THE BOTANICAL GAZETTE

.

THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS

THE CAMBRIDGE UNIVERSITY PRESS
LONDON

THE MARUZEN-KABUSHIKI-KAISHA
TOKYO, OSAKA, KYOTO, FUKUOKA, SENDAI

THE MISSION BOOK COMPANY
SHANGHAI

OKT 2
iB uiy
C4

BOTANICAL GAZETTE

VOLUME LXIX
JANUARY-JUNE 1920

WITH TWENTY-THREE PLATES AND ONE HUNDRED NINETY-FOUR FIGURES

Published
January, February, March, April, May, June, 1920

Composed and Printed By
Lig oevomy Aedragen Press
cago, Illinois, U.S.A.

TABLE OF CONTENTS

Second note on certain tee fungus- —— of
living insects (with plates I-V) - - - Roland Thaxter
Upland societies of Petoskey-Walloon Lake region.
Contributions from the Hull Botanical Labora-
tory 256 (with one figure) - - - H. D. Clayberg
Field and laboratory studies of Verbena. Contribu-
tions from the Hull Botanical Laboratory 257
(with plates VI-IX and twenty-six figures) M. Kanda
A chemical analysis of Sudan grass seed. Contribu-
tions from the Hull Botanical rr 58
(with one figure) - F. M. Schertz
Formative effect of high and low temperatures
upon growth of barley: a chemical correlation.
Contributions from the Hull Botanical Labora-
tory 259 (with eighteen figures) - - - H. L. Walster
Physiological study of maple seeds. Contributions
from the Hull Botanical meting! 260 —
two figures) - - - H. A. Jones
Polyembryony among Abietineae. Contributions
from the Hull Botanical — 261 spine
fifteen figures) - - - - John T. Buchholz
Chemical and physical changes during geotropic
response. Contributions from the Hull Botani-
cal Laboratory 262 - - - - Thomas G. Phillips
Ss of scutellum and homology of cloptie in
aize (with eleven figures) - Paul Weatherwax
ae cycle — oe of North America ey
plate X) - - G. R. Bisby
Effect of salts upon oxidase activity of See bark.
Contributions from the Hull Botanical Labora-
tory 263 (with five figures) = (Geo D. H. Rose,
Henry R. Kraybill, and R. C. Rose
Pit-closing membrane in eo bee

plates XI, XII and six figures) - - Gertrude Wright
Dothidiaceous and other Porto Rican Fungi wit

plates XIII, XIV and three figures) - F. L. Stevens

Spermatogenesis in Blasia (with plateXV) - - Lester W. Sharp

v

PAGE

127

179

193

vi CONTENTS VOLUME LXIX

PAGE
Ripening of pears and apples as modified by extreme

temperatures - - - - E.L. Overholser and R. H. Taylor 273
Diaphragms of water plants. II. Effect of certain
factors upon development of air chambers and

diaphragms (with three figures) - - Laetitia M. Snow 297
Life history of Fossombronia cristula. Contributions
from the Hull Botanical Laboratory 264 (with

plates XVI-XIX and one figure) = - - -« Arthur W. Haupt 318
Residual effects of carbon dioxide gas additions to soil

on roots of Lactuca sativa (with five figures) H. A. N. oyes”

and J. H. Weghorst 332

Leaf-base peiiedes among the Liliaceae Been four

gures) - Agnes Arber 337
Development of the ‘Geophigcceae™: - - - - G. H. Duff 341
Temperature and rate of moisture intake in seeds

(with four figures) - - Charles A. Shull 361

Petiolar glands in the ee (with sdules XX, xD
M. J. Dorsey and Freeman Weiss 391
Inheritance of aleurone color in maize. Contribu- gts:
tions from the Hull Botanical Laborstsey me - Merle C. Coulter 407
Bulbils of Lycopodium lucidulum (with twenty-one —
figures) - - - - - - - - R. Wilson Smith 426
Tendrils of Smilax (with plate XXII) - -~— - Agnes Arber 438
enoiy succession of mosses. Contributions from
Hull Botanical saree ii 266 ‘las two
athe - - . . - - Aravilla M. Taylor 449
- Ovuliferous structures of Taxus canadensis. Con-
tributions from the Hull Botanical Laboratory

267 (with plate XXIII and sixty figures) - - A.W. Dupler 492
Rot of date fruit (with five figures) - - - - J.G. Brown 521
BRIEFER ARTICLES—
William Gilson Farlow - eed Me - - Roland Thaxter 83
The Cinchona Station - - - - - D.S. Johnson 347
Chromosome number in the Scouosax - -T.H. Goodspeed
. and M. P. Crane. 348
CURRENT LITERATURE - - 88, 183, 269, 350, 443, 53°

For titles of book reviews see index cs author’s
name and reviews

Papers noticed in “Notes for Students” are ,
indexed under author’s name and subjects

VOLUME LXIX CONTENTS vii

DATES OF PUBLICATION
No. 1 , January 22; No. 2, dhe < 16; No. 3, March 16; No. 4, April 16;
Ne 5, May 15; No. 6, June 17

ERRATA
Vor. LXVIII

P. 431, table I, column 4, for gm. read cm.
P. 435, table II, column 5, for min. read mm.

Vor. LXIX
P. 27, add description of plate V, as follows:
Enterobryus compressus Thaxter

Fic. 47.—Group of 9 individuals producing cysts, with exception of a, young,
and 8, one still bearing normal terminal segment showing attachment to
chitinous integument about anus of host

Fic. 48.—Distal end of cyst-forming individual

Fic. 49.—Base of same individual showing attachment and scattered nuclei

Fic. 50.—Terminal portion of individual from which normal terminal segment
has separated

Fic. 51.—Similar termination in which cyst formation ‘has commenced,
showing nuclei more crowded in region of cyst formation

Fic. 52.—Termination of cyst series

P. 173, line 8 from bottom, for immediately, after adding, read immediately
and after adding

P. 179, line 7 from bottom, for monocotyledonous read dicotyledonous

P. 243, fig. 15, for magnification 1200 read X 600

P. 301, table III, 2.4, 3.0, 3.85, and 3.9 belong to culm 3 in pot DD; 1.9
and 1.6 belong to culm 4 in same pot

P. 303, table V, line 5 under distance, for increased read same

P. 374, line 3 from bottom, for o.098x read 0. 0098x

P. 376, last line, for 0.0286x read 0.0216x

P. 385, line 6 from bottom, after (0.025x-+1) insert +1.65

P. 396, line 6 from top, for figs. 1 and 11 read figs. 6 and 11

VOLUME LXIx NUMBER 1

THE

BOTANICa:: GAZETTE
JANUARY 1920

SECOND NOTE ON CERTAIN PECULIAR FUNGUS-
PARASITES OF LIVING INSECTS:
ROLAND THAXTER
(WITH PLATES I-V)

Although the examination of mycological novelties possesses a
certain fascination, it may have its drawbacks, since in the present,
as in numerous other instances that might be mentioned, their
interest may be neutralized to a considerable extent by their very
novelty, which may be of such a nature as to make it impossible
to assign them a satisfactory position among their fellows, or to
arrive at any reasonable conclusion as to the true significance of
their characteristics. Although from the point of view of the
systematic mycologist, and for his greater peace of mind, Nature
might well have been better employed than in elaborating organ~
isms which, as far as one can see, are in one way or another inter-
lopers in the scheme of organic life, it seems desirable to assemble
them as they appear, since the inevitable accessions to their numbers
may ultimately be expected to supply, in a majority of cases, some
reasonable explanation of their characteristics, which will make it
possible to distribute them satisfactorily in their mycological
pigeonholes.

This situation seems to be well illustrated by many of the
forms included in these parasites of living insects, which if their
isolation were less striking would claim more attention, and have
to be put aside until the discovery of similar and related forms

t Contribution from the Cryptogamic Laboratories of Harvard University, no. 85.

I

2 BOTANICAL GAZETTE - [JANUARY

may serve to make clear their significance. The Laboulbeniales,
being a microcosm in themselves, need no apologist; since, despite
their unsolved origin, their general position in the fungus series is
perfectly clear, except possibly to a few Brefeldians; and, once
they have originated, their extraordinary development is quite in-
telligible. With our present knowledge as a guide, however, the
same can hardly be said of the other external fungus-parasites of
living insects included in this and in my previous paper? on the
same subject. Even in the case of genera like Muzogone and
Muiaria, the similarity of which to well known types is manifest,
it would be very difficult satisfactorily to explain their manifestly
unsuccessful mode of life, the disadvantages of which seem clearly
indicated by their rarity, both as regards individuals and species.
While such forms may be looked upon rather as outcasts from
their proper groups, however, there are others, like Coreomycetopsis,
the Thaxteriolae, and Enterobryae, which must be regarded as
essentially isolated.

This assemblage of species has been obtained from various
parts of the world, on insects belonging to numerous different
genera of the Coleoptera, Diptera, Orthoptera, and Neuroptera,
the most curious forms having been found on Termites, already a
classic ground for the parisitologist. Although the first, Cantharo-
sphaeria, which is a true ascomycete, may perhaps prove to be, in a
sense, saprophytic, with no very definite relation to the vital
activities of its host, this can hardly be said of any of the others,
the life of which is evidently thus conditioned. Termitaria,
Muiogone, Muiaria, and A posporella belong to the Fungi Imperfecti;
the first referable in an artificial way to the Leptostromaceae, but
quite isolated in its characters; the last, one of the Mucedineae,
belonging to a*group which includes a number of forms as yet
unpublished, having a similar mode of life, and characterized by an
absence of differentiated spores, among which the species herewith
illustrated is, in some respects, the most striking. Muiogone and.
Muiaria, of which species have been previously described, belong
tothe Dematiae. The position of all the remaining forms, however,
is problematical, and, although from its cytological characters

2 Bor. Gaz. 58:235—253. pls. 16-19. 1914.

1920] . THAXTER—FUNGUS-PARASITES 3

Enterobryus may’ be assumed to belong to the Phycomycetes,
evident affinities with other members of this class are lacking.
Cantharosphaeria, nov. gen.—Perithecia superficial, scattered,
subdimidiate, membranaceous, ostiolate, the ostiole surrounded by a
tuft of hairs. Asci 8-spored, aparaphysate; spores hyalodidymous.
Cantharosphaeria chilensis, nov. sp. (figs. 1-5).—Perithecia
associated with a rather scanty mycelium of thick-walled, brown,
branching hyphae; subhemispherical, blackish brown, slightly
roughened, seated on the chitinous integument among the bristles
of the host, about 70-804 by 40-45 uy; the apical hairs usually
closely aggregated about the ostiole, 35 X2.5-3 4, about a dozen in
number, rather coarse, irregular, simple, and brown. Asci rather
short and stout, sporiferous to-the small, short, rather abruptly
narrower base, distally rounded, 28X10; ascospores hyaline, the
septum median with a very slight constriction, or the basal segment
slightly shorter and narrower, subdistichous, 12-14 4.5-5 mu.

On the elytra, legs, etc., of a cucujid beetle found in decaying vegetable
material, Corral, Chile.

A single specimen of the becultiee host which bears this fungus was collected
in decaying vegetable material at Corral. It is evidently a beetle of somewhat
unclean habits, since it bears numerous stalked mites, and is covered with a
thin film of foreign matter such as one often sees on species of Silphidae. The
perithecia are numerous, and appear under a hand lens as black points scattered
irregularly over the surface (fig. 1), the individual perithecia nestling among
the peculiar hooked spines of the host as shown in fig. 3, and associated with a
variably developed, brown, thin mycelium of thick-walled branching hyphae
(fig. 2), which can hardly be called a byssus. The terminal hairs eventually
break off, exposing the evident ostiole in old specimens. The surface is
slightly sonhiand and occasionally a hair may be seen projecting apart
from the group about the ostiole.

I have concluded with reluctance to apply a new generic name to this type,
yet its close relationship to other genera does not seem at allclear. It probably
is not truly entomogenous, deriving its nutriment directly from the living
insect, as in all the other types herewith described; and it is not unlikely that
it may obtain its necessary materials from the film of foreign matter which
covers the surface of its host.

Termitaria, nov. gen.—General habit disciform, applanate
or hysterioid, orbicular or variously elongated according to position
of growth, sessile; consisting of a basal pseudocellular layer,

4 BOTANICAL GAZETTE [JANUARY

from which firmly coherent, simple, parallel sporogenous elements
arise vertically, forming an even hymenial surface, the contents of
the upper portion of each element becoming separated to form a
single row of endogenous, simple, hyaline spores, which are dis-
charged through a terminal perforation; the peripheral elements
sterile, dark, indurated, forming a well defined rim or exciple;
the margin in contact with the substratum slightly spreading and
lichenoid.

This structure, which characterizes the mature condition of
this very remarkable type, two species of which have been examined
from living Termites, appears to be a secondary development,
which results from the vertical proliferation of a primary stage
similar to that represented in figs. 6 and 13. This primary con-
dition may be more or less elongated or orbicular, varying to some
extent according to the position of growth; it is formed by a
continuous layer of slightly brownish cells, the whole reducible to
a copiously branched and septate filament, the branches of which
are in lateral contact, the ultimate branchlets forming a radiate
lichenoid margin. As the cells mature and enlarge, there may be
more or less displacement, as a result of which the fundamental
arrangement of the cells in branching filaments may be obscured or
obliterated. The general appearance of this stage, as represented
in the figures cited, recalls that of some species of Asterina or of a
young Aglaozonia or some species of Coleochaete, the resemblance
to the latter being rendered more realistic by the presence of the
projecting bristles of the host, which are completely surrounded
by the advancing margin and are left projecting from the thallus
without displacement. Of the cells which form this primary incrust-
ing layer, many usually become characteristically modified (fig. 13),
assuming the appearance of chlamydospores, which are clearly dif-
ferentiated from the unmodified cells about them by their greater
size, thicker walls, more rounded outline, and deep brown color.
Whether these bodies are ever separated and become functional
spores it has not been possible to determine, although various in-
stances have been seen in which they appear to have been dislodged.

The preliminary stage just described has been seen in only a few
cases, and a complete series, showing the transition from this to the

1920] THAXTER—FUNGUS-PARASITES 5

mature condition, has not been obtained. From such young
specimens as have been examined, however, it is evident that a
proliferation takes place over the surface of the primary stage,
which results in the development of the structures distinguishing
the genus. The primary thallus thus forms a thin substratum,
more or less firmly coherent to the surface of the host, on which
the secondary stage is seated, and which is clearly distinguishable
both in crushed specimens and in sections; the brown chlamydo-
spore-like cells persisting im situ, singly or in groups.

