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THE DECENNIAL PUBLICATIONS OF
THE UNIVERSITY OF CHICAGO

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THE DECENNIAL PUBLICATIONS

ISSUED IN COMMEMORATION OF THE COMPLETION OF THE FIRST TEN
YEARS OF THE UNIVERSITY'S EXISTENCE

AUTHORIZED BY THE BOARD OF TRUSTEES ON THE RECOMMENDATION
OF THE PRESIDENT AND SENATE

EDITED BY A COMMITTEE APPOINTED BY THE SENATE

EDWARD CAPPS
STARR WILLARD CUTTING ROLLIN D. SALISBURY

JAMES ROWLAND ANGELL WILLIAM I. THOMAS SHAILER MATHEWS

CARL DARLING BUCK FREDERIC IVES CARPENTER OSKAR BOLZA

JULIUS STIEGLITZ JACQUES LOEB

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THESE VOLUMES ARE DEDICATED

TO THE MEN AND WOMEN

OF OUR TIME AND COUNTRY WHO BY WISE AND GENEROUS GIVING

HAVE ENCOURAGED THE SEARCH AFTER TRUTH

IN ALL DEPARTMENTS OF KNOWLEDGE

INVESTIGATIONS

THE UNIVERSITY OF CHICAGO

FOUNDED BY JOHN D. EOCKEFELLEE

INVESTIGATIONS EEPEESENTING
THE DEPAETMENTS

ZOOLOGY ANATOMY PHYSIOLOGY NEUROLOGY
BOTANY PATHOLOGY BACTERIOLOGY

THE DECENNIAL PUBLICATIONS
FIRST SERIES VOLUME X

CHICAGO

THE UNIVERSITY OF CHICAGO PRESS

1903

Copyright 1903
BY THE UNIVERSITY OF CHICAGO

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CONTENTS

I. On the Production and Suppression of Muscular Twitchings and

Hypersensitiveness op the Skin by Electrolytes - - - 1

By Jacques Loeb, Professor and Head of the Department of Physi-
ology

II. On a Formula for Determining the Weight of the Central Ner-
vous System of the Frog from the Weight and Length of
ITS Entire Body - - - 15-

By Henry H. Donaldson, Professor and Head of the Department of
Neurology

III. The Development of the Colors and Color Patterns of Coleop-

tera, with Observations upon the Development of Color in
Other Orders of Insects (with Plates I-III) . - - 31

By William Lawrence Tower, Assistant in Embryology

IV. The Artificial Production of Spores in Monas by a Reduction

of the Temperature - - - -.- - --71

By Arthur W. Greeley, Assistant in Physiology

V. The Self-Purification of Streams ___--- 79

By Edwin Cakes Jordan, Associate Professor of Bacteriology

VI. The Lecithans: Their Function in the Life of the Cell - 91 — -

By Waldemar Koch, Assistant in Pharmacology

VII. A Contribution to the Physical Analysis of the Phenomena of

Absorption of Liquids by Animal Tissues _ - _ . 103
By Ralph Waldo Webster, Assistant in Physiological Chemistry

VIII. The Distribution of Blood-Vessels in the Labyrinth of the Ear

-7

of Sus Scrofa Domesticus (with Plates V-XII) _ _ - 135
By George E. Shambaugh, Instructor in Anatomy of the Ear, Nose,
and Throat

ix

127055

X Contents

IX. The Animal Ecology op the Cold Spring Sand Spit, with Kemaeks

ON the Theoby of Adaptation ______ 155

By Charles Benedict Davenport, Associate Professor of Zoology and
Embryology

X. The Finer Structure of the Neurones in the Nervous System

OF THE White Rat (with Plates XIII, XIV) - - - - 177
By Shinkishi Hatai, Research Assistant in Nexu-ology

XI. The Phylogeny of Angiospebms - 191

By John Merle Coulter, Professor and Head of the Department of
Botany

XII. Studies in Fat Necrosis - - - - -'- - - 197
By H. Gideon Wells, Instructor in Pathology

XIII. Oogenesis in Saprolegnia (with Plates XV, XVI) - - - 225

By Bradley Moore Davis, Assistant Professor of Botany [Hull
Botanical Laboratory]

XIV. The Early Development of Lepidosteus Osseus (with Plates

XVII, XVIII) -----_-_._ 259
By Albert Chauncey Eycleshymer, Assistant Professor of Anatomy

XV. The Structure of the Glands of Brunner (with Plates XIX-

XXIV) - - - - 277

By Robert Russell Bensley, Assistant Professor of Anatomy

XVI. Mitosis in Pellia (with Plates XXV-XXVII) - - - - 327

By Charles Joseph Chamberlain, Instructor in Morphology and
Cytology

XVII. A Description of the Brains and Spinal Cord of Two Brothers
Dead of Hereditary Ataxia. (Cases XVIII and XX of the
Series in the Family Described by Dr. Sanger Brown); (with
plates XXVIII-XXXIX) - 347

By Lewellys Franklin Barker, Professor and Head of the Depart-
ment of Anatomy. With an Introduction by Dr. Sanger Brown

