hot,

Hilt
iii'ii

-tfMH

IIIP

lliill

fill

asaiiii|||||||

SifiMiiiliM

III

: I

wm%m

wmimmigKmmmBimm

mmmmmmbMmm^mmmMmmwmiim

Fig. 4. Magellan radar image of heavily deformed tessera
terrain in the upland area known as Tellus Regio. The terrain is
dominated by extensional fault structures trending NNW. Several
NE-trending topographic ridges may be remnants of earlier
products of horizontal shortening. This type of complexly
deformed terrain is typical of many highland regions on Venus.
The image, 120 km wide, is centered on 39.5°N, 85.7°E.

122

dynamic interior (like the
Earth), albeit one on which
erosion is unimportant.

On most solid planets
and satellites, the density of
impact craters varies from
one geological unit to
another, and there are
abundant examples of craters
substantially modified by the
later action of internal (e.g.,
volcanism, faulting) or
surface processes. On Venus,
in contrast, the global
distribution of craters is
indistinguishable from that of
a spatially random
population, and most of the
craters (Fig. 6) have not been
significantly modified by
tectonic deformation or by
volcanic flows external to the
crater rim. One interpretation
of these unusual
characteristics is that most of
the surface of Venus dates
from the end of a global

resurfacing event that ceased abruptly about 500 million years ago,
and that the small fraction of craters volcanically embayed or modified
by deformation indicates that volcanic and tectonic activity since that
time has been at much lower levels. A contrasting view is that the
Venus surface exhibits a spectrum of ages. This view is supported by
the observations that modified craters tend to be located in areas of low
crater density (i.e., we are seeing the crater removal process at work)
and that low crater density appears to correlate with increased radar
backscatter (a quantity elevated in regions of high topography and high
roughness, both thought to be signatures of comparative geological
youth).

While the paucity of small craters prevents the use of crater density
to determine the relative ages of individual geological units,
as has been done for the solid planets and satellites lacking a significant
atmosphere, it is possible to group areas on Venus by criteria
independent of the crater population and to assess relative ages among
groups. On this basis, MIT predoctoral fellow Noriyuki Namiki and I
were able to show that the density of impact craters on 175 volcanoes at

Fig. 5. Magellan radar image of the Idem-Kuva corona
structure. Corona structures are distinguished by an
annulus of deformed terrain and frequently by an elevated
interior. Radar-bright volcanic flows emanate from
topographic highs of more than 1 km relief in the eastern
and western portions of this structure. The corona,
centered at 25°N, 358°E, is about 230 km in diameter.

TERRESTRIAL MAGNETISM

123

least 50 km in diameter, as a group, is half that of the planet as a whole.
In other words, the lava flows that make up the surfaces of these large
volcanoes should have an average age of approximately 250 million
years. Of course, flows both younger and older than this age must be
present, and a plausible hypothesis is that the age distribution of large
volcanoes is approximately uniform over the last 500 million years. By
similar reasoning, we have shown that while coronae as a group are not
significantly younger than the global average surface age, the
subgroups of coronae having the most voluminous volcanic deposits
are resolvably younger. Another team has used the same approach to
argue that tessera terrain has a greater density of large impact craters
and is therefore older than the average planet surface and, in particular,
the widespread volcanic plains. Careful stratigraphic mapping by
planetary geologists has verified that tessera terrain is older than, and
volcanoes are typically younger than, both regional plains deposits and
most corona structures.

Gravity Anomalies

Important clues to the interior structure and dynamics of Venus
come from an examination of the relationship between variations in the
gravity field and variations in surface elevation. Variations in gravity

Mffl

Fig. 6. Magellan radar image of an impact crater 70 km in diameter. Radar-bright,
rough-textured ejecta extending up to two crater radii from the crater center (near
4°S, 157°E) and the remarkable bright flow features extending hundreds of
kilometers from the crater walls are thought to date from the impact event and have
not been subsequently modified to any significant degree by later deformation or
volcanism exterior to the crater (although the generally radar-dark, smooth floor of
the crater may contain volcanic deposits of younger age).

124 CARNEGIE INSTITUTION

(often expressed as variations in the height of the gravitational
potential surface, or geoid, from that expected for a rotating fluid body
of radially varying density) are produced by both the gravitational
attraction of topography and the internal density structure of the
planet. It has been known since the first spacecraft were placed in orbit
around Venus that, in contrast to the situation on Earth, topography
and gravity on Venus are strongly correlated at scales of thousands of
kilometers. The gravity measurements obtained by Magellan have
improved the definition of the field and, in particular, have extended
the determination of the field globally to scales as short as 500 km.

MIT predoctoral fellow Mark Simons and I, together with Bradford
Hager of MIT, have been exploring the relationship between gravity
anomalies and topography on Venus by mapping variations in the
admittance, the ratio of geoid height to topography. The strong
variation of admittance with scale for the planet as a whole and for
several broad highland rises characterized by rift zones and large
volcanoes is in general agreement with admittances predicted by
numerical models of interior dynamics where a high-viscosity
lithosphere overlies a convecting mantle and normal tractions on the
base of the lithosphere give rise to topographic variations at horizontal
scales of hundreds to thousands of km. The admittance values for
highland plateaus dominated by tessera terrain, in contrast, indicate
that topography is compensated by density variations at shallow (25-50
km) depths and are consistent with the view that such regions consist
of elevated blocks of thicker-than-average crust that are no longer
associated with areas of vigorous upwelling or downwelling of the
underlying mantle.

The shortest-scale components of the gravity field provide
information on the mechanical properties of the Venus lithosphere.
Together with Simons, MIT predoctoral fellow Patrick McGovern, and
James Head of Brown University, I have focused on the gravity
anomalies over large volcanoes on Venus. The motivation for this work
is that the flexure of a planetary lithosphere in response to loading by a
large volcano is a well-understood mechanical problem, and the
comparatively young ages of large volcanoes give us an opportunity to
investigate the nature of the lithosphere during the most recent era of
Venus history. The gravity anomalies over eight large volcanoes on
Venus, each modeled as a vertical load on an elastic plate, yield
best-fitting elastic thicknesses of 30-70 km.

Such lithosphere thicknesses are comparable to those in oceanic
regions on Earth. At face value this result is surprising because the base
of the lithosphere on either planet is governed by the temperature at
which rocks flow at geologically significant rates. Because the surface
temperature on Venus is 450°C greater then on Earth, the similar
thicknesses for the elastic lithosphere imply either that the rate of heat

TERRESTRIAL MAGNETISM 125

flow on Venus is less than on Earth or that geologically significant flow
rates begin at a much higher temperature in the anhydrous crust or
upper mantle of Venus than in the Earth's upper mantle. The former
explanation is presently favored, but considerable work now in
progress must be completed before this conclusion may be regarded as
firm. First, we are carrying out modeling calculations of alternative
mechanisms for support of volcano topography, including crustal
thickness variations, depletion of the lithospheric mantle following
melt extraction, and mantle convective tractions. Second, we are
quantifying the estimates of thermal gradient implied by a given elastic
lithosphere thickness on Venus, including the uncertainties associated
with both the thickness estimate and the temperature dependence of
rock strength. Finally, we are exploring mechanisms by which the
mantle of Venus might be losing less heat (per unit mass) than the
mantle of Earth, including a lesser heat production, a greater
fractionation of heat production into the crust, and a strongly
time-variable mantle heat flux.

Implications for Resurfacing

Did Venus undergo a catastrophic resurfacing 500 million years
ago, and, if so, what was the nature of global tectonics and volcanism
both during and after that catastrophe? Some sort of catastrophic
resurfacing is strongly implied by the small fraction of impact craters
modified by exterior volcanism or significant deformation in the last
500 million years. The nature of the resurfacing event is not known, but
global-scale foundering of the lithosphere and a strong pulse of
mantle-delivered heat have been two suggestions. The presence of
terrains of such pervasive and complex deformation that they could not
have formed during the present era of a strong Venus lithosphere is
consistent with this view, but it is nonetheless noteworthy that
differences in surface ages on Venus can be resolved.

A working hypothesis consistent with the observations is that for
an unknown time interval prior to 500 million years ago, the heat flux
on Venus was greater than at present and the lithosphere was weak and
readily deformable in response to mantle convective tractions. Impact
craters and volcanic flows during that era would have been rendered
unrecognizable by deformation. The tessera terrain date from the end
of that era. About 500 million years ago, the lithosphere strengthened
and stabilized, but melting in a still-hot upper mantle gave rise to the
formation of the volcanic plains and most coronae. Continued
strengthening of the lithosphere led to the most recent era of tectonics
and volcanism, marked by a few zones of limited rifting and volcanism
localized to a small number of large constructs. Will Venus be subjected
to another catastrophic resurfacing event in the future? An affirmative

126

CARNEGIE INSTITUTION

answer will be favored if the present rate of global heat loss is
confirmed to be less than the rate of interior heat production.

While this working hypothesis is sure to require revision as further
analysis of Magellan mission results is completed, it is already clear
that the inner workings of Venus manifest themselves at the surface in a
fashion very different from that on Earth. While Venus presently lacks
global plate tectonics, it has been subjected to a unique resurfacing
history, one which challenges our ability to interpret and explain.
Further study of Magellan images, refinement of the global gravity
field, and continued development of interior dynamical models should
sharpen the competing hypotheses. The long-term goal, yet beyond
reach but still worthy of pursuit, is an improved general understanding
of mantle convection and melting on all the terrestrial planets,
including Earth.

Bibliography

Reprints of the numbered publications
listed below can be obtained, except where
noted, at no charge from the Librarian,
Department of Terrestrial Magnetism, 5241
Broad Branch Road, N.W., Washington, D.C.
20015. When ordering, please give reprint
number(s).

5233 Aldrich, L. T., Isotope geology at Carnegie
1950-1970: dating Earth processes, in The
Earth, the Heavens, and the Carnegie Institu-
tion of Washington, G. A. Good, ed., pp.
215-224, American Geophysical Union,
Washington, D.C, 1994.

5274 Barash, T. W., C. G. Doll, Jr., J. A. Collins,
G. H. Sutton, and S. C. Solomon, Quantita-
tive evaluation of a passively leveled
ocean bottom seismometer, Mar. Geophys.
Res. 16, 347-363, 1994.

5265 Bina, C. R., and G. Helffrich, Phase tran-
sition Clapeyron slopes and transition
zone seismic discontinuity topography, /.
Geophys. Res. 99, 15853-15860, 1994.

5270 Bjarnason, I. T., W. Menke, and 6. G.
Flovenz, Reply [to comment by 6. Gud-
mundsson on "Tomographic image of the
Mid-Atlantic plate boundary in south-
western Iceland"], /. Geophys. Res. 99,
17915-17917, 1994.

5246 Boss, A. R, Origin of binary stars, in
Reports on Astronomy, Transactions of the

International Astronomical Union, Vol. 22A,
J. Bergeron, ed., pp. 481-483, Kluwer
Academic Publishers, Dordrecht, 1994.

5247 Boss, A. P., Tidal disruption of Periodic
Comet Shoemaker-Levy 9 and a con-
straint on its mean density, Icarus 107, 422-
426, 1994.

Boss, A. P., Capture mechanisms, in En-
cyclopedia of Planetary Sciences, J. H. Shirley
and R. W. Fairbridge, eds., Van Nostrand
Reinhold, New York, in press.

Boss, A. P., Collapse and fragmentation

of molecular cloud cores. II. Collapse in-
duced by stellar shock waves, Astrophys.
/., in press.

Boss, A. P., Earth-Moon system: origins,

in Encyclopedia of Planetary Sciences, J. H.
Shirley and R. W. Fairbridge, eds., Van
Nostrand Reinhold, New York, in press.

Boss, A. P., Proximity of Jupiter-like

planets to low mass stars, Science, in
press.

5226 Boss, A. P., and J. A. Graham, Clumpy
disk accretion and chondrule formation,
Icarus 106, 168-178, 1993.

Boss, A. P., and E. A. Myhill, Second-
order-accurate radiative hydrodynamics
and multidimensional protostellar col-
lapse, Comput. Phys. Commun., in press.

5268 Bostock, M. G., and J. C. VanDecar, The
influence of crust and upper-mantle
heterogeneity on short-period waveform

TERRESTRIAL MAGNETISM

127

distortion, Phys. Earth Planet. Inter. 83,
225-247, 1994.

5240 Brown, L., An annotated bibliography of
radar history, in Tracking the History of
Radar, O. Blumtritt, H. Petzold, and W.
Aspray, eds., pp. 323-361, IEEE-Rutgers
Center for the History of Electrical En-
gineering and the Deutsches Museum,
Piscataway, N.J., 1994.

5241 Brown, L., Significant effects of radar on
the Second World War, in Tracking the His-
tory of Radar, O. Blumtritt, H. Petzold, and
W. Aspray, eds., pp. 121-135, IEEE-Rut-
gers Center for the History of Electrical
Engineering and the Deutsches Museum,
Piscataway, N.J., 1994.

Brown, L., Accelerator mass spectro-
metry, in Modern Analytical Geochemistry,
R. Gill, ed., Ch. 12, Longman Higher Edu-
cation Publishers, Harlow, Essex, U.K., in
press.

5238 Brown, P., Z. Ceplecha, R. L. Hawkes, G.
Wetherill, M. Beech, and K. Mossman, The
orbit and atmospheric trajectory of the
Peekskill meteorite from video records,
Nature 367, 624-626, 1994.

5287 Butner, H. M., Multi-wavelength spatial
observations of dust emission: merits and
limits, in Clouds, Cores, and Low Mass Stars,
D. P. Clemens and R. Barvainis, eds., pp.
251-255, Conference Series, Vol. 65,
Astronomical Society of the Pacific, San
Francisco, 1994.

5286 Butner, H. M., J. Di Francesco, N. J. Evans
II, P. M. Harvey, L. G. Mundy, and A.
Natta, Density profiles of the envelopes
surrounding Herbig Ae/Be stars, in The
Nature and Evolutionary Status of Herbig
Ae/Be Stars, P. S. The, M. R. Perez, and E.
P. J. van den Heuvel, eds., pp. 185-188,
Conference Series, Vol. 62, Astronomical
Society of the Pacific, San Francisco, 1994.

Butner, H. M., E. A. Lada, and R. B.

Loren, Physical properties of dense cores:
DCO+ observations, Astrophys. J., in press.

Butner, H. M., and A. Natta, Lick Ha 198

revisited, Astrophys. /., in press.

5281 Carlson, R. W., Isotopic inferences on the
chemical structure of the upper mantle, in
Invited Lectures, International Symposium on
the Physics and Chemistry of the Upper
Mantle, August 14-19, 1994, Sao Paulo,
Brazil, pp. 99-116, CPRM and FAPESP,
Brazil, 1994. (No reprints available.)

5290 Carlson, R. W., Mechanisms of Earth dif-
ferentiation: consequences for the chemi-
cal structure of the mantle, Rev. Geophys.
32,337-361,1994.

5276 Carlson, R. W., and A. J. Irving, Deple-
tion and enrichment history of subcon-

tinental lithospheric mantle: an Os, Sr, Nd,
and Pb isotopic study of ultramafic
xenoliths from the northwestern Wyom-
ing Craton, Earth Planet. Sci. Lett. 126, 457-
472, 1994.

5249 Castillo, P. R, M. S. Pringle, and R. W.
Carlson, East Mariana Basin tholeiites:
Cretaceous intraplate basalts or rift basalts
related to the Ontong Java plume?, Earth
Planet. Sci. Lett. 123, 139-154, 1994.

5285 Di Francesco, J., N. J. Evans II, P. M.
Harvey, L. G. Mundy, and H. M. Butner,
100 micron observations of Group I Her-
big Ae/Be stars, in The Nature and Evolu-
tionary Status of Herbig Ae/Be Stars, P. S.
The, M. R. Perez, and E. P. J. van den
Heuvel, eds., pp. 181-184, Conference
Series, Vol. 62. Astronomical Society of the
Pacific, San Francisco, 1994.

5284 Di Francesco, J., N. J. Evans II, P. M.
Harvey, L. G. Mundy, and H. M. Butner,
Constraining circumstellar environments:
far-infrared observations of Herbig Ae/Be
stars, Astrophys. J. 432, 710-719, 1994.

Edwards, C. M. H., M. A. Menzies, M. F.

Thirlwall, J. D. Morris, W. P. Leeman, and
R. S. Harmon, The transition from calc-
alkaline to potassic alkaline volcanism in
island arcs: the Ringgit-Beser Complex,
East Java, Indonesia, /. Petrol., in press.

5288 Foster, P., A guide to isothermal gravita-
tional collapse, in Clouds, Cores, and Low
Mass Stars, D. P. Clemens and R. Barvainis,
eds., pp. 105-114, Conference Series, Vol.
65, Astronomical Society of the Pacific,
San Francisco, 1994.

5256 Freedman, W. L., S. M. Hughes, B. F.
Madore, J. R. Mould, M. G. Lee, P. Stetson,
R. C. Kennicutt, A. Turner, L. Ferrarese, H.
Ford, J. A. Graham, R. Hill, J. G. Hoessel,
J. Huchra, and G. D. Illingworth, The Hub-
ble Space Telescope extragalactic distance
scale key project. I. The discovery of
Cepheids and a new distance to M81,
Astrophys. J. 427, 628-655, 1994. (No
reprints available.)

5278 Freedman, W. L., B. F Madore, J. R.
Mould, R. Hill, L. Ferrarese, R. C. Ken-
nicutt, Jr., A. Saha, P. B. Stetson, J. A.
Graham, H. Ford, J. G. Hoessel, J. Huchra.
S. M. Hughes, and G. D. Illingworth, Dis-
tance to the Virgo cluster galaxy Ml 00
from Hubble Space Telescope observa-
tions of Cepheids, Nature 371, 757-762,
1994.

5282 Freedman, W. L., B. F. Madore, P. B. Stet-
son, S. M. G. Hughes, J. A. Holtzman, J. R.
Mould, J. T Trauger, J. S. Gallagher HI, G.
E. Ballester, C. J. Burrows, S. Casertano, J.
T Clarke, D. Crisp, L. Ferrarese, H. Ford,
J. A. Graham, R. E. Griffiths, J. J. Hester, R.

128

CARNEGIE INSTITUTION

Hill, J. G. Hoessel, J. Huchra, R. C. Ken-
nicutt, P. A. Scowen, B. Sparks, K. R.
Stapelfeldt, A. M. Watson, and J. West-
phal, First Hubble Space Telescope obser-
vations of the brightest stars in the Virgo
galaxy M100 = NGC 4321, Astrophys. J.
(Lett.) 435, L31-L34, 1994. (No reprints
available)

5283 Graham, J. A., Interaction between Her-
big Ae/Be stars and the surrounding
medium, in The Nature and Evolutionary
Status ofHerbig Ae/Be Stars, P. S. The, M. R.
Perez, and E. P. J. van den Heuvel, eds., pp.
363-368, Conference Series, Vol. 62,
Astronomical Society of the Pacific, San
Francisco, 1994.

Graham, J. A., and W. P. Chen, Ageing

jets from low-mass stars, Astron. }., in
press.

5258 Graham, J. A., C. M. Wade, and R. M.
Price, Bart J. Bok, April 28, 1906-August 5,
1983, in Biographical Memoirs of the National
Academy of Sciences, Vol. 64, pp. 73-97, Na-
tional Academy Press, Washington, D.C.,
1994. (No reprints available.)

5234 Hardy, S. J., The Earth and space sciences
at Carnegie: a pictorial sampler from the
first six decades, in The Earth, the Heavens,
and the Carnegie Institution of Washington,
G. A. Good, ed., pp. 237-252, American
Geophysical Union, Washington, D.C.,
1994.

5260 Hartmann, L., A. P. Boss, N. Calvet, and
B. Whitney, Protostellar collapse in a self-
gravitating sheet, Astrophys. J. (Lett.) 430,
L. 49-L52, 1994.

Hauri, E. H., and S. R. Hart, Constraints

on melt migration from mantle plumes: a
trace element study of peridotite xenoliths
from Savai'i, Western Samoa, /. Geophys.
Res., in press.

5272 Helffrich, G., and I. S. Sacks, Scatter and
bias in differential PKP travel times and
implications for mantle and core
phenomena, Geophys. Res. Lett. 21, 2167-
2170, 1994.

5267 Helffrich, G., P. Silver, and H. Given,
Shear wave splitting variation over short
spatial scales on continents, Geophys. J. Int.
229,561-573,1994.

5229 Hibbard, J. E., P. Guhathakurta, J. H. van
Gorkom, and F. Schweizer, Cold, warm,
and hot gas in the late-stage merger NGC
7252, Astron. J. 107, 67-89, 1994.

5257 Hughes, S. M. G., P. B. Stetson, A. Turner,
R. C. Kennicutt, Jr., R. Hill, M. G. Lee, W.
L. Freedman, J. R. Mould, B. F. Madore, L.
Ferrarese, H. C. Ford, J. A. Graham, J. G.
Hoessel, and G. D. Illingworth, The Hub-
ble Space Telescope extragalactic distance

scale key project. II. Photometry of WFC
images of M81, Astrophys. }. 428, 143-156,
1994. (No reprints available.)

5271 Ishikawa, T., and E. Nakamura, Origin of
the slab component in arc lavas from
across-arc variation of B and Pb isotopes,
Nature 3 70, 205-208, 1 994.

5244 James, D. E., and J. A. Snoke, Structure
and tectonics in the region of flat subduc-
tion beneath central Peru. I: crust and up-
permost mantle, /. Geophys. Res. 99, 6899-
6912, 1994.

James, D. E., J. A. Snoke, L. C. Ribotta,

and R. Kuehnel, Seismic studies of con-
tinental lithosphere beneath SE Brazil,
Anais da Academia Brasileira de Ciencias, in
press.

Johnson, K. E., R. S. Harmon, S. Moor-
bath, D. F. Strong, J. D. Morris, and J. M.
Richardson, Augustine Volcano, Alaska:
isotopic and trace element constraints on
magmatic components, Contrib. Mineral.
Petrol, in press.

5252 Johnston, M. J. S., A. T. Linde, and D. C.
Agnew, Continuous borehole strain in the
San Andreas fault zone before, during,
and after the 28 June 1992, Mw 7.3 Landers,
California, earthquake, Bull. Seismol. Soc.
Amer. 84, 799-805, 1994.

Kaneshima, S., and P. G. Silver, Aniso-
tropic loci in the mantle beneath central
Peru, Phys. Earth Planet. Inter., in press.

Kenney, J. D. P., V. C. Rubin, P. Planesas,

and J. S. Young, Gas filaments in the col-
lisional debris of NGC 4438, Astrophys. J.,
in press.

5251 Koeberl, C, W. U. Reimold, and S. B.
Shirey, Saltpan impact crater, South
Africa: geochemistry of target rocks, brec-
cias, and impact glasses, and osmium
isotope systematics, Geochim. Cosmochim.
Acta 58, 2893-2910, 1994.

5237 Koeberl, C, W. U. Reimold, S. B. Shirey,
and F. G. Le Roux, Kalkkop Crater, Cape
Province, South Africa: confirmation of
impact origin using osmium isotope sys-
tematics, Geochim. Cosmochim. Acta 58,
1229-1234, 1994.

5242 Koeberl, C, V. L. Sharpton, B. C.
Schuraytz, S. B. Shirey, J. D. Blum, and L.
E. Marin, Evidence for a meteoritic com-
ponent in impact melt rock from the Chic-
xulub structure, Geochim. Cosmochim. Acta
58, 1679-1684, 1994.

Koeberl, C, and S. B. Shirey, Re-Os

isotope study of rocks from the Manson
impact structure, Iowa, in The Manson Im-
pact Structure, Iowa, C. Koeberl and R. R.
Anderson, eds., Special Paper, Geological
Society of America, Boulder, Colo., in

TERRESTRIAL MAGNETISM

129

press.