A section of the mature fungus, which under a hand lens has
the appearance of a black Hystertwm when growing on the legs
(fig. 7), or of a small discomycete with pale hymenium and black
margin on other portions of the host (figs. 8, 9), shows a differ-
entiation into several distinct regions. The first is a thin dark
layer of cells, in which many or few of the chlamydospore-like
bodies may be visible at intervals, and which, in a favorable section,
may include the primary attachment of the fungus, an indentation,
associated with a group of dark cells (fig. 14) opposite which the
hypertrophied cells of the host are usually somewhat brownish.
No indication has been seen of any actual penetration of the
parasite through the integument of the host; but these primary —
attachments are readily distinguished, and usually appear as a
limited dark area which shows through the sporogenous region
when the fungus is viewed vertically, as in fig. 9.

Above this primary layer, and derived from it by vertical
proliferation, is a region of irregularly polygonal, hyaline cells,
the origin of which, as components of a series of branching hyphae,
is obscured or quite obliterated through unequal growth and mutual
pressure, and is only indicated by a tendency of the lower cells
to retain an arrangement in vertical rows. The thickness of this
region is somewhat variable, ‘the cells becoming smaller and numer-
ous above; the uppermost giving rise to the straight, erect, tubular,
and apparently always simple filaments which compose the sporo-
genous layer or region. In this layer, which is four or five times as
thick as that from which it is derived, two regions are again
recognizable, the limits of which may be very clearly indicated.
In the lower of these regions the continuous protoplasmic content

6 BOTANICAL GAZETTE [JANUARY

of the individual filaments is more dense, and stains more deeply;
although this distinction becomes less marked in older individuals,
in which, however, the limits of the zone may be even more clearly
marked (fig. 14) through the often deep distal suffusion of the walls.
Above this line of demarcation in the upper zone, which simulates
an ascigerous hymenium, the walls of the upright tubes become
somewhat thicker, gelatinous, and tenaciously coherent; while
the protoplasm of each is segmented to form a series of short
cylindrical spores, which is constantly renewed and pushed upward
by the activities of the denser contents of the lower zone. The
spores separate from one another as they pass into a somewhat
paler region below the surface (fig. 12), becoming slightly rounded
at the extremities, with a few sometimes conspicuous granules.
The discharge of these endogenous spores through the terminal
perforation of the tube has not actually been observed, but is
doubtless effected with some violence, the thickened walls around
the opening, and the mutual pressure of the gelatinous hymenial
elements, combined with the constant pressure from below, afford-
ing an effective mechanism for this purpose. The dimensions of
the sporogenous elements are very small, and owing to their gelati-
nous nature it is usually only with the greatest difficulty that the
limits of single tubes can be distinguished with exactness in sections, —
or in crushed specimens; in fact no outlines are clearly defined in
this region, and even after staining, the minute spores are often
recognized with difficulty under high magnifications. The spores
do not seem to possess a wall, or if they have one it is so thin
as to be hardly demonstrable. Isolated spores are seldom
recognizable on the hymenial surface of healthy individuals, but
when the host is confined for a considerable period under some-
what unfavorable conditions, the normal discharge seems to be
interfered with, and it may become whitish with a coating of
extruded spores.

At the periphery of the hymenium the sporogenous fibes
become sterile, thickened, and blackened, forming the inner portion
of the well defined, deep black-brown rim or exciple; while a narrow,
radiate, lichenoid margin spreads out externally from the base
(figs. 7, 8), in close contact with the surface of the host.

1920] THAXTER—FUNGUS-PARASITES 7

As far as can be determined from the series of specimens ex-
amined, there seems to be no continuous increase of the fungus in
diameter after the original proliferation of the primary stage, which
gives rise to the sporogenous region. This is indicated by the fact
that this region, as soon as spore formation has begun, is surrounded
completely by sterile indurated structures, incapable of radial
extension, and also by the fact that the bristles of the host, which
are surrounded by the filaments of the preliminary stage, are not
bent down as by an advancing margin, but retain their normal
position, and may even be seen projecting beyond the hymenial
surface of mature individuals, as in fig. ro.

Although each individual must produce an enormous number of
spores, this very curious type does not appear to have been very
successful in propagating itself effectively; for although its hosts
are densely gregarious and live under conditions which should be
very favorable for the communication and development of such
parasites, hardly more than 1 per cent of the individuals. in an
_ infected nest appear to bear the fungus. SNyDER, who was the
first to observe the type species of this parasite and to whom I am
greatly indebted for the original material examined, informs me
that he has found this ratio of infection more or less constant in
material from a number of different sources, and SMULGAN,
who has also kindly communicated material from the Boston
region, makes a similar estimate. In the case of the second species,
described from the Island of Grenada, I have also found almost
exactly the same percentage of diseased individuals among the
several thousand hosts examined. 2

It does not appear seriously to inconvenience the insect on
which it grows, and the only indication of injury is a slight brown-
ing of the tissue immediately opposite the primary attachment,
as shown in fig. 14, although all the cells of the tissue lying immedi-
ately below the integument are hypertrophied, wherever the fungus
is in contact with the host, often assuming a rather regular palisade-
like structure, similar to that shown in fig. 10. It is most con-
spicuous when growing on the abdomen (fig. 9), where it is likely
to assume a more regular and rounded form, being suborbicular, or
more often transversely elongated, with an even or sometimes

8 BOTANICAL GAZETTE [JANUARY

slightly irregular outline (fig. 8); but it may also attack the thorax
and head, and very often occurs on the legs, where it assumes a
long fusiform outline, like that of a hysterium (fig. 7). Individuals
of the latter type which have developed on the tibia, from a point
of infection near the terminal claws, are sometimes connected with
the original point of infection by a narrow primary thallus which
remains unchanged on the intervening joints of the leg, spreading
out and producing the secondary stage only on the broader and
more nutritious tibia.

The relationships of this fungus are quite obscure. The
general characters of its primary stage might suggest a resemblance
to some Asterinae, or to a similar incrusting type. Its mature
condition, however, evidently a Fungus Imperfectus, seems to give
it a formal place among the Leptostromaceae. Its method of
sporulation, which in certain respects recalls that of the Chalareae,
or of Sporochisma or Endoconidium among the Hyphomycetes,
would seem to make its position in this group an isolated one.

Termitaria Snyderi, nov. sp. (figs. 13-17).—Characters of the
genus. Sporogenous filaments with blunt or flat perforate termina-
tions forming an even hymenium. ‘Total thickness of sporo-
dochium 70-80; basal region including primary thallus 18-20;
sporogenous region 55-65, the upper zone 25-28 4; sporogenous
hyphae a little over 3 in diameter; free spores about 3.5X2u.
Sporodochium on abdomen 400X 400-1000 yp.

On workers and soldiers of Reticulitermes flavipes and R. virginicus, Wash-
ington, D.C., the former also vicinity of Boston. On Reticulitermes, nov. sp.,
California. On R. lucifugus, Sardinia. A specimen on Rhinotermes marginalis
from Turkeit, British Guiana, kindly communicated by NATHAN Banks, does
not appear to differ from the type. The material, however, is too scanty for
a satisfactory determination.

This form, which is evidently widely distributed, was first observed by
SnypDER, to whom I take pleasure in dedicating it, and who has figured its
gross appearance in fig. 9c, p. 29, Bull. 94, Part Il, Bureau of Entomology.
It was first sent me at his request by A. D. Horxins with an inquiry as to
its possible fungus nature, and has also been brought to my laboratory by both
SNYDER and SMULGAN from the Boston region.

Termitaria coronata, nov. sp. (figs. 6-12) —Sporogenous hyphae
bearing distally a crown of several, more often four, brown-tipped,
*

1920] THAXTER—FUNGUS-PARASITES 9

minute, pointed prolongations which form a minutely echinulate
hymenial surface. Total thickness 80-100 y; basal region including
primary thallus 16-204; sporogenous region 70-78 y, its upper
zone 45-50; sporogenous hyphae X2.5m; spores about 3.5 X2u.

On Eutermes morio var. St. Luciae, Grand Etang, Grenada, B.W.I.

The two species described, although hardly distinguishable in general
appearance, seem to be clearly separated by the minute, dark, toothlike
projections which terminate the sporogenous hyphae in 7. coronata, and give
to the surface of its hymenium a finely punctate appearance which is suggested
with sufficient exactness by the stipple in figs. 7, 8, and, under a high power,
has the appearance represented in fig. 11. In T. Snyderi, on the other hand,
the corresponding terminations are unarmed, blunt, and when viewed from
above show clearly their rounded ends, slightly polygonal from mutual pressure,
and having a readily distinguishable central pore (fig. 15).

The dimensions of the two species, although they are either case,

e usually somewhat different; the sporogenous hyphae of 7. coronata being
slightly larger in diameter and length, the relative length of the portion included
in the upper zone always being greater. The extremities of these hyphae in
this species are quite hyaline and gelatinous, and so tenaciously coherent that
I have been unable either to distinguish clearly the terminal pore, or to trace
definitely to their bases the characteristic terminal toothlike prolongations
shown from above in fig. 11, and laterally in fig. 12. While within the tubes
the spores are evidently compressed, and when free increase in diameter,
becoming more rounded at the extremities.

ome, a, see

Muiogone Medusae, nov. sp. (figs. 18-25).—-Sporophores about
as long as the spores, rather closely septate, densely crowded so
that the whole forms a cushion-like mass on the surface of the
host. Spores somewhat irregular, subpyriform, distinctly broader
distally, uniform pale dirty brownish, consisting of 10-12, more
often 11, more or less regular tiers, the numerous cells of which may
be slightly misplaced, those of the basal and distal tiers often
slightly larger than the rest, but otherwise indistinguishable from
them; a variable number of the distal ones proliferating while
still quite young to form a terminal group of tapering, spirally
coiled, simple or sometimes once branched appendages which may
bear minute secondary spores at their pointed extremities or on
short, pointed, subterminal branchlets. Spores 38-45 X 20-24 4;
terminal appendages 28-30 X4 u at base; stalks, maximum, 38 X6 u.

Io BOTANICAL GAZETTE [JANUARY

On the under surface of the abdomen of Chromopterus sp., Kamerun,
West Africa.

The fly on which this curious form grows is closely related to, if not identical
with, C. delicatulum, which bears the type species of Muiogone. It is quite
unexpected that a genus, which has not been seen on any of the numberless
genera and species of flies from the tropics that I have examined, should be
represented on the same, or on two at least very closely related hosts, by two ©
such clearly distinguished species, of which but one specimen in each instance
is known. The present form, although it has exactly the same gross habit,
and occurs in the same position on the underside of the abdomen, is clearly
distinguished by its uniform pale brown color, the sometimes total absence of
any suggestion of a distinction between basal distal and median regions in the
somewhat more irregular cell-tiers, and especially in the terminal, spiral,
septate, tapering appendages which replace the short spines of the type species,
and the resemblance of which to a Gorgon’s head has suggested the specific
‘name. These appendages are not formed after the spore has matured, but
begin to appear some time before it has attained its full size (fig. 22), although
most of the cell divisions have been completed. There is some variation in
the spirals, which may be quite regular, or rather indeterminate; and although
they usually end in a pointed apex, they may be somewhat blunt. The minute
secondary spores are only recognizable here and there in spores which are still
in situ (figs. 23, 24). The primary spores become detached, together with an
adherent portion of the stalk, and there seems to be no definite mechanism
for abjunction. After having been broken thus, the base of the stalk, which
remains in — proliferates as shown in figs. 18 and 19, so that the spore

ass is tantly renewed. Owing to the presence of the terminal appendages,
as well as the lock of any clear differentiation between the basal, terminal, and
middle regions, the original generic diagnosis should be slightly modified.

Muiaria curvata, nov. sp. (figs. 26, 27).—-Sporophores and sterile
elements springing in small numbers from a compact blackened
base. The spores 2 or 3 in a group; the stalks short, of 5 or 6
cells; the termination rather slender, strongly curved, or character-
istically recurved distally; the body of the spore rather clearly
distinguished, marked by large, very irregular, more or less lon-
gitudinal patches, separated by fine light lines and slightly rough-
ened, the 4 tiers of functional cells rather well defined, including the
broadest portion and with convex margins, the cells relatively
large; the lower of the 3 cells above, and usually the upper of the
2 or sometimes 3 cells below, showing one longitudinal septum;
rather pale yellowish olive brown, the concave side of the termina-

1920] THAXTER—FUNGUS-PARASITES II

tion darker. Body of spore about 52-6020, the termination
65-70 X8, the stalk 50-65 y.

On the superior tip of abdomen and wing of a small drosophilid fly, Bocas
del Toro, Panama (Rorer), no. 2525.

This species is perhaps more nearly allied to M. repens and the succeeding
species. From the former it is distinguished by its 4 clearly defined functional
tiers, its much longer, slender, curved termination, and the absence of an ap-
pendage from the stalk; while from the latter it differs in its smaller size and
quite differently shaped spores. One other American species, also allied to*
M. repens, is known from Trinidad, but more material is desirable before it
can be described.

Muiaria fasciculata, nov. sp. (figs. 28, 29).—Tufts compact, the
spores and rather numerous sterile elements arising from a usually
well defined black base; the stalks relatively long, the termination
relatively slender, and usually curved, but somewhat variable, the
body of the spore blackish brown, roughened by very irre gula
intricate darker markings, the 4 functional tiers well defined,
relatively short, paler, and rather abruptly narrower than the
cells immediately below, of which two are usually flattened, and
one or both longitudinally septate; the cells above 3 or 4, the
lower usually septate. Body of spore 85-100 X 24-28 y, the stalk
1oo-210 yw, the distal termination 50-64 X8 u.

On a dull brown drosophilid fly, no. 2749, Kamerun, West Africa.

This species occurs on the wings, especially on the veins, of its host, a
rather large smoky drosophilid, several specimens of which have been found
to bear it. It is clearly separated from the preceding species by its greater
size and different shape. From M. Lonchaeana, which is the only other form
with which it might be confused, it is distinguished by the fact that the stalk
and distal portion of the spore are not roughened, as well as by its different form.