THE PHYLOGENY OF ANGIOSPERMS

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THE PHYLOGENY OF ANGIOSPERMS

John M. Coulter

The views presented in this paper are in the main based upon numerous
investigations conducted by members of the botanical stafp and graduate students.
The accounts of these investigations, extending through a period of six years, have
been published from time to time, chiefly in the Botanical Gazette, but their bearing
upon the problem of the phylogeny of Angiosperms has never been presented. It would
be confusing to cite the literature involved in this presentation, as it would mean an
extensive bibliography and is in the main familiar to students of the Angiosperms.
The purpose is to present in as compact form as possible the bearings of our present
knowledge upon a problem of great obscurity. The phylogeny of any great group
will probably always remain a baffling problem, incapable of actual demonstration,
and yet theories of phylogeny serve to co-ordinate knowledge and stimulate investigation.
It should be stated that when similarity of structure was taken to be a sure indication
of genetic relationships, the problem promised an approximate solution. But since it
has been proved that similar structures may develop independently, the difficulty of
solution has become apparently insurmountable.

The first phase of the problem has to do with the common or independent origin of
the Monocotyledons and Dicotyledons. The current view assumes their monophyletic
origin, a view based largely upon the great uniformity of the peculiar development of
the female gametophyte. It is argued that the independent origin of such exact details
of development and structures is inconceivable. The peculiar female gametophyte of
Angiosperms, however, has been foimd to vary enough to indicate that it is an extreme
expression of tendencies evident in the heterosporous Pteridophytes and Gymnosperms ;
in other words, an ultimate result of heterospory. Further, nothing is more clear
than that heterospory has originated independently in several plant groups; and the
assumption that its ultimate expressions, the seed and the angiospermous female
gametophyte, have been reached by only one line seems more than improbable.

This somewhat theoretical objection to the current argument in favor of the
monophyletic origin of Angiosperms is strengthened by certain fundamental differences
between the Monocotyledons and Dicotyledons. The differences in the development
of the embryos of the two groups are hard to reconcile upon the theory of monophyletic
origin. Recent investigations of all of those Dicotyledons that have been called
"pseudo-monocbtyledonous," on account of their apparently terminal cotyledon and
lateral stem-tip, have shown a normal dicotyledonous embryology with more or less
complete abortion of one of the cotyledons and displacement of the stem-tip through
the development of the functional cotyledon. Again, the differences in the structure

193

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The Phylogeny of Angiospeems

of the stem and in the character of its vascular bundles are far more difficult to connect
genetically than to refer to a polyphyletic origin, with all that that implies. One of
the strongest arguments against the monophyletic theory comes from historical
testimony. The "Proangiosperms" of the Lower Cretaceous, so far as known, appeared
associated with undoubted Monocotyledons, and merged gradually into recognizable
Dicotyledons, without indicating any relationship to the Monocotyledons. The
emerging of Dicotyledons from this vague group either indicates that they originated
independently, or that the Proangiosperms were transition forms between Mono-
cotyledons and Dicotyledons. The latter alternative is inconceivable, especially since
the most primitive Dicotyledons are now recognized to be more primitive than any of
the Monocotyledons.

It is of interest to note that recent anatomical investigations contradict the current
view that Monocotyledons are the more primitive, and Dicotyledons derived from
them, and show, so far as the development of the vascular system is concerned, that
Monocotyledons are derived from Dicotyledons in case they have a common
phylogeny.

All the testimony available, morphological, historical, and anatomical, seems most
consistent when interpreted in favor of the polyphyletic origin of Angiosperms.

The second phase of the problem is to determine whether the Angiosperms have
been derived from Gymnosperms or from Pteridophytes. The general question is the
same whether one believes in their monophyletic origin or not. The older view is
that Angiosperms are phylogenetically related to Gymnosperms, and Gnetum has been
regarded as the nearest living representative of a transition condition between
Gymnosperms and Angiosperms. The argument is based upon such angiospermous
characters in Gnetum as the absence of archegonia, the organization of eggs while the
gametophyte consists only of free cells, the presence of a perianth and true vessels,
and the dicotyledonous leaves. This showing is certainly strong, and especially in the
structure of the embryo sac does Gnetum show characters that may well illustrate a
stage in the Angiosperm phylum ; but that it actually represents the group from which
the Angiosperms were derived seems unlikely. In fact, the historical argument
against such a claim is very strong, for there is no evidence that Giietum or allied
forms existed among the numerous Angiosperms of the Cretaceous and Tertiary. If
it were related in any way to the origin of so dominant a group as the Angiosperms,
it seems probable that it would have left some evidence of its existence. Nor is it of
special avail to claim that fossil Gnetales may be found in the tropics or in the
Southern Hemisphere, for the great uniformity of climate during early periods has left
the records of tropical vegetation in the temperate and even boreal regions of today ;
so that the strata of the tropics are not likely to reveal prominent types of vegetation
unrepresented in the strata of temperate regions.