Lambert D. D., S. B. Shirey, and S. C.

Bergman, A Proterozoic lithospheric
mantle source for the Prairie Creek
lamproites: Re-Os and Sm-Nd isotopic
evidence, Geology, in press.

Lambert, D. D., R. J. Walker, J. W. Mor-
gan, S. B. Shirey, R. W. Carlson, M. L.
Zientek, B. R. Lipin, M. S. Koski, and R. L.
Cooper, Re-Os and Sm-Nd isotope
geochemistry of the Stillwater Complex,
Montana: implications for the pedo-
genesis of the J-M Reef, /. Petrol, in press.

5266 Lavery, R. J., and J. P. Henry, Imaging of
"Butcher-Oemler" blue galaxies at a red-
shift of 0.2, Astrophys. J. 426, 524-534, 1994.

5235 Leeman, W. P., M. J. Carr, and J. D. Mor-
ris, Boron geochemistry of the Central
American Volcanic Arc: constraints on the
genesis of subduction-related magmas,
Geochim. Cosmochim. Acta 58, 149-168,
1994. (No reprints available.)

Levinson, H. E, M. J. Duncan, and G. W.

Wetherill, Secular resonances and com-
etary orbits in the p Pictoris system, Na-
ture, in press.

5273 Linde, A. T, I. S. Sacks, M. J. S. Johnston,
D. P. Hill, and R. G. Bilham, Increased
pressure from rising bubbles as a
mechanism for remotely triggered seis-
micity, Nature 371, 408-110, 1994.

Lissauer, J. J., J. B. Pollack, G. W.
Wetherill, and D. J. Stevenson, Formation
of the Neptune system, in Neptune, D.
Cruikshank, ed., University of Arizona
Press, Tucson, in press.

Martin, C. E., R. W Carlson, S. B. Shirey,

F. A. Frey, and C.-Y. Chen, Os isotopic
variation in basalts from Haleakala Vol-
cano, Maui, Hawaii: a record of magmatic
processes in oceanic mantle and crust,
Earth Planet. Sci. Lett., in press.

5228 McGovern, P. J., and S. C. Solomon, State
of stress, faulting, and eruption charac-
teristics of large volcanoes on Mars, /.
Geophys. Res. 98, 23553-23579, 1993.

5255 McNamara, D. E., T. J. Owens, P. G. Sil-
ver, and F. T. Wu, Shear wave anisotropy
beneath the Tibetan Plateau, /. Geophys.
Res. 99, 13655-13665, 1994.

Morris, J. D., L. Brown, I. S. Sacks, and F.

Tera, Subduction and volcanism, Sci.
Amer., in press.

5232 Morris, J., J. Ryan, and W. P. Leeman, Be
isotope and B-Be investigations of the his-
toric eruptions of Mt. Vesuvius,/. Volcanol.
Geotherm. Res. 58, 345-358, 1993.

5222 Myhill, E. A., and A. P. Boss, Protostellar
hydrodynamics: constructing and testing
a spatially and temporally second-order

accurate method. II. Cartesian coor-
dinates, Astrophys. }. Suppl. Ser. 89, 345-
359, 1993.

5263 Namiki, N., and S. C. Solomon, Impact
crater densities on volcanoes and coronae
on Venus: implications for volcanic resur-
facing, Science 265,929-933, 1994.

5245 Norabuena, E. O., J. A. Snoke, and D. E.
James, Structure of the subducting Nazca
plate beneath Peru, /. Geophys. Res. 99,
9215-9226,1994.

Ocola, L. C, J. H. Luetgert, L. T. Aldrich,

R. P. Meyer, and C. E. Helsley, Velocity
structure of the coastal region of southern
Peru from seismic refraction /wide-angle
reflection data, /. Geodynamics, in press.

5243 Pearson, D. G., F. R. Boyd, S. E. Haggerty,
J. D. Pasteris, S. W. Field, P. H. Nixon, and
N. P. Pokhilenko, The characterisation and
origin of graphite in cratonic lithospheric
mantle: a penological carbon isotope and
Raman spectroscopic study, Contrib.
Mineral. Petrol. 115, 449-466, 1994. (No
reprints available.)

Pearson, D. G., R. W. Carlson, S. B. Shirey,

F. R. Boyd, and P. H. Nixon, The stabilisa-
tion of Archaean lithospheric mantle: a
Re-Os isotope study of peridotite
xenoliths from the Kaapvaal and Siberian
cratons, Earth Planet. Sci. Lett., in press.

Pearson, D. G., G. R. Davies, and P. H.

Nixon, Ultrahigh pressure (diamond
facies) orogenic ultramafic rocks, in
Ultrahigh Pressure Metamorphism, R. G.
Coleman and X. Wang, eds., Cambridge
University Press, in press.

Pearson, D. G., S. B. Shirey, R. W. Carlson,

F. R. Boyd, N. P. Pokhilenko, and N.
Shimizu, Re-Os, Sm-Nd and Rb-Sr isotope
evidence for thick Archaean lithospheric
mantle beneath the Siberian craton
modified by multi-stage metasomatism,
Geochim. Cosmochim. Acta, in press.

5259 Pollitz, F. F, and I. S. Sacks, Fault model
of the 1891 Nobi earthquake from historic
triangulation and leveling, /. Phys. Earth
42,1-43,1994.

5280 Press, F., Humankind and Earth's
natural system, Geotimes 39 (no. 1), 4, 1994.
(No reprints available.)

Press, F, Growing up in the Golden Age

of science, Annu. Rev. Earth Planet. Sci., in
press.

5289 Rabinowitz, D. L., The size and shape of
the near-Earth asteroid belt, Icarus 111,
364-377, 1994.

Rabinowitz, D. L., E. Bowell, E. M.
Shoemaker, and K. Muinonen, The
population of Earth-crossing asteroids, in
Hazards Due to Comets and Asteroids, T

130

CARNEGIE INSTITUTION

Gehrels, M. S. Matthews, and M. L. Guer-
rieri, eds., University of Arizona Press,
Tucson, in press.
5279 Reagan, M. K., J. D. Morris, E. A. Her-
rstrom, and M. T. Murrell, Uranium series
and beryllium isotope evidence for an ex-
tended history of subduction modifica-
tion of the mantle below Nicaragua,
Geochim. Cosmochim. Acta 58, 4199^212,
1994. (No reprints available)

5230 Rubin, V. C., Kinematics of NGC 4826: a
Sleeping Beauty galaxy, not an evil eye,
Astron. J. 107, 173-183, 1994.

5264 Rubin, V. C., Multi-spin galaxies, Astron.
J. 208,456^67,1994.

5236 Russo, R. M., and P. G. Silver, Trench-
parallel flow beneath the Nazca plate from
seismic anisotropy, Science 263, 1105-1111,
1994.

Russo, R. M., and P. G. Silver, Mantle

flow and the making of the Andes, Natural
History, in press.

Russo, R. M., and A. Villasenor, The 1946

Hispaniola earthquakes and the tectonics
of the North American-Caribbean plate
boundary zone, northeastern Hispaniola,
/. Geophys. Res., in press.

Rydelek, P. A., and I. S. Sacks, Earth-
quake "quanta" as an explanation for ob-
served magnitudes and stress-drops, Bull.
Seismol. Soc. Amer., in press.

5231 Sauber, J., W. Thatcher, S. C. Solomon,
and M. Lisowski, Geodetic slip rate for the
eastern California shear zone and the
recurrence time of Mojave desert
earthquakes, Nature 367, 264-266, 1994.

5227 Schiotte, L., B. T. Hansen, S. B. Shirey,
and D. Bridgwater, Petrological and
whole rock isotopic characteristics of tec-
tonically juxtaposed Archaean gneisses in
the Okak area of the Nain Province,
Labrador: relevance for terrane models,
Precambrian Res. 63, 293-323, 1993. (No
reprints available.)

Schweizer, E, Effects of late mergers on

stellar populations in E and SO galaxies, in
Stellar Populations, P. C. van der Kruit, ed.,
IAU Symposium No. 164, Kluwer Aca-
demic Publishers, Dordrecht, in press.

5223 Schweizer, E, and P. Seitzer, Spectra of
two luminous young globular clusters in
the merger remnant NGC 7252, Astrophys.
}. (Lett.) 417, L29-L32, 1993.

5275 Shirey, S. B., K. W. Klewin, J. H. Berg, and
R. W. Carlson, Temporal changes in the
sources of flood basalts: isotopic and trace
element evidence from the 1100 Ma old
Keweenawan Mamainse Point Forma-
tion, Ontario, Canada, Geochim. Cos-
mochim. Acta 58, 4475^1490, 1994.

Silver, P. G., and M. K. Savage, The inter-
pretation of shear-wave splitting para-
meters in the presence of two anisotropic
layers, Geophys. J. Int., in press.

5253 Simons, M., B. H. Hager, and S. C. Solo-
mon, Global variations in the geoid/
topography admittance of Venus, Science
264, 798-803, 1994.

5224 Sims, P. K., J. L. Anderson, R. L. Bauer, V.
W. Chandler, G. N. Hanson, J. Kalliokoski,
G. B. Morey, M. G. Mudrey, Jr., R. W.
Ojakangas, Z. E. Peterman, K. J. Schulz, S.
B. Shirey, E. I. Smith, D. L. Southwick, W.
R. Van Schmus, and P. W. Weiblen, The
Lake Superior region and Trans-Hudson
orogen, in Precambrian: Conterminous U.S.,
J. C. Reed, Jr., et al, eds., Ch. 2, pp. 11-120,
Geology of North America, Vol. C-2,
Geological Society of America, Boulder,
1993. (No reprints available.)

5254 Solomon, S. C, The geophysics of Venus
(in Japanese), Parity Physical Science
Magazine 9 (no. 1), 13-22, 1994. (No re-
prints available.)

5250 Solomon, S. C, Plate tectonics: stirring
times for Mars, Nature 369, 606-607, 1994.

Solomon, S. C, Venus geology and geo-
physics, in Encyclopedia of Planetary Scien-
ces, J. H. Shirley and R. W. Fairbridge, eds.,
Van Nostrand Reinhold, New York, in
press.

Toomey, D. R., S. C. Solomon, and G. M.

Purdy, Tomographic imaging of the shal-
low crustal structure of the East Pacific
Rise at 9°30'N, /. Geophys. Res., in press.

5269 VanDecar, J. C, and R. Snieder, Obtain-
ing smooth solutions to large, linear in-
verse problems, Geophysics 59, 818-829,
1994.

5262 Walker, C. K., G. Narayanan, and A. P.
Boss, Spectroscopic signatures of infall in
young protostellar systems, Astrophys. J.
431, 767-782, 1994. (No reprints available.)

5248 Wetherill, G. W., Possible consequences
of absence of "Jupiters" in planetary sys-
tems, Astrophys. Space Sci. 212, 23-32, 1994.

5277 Wetherill, G. W, Provenance of the ter-
restrial planets, Geochim. Cosmochim. Acta
58, 4513^520, 1994.

Wetherill, G. W., The formation of habit-
able planetary systems, in Proceedings of
the Conference on Habitable Systems, NASA
Ames Research Center, January 1994, in
press.

5225 Wetherill, G. W., and G. R. Stewart, For-
mation of planetary embryos: effects of
fragmentation, low relative velocity, and
independent variation of eccentricity and
inclination, Icarus 106, 190-209, 1993.

5221 Wilcock, W. S. D., M. E. Dougherty, S. C.

TERRESTRIAL MAGNETISM

131

Solomon, G. M. Purdy, and D. R. Toomey,
Seismic propagation across the East
Pacific Rise: finite difference experiments
and implications for seismic tomography,
/. Geophys. Res. 98, 19913-19932, 1993.
5239 Williams, D. R., and G. W. Wetherill, Size
distribution of collisionally evolved aster-
oidal populations: analytical solution for

self-similar collision cascades, Icarus 107,
117-128, 1994.
5261 Zhou, S., H. M. Burner, N. J. Evans EL R
Giisten, M. L. Butner, and L. G. Mundy, CS
multitransitional study of density dis-
tribution in star-forming regions. II. The
S140 region, Astrophys. J. 428, 219-232,
1994. (No reprints available.)

Personnel

Research Staff

L. Thomas Aldrich, Emeritus

Alan P. Boss

Louis Brown, Emeritus1

Richard W. Carlson

W. Kent Ford, Jr., Emeritus

John A. Graham2

Erik H. Hauri3

David E. James

Alan T Linde

Julie D. Morris4

Vera C. Rubin2

I. Selwyn Sacks

Francois Schweizer2

Steven B. Shirey

Paul G. Silver

Sean C. Solomon, Director

Fouad Tera

George W. Wetherill

Senior Research Fellow

Frank Press, Cecil and Ida Green Senior
Fellow5'6

Postdoctoral Fellows and Associates

Guilhem Barruol, NSF Associate, and Bourse
Lavoisier Fellow, French Ministry of
Foreign Affairs5,7
Ingi Th. Bjarnason, Carnegie Fellow
Harold M. Butner, Carnegie Fellow8
Thomas S. Duffy, Grove Carl Gilbert

Fellow5-9
Prudence N. Foster, NASA Associate10
Tsuyoshi Ishikawa, Carnegie Fellow11
Russell J. Lavery, Carnegie Fellow12
Lanbo Liu, Carnegie Fellow13
Elizabeth A. Myhill, Carnegie Fellow14
David L. Rabinowitz, NASA Associate15
Raymond M. Russo, Jr., NSF Associate
Larry P. Solheim, Carnegie Fellow5'16

John C. VanDecar, Harry Oscar Wood

Fellow5'8
Elisabeth Widom, Carnegie Fellow17
Cecily J. Wolfe, Postdoctoral Investigator18

Predoctoral Fellozvs

Lori K. Herold, Massachusetts Institute of

Technology
Nguyen Hoang, University of Illinois,

Chicago
Patrick J. McGovern, Massachusetts Institute

of Technology
Noriyuki Namiki, Massachusetts Institute of

Technology
Mark Simons, Massachusetts Institute of

Technology

Research Interns

Christopher Bareford, Concord-Carlisle

High School, Massachusetts19
Steven C. Schoenecker, Princeton University18
Christoph Trachslin, Kantonschule, Zug,

Switzerland20
Heather M. Weir, George Mason University21

Supporting Staff

Michael J. Acierno, Computer Systems

Manager
John R. Almquist, Library Volunteer
Maceo T. Bacote, Engineering Apprentice522
Georg Bartels, Instrument Maker
Gary A. Bors, Building Engineer5'23
Mary McDermott Coder, Editorial Assistant
H. Michael Day, Facilities Manager5
Roy R. Dingus, Building Engineer5
Janice Scheherazade Dunlap, Technical Typist
John A. Emler, Laboratory Technician
Pablo D. Esparza, Maintenance Technician5'22
Rosa Maria Esparza, Clerk-Receptionist
Shaun J. Hardy, Librarian5

132

CARNEGIE INSTITUTION

Mikie Ishikawa, Library Volunteer
Sandra A. Keiser, Scientific Computer

Programmer
William E. Key, Building Engineer5
Randy A. Kuehnel, Geophysical Technician
David C. Kuentz, Geochemistry Laboratory

Technician
D. Carol Lynch, Executive Secretary5'24
P. Nelson McWhorter, Instrument Maker
Ben K. Pandit, Electronics Engineer
Lawrence B. Patrick, Maintenance

Technician5
Glenn R. Poe, Electronics Research Specialist
Daniela D. Power, Geophysical Research

Assistant
Pedro J. Roa, Maintenance Technician5
Roy E. Scalco, Engineering Apprentice5
Michael Seemann, Design Engineer —

Mechanical, Shop Manager
Terry L. Stahl, Fiscal Officer
David Weinrib, Fiscal Assistant
Merri Wolf, Library Technical Assistant5

Visiting Investigators

Craig R. Bina, Northwestern University
Jean Carignan, Universite de Montreal,

Canada
Ines Lucia Cifuentes, Carnegie Institution of

Washington
Timothy J. Clarke, University of Illinois,

Urbana
Sonia Esperanca, Deakin University,

Australia
Mathias Franke, Venezuelan National Oil

Company

William K. Hart, Miami University
Anthony J. Irving, University of Washington
Christopher R. Kincaid, University of Rhode

Island
Christian Koeberl, University of Vienna,

Austria
Allison M. Macfarlane, George Mason

University
Sobhi Nasir, United Arab Emirates

University
Suzanne W. Nicholson, U.S. Geological

Survey
Jeffrey J. Park, Yale University
Martha K. Savage, University of Nevada,

Reno
Patrick O. Seitzer, University of Michigan,

Ann Arbor
David W. Simpson, Incorporated Research

Institutions for Seismology
J. Arthur Snoke, Virginia Polytechnic

Institute and State University
Ragnar K. Stefansson, Iceland

Meteorological Office
Nathalie J. Valette-Silver, National

Oceanographic and Atmospheric

Administration
Leonid L. Vanyan, Academy of Sciences,

Moscow, Russia
Antonio Villasenor, Instituto de Ciencias de

la Tierra (Jaume Almera), Barcelona, Spain
Elisabeth Widom, National Institute of

Standards and Technology
David R. Williams, National Space Science

Data Center
Dapeng Zhao, California Institute of

Technology

Retired January 31, 1994

2Holds additional

appointment as Adjunct
Staff Member, The
Observatories of the
Carnegie Institution

3From February 1, 1994

4To lanuary 1, 1994

5Joint appointment with the
Geophysical Laboratory

6From September 15, 1993
7From September 25, 1993
8From September 28, 1993
9To June 30, 1994
10From November 8, 1993
"From September 1, 1993
12To August 17, 1993
13From November 5, 1993
14From May 1, 1994
15From September 1, 1993

16From September 9, 1993
17To December 31, 1993
18FromJune 1,1994
19To July 31, 1993
20To August 8, 1993
21To May 31, 1994
22From May 16, 1994
23To April 8, 1994
24From September 24, 1993

The Observatories

^%:.\

■'■:';-v\,?vv>'./--! v""ic:-;;s:; .<;,■■:;«: jg;

du Pont Telescope, Las Campanas

Postdoctoral fellows at the Observatories, 1993-1994. Bottom row, left to
right: Bob Hill, Ann Zabludoff, Dennis Zaritsky. Top row: Steven Majewski,
Andrew McWilliam, Jeff Willick, Michael Rauch. Not present: Steven Landy.

The Director's Introduction

Astronomy has become in this century a profoundly historical
science. The explanation for the world that modern telescopes are
revealing is to be found in origins, in process, and in contingency.
Physics underlies it all, but answers to the question "Why are things
the way they are?" are stories. There are two quite different routes to
the discovery of these stories. The first and most obvious route is via
the isolation and study of old things. The second is by the study of
things sufficiently remote that light from them has taken a significant
fraction of the age of the universe to reach us. It is only in the last
decade that much progress has been made along this second route, but
there is little doubt that its exploration will occupy a major fraction of
the time of the large telescopes now coming into operation. Growth
areas of modern astronomy are to be found in those subjects where
investigations following both of these routes converge.

The two essays contributed from the Carnegie Observatories to this
Year Book give life to these generalities. Andrew Mc William, a
McClintock Postdoctoral Fellow in the Pasadena department, who has
been working with staff member George Preston, has been making
major advances in the study of the chemical elements to be found in the
oldest known stars. Michael Rauch, a postdoctoral associate working
with staff member Ray Weymann, has been pioneering in the study of
abundances of the elements in remote intergalactic matter. In the near
future, these two approaches will converge, and, if the Observatories
are careful to cherish intellectual diversity, the large telescopes of the
Magellan Project will help bring that about.

— Leonard Searle

135

136

CARNEGIE INSTITUTION

Atoms and Stars

by Andrew McWilliam

What are stars made from? How did the atoms that we and our
world are composed of, come into existence?
It is possible to answer both of these questions using a
spectrometer at the focus of a large telescope. The Carnegie
Observatories' 2.5-meter du Pont Telescope is equipped
with an efficient echelle spectrometer, built by Carnegie
staff member Steve Shectman. Stellar spectra obtained
with this instrument exhibit many dark lines imposed
on a continuum. The lines are produced by the
absorption of light by various elements present in the
stellar atmosphere; the line strengths can be used to
measure elemental abundances. Spectra of three
extremely metal poor stars are shown in Figure 1. (Here
the term "metals" refers to elements other than
hydrogen and helium.) Although the three stars have
similar structural characteristics, the strengths of certain
absorption features differ, indicating subtle differences
in chemical composition. Andrew McWilliam

Fig. 1 . Spectra of three very-
metal-poor stars similar in
temperature and mass but differing in
metallicity. The valleys are, in
general, absorption features caused
by the presence of certain elements.
Notice the strong absorption features
due to heavy elements in the bottom
star; the Co I, Eu II, and strong Fe I
features, for example, can be readily
compared vertically. Metallicities are
1/1300 (top star), 1/300 (middle star),
and 1/1100 (bottom star) of the solar
value. The spectra were obtained
with the echelle spectrograph at the
du Pont Telescope, Las Campanas.

CS 22878-101

4120

4125

4130

4135

Wavelength (A)

15

BB

O)10
o

c

CO
TJ

c
13
-Q

< E

a Q.

Ex

A ^^ neutron capture

I I r I |

Fepeak ^#11^^/^^^ J^ J/^Ji

A

▲

0 50 100 150 200 250

Atomic Weight

Fig. 2. The abundance distribution ot elements in the solar system. Principal
nucleosynthesis sources are shown: BB, Big Bang; Q, quiescent burning in stellar
interiors; Ex, explosive burning during a supernova episode; neutron capture,
r-process or s-process (as marked) neutron capture in stars. (Odd numbered
elements only are shown; y-axis units are logarithmic, abundance per 106 Si atoms.)

The chemical composition of the solar system has been studied
extensively, using high-quality spectra of the Sun (such as those
obtained at Mount Wilson Observatory), laboratory analyses of
meteorites, and, since the advent of space travel, solar wind samples
(such as those acquired during the Apollo 11 mission to the Moon). As
a result, the relative abundances of most of the extant isotopes in the
solar system are known. The "Solar Abundance Distribution" is shown
in Figure 2; one can see several peaks and valleys in the trend of
abundance with atomic weight. One would rightly suppose that these
features are related to the formation processes involved in the synthesis
of each isotope. In fact, the abundance distribution is like a fingerprint,
with certain patterns betraying nucleosynthesis by specific nuclear
processes.

Spectroscopic surveys of many stars show not only that overall
metal abundances vary over a ten-thousandfold range, but also that
many stars were formed with chemical abundance patterns very
different from the solar system's. Furthermore, when colors and
luminosities are used to measure stellar ages, one finds a general
correlation of increasing metallicity with decreasing stellar age; in other
words, the metallicity of stars in the Galaxy increased with time.

The story of nucleo-genesis that has emerged begins with the
production of all hydrogen, most of the helium, and minute amounts of
lithium, beryllium, and boron in the Big Bang origin of the universe.
Nearly all other elements are thought to have been produced in the
nuclear furnaces of stellar interiors. It is the transmutation of elements
in these nuclear furnaces, from light to heavy nuclei, which provide the
stars with the energy necessary to delay gravitational collapse, and by
which the stars shine.

stellar surface

collapsing core

Fig. 3. Cutaway illustrating onion-layer structure of a typical massive star just prior
to its supernova explosion. In each zone are shown the relevant nuclear-burning
process and the prominent constituents. Typical densities and temperatures are
indicated at each boundary.