Aposporella, nov. gen—Mucedinaceous, aposporous, entomo-
genous, a well defined septate axis attached by a blackened foot
and bearing short branches at the septa, which separate short
undifferentiated segments distally that are constantly renew

Aposporella elegans, nov. sp. (figs. 30, 31).—Axis stout, erect,
Straight, or but slightly curved, tapering, simple, the superposed
cells but slightly longer than broad, hyaline, the black foot clearly
defined; the branches short, simple, one to several in an irregular
whorl from all but the terminal cells; somewhat appressed, or but

12 BOTANICAL GAZETTE [JANUARY

slightly divergent, externally edged with blackish brown, except at
the tips; the termination of the axis hyaline, slender, projecting,
without branches. Total length 200-540 <8 yw near the base, where
the cells are 10-14 long. Branches before breaking, longer,
5OX4-5 mM.

On the wings of a small fly, Kamerun, West Africa, no. 2645.

Sufficient material of this graceful form has been examined to convince me
that the individuals figured are fully matured, and that there is no abjunction
" of definitely differentiated spores, a character in which it agrees with a small
assemblage of aposporous Hyphomycetes of which I have half a dozen or more
species from Africa and the East and West Indies that are reserved for future
consideration, and to which reference was made in my former paper (loc.
cit., p. 237).

In this connection it may be mentioned that SpeGAzzint has recently
(loc. cit.) described certain Argentine forms which he refers to Chantransiopsis,
several dubious examples of which, from Africa and the West Indies, I have
myself encountered since the genus was established. One of the forms de-
scribed by SPEGAZzINI under this name, but which seems to me not closely
related to it, is a problematical type which I have examined on Forficulae and
Staphylinidae from the East and West Indies, and from Argentina. It con-
sists of a deep brown, several-septate body, resembling a spore of Hendersonia
for example, elliptical in outline, convex above, and flat below, where it is in
contact with the substratum. From usually the end cells of this body are
developed a group of simple, straight, septate, hyaline hyphae. I have never
seen these hyphae producing anything in the nature of a spore, although
SPEGAZZINI figures one which appears to be developing as a terminal prolifera-
tion. The position and history of this singular form must, I think, remain
somewhat doubtful. Although I have examined hosts well covered with the
brown, septate, primary structures described, I have never seen any that sug-
gested their origin and development, which has led me to suspect that they
might after all prove to be spores of some fungus, not entomogenous, which
develop in situations frequented by the hosts, and adhere to them as the spores
of agarics and other Basidiomycetes adhere to Endomychidae and Erotylidae.
The peculiar form of these bodies, however, and their almost universal germi-
nation in the manner described, make such a supposition doubtful.

In the same paper SPEGAZZINI has described a true species of Chantransi-
opsis which he refers to a new subgenus Asteronycha, based on a slight differ-
ence in the form of its dark attachment. In his comments on these plants he
appears to have misunderstood my expressed opinion in regard to their position,
or at least overlooked my statement, on page 230 of my former paper, that the
genus ‘“‘comprises species belonging to the Hyphomycetes,” and on page 247,
where I mention, in connection with the suggestion that they may be related

1920] THAXTER—FUNGUS-PARASITES 13

to the Florideae or the pie cin that “there seems not the most remote
possibility that such is actually the case

Coreomycetopsis, nov. gen.—Axis consisting of an indeter-
minate series of superposed cells, the basal one modified to form a
characteristic foot attached to the host; the distal portion trans-
formed into a sporogonium, its successive septa being destroyed, or
absorbed, through the upgrowth of sporophores which spring
endogenously from numerous divisions of an intercalary cell,
and abjoint terminally simple hyaline spores; which, after being
set free in the sporogonium, are discharged through a terminal
perforation.

Coreomycetopsis oedipus, nov. sp. (figs. 32, 36).—Nearly hyaline
or faintly yellowish, the foot large, strongly concave externally,
pointed below, its insertion flattened, wholly concolorous with
the remaining cells. Axis usually bent strongly outward above
the foot, consisting of 10-15 cells, including the latter; the sixth or
seventh from the apex becoming proliferous, after dividing to form
a central subpyriform cell and numerous small lateral ones, which
are obliquely separated, and grow up through the lumina of the 5
or 6 cells above, abjointing terminally long oval spores somewhat
pointed at the base; the cells above, and including the proliferous
cell, transformed into a straight symmetrical sporogonium, clearly
differentiated, and fusiform or obclavate in outline, broader than
the 4-6 subequal stalk-cells which connect it with the foot. Total
length 100-135. Sporogonium 45—60X12-15 y; stalk rou; foot
25 X12-15 mu; spores 8-9 X2-2.5 wu.

_ On the tips of the legs of Eutermes morio var. St. Luciae, Grand Etang,
Grenada.

This form is usually solitary, attached to the terminal joints of the legs,
and from its pale color is not readily seen, although it is larger than many
Laboulbeniales. Its remarkable analogy to Coreomyces is suggested by the
generic name selected, and if the spores were formed in asci, instead of being
abjointed, it would be placed near that genus, since the history of develop-
ment of its sporogonium, and that of the perithecium in Coreomyces, is re-
markably similar. The destruction of the upper cells to form the common
teh of the sporogonium does not appear to be due wholly, at least, to the

upward pressure of the traversing sporogéenous elements, since these cells
evidently begin to disorganize as soon as the first intercalary divisions appear

14 BOTANICAL GAZETTE [JANUARY

(figs. 33, 35), and the uppermost septa are not reached by the sporiferous
filaments themselves.

In general appearance this plant is so like some of the Laboulbeniales
that at first I was inclined to believe that it might prove to be the male in-
dividual of some ascigerous form characterized by an entirely new type of
antheridial structure. ._ Its development, however, is so widely different from
anything hitherto known among the Laboulbeniales that there seems to be no
good reason to suppose, in the present condition of our knowledge of such
parasites, that it is even remotely related to them, an opinion which is sup-
ported by the fact that a careful search has failed to bring.to light individuals
of a different nature. Since, however, its relation to other types of fungi is
equally problematical, it will have to await further developments in the limbo
“‘genera incertae sedis,” in company with its companion Laboulbeniopsis
on the same host described below, to which, despite a superficial similarity,
it seems also quite unrelated.

THAXTERIOLA Spegazzini—This name has been used by
SPEGAZZINI (Ann. Soc. Nat. Arg. 85:314) in a paper entitled
“Observaciones Microbidlégicas,” under the caption ‘‘ Anforomor-
fideas Argentinas,’’ to designate a series of very minute and simple
forms common on various insects, especially Staphylinidae, two
species of which were figured in my former paper (loc. cit., figs.
30-31), and referred to in the text (p. 250), no name being used to
designate them, owing to a lack of any complete knowledge of their
history and to their general insignificance. These organisms
consist primarily of two cells, the lower attached by a well defined
black foot, corresponding entirely with that of most Laboulbeniales;
while the upper, having become prolonged to form a necklike
termination, and having previously separated, at its base, a smaller
cell from which it is more often obliquely distinguished, produces
minute, naked, sporelike bodies formed in a single series and dis-
charged through the perforate extremity. These plants closely
resemble male individuals of Amorphomyces, among the Laboulbe-
niales; but their occurrence in large numbers, and under no other
form, precludes the possibility that they may be conditions,
or stages, of any member of this family. Whether, as in the sperm
cells of Amorphomyces, the spores produced by Thaxteriola are
formed continuously, as seems most probable, or cease to be pro-
duced after the protoplasm of the sporogenic cell has been exhausted,
I have not been able to determine satisfactorily. SpEGAzzINI, how-

1920] THAXTER—FUNGUS-PARASITES 15

ever, since in his generic diagnosis he says that “articulum su-
premum sporis amoeboidéis repletum,’’ appears to assume that
the latter supposition is correct. I have not seen the sporogo-
nium “‘sporis repletum,”’ and the usual appearance of the individuals
examined has been that shown in figs. 37, 38, the spores occupying
the upper portion of the cell and being arranged in a single series,
not irregularly disposed as in SPEGAzzINI’s fig. 5, and similar to
that which occurs in the closely related Endosporella described
later. It should be pointed out, however, that in the genus Laboul-
beniopsis, a description of which follows, and which appears to be
otherwise similar, a simultaneous formation of irregularly distrib-
uted spores appears to take place.

In order to facilitate a direct comparison between this type and
the others here considered, I append a description of a Javan form
that seems sufficiently distinct for ready recognition. Since they
are now known to occur on such diverse hosts as gamasid mites,
Forficulae, Hemiptera, and Coleoptera, it may be assumed that
numerous species of this group exist, none of them too well defined;
and it is probable that by the time systematists have finished with
them, posterity will have become burdened with a horde of these
uninteresting little plants.

Thaxteriola nigromarginata, nov. sp. (figs. 37, 38).—Subsigmoid,
pale brownish, except the clear hyaline base and apex; the distal
half edged with deep blackish brown, the suffusion broader toward
the middle. The basal cell including half the total length; its
extremity slightly broader than the distal half, the lower cell of
which is very obliquely distinguished from the upper, and is dis-
tinctly concave on its longer side, being also free from any blackish
suffusion. Total length 62-68 4; greatest width (distal portion of
basal cell) 8-8. 5 w.

On the hairs of a minute staphylinid, no. 2082, Sichavasne Java.

I am indebted to Jacosson for the host bearing this species, which
was found among a few beetles collected at Samarang. It seems sufficiently
well distinguished from the types usually common on Staphylinidae by its
slightly sigmoid outline, more slender distal half, the lower cell of which is
distinctly concave on one side when viewed laterally, by the very oblique
Separation between this and the sporogenous cell, and by the well defined
and rather clearly circumscribed black marginal suffusion of the latter, which
contrasts strongly with the adjacent hyaline areas. ‘

16 BOTANICAL GAZETTE [JANUARY

Two species of this genus have been described by SPEGAzzINI,
to one of which, 7. imfuscata, he refers the form represented in fig. 31
of my former paper, which represents an individual found on
Labia minor in Cambridge, and is distinguished by the fact that
the two upper cells are not separated by an oblique septum. His
second species, 7. subhyalina, which occurs on Aphodius, is said
to be distinguished by the fact that it is always hyaline, the neck
more strongly curved, and the basal cell relatively shorter.

A second genus of a similarly nondescript type has been named
Entomocosma by the same author (loc. cit., fig. 7, pp. 312-315). Al-
though possibly related to the present genus, its essential characters
are not at all clear. It seems in some respects similar to a prob-
lematical type, of which I have material collected at Waverly,
Massachusetts, in 1893, on Tachinus pallipes, and which I have
not subsequently observed.

It is to my mind very doubtful whether any close relationship
exists between these genera of “‘ Thaxteriolae,’”’ to which two others
are added below, and the “‘ Anforomorfas”’ with which SPEGAZZINI
associates them, and of which the Amphoromorpha entomophila of
my former paper may be taken as the type. As in the case of
Coreomycetopsis, however, their relationships to other groups are
equally obscure, and they must remain among the “genera incertae
sedis”’ until the discovery of further types which may possibly throw
some light on their affinities.

Endosporella, nov. gen.—Axis consisting of 4 superposed cells,
the basal attached by a well differentiated foot; the terminal one
spinose, separating uniseriate endospores aucined which escape
through a terminal pore.

Endosporella Diopsidis, nov. sp. (figs. 39-41).—Foot small,
black, and pointed; basal cell abruptly narrower and hyaline
below, the upper half becoming much broader and somewhat in-
flated distally, obliquely suffused with blackish brown. Second
and third cells much shorter, subequal, or the upper usually slightly
longer and broader; terminal cell a sporogonium, sometimes as
long as the rest of the individual, deeply tinged with blackish brown,
except the hyaline tip, which is primarily spinose and becomes
perforate, the upper half or more becoming filled with a simple

1920] THAXTER—FUNGUS-PARASITES 17

series of flattened superposed naked spores, which are successively
separated from the protoplasmic mass below. Apex opening
irregularly beside the large terminal spine, which seldom persists.
Total length 100-150 X 10-13 uw. Sporogonium 50-60 X 10-12 y.

On the terminal claws of the legs of Diopsis sp., nos. 2716, 2717, Kamerun,
West Africa.

This type is most nearly allied to Thaxteriola, from which it differs in being
4-celled, the sporogonium having no differentiated efferent neck, and dis-
charging broad flat spores. A majority of the individuals examined are
comparatively young, and only a few are beginning to form spores, so that in
this instance it is also impossible to say whether sporulation is a continuous
process or ceases after all the primary contents has been used. ;

Laboulbeniopsis, nov. gen.—Axis simple, consisting of a dif-
ferentiated foot, a 2-celled stalk, and a well defined terminal
sporogonium, at the base of which two cells are distinguished,
the rest of the cavity being filled with numerous minute hyaline
spores, which escape through a terminal perforation.

Laboulbeniopsis Termitarius, nov. sp. (figs. 42, 43).—Foot and
sporogonium pale brownish, the stalk nearly hyaline. Foot large,
externally strongly convex, a portion of its flat insertion deeply
blackened, more or less pointed below; the stalk much narrower, —
its upper cell shorter and broader than the lower. Sporogonium
as long as or longer than the stalk, straight, subsymmetrical,
slightly inflated below, tapering distally to the rather broad,
slightly flaring terminal pore, which is subtended by a scarcely
distinguishable constriction; the basal cells occupying the lower
fourth or less of the cavity, lying side by side, one slightly larger
than the other. Total length 100-130; sporogonium 45-50 X12 4;
stalk X8-10y; foot 25 X12m; spores 3.5-4X2-5 mM.

On tips of legs of Eutermes morio var. St. Luciae, Grand Etang, Grenada,

ok :

This form occurs very rarely, associated with Coreomycetopsis, of which
it was at first believed to be a stage or condition. The two, however, do not
seem to be related, although their general appearance is so similar. There is
not sufficient material available to determine the complete history of its
sporulation. As far as can be determined from the material available, the
spores develop simultaneously, filling the whole cavity of the sporogonium
above its two basal cells, and there is no evidence in the specimens examined
that successive periods of spore-formation occur, after the first are discharged.

18 BOTANICAL GAZETTE [JANUARY

In several cases the sporogonium has emptied itself, leaving a few residual
spores, and in such individuals the basal cells, as shown in fig. 42, are already
more or less disorganized, while the spores may be considerably swollen and
rounded, measuring even as much as 6X3.5 p, having surrounded themselves
with more or less evident walls.