The argument from the presence of a " perianth " is particularly vulnerable, since
the structure so-called merely represents the bracts common among Gymnosperms, and

194

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John M. Coulteb

the most primitive Angiosperms have no perianth. Further, the presence of true vessels
in the secondary wood is an argument as much in favor of the origin of Angiosperms
from certain heterosporous Pteridophytes as from Gnetum. Every indication points
to the conclusion that Gnetum is a highly specialized and comparatively recent
member of the Grymnosperm phylum, and as such could not have given rise to the
Angiosperms.

If the Gymnosperms are not the ancestral forms of the Angiosperms, the direct
derivation of the latter from Pteridophytes becomes a matter of course. Perhaps it
was natural to turn at first to the heterosporous Pteridophytes, and among them the
only forms that could seem to be within the range of probability are Selaginella
and Isoetes. The latter has been persistently associated with the origin of the
Monocotyledons, especially in connection with the former idea that Monocotyledons
are the primitive Angiosperm stock. Any supporter of this view now would be almost
forced to maintain the polyphyletic origin of Angiosperms. The most striking
resemblance of Isoetes to the Monocotyledons occurs in the embryo, in which the
single cotyledon is terminal and the stem-tip lateral. A thorough investigation of
Isoetes, however, has developed so many difficulties in the way of accepting it as related
in any way to the Monocotyledons that the theory must be regarded as untenable.

The only possible alternative as to the origin of Monocotyledons, in case they
have arisen independently of the Dicotyledons, is to regard them as the end of a
heterosporous line that developed independently from the eusporangiate Filicales,
whose Pteridophyte members are extinct. Since several independent heterosporous
lines are already recognized, it is not at all necessary to connect any seed-plants with
living heterosporous Pteridophytes.

More important, however, seems to be the determination of the origin of
the Dicotyledons, whether they represent an independent phylum or the primitive
angiospermous stock. The fact that they emerged from the so-called "Proangiosperms,'"
which were largely displayed in the earlier part of the lower Cretaceous, seems to be
fairly well established. The question, therefore, has to do with the origin of the
Proangiosperms. They do not seem to warrant the belief that they represent a common
stock from which both Monocotyledons and Dicotyledons have been derived, for the
Monocotyledons are believed to have existed in unmistakable forms before the large
assemblage of Proangiosperms gave rise to unmistakable Dicotyledons. Still less con-
ceivable is it that Proangiosperms represent the transition forms from Monocotyledons
to Dicotyledons, for nothing in their known structure seems to suggest such a view.
That they were derived from Gnetum-like forms is discredited by the fact that there is
no sure record of the existence of Gnetum at such an early period, and to have given
rise to such an 'assemblage of forms it must have been a conspicuous group.

If we turn to the earlier groups that were sufficiently prominent and at all
suggestive of having given rise to the Proangiosperms, we encounter the Coniferales,
Cycadales, Lycopodiales, and Filicales. The Gymnosperm origin of Dicotyledons

195

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The Phylogeny of Angiosperms

seems to be most unlikely with the exclusion of Gnetum. At the same time, it might
be claimed that Dicotyledons represent an independent line from the Gymnosperm
stock, that advanced in the same direction and much farther than did the Gnetum line ;
but all the essential morphology of the Gymnosperms is less favorable to such an
origin than is that of the heterosporous Pteridophytes.

The Lycopodiales certainly deserve serious consideration in this connection. The
structures of Selaginella are about as suggestive of Dicotyledons as those of Isoetes
are suggestive of Monocotyledons, the embryo being as distinctly dicotyledonous as
that of Isoetes is monocotyledonous, and our study of Selaginella has shown the
strikingly seed-like character of the megasporangium. But a seed may be attained
by any heterosporous line, and Selaginella and even its ancient Lycopodium stock have
too many peculiarities to be considered seriously as ancestral types of Angiosperms.

The only other alternative is that mentioned in connection with the origin of the
Monocotyledons, namely the derivation of the Proangiosperms as an independent
heterosporous line from the abundant ancient eusporangiate Filicales, and this view is
supported by anatomical testimony.

It is becoming increasingly evident that the great marattiaceous plexus of the
Palaeozoic probably gave rise to several heterosporous lines, one or more of which have
certainly been responsible for the Gymnosperms, and others have led to the Angiosperms.
As heterospory may lead to seed-formation in any line, it is inconceivable that only
one or at most two of the numerous heterosporous lines have attained seed-production.
It is more probable that the Angiosperms have arisen from the Marattia-like ferns in
several independent lines ; that the group known as Angiosperms is determined by its
attainment of seed-production rather than its monophyletic origin ; but that in a
certain sense it has a common phylogeny and hence numerous characters in common.

A summary of these conclusions may be stated as follows :

1. The Monocotyledons and Dicotyledons comprise at least two independent
angiospermous lines, and do not represent a single phylum.

2. No Angiosperm phylum has been derived from the Gymnosperms or from
living heterosporous Pteridophytes.

3. All Angiosperm phyla have been derived as independent heterosporous lines
from the ancient eusporangiate Filicales, which also gave rise to* the Gymnosperms.

4. Several Angiosperm phyla probably arose independently from the marattia-
ceous plexus of the PalsBozoic.

5. If Angiosperms have a monophyletic origin, which seems very unlikely, it
seems clear that the Monocotyledons have been derived, from the more primitive
Dicotyledons.

196

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