Stars begin their lives by burning hydrogen into helium; in their
later phases, when the hydrogen is exhausted in the core, the helium
ashes are burned into carbon and oxygen under higher temperatures
and pressures. During its lifetime a star may go through many
nuclear-burning phases if it is of sufficiently high mass. There are six
major burning phases which can occur in the quiescent life of a massive
star: stages of hydrogen, helium, carbon, neon, oxygen, and silicon
burning. In each stage the fuel is the product of the previous burning
stage; as a consequence, progressively heavier elements are built up in
the cores of massive stars, in an arrangement resembling the layers of
an onion. This can continue only until the core consists of iron, because
iron is the most stable element, whereupon no further fusion or fission
reactions can occur with net release of energy. Finally, the star runs out
of quiescent nuclear-burning options and a supernova (SN) explosion
ensues. Figure 3 shows the onion-layer arrangement of elements
resulting from successive stages of nuclear burning in a typical massive
star, just prior to the supernova explosion.

During the SN explosion nucleosynthesis includes explosive
oxygen and silicon burning, as well as the synthesis of the iron-peak
nuclei (see Fig. 2) formed by a process called nuclear statistical
equilibrium (or NSE). In NSE the temperatures are so high (3-10 billion
degrees Kelvin) that nuclei are constantly being broken up by
high-energy photons and then reassembled from the fragments. A
statistical equilibrium is quickly achieved, where the number of any
particular isotope is proportional to the energetic stability of its
nucleus, the most tightly bound nucleus becoming the most abundant
species (because it is the most difficult to disintegrate). When the SN
material finally cools to about 3 billion K (approximately 1 second after

THE OBSERVATORIES 139

the supernova detonation), the isotopes are said to "freeze-out,"
thereafter retaining the abundance pattern reached during NSE. As
early as 1946 Sir Fred Hoyle noted the similarity of the solar system
iron-peak abundance pattern and the abundances predicted from this
equilibrium process. Elements heavier than the iron peak are thought to
be produced by the addition of neutrons onto iron-peak nuclei. This
neutron capture can take place on rapid or slow time-scales, from about
a second to several hundred years; hence these processes are named the
r-process and s-process respectively. Both r- and s-process neutron
capture produce distinct peaks in the abundance distribution, as can be
seen in Figure 2. The observation of these peaks in the solar abundance
distribution is compelling evidence in favor of the operation of both
neutron-capture processes.

One can think of star formation in generations, each generation
forming from the interstellar gas as composed at the given time. Each
generation produces new stars varying in mass from about 0.08 to
perhaps 100 solar masses. The lifetimes of these stars differ
considerably; a high-mass star of 50 solar masses will live for
approximately one million years, whereas a low-mass star like our Sun
has a lifetime of about ten billion years. Stars with masses less than
about 0.8 solar masses have lifetimes longer than the age of the Galaxy;
thus it is possible to find stars of this mass from all epochs in Galactic
history.

In each generation of stars the high-mass stars end as supernovae,
thereby increasing the metal content of the Galactic gas out of which
new generations of stars form. Meanwhile the low-mass stars live on,
as a fossil record of the composition of the Galaxy in the location and
the time of their formation.

Because overall metallicity increased with time, it is possible to
learn about the history of element formation in the Galaxy by
measuring the chemical composition of stars of differing overall metal
content. For example, in the 1960's George Wallerstein noticed that the
abundance ratio of Ca to Fe was higher in a sample of metal-poor stars
than in the Sun. Today, this and other, similar abundance trends are
widely thought to be due to nucleosynthesis from a mixture of two
types of SN, differing in proportion from the current proportion of
these SN types.

A recent survey by George Preston, Tim Beers, and Steve Shectman
of the Carnegie Observatories has uncovered a sample of extremely
metal poor stars having metallicities down to 1/10,000 of the solar
metallicity. If a crude assumption is made, then the most extreme of
these stars was born when the Galaxy was only one million years old.
These stars, then, are fossils from the very earliest epoch in Galactic
history. The chemistry of these stars provide information about the
Galaxy's very earliest supernovae, which exploded about 15 billion

140 CARNEGIE INSTITUTION

years ago. Using the du Pont Telescope and echelle spectrograph,
George Preston, Leonard Searle, and I, with Chris Sneden of the
University of Texas, have acquired and analyzed spectra for 33 of the
most metal poor of these stars.

One of our interesting discoveries is that the Cr/Co ratio declines
by a factor of ten from the most metal rich to the most metal poor stars
in our sample. The lowest observed Cr/Co ratios are not predicted by
any published supernova nucleosynthesis calculations; however, lower
values are expected in the very deepest levels of the SN, where critical
parameters and physical processes are not well understood. Therefore,
our observed Cr/Co ratios provide a probe into the deepest layers of
the SN, and may be useful in constraining SN models.

Nucleosynthesis arguments suggest that we may expect
enhancements of other elements near Co; specifically, zinc, gallium, and
germanium (Zn, Ga, and Ge) are interesting candidates. In the case of
Zn strong lines do exist in our stars, but they are at extremely short
wavelengths, below the range of our spectrometer.

Interestingly, measurements of Cr/Zn have been made for the
absorption-line systems arising from galaxies along lines of sight to
distant quasars. Some of these galaxies are about 16 billion light years
away, and are therefore contemporaneous with the formation of our
sample of extremely metal poor stars (see the following article by
Michael Rauch). For example, recent results based on spectra of nine
quasars by Pettini and collaborators, of the Royal Greenwich
Observatory, indicate that Cr/Zn in these distant galaxies is about 1/10
of the solar value. Although Pettini et ah assume that these unusual
ratios are due to selective depletion of Cr onto dust grains, this
assumption is by no means widely accepted as fact. It may be no more
than coincidence that for distant galaxies the Cr/Zn ratios (relative to
the solar value) are similar to the Cr/Co ratios (relative to the solar
value) of our most metal poor stars; yet this similarity is qualitatively
expected. We speculate that the similarity of abundance ratios may be
characteristic of the composition of SN ejecta at very low metallicity.

This link between abundances in Galactic and cosmological objects
will likely lead to greater understanding of both fields of study, and
should therefore be explored further.

Besides Co and Cr abundances, we find that the abundances of Mn,
Al, and the heavy elements Sr and Ba begin to decrease markedly,
relative to iron, below a metallicity of 1/300 of the solar value. We
conclude that SN at these low metallicities were very different than SN
today, and it seems reasonable to us that these differences may have
been due to the effects of stellar mass loss on stellar evolution. At low
metallicity, mass loss from stellar winds is expected to be much
reduced, and this could change the mass range of stars which
ultimately become SN.

THE OBSERVATORIES

141

Finally, we find that there is a large scatter in certain abundance
ratios among metal-poor stars. In particular, we found that star CS
22892-052 possesses an r-process to iron ratio more than forty times the
solar value. A spectrum of this star appears in Figure 1; amazingly, the
figure shows that the strongest line in this portion of the spectrum is
due to europium, an r-process element. We conclude that this scatter is
caused by a real spread in SN production of r-process elements relative
to iron, a quantity for which there are presently no reliable theoretical
predictions. The spread in abundance ratios also indicates that at these
early times the Galactic mixing processes had not yet homogenized the
interstellar gas. Therefore, our abundance analyses may yield
information on the dynamical, as well as the chemical, evolution of the
Galaxy.

It is remarkable that from spectral analysis of extremely metal poor
stars, we can learn about the nuclear and stellar physics of element
synthesis occurring ten billion years before the birth of the solar
system, deep within supernova explosions, in an environment with
peak temperatures of several billions of degrees Kelvin.

It seems impossible not to feel a great connection with the universe
when one realizes the significance of these nucleosynthesis processes in
our daily lives. After all, the iron in the hemoglobin of our blood was
made by nuclear statistical equilibrium and explosive silicon burning;
the calcium in our teeth and bones was made by explosive oxygen and
silicon burning, and the fluorine we brush those teeth with was
produced by a rare neutrino interaction with neon; the iodine in our
thyroid glands was produced by r-process neutron capture; the carbon
and oxygen in our tissues was synthesized during helium burning, and
the hydrogen in our tissues and fluids was forged during the Big Bang
perhaps 20 billion years ago.

Entrance to the new addition at the Observatories' Pasadena office building.

142 CARNEGIE INSTITUTION

Spectroscopy of Gas at High Redshift

by Michael Ranch

Thus the explorations of space end on a note of uncertainty. And
necessarily so. We are, by definition, in the very center of the observable
region. We know our immediate neighborhood rather intimately. With
increasing distance, our knowledge fades, and fades rapidly. Eventually,
we reach the dim boundary — the utmost limits of our telescopes. There,
we measure shadows, and we search among ghostly errors of
measurement for landmarks that are scarcely more substantial....*

The above quotation is from the final chapter of Edwin Hubble' s
classic book The Realm of the Nebulae, a compendium of what was
known about observational cosmology in the 1930's. Hubble's dramatic
description refers to observations of distant galaxies and to the
frustrating observational constraints that prevent
astronomers from reaching further out into space.
Writing nowadays, Hubble would presumably give a
more optimistic account. True, "ghostly errors of
measurement" may still occasionally be met, but the
"landmarks" have gained considerably in substance
during the past fifty years.

Hubble did not live to witness the birth of a
branch of astronomy devoted, not metaphorically but
literally, to the study of "shadows," a specialized science
which would extend the borders of knowledge in space
and time far beyond what he could have envisioned in
his lifetime.

This development began in the 1960's with the ...

discovery of a new class of astronomical objects, the
so-called QSOs (Quasi-Stellar Objects, or quasars). As
it turned out, many of these extremely bright light sources — thought to
be caused by violent phenomena in the nuclei of early galaxies — are
located not too far from the edge of the observable universe, the
so-called horizon. In a world of finite age, light from galaxies further
away than the horizon has not yet had time to reach us, even if it was
emitted at the very beginning of the universe. Therefore, the horizon
distance is really a fundamental limit to Hubble's quest and cannot be
transcended even by using arbitrarily large telescopes. Observing the
ultraluminous QSOs, however, we can at least sample distances out to a
significant fraction of the horizon radius, where the nearby galaxies
Hubble studied would long have become invisible.

*Edwin Hubble, The Realm of the Nebulae, p. 36, Yale University Press, New
Haven, 1936, ©Yale University Press.

4500

5000

5500

6000

Wavelength (A)

Fig. 1 . Spectrum of the QSO 001 4+81 3 at redshift 3.4. The ragged appearance
below 5250 A is caused by hundreds of Lyman a absorption lines produced by gas
intervening between the QSO and us. The inset is an enlargement of a small section
taken at higher spectral resolution. At top, it is normalized such that the QSO
continuum becomes a horizontal line, and the individually resolvable absorption
components are indicated by vertical tick marks. As can be seen, the indentations
split into many distinct absorption lines, each representing a gas cloud at a slightly
different velocity of recession.

Soon after the discovery of QSOs it was realized that the ancient
light from these objects contains a continuous record of the physical
conditions of the matter along the light path. When QSO light is
analyzed with spectroscopic means, numerous indentations are found
to be imprinted on the otherwise rather smooth continuum of the QSO
spectrum. These features can be identified as known atomic absorption
lines at known wavelengths arising in gas intervening between us and
the QSO. Each of those atomic transitions casts a characteristic
"shadow" onto the spectrum of the light source. The light from a
distant QSO intersects hundreds of absorbing gas clouds on its way to
us; because of the expansion of the universe the spectral signature of
each of these clouds is shifted increasingly to the red with increasing
distance, so the absorption features line up along the spectrum like
beads in a necklace (see Fig. 1). The "redshift," derived from the ratio
between the observed "reddened" and the terrestrial wavelength of an
absorption line, is a convenient measure of the distance and
lookback-time to an absorbing object. Since light travels with a finite
velocity we see distant objects as they appeared when the light was
emitted. Thus, observations of QSOs enable us to probe the universe in
space and time: far-away and long-ago are inseparable. An object at
redshift 3, for example, is now at a distance halfway out to the horizon,

144 CARNEGIE INSTITUTION

and appears as it was when the universe was about 10% of its present
age.

Over the past two decades, spectroscopy of lines of sight to QSOs
has provided us with a wealth of information about the chemical
abundances of the intervening gas, its temperature and kinematics, the
intergalactic radiation field, and the cosmological distribution of these
intervening objects throughout most of the history of the universe. It
has become realized that the shadows in the QSO spectra arise from
quite a range of astronomical objects, and that the variety in the
physical appearance of absorption systems is larger and more bizarre
than whatever we see nearby. Galaxies as we know them from their
emission (which is what traditional astronomy is about) extend a much
larger cross-section when viewed in absorption against QSOs, an
indication that considerable parts of these objects are invisible in
imaging studies. This is a consequence of the enormous sensitivity of
absorption spectroscopy. To see a galaxy in emission requires billions of
stars to shine simultaneously, and even then only the central part of a
galaxy is bright enough to be detected, whereas a tiny fraction of a solar
mass in absorbing gas (mostly hydrogen) suffices to be detected easily
in a QSO spectrum.

Of course there is a price to be paid: the picture QSO spectroscopy
draws of the material contents of the universe is by necessity coarse
compared to the detailed studies possible in our Galactic neighborhood
with stellar spectroscopy, as described by Andy McWilliam in the
preceding article. First, because of their enormous distances QSOs are
much fainter than typical stars in our Galaxy; this restricts extragalactic
observations at present to the few most abundant chemical elements
having the strongest absorption lines. Second, the stellar astronomer is
free to choose individual stars of particular interest for study, while the
QSO observer is stuck with a single line of sight of unpredictable
orientation through a whole galaxy, much like a drilling core. A line of
sight to a QSO will always pierce through many layers of interstellar
gas and probe many different stellar environments at the same time, so
we can only expect to obtain average values for the properties of the
gas we observe.

Keeping these cautionary remarks in mind, what does
spectroscopy of high-redshift gas tell us about the early universe? Not
surprisingly, galaxies and galaxy precursors account for at least some of
the absorbers, a connection firmly established only a few years ago
(pioneered by J. Bergeron and collaborators) when imaging studies at
optical wavelengths and in the radio regime detected emission from
objects previously known only in absorption. Those objects turned out
to be rather bright galaxies not unlike our Milky Way, surrounded by
huge, highly ionized gaseous halos responsible for the absorption.
Sometimes the line of sight to the QSO intersects, in addition to the

THE OBSERVATORIES 145

halo clouds, the predominantly neutral hydrogen gas of what is
thought to be a galactic disk or its precursor, leading to a very broad,
"damped" Lyman a absorption line in the spectrum. However, by far
most of the absorption systems show much weaker absorption features
than either the halo or damped Lyman a systems: they belong to a third
class of absorbers called "Lyman a forest" clouds; each QSO spectrum
is covered by a dense "forest" of hundreds of hydrogen Lyman a
absorption lines arising in these objects. The physical nature of the
forest clouds is still unknown; counterparts in emission have not yet
been discovered, and speculations abound. Infalling gas in the process
of galaxy formation, tidal debris from galaxy-galaxy interactions, dark
galaxies with burned-out stars, and intergalactic gas confined by the
gravity of dark-matter halos are among the less esoteric candidates, and
possibly all of them contribute to some extent to the phenomenon.

Numerous metallicity studies of individual halo or damped Ly a
systems and dozens of surveys for particular metal-absorption features
have been performed during the last fifteen years. The results point to
some kind of overall chemical evolution, in the sense that the
abundances of common elements produced by stellar nucleosynthesis
(such as carbon, silicon, and oxygen) increase with time. Metal
abundances in both halo and damped systems are lower at redshift 3 by
a factor of typically 10-100 relative to solar abundances. This ties in
nicely with the properties of the metal-poor globular cluster stars in our
Galaxy, and we have reason to believe that these objects contain a fossil
record of what we observe — still in the form of gas — in high-redshif t
galaxy halos. Evidence from surveys for absorption systems with the
conspicuous Carbon IV doublet (by Sargent and collaborators at
Palomar) is most easily interpreted as showing a monotonic increase of
the carbon abundance with time, a sign of progressive chemical
enrichment of the halo gas in these objects by stars. Nevertheless, there
is a huge scatter in abundances even at the same epoch. For example, of
two damped Lyman a systems, both at redshift ~2 and lying toward
the same QSO, one has a metal abundance down by almost a factor of
1000 relative to solar values, whereas abundances in the other barely
differ from present-day values. While all the metal-containing systems
are thought to be somehow related to galaxies, most of the weak Lyman
a forest systems may well belong to a pristine intergalactic population
uncontaminated by any stellar nucleosynthesis. At the time of writing
there is no strong evidence suggesting that they contain elements
heavier than helium at all.

Halo or disk stars are not the only sources of chemical elements.
For some time it has been suspected that a peculiar kind of
nucleosynthesis has taken place in QSOs themselves. Work by former
Carnegie postdoc Fred Hamann (now at UCSD) and collaborator Gary
Ferland shows that the nitrogen abundance in redshift-2 QSOs, as

146 CARNEGIE INSTITUTION

derived from QSO emission-line studies, exceeds that of the solar
neighborhood. This result seems to hold for so-called associated
systems, clouds which were probably ejected from the QSO in the past,
some of them with velocities of more than 10,000 km per second.
Patrick Petitjean (Paris), Bob Carswell (Cambridge), and I detected gas
with higher-than-solar carbon and nitrogen abundances in absorbing
clouds close to QSOs at redshift 2. The clouds are seen when the
universe was only about 20% of its present age, so nucleosynthesis
obviously proceeded very rapidly. It is not precisely clear why, though.
An early generation of massive stars has been suggested, as have been
violent nucleosynthetic processes in the hot gaseous accretion disk
surrounding a black hole, the central engine thought to be behind the
QSO phenomenon.

There is clearly nothing like a global chemical abundance ratio at
any epoch after the first stars and galaxies have formed; the
metallicities depend much on local conditions. On the other hand, our
currently favored picture of the universe, the Big Bang model, predicts
the emergence of a characteristic primordial abundance pattern in the
nucleosynthetic events during the first few minutes after the Bang.
Next to hydrogen, helium and the heavier hydrogen isotope,
deuterium, are the most notable among these primordial elements;
unfortunately, they are also among the most difficult ones to detect at
high redshift. The search for these elements in high-redshift gas is
nevertheless of great interest because it should give clues as to the
primordial composition of matter prior to processing by subsequent
generations of stars.

Last year Carswell, Observatories staff member Ray Weymann, and
I observed an absorbing cloud at redshift 3.3 with the Kitt Peak 4-meter
telescope to look for primordial deuterium, an important indicator of
the number of baryons in the universe: the higher the baryon density,
the more deuterium is processed into helium during the first few
minutes after the Big Bang and the less deuterium survives to the
present. Only very few absorption clouds are suitable for such a study:
if the amount of gas present is too large then the nearby hydrogen line
in the spectrum caused by the same cloud completely swamps the
expected deuterium feature; if there is too little gas, then the absorption
signal of deuterium is too weak to be detected. The cloud chosen had
the additional benefit of showing no signs of stellar nucleosynthesis
and thus of stellar processes that could have destroyed primordial
deuterium. Absorption at the putative wavelength position of
deuterium was detected at a level rather stronger than expected on the
basis of theoretical predictions. (This finding is confirmed in
independent work with the Keck telescope by Songaila and
collaborators.) Taken at face value the high deuterium-to-hydrogen
ratio would imply that there may be less baryonic matter in the

THE OBSERVATORIES 147

universe than previously thought. The apparent discrepancy between
the small amount of baryonic matter observed in galaxies and the
larger value based on previous estimates of the deuterium abundance
would disappear. However, it is conceivable that the absorption feature
interpreted as deuterium is contaminated by the hydrogen line of a
nearby unidentified cloud, so the detection should be cautiously
considered primarily an upper limit on the primordial deuterium
abundance. Confirmation or rejection of this result must await
observations of several other clouds.

Helium, the second-most-common element (after hydrogen) has
also remained elusive until recently. Its absorption lines occur in the
far-ultraviolet region, so even at high redshift we can observe them
only above the Earth's atmosphere, with satellites. Early this year
Jakobsen and collaborators, using the Hubble Space Telescope, detected
absorption by Helium II, apparently distributed in a continuous fashion
all over the universe, not only in galaxies or the clouds producing
Lyman a absorption lines. In intergalactic space, the helium-containing
gas should be untouched by stellar nucleosynthesis and should
represent, therefore, gas of primordial origin. This result, if confirmed,
lends strong support to the Big Bang theory, which predicts that most
of the existing helium formed very early in the history of the universe.

From these recent examples it is clear that QSO absorption line
spectroscopy will be one of the growth industries of astronomy for
decades to come. Large telescopes like the Carnegie Observatories'
Magellan, in combination with high-resolution spectrographs, will
allow QSO spectroscopists to catch up with their stellar colleagues, as
far as our knowledge of chemical abundances is concerned. The much
stronger signals collected by these instruments will make many more
chemical elements having only weak absorption lines available for
spectroscopy.

Detailed kinematical studies of the absorption-line profiles will
enable us to track gas motions and witness the process of galaxy
formation in situ, providing information not accessible otherwise.

With increasing sensitivity, fainter (and thus many more) QSOs can
be observed spectroscopically, and we can imagine observing programs
dedicated to mapping the large-scale structure of the universe with
QSO beams — a kind of tomography of space.

A large sample of absorption systems at high redshift may provide
the ultimate reference frame to measure the motion of our solar system
with respect to the rest of the universe.

Once we gain a sufficient understanding of the variety of
phenomena we are observing at high redshift, we may feel prepared to
tackle some of the cosmological questions that were at the focus of
Hubble's research, knowing now that the realm of the nebulae is
embedded in the much larger realm of the shadows.

148

CARNEGIE INSTITUTION

Bibliography

Bershady, M Av M. Hereld, R. G. Kron,
D. C. Koo, J. A. Munn, and S. R. Majewski,
The optical and near-infrared colors of
galaxies. I. The photometric data, Astron.
J. 108, 870, 1994.

Carswell, R. E, M. Rauch, R. J. Wey-
mann, A. J. Cooke, and J. K. Webb, Is there
deuterium in the z = 3.32 complex in the
spectrum of 0014+813?, MNRAS 268, LI,
1994.

Castander, E J., R. S. Ellis, C. S. Frenk, A.
Dressier, and J. E. Gunn, The detection of
x-ray emission from the highest redshift
galaxy clusters, Astrophys. }. Lett. 424, L79,
1994.

Crotts, A. P. S., W. E. Kunkel, and S. R.
Heathcote, SN 1987 A's circumstellar en-
velope. I. The shape of the double-lobed
nebula and its rings, and the distance to
the LMC, Astrophys. J., in press.

Donahue, M., Evolution of clusters and
their intracluster medium, in The Environ-
ment and Evolution of Galaxies: Proceedings
of the Third Teton Summer School held in
Grand Teton National Park, Wyoming,
U.S.A., July 1992, H. Thronson and J. M.
Shull, eds., Kluwer, Dordrecht, p. 409,
1993.

Donahue, M., and J. T. Stocke, Coronal
line emission in cluster cooling flows,
Astrophys. J. 422, 459, 1994.

Donahue, M., with T. J. Courvoisier et al.,
Ground-based observations of PKS2155-
304 in November 1991, Astrophys. /., in
press.

Donahue, M., with R. Edelson et al.,
Multi-wavelength monitoring of the BL
Lac object PKS2155-304. IV. Multi-
wavelength analysis, Astrophys. /., in
press.

Dressier, A., The spectra and morphol-
ogy of galaxies in high-redshift clusters,
in Observational Cosmology, ASP Conference
Series 51, G. Chincarini et al, eds., Astron.
Society Pacific, p. 225, 1993.

Dressier, A., A. Oemler, Jr., H. R. Butcher,
and J. E. Gunn, The morphology of distant
cluster galaxies. I. HST observations of CL
0939+4713, Astrophys. J. 430, 107, 1994.

Dressier, A., A. Oemler, Jr., W. B. Sparks,
and R. A. Lucas, New images of the dis-
tant, rich cluster CL0939+4713 with
WFPC-2, Astrophys. }. Lett., in press.