Despite the apparently simultaneous formation of the spores, however,
and their irregular distribution throughout the cavity of the sporogonium,
it seems best, at least provisionally, to associate this type with Thaxteriola
and Endosporella in a group of “Thaxteriolae,” to which the genus Entomo-
cosma Speg. may possibly be added.

AMPHOROMORPHA Thaxter.—The type of this genus, A. entomo-
phila, was described and figured in my previous paper (loc. cit.,
p. 251, figs. 26-28), having been observed on species of Labia and
Diochus from the Philippines. It has since been noticed on a carabid
allied to Platynus from Jamaica, on a species of Pachyteles from
Verdant Vale, Arima, Trinidad, and on a host allied to Ardistomis
from Hayti. Although the specimens obtained from these sources
correspond in all respects with the original types, the more abundant
material thus made available furnishes certain additional informa-
tion which is of interest and tends to harmonize the characters of
this species with those of other related forms which are not dis-
tinguished by the same striking specific peculiarities.

An examination of specimens removed in toto, so as to include
the whole individual, including its attachment, and viewed anteri-
orly or posteriorly, shows that the foot, which, when viewed sidewise,
usually appears to be black and quite opaque and would naturally
be assumed to correspond to that of most Laboulbeniales, or of the
Thaxteriolae, is of quite a different nature. This is due to the fact
that its main mass consists of a secretion which spreads over the
surface of the host, and, when viewed in the position indicated, is
translucent, and may be transparent enough to show the actual
termination of the organism. This termination is very clearly a
short, abruptly distinguished rhizoid (fig. 45), which is held firmly
against the host by. the indurated secretion just mentioned, and
suggests the somewhat analogous rhizoidal attachments of some of
the Rhizideae among the Chytridiales.

An identical condition is seen in the other species of this type,
two of which are illustrated in figs. 44 and 46. The character of

1920] THAXTER—FUNGUS-PARASITES 19

the wall, its general appearance and texture, are also very like
some of the Chytridiales, and unlike that of the Thaxteriolae,
with which I was at first inclined to associate them. My present
impression, however, is that they have little if any relationship
to one another. There seems no reason to believe that they are not,
like the Chytridiales, strictly unicellular. Although their develop-
mental history is not, as yet, exactly known, it seems probable, from
an examination of the stages available, that the sequence of events
may be very similar to that seen in the temporary sporangia of
Cladochytrium Alismatis, for example. On the basis of this supposi-
tion the original cell may be assumed to divide completely into
spores, as has been the case in the individual of A. entomophila
(fig. 45). Figs. 26, 27, and 29 of my former paper, on the other
hand, may well be interpreted as illustrating different periods in
the spore discharge, which may be, in part at least, effected by
pressure exerted as the result of an intrusion into the sporogonium
of a new sporogenous cell, which may be assumed to fill the cavity
after the spores have effected their exit, and to become transformed
into another spore mass to be dischatged in a similar fashion. As
there is no indication that cilia are present on the spores, it is not
easy to see how otherwise the sporangium could be completely
emptied through so narrow an orifice. However this may be, it is
evident from the condition shown in fig. 45 that the generic diagno-
sis must be modified, no sterile basal cell being clearly distinguished.

It is also evident, however, that the true position of this type,
as well as the exact sequence of events in its development, have yet
to be accurately ascertained. I should not be reluctant even to
turn it over to the zoologists, although E. G. Racovirra, who has
figured a more simple type observed on crustaceans (Arch. Zool.
Exp. 1907-1908. pl. 10. fig. 26; 1908-1909. p. 272. fig. 2), speaks
of it as “une Laboulbeniacea parasite.’”’ Further references of this
nature, if they have occurred within the past few years, have
escaped my notice, with the exception of the account given by
SPEGAZzINI in the paper already cited, in which he described under
the name Amphoropsis three species: A. minutia on Hister, said to
be the same as that represented in fig. 29 of my previous paper;
A. subminuta on Echiaster, represented as somewhat more pointed

20 BOTANICAL GAZETTE ‘ [JANUARY

and sessile; and A. media, which is somewhat larger and more
distinctly stalked. Asecond genus, M yriopodophila, is also created,
with a single species, 47. argentina, the only basis for which appears
to be a slender habit. All of these 4 species are represented in the
figures as octosporic, although this character is not mentioned in
the text. I should personally be reluctant to separate either of
these forms from Amphoromorpha, and the species of Amphoropsis
are certainly congeneric with the types illustrated in figs. 44 and 46.
Since the material of the species represented in fig. 44 is sufficiently
abundant and has been observed on two different genera of roaches,
it seems worth while to append a description, although all the
individuals examined are at the same point of development, the
sporogonia being completely filled with spores.

Amphoromorpha Blattina, nov. sp. (fig. 44).—Yellowish, seacile.
with a large dark foot. Form elongate oval, somewhat broader
distally, the apex rounded. Spores between 50 and 100, about
5 in diameter. Total length of sporogonium 55- 70 X 18-20 M,
exclusive of the foot, which is 18-22 X18 yw, seen in front view.

» On the axis of the antennae of a dark wingless and a pale winged blattid,
nos. 2938 and 2939, Grand Etang, Grenada, B.W.I.

This species is similar to A. media in size, but differs in its form, its sessile
habit, and its much more numerous, smaller spores. It is apparently confined
to the axis of the antennae, where it grows among, but not on, the hairs. A
second species inhabiting the hairs, and not the axis, was found in the same
locality on a different host, and i tedin fig. 46. This form is character-
ized by a somewhat different shape, its smaller size, and transparent, hardly
suffused, foot.

ASTREPTONEMA Hauptfleisch, Ber. Bot. Gesells. 13:83. pl. 8.
1895.—In a paper entitled “ Astreptonema longispora, n.g., n. sp.,
eine neue Saprolegniaceae,’’ HAUPTFLEISCH has described a pe-
culiar organism which grows attached to the chitinized end of the
rectum of Gammarus locusta, consisting of a simple, unicellular,
multinucleate filament, attached at its base, and distally producing
a series of successively formed spores, or rather of spore mother
cells, within which single definitely walled spores are formed, at
first uninucleate, and later containing as many as 8 nuclei. These
spores are formed in large numbers and are eventually freed by

1920] THAXTER—FUNGUS-PARASITES Ess ge
the disorganization of the mother cell walls. .The filament is
attached at the lower end, the wall of-which is at first thickened,
the thickening organizing a well developed and peculiar sucker-like
structure, which forms a definite organ of attachment. The walls
of the filament mother cells and spores are comparatively thin,
although well defined. As the title indicates, this type was regarded
by HAvuPTFLEISCH as unquestionably belonging to the Saprolegnia-
ceae, with a possible relationship to Aphanomyces; the mother
cells, despite the absence of any signs of antheridia or of zoospo-
rangia, being regarded as oogonia, and the contained spores as
oospores, a comparison being drawn between them and the seriate
oogonia, of Saprolegnia monilifera DeBary. The author’s con-
ception of the type is summed up in his “kurze lateinische Diagnose
fiir diese neue Saprolegniaceae,”’ which reads as follows: ‘“Thallus
non racemosus. Una tantummodo ovospora in ovogonio nata,
quasi explens ovogonium. Ovosporae plurium nuclearium ob-
longae, 2—-2.6X7-10u. Ovogonia terminalia semper simplici serie
adnexa, aliud alii, non transfusa. Sporangia incognita. Anther-
idia desunt.’’ Saccarpo in the Sylloge (14:446) places this type
among the Chytridiales, but neither author appears to recognize
the fact that it has any relationship to the Enterobryae, to which
it undoubtedly belongs. The only character which might separate
it from the type genus Enterobryus is found in the presence
of definitely differentiated spores, which replace, or succeed, the
terminally abjointed segments which are characteristic of all
the species of this genus; but whether this character should be
regarded as separating the two types generically, or as extending
our knowledge of the little known life cycle of the last mentioned
genus, it is not at present possible to decide. In the numerous
forms of Enterobryus which I have examined, none that have been
observed growing within the intestine of the host have shown a
development of well differentiated spores; although the terminally
abjointed segments may be more or less sporelike, according as
they are longer or shorter. It does not seem possible, however, to
homologize them closely with the spores of the form described by
HAUPTFLEISCH, or with those of the new form described later.
It is nevertheless quite possible that, as in many cases among the

22 BOTANICAL GAZETTE [JANUARY

higher fungi, certain species of the same genus may be sporiferous
in a special way, while others are not; or that differences in en-
vironment may bring about the sporulation of species which
normally reproduce by separated segments only. In the two in-
stances under consideration, for example, the individuals do not,
like most species of Enterobryus, grow submerged in the more or less
fluid contents of the ventriculus, or smaller intestine, in which
the food ingested by the host has only partially been digested;
and while the species of HAUPTFLEISCH is attached just within
the anus, the new form is found growing on the hard external chiti-
nous plates about the opening. As far as the possible food relations
of these two forms is concerned, the situation seems to be quite
different, since they come in contact with fecal matters only, which
might be supposed to exercise a definite influence on their course
of development. It should be mentioned, however, that although
I have, in one instance at least, obtained abundant material of
what appear to be several species of Enterobryus growing outside
the anus of a Passalus from Grenada, B.W.I., none of the indi-
viduals, although they are otherwise very similar, show the sporu-
* lation which is so conspicuous a feature in the new form to be
described.

This form is characterized by the possession of a huge basal
cell; its very thick wall often laminate above, filled with a coarsely
granular protoplasm, and attached at its base by a well developed
sucker-like attachment entirely similar to that of other species of
Enterobryus. The primary axis is at first continuous (fig. 47a),
but later a terminal segment of considerable length is separated,
and at least one more may be similarly formed, as in fig. 47),
in which a terminal scar shows very clearly that a segment of this -
sort has previously been abjointed. Such a condition, were it
found within the intestine, would inevitably be regarded as belong-
ing to some species of the genus Enterobryus. After one or more
of these segments has been abjointed, and as a result of the activity
of the denser multinucleate protoplasm at the end of the cell below
the scar (fig. 51), a series of flattened cells begins to be cut off, each
of which is supplied with a single large nucleus. Soon after these
cells, or spore-segments, have been separated, they become ab-

1920] THAXTER—FUNGUS-PARASITES 23

ruptly compressed, so that above the fourth or fifth cell, as a rule,
the series, when viewed edgewise, is thin and flattened, as is shown
in fig. 47. The cells appear to be spore mother cells, within which
thin-walled, sausage-shaped spores are firmly held by the thickened
sheath which surrounds them and is continuous with the wall
of the basal cell from which they were originally separated. As
far as can be determined from the material available, these spores,
which become eventually multinucleate, are separated by the
breaking off of the whole or a portion of the series, and are not
set free individually, as seems to be the case in the thin-walled
species described by HAupTFLeiscH. What the further history
of their development is cannot definitely be stated. _ It seems
probable that the spore groups are ingested by the xylophagous
host, together with other spores of fungi which are present on their
natural food, and that, separating as a result of the action of
digestive fluids, they either pass through a preliminary period of
growth attached to the wall of the digestive tract, or, in being voided
with the excrement, become attached and develop at the mouth
of the anus.

Although this species differs in its very thick walls, and in the
form and more or less permanent association of its spores in series,
its characters seem to correspond in all essential respects with those
which are said to distinguish Astreptonema. Fig. 10 of Haupt-
FLEISCH’s plate would indicate that his species is characterized
by the separation of one or more terminal segments, which precedes
the formation of spores. That these may be antheridia, as he
Suggests, seems quite improbable, and since, as he states, his
material was somewhat scanty, it may prove that in this respect
as well as in others the two show a very close correspondence.
The cytological characteristics seem to be identical. The nuclei
in both are large and rather numerous in the primary cell, more so:
in the denser contents of the distal region, where the spore segments
are cut off (fig. 51), there being fewer toward the base, although
one seems to be almost always present just above the foot (fig. 49).
This foot is entirely similar in both and identical with the corre-
sponding organ of Enterobryus; and the spores, although differing
in shape and method of association when mature, are produced in a

24 BOTANICAL GAZETTE [JANUARY

similar way within mother cells. There can be little doubt as to
the generic identity of the two forms, yet their characters are so
similar to those of Enterobryus that I have preferred to use this
generic name, in view of the fact that in no instance has the com-
plete history of a species of this genus been satisfactorily observed.

Enterobryus compressus, nov. sp.—Hyaline to pale dirty
yellowish. Basal cell very large and thick-walled, somewhat
broader distally, 500-850 28-35 u, straight or usually slightly
curved at the base, attached by a well defined, slightly brownish
yellow foot, shaped like an inverted cup, and distinguished by a
slight constriction from the basal cell, which bulges more strongly
on one side above it. Segments separated from younger specimens
about 200X184, their formation followed by the production of
spore mother cells which are formed at the distal end of the basal
cell, the series above the fourth or fifth cell becoming broad and
flat through compression; the cells about 8 long by 35 u broad
by 18 thick, each containing a single spore which nearly fills the
cavity, surrounded by a thick sheath continuous with the wall
of the basal cell.

Growing wholly exposed on the anal plates of a large species of Passalus,
Dominica, B.W.I., no. 2170, oh

The iaifadually thick walls of this species and the coherence of its spore
mother cells no doubt are influenced by its aerial habit, as a result of which
it may be exposed to very dry conditions. The individuals represented in
fig. 47, with two exceptions, are very old, and seem from the broken outline
of their distal ends to have already shed a portion of the spore mother cells.
In a majority of the sporiferous individuals, however, it is possible to dis-
tinguish the scar clearly shown in figs. 50, 51, from which it may be assumed
that a segment has been separated, such as is shown in fig. 47). A large
number of Enterobryae have also been obtained growing in the same position
on a species of Passalus from Grenada, which seems to include more than one
species, the larger of which resembles the present form in all respects, except
for the absence of any sporulating individuals. All of these, although their
walls are somewhat thicker than is normally the case, would be referred without
hesitation to Enterobryus.

The nuclei ore in figs. 48 and 51 are readily uatuet’ in the alcoholic
material by d g, after staining with Haidenhain’s iron alum haematoxy-
lin, The AE? shown are entirely similar to those described by HaAurt-
FLEISCH, and serve to show that these plants cannot under any circumstances
be related to the higher bacteria, as has been suggested. One may admit that

'

1920] THAXTER—FUNGUS-PARASITES 25

they must be placed among the Phycomycetes; but they appear to occupy a
very isolated position, and it is difficult to agree with this author that they
have any close relation to the Saprolegniaceae.