Drukier, G. A., G. G. Fahlman, H. B.

Richer, L. Searle, and I. Thompson, Star
counts in NGC 6397, Astron. J. 106, 2335,
1993.

Eisenhardt, P., N. Lu, R. Elston, and P.
McCarthy, Rest frame optical spectros-
copy of distant radio galaxies, in Infrared
Astronomy with Arrays: The Next Genera-
tion, I. S. McLean, ed., Kluwer, Dordrecht,
p. 543, 1994.

Elston, R., P. J. McCarthy, P. Eisenhardt,
M. Dickinson, H. Spinrad, B. T Jannuzi,
and P. Maloney, The Seyfert II nature of
the IRAS source FSC 10214+4724, Astron.
}. 207,910,1994.

Faber, S., S. Courteau, A. Dekel, A.
Dressier, T. Kolatt, J. Willick, and A.
Yahil, Peculiar motions of galaxies and
cosmic velocity flows, /. Roy. Astron. Soc.
Canada 88 (2), 92, 1994.

Federspiel, M., A. Sandage, and G. A.
Tammann, Bias properties of extragalacric
distance indicators. III. Analysis of Tully-
Fisher distances for the Mathewson-Ford-
Buchhorn sample of 1355 galaxies,
Astrophys. J. 430, 29, 1994.

Freedman, W. L., The Local Group as
stepping stone to the universe, in The Local
Group: Comparative and Global Properties,
Third CTIO/ESO Workshop, A. Layden, C.
Smith, and J. Storm, eds., European
Southern Observatory, in press.

Freedman, W. L., and B. F. Madore,
Recent improvements to the Cepheid dis-
tance scale, in New Perspectives on Stellar
Pulsation and Pulsating Variable Stars, IAU
Colloquium 139, J. M. Nemec and J. M.
Matthews, eds., Cambridge University
Press, p. 61, 1993.

Freedman, W. L., with R. Hill et al, Hub-
ble Space Telescope first observations of
the brightest stars in the Virgo galaxy
M100 = NGC 4321, Astrophys. }. Lett., in
press.

Freedman, W. L., with M. G. Lee, R. Hill,
et al, The Hubble Space Telescope ex-
tragalactic distance scale key project. I.
The discovery of Cepheids and a new dis-
tance to M81, Astrophys. J. 427, 628, 1994.

Hill, R. J., B. E Madore, and W. L. Freed-
man, The initial mass function for massive
stars in the Magellanic Clouds. I. UBV
photometry and color-magnitude dia-
grams for 14 OB associations, Astrophys. }.
Supp. 92,583,1994.

Hill, R. J., B. F Madore, and W. L. Freed-

THE OBSERVATORIES

149

man, The initial mass function for massive
stars in the Magellanic Clouds. II. Inter-
stellar reddening toward 14 OB associa-
tions, Astrophys. J. 429, 192, 1994.

Hill, R. J., B. F. Madore, and W. L. Freed-
man, The initial mass function for massive
stars in the Magellanic Clouds. III.
Luminosity and mass functions for 14 OB
associations, Astrophys. }. 429, 204, 1994.

Hughes, S. M. G., with R. Hill, W. L.
Freedman, et al., The Hubble Space Tele-
scope extragalactic distance scale key
project. II. photometry of WFC images of
M81, Astrophys. ]. 428, 143, 1994.

Ivanov, G. R., W. L. Freedman, and B. F.
Madore, A catalog of blue and red super-
giants in M33, Astrophys. J. Supp. 89, 85,
1993.

Jun, X., A. P. S. Crotts, W. E. Kunkel, Two
new light echo structures from SN1987A
at large distances, Astrophys. /., in press.

Kaluzny, J., and W. Krzeminski, Contact
binaries and SX Phe variables in the
globular cluster NGC 4372, MNRAS 264,
785, 1993.

Kapahi, V. K., R M. Athreya, C. R. Sub-
rahmanya, R. W. Hunstead, J. C. Baker, P.
J. McCarthy, and W. van Breugel, Cos-
mological evolution of linear sizes and the
unification of quasars and radio galaxies,
in Proceedings of the IAU Asian Pacific
Regional Meeting on Astronomy, Journal of
Astrophysics and Astronomy, Indian
Academy of Sciences, Bangalore, in press.

Kennicutt, R. C, Jr., M. S. Oey, D. Zarit-
sky, and J. Huchra, Systematics of H II
region abundances in galaxies, Revista
Mexicana de Astronomia y Astrofisica 27, 21,
1994.

Koo, D. C, M. A. Bershady, G. D. Wirth,
S. A. Stanford, and S. R. Majewski, HST
images of very compact blue galaxies at z
~ 0.2, Astrophys. }. Lett. 427, L9, 1994.

Kubiak, M., and W. Krzeminski, Short
period radial velocity variations of KO
Velorum, Acta Astron. 44, 81, 1994.

Kunkel, W. E., S. Demers, and M. J.
Irwin, in The Local Group: Comparative and
Global Properties, Third CTIO/ESO
Workshop, A. Layden, C. Smith, and J.
Storm, eds. European Southern Obser-
vatory, in press.

Lee, M. G., W. L. Freedman, and B. F.
Madore, I-band Cepheid distance to NGC
6822, in New Perspectives on Stellar Pulsa-
tion and Pulsating Variable Stars, IAU Collo-
quium 139, J. M. Nemec and J. M. Mat-
thews, eds., Cambridge University Press,
p. 91, 1993.

Lee, M. G., W. L. Freedman, and B. F.

Madore, I-band Cepheid distance to
WLM, in Nezv Perspectives on Stellar Pulsa-
tion and Pulsating Variable Stars, IAU Collo-
quium 139, J. M. Nemec and J. M. Mat-
thews, eds., Cambridge University Press,
p. 92, 1993.

Lee, M. G., W. L. Freedman, and B. F.
Madore, The tip of the red giant branch as
a distance indicator for resolved galaxies,
Astrophys. J. 41 7, 553, 1993.

Lorrimer, S. J., C. S. Frenk, R. M. Smith,
S. D. M. White, and D. Zaritsky, The dis-
tribution of satellite galaxies, MNRAS
296, 696, 1994.

Madore, B. E, W. L. Freedman, and M. G.
Lee, Resolved stars in nearby galaxies:
ground-based photometry of M81,
Astron. J. 106, 2243, 1993.

Majewski, S. R., Astrometry and galactic
structure, in Astronomy from Wide Field Im-
aging, IAU Symposium 161, H. T. Mac-
Gillivray et al., eds., Kluwer, Dordrecht, p.
425, 1994.

Majewski, S. R., The Fornax-Leo-Scul-
ptor stream revisited, Astrophys. J. Lett.
431, L17, 1994.

Majewski, S. R., R. G. Kron, and D. C.
Koo, Deep UBVRI photometric calibra-
tion of high latitude fields: SA57
(1307+30) and Hercules (1720+50), Publ.
Astron. Soc. Pac, in press.

Majewski, S. R., J. A. Munn, and S. L.
Hawley, Absolute proper motions to B ~
22.5: evidence for kinematical substruc-
ture in halo field stars, Astrophys. J. Lett.
427, L37, 1994.

Mateo, M., Photometrically variable
blue stragglers, in Blue Stragglers, ASP
Conference Series 53, R. A. Saffer, ed.,
Astron. Society Pacific, p. 74, 1993.

Mazur, B., J. Kaluzny, and W. Krze-
minski, Photometric study of the inter-
mediate-age open cluster Be33, MNRAS
265, 405, 1993.

Mazur, B., W. Krzeminski, and J. Kaluz-
ny, Discovery of 45 short-period eclipsing
binaries in the field of the old open cluster
Cr261, MNRAS, in press.

McCarthy, P. J., Emission line properties
of 3CR radio galaxies. I: Imaging data,
Astrophys. J. Supp., in press.

McCarthy, P. J., and S. Persson, Energy
distributions of distant radio galaxies, in
Infrared Astronomy with Arrays: The Next
Generation, I. S. McLean, ed., Kluwer, Dor-
drecht, p. 141, 1994.

McWilliam, A., and R. M. Rich, The first
detailed abundance analysis of Galactic
bulge K giants in Baade's Window,
Astrophys. J. Supp. 91, 749, 1994.

150

CARNEGIE INSTITUTION

Miralles, M. P., L. F. Rodriguez, M. Tapia,
M. Roth, P. Persi, M. Ferrari-Toniolo, and
S. Curiel, VLA observations of Cyg OB2
No. 5: detection of a weak radio com-
panion and new observations and models
for the main component, Astron.
Astrophys. 282, 547, 1994.

Morris, S. L., R. J. Weymann, A. Dressier,
P. J. McCarthy, B. A. Smith, R. J. Terrile, R.
Giovanelli, and M. Irwin, The environ-
ment of Lyman- absorbers in the sight line
toward 3C 273, Astrophys. J. 429, 524, 1993.

Murphy, D. C, Two Offner-based IR
camera optical designs, in Infrared
Astronomy with Arrays: The Next Genera-
tion, I. S. McLean, ed., Kluwer, Dordrecht,
p. 301, 1994.

Nadeau, D., D. C. Murphy, R. Doyon,
and N. Rowlands, The Montreal near-in-
frared camera, Publ. Astron. Soc. Vac. 106,
909, 1994.

Paczynski, B., K. Z. Stanek, A. Udalski,
M. Szymanski, J. Kaluzny, M. Kubiak, M.
Mateo, and W. Krzeminski, Are the OGLE
microlenses in the Galactic bar?,
Astrophys. J. Lett., in press.

Persi, P., M. Roth, M. Tapia, M. Ferrari-
Toniolo, and A. R. Marenzi, The young
stellar population associated with the H II
region NGC 3576, Astron. Astrophys. 282,
474, 1994.

Peterson, B. M., with R. J. Weymann et
al., Steps toward determination of the size
and structure of the broad-line region in
active galactic nuclei. VII. Variability of
the optical spectrum of NGC 5548 over 4
years, Astrophys. J. 425, 622, 1994.

Petitjean, P., M. Rauch, and R. F.
Carswell, The zai,s ~ zm ~ 2 QSO absorp-
tion line systems: evidence for solar abun-
dances, Astron. Astrophys., in press.

Preston, G. W., The globular cluster and
horizontal branch content of the bulge and
halo, in Galactic Bulges, IAU Symposium
153, H. B. Dejonghe and H. J. Habing, eds.,
Kluwer, Dordrecht, p. 101, 1993.

Preston, G. W., CS 22873-139: a very
metal-poor main sequence spectroscopic
binary with colors indicative of inter-
mediate age, Astron. J., in press.

Preston, G. W., T C. Beers, and S. A.
Shectman, The space density and kine-
matics of blue metal-poor main sequence
stars near the solar circle, Astron. J. 108,
538, 1994.

Rauch, M., High resolution studies of the
Lyman alpha forest, in Proceedings of the
ESO Workshop on Science with the VLT,
Munich, June 1994, Springer-Verlag, Ber-
lin, in press.

Rauch, M., A cosmic reference frame:
using QSO absorption lines to trace the
Hubble flow, in Proceedings of the 35th
Herstmonceux Conference on Wide Field
Spectroscopy and the Distant Universe,
Cambridge, July 1994, World Scientific, Sin-
gapore, in press.

Rauch, M., A cosmic rest frame at high
redshift, MNRAS, in press.

Reid, I. N., and W. L. Freedman, The RR
Lyrae population of the LMC-I. The im-
mediate environment of NGC 2210,
MNRAS 267, 821, 1994.

Reid, N., and S. R. Majewski, Deep
multi-color starcounts, in Astronomy from
Wide Field Imaging, IAU Symposium 161, H.
T. MacGillivray et ah, eds., Kluwer, Dor-
drecht, p. 423, 1994.

Rix, H., and D. Zaritsky, The mass den-
sity amplitude of spiral arms, in Infrared
Astronomy with Arrays: The Next Genera-
tion, Kluwer, Dordrecht, p. 151, 1994.

Roth, M., The Magellan Project: A 6.5-
meter telescope at Las Campanas Obser-
vatory, Proceedings of the VII Latin Amer-
ican IAU Meeting, Vina del Mar, November
1992, Revista Mexicana de Astronomia y
Astrofisica 26, 79, 1993.

Roth, M., M. Tapia, R. Vazquez, and A.
Feinstein, JHK imaging photometry of the
Eta Carinae region, Revista Mexicana de
Astronomia y Astrofisica, in press.

Saglia, R. P., R. Bender, and A. Dressier,
The intrinsic shape of early-type galaxies
and the scatter around the fundamental
plane, Astron. Astrophys. 279, 75, 1993.

Saha, A., L. Labhardt, H. Schwengeler, F.
D. Macchetto, N. Panagia, A. Sandage,
and G. A. Tammann, Discovery of
Cepheids in IC 4182: absolute peak bright-
ness of SN la 1937C and the value of H0,
Astrophys. J. 425, 14, 1994.

Saha, A., A. Sandage, L. Labhardt, H.
Schwengeler, G. A. Tammann, N. Panagia,
and F. D. Macchetto, Discovery of
Cepheids in NGC 5253: absolute peak
brightness of SNe la 1895B and 1972E and
the value of H0, Astrophys. /., in press.

Sandage, A., The Oosterhoff period ef-
fect and the age of the Galactic globular
cluster systems, in New Perspectives on
Stellar Pulsation and Pulsating Variable
Stars, IAU Colloquium 139, J. M. Nemec
and J. M. Matthews, eds., Cambridge
University Press, p. 3, 1993.

Sandage, A., The cosmological para-
meters H0, Q, A, in Observational Cosmol-
ogy, ASP Conference Series 51, G. Chin-
carini et ah, eds., Astron. Society Pacific, p.
3, 1993.

Pintle bearing being prepared at L&F Industries, Huntington Park, California, for the Magellan
telescope, July 1994. The pintle bearing will sit on the concrete foundation below the telescope,
and will serve as the bearing, drive, and encoding surface for the telescope's azimuth rotation.

Sandage, A., Bias properties of extragal-
actic distance indicators. I. The Hubble
constant does not increase outward,
Astrophys. J. 430, 1, 1994.

Sandage, A., Bias properties of ex-
tragalactic distance indicators. II. Bias cor-
rections to Tully-Fisher distances for field
galaxies, Astrophys. J. 430, 13, 1994.

Sandage, A., R. Diethelm, and G. A. Tam-
mann, The P-L relation for RR Lyrae-like
stars with 0.8d< P< 3d, Astron. Astrophys.
283,111,1994.

Sandage, A., A. Saha, G. A. Tammann, L.
Labhardt, H. Schwengeler, N. Panagia,
and F. D. Macchetto, The Cepheid dis-
tance to NGC 5253: calibration of M(max)
for the Type I supernovae SN 1972E and
SN 1895B, Astrophys. J. Lett. 423, L13, 1994.

Sandage, A., Introduction to the reprint
edition of Explorer of the Universe: A Biog-
raphy of George Ellery Hale, by Helen
Wright, American Institute of Physics,
New York, 1994.

Schechter, P. L., M. Mateo, and A. Saha,
DoPHOT, A CCD photometry program:
description and tests, Pnbl. Astron. Soc.
Pac. 105, 1342, 1993.

Shectman, S., The optical design of the
Magellan Project 6.5-meter telescope, in
Advanced Technology Optical Telescopes V,
L. M. Stepp, ed., SPIE, Bellingham,
Washington, p. 558, 1994.

Sivaramakrishnan, A., R. J. Weymann,
and J. W. Beletic, Measurements of the
angular correlation of stellar centroid mo-
tion, in Proceedings of the ICO-16 Satellite
Conference on Active and Adaptive Optics,
ESO Conference and Workshop Proceedings
No. 48, F. Merkle, ed., European Southern
Observatory, p. 9, 1994.

Sneden, C., G. W. Preston, A. McWilliam,

and L. Searle, Ultrametal-poor halo stars:
the remarkable spectrum of CS 22872-052,
Astrophys. }. Lett 431, L27, 1994.

Suntzeff, N. B., M. Mateo, D. M. Tern-
drup, E. W. Olszewski, D. Geisler, and W.
Weller, Spectroscopy of giants in the Sex-
tans dwarf spheroidal galaxy, Astrophys. J.
418,208,1993.

Szymanski, M., A. Udalski, J. Kaluzny,
M. Kubiak, M. Mateo, W. Krzeminski, G.
W Preston, and B. Paczynski, The optical
gravitational lensing experiment — first
data, in Gravitational Lenses in the Universe:
Proceedings of the 31st Liege International
Astrophysical Colloquium, June 21-25, 1993,
J. Surdej, ed., Universite de Liege, Institut
d'Astrophysique, Liege, 1993.

Tapia, M., M. Roth, R. Vazquez, A. Fein-
stein, and P. Prado, UBVRI imaging
photometry of the Carina region, Revista
Mexicana de Astronomia y Astrofisica, in
press.

Testi, L., M. Felli, P. Persi, and M. Roth,
Near infrared images of Galactic masers:
I. Association between infrared sources
and masers, Astron. Astrophys., in press.

Tremaine, S., D. O. Richstone, Y. Byun, A.
Dressier, S. M. Faber, C. Grillmair, J. Kor-
mendy, and T. R. Lauer, A family of
models for spherical stellar systems,
Astron. f. 107, 634, 1994.

Trevese, D., R. G. Kron, D. C. Koo, S. R.
Majewski, and M. A. Bershady, The en-
semble variability properties of faint
quasars, Astrophys. }., in press.

Turnshek, D. A., with M. Rauch and R. J.
Weymann, The HST quasar absorption
line key project. IV. HST faint object
spectrograph and ground-based observa-
tions of the unusual low-redshift broad
absorption line quasi-stellar object PG

152

CARNEGIE INSTITUTION

0043+039, Astrophys. J. 428, 93, 1994.

Udalski, A., M. Szymanski, J. Kaluzny,
M. Kubiak, W. Krzeminski, M. Mateo, G.
W. Preston, and B. Paczynski, The optical
gravitational lensing experiment. Dis-
covery of the first candidate microlensing
event in the direction of the Galactic
bulge, Acta Astron. 43, 289, 1993.

Udalski, A., M. Szymanski, J. Kaluzny,
M. Kubiak, M. Mateo, and W. Krzeminski,
The optical gravitational lensing experi-
ment. The discovery of three further
microlensing events in the direction of the
Galactic bulge, Astrophys. J. Lett. 426, L69,
1994.

Udalski, A., M. Szymanski, J. Kaluzny,
M. Kubiak, M. Mateo, G. W. Preston, W.
Krzeminski, K. Z. Stanek, and B. Pac-
zynski, The Warsaw-Carnegie-Princeton
optical gravitational lens experiment, in
Texas/PASCOS '92: Relativistic Astrophysics
and Particle Cosmology, Annals of the New
York Academy of Sciences 688, C. W. Akerlof
and M. A. Srednicki, eds., New York
Academy of Sciences, p. 626, 1993.

Udalski, A., M. Szymanski, J. Kaluzny,
M. Kubiak, M. Mateo, G. Preston, W.
Krzeminski, and B. Paczynski, Microlens-
ing towards the Galactic bulge, in Galactic
Bulges, IAU Symposium 153, H. B. Dejon-
ghe and H. J. Habing, eds., Kluwer,
Dordrecht, p. 311, 1993.

Udalski, A., M. Szymanski, K. Z. Stanek,
J. Kaluzny, M. Kubiak, M. Mateo, W.
Krzeminski, B. Paczynski, and R. Venkat,
The optical gravitational lensing experi-
ment. The optical depth to gravitational
microlensing in the direction of the Galac-
tic bulge, Acta Astron. 44, 165, 1994.

Voit, G. M., M. Donahue, and J. D. Slavin,
Emission lines from condensing in-
tracluster gas, Astrophys. J. Supp., in press.

Welch, D. L., M. Mateo, and E. Olszew-
ski, Cepheids in Magellanic Cloud
clusters, in New Perspectives on Stellar Pul-
sation and Pulsating Variable Stars, IAU Col-
loquium 139, J. M. Nemec and J. M. Mat-
thews, eds., Cambridge University Press,
p. 359, 1993.

Weymann, R. J., Properties of the Lyman
alpha forest at high and low redshifts, in
The Environment and Evolution of Galaxies:
Proceedings of the Third Teton Summer
School held in Grand Teton National Park,
Wyoming, U.S.A., July 1992, H. Thronson
and J. M. Shull, eds., Kluwer, Dordrecht,
p. 213, 1993.

Weymann, R. J., M. Rauch, R. Williams,
S. Morris, and S. Heap, New observations
with the HST Goddard High Resolution

Spectrograph of the low redshift Ly
clouds in the 3C273 line of sight,
Astrophys. J., in press.

Willick, J. A., Statistical bias in distance
and peculiar velocity estimation. I. The
"calibration" problem, Astrophys. J. Supp.
92, 1, 1994.

Zabludoff, A. I., and M. Franx, Morphol-
ogy and kinematics in clusters of galaxies,
in Galaxy Clusters and Large-Scale Struc-
tures in the Universe, Proceedings of the Sesto
International Workshop (SISSA preprint ref.
86/93/ A), 1993.

Zabludoff, A. I., M. Franx, and M. J.
Geller, A technique for detecting structure
in cluster velocity distributions,
Astrophys. J. 419, 47, 1993.

Zabludoff, A. I., and M. J. Geller, The
kinematics of dense clusters of galaxies.
III. Comparison with cosmological
models, Astron. J. 107, 1929, 1994.

Zaritsky, D., Comments on the distribu-
tion of mass within dark matter halos,
STScI Workshop on Groups of Galaxies, O.
Richter, ed., in press.

Zaritsky, D., Gravitationally bound com-
panion galaxies, in Proceedings of the
ESO/OHP Dwarf Galaxy Meeting, G.
Meylan, ed., European Southern Obser-
vatory, in press.

Zaritsky, D., Local Group dynamics, in
The Local Group: Comparative and Global
Properties, Third CTIO/ESO Workshop, A.
Layden, C. Smith, and J. Storm, eds.,
European Southern Observatory, in press.

Zaritsky, D., Preliminary evidence for
dust in galactic halos, Astron. J., in press.

Zaritsky, D., J. R. C. Kennicutt, and J. P.
Huchra, H II regions and the abundance
properties of spiral galaxies, Astrophys. J.
420, 87, 1994.

Zaritsky, D., M. Rieke, and H. Rix, IR
imaging of spiral galaxy bulges, in Galac-
tic Bulges, IAU Symposium 153, H. B.
Dejonghe and H. J. Habing, eds., Kluwer,
Dordrecht, p. 441, 1993.

Zaritsky, D., and H. Rix, The shapes of
spiral galaxy disks, in Infrared Astronomy
with Arrays: The Next Generation, I. S. Mc-
Lean, ed., Kluwer, Dordrecht, p. 457, 1994.

Zaritsky, D., and S. D. M. White, Satellite
galaxies as dark matter probes, in Proceed-
ings of the ESO/OHP Dwarf Galaxy Meeting,
G. Meylan, ed., European Southern Ob-
servatory, in press.

Zaritsky, D., and S. D. M. White, The
massive halos of spiral galaxies,
Astrophys. J., in press.

THE OBSERVATORIES

153

Personnel

Research Staff

Horace Babcock, Emeritus
Alan Dressier
Wendy Freed man
Jerome Kristian
Patrick McCarthy1
Eric Persson
George Preston
Allan Sandage
Leonard Searle, Director
Stephen Shectman
Ian Thompson
Ray Weymann

Staff Associates

Steve Majewski, Hubble Fellow

Postdoctoral Fellows and Associates

Megan Donahue, Carnegie Fellow2
Bob Hill, Research Associate
Stephen Landy, Research Associate3
Andrew Mc William, McClintock Fellow
Michael Rauch, Research Associate
Jeffrey Willick, Carnegie Fellow
Ann Zabludoff, Carnegie Fellow
Dennis Zaritsky, Hubble Fellow

Las Campanas Research Staff

Wojciech Krzeminski, Resident Scientist
William Kunkel, Resident Scientist
Miguel Roth, Director, Las Campanas
Observatory

Support Scientists

William Kells

David Murphy

Anand Sivaramakrishnan

Supporting Staff, Pasadena

Alan Bagish, Las Campanas Observatory

Engineer4
Richard Black, Business Manager
David Carr, Magellan Project Instrument

Engineer
Ken Clardy, Data Systems Manager
Marinus de Jonge, Magellan Project

Manager5
Joseph Dizon, Instrument Maker
Elizabeth Doubleday, Publications Editor

Joan Gantz, Librarian
Bronagh Glaser, Administrative Assistant6
Karen Gross, Assistant to the Director
Matt Johns, Magellan Project Systems

Engineer7
Roberto Mejia, Housekeeper8
Kristin Miller, Magellan Project

Administrative Assistant
Stephen Padilla, Photographer
Gloria Pendlay, Administrative Assistant
Frank Perez, Magellan Project Lead Engineer
Melissa Pratt, Administrative Assistant^
Pilar Ramirez, Machine Shop Foreperson
Lorraine Renfroe, Staff Accountant
Scott Rubel, Assistant, Buildings and

Grounds
Jeanette Stone, Purchasing Agent10
Robert Storts, Instrument Maker
Estuardo Vasquez, Instrument Maker
Steven Wilson, Superintendent, Buildings

and Grounds

Supporting Staff Las Campanas

Eusebio Araya, Mountain Superintendent

Juan Araya, Part-time El Pino Guard11

Hector Balbontin, Chef

Emilio Cerda, Electronics Technician

Angel Cortes, Accountant

Jose Cortes, Janitor

Jorge Cuadra, Assistant Mechanic12

Oscar Duhalde, Mechanical Technician

Julio Egaha, Painter

Gaston Figueroa, Small Shift Supervisor13

Luis Gallardo, El Pino Guard14

Juan Godoy, Chef

Jaime Gomez, Purchasing Agent

Danilo Gonzalez, El Pino Guard

Bruno Guerrero, Electronic Technician

Luis Gutierrez, Mechanic

Javier Gutierrez, Heavy Equipment Operator

Juan Jeraldo, Chef

Leonel Lillo, Carpenter

Mario Mondaca, Part-time El Pino Guard

Cesar Muena, Night Assistant

Silvia Munoz, Business Manager

Herman Olivares, Night Assistant

Fernando Peralta, Night Assistant

Leonardo Peralta, Driver /Purchaser

Roberto Ramos, Gardener

Demesio Riquelme, Janitor15

Jose Rodriguez, Welder16

Honorio Rojas, Water Pump Operator

Hernan Solis, Electronics Technician

Mario Taquias, Plumber

154

CARNEGIE INSTITUTION

Alejandro Tirado, Warehouse Attendant17
Gabriel Tolmo, El Pino Guard
Manuel Traslavina, Heavy Equipment

Operator
David Trigo, Warehouse Attendant18
Patricia Villar, Administrative Assistant
Alberto Zuhiga, Night Assistant

Visiting Investigators

Gonsalo Alcaino, Instituto Isaac Newton,

Chile
Ramana Athreya, Giant Meter- Wave Radio

Telescope, Poona University, Pune, India
Rebecca Bernstein, California Institute of

Technology
Leonardo Bronfman, Universidad de Chile
Joe Cantanzarite, Cypress College, NASA

JOVE Associate
George Carlson, Citrus College
Bob Carswell, Institute of Astronomy,

University of Cambridge
Wen Ping Chen, Department of Terrestrial

Magnetism
Patrick Cote, McMaster University
Stephen Eikenberry, Harvard University
Greg Fahlman, University of British

Columbia
Max Faundez-Abans, Universidad Catolica

de Chile
Giovanni Fazio, Harvard University
Jay Frogel, Ohio State University
Wolfgang Gieren, Universidad Catolica de

Chile
John Graham, Department of Terrestrial

Magnetism
Richard Griffith, Arizona State University
Paul Harding, University of Arizona
Leopoldo Infante, Universidad Catolica de

Chile
Vijay Kapahi, Giant Meter- Wave Radio

Telescope, Poona University, Pune, India
Nobu-nari Kashikawa, National

Astronomical Observatory, Tokyo, Japan
Martien Kubiak, Warsaw University

Arlo Landolt, Louisiana State University
William Liller, Instituto Isaac Newton, Chile
Huan Lin, Harvard University
Barry Madore, California Institute of

Technology
Mario Mateo, University of Michigan
Jose Maza, Universidad de Chile
John Middleditch, Los Alamos National

Laboratory
Jeremy Mould, California Institute of

Technology
Steve Mutz, Arizona State University
Edward Olszewski, University of Arizona
Michael Pahre, California Institute of

Technology
Patrick Petirjean, Institute of Astrophysics,

Paris
Hernan Quintana, Universidad Catolica de

Chile
Neill Reid, California Institute of Technology
Hans- Walter Rix, Princeton University
Monica Rubio, Universidad de Chile
Maria Teresa Ruiz, Universidad de Chile
Paul Schechter, Massachusetts Institute of

Technology
Paul Schmidke, Arizona State University
Nicholas Schneider, University of Colorado
Maki Sekiguchi, National Astronomical

Observatory, Tokyo, Japan
Michael Shara, Space Telescope Science

Institute
Adam Standford, Jet Propulsion Laboratory,

California Institute of Technology
John Trauger, Jet Propulsion Laboratory,

California Institute of Technology
Andrzej Udalski, Warsaw University
Michal Szymanski, Warsaw University
Alan Uomoto, Johns Hopkins University
Patricia Vader, Space Telescope Science

Institute
Wil van Breugel, Lawrence Livermore

National Laboratory
Rogier Windhorst, Arizona State University
Masafumi Yagi, National Astronomical

Observatory, Tokyo, Japan

Trom September 1, 1993
2To August 31, 1993
3From September 1, 1993
4From May 24, 1993
5From August 1, 1993
6From August 18, 1993
7From July 1, 1994
8From April 16, 1994
9To March 19, 1994

10FromJunel, 1994
nTo June 30, 1993
12From August 2, 1993
13From April 18, 1994
14FromJuly 1,1993
15FromJuly3,1993
16To September 17, 1993
17To August 20, 1993
18From May 6, 1993

EXTRADEPARTMENTAL AND

Adminis TRATIVE

Saturday morning at First Light

Personnel

Members of the Departments are
listed in the preceding sections.

Office of Administration
1530 P Street, N.W.
Washington, D.C. 20005

Lloyd Allen, Building Maintenance Specialist
Sharon Bassin, Secretary to the President
Sherrill Berger, Research Assistant,

Institutional and External Affairs
Ray Bowers, Editor and Publications Officer
Gloria Brienza, Budget and Management

Analysis Manager
Don A. Brooks, Building Maintenance

Specialist
Cady Canapp, Human Resources and

Insurance Manager
Margaret Charles, Secretary
Ines Cifuentes, Program Coordinator,

Carnegie Academy for Science Education
Patricia Craig, Associate Editor
Linda Feinberg, Editorial /Administrative

Assistant
Susanne Garvey, Director of Institutional and

External Affairs
Mary Ann Kaschalk, Financial Accountant
Ann Keyes, Accounts Payable /Payroll

Coordinator
John J. Lively, Director of Administration and

Finance
Lynn Morrow, Grants and Operations

Manager

Trong Nguyen, General Accountant
Danielle Palermo, Administrative Assistant,

Grants and Operations
Loretta Parker-Brown, Administrative

Secretary1
Catherine Piez, Systems and Fiscal Manager
Arona Primalani, Systems Intern2
Arnold J. Pryor, Facilities and Services

Supervisor
Lisa Schubert, Financial Manager3
Maxine F. Singer, President
John Strom, Administrative Support Assistant
Kris Sundback, Financial Manager4
Vicki Tucker, Administrative Coordinator,

Accounts Payable
Ernest Turner, Custodian (on call)5
Susan Y. Vasquez, Assistant to the President
Yulonda White, Human Resources and

Insurance Records Coordinator
Jacqueline J. Williams, Assistant to Manager,

Human Resources and Insurance

1 From November 15, 1993

2 From February 8, 1994

3 To August 31, 1993

4 From September 13, 1993

5 From October 1, 1993

157

Publications

Publications of The Institution

Carnegie Institution of Washington Year Book 92, viii
+ 200 pages, 67 illustrations, December 1993.

Spectra: The Newsletter of the Carnegie Institution,
issued in November 1993, April 1994, June
1994, special Las Campanas/Magellan issue,
March 1994.

Carnegie Institution of Washington, informational
booklet, 24 pages, 20 illustrations, August 1993.

Carnegie Evening 1994, 8 pages, 4 illustrations,
May 1994.

This Our Golden Age: Selected Annual Essays of
Caryl P. Haskins, James D. Ebert, ed., x + 141
pages, 10 illustrations, May 1994.

Publications of The President

McMillan, J. P., and M. F. Singer, Studies on the
translation of the two open reading frames of
the human LINE-1 element, LIHs, Proc. Natl.
Acad. Sci. USA 90, 11533-11537, 1993.

Singer, M. R, V. Krek, J. P. McMillan, G. D.
Swergold, and R. E. Thayer, LINE-1: a human
transposable element, Gene 135, 183-188, 1993.

Thayer, R. E., M. F. Singer, and T. G. Fanning,
Undermethylation of specific LINE-1
sequences in human cells producing a
LINE-1-encoded protein, Gene 133, 273-277,
1993.

Singer, M. F., From genomic junk to human
disease, Proc. Amer. Philos. Soc. 138, no. 1,
11-42, 1994.

Singer, M. E, The freedom and optimism that
drive science sound like rather admirable
attributes, in The Challenge of Heritage,
Brombergs, ed., 206-217, 1993.

Singer, Maxine, No, you can't make dinosaurs,
Washington Post, July 7, 1993; Hot tomato,
Washington Post, August 10, 1993.

Singer, Maxine, and Paul Berg, Geni e Genomi, D.
Conti, tr., Zanichelli, Bologna, 1993 (Italian
edition).

Singer, Maxine, and Paul Berg, Genes & Genomes,
K. Arai and Hisao Masai, tr., Tokyo Kagaku
Dogin, Inc., Tokyo, 1994 (Japanese edition, in 2
vols.).

Berg, Paul, and Maxine Singer, Die Sprache der
Gene: Grundlagen der Molekulargenetik, S. Vogel,
tr., Spektrum, Heidelberg, 1993 (German
edition of Dealing with Genes).

Berg, Paul, and Maxine Singer, Tratar con genes: El
Lenguaje de la Herencia, L. Luis Ruiz-Avila, tr.,
Omega, Barcelona, 1994 (Spanish edition of
Dealing with Genes).

Berg, Paul, and Maxine Singer, Comprendre et
maitriser les genes: le langage de Vheredite, N.
Glansdorff, tr., Vigot, Paris, 1993 (French
edition of Dealing with Genes).

Berg, Paul, and Maxine Singer, Basic Molecular
Genetics, H. Okayama, A. Nagata, T.
Nishimura, S. Kamino, and K. Sudo, tr., Tokyo
Kagaku Dogin, Inc., Tokyo, 1994 (Japanese
edition of Dealing with Genes).

158

Special Events

Capital Science Lecture Series

Thomas E. Lovejoy, Mapping the Nation
Biologically, October 19, 1993.

Sean C. Solomon, Venus and Mars, or Why Can't
a Planet Be More Like an Earth?, November 16,
1992.

Lucy Shapiro, From Egg to Elephant: Directed
Cell Differentiation, December 7, 1993.

Ralph E. Gomory, Science, Technology, and
Government, January 18, 1994.

Jacqueline K. Barton, Travels Along the DNA
Helix, February 8, 1994.

Judith Rodin, Aging, Control, and Health, March
1, 1994.

James Gleick, Scientists v. Journalists, April 5,
1994.

Francis S. Collins, The Human Genome Project,
May 17, 1994.

Carnegie Evening Lecture

Robert E. Kohler, Partners in Science: Foundations
and Scientists, May 5, 1994.

159

Report of the Executive Committee

To the Trustees of the Carnegie Institution of Washington

In accordance with the provisions of the By-Laws, the Executive Committee
submits this report to the Annual Meeting of the Board of Trustees.

During the fiscal year ending June 30, 1994, the Executive Committee has
held four meetings. Accounts of these meetings have been or will be mailed to
each Trustee.

A full statement of the finances and work of the Institution for the fiscal
year ended June 30, 1993 appears in the Institution's Year Book 92, a copy of
which has been sent to each Trustee. An estimate of the Institution's
expenditures in the fiscal year ending June 30, 1995 appears in the budget
recommended by the Committee for approval by the Board of Trustees.

The terms of the following members of the Board expire on May 6, 1994:

William T. Coleman, Jr. Gerald D. Laubach

Edward E. David, Jr. Sally K. Ride

Richard E. Heckert Robert C. Seamans, Jr.

Antonia Ax:son Johnson David F. Swensen

A vacancy exists in the membership of the Executive Committee for a term
ending in 1995, resulting from the resignation of Gerald D. Laubach as a
member of the Committee.

In addition, the terms of the Vice-Chairman of the Board, all Committee
Chairmen, and the following members of the Committees expire on May 6,
1994:

Finance Committee Auditing Committee

William T. Golden Philip H. Abelson

Nominating Committee
Richard A. Meserve

William I. M. Turner, Jr., Chairman
May 6, 1994

161

Abstract of Minutes

of the One Hundreth Meeting of the Board of Trustees

The Annual Meeting of the Board of Trustees was held in the
Board Room of the Administration Building on Friday, May 6, 1994.
The Meeting was called to order by the Chairman, Thomas N. Urban.

The following Trustees were present: Philip H. Abelson, William T.
Coleman, Jr., John Diebold, James D. Ebert, Wallace Gary Ernst, Bruce
W. Ferguson, William T. Golden, David Greenewalt, William R. Hearst
III, Richard E. Heckert, Kenneth G. Langone, Gerald D. Laubach, John
D. Macomber, Richard A. Meserve, Robert C. Seamans, Jr., David F.
Swensen, Charles H. Townes, Thomas N. Urban, and Sidney J.
Weinberg, Jr. Also present were Caryl R Haskins and Richard S.
Perkins, Trustees Emeriti; Maxine F. Singer, President; Donald D.
Brown, Director of the Department of Embryology; Charles T. Prewitt,
Director of the Geophysical Laboratory; Sean C. Solomon, Director of
the Department of Terrestrial Magnetism; Christopher Somerville,
Director of the Department of Plant Biology; Stephen A. Shectman,
Head of the Magellan Project; Allan Spradling, Director-Designate of
the Department of Embryology; John J. Lively, Director of
Administration and Finance; Susanne Garvey, Director of Institutional
and External Affairs; Susan Y. Vasquez, Assistant Secretary; and
Marshall Hornblower, Counsel.

The minutes of the Ninety-Ninth Meeting, held at the Department
of Terrestrial Magnetism on December 16-17, 1993, were approved.

The Chairman notified the Trustees of the death of Crawford H.
Greenewalt. He read a memorial statement in tribute to Mr.
Greenewalt, and the following resolution was unanimously adopted:

Be It Therefore Resolved, That we, the Trustees of Carnegie
Institution of Washington, record our deep sense of loss at the
death of our friend and companion, Crawford Hallock Greenewalt.

And Be It Further Resolved, that this resolution be entered on the
minutes of the Board of Trustees and that copies be sent to his
family.

The reports of the Executive Committee, the Finance Committee,
the Employee Benefits Committee, and the Auditing Committee were
accepted. On the recommendation of the latter, it was resolved that

163

Price Waterhouse & Co. be appointed as public accountants for the fiscal
year ending June 30, 1994.

Section 3.5 of the By-Laws was amended. In addition, wherever they
appear in the By-Laws, the pronouns "he" and "his" were amended to
read "he or she" and "his or hers." The amended language is given in
the By-Laws printed on pages 183-188 of this year book.

On recommendation of the Nominating Committee, the following
were re-elected for terms ending in 1997: William T. Coleman, Jr.,
Edward E. David, Jr., William T. Golden, Richard E. Heckert, Gerald D.
Laubach, and David F. Swensen.

William I. M. Turner, Jr., was elected Vice-Chairman of the Board of
Trustees for a term ending in 1997. William T. Golden was elected
Secretary of the Board of Trustees for a term ending in 1997.

The following were elected for one-year terms: William I. M. Turner,
Jr., as Chairman of the Executive Committee; David F. Swensen, as
Chairman of the Finance Committee; Philip H. Abelson, as Chairman of
the Auditing Committee; and William T. Coleman, Jr., as Chairman of
the Employee Benefits Committee. Sidney J. Weinberg, Jr., was
appointed Chairman of the Nominating Committee for a one-year term.

Vacancies in the Standing Committees, with terms ending in 1997,
were filled as follows: William T. Golden was elected a member of the
Finance Committee; Philip H. Abelson was elected a member of the
Auditing Committee; and Richard A. Meserve was elected a member of
the Nominating Committee. In addition, John D. Macomber was elected
a member of the Executive Committee for the unexpired term ending in
1995.

The Chairman pointed out that Robert C. Seamans, Jr., Antonia
Ax:son Johnson, and Sally K. Ride had chosen not to stand for
re-election. These resignations were noted with regret; special
recognition was given to the 20-year active service of Dr. Seamans,
including five years as Vice-Chairman of the Board; and in accordance
with Section 1.6 of the By-Laws, Dr. Seamans was designated Trustee
Emeritus.

The annual report of the President was received.

To provide for the operation of the Institution for the fiscal year
ending June 30, 1995, and upon recommendation of the Executive
Committee, the sum of $33,571,582 was appropriated.

164

Financial Statements

for the year ended June 30, 1994

^c

nC

o\

ON

nC

cc

O

co

oc

rH

00

tx

tx

CN

lo

"

oo N co r-i Tf ro : o cn co oo cn

CO ON tN CO 0> N CN CM CN
LO CN CO (N CN i-h rH

NO o

IX T-t

od co

r-t LO

NO NO O

NO CO On

rH hh NO

^H Csl

LO CO
ON <*
LO LO
LO-

CO LO ON rH 00 'OONNhh

LX LO ON rF CN • 00 NfO Kr- 1

c© co^ co on oq_ nhmn

CN CO- CN CN rH ^h"

o

CO

>-* On s

0 ^H -«

H I ^

(J lo g

7 00 u

K On wi

< Ch —

<: < 2

►-* *h vi

Ph a ^

O 2 «

2 5 «

H tJ IS

- 2 ^

li i

W Ph ^

rn ^ £!

w < «

< 2

U w

,bp

on o no

cn rn co

O rH W

rH CN

LO CO ON
K\D ON
^h o NO

1

, i

nC

\C

LO

00

CD

no

CN

LO

""■*

CO

NO

00

nO

ON

ri

o

CO

ON

l-H

LO?

■f-A-

"-*

CN LO NO

CN rH ON

t HO0

H CO" """"'

CO IX o

00 "f ^H

lx no o

ON CN NO
N CO N
hh LO 00

^ ^D N

oo oo co

LO HH 00

H QJ

to s2i

> QJ

c .a

"S E
s &

& S

0JD 2

QJ ■£

CO

£

oJO >

c3 £

C "55

0) QJ

cy

04

Cs5

CO LO
IX LO

NO_ ON

-^ co

CN IX

ON CN
LO

ON 00
LO O

O lx

nov

CO
LO

ON ON
ON O
ON ON

ON
CO

CN
IX
LO

o

LO

CN

LO-

CN

CO

co-
co

tx

OJ

CN

t

ON

LO

NO

NO ON

HH CO

ON NO

Lx"

CN HH

NO NO

O IX

QJ

c

rc qj

Jh Xi

i! CO

qj -a

04 O

CO

ON

oo

^H

C0

: oc

ON

LOj

CO

,-H

o

LOv

NO

LO

ON

LO

OJ

LX

oj-

CO

CN

co

C^j

NO

c^

ON

ON

o

NO

: on

~*

-v

HH

OJ

CO

CO

oc

Lx

HH

■ ON

o

IX

OJ

LO)

IX

c

q

'ON

OJ

OJ

-t

OJ

Lx

OJ

-f-

oj-

HH

OJ

'-f

NO

00

CN

HH

LO

: <n

HH

lx

HH

ON

LO

X

C^i

CO

LO

o

LO

CO

IX

CO

NO

OJ

ON

X

CO

NO

OJ

CO-

OJ

-f

oj-

CO

OJ

^^

rH on

LO LO

ON ON

O

g-1 s o
3 C u

OH QJ ~H

QJ > iS

c iS 8
•2(2

Cl,

U

NvOhoOh . ^t N vO Tf( IT)

cNootxoLo ■^cj^Nin

CN O CN »-• CO ' h (N h in ro

CO- ^ CO- ^ CN rH

mcoxoH^NTf^H^

lOOOOOOCNnOnOLOLOO

HNOOHNrHMvOHlT)^
- CN H rH

H CO ^ CO HH

LOLX-HHrHONrHOOONLOOrH
ONr-ICNIXONLOCOr-I^OOOON
H N O fO \C ^ H LX rH LO CO
COV <*■ "^ ^ CN rH ^h-

HNn^ir)mO\tooH\o

OOvO^OwO^On^DNhk
rH-HHCOLOCN'HHCNCOT-lLOrO

CO "HH HH HH CO rH

CNLOOnnDCOOnnOlOOOHhcO
COOOLO^OOOCOIXCNON
ONtX^LXOOHHLOCOr-lCOCO

CO HH THH HH CO

a ■ a

ra qj

*{H CD

TJ a3 j3

m inO

QJ QJ <J

CO }H QJ

r! 'h ^h

JTl QJ rH

en p-h

QJ g

>>x -prfa

2^5^

C ij "J

o.S 5
« 2? c

O £
S CO

T3
Ch<

O

o JST3

Ph C QJ

^ .2 J5
° 55 qj

QJ W QJ

4- T3

C "3 QJ .^

E fS 04 O O £ o5

-5 g ^-.^ o

QJ

CO ^

C ^

I «

-2 QJ

(h 0JD

13

c

QJ

&'&

cx

sg

X

0J

T3 qj

C »H

"Jc

C3 o

M-H

o

en qj

^

QJ _Q

r QJ

QJ en

> C

QJ QJ

^ PH

"^j -5

oo ^

ON NO
H <*

oo- <*

LX

CN

QJ QJ

II

|§

^H ^2

166

Carnegie Institution of Washington
Financial Statements

Contributions, Gifts, and Private Grants
for the Year Ended June 30, 1994

Anonymous

Philip H. Abelson

Ahmanson Foundation

Jagannadham Akella

Rita Allen Foundation

American Cancer Society

Bennett Archambault

ARCO Foundation

AT&T Bell Laboratories

Horace W. Babcock

Hubert L. Barnes

Robert W. Bates

Giuseppe and L. Elizabeth Bertani

Blackwell Scientific Publications, Ltd.

Ellis and V. Elaine Bolton

Tom I. Bonner

Montgomery S. Bradley

Bristol-Myers Squibb Foundation, Inc.