In regard to their relation to the host, it may be said that the aerial habit
of the present form seems to exclude the theory that these plants are purely
commensalists, since they can only come in contact with the voided feces; and
this fact, taken in connection with their highly specialized sucker-like attach-
ment, suggests that they may be, to some extent at least, truly parasitic. :

HARVARD UNIVERSITY.

CAMBRIDGE, Mass.

EXPLANATION OF PLATES I-V

The figures are reduced from camera drawings made with Zeiss dry ob-
jectives and eyepieces and Leitz water (no. 10) and oil (1/16) immersion as °
saan

Enohesaaet: chilensis Thaxter

Fic. 1.—Portion of host greatly magnified, showing distribution of peri-
thecia.

Fic. 2.—Mycelium associated with perithecia; 10, mu

Fic. 3.—Three perithecia among spines on host; D, 2.

Fics. 4+5.—Ascus and ascospores; 1/16, 18.

: Termitaria coronata Thaxter
Fic. 6.—Young individual showing preliminary stage; subdiagrammatic;

14.

Fics. 7-8.—General appearance of mature fungus growing on leg and tho-
rax respectively ;former showing blackened primary attachment which shows
through hymenium in center; D, 4.

Fic. 9.—Habit of growth on host; X25.

Fic. 10.—Section of mature sporodochium, showing hypertrophied cells
of host below chitinous asap dark line of primary thallus shown,
succeeded by f t region, showing two primary
zones, in upper of which a rc oh Aen into two zones is indicated;
sporodochium penguins: by two hairs arising from integument of host; semi-
diagrammatic; D,

Fic. 11 and seen from above, showing distribution of toothlike
projections from sporophores; 1/16, 12.

1G. 12,—Sporophores with included spores; semidiagrammatic; 1/16, 12.

Termitaria Snyderi Thaxter
Fic. 13.—Portion of preliminary stage, showing margin and chlamy-
mati, - 4.
4.—Portion of section of old individual, showing hypertrophied
cells oh hat below slightly intruded primary attachment, blackened primary

26 BOTANICAL GAZETTE [JANUARY

layer, with a few chlamydospores in situ, fundamental layer, and above it
sporogenous region, comprising two zones, lower distally blackened; 10, 4.

Fic. 1 £ .—Sporophores seen end on, showing terminal perforation; 1/16, 12.

1G. 16.—Sporophores seen in section, showing origin from cells of funda-

mental ‘aie spore, and terminal perforation; 1/16, 12.

Fic. 17.—Free spores; 1/16, 12.

Muiogone Medusae Thaxter

Fic. 18.—Young spore developing from proliferous end of old sporo-
phore; 10, 4.

Fic. 19.—Later stage of young spore of third order resulting ining prolif-
eration of second order; 10, 4.

Fics. 20-21.—Older primary spores; 10, 4.

Fic. 22.—Spore showing origin of terminal appendages; 10, 4.

Fic. 23.—Mature spores, appendages bearing a few secondary spores;
10, 4.

Fic. 24.—Portion of appendage with secondary spores; 10, 18.

Fic. 25.—Group of spores in different stages of development.

Muiaria curvata Thaxter

Fic. 26.—Single plant bearing two mature spores drawn in outline; D, 4.
1G. 27.—Single spore seen in surface view; D, 4.
Muiaria fasciculata Thaxter
Fic. 28.—Single spore seen in surface view; D, 4
Fic. 29.—Single plant with several spores in different stages of develop-
ment and numerous sterile filaments; D, 4.

Aposporella gracilis Thaxter “®
Fic. 30.—Two plants on wing of fly; D, 4
Fic. 31.—Two branches, one unbroken, ihe proliferous.
Coreomycetopsis oedipus Thaxter
Fic. 32.—Young individual of unmodified superposed cells; 10, 4.
Fic. 33-—Young individual, division beginning in an intercalary cell; 10, 4.
Fic. 34.—Mature individual in which septa above intercalary cell have
disappeared, forming continuous cavity within which spores are being ab- —
jointed; 10, 4.
Fic. 35.—Younger individual in which terminal cells are beginning to
disorganize, 4 septa still remaining above sporogenous hyphae; 10, 4.
Fic. 36.—Spores separated by crushing; 10, 12.
Thaxteriola os afin ck gncte Thaxter
Fic. 37.—Mature individual; 10, 4.
Fic. 38.—Two individuals im situ on spine of host, left one turned to
show partly posterior view; 10, 4.

BOTANICAL GAZETTE, LXIX PLATE I

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THAXTER on FUNGUS-PARASITES

PLATE II

BOTANICAL GAZETTE, LXIX

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AXTER on FUNGUS-PARASITES

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THAXTER on FUNGUS-PARASITES

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GAZETTE

BOTANICAL

PLATE IV

BOTANICAL GAZETTE, LXIX

THAXTER on FUNGUS-PARASITES

PLATE V

BOTANICAL GAZETTE, LXIX

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THAXTER on FUNGUS-PARASITES

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1920} THAXTER—FUNGUS-PARASITES 27

Endosporella Diopsidis Thaxter
IG. 39.—Young individual in which sporulation has not begun, although
seriniaal mR has been broken off; 10, 4. j
Fic. 40.—Older individual, spine persistent and sporulation beginning;

As

¥ IG. 41.—Mature individual, distally perforate; 10, 4.
Laboulbeniopsis Termitarius Thaxter _
Fic. 42.—Mature individuals, basal cells of sporogonium disorganized,
a few residual somewhat swollen spores remaining; 10, 4.
Fic. 43.—Mature individual, spores beginning to escape; 10, 4.
Amphoromorpha Blattina Thaxter
Fic. 44.—Front view of mature individual removed in toto from antenna
of host, showing unevenly spreading secretion over simple rhizoidal foot; 10, 4.
Amphoromorpha entomophila Thaxter
IG. 45.—Base of mature individual completely filled with spores and with
no large basal cell, showing rhizoidal foot and secretion as in preceding figure;
10, 4.
Amphoromorpha sp.
Fic. 4 6—Two individuals growing on antennal hair; foot seen laterally,
but visible through transparent secretion; 10, 4. .

UPLAND SOCIETIES OF PETOSKEY-WALLOON LAKE
REGION

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 256
H. D. CLAYBERG
(WITH ONE FIGURE)
Introduction

The writer became familiar with this region through spending
the summers there for the past 12 years. During this time the
rapid destruction of the few wild areas left suggested that studies
be made while natural remnants were still available. The observa-
tions on which this paper is based have been carried on for at least
three years. Besides the general data, 40 quadrats were made and
a map of the plant geography (to be published later) was drawn.

The topography of this area was largely determined during the
Pleistocene and Postglacial. LrvrrEetr and TAytor (16, 17) have
covered this, phase ably. At the time of the formation of Lake .
Chicago beaches this region was ice-bound, later forming part of
the submersed area which gradually emerged as the waters changed
from Lake Algonquin to the Nipissing Great Lakes, and through
the Post-Nipissing stages to end in Lake Michigan. This periodic
subsidence left the Algonquin, Nipissing, and later beaches (to-
gether with scattered morainal lakes inland), but erosion here has
eaten away much of the Post-Nipissing levels.

The region at present is underlaid with Devonian deposits.
Inland the surface layer is Upper Devonian, being largely black
Antrim shale; while a marginal strip of about 3 km., from Petoskey
west, and all territory north of the south margin of the Inland
Route are covered with Middle Devonian. The latter contains the
Petoskey limestone, which outcrops along the shore of Little Trav-
erse Bay, either as shelving bedrock or limestone cliffs, the beds
dipping inland. The lakes and channels have a layer of sub-
aqueously deposited sand, covered in most places by black muck
(fig. 1).

Botanical Gazette, vol. 69] {28

1920] CLAY BERG—UPLAND SOCIETIES 29

The region studied lies in Emmet and Charlevoix counties,
Michigan. It includes a strip about 2 km. wide along Little
Traverse Bay from Bay Shore to Idylwilde, together with Walloon

LAKE
MICHIGAN

Lenny

Fic, 1 i

Lake and surrounding shores. Bear Creek and Resort townships
in Emmet County are also included.

' The area of the region exceeds 260 sq. km. (about 100 sq. mi.,
of which about four remain in forest) and includes four upland

30° BOTANICAL GAZETTE [JANUARY

masses, one between Pine and Walloon lakes, another between
Bear Valley and Walloon Lake, a third between the latter and the
Inland Route, and a fourth north of the Inland Route. Inland
Route is a valley extending from Kegomic to Cheboygan, with a
continuous water channel running through it, beginning with
Round Lake on Little Traverse Bay and emptying through Cheboy-
gan River. While the only river of any size is Bear River (flowing
through a broad and deep valley northward to Petoskey), many
small creeks empty into the lakes and into Lake Michigan.

The topography is irregular and hilly, the upland being mostly
highest behind the Algonquin bluff, sloping gradually down to the
southeast in the territory south of the Inland Route, and to the
northeast in the portion north of the same. The varied glaciated
topography suggests wide floristic diversity, combined with youth-
ful form (6), and this is the actual state found. The region was
entirely covered with forest before settlement; the uplands with the
climax maple-beech forest of the region, and the channels like the
Bear Valley, together with the swamps and creek valleys, being
mostly a continuous stand of Thuja occidentalis L.

The classification of CowLEs (5, 6) has been found more suitable
in analyzing the formations of the region, but this may partly be
due to the fact that less soil diversity was observed than found by

WHITFORD (25) along Lake Superior, so that an edaphic arrange- . |

ment seemed less desirable. The edaphic factor, however, could
not, be excluded, as in cases where one type of soil alone was studied
(9, p. 46). Coons divides his successions into swamp (lagoon>
forest) and sand (beach-pine barren) series (20, p. 60).

Upland types preceding climax

The upland societies remaining include only the late tree stages,
the earlier ones being lost. For convenience of treatment similar
areas in the older parts of other series will be discussed here. Three
apparent stages are seen.

PINE FOREST

Only Pinus Sirobus L. and P. resinosa Ait. occur. P.Banksiana

Lam. has not been found, although it occurs around the south end

1920] - CLAYBERG—UPLAND SOCIETIES i, @ te

of Lake Michigan, and in the pine barrens of northern Michigan
as near as Wolverine in Cheboygan County. In general, the pine
occurs in three places: (1) on the high hills back of Walloon Lake,
(2) on Algonquin and Nipissing bluffs, and (3) as an early stage in
dune forest succession.

The first location is a xerophytic open society of red pine sloping
southward to the lake. The herbage below is dominated by ericads
such as Gaultheria procumbens L. and Vaccinium vacillans Kalm.
Occasional artificial clearings show an apparently succeeding stage
whose components are crowded and mainly of shrub size. Here
Cornus (Baileyi ?) and Viburnum acerifolium L. dominate. Follow-
ing this is an obviously secondary society (may be absent in the
primary series), taller than the preceding one and primarily Betula
alba L. var. papyrifera Spach., with a mixture of Populus grandi-
dentata Michx. and P. tremuloides Michx. Oak seems to follow.

The second type, almost entirely white pine, shows the oldest
pines seen, growing on slopes approaching 45°, with sparse vegeta-
tion below characterized by Solidago racemosa Greene and Shep-
herdia canadensis Nutt. The xerophytic conditions here obtaining
are indicated by leaves of Aralia nudicaulis L. 12 cm. across and
to cm. tall, as well as by beds of Polytrichum commune L. Where
cleared, the succeeding thickets are white birch with some Prunus
pennsylvanica L. f. and Amelanchier.

e third type is a mixture of the two species, with white pine
dominating, but with other conifers present. Among the par-
ticularly characteristic undershrubs occurring are Corylus rostrata
Ait. and Rosa acicularis Lindl., while the herbage is largely of the
ericoid type. At Menonaqua the full series is seen, but north of
Harbor Springs erosion has eaten back into the pine society; the
xerophytic conditions resulting permit persistence of much of the
dune flora (telescoped succession).

As at present limited, pine occurs here near water in positions
exposed to direct wind and of noticeably xerophytic nature. This
agrees with its probable status as a relict tree formerly covering the
upland. TransEav (24) believes conifers reached their present
SS in the lower peninsula of Michigan by way of the lake
shores. é

32 BOTANICAL GAZETTE [JANUARY

OAK FOREST

Quercus rubra L. furnishes an unimportant and rare type.
Stands are seen near Walloon Lake, and on the Algonquin bluff
north of Harbor Springs, which extend inland'in places for some
distance. This tree occupies the same sort of habitat as the pine,
and probably succeeds the latter in certain areas. Oak also covers
Harbor Point, a low Post-Nipissing area. The discontinuous dis-
tribution shown suggests relatively recent seeding at Walloon Lake.
Along the bluff north of Harbor Springs oak succeeds pine, when
trees of the former are near and the pines are far enough apart
(or have been cut or burned off). This occurs especially where the
slope is not steep. Invasion of the adjacent upland by oak has
occurred in one place (5). Quercus velutina is absent from this
region (13).

HEMLOCK FOREST

The few stands of Tsuga canadensis Carr. left are confined to
areas similar to those bearing pine, but of less xerophytic nature.
It appears that any area bearing hemlock in this region is eco-
logically prepared for the climax forest, for, aside from the fact that
hemlock is more or less common in the climax forest itself, and that
hemlock stands normally bear some deciduous trees, the under-
growth and seedlings of an open hemlock forest are usually decidu-
ous, and where the trees are cut off the young growth is largely
maple and beech. The periodic reproduction of conifers may have >
a disadvantageous influence on their persistence. On the low
hills bordering Walloon Lake a nearly pure stand is common, run-
ning from an average of 20 cm. diameter to a maximum of 80 cm.
In such a primary society few herbs or seedlings are scattered over
the brown needle layer. The characteristic plants are Taxus
canadensis Marsh, Lycopodium lucidulum Michx., L. clavatum L.,
Clintonia borealis Raf., and Mitchella repens L. Where cut off,
the sapling flora is almost exclusively deciduous, being about 60 per
cent Acer saccharum Marsh, mixed with Fagus grandifolia Ehr.,
Acer pennsylvanicum L., and A. spicatum Lam.