Deborah L. Brown

Jeanette Brown

Linda W. Brown

Gordon Burley

Kenneth D. Burrhus

Donald M. Burt

Morris and Gwendolyn Cafritz Foundation

John A. R. Caldwell

Dana Carroll

Carnegie Corporation of New York

Paterno R. Castillo

Centre National de la Recherche Scientifique

Britton Chance

Jane Coffin Childs Memorial Fund for

Medical Research
Matthias Chiquet
King-chuen Chow
CIGNA Corporation
Citibank, N.A.
William T. Coleman, Jr.
John and Annette Coleman
Robert Criss
John R. Cronin
Stephen M. Cutler
Howard Clark Dalton
Edwin A. Davis
Vincent J. De Feo
John P. de Neufville
Louis and Nahid De Lanney
John and Ruth Doak
Bruce R. Doe
Jean Wallace Douglas
William N. Dove
Dudley Observatory

E. I. du Pont de Nemours & Co.

James and Alma Ebert

Eistophos Science Club

Donald Elthon

W. Gary Ernst

Sandra M. Faber

Bruce W. Ferguson

Holly K. Fine

Andrew Fire

Dorothy R. Fischer

Michael and Helen Fleischer

Flintridge Foundation

Freepost McMoran, Inc.

L. Patrick Gage

M. Charles Gilbert

Robert G. Goelet

Golden Family Foundation

Cecil and Ida Green Foundation

Crawford H. Greenewalt

Richard D. and Irene M. Grill

Helen M. Habermann

Pembroke J. Hart

Stanley R. Hart

Caryl and Edna Haskins

Robert M. Hazen

Ulrich Heber

Richard E. Heckert

H. Lawrence Heifer

Alfred D. Hershey

John L. Hess

William R. Hewlett

Hillsdale Fund, Inc.

Paul and Annetta Himmelfarb Foundation

Anne Hofmeister

Satushi Hoshina

Howard Hughes Medical Institute

Kazuo Inamori

Intl. Human Frontier Science Program

Institute for Advanced Study

Mizuho Ishida

George F. Jewett, Jr., 1965 Trust

Antonia Ax:son Johnson

Johnson & Johnson

W. M. Keck Foundation

Kristi Kendall

Olavi Kouvo

L & F Industries

Otto E. Landman

Gerald D. Laubach

Gerald D. Laubach Fund

Faith and Arthur LaVelle

Arthur Lazarus, Jr.

167

Carnegie Institution of Washington
Financial Statements

Contributions, Gifts, and Private Grants
for the Year Ended June 30, 1994 (continued)

Harold Lee

Melvyn Lieberman

Life Sciences Research Foundation

Dan L. Lindsley

Charles A. Little

Felix J. Lockman

Eric Long

Richard Lounsbery Foundation

John D. Macomber

Winston M. Manning

Mariah Associates

Lucille P. Markey Charitable Trust

Marlow Marrs

Martek Biosciences Corporation

William McChesney Martin Jr. Living Trust

Chester B. Martin

G. Harold and Leila Y. Mathers Charitable

Foundation
Robert H. McCallister
Sheila McCormick
Steven McKnight
McKnight Endowment Fund for

Neuroscience
Andrew W. Mellon Foundation
John Merck Fund

Richard A. and Martha R. Meserve
Paul F. and Ella Miller Jr.
Xenia S. and J. Irwin Miller Trust
Mobil Foundation
Ambrose Monell Foundation
Monsanto Fund
Mary Lee Morrison
Gisela Mosig
Norio Murata
Jack E. Myers

Newmont Mining Corporation
Norton Company
Garrison Norton
Yasumi Ohshima
T. S. Okada
E. F. Osborn
Jeffrey D. Palmer
George H. Pepper
Richard S. Perkins
Pfizer, Inc.

Pioneer Hi-Bred International, Inc.
Proctor & Gamble Company
George Putnam
Cary Queen

Estate of Elizabeth Ramsey Klagsbrunn
Sally K. Ride
Glenn C. Rosenquist

Vera C. Rubin

Sandoz Corporation

Ruth N. Schairer

Paul Schechter

Maarten and Corrie Schmidt

Sara Lee Schupf

Eugenia A. and Robert C. Seamans, Jr.

Martin and Marilyn Seitz

Keith Calhoun Sengour

John J. F. Sherrerd

Edwin M. Shook

David Singer

Maxine F. Singer

Alfred P. Sloan Foundation

Smithsonian Institution

Space Telescope Science Institute

SRA International, Inc.

Frank Stanton

H. Guyford Stever

Douglas K. Struck

Linda L. Stryker

Ziro Suzuki

David F. Swensen

Georges M. Temmer

Heinz Tiedemann

Scott B. Tollefsen

U.S. Department of Agriculture

U.S. Department of Energy

U.S. National Aeronautics and Space

Administration
U.S. National Science Foundation
U.S. National Institutes of Health
U.S. Office of Naval Research
University of Massachusetts
University of Texas
William B. Upholt
Thomas and Mary Urban
John L. Weinberg Family Fund
Sidney J. Weinberg, Jr. Foundation
James A. Weinman
A. Morris Williams Jr.
Marthe Wilson
Evelyn M. Witkin
Frederick T. Wolf
Bernard J. Wood
Kenzo Yagi
Masaru Yamaguchi
Violet K. Young
Western Regional Center for the National

Institute for Global Environmental Change
Helen Hay Whitney Foundation
Woods Hole Oceanographic Institution

168

1301 K Street, N.W. 800W Telephone 202 414 1000

Washington, DC 20005-3333

Price Waterhouse llp

#

REPORT OE INDEPENDENT ACCOUNTANTS

December 15, 1994

To the Auditing Committee of the
Carnegie Institution of Washington

In our opinion, the accompanying statement of assets, liabilities and fund balances and the
related statement of revenue, expenses and changes in fund balances present fairly, in all
material respects, the financial position of the Camegie Institution of Washington (the
Institution) at June 30, 1994 and 1993, and the results of its operations and the changes
in its fund balances for the years then ended in conformity with generally accepted
accounting principles. These financial statements are the responsibility of the Institution's
management; our responsibility is to express an opinion on these financial statements based
on our audits. We conducted our audits of these statements in accordance with generally
accepted auditing standards which require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting the
amounts and disclosures in the financial statements, assessing the accounting principles
used and significant estimates made by management, and evaluating the overall financial
statement presentation. We believe that our audits provide a reasonable basis for the
opinion expressed above.

Our audits were made for the purpose of forming an opinion on the basic financial
statements taken as a whole. The supporting Schedules 1 through 4 are presented for
purposes of additional analysis and are not a required part of the basic financial statements.
Such information has been subjected to the auditing procedures applied in the audits of the
basic financial statements, and in our opinion, is fairly stated in all material respects in
relation to the basic financial statements taken as a whole.

Tfo U)<*cJU"^ LJ-P

169

Carnegie Institution of Washington
Financial Statements

Statement of Assets, Liabilities, and Fund Balances
June 30, 1994 and 1993

1994 1993
ASSETS
Current assets

Cash and cash equivalents $ 139,563 $ 85,943

Grants receivable 2,416,831 2,472,666

Accounts receivable and other assets 1,628,662 535,756

Accrued interest and dividends receivable 1,154,145 1,303,490

Bond proceeds held by trustee (cost of $28,608,237) 28,002,077 ...

Total current assets 33,341,278 4,397,855

Investments, at market*

Temporary 15,889,760 26,690,677

Corporate stocks 129,544,822 140,125,108

Fixed income 68,060,889 79,355,829

Limited partnerships 59,954,993 28,039,642

Other 227,846 249,379

Total investments 273,678,310 274,460,635

Property, plant, and equipment

Buildings and building improvements 29,119,098 28,981,172

Scientific equipment 10,329,163 9,780,856

Telescopes 7,910,825 7,910,825

Administrative equipment 1,936,450 1,857,752

Land 1,086,742 1,086,742

Art and historical treasures 34,067 34,067

Less: accumulated depreciation (16,547,169) (14,976,894)

Property, plant, and equipment in service . . 33,869,176 34,674,520

Telescope under construction 7,016,424 3,466,171

Buildings under construction 2,617,161 273,476

Scientific equipment under construction .... 904,421 663,232

Total under construction 10,538,006 4,402,879

Net property, plant, and equipment .... 44,407,182 39,077,399

Total assets $351,426,770 $317,935,889

LIABILITIES AND FUND BALANCES
Current Liabilities

Accounts payable and accrued expenses .... $ 2,748,606 $ 1,685,069

Deferred grant income 3,647,313 3,552,360

Broker payable _^_^ 5,350,934

Total current liabilities 6,395,919 10,588,363

Bonds payable 34,918,382 „.

Fund balances 310,112,469 307,347,526

Total liabilities and fund balances . . . $351,426,770 $317,935,889

*Cost on June 30, 1994: $248,883,120 (temporary $15,889,760, corporate stocks $107,850,484, fixed income
$70,925,277, lim. partnerships $53,989,753, other $227,846). Cost on June 30, 1993: $236,409,624 (temporary
$26,690,677, corporate stocks $110,330,722, fixed income $74,138,846, lim. partnerships $25,000,000, other $249,379).

The accompanying notes are an integral part of these financial statements.

170

Carnegie Institution of Washington
Financial Statements

Statement of Revenue, Expenses, and Changes in Fund Balances
for the Years Ended June 30, 1994 and 1993

Year Ended June 30,

1994 1993
Revenue

Investment earnings

Interest and dividends $ 7,584,076 $ 8,479,164

Realized net gain on investments 20,485,633 23,581,840

Less: investment service fees (837,027) (875,680)

Net investment earnings 27,232,682 31,185,324

Grants

Federal 7,105,200 5,409,796

Private 3,957,005 3,734,707

Gifts and other revenues 763,860 490,351

Total revenue 39,058,747 40,820,178

Capital contributions— equipment 946,083 1,410,449

Total revenue and capital contributions 40,004,830 42,230,627

Expenses

Personnel and related 15,491,282 14,102,785

Equipment 3,623,032 3,889,058

General 6,755,623 6,015,350

Total expenses 25,869,937 24,007,193

Excess of revenue and capital contributions

over expenses before capital changes .... 14,134,893 18,223,434

Capital changes

Unrealized net (loss) /gain on investments .... (13,861,981) 8,197,955

Capital campaign— gifts 2,492,031 2,100,207

Total capital changes (11,369,950) 10,298,162

Excess of revenue, capital contributions,

and capital changes over expenses 2,764,943 28,521,596

Fund balances, beginning of period 307,347,526 278,825,930

Fund balances, end of period $310,112,469 $307,347,526

The accompanying notes are an integral part of these financial statements.

171

Carnegie Institution of Washington
Femancial Statements

Notes to The Financial Statements, June 30, 1994 and 1993

The Carnegie Institution of Washington (the Institution)
is an institution for advanced research and training in the
sciences. It carries out its work in five research centers: the
Departments of Embryology, Plant Biology, and Terrestrial
Magnetism, the Geophysical Laboratory, and the
Observatories (astronomy). The Institution is exempt from
federal income tax under Section 501(c)(3) of the Internal
Revenue Code (the Code). Accordingly, no provision for
income taxes is reflected in the accompanying financial
statements. The Institution is also an educational
institution within the meaning of Section 170(l)(A)(ii) of
the Code. The Internal Revenue Service has classified the
Institution as other than a private foundation, as defined
in Section 509(a) of the Code.

Note 1. Significant Accounting Policies

Basis of Accounting

The financial statements of the Institution are prepared
on the accrual basis of accounting. The endowment and
special funds reflected in the accompanying Schedule 2,
Changes in Fund Balances, include gifts and bequests
accepted by the Institution with the understanding that the
principal and income be utilized in accordance with the
terms of the gifts and bequests.

Investments

The Institution considers all highly liquid debt
instruments purchased with original maturity dates of 90
days or less, excluding amounts that are classified as
temporary investments, to be cash equivalents. Temporary
investments reflect endowment and special fund
investments in short-term instruments that are part of the
investment portfolio. Investments are carried at market
value.

Fair value of financial instruments

Financial instruments of the Institution include grants
and accounts receivable, investments, accounts payable,
and bonds payable. The fair value for investments and
Series A bonds payable is based on quoted market price.
The fair value of grants, accounts receivable, accounts
payable, and Series B bonds payable is approximately
equal to the carrying value.

Property, plant, and equipment

The Institution capitalizes expenditures for land,
buildings, and leasehold improvements, telescopes,
scientific and administrative equipment, and projects in
progress. Routine replacement, maintenance, and repairs
are charged to expense.

Depreciation of the Institution's buildings, telescopes,
and other equipment is computed on a straight-line basis
using the following useful lives: buildings and telescopes,
50 years; building and leasehold improvements, 25 years
or the remaining term of the lease; and scientific and
administrative equipment, 5 years. Depreciation expense
for the years ended June 30, 1994 and 1993 was $2,000,255
and $1,985,417, respectively.

Note 2. Restricted Grants and Gifts

Restricted grants and gifts are funds received from
foundations, individuals, and Federal agencies in support
of scientific research and educational programs. The
Institution follows the policy of reporting revenues only to
the extent that reimbursable expenditures are incurred.
Accordingly, funds received in excess of reimbursable
expenditures are recorded as deferred revenue.
Reimbursement is based upon provisional rates which are
subject to subsequent audit by the Institution's Federal
Cognizant agency.

Note 3. Forward Contracts

The Institution enters into forward exchange contracts
to hedge transactions on a continuing basis for periods
consistent with its committed exposures; the Institution
does not engage in currency speculation. Forward foreign
exchange contracts are for the purchase or sale of foreign
currency or instruments to be delivered on a future date at
a rate fixed on the contract date.

The Institution's foreign exchange contracts do not
subject the Institution to risk due to exchange rate
movements because gains and losses on these contracts
offset losses and gains on the equity and fixed income
securities being hedged. The gains or losses on these
contracts are included in unrealized and realized net gains
on investments in the period in which the exchange rates
change. As of June 30, 1994 and 1993, the Institution had
approximately $8,953,000 and $10,793,000, respectively, of
foreign exchange contracts outstanding, primarily
denominated in French Francs and Deutschemarks. The
forward exchange contracts generally have varying
maturities, none exceeding three months.

The Institution also invests in forward commitment
transactions involving mortgage-backed securities issued
by the Government National Mortagage Association and
the interest rate and specific security underlying the
transaction are determined shortly before settlement. At
June 30, 1994 the Institution had an investment of
approximately $5,656,000 in these forward commitment
transactions.

Note 4. Other Investments

In order to assist in the relocation of certain key
scientific staff, the Institution makes loans secured by real
estate to these employees at below-market interest rates.
At June 30, 1994 and 1993, their outstanding value was
$227,846 and $249,379, respectively.

Note 5. Bonds Payable

On November 1, 1993 the Institution issued $17.5
million each of Series A and Series B California Educational
Facilities Authority Revenue tax-exempt bonds. Bond
proceeds are used to finance the Magellan project and the
renovation of the facilities of the Observatories at
Pasadena.

172

Carnegie Institution of Washington
Financial Statements

Notes to the Financial Statements, June 30, 1994 and 1993 (continued)

Series A bonds bear interest at 5.6% payable in arrears
semiannually on each April 1 and October 1 and upon
maturity on October 1, 2023. Series B bonds bear interest at
variable money market rates in effect from time to time,up
to a maximum of 12%, over the applicable money market
rate period of betwen 1 and 270 days and have a stated
maturity of October 1, 2023. At the end of each money
market rate period, Series B bondholders are required to
offer the bonds for repurchase at the appliable money
market rate. If repurchased, the Series B bonds would be
resold at the current applicable money market rate and for
a new rate period.

The Institution is not required to repay the Series A and
B bonds until the October 1, 2023 maturity date, and the
Institution has the intent and the ability to effect the
purchase and resale of the Series B bonds through a tender
agent; therefore the bonds payable are classified as long
term. Sinking fund redemptions begin in 2019 in
installments for both series. The fair value of bonds
payable at lune 30, 1994 is approximately equal to
$34,847,000. The fair value of Series A is based upon the
quoted market rates, and the fair value of Series B bonds is
assumed to approximate carrying value at lune 30, 1994,
as the mandatory tender dates on which the bonds are
repriced are generally less than three months before and
after year end.

Note 6. Realized and Unrealized Gain and Loss on
Investments

The realized and unrealized gain and loss on
investments for the years ended June 30, 1994 and 1993 for
the fixed income and equity portions of the Institution's
investment portfolio are as follows:

Unrealized
Realized gain gain (loss)

Year ended June 30, 1994

Fixed income $ 2,417,000 $ (6,010,000)

Equity $18,069,000 $ (7,852,000)

Total $20,486,000 $(13,862,000)

Year ended June 30, 1993

Fixed income $ 7,602,000 $ 789,000

Equity $15,980,000 $ 7,409,000

Total $23,582,000 $ 8,198,000

Note 7. Employee Benefit Plans

The Institution has a noncontributory, defined
contribution, money-purchase retirement plan in which all
United States personnel are elibible to participate.
Beginning April 1, 1989, the Plan has been funded through
individually owned annuities issued by Teachers'
Insurance and Annuity Association (TIAA) and College
Retirement Equities Fund (CREF). There are no unfunded
past service costs. The total contributions made by the
Institution were $1,532,862 in 1994 and $1,385,155 in 1993.
After one year's participation, an individual's benefits are
fully vested.

The Institution provides health insurance for retired
employees. Most of the Institution's United States
employees become eligible for these benefits at retirement.
The cost of retiree health insurance benefits is currently
being recognized as an expense as costs are incurred. For
the years ended lune 30, 1994 and 1993, these costs were
$393,044 and $376,128, respectively.

The provisions of Statement of Financial Accounting
Standards No. 106, "Employer's Accounting for Post
Retirement Benefits Other Than Pensions," have not yet
been adopted by the Institution. This Statement requires
that the cost of such benefits be estimated in advance and
recognized over the period earned. The Institution will be
required to adopt the provisions of this Statement for the
fiscal year ending lune 30, 1996. The impact of this
Statement on the Institution's financial statements has not
been determined.

173

2

-

7

W

■ J

:_

J

/-

=

r

^

S

P

Q

<

H

w

£

(J)

£

_^

<"

i ;

^

: >

CD

/-

y

y

<

en

ON

ON

H

^

2

Q

w

2

2

<

H

^

Pd

On

<

On

Ph

rH

W

Q

CO

w

2

01

Z

Q

pq

w

Cu

Q

X

2

W

O

C/3

w

<

rJ

UJ

p

><

Q
w
X
U

m

P4

en

H x

en
-

«J B

H x
ffl

u

B <a

m^oMn>oo

LX

00 CO IX 00

NO

CO

O O LO O LO Tfn O

NO

vO O fN (N

(N

ON

LO 00 NO "* On 00 On

o

CO CM ^ t— i

O ^ (N -* ^ (N ON

IX

^ 00 H VO

o

IX

00 NO •** On nO ^tf 00

IX

NO IX ^ IX

CO

o

rH ** CO LO CN "^ (N

LO

CO rH LO CO

^

o

CO "* ^ ^h" CO rH

CN

Tt?

<&■

CM

^f LO CO LX CO tX IX

NO

CO NO 00 <HH

f_|

LX

CM O "HH O LO O IX

ON O LX 'HH

CM

CO

co cm ix co co on no

LO

On LO 00 O

^v

ON^

CM LO 00 NO CO 00 LO

o

Tf IX CO CO

on"

ON

CO O O LO xf O 00

«*

CO LX CM On

CM

NO

ON LX "HH IX 00 "HH LO

NO

CO rH CO CO

CMv

°°v

CO "* "^ «* CO rH

co"

cm"

LO

<bB-

CM

CM

IX 00 On LX 00 ** CM
00 NO "HH NO CO O On
CN nO On 00 lov CM^ **
CM" CO" h Lx" oo" no h
O CM 00 00 00 rf CM
LO NO 00 00 LO "HH

^ CO O O 00

: lo

o

IX ^ O LO ^

. a)

o

O O CO IX 00

CM

CM LO NO CM ^

<tf

in

CO "* On CM "Hh

NO

o

CM "* CO «* "*

r—<

^

rH rH CM rH

LX

CO 'HH "HH O IX CO

NO On ON ON NO O

ON <* "^ NO ON tX

tx no" O LO On" CM"

On CO CO ^t1 O NO

t-H nOv h «tf 00^ CO

CM CO" CM" rH rH r-H

X

PO

03

EC

B

£

03
U

03

co no oo ^

ON O LX ^*

on lo_ orj co

»* tx" CO" CO"

CO LX CM ON

CO rH CO CO

o

bX5 o

- S C
^°£CQ 03

8 g js 2 ^

UwChCqO

rH

CM

CM

CO

<HH

LX

ON

CM

M

CM

00

CM

^h

m

oj:

03

S-H

to

en

B

S-H

03

Vh

B
en

13

03
>

B

T3
<

°3 Sfi

3 Hi

Oh B

To

■H

M^

M-h

O XJ

Vh

0

0

CO

OJ

L0

0)

u

<D

cu

S-H

.Sifi

SO

T3

<

S 2 u

0£r<

o

C3N
NO

cm" •

v£> X

00 o

> 2

G <D

S3 -b

On Jj
rH jv;

QJ X

Is

03 73

^^

oj £

■—I u

I iS "h

.O CO

174

CN

W

D
O

w

X
U

On
0) °^

ON CM IX t-H r-H

cn in "* ** K

in ov <*" in oo

(NO\CO00 h
CN UTi rH <tf ON
LO H ND~ CO CO
CN
CN

<bft-

O (N O

CN >hh <tf

cn CN in

no in co

ON IX O

oo oo in

vO CN

OOOCOvOOOMHO in tx vO On CO ON r-i CO "* nO_ On tX

in n od h vd n co tC co oo" tC «* xT cn in on o o cn no

oomaHtnNM^TfNom^KinMmHOiN

rtf CO NO rH r-H IX t-h -tf (N (N| \D ^ 00 H

rj? rH in r-H CN

no no

r?,

IX o

NO

r-H O

-T

on oo

fN

NO CO

oo in

CO o

O

CO H

CO

<J)

IT) i< H

ON H 00

CO rH CN

00 ON ON

co ^ oo

■X) in

w m

5 s
g I

On

w

2 co

^ w

s

0)

03

2

o

Fc3

«s

£

Cfl

u

Q

Q

2

W

p

u

PCh

2

2

W

c*

CD

<r

UJ

w

O
2

<

w
X
H

u

C*

CD

c

M-H

(11

TJ

o

£

c

CT3

0

ca

u

T)

CD

f]

U.

w

U)

QJ C O

CU 3 *h

s n3 Qj

co

QJ ON
V ON

3

ix in

O O CO

: o o

: o o

o ix o o :

: o o o o o

cn m

i— i o

O O v£5

• o o

• o o

O ON o o •

• o o o o o

oo m

On CN

O O nO

o o

o o

o oo o o

o o o o o

X) CN

ON IX

o co oo

CN CN

CN CN

ix on in lo

IX O O r}H LD

ON O

<-h in

IX -tf rH

<* w

^CN ^rl

^-"* (N 00 w

nO O

CN O

CN ^^

00 o

CN t-h

v — '

CO CN

CN *— '

*~- ' s — '

<tf

^h CN

r-H

CO

00 NO

CO

IX

^ rH

IX

CN

"tf rt

CO

00

m oo

CO

**

00 CN

NO

oo ix

CO

-t

in oo

CN

CN

CO ^

oo

ON

cn in

1 — 1

"tf

r— I

T-H

omcom^intxcNaNoooocNcoinooNixoomoN
coixmocNooinmooNOcooNiXT— lom^ocNONON

X ^ N N N N H H H CO ON (N CO N O lO N h 00 q

rH CN CN CN tC r-H r-? i-h ^f LO CO*" O^ t-h NO LO LO O tX CO

r-H CO r-H CN r-H rH HH \fl

rH CO

no :

NO •
CO

: co

ON

in

CN

IX

in

<* in

r-H O

IX CN

** xT

oo m

«* ov

NO" r-T

x. : : o : : : oo

00 ■ • O • ■ • IX

cn in oov

in nov on

t-h r-i m

CO
CN

coo^T-HOoooNOOOin^NOixcNcOT-Hixotx
T-ioooco'*T-Hvo>ixT-Hmcomix'*r-i^D^DT-H^oLo

ON o oo in CN 00v t-h t-h CN ^ CN CO O N H \q q CO t-h rH
CO CO CN OO" GO t-H r-H H Tf \0 CO t-H rH NO Ln vO CO ON CO

t-HCOt-HCN t-Ht-H r-ir-iv^)

CN

IX NO

in

NO

NO T-H

-t

r^

IX CO

C 3

-t

CO CN

IX

O 'HH

ri

CO

IX CN

CO

CN

CO

in in m co cn

CN oo NO tx ON
^ on nov no^ cn

0$ O NOV NDV rh
ON NO 00 IX CN
IX in On CO 00

cn in ix

ON NO O
ON Ov <*
NO~ ON rH

on m on

O^COv «**

in cn

a;

5 s

xu

S S c

> c o

c
w

be,

g

in

c« u cn

§1 '

3
o

6 2 s

c o c

O -H O

c « c

Mh CT3

t-h b to

rfl O Oi

CO

cNtxcooNCNcomNDT-HaNCNcocoT-Hixo^cooNNO

T-HOOCOIXONlXO'HHr-Hr-I^OOinCNNOOOOIXT-H

COv CO^ in t-h 00v CN CO^ K rH ON in CO COv •* O^ rH in CN oov in

on in t-h lo cn cn no" no" co no lo co" o on co" in od" o" on in

CNT-Hr-HNOCNIX ^HHfsHHrO^^HHfslrOH^CN

LO CO f-* NO rH t-hnOt-H'HH tN N NO Tf k h

^h" T-H CN T-H CN

c
o

•rj cd

3 oj iS

a; J5 C
3 • - g cn

bD bJO

qj a»

C C

+j sh 5h cn

2
D

cs crj

•j -a §
.§5*3

> cn

O 3

c x a

G cn cn

? 3 fl

O

oo on

NO

T-H [^

rN

in oo

in

<* CN

IX

IX O

-t

NO 'HH

CO

"^ T^

IX

CO

O

CO

&

Dh^h

rP X>

^ JB ^

eg « g u ,_.