Beyond Menonaqua the pines adjoin a hemlock beech society,
which very likely will succeed them. This represents the richest

1920] CLAVYBERG—UPLAND SOCIETIES 33

hemlock type seen, probably because farthest from the shore and
most sheltered from the wind. The presence of many balsam and
some oak seedlings, and the absence of sugar maple, make the next
stage uncertain. Dense thickets of Corylus rostrata Ait. and much
Taxus are characteristic. The hemlock on a Post-Nipissing level
west of Harbor Springs is similar, but is mixed with Abies balsamea
Mill. and Thuja occidentalis L. The Algonquin cliff west of Petos-
key in several places bears large hemlock stumps of uniform (71—
75 cm.) diameter, indicating that it was once largely occupied by
a fine hemlock forest. The trees were cut sometime ago, for the
secondary forest is nearly grown (average diameter 25 cm.), being
beech, sugar maple, and Betula lutea Michx. f. A constant associ-
ate on open banks and cliffs is Polyirichum commune L., taking here
as prominent a place as Taxus canadensis does in the level and denser
part of the forest.
Climax forest
SERIATION

The composition of the climax primary forest of the region has
long been considered constant from the time the maple and beech
reach dominance and respectable age. ‘This is true floristically,
but not ecologically or physiologically; for a climax formation
is static in species, but dynamic as to individuals. Analysis of
sufficient territory shows the forest to be more or less of a patch-
work composed of trees in varying stages of development.

Cooper (4) found the climax forest he studied to be a “complex
of windfall areas of differing ages, the youngest made up of dense
clumps of small trees, and the oldest containing a few mature trees
with little or no young growth beneath, those of a single group being
approximately even-aged. This mosaic or patchwork changes
kaleidoscopically through long time spaces, but the forest as a whole
remains the same, changes in various parts balancing each other.”
His studies were of a coniferous forest. The climax here is decidu-
ous, so differences are to be expected. The forest floor is lighter and
the next generation starts sooner in the case of the maple-beech
forest. The patches observed in the climax forest of this region are
too large to consider as the result of one tree fall. Further, they

34 BOTANICAL GAZETTE [JANUARY

would all have to approach the oblong or elongate form, whereas
they are irregular where discernible, for the maple-beech forest is
not to be considered as either patches of cleanly distinct even-aged
trees, or as continuous forest with each generation even-aged
throughout. It rather varies between these two ideals as limits.

Since the seriation is of individuals, the climax is not final, but
recurrent, and during the development of each rough area or patch
certain ages are to be recognized, each with fairly definite form,
height, and spacing. At any one locality they follow each other in
regular order, two or more commonly superposed, and adjacent
areas independent of each other.

Definition of these ages is attempted approximately as follows:

Age Average diameter Average spacing Average height No. per 1oosq.m.

Seedling. ...... I 5 mm. 4o cm 40 cm 670
Sapunes <6. 6 3 2 cm. 65 cm 4m 300
Young adult 3 15 cm. 3m om 10
pT, Senna are 4 50 cm. 6 m. 30m 3
Old tree... 5 65-85 cm. 8-20 m. 35-40 m. I

ECOLOGICAL LIFE HISTORY.—The flowers and fruits of the
climax forest are mostly inconspicuous. Undeveloped fertile seeds
are always present, as is shown by_ the abundant germination in
clearings. The latter also emphasizes light as a critical factor.

Since the forest determines the intensity, amount, and continuity
of the light penetrating, the number of seedlings (age 1) and their
distribution depend largely on the forest’s age. Many seedlings
die, but are easily replaced. ‘They seem rare, but in reality often
average 7 per sq. m., forming a scattered layer 20-60 cm. in height.
The typical seedling form shows a slender, often branched,
stem. ‘The leaves are loosely corymbed or in one or two horizontal
layers. The oval foliage outline results from free lateral growth
(perhaps also spread to catch maximum of light). Apparently
most of them remain nearly stationary for years. The taller ones
appear distorted and dying, as if starved for light, which seems
to decrease approaching the base of the sapling foliage.

Removal of the old trees above (15) permits freer elongation of
the saplings. The seedling stratum becomes better lighted and
watered, due to recession of foliage above and roots below. -More

1920] CLAYBERG—UPLAND SOCIETIES 35

seedlings germinate to fill the gaps, and elongation results in the
formation of a new sapling stand (age 2) as the trees above reach
age4. The sapling axis is long and straight, forks and side branches
equaling the stem are rare, and the foliate part of the tree, although
polygonal in cross-section, approaches a right cylinder. The
lowest branches are dead twigs, the later ones are horizontal or
angle up.

A fine close sapling stand 4 is the culmination in percentage of .
volume occupied. As the size of a stand increases, the distances
between its trees increase also, and it is believed that a law will here
be found to control relation of diameter and spacing of trees. The
sapling age shows maximum increase in size for given decrease in
number per unit area, hence competition between trees of equal
age is keenest here.

With removal of another generation the saplings elongate, but
intensity of vertical growth decreases, for the relatively open
Spacing permits lateral growth and reapproach to the typical
broad form shown by isolated trees in field and pasture. In passing
from the second to the third age a transition in branch form is seen,
from the filiform type of evanescent branch to the massive type of
permanent branch characteristic of the adult. These originate far
above the sapling tops and hence are developed later. Comparison
of the young adult and sapling stages with regard to ratio of height
to breadth suggests partial etiolation in the latter. All saplings
with forked axes are eliminated, since no adults are seen with forks
at sapling level. Naturally a biaxial shoot is at a disadvantage
under active competition with those supporting but one.

With further thinning of population the adult stage (age 4) is
teached. This is the true ecological climax. The maximum foliage
display and culmination of vitality are seen here. A typical tree was
studied, felled, and measured. There was no sign of lost branches
or decay, all branches bearing a rich display of leaves in normal
position. The trunk was clean, straight, and subcylindric, with
the lowest branch 2 5.3m. from the ground. The diameter basally
was 53 cm. and the tree was 32.5 m. tall. The crown was oval,
with 12 major branches. The duramen showed a central cavity
8 cm. wide at the base, with its cone point ending about 2 m. above

36 BOTANICAL GAZETTE [JANUARY

ground. Because of this cavity the age could only be estimated by
proportion; the tree was approximately 250 years old (allowing
for thicker early rings).

The senile or last stage (age 5) is scattered, because definite
spacing is lost. Many primary limbs are gone, adventitious
branches along the trunk and on otherwise dead limbs and stubs tak-
ing up the work. The heartwood is largely rotted. The sawed-off
stump of one very old tree showed a cross-diameter of 120 cm.,
but only a margin of 15 cm. around the outside was wood, the rest
being hollow. The base, at or near ground level, is often inhabited
by a colony of big ants, and the breaking point is normally at this »
place. A certain degree of pliability is still retained in ages 4 and 5.
The latter are apt to sway widely in a wind, some creaking loudly
also under the strain; yet the tree may stay thus at the verge of
fall for years.

Approach of death is equally indicated by the crown where
symmetry is lost by branch fall. The top of an old tree is always
ragged. These trees attain the maximum of height and diameter.
They represent a wider range of age, dimensions, and form than
any other of the life stages, partly because of their liberty of freer
development than the younger trees below. -

The beech follows the maple in general, but it is stockier,
broader, and shorter, reaching each age much more quickly. Its
terminal bud is weaker, and the tree apex is often injured by falling
trees, lightning, and other destructive agents, so that the nutrients
go to several branches near the top. As a result it is strikingly
deliquescent and rarely develops a bole over 15 m. in height below

the branches.
STRATIFICATION

MAXIMUM COMPLEXITY.—Investigators in the tropics have |
noted 5-7 strata in the rain forest (21). These were primarily due
to the leafing out of the various tree species at different levels. It
has been assumed that little or no stratification occurred in the
climax maple-beech forest, the belief being partly based on the
poverty of tree species (but two or three important) and the far
lower degree of luxuriance as compared with the tropical rain
forest.

1920] CLAYBERG—UPLAND SOCIETIES 37

Soil stratum: here lie roots, youngest farthest up.
Lower forest... - fea stratum: thin crisp continuous layer
Herbage stratum: includes seedlings also oe 1).
Sapling trunks: first really open stratum; shrubs here.
Middle forest... . (Death stratum: layer of dead twigs below sapling foliage.
Sapling synfolium: sapling foliage layer.
ee trunk stratum: ample light first reached.

U forest...
pper fores Upper synfolium: broken zone of adult tree foliage.

The strata of any one generation are best shown and fullest
developed at the sapling age. They are not so well formed in the
seedling and are breaking down in ages 3 to 5. Only major layers
are listed. For this reason the seedling synfolium is not accorded
separate rank (although thicker than leaf stratum).

SYNFOLIUM.—The synfolium is the layer formed by leaves of
trees of the same age. It is the result of photosynthetic need in
crowded sessile individuals. It must be dealt with not only as
compound, with the unit the foliage leaf, but also as a mass. The
placing together of all the synthetic tissue of a group of trees is of
serious ecological importance. The leaf placing, together with the
crowding of the trees, makes the vertical section of an individual
show a nearly rectangular foliage mass. The synfolium governs
its depth by means of the light relation. It also controls the amount
and composition of the herbage below. In the general discussion
here given, the synfolium of the sapling is taken as type.

While the synfolium continually and gradually ascends as the
trees grow (no sudden jumps), the history of the foliage layer shows
characteristic stages. Since the seedlings are scattered, their |
foliage layer is discontinuous horizontally. It is very close to earth
level and is but 20-40 cm. vertically. As the sapling age
approaches, the small foliage masses fuse into a continuous layer,
having a much greater vertical section, and both upper boundaries
parallel, horizontal, and nearly flat. This is the ecologic climax
of the synfolium; here it reaches its greatest definition and density.
Most of the growth is strictly limited to the top at this age, but
later ages show the maple in its true light as more typically a
deliquescent tree.

At the sapling age the synfoliar depth (from its top to its bottom)
is 3-4 m. As it recedes from the ground its upper surface becomes

38 BOTANICAL GAZETTE [JANUARY

uneven and covered with the free cones of the young adults, while
spaces creep up from below. ‘These result because lateral growth is .
insufficient to maintain closure. Increased lateral spacing now
permits increased lateral growth, one of the prime factors slowing
vertical elongation. Approaching the adult stage (age 4) the layer
breaks up into its component tree masses. This occurs by rifting
(vertical or horizontal breaks due to tree or branch fall), the gaps
becoming nearly unfillable at age 3, for closure is either by elonga-
tion of a younger tree or by lateral growth of the adjacent tree
circle. This age is the first one free vertically and laterally.

A further step is the breaking up of a tree unit into foliage
clumps, one or severaltoa branch. Finally, many of the oldest lose
all primary foliage, the trunk and branches bearing scattered hand-
fuls of leaves. This secondary foliage is borne on slender twigs
developed from adventitious buds. Gradual fall of the last age
destroys all semblance of a foliage stratum.

Recession occurs in two main ways (trunk elongation unimpor-
tant): by shedding of leaves and branches at the synfolium base (the
synfolium is self-pruning during the growing season), and by apical
growth, the stems adding new leaves and branches, thus extending
the synfolium compass vertically. With increase of synfoliar dis-
tance (from ground) and rifting, the herbage layer receives increas-
ingly stronger light; thus the tree seedlings are stimulated to more
active growth and the illumination of the forest floor decreases again.

The sapling synfolium contrasts with the trunk strata above
and below, in apparent space occupied, color, and opacity. The
lighting of the trunk stratum above is much greater, and that
of the dead branch layer much less, being composed of flat, thin,
horizontal tissue plates. The synfolium seems to have the ideal
structure and arrangement for maximum of surface, light absorp- —
tion, synthetic efficiency, and carbon dioxide use, together with the
minimum material, volume occupation, and transpiration. The
apparent effect on the eye gives impressive display and exaggerated
idea of solidly filled space. This effect is heightened on passing
from the bright sunlight into the dense shade of the forest.

Yapp (26) makes some interesting observations on evaporation —
at different levels in an English marsh, and SHEerFF (22) on an

1920] CLAYBERG—UPLAND SOCIETIES 39

American marsh, finding evaporation rate proportional to height
above the soil. These suggest that data on the levels of the climax
forest of this region would be significant. Gates (8) compares
evaporation at the chamaephytic layer in different societies but
not at different levels. He believes evaporation a result, not a
cause, of succession.
ENVIRONMENT

Competition is affected by several influences: physical and
chemical factors, parasites, and individuals of the same or an
older generation. Scattered among the herbage are tree seedlings,
many of them dead or dying. In fact the younger the group, the
more die. No competition between seedlings occurs except as
two are found within short radius of each other. The critical
competition for them occurs with the older trees in the form of
light interception (most important) from above and nutrient inter-
ception from below. Since the lifting of the light inhibition is
very slow in terms of potential seedling growth, the plasticity of
seedlings becomes a factor. Being so adaptable, one can fit itself
to any rift by lateral growth; occasionally one with over go per cent
of its leaves on a far side branch will be found. Maximum spatial
crowding is reached in the sapling age, and consequently the most
critical competition of the life cycle occurs here.

_ Approaching the climax of elimination, the first to go are those
with too few leaves in the light. Among other causes this may be
due to shortness, distortion, slow growth, or accentuated crowding.
There are more weaklings and distorted trees at this age than at
any other, and in their removal comes the critical stage in spacing
evolution; for removal of the very old trees above results in intensi-
fied slinaation and more rapid destruction, since the spacing
interval is increased 20-100 times before the third life age is reached.
In general, the sapling race is not only a struggle for life by vertical
elongation, but it is one in which the time element is crucial.

Having reached the third age, the tree is nearly immune from
lateral competition, the permanent stand being formed here.
Future struggles are against rot, parasites, wind, and weather, both
root and branch systems now being amply competent to maintain
life processes. Since the tree’s juniors must be limited to what it

40 BOTANICAL GAZETTE [JANUARY

cannot use, survival remains with the soundest and best developed.
The final picking off in ages 3 to 5 seems slight. In the last age the
result of unequal battle with parasites comes out and all fall in turn.
It is the rare exception that remains to the last age, one of 100,000
seedlings that have lived and died within its present sphere of influ-
ence (GrEaAson). In the last age beech is largely replaced ‘by
maple in most localities, so that a pure maple-hemlock stand is
found in places.

Seasonal periodicity is shown, for example, in the synfolium,
_ present only during summer and part of spring and fall. Each fall
it joins the preceding synfolia in the dead leaf layer, thus proving
how little actual solid was in it. Chromatic periodicity is more
accentuated than in Illinois. The synfolium is yellowish green in
spring, quickly turning to the darker green retained through the
summer. In fall the birches turn yellow and many maples scarlet.
Growth periodicity is shown in the alternating periods of relatively
slow growth and active elongation (especially of saplings), according
as the inhibition of an older generation persists or is removed.

Evidences of dying or death are unobtrusive but ever present.
Nature seems very wasteful in her development of adult trees.
The number of saplings pinned down by débris is remarkable.
Many are thus actively destroyed instead of passively dying for
lack of light. It is needless death and destruction that should in
large measure be eliminated by scientific forestry, thus obviating
the waste of space and light taken to develop useless plants at the
expense of those later useful. Below the sapling synfolium is a
death layer which bears, aside from the trunks present, many dead
and dying branches.

Branches do damage in proportion to their size, the culmination
of destruction coming in the fall of an adult tree. Tree or branch
fall is primarily caused by basal rotting. Wind, rain, or lightning is
usually required to crack the last resistant marginal alburnum of a
branch or unbalance the tree (which has a different type of balance
from a branch, so that it can break through proportionally much
more wood). The big tree rarely catches on others to remain
propped for a while. It usually falls without warning, snatching
off branches from its neighbors, and pinning down or lacerating

1920] CLAY BERG—UPLAND SOCIETIES 41

hundreds of young trees and saplings. There is thus left a natural
glade to be closed by regenerative succession.

Competition and parasitism are the main causes of death.
Destruction of branches at the synfolium base by lack of light is
due partly to slower growth, but primarily to disadvantageous
position. In old trees the most serious causes of death are boring
insects, fungus rot, loss of foliage and branches, and (possibly)
decreased vascular efficiency.

The parasites present are mainly insects and fungi. Neither
show prominently in the forest, remaining more or less hidden
except for fungus sporophores and many adult insects. Forest
floor pileate forms are characteristically present, but individually
not very abundant. Coons (20) points out that fungi may also
be grouped in formations, certain species being characteristic of
each type of habitat. Conditions in the climax forest, especially of
the lower levels, favor fungus growth by the relative twilight, more
equable temperature, and higher humidity prevailing.

Tunneling bark beetles are present, and, because Tilia ameri-
cana L. and Fraxinus nigra Marsh. seem more often attacked, the
insects may aid in keeping maple and beech dominant. These
beetles, being cambium eaters, would seem more destructive than
the duramen eaters, such as Tremex columba of maple and beech.

Leaf parasites (23) seem rather few. Rhytisma acerinum forms
black blotches on maple and oak leaves. A similar fungus causes
scarlet patches. Mites causing bag formation on the upper
surface of maple leaves, and plant lice occur persistently; woolly
aphids (Schizoneura) blight the alder, but rarely injure the hard-
woods; several sorts of leaf-eating Microlepidoptera are found that
are worst on the birches, while the tent caterpillars (Clisiocampa)
confine their attention almost exclusively to rosaceous trees. Thus
the maple and beech would seem to enjoy relative immunity from
the more serious pests, which may aid in their retaining dominance.
The débris includes leaves, twigs, branches, trunks, and stumps,
most being found on the ground. Arrest is rare for very light
objects (leaves and twigs) and for heavy large ones (trees), but for
different reasons. The numbers of the different sorts of débris vary
inversely with their size. The leaf layer at the ground surface,

42 BOTANICAL GAZETTE [JANUARY

furnishing protection and humus, is characteristic of the climax
forest. Unlike conifer needles, the leaves fuse during the winter
into a single tough layer averaging 2-5 mm. thick, thinnest in late
summer and thickest in late fall. Its base continually decomposes,
adding to the humus below.

Twigs are always abundant on the forest floor; and since the
herbage i is open they interfere little with it. Their fall is light and
they reach the ground soon, being smooth and slender and not
liable to catch. They are easily pushed aside by all plants.
Branches often remain on the tree for some time after death, but
combined action of basal rotting and weather eventually tears them
loose. Yet even then one may not fall, at times hanging by a strand
of cortex and alburnum that is often remarkably small, or it may
catch on the parent or a nearby tree at one of the crotches or lower
branches. Usually one large branch is found on every 3-10 sq. m.
Annual vegetation can be hurt for but one season, but perennial
aerial parts are injured permanently.

The fallen trunk rots slowly, leaving a soil ridge and a narrow
lane for many years. Stumps rot as slowly into a low mound, but
hemlocks remain standing as giant stubs 10-20 m. tall with the
branches lost. Their wood rots until it cuts like putty, but the
bark will hold up for many years, being thick and tough, rich in
tannin, and not rotted by fungi or eaten by insects. Maples and
beeches rarely leave such stubs, except as the result of fungus en-
trance some distance up the trunk. Those that are left do not
stand long.

Lichens are found sparingly on trunks above the sapling syn-
folium and on exposed trees. They are also seen on the larger
branches and are more common on the maples and hemlocks,
because the beech affords poor foothold. A year after a big tree
falls, however, its bark is covered by a luxuriant and varied growth |
of foliose lichens, in consonance with the removal of the substratum
from a xerophytic to a richly mesophytic environment.

Mosses are not common on vertical trunks. Ferns are not seen
_ as epiphytes in this region, though not from lack of either individuals
or species. Both may be found growing on rotting stubs (not
hemlock).

1920] CLAYBERG—UPLAND SOCIETIES 43

FLORISTICS

Gates (7) and Coons (20) define many of the societies found in
the region discussed here. It is hoped in a later paper to point
out the differences observed from the floristic types recorded and
described by these authors (1, 19). __

NorMAL TyPE.—This occupied practically all the uplands of
the region before clearing. There are 70-90 per cent sugar maple,
5-30 per cent beech, and the hemlock is a constant tree also, running
as high as 25 per cent in some localities. Since many of the forests
are not strictly undisturbed and hemlock is taken first (for barking),
a low percentage or absence of it may be thus explained in some
instances. Other trees occur in varying but small proportions,
among the more prominent being Tilia americana L., Fraxinus nigra
Marsh, Acer spicatum Lam., A. pennsylvanicum L., Ostrya virginiana
Koch, Betula alba L. var. papyrifera Spach, Prunus pennsyloanica
L. f., P. virginiana L., Betula lutea Michx. f., Acer rubrum L., Ulmus
fulva Michx., U. americana L., and Staphylea trifolia L.

As type of this forest a quadrat in the primary undisturbed

‘forest back of Bay View was taken (500 sq. m. in 20 squares).
There were 17 big trees here, averaging 47 cm. diameter, making
the average area occupied 29 sq. m.; 8 of these being maple, 5 beech,
and 4 hemlock, although the tictilock is more numerous than in
much of the nearby woods. Below these trees was a fairly open
stand of saplings, those over a meter in height numbering 649; of
which 57.3 per cent were sugar maple, 30.1 per cent Acer spicatum,
6 per cent beech, the other trees present being Acer pennsylvanicum,
A. rubrum, Ulmus fulva, and Fraxinus nigra. Their average diame-
ter was found to be 1.41 cm.; the average number per square
(25 sq. m.) was 32.5. In a square studied near Walloon Lake
the number of saplings was 89 and the average diameter 1.9 cm.
The larger size and number in the latter square were probably
because it had no adult trees in or very near it, while the Bay View
quadrat had, so that its saplings had received only part of the =.
and nutrients that would otherwise be available.

It will be noticed that Acer pennsylvanicum and A. spicatum are
prominent at age 2 in the first quadrat, and also in some of the
climax forest. This is a similar phenomenon, but more accentuated

44 BOTANICAL GAZETTE [JANUARY

than the one observed by Cooper (4) in regard to the balsam on
Isle Royale. These two maples are ecologically of the sapling type;
that is, they reach their highest development in a form ecologically
equal to the second life age of the sugar maple. Beyond maturity
they have such a high death rate that, although often as abundant
as sugar maple at the sapling age, they are rarely represented in
the third age. GLEASON’s (11) significant tabulation shows Acer
pennsylvanicum as the dominant tree after clearing. The con-
trary occurrence from that of the maple is observed in the case of
the hemlock, very few seedlings of which are seen in the climax
forest, although a fair number of the adults are constantly present;
for, because of scattered occurrence of young trees, it is not probable
that the species is dying out.

Shrubs are not common through the climax forest. Cornus
alternifolia L. f. is often seen in the Bay View woods. The char-
acteristic shrubs of the region include Sambucus racemosa L.,
Ribes Cynosbati L. (transitions to R. gracile Michx. seem to occur),
R. lacustre Poir. (along Little Traverse Bay), Lonicera (L. hir-
suta Eaton is occasional along Little Traverse Bay), Taxus cana-
densis Marsh, Rubus Idaeus L., R. allegheniensis Porter, and Aralia
racemosa L. The last is really an herb, but it is so tall and large
that it is ecologically a shrub and occupies the shrub stratum.

The herbage of the climax forest is varied and fairly abundant.
The prevernal flora is sun-loving and close, forming continuous
masses of foliage composed of few species and many individuals.
In the upland woods the dominant species is Dicentra canadensis
Walp., but in the woods along Little Traverse Bay Dentaria diphylla
Michx. appears more prominent. ‘Transition forms to the summer
flora occur; for example, Caulophyllum thalictroides Mithx. is
prevernal in leafing and flowering, while in fruit it is strictly aestival.
Allium tricoccum Ait. also has prevernal leaves which die down
before the scape appears in early summer.

The summer herbage is more scattered and richer in species, its
richness varying with the age of the youngest tree generation. It
is shade tolerant, and characterized by about 50 species. Particu-
larly characteristic among them are Botrychium virginianum Sw.,
Aspidium spinulosum Sw., Trillium grandiflorum Salisb., Maianthe-

1920] CLAYBERG—UPLAND SOCIETIES 45

mum canadense Desf., Tiarella cordifolia L., Geranium Bicknelli
Britton, Mitchella repens L., and Aralia nudicaulis L. <A typical
(x sq. m.) quadrat at Walloon Lake contained Geranium 10, Viola
canadensis 10, Allium 9, Osmorhiza Claytoni 2, Galium triflorum 1,
Dentaria 2, grass 2, Botrychium t.

At Bay View the herbs and shrubs show something of a tendency
to segregation into patches dominated by different types. Three
quadrats of a square meter each taken here were: (1) Tiarella 92,
Streptopus roseus 8, Dentaria 4; (2) Taxus 24, Dentaria 8; (3)
Allium 116. |

VARIANTS.—Both xerarch and hydrarch types can be distin-
guished. The xerarch occurs on high or hilly ground and is both
drier and more open. Either hemlock or beech is prominent. The
hydrarch type, shown well behind Bay View, is found in valleys and
low ground, either occurring along streams or bearing standing
water part of the year. The characteristic trees are linden and
yellow birch. The herbage is closed and rich, as mdny as 40 species
being found. Marchantia, Equisetum scirpoides Michx., orchids -
such as Listera contallarioides Torr., Impatiens biflora Walt., Viola
canadensis L., Glyceria nervata Trin., Polygala paucifolia Willd.,
Habenaria spp., and Lycopus spp. are common; but the most
typical character is the large number of ferns. Among the more
Prominent are Adiantum pedatum L., Asplenium angustifolium
Michx., A. acrostichoides Sw., A. Filix-femina Bernh., Phegopteris
Dryopteris Fee, P. polypodioides Fee, and Aspidium spinulosum Sw.

NATURAL CLEARINGS.—Natural glades and openings occur
throughout the primary forest. The fall of a tree is followed in a
month or so by a rank herbage growth (11), not the fireweed-
composite type often following lumbering, but largely composed of
naturally native forest path and clearing species. Among these,
by the second or third year, spring up suckers and seedlings of
maple and beech, mixed with certain clearing tree species, which
shade out much of the herbage growth in four to six years. In the
healing of the forest gap the clearing trees may be prominent at
first, but they are gradually replaced by the maple and beech in
Course of time. Among the clearing trees are Prunus pennsylvanica
L., P. virginiana L., Tilia americana L., Ostrya virginiana Koch,

46 BOTANICAL GAZETTE [JANUARY

Ulmus fulva Michx., Fraxinus nigra Marsh., and Betula alba L.
var. papyrifera Spach. The herbage is of such species as Araha
racemosa L., A. nudicaulis L., Dactylis glomerata L., Panicum spp.,
Ranunculus abortivus L., Solidago caesia L., S. canadensis L.,
Osmorhiza Claytoni Clarke, and Geranium Bicknelli Britton.
Rubus idaeus L. often plays a large part if the clearing is not too
small and the seeds are introduced at a time when room is available.

Secondary scrub and interference
TERMINOLOGY SUGGESTED (3, pp. 145~166)
. Revegetation
a) Primary: original or primary vegetation of the area.
b) Secondary: vegetation coming up after removal of primary society.
(1) Repetitive: secondary succession following course of primary.
(2) Nonrepetitive: not following primary.

La |

dS
z
o
©
oo
my
lol
=}
co
sk
oO

d) Destructive: all vegetation removed; includes areas where refuse is
red off.
. Recurrence of interference

a) Simple: occurs once; area left alone thereafter.

b) Repeated: interim for partial recovery allowed.

c) Continuous: repeated at short intervals so that no recovery is allowed.
. Terrain: left clean, dirty (refuse left), or burned
Successional phases

a) Regressive: reversion to an earlier stage, or Becotoit floristic type.
b) Delayed: same Foe but individuals of an earlier
c) Static: approximately same stage and life age.

Progressive: succession hastened.

Ecological state
a) Stage: as used for some point in succession of species.
b) Age: as used for some point in succession of individuals.

wo

i

XERARCH TREELESS SOCIETIES
The upland herb and shrub floras appear to show five secondary
societies.
FIREWEED SOCIETY.—Most of its species are not native. In
clearings, particularly those resulting from destructive interference,
with dirty or burned terrain, strongly regressive changes occur,

1920] CLAYBERG—UPLAND SOCIETIES 47

especially where the soil is stirred up or the humus destroyed. It
has been said (3, 9, 10) that this new association is not ‘‘lower”’
than a forest, since it is new, but regression can be conceived as
meaning return to a stage where less use is made of the space and
light available. Furthermore, forest will finally replace such a
society, just as it blots out any naturally formed clearing. The
change here is toward a physically and physiographically youthful
aspect (rejuvenation of CowLEs, 6). The surface soil gives the
prevailing tone to the society, being gray or yellow, powdery, and
nearly free of available water, radiating intense heat on a warm day.