0<fQCOUU£tHrHlj2222

QJ CV
Oh C75

ooo

oc a» aj
^h cn cn
OOO

cn

O OJ
bOXi

o o

Ch C>h

C 'p

Qj C

M

& Oh

.5 o

u u o

a> cu g

Cm 0h£

cn cyN >

* 2

CC "Jd

•h ai tj

.s > B

c 2 §

>H (H C 1

S l

T3 "2

r! h

J5 co

175

^AKNhOlh UNMllUllUN Ut- VV AbHUNUlUN

Financial Statements

Schedule 3

lof2

Restricted Grants and Gifts
for the Year Ended June 30, 1994

Balance New Restricted Balance

July 1, 1993 Grants /Gifts Expenses June 30, 1994
Federal grants and contracts

U.S. Department of Agriculture $ 85,100 $ 221,849 $ 80,806 $ 226,143

U.S. Department of Energy 10,332 956,578 352,819 614,091

U.S. Department of the Interior 16,310 ... ... 16,310

U.S. Geological Survey 32,410 ... 32,410

U.S. National Aeronautics and Space

Administration 1,730,050 1,398,662 1,185,846 1,942,866

U.S. National Science Foundation 2,113,035 3,482,638 2,888,397 2,707,276

U.S. Office of Naval Research 98,497 131,000 109,355 120,142

U.S. Public Health Service 1,239,031 2,861,470 2,455,567 1,644,934

Total Federal grants and contracts .... 5,324,765 9,052,197 7,105,200 7,271,762

Private grants

Ahmanson Foundation .... 250,000 ... 250,000

Rita Allen Foundation 22,561 30,000 20,206 32,355

Amer. Assoc, for the Advancement of Science . 3,000 ... ... 3,000

American Astronomical Society 5,586 ... 198 5,388

American Cancer Society 510,300 138,100 131,063 517,337

American Society for Microbiology 3,307 ... ... 3,307

Arnold and Mabel Beckman Foundation .... 34,428 ... 34,428

California Institute of Technology 62,770 20,000 19,462 63,308

Capital Science Lecture Series ... 71,448 ... 71,448

Carnegie Corporation 92,500 12,201 80,299

Carnegie Senior Fellow 43,405 ... 17,598 25,807

Centre National de la Recherche Scientifique . . 10,794 ... 10,794
lane Coffin Childs Memorial Fund for

Medical Research 43,564 55,000 55,583 42,981

Chilean Fellowship 4,500 1,000 ... 5,500

Donnay Fund ... 6,018 ... 6,018

Dudley Observatory 961 17,000 9,758 8,203

Duke University 39 ... ... 39

David Dunlap Observatory 10,789 ... 435 10,354

Embryology Fund 109,981 2,729 210 112,500

First Light/ Academy for Science Education . . 4,466 52,000 55,244 1,222

Flintridge Foundation 138,034 ... 59,777 78,257

Geophysical Fund 16,725 16,725

Robert Hazen 26,259 26,250 ... 52,509

Howard Hughes Medical Institute 44,697 ... 15,646 29,051

Institute for Advanced Study 38,099 ... 38,099

International Human Frontier Science Program 52,104 ... 7,437 44,667

Johns Hopkins University 219,203 ... 84,819 134,384

Johnson & Johnson 12,000 500,000 13,684 498,316

W. M. Keck Foundation 157,846 601,470 26,186 733,130

Kresge Foundation 82,108 ... 67,762 14,346

Lead Trust 1,317,217 960,490 1,255,895 1,021,812

Leukemia Society of America 108,268 ... ... 108,268

Life Sciences Research Foundation 9,499 ... ... 9,499

John D. & Catherine T. MacArthur Foundation . 9,897 ... ... 9,897

Lucille P. Markey Charitable Trust 502,777 ... 164,318 338,459

Martek Biosciences Corporation ... 24,000 15,519 8,481

G. Harold and Leila Y. Mathers

Charitable Foundation 673,943 ... 135,902 538,041

McKnight Endowment for Neuroscience .... 74,474 ... 34,475 39,999

(continued)
176

Carnegie Institution of Washington
Financial Statements

RESTRICTED GRANTS AND GIFTS
(Continued)

Schedule 3

2 of 2

Balance New Restricted Balance

July 1, 1993 Grants /Gifts Expenses June 30, 1994

Andrew W. Mellon Foundation 465,723

John Merck Fund 419,009

Mobil Oil Corporation

Ambrose Monell Foundation 213,710

Monsanto Company

Norton Corporation 35,697

Oxford University 2,172

Observatories Fund 3,040

People's Republic of China 4,285

Plant Biology Fund 850

Proctor & Gamble Co

Richard B. T. Roberts Memorial Fund 1,422

John D. Rockefeller Foundation 3,734

Vera C. Rubin Fund 8,293

Damon Runyon-Walter Winchell

Cancer Foundation 93,527

Alfred P. Sloan Foundation 20,000

Smithsonian Institution 10,000

Space Telescope Science Institute 295,025

State University of New York at Stony Brook . 362,053

Terrestrial Magnetism Fund

Tularik, Inc. Fund 12,013

University of California Santa Cruz 25,802

Uppsala University 2,259

Weizmann Institute 1,042

Western Regional Center of the National Institute

for Global Environmental Change 15,154

Helen Hay Whitney Foundation 235,805

Woods Hole Oceanographic Institution .... _. __

8,921

149,932

324,712

89,446

329,563

20,000

6,554

13,446

150,000

178,390

185,320

20,000

20,000

65,000

67,168

33,529
2,172

7,000

744

9,296
4,285

90

850

90

75,000

15,593

59,407

228

1,650

3,734

1,500

2,580

7,213
93,527

25,000

20,000

25,000

6,881

3,119

632,086

398,025

529,086

800,000

644,083

517,970

(12,013)

25,802
2,259
1,042

7,201

13,850

8,505

80,400

155,405

33,390

12,184

21,206

Total private grants and contracts . . .

Total restricted grants and contracts

Less cash not yet received

from grants and contracts (8,301,797)

Deferred income $3,552,360

6,529,392 4,736,232 3,952,005 7,313,619
11,854,157 $13,788,429 $11,057,205 14,585,381

(10,938,068)
$3,647,313

177

Financial Statements

Schedule 4

Schedule of Expenses

for the Years Ended June 30, 1994 and 1993

1994 1993

Endowment Restricted Total Total

and Special Grants Expenses Expenses

Salaries, fringe benefits, and payroll taxes

Salaries $ 8,215,060 $ 2,722,780 $10,937,840 $ 9,722,006

Fringe benefits and payroll taxes .... 2,246,980 724,733 2,971,713 2,756,489

Retiree health insurance 393,044 393,044 376,128

Total 10,855,084 3,447,513 14,302,597 12,854,623

Fellowship grants and awards 393,588 835,673 1,229,261 1,248,162

Equipment 2,017,954 1,605,078 3,623,032 3,889,058

General expenses

Educational and research supplies 413,313 1,247,497 1,660,810 1,469,860

Contract services 310,965 502,698 813,663 720,771

Building maintenance and repairs 361,821 81,137 442,958 425,097

Utilities 939,064 116 939,180 802,992

Administrative 451,387 115,831 567,218 528,088

Computer services 52,182 20,236 72,418 42,898

Travel and meetings 414,869 458,904 873,773 766,957

General insurance 89,890 96,028 185,918 188,692

Scientific publications 15,567 50,508 66,075 91,066

Professional and consulting fees 216,611 52,458 269,069 395,374

Commissary 42,444 ... 42,444 58,459

Shop 67,568 10,627 78,195 48,333

Telephone 232,980 2,046 235,026 194,071

Postage and shipping 142,578 14,000 156,578 114,883

Books and subscriptions 186,287 7,372 193,659 199,208

Contributions and miscellaneous .... 142,738 77,806 220,544 66,750

Total general expenses 4,080,264 2,737,264 6,817,528 6,113,499

Indirect costs— grants (2,431,677) 2,431,677 ...

Indirect costs capitalized on

scientific construction projects (102,481) (102,481) (98,149)

Total expenses $14,812,732 $11,057,205 $25,869,937 $24,007,193

178

Articles of Incorporation

JtflH-ttgJtjj Congress of tjre lititfl) States of America;

&t the Jfcamd Session,

Begun and held at the City of Washington on Monday, the seventh day of December, one
thousand nine hundred and three.

^lIST act

To incorporate tbe Carnegie Institution of Washington.

Be it enacted by the Senate and House of Representatives of the United
States of America in Congress assembled, That the persons following, being persons
who are now trustees of the Carnegie Institution, namely, Alexander Agassiz,
John S. Billings, John L. Cadwalader, Cleveland H. Dodge, William N. Frew,
Lyman J. Gage, Daniel C. Oilman, John Hay, Henry L. Higginson, William
Wirt Howe, Charles L. Hutchinson, Samuel P. Langley, William Lindsay, Seth
Low, Wayne MacVeagh, Darius 0. Mills, S. Weir Mitchell, William W. Morrow,
Ethan A. Hitchcock, Elihu Root, John C. Spooner, Andrew D. White, Charles
D. Walcott, Carroll D. Wright, their associates and successors, duly chosen, are
hereby incorporated and declared to be a body corporate by the name of the
Carnegie Institution of Washington and by that name shall be known and have
perpetual succession, with the powers, limitations, and restrictions herein contained.

Sec. 2. That the objects of the corporation shall be to encourage, in the
broadest and most liberal manner, investigation, research, and discovery, and
the application of knowledge to the improvement of mankind; and in particular —

(a) To conduct, endow, and assist investigation in any department of
science, literature, or art, and to this end to cooperate with governments,
universities, colleges, technical schools, learned societies, and individuals.

(b) To appoint committees of experts to direct special lines of research.

(c) To publish and distribute documents.

(d) To conduct lectures, hold meetings, and acquire and maintain a library.

(e) To purchase such property, real or personal, and construct such building
or buildings as may be necessary to carry on the work of the corporation.

179

180 CARNEGIE INSTITUTION

(f) In general, to do and perform all things necessary to promote the
objects of the institution, with full power, however, to the trustees hereinafter
appointed and their successors from time to time to modify the conditions and
regulations under which the work shall be carried on, so as to secure the
application of the funds in the manner best adapted to the conditions of the time,
provided that the objects of the corporation shall at all times be among the
foregoing or kindred thereto.

Sec. 3. That the direction and management of the affairs of the corporation
and the control and disposal of its property and funds shall be vested in a board
of trustees, twenty-two in number, to be composed of the following individuals :
Alexander Agassiz, John S. Billings, John L. Cadwalader, Cleveland H. Dodge,
William N. Frew, Lyman J. Gage, Daniel C. Gilman, John Hay, Henry
L. Higginson, William Wirt Howe, Charles L. Hutchinson, Samuel P.
Langley, William Lindsay, Seth Low, Wayne MacVeagh, Darius 0. Mills,
S. Weir Mitchell, William W. Morrow, Ethan A. Hitchcock, Elihu Root,
John C. Spooner, Andrew D. White, Charles D. Walcott, Carroll D. Wright,
who shall constitute the first board of trustees. The board of trustees shall
have power from time to time to increase its membership to not more than
twenty-seven members. Vacancies occasioned by death, resignation, or otherwise
shall be filled by the remaining trustees in such manner as the by-laws shall
prescribe; and the persons so elected shall thereupon become trustees and also
members of the said corporation. The principal place of business of the said
corporation shall be the city of Washington, in the District of Columbia.

Sec. 4. That such board of trustees shall be entitled to take, hold and
administer the securities, funds, and property so transferred by said Andrew
Carnegie to the trustees of the Carnegie Institution and such other funds or
property as may at any time be given, devised, or bequeathed to them, or to such
corporation, for the purposes of the trust ; and with full power from time to time to
adopt a common seal, to appoint such officers, members of the board of trustees or
otherwise, and such employees as may be deemed necessary in carrying on the
business of the corporation, at such salaries or with such remuneration as they may
deem proper; and with full power to adopt by-laws from time to time and such rules
or regulations as may be necessary to secure the safe and convenient transaction
of the business of the corporation; and with full power and discretion to deal
with and expend the income of the corporation in such manner as in their
judgment will best promote the objects herein set forth and in general to have
and use all powers and authority necessary to promote such objects and carry out
the purposes of the donor. The said trustees shall have further power from time

ARTICLES OF INCORPORATION 181

to time to hold as investments the securities hereinabove referred to so transferred
by Andrew Carnegie, and any property which has been or may be transferred
to them or such corporation by Andrew Carnegie or by any other person,
persons, or corporation, and to invest any sums or amounts from time to time
in such securities and in such form and manner as are permitted to trustees
or to charitable or literary corporations for investment, according to the laws
of the States of New York, Pennsylvania, or Massachusetts, or in such securities
as are authorized for investment by the said deed of trust so executed by Andrew
Carnegie, or by any deed of gift or last will and testament to be hereafter made
or executed.

Sec. 5. That the said corporation may take and hold any additional
donations, grants, devises, or bequests which may be made in further support of
the purposes of the said corporation, and may include in the expenses thereof
the personal expenses which the trustees may incur in attending meetings or
otherwise in carrying out the business of the trust, but the services of the
trustees as such shall be gratuitous.

Sec. 6. That as soon as may be possible after the passage of this Act a
meeting of the trustees hereinbefore named shall be called by Daniel C. Gilman,
John S. Billings, Charles D. Walcott, S. Weir Mitchell, John Hay, Elihu Root,
and Carroll D. Wright, or any four of them, at the city of Washington, in
the District of Columbia, by notice served in person or by mail addressed to
each trustee at his place of residence; and the said trustees, or a majority
thereof, being assembled, shall organize and proceed to adopt by-laws, to elect
officers and appoint committees, and generally to organize the said corporation;
and said trustees herein named, on behalf of the corporation hereby incorporated,
shall thereupon receive, take over, and enter into possession, custody, and
management of all property, real or personal, of the corporation heretofore known
as the Carnegie Institution, incorporated, as hereinbefore set forth under "An Act
to establish a Code of Law for the District of Columbia, January fourth, nineteen
hundred and two," and to all its rights, contracts, claims, and property of any
kind or nature ; and the several officers of such corporation, or any other person
having charge of any of the securities, funds, real or personal, books or property
thereof, shall, on demand, deliver the same to the said trustees appointed by this
Act or to the persons appointed by them to receive the same; and the trustees
of the existing corporation and the trustees herein named shall and may take
such other steps as shall be necessary to carry out the purposes of this Act.

Sec. 7. That the rights of the creditors of the said existing corporation
known as the Carnegie Institution shall not in any manner be impaired by the

182

CARNEGIE INSTITUTION

passage of this Act, or the transfer of the property hereinbefore mentioned, nor
shall any liability or obligation for the payment of any sums due or to become
due, or any claim or demand, in any manner or for any cause existing against
the said existing corporation, be released or impaired ; but such corporation hereby
incorporated is declared to succeed to the obligations and liabilities and to be held
liable to pay and discharge all of the debts, liabilities, and contracts of the said
corporation so existing to the same effect as if such new corporation had itself
incurred the obligation or liability to pay such debt or damages, and no such action
or proceeding before any court or tribunal shall be deemed to have abated or been
discontinued by reason of the passage of this Act.

Sec. 8. That Congress may from time to time alter, repeal, or modify this
Act of incorporation, but no contract or individual right made or acquired shall
thereby be divested or impaired.

Sec. 9. That this Act shall take effect immediately.

President of the Senate pro tempore.

By-Laws of the Institution

Adopted December 13, 1904. Amended December 13, 1910, December 13, 1912, December 10, 1937,
December 15, 1939, December 13, 1940, December 18, 1942, December 12, 1947, December 10, 1954,
October 24, 1957, May 8, 1959, May 13, 1960, May 10, 1963, May 15, 1964, March 6, 1967, May
3, 1968, May 14, 1971, August 31, 1972, May 9, 1974, April 30, 1976, May 1, 1981, May 7, 1982,
May 3, 1985, May 9, 1986, May 15, 1987, May 6, 1988, May 5, 1989, May 10, 1991, and May 6,
1994.

ARTICLE I

The Trustees

1.1. The Board of Trustees shall consist of up to twenty-seven members as
determined from time to time by the Board.

1.2. The Board of Trustees shall be divided into three classes approximately equal in
number. The terms of the Trustees shall be such that those of the members of one class
expire at the conclusion of each annual meeting of the Board. At each annual meeting of
the Board vacancies resulting from the expiration of Trustees' terms shall be filled by
their re-election or election of their successors. Trustees so re-elected or elected shall serve
for terms of three years expiring at the conclusion of the annual meeting of the Board in
the third year after their election. A vacancy resulting from the resignation, death, or
incapacity of a Trustee before the expiration of his or her term may be filled by election
of a successor at or between annual meetings. A person elected to succeed a Trustee
before the expiration of his or her term shall serve for the remainder of that term unless
the Board determines that assignment to a class other than the predecessor's is
appropriate. There shall be no limit on the number of terms for which a Trustee may
serve, and a Trustee shall be eligible for immediate re-election upon expiration of his or
her term.

1.3. No Trustee shall receive any compensation for his or her services as such.

1.4. Trustees shall be elected by vote of two-thirds of the Trustees present at a meeting
of the Board of Trustees at which a quorum is present or without a meeting by written
action of all of the Trustees pursuant to Section 4.6.

1 .5. If , at any time during an emergency period, there be no surviving Trustee capable
of acting, the President, the Director of each existing Department, or such of them as
shall then be surviving and capable of acting, shall constitute a Board of Trustees pro tern,
with full powers under the provisions of the Articles of Incorporation and these By-Laws.
Should neither the President nor any such Director be capable of acting, the senior
surviving Staff Member of each existing Department shall be a Trustee pro tern, with full
powers of a Trustee under the Articles of Incorporation and these By-Laws. It shall be
incumbent on the Trustees pro tern to reconstitute the Board with permanent members
within a reasonable time after the emergency has passed, at which time the Trustees pro
tern shall cease to hold office. A list of Staff Member seniority, as designated annually by
the President, shall be kept in the Institution's records.

1.6. A Trustee who resigns after having served at least six years and having reached
age seventy shall be eligible for designation by the Board of Trustees as a Trustee
Emeritus. A Trustee Emeritus shall be entitled to attend meetings of the Board but shall
have no vote and shall not be counted for purposes of ascertaining the presence of a
quorum. A Trustee Emeritus may be invited to serve in an advisory capacity on any
committee of the Board except the Executive Committee.

183

184 CARNEGIE INSTITUTION

ARTICLE II

Officers of the Board

2.1. The officers of the Board shall be a Chairman of the Board, a Vice-Chairman, and
a Secretary, who shall be elected by the Trustees, from the members of the Board, by ballot
to serve for a term of three years. All vacancies shall be filled by the Board for the
unexpired term; provided, however, that the Executive Committee shall have power to
fill a vacancy in the office of Secretary to serve until the next meeting of the Board of
Trustees.

2.2. The Chairman shall preside at all meetings and shall have the usual powers of
a presiding officer.

2.3. The Vice-Chairman, in the absence or disability of the Chairman, shall perform
the duties of the Chairman.

2.4. The Secretary shall issue notices of meetings of the Board, record its transactions,
and conduct that part of the correspondence relating to the Board and to his or her duties.

ARTICLE III

Executive Administration

3.1. There shall be a President who shall be elected by ballot by, and hold office during
the pleasure of, the Board, who shall be the chief executive officer of the Institution. The
President, subject to the control of the Board and the Executive Committee, shall have
general charge of all matters of administration and supervision of all arrangements for
research and other work undertaken by the Institution or with its funds. He or she shall
prepare and submit to the Board of Trustees and to the Executive Committee plans and
suggestions for the work of the Institution, shall conduct its general correspondence and
the correspondence with applicants for grants and with the special advisors of the
Committee, and shall present his or her recommendations in each case to the Executive
Committee for decision. All proposals and requests for grants shall be referred to the
President for consideration and report. He or she shall have power to remove, appoint,
and, within the scope of funds made available by the Trustees, provide for compensation
of subordinate employees and to fix the compensation of such employees with the limits
of a maximum rate of compensation to be established from time to time by the Executive
Committee. The President shall be ex officio a member of the Executive Committee and
the Finance Committee.

3.2. The President shall be the legal custodian of the seal and of all property of the
Institution whose custody is not otherwise provided for. He or she shall sign and execute
on behalf of the corporation all contracts and instruments necessary in authorized
administrative and research matters and affix the corporate seal thereto when necessary,
and may delegate the performance of such acts and other administrative duties in his or
her absence to other officers. He or she may execute all other contracts, deeds, and
instruments on behalf of the corporation and affix the seal thereto when expressly
authorized by the Board of Trustees or Executive Committee. He or she may, within the
limits of his or her own authorization, delegate to other officers authority to act as
custodian of and affix the corporate seal. He or she shall be responsible for the
expenditure and disbursement of all funds of the Institution in accordance with the
directions of the Board and of the Executive Committee, and shall keep accurate accounts
of all receipts and disbursements. He or she shall, with the assistance of the Directors of

BY-LAWS 185

the Departments, prepare for presentation to the Trustees and for publication an annual
report on the activities of the Institution.

3.3. The President shall attend all meetings of the Board of Trustees.

3.4. The corporation shall have such other officers as may be appointed by the
Executive Committee, having such duties and powers as may be specified by the
Executive Committee or by the President under authority from the Executive Committee.

3.5. The President shall retire from office at the end of the fiscal year in which he or
she becomes sixty-five years of age, except as retirement may be deferred by the Board
of Trustees for one or more periods of up to three years each. The corporate officers
appointed by the Executive Committee shall retire, and the Directors of Departments
shall retire as Directors, at the end of the fiscal year in which they become sixty-five years
of age, except as otherwise required by law or as retirement may be deferred by the
Executive Committee.

ARTICLE IV

Meetings and Voting

4.1. The annual meeting of the Board of Trustees shall be held in the City of
Washington, in the District of Columbia, in May of each year on a date fixed by the
Executive Committee, or at such other time or such other place as may be designated by
the Executive Committee, or if not so designated prior to May 1 of such year, by the
Chairman of the Board of Trustees, or if he or she is absent or is unable or refuses to act,
by any Trustee with the written consent of the majority of the Trustees then holding
office.

4.2. Special meetings of the Board of Trustees may be called, and the time and place
of meeting designated, by the Chairman, or by the Executive Committee, or by any
Trustee with the written consent of the majority of the Trustees then holding office. Upon
the written request of seven members of the Board, the Chairman shall call a special
meeting.

4.3. Notices of meetings shall be given ten days prior to the date thereof. Notice may
be given to any Trustee personally, or by mail or by telegram sent to the usual address
of such Trustee. Notices of adjourned meetings need not be given except when the
adjournment is for ten days or more.

4.4. The presence of a majority of the Trustees holding office shall constitute a
quorum for the transaction of business at any meeting. An act of the majority of the
Trustees present at a meeting at which a quorum is present shall be the act of the Board
except as otherwise provided in these By-Laws. If, at a duly called meeting, less than a
quorum is present, a majority of those present may adjourn the meeting from time to
time until a quorum is present. Trustees present at a duly called or held meeting at which
a quorum is present may continue to do business until adjournment notwithstanding
the withdrawal of enough Trustees to leave less than a quorum.

4.5. The transactions of any meeting, however called and noticed, shall be as valid
as though carried out at a meeting duly held after regular call and notice, if a quorum is
present and if, either before or after the meeting, each of the Trustees not present in
person signs a written waiver of notice, or consent to the holding of such meeting, or
approval of the minutes thereof. All such waivers, consents, or approvals shall be filed
with the corporate records or made a part of the minutes of the meeting.

4.6. Any action which, under law or these By-Laws, is authorized to be taken at a
meeting of the Board of Trustees or any of the Standing Committees may be taken
without a meeting if authorized in a document or documents in writing signed by all

186 CARNEGIE INSTITUTION

the Trustees, or all the members of the Committee, as the case may be, then holding office
and filed with the Secretary.

4.7. During any emergency period the term "Trustees holding office" shall, for
purposes of this Article, mean the surviving members of the Board who have not been
rendered incapable of acting for any reason including difficulty of transportation to a
place of meeting or of communication with other surviving members of the Board.

ARTICLE V

Committees

5.1. There shall be the following Standing Committees, viz. an Executive Committee,
a Finance Committee, an Auditing Committee, a Nominating Committee, and an
Employee Benefits Committee.

5.2. All vacancies in the Standing Committees shall be filled by the Board of Trustees
at the next annual meeting of the Board and may be filled at a special meeting of the
Board. A vacancy in the Executive Committee and, upon request of the remaining
members of any other Standing Committee, a vacancy in such other Committee may be
filled by the Executive Committee by temporary appointment to serve until the next
meeting of the Board.

5.3. The terms of all officers and of all members of Committees, as provided for
herein, shall continue until their successors are elected or appointed. The term of any
member of a Committee shall terminate upon termination of his or her service as a
Trustee.

Executive Committee

5.4. The Executive Committee shall consist of the Chairman, Vice-Chairman, and
Secretary of the Board of Trustees, the President of the Institution ex officio, and, in
addition, not less than five or more than eight Trustees to be elected by the Board by
ballot for a term of three years, who shall be eligible for re-election. Any member elected
to fill a vacancy shall serve for the remainder of his or her predecessor's term. The
presence of four members of the Committee shall constitute a quorum for the transaction
of business at any meeting.

5.5. The Executive Committee shall, when the Board is not in session and has not
given specific directions, have general control of the administration of the affairs of the
corporation and general supervision of all arrangements for administration, research,
and other matters undertaken or promoted by the Institution. It shall also submit to the
Board of Trustees a printed or typewritten report of each of its meetings, and at the annual
meeting shall submit to the Board a report for publication.

5.6. The Executive Committee shall have power to authorize the purchase, sale,
exchange or transfer of real estate.

Finance Committee

5.7. The Finance Committee shall consist of not less than five and not more than six
Trustees to be elected by the Board by ballot for a term of three years, who shall be eligible
for re-election, and the President of the Institution ex officio. The presence of three
members of the Committee shall constitute a quorum for the transaction of business at
any meeting.

5.8. The Finance Committee shall have custody of the securities of the Institution and

BY-LAWS 187

general charge of its investments and invested funds and shall care for and dispose of
the same subject to the directions of the Board of Trustees. It shall have power to
authorize the purchase, sale, exchange, or transfer of securities and to delegate this
power. For any retirement or other benefit plan for the staff members and employees of
the Institution, it shall be responsible for supervision of matters relating to investments,
appointment or removal of any investment manager or advisor, reviewing the financial
status and arrangements, and appointment or removal of any plan trustee or insurance
carrier. It shall consider and recommend to the Board from time to time such measures
as in its opinion will promote the financial interests of the Institution and improve the
management of investments under any retirement or other benefit plan. The Committee
shall make a report at the annual meeting of the Board.

Auditing Committee

5.9. The Auditing Committee shall consist of three members to be elected by the
Board of Trustees by ballot for a term of three years.

5.10. Before each annual meeting of the Board of Trustees, the Auditing Committee
shall cause the accounts of the Institution for the preceding fiscal year to be audited by
public accountants. The accountants shall report to the Committee, and the Committee
shall present said report at the ensuing annual meeting of the Board with such
recommendations as the Committee may deem appropriate.

Nominating Committee

5.11. The Nominating Committee shall consist of the Chairman of the Board of
Trustees ex officio and, in addition, three Trustees to be elected by the Board by ballot for
a term of three years, who shall be eligible for re-election, but, after serving for two
consecutive terms, not until after the lapse of one year. Any member elected to fill a
vacancy shall serve for the remainder of his or her predecessor's term. The Chairman of
the Board shall appoint a member of the Committee as Chairman for a term expiring no
later than the expiration of his or her term as a member.

5.12. Sixty days prior to an annual meeting of the Board the Nominating Committee
shall notify the Trustees by mail of the vacancies to be filled in the membership of the
Board. Each Trustee may submit nominations for such vacancies. Nominations so
submitted shall be considered by the Nominating Committee, and ten days prior to the
annual meeting the Nominating Committee shall submit to members of the Board by
mail a list of the persons so nominated, with its recommendations for filling existing
vacancies on the Board and its Standing Committees. No other nominations shall be
received by the Board at the annual meeting except with the unanimous consent of the
Trustees present.

Employee Benefits Committee

5.13. The Employee Benefits Committee shall consist of not less than three and not
more than four members to be elected by the Board of Trustees by ballot for a term of
three years, who shall be eligible for re-election, and the Chairman of the Finance
Committee ex officio. Any member elected to fill a vacancy shall serve for the remainder
of his or her predecessor's term.

5.14. The Employee Benefits Committee shall, subject to the directions of the Board
of Trustees, be responsible for supervision of the activities of the administrator or
administrators of any retirement or other benefit plan for staff members and employees

188 CARNEGIE INSTITUTION

of the Institution, except that any matter relating to investments or to the appointment
or removal of any trustee or insurance carrier under any such plan shall be the
responsibility of the Finance Committee. It shall receive reports from the administrator
or administrators of the employee benefit plans with respect to administration, benefit
structure, operation, and funding. It shall consider and recommend to the Board from
time to time such measures as in its opinion will improve such plans and the
administration thereof. The Committee shall submit a report to the Board at the annual
meeting of the Board.

ARTICLE VI

Financial Administration

6.1. No expenditure shall be authorized or made except in pursuance of a previous
appropriation by the Board of Trustees, or as provided in Section 5.8 of these By-Laws.

6.2. The fiscal year of the Institution shall commence on the first day of July in each
year.

6.3. The Executive Committee shall submit to the annual meeting of the Board a full
statement of the finances and work of the Institution for the preceding fiscal year and a
detailed estimate of the expenditures of the succeeding fiscal year.

6.4. The Board of Trustees, at the annual meeting in each year, shall make general
appropriations for the ensuing fiscal year; but nothing contained herein shall prevent the
Board of Trustees from making special appropriations at any meeting.

6.5. The Executive Committee shall have general charge and control of all
appropriations made by the Board. The Committee shall have full authority to allocate
appropriations made by the Board, to reallocate available funds, as needed, and to
transfer balances.

6.6. The securities of the Institution and evidences of property, and funds invested
and to be invested, shall be deposited in such safe depository or in the custody of such
trust company and under such safeguards as the Finance Committee shall designate,
subject to directions of the Board of Trustees. Income of the Institution available for
expenditure shall be deposited in such banks or depositories as may from time to time
be designated by the Executive Committee.

6.7. Any trust company entrusted with the custody of securities by the Finance
Committee may, by resolution of the Board of Trustees, be made Fiscal Agent of the
Institution, upon an agreed compensation, for the transaction of the business coming
within the authority of the Finance Committee.

6.8. The property of the Institution is irrevocably dedicated to charitable purposes,
and in the event of dissolution its property shall be used for and distributed to those
charitable purposes as are specified by the Congress of the United States in the Articles
of Incorporation, Public Law No. 260, approved April 28, 1904, as the same may be
amended from time to time.

ARTICLE VII

Amendment of By-Laws

7.1. These By-Laws may be amended at any annual or special meeting of the Board
of Trustees by a two-thirds vote of the members present, provided written notice of the
proposed amendment shall have been served personally upon, or mailed to the usual
address of, each member of the Board twenty days prior to the meeting.

Index

Abelson, Philip H., v, vi, 161, 163, 164, 167

Abbott, Jennifer, 47

Adam, Luc, 71

Aguilar, Carmen, 101

Ahnn, Joohong, 47

Aldrich, L. Thomas, 131

Alexander, Conel, 21, 108-109

Andersen, Jens Christian, 101

Angel, Ross, 24

Apt, Kirk, 71

Arabidopsis thaliana
disease resistance genes in, 51, 55-58
membrane lipids in, 61-64
phototrophic mutants of, 67-68

Atzel, Amy, 47

Babcock, Horace, 153, 167
Bai, Jining, 41, 47
Barruol, Guilhem, 131
Bauer, Donna White, 47
Bell, David, 77

Short report, 89-90
Bell, Peter, 101
Berkelman, Thomas, 71
Berry, Joseph, vii, 71

Short report, 65-66
Bertka, Constance, 101
Bjarnson, Ingi, 131
Bjorkman, Olle, 53, 71

Short report, 66-67
Bocherens, Herve, 101
BOREAS, 65-66
Boss, Alan, 131
Bowers, Ray, vii, 157
Boyd, F. R., 101, 105

Special essay, 109-117
Briggs, Winslow R., 23, 51, 71

Short report, 67-68
Brown, Donald D., vii, 46, 163

Director's introduction, 27-28

Short report, 42
Brown, Louis, 20-21, 108, 131

Buell, Robin, 71

Burner, Harold, 108, 131

Caenorhabditis elegans, muscle differentia-
tion in, 43

Calvi, Brian, 47

Campbell, Andrew, 101

Capital Science Lectures, 4, 14-15, 159

Cardon, Zoe, 72

Carlson, Richard W., 105-106, 131
Special essay, 109-117

Carnegie Academy for Science Education
(CASE), 10, 15-20

Casey, Elena, 72

CASA, 67

Chen, Chii-shiarng, 38, 47

Chen, Lihsia, 47

Chlamydomonas reinhardtii, studies in, 64-65

Cifuentes, Ines, 15, 17, 157

Cohen, Ronald, 76, 77, 90, 101
Short reports, 92, 92-93

Coleman, William T, Jr., v, 161, 163, 164,
167

Collatz, James, 71

Collelo, Gregory, 71

Collier, Jackie, 72

Comet Shoemaker-Levy 9, 3-4, 75, 78-79,
107-108

Conrad, Pamela, 101

Daniel, Steven, 71

David, Edward E., Jr., v, vi, 24, 161

Davies, John, 71

Davidson, Paula, 101

De Jonge, Peter, 22, 153

Dement, Elise, 72

Diebold, John, v, 163

Donahue, Megan, 153

Downs, Robert T, 101

Dressier, Alan, 153

Drosophila

heterochromatin in, 44

pattern formation in, 44

189

190

CARNEGIE INSTITUTION

Duffy, Thomas, 11, 75, 76, 101, 131

Special essay, 78-84

Short report, 90
Dymecki, Susan, 47

Short report, 42^3

Ebert, James D., v, vi, 163, 167

Eggert, Jon, 101

Eliceiri, Brian, 47

Ernst, W. Gary, v, 24, 163, 167

Erysiphe sp., studies with, 53, 55, 57

Faber, Sandra M., v, 167
Falcone, Deane, 71
Fedoroff, Nina V, 46

Special essay, 29-36
Fei, Yingwei, 3, 75, 101

Special essay, 84-89
Ferguson, Bruce W., v, 163, 167
Field, Christopher, 17, 71

Short report, 67
Finger, Larry, 101
Fire, Andrew Z., 46

Short report, 43
First Light, 10, 15, 15-20
Fogel, Marilyn L., 101
Ford, W. Kent, Jr., 131
Fork, David, 71
Foster, Prudence, 131
Franklin, Amie, 72
Frantz, John D., 77, 101

Short report, 92
Fredeen, Arthur, 71
Freedman, Wendy, 23, 153
Frydman, Horacio, 24, 47
Fu, Wei, 71
Furlow, David, 47

Gall, Joseph G., 46

Short report, 43
Garvey, Susanne, vii, 15, 157, 163
Georgieva, Elena, 47
Giere, Reto, 101

Short report, 90-91
Gilmore, Adam, 71
Glaser, Robert, 47
Goelet, Robert G., v, 167
Golden, William T, v, 161, 163, 164
Golgher, Denise, 24
Goncharov, Alexandre, 101
Goodfriend, Glenn, 101

Short report, 91-92
Graham, John A., 131
Granger, Claire, 72
Greenewalt, Crawford H., 163, 167
Greene wait, David, v, 163
Grossman, Arthur, 71

Short report, 64-65
Guacci, Vincent, 47

Hafstad, Lawrence, 20

Halpern, Marnie, 21

Hanada, Kentara, 40, 47

Hanfland, Michael, 101

Hare, P. Edgar, 101

Haskins, Caryl P., v, vi, 24, 163, 167

Hauri, Erik, 21, 108, 131

Hazen, Robert, 17, 101, 167

Hearst, William R., Ill, v, 163

Heckert, Richard E., v, 161, 163, 164, 167

Helmer, Elizabeth, 47

Hemley, Russell, 79, 90, 101

Herold, Lori K., 131

Hewlett, William R., v, 167

High-pressure studies, 75-77

of Earth's core, 84-89, 93-94

of Jupiter's interior, 78-84

of magnesium oxide, 90, 92

of stishovite, 92-93
Hill, Bob, 153
Hoang, Nguyen, 131
Hoering, Thomas, 77, 101

Short reports, 89-90, 92
Hoffman, Neil E., 71

Short report, 66
Holbrook, Michele, 72
Hornblower, Marshall, vii, 163
Hu, Jingzhu, 101
Hubble Space Telescope, 3

Ilchik, Robert, 101
Inamori, Kazuo, v, 167
Inbar, Iris, 76, 101

Short report, 92
Irvine, T. Neil, 101
Ishikawa, Tsuyoshi, 131
Isotope studies

of mantle materials, 106, 109-117

James, Charles, 10, 15, 157
Essay on First Light and CASE, 15-20

James, David E., 107, 131

Joel, Geeske, 72

Johnson, Antonia Ax:son, v, vi, 161, 164,
167

Johnson, Beverly, 101

Jupiter
interior structure of, 78-84
coment impacts on, ?>-A, 75, 108

Kanamori, Akira, 47
Kehoe, David M., 71
Kells, William, 153
Kelley, Deborah, 77, 102

Short report, 92
Kelly, William, 47
Keyes, Linda, 47
Kingma, Kathleen, 23, 77, 101

Short report, 92

INDEX

191

Kluge, Mark, 101
Kohler, Robert, 159
Kokis, Julie, 101
Koshland, Douglas, 46

Short report, 43^14
Kristian, Jerome, 153
Krzeminski, Wojciech, 153
Kunkel, William, 153

Langone, Kenneth G., v, 163

Laubach, Gerald D., v, 161, 163, 167

Landy, Stephen, 153

Lavery, Russell J., 131

Li, Ming, 101

Li, Xingxiang, 71

Lilly, Mary, 47

Lin, Haifin, 47

Linde, Alan T., 23, 131

Lindley, Catharina, 72

Lipid studies
in animal cells, 36-42
in plant membranes, 59-64

Liscum, Emmanuel, 71

Liu, Lanbo, 131

Lively, John J., vii, 157, 163

Lund, Chris, 72

Oeller, Paul, 71
Ogas, Joseph, 71
Okkema, Peter, 47
Olney, Margaret, 72

Pagano, Richard E., 23, 46

Special essay, 36^42
Palmer, Julie, 71
Patel, Nipam, 47

Short report, 44
Paul, Pascal, 47
Pearson, Graham

Special essay, 109-117
Pellegrini, Luca, 47
Perkins, Richard S., v, 163, 168
Persson, Eric, 153
Petry, Clinton, 20
Photorropism, regulation by blue light,

67-68
Pilgrim, Marsha, 71
Poindexter, Parti, 72
Poirier, Yves, 71
Press, Frank, 22-23, 101, 131
Preston, George, 135, 139, 140, 153
Prewitt, Charles T., vii, 101, 163

Director's introduction, 75-77

Macomber, John D., 163, 164, 168
Magellan Project, 2, 3, 135
Majewski, Steve, 153
Malmstrom, Carolyn, 72
Mao, Ho-kwang, 80, 90, 101
Margolis, Jonathan, 47
Martin, William McChesney, Jr., v, 168
McCarthy, Patrick, 153
McClintock, Barbara, 29
McGovern, Patrick, 124, 131
McWilliam, Andrew, 135, 153

Special essay, 136-141
Meade, Charles, 101
Meluh, Pamela, 47
Meserve, Richard A., v, 24, 161, 163, 164,

167
Miller, Thomas, 20
Montgomery, Mary, 47
Morris, Julie, 21, 108, 131
Murphy, David, 153
Murphy, Franklin, 20
Myhill, Elizabeth, 131
Mysen, Bjorn O., 101

Namiki, Noriyuki, 131
Na wrath, Christiane, 71
Neufeld, Edward, 47
Neuville, Daniel R., 101
Nikoloff, Michelle, 71
Niyogi, Krishna, 71

Short report, 64-65
Norton, Garrison, v, 168

Quasars, 142-147
Quisel, John, 72

Rabinowitz, David, 108, 131
Racemization studies, 91-92
Raina, Ramesh, 47
Rauch, Michael, 135, 153

Special essay, 142-147
Reiser, Steven, 72
Rhee, Seung, 72
Ride, Sally K., v, 161, 164, 168
Rorth, Pernille, 47

Short report, 44
Roth, Miguel, 153
Rubin, Vera, 17, 23, 131, 167
Rumble, Douglas, III, 101

Short report, 90-91
Russo, Raymond, 101, 131

Sacks, I. Selwyn, 131

Sanchez, Alejandro, 47

Sandage, Allan, 153

Savage, Lina, 47

Schlappi, Michael, 47

Schneider, Lynne, 47

Schwartzman, Rob, 47

Schweizer, Francois, 131

Seamans, Robert C, Jr., v, 24, 161, 163, 164,

168
Searle, Leonard, vii, 140, 153

Director's introduction, 135
Seismic studies, in South America, 107

192

CARNEGIE INSTITUTION

Seydoux, Geraldine, 47

Shectman, Stephen, 136, 139, 153, 163

Shirey, Steven B., 105, 131

Special essay, 109-117
Shu, Jinfu, 101
Silver, Paul G., 107, 131
Simons, Mark, 124, 131
Singer, Maxine, vi, vii, 17, 24, 157, 163, 168

President's commentary, 1-15

publications of, 157
Sivramakrishnan, Anand, 153
Smith, David, 47
Solheim, Larry, 101, 131
Solomon, Sean C, vii, 8, 11, 23, 131, 159, 163

Director's introduction, 105-109
Somayazulu, Madduri, 101
Somerville, Christopher, vii, 21-22, 71, 163

Director's introduction, 51-53

Special essay, 59-64
Somerville, Shauna, 21-22, 53, 71

Special essay, 54-58
Spradling, Allan, vii, 27, 28, 46, 163

Short report, 44
Stanton, Frank, v, 24
Stars, chemical compositions of, 136-141
Stochaj, Wayne, 71
Strunnikov, Alexander, 47
Swensen, David F., v, 161, 163, 164, 168
Synechococcus, studies with, 65

Transposable genetic elements, in maize,

29-36
Turner, Simon, 71
Turner, William I. M, Jr., v, 161, 164

Urban, Thomas N., v, 163, 168

VanDecar, John, 101, 131

Vasquez, Susan, vii, 157, 163

Venus, tectonic evolution of, 106-107,

117-126
Virgo, David, 101
Vos, Willem L., 79, 101

Walter, Michael, 101
Short report, 93-94
Wang, Zhou, 47

Weinberg, Sidney J., Jr., v, 163, 164, 168
Weir, Heather, 24
Weller, Jennifer, 71
Wetherill, George W., 3, 131
Weymann, Ray, 135, 146, 153
Widom, Elisabeth, 131
Willick, Jeffrey, 153
Wolfe, Cecily, 131
Wu, Chung-Hsiun, 47

Xanthomonas campestris, disease resistance
genes in, 55-58

Tera, Fouad, 131
Thayer, Susan, 71
Thompson, Catherine, 47, 56

Short report, 44-45
Thompson, Ian, 21, 153
Thorstenson, Yvonne, 71
Thyroid hormone

role in mammalian nervous system,
44-45

role in amphibian metamorphosis, 42
Timofeev, Jouri, 101
Tourmaline, studies on, 90-91
Townes, Charles, H., v, 24, 163

Yamamoto, Ayumu, 47

Yeast, studies of mitosis in, 43^14

Yeh, Wen-chen, 47

Yildiz, Fitnat H., 71

Yoder, Hatten S., Jr., 23, 101

Young, Edward D., 101

Zabludoff, Ann, 153
Zaritsky, Dennis, 153
Zha, Chang-Sheng, 79, 101
Zhang, James, 71
Zhang, Ping, 47

A GIFT FOR THE FUTURE OF THE
CARNEGIE INSTITUTION OF WASHINGTON

One of the most effective ways of supporting the work of the Carnegie
Institution of Washington is to include the Institution in your estate plans. By
making a bequest, you can support the Institution well into the future.

A bequest is both a tangible demonstration of your dedication to the Carnegie
Institution of Washington and a way to generate significant tax savings for
your estate. Some bequests to the Institution have been directed to
fellowships, chairs, and departmental research projects; some have been
additions to the endowment; other bequests have been unrestricted.

The following sample language can be used in making a bequest to the
Carnegie Institution of Washington:

"I give, and bequeath the sum of $ (or % of my residuary

estate) to the Carnegie Institution of Washington, 1530 P Street, N.W.,
Washington, DC 20005-1910."

For additional information, please call Susanne Garvey, Director of
Institutional and External Affairs, at 202-387-0352, or write:

Susanne Garvey

Director,

Institutional and External Affairs

Carnegie Institution of Washington

1530 P Street, N.W.

Washington, DC 20005-1910