Into this xerophytic habitat comes a clearing flora showing but a
limited number of species, among which Epilobium angustifolium L.
is dominant. Other species of importance are Sisymbrium altissi-
mum L., Erigeron canadensis L., Cirsium arvense Scop., and Ver-
bascum Thapsus L. Besides these occur also Sisymbrium canescens
Nutt., Lactuca scariola L., L. canadensis L., L. spicata Hitch.,
Ambrosia artemisiifolia L., Gnaphalium polycephalum Michx.,
Erechtites hieracifolia Raf., Sonchus asper Hill., S. arvensis L.,
Erigeron annuus Pers., and E. ramosus BSP.

Most of these species have a profusion of wind-borne seeds, and
they take possession by having seeds there, by resistance to harsh
conditions, by rapid growth, and by seeding profusely over the area
when once started, thus getting ahead of competitors. They are
finally shaded out by saplings. Certain species of Lactuca were
observed 3-4 m. tall, and while in “young” dry areas a society as
Scattered as in a desert may be found, in full development this
flora can form a positively impenetrable jungle, particularly on
hilly ground with a dirty terrain. Few societies in this region can
show such a wide variation of form corresponding with as wide a
range of environmental conditions.

THORN sOcIETY.—Its species are natives of the region. This
society occurs much in natural clearings, but because artificial
clearings and cutovers are so much more numerous in this region
at present, the thorn flora is found mostly in such places. It is
dominated first by Rubus idaeus L., which is commonly succeeded
in turn by R. allegheniensis Porter. The latter can hold a patch for

yeats against saplings when pickers are numerous enough to

48 BOTANICAL GAZETTE [JANUARY

keep the trees down; but if the patch be undisturbed, the sapling
growth can replace blackberry in a few years (pin cherry in 3 or 4
years). The thorn species are widely sown by animals that eat
the fruits, so their armament serves rather for climbing and indivi-
dual protection than for keeping out animals. Erigeron canadensis
L. is the commonest holdover from the fireweed flora. Forerunner
saplings are also very usually present. Thus this stage serves as
transition where herb and tree meet. It can hold a vicinity far
longer than the fireweed society.

FERN SOCIETY.—Pleris aquilina L. occurs with some grass on
xerarch areas. Because of its flat-topped habit and proneness to
form a pure stand of fronds of equal age and height, this fern forms a
synfolium at from 40-80 cm. from the ground, the distance varying
with age. Bracken is commonly associated with grass sod, coming
in after continuous destructive interference in the drier hilly upland
and exposed shore hills. Aspen often is found with it, both entering
particularly after fire (12). Mvyrica asplenifolia societies of farther
south (Little Manistee to Brethren) appear to be equivalent.

MILKWEED socrETty.—The species is not native of the region.
Asclepias syriaca L., while common as a weed, and found in all sorts
of societies, also feria a persistent, ubiquitous, and actively invad-
ing society of its.own on drier upland and lowland areas. Like
Pieris, it is often associated with grass turf, possibly because of the
natural openness of the two societies. It probably enters after
more severe and continuous interference than the bracken can
endure. Because of its underground rhizome, xerophytic structure,
tremendous reproduction, and efficient seed dispersal, it can main-
tain itself after continued cutting and even plowing. It probably
would precede sumac in reclamation of unused upland pastures,
and is prominent where interference (and turf?) prevents later
successional stages in pasture and grassy upland.

Sumac socrety.—These species are probably native here. Rhus
typhina L. and R. glabra L. occur in upland pastures, along roads,
and in clearings, being primarily a bordering association (thus later
than milkweed), occurring more often on closed (and especially clay)
soil. It forms a stand 1-2 m. high, much opener than the milkweed,
and being taller permits more herbage. Along roads it is often

1920] CLAY BERG—UPLAND SOCIETIES 49

followed by maple-beech, although the regenerating climax forest
can enter at any stage of the upland secondary series. One of the
evidences suggesting equivalency of the thorn, fern, and milkweed
societies is that sumac can follow any one, and that any of the three
can succeed the fireweed flora.

XERARCH TREE SOCIETY

The aspen—white birch=pin cherry society varies much in general
form and specific content, so three types (consocies) are found.
The dominant trees are Populus tremuloides Michx., P. grandi-
_- dentata Michx., Betula alba papyrifera, and Prunus pennsylvanica L.

PIN CHERRY-—BIRCH.—The birch may be absent. Pure pin cherry
stands in particular occur in upland and middle level clearings fol-
lowing the thorn society. They can spring up suddenly. In spite
of good light the lower branches remain slender and die early.
The mode of growth is the arboreal expression of the clearing
society type; all are also soft wooded. The pin cherry is eco-
logically peculiar in being strongly excurrent, with elongate form
and filiform type of branches, wasting the minimum of tissue on
laterals and trunk diameter. This gives it great power of vertical
elongation, an aid in competition for place in clearings, but makes it
short-lived; so in time it must give way to longer-lived hardwoods.
Thus the forest of this type is fairly open, with good herbage.

ASPEN-PIN CHERRY.—This is a dry open xerarch type found
along shore, especially on the ridge back of the Nipissing cliff.
Often half the trees will be dead and the remainder equally divided
between the two species. Herbage is scant or none, and dead
twigs and branches are thick below. Sucha stand is far opener than
either maple-beech or cedar forest, although similar to the cedar
in number of dead trees.

ASPEN-PTERIS.—This is found more on dry levels inland. The
small-toothed aspen dominates (90 per cent or more); the large-
toothed aspen is prominent; and some birch may be found. Being
secondary, the herbage below the bracken synfolium suggests a
high type of primary forest. The following species are found:
Gaultheria procumbens L., Cornus canadensis L., Lonicera hirsuta
Eat., Corallorhiza spp., and Lycopodium tristachyum Pursh. The

5° BOTANICAL GAZETTE [JANUARY

bracken seems to interfere little with this herbage, in fact may
protect it. They occupy a different level and seem comple-
mentary (22).

The preceding types are alternative. Which enters depends
on soil conditions, topography, and seeds present. Aspen succeeds
best after fire and in higher dry ground. Pin cherry seeds are
bird-scattered (and fertile longer), thus being more apt to reach a
favorable place. The xerarch tree society is able to enter in many
cases where climax forest is sufficiently cleared, either with or with-
out intervention of treeless stages. The greater the degree and the
quicker the recurrence of interference, the more likely regressive
changes are to occur, its amount and the environment determining
whether the ensuing secondary state be repetitive or non-repetitive,
and, if the latter, whether it be thrown back to tree, shrub, or herb
stage (the farthest being the fireweed semi-desert), that is, the
degree of rejuvenation.

Regeneration of the climax forest may be speedy, hardwood
saplings following a mixture of fireweed and thorn. This results in
a remarkable floristic mixture. Behind Bay View a nearly pure
stand of red maple has been formed after cut over. At Walloon
Lake the beech is apt to dominate in the regenerating climax forest.
In other places Acer spicatum and A. pennsylvanicum are impor-
tant. Ifthe xerarch tree society takes charge of a district it may be
followed by yellow birch and elm (18) before the climax supervenes.
Grass turf may prevent tree entrance (11, 12), but it would appear
that milkweed and sumac, at least for dry upland, could replace it.

Discussion

The upland societies here studied show that most of the area
of this character was occupied before settlement by climax forest.
The forest itself (as any climax) is static in species but dynamic
as to individuals, so that the climax is not final but recurrent.
Five life ages may be singled out in this forest, each with its own
dimensions and ecological characters. Thus the sapling age shows
maximum increase in size for given decrease in number per unit
area, so that competition between trees of equal age is keenest
here.

1920] CLAYBERG—UPLAND SOCIETIES 51

For the foliage layer is coined the name synfolium, and its devel-
opment and ecological significance are analyzed. In connection
with mortality, it is pointed out that very many saplings are pinned
down oe débris, and thus actively wneisen instead of passively
dyin

The study of Kent County, Michigan, by LivincsTon (18) shows
five societies, while the writer has distinguished four here. While
this might be interpreted as meaning Kent County was not so far
advanced, it must be remembered that: (1) oak and hickory play
more important réles in succession in the Grand Rapids area than
at the north end of the southern peninsula; (2) LivincsTon recog-
nizes three societies containing oak, and two with maple; in this
region the four primary types tend to be mutually exclusive;
(3) LivincsTon uses herbs as well as trees in definition of his socie-
ties, which the author has not felt justified in doing for this region
as yet.

In examining the distribution of the secondary societies, it
seems probable that the hypothesis laid down by Livincston
holds in large measure, but it may be that this is only for societies
enduring rather small differences in moisture retaining power of the ~
soil; for the fireweed society (secondary) is able to endure a wide
range in this particular, being shaded out, but not dried or drowned
out.

Throughout this region the response of the plant societies to
interference and changed environment has been adaptive, in so far
as their constitution allowed. Some natural societies, such as the
blackberry, are fitted to survive in partly wild areas. Others can
invade the fields in competition with the crops. Characters
required are quick entry, speed of vertical growth, quickness of
fruiting after germination, quantity of seed production, and effi-
ciency of distribution; for a given society may be here today and
gone tomorrow, plowed under.

The best example of the weed type among the societies previ-
ously discussed is the fireweed society, which contains species that
are being rigidly selected by man in his fight against them. These
plants are likely to survive long after the maple-beech society is
banished to the wood lot and city parkway; for evolution is toward

52 BOTANICAL GAZETTE [JANUARY

the herbaceous annual type (as pointed out by Srynotrr and
BAILEY in past evolution also), as best suited to the mobile environ-
ment furnished.

The author desires to extend his thanks to Professor HENRY C.
Cow Les, of the University of Chicago, whose help and encourage-
ment have made the completion of this work possible. He also
wishes to thank Mr. Cuartes W. FAttass, of Petoskey, and Pro-
fessor CHARLES H. Swirt, of the University of Chicago, for their
cooperation during the progress of the work.

Oax Park, ILL.

LITERATURE CITED

1. BEAL, Ww. J., Observations on succession of forests in northern Michigan.
Rep. Mich. Forest. Comm. 1:25-29. 1888
- Brown, F. B. H., Forest associations of Wayne County. 10th Rep.
Mich. Acad. Sci. 209-217. 1917.
3- CLEMENTS, F. E., Plant succession. Publ. 242, Carnegie Inst. Wash. 1916.
4- Cooper, W. S., Climax forest of Isle Royale, Lake Superior, and its
development. Bor. GAZ. 55:1-44, 115-140, 189-235. 1913.
OWLES, Henry C., Ecological setatibie of the vegetation on the sand dunes
of Lake Michigan. Bor. Gaz. 27:95-117, 167-202, 281-308, 361-391.
1899.

N

3

as

—_—_—, ee i oe of Chicago and vicinity. Bor. Gaz.

31!73-108, 145-182.

Gates, F. C., Veins of the region in the vicinity of Douglas Lake,

Cheboygan Couey: Michigan. 14th Rep. Mich. Acad. Sci. 46-106. 1912.

‘ elation between evaporation and plant succession. Amer. Jour.
Bot. 4: ‘ieagh. IQI7
9. GLEASON, H. A., Vegetation of the inland sand deposits of Illinois. Bull-
Ill. State Lab. Nat. Hist. 9:23-174. 1910.
, The plant association. Bull. Torr. Bot. Club 44:463-481. 1917.

, Development of two plant associations in northern Michigan.
Plant World 21:151-158. 1018.

12. GLEASON, H. A., and McFartanp, F. T., Introduced vegetation in the
vicinity of Douglas Lake, Michigan. Bull. Torr. Bot. Club 41:511-521.
1914.

13. Harper, R. M., Car window notes on vegetation of the Upper Peninsula
of Michigan. 13th Rep. Mich. Acad. Sci. 193-198. 1913.

14. ———, Superficial study of pine barren vegetation of Mississippi. Bull.

Torr. Bot. Club 41:551-567. 1914..

oy

1920] CLAY BERG—UPLAND SOCIETIES 53

15.

)
a

HARSHBERGER, J. W., Ecologic ma of flora of mountainous North
Carolina. Bor. Gaz. 36:368-383.

903.
. LEVERETT, FRANK, Outline of the brit of the Great Lakes. 12th Rep.

Mich. Acad. Sci. 19-42. 1910.

. LEVERETT, F., and Taytor, F. B., Pleistocene of Indiana and Michigan.

Monograph 53. U.S. Geol. Surv. 1-529. 1915

. Livincston, B. E., Distribution of upland plant societies of Kent County,

Michigan. Bor. Cie. 35:36-55.

3+
- Moore, B., Reproduction in coniferous forests of northern New England.

Bor. Ge: 64:149-148.

IQI7
- RutHven, A. G., e¢ al., Biblogical survey of sand dune region on the south

shore of Sadan Bay, Michigan. Mich. Geol. and Biol. Surv. Pub. 4
Biol. Ser. 2. ro1r.

Scuimper, A. F. Plant geography on a physiological basis. Rev. .
transl. Oxford. 190

SHERFF, E. E., Venice of Skokie Marsh. Bull. Ill. State Lab. Nat.
Hist. 9:575-610. 1910.

- SORAUVER, Pau, Handbuch der Pflanzenkrankheiten. Berlin. 1913.
. TRANSEAU, E. N., Bog plant societies of Northern North America: their

geographic distribution and ecological relations. Bor. Gaz. 36:401-420.
1903.

Wuttrorp, H. N., Genetic development of the forests of northern Michigan.
Bor. Gaz. 31: 289-325. 1gor.

Yapp, R. H. . Stratification i in the vegetation of a marsh, and its relation to
evaporation laa temperature. Ann. Botany 23:275-319. 1909.

FIELD AND LABORATORY STUDIES OF VERBENA
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 257
M. KANDA
(WITH PLATES VI-IX AND TWENTY-SIX FIGURES)
Introduction

In Gray’s New Manual of Botany (edition of 1908), 8 species
of Verbena are described as occurring in the Eastern United States.
These are classified into two sections, of which the first is further
subdivided into three groups. Five of the 8 species grow wild in
the vicinity of -Chicago, namely, Verbena urticaefolia L. and
V. bracteosa Michx., belonging to the first and third groups respec-
tively, and V. angustifolia Michx., V. hastata L., and V. stricta
Vent. to the second group. These three last named species occur
abundantly at Stony Island, a southern suburb of Chicago, where
the conditions of prairie, damp, and dry ground are met with
successively as one proceeds from the north to the south end of
the locality. Here the three forms grow in their characteristic
ecological situations: V. stricta on the prairie, V.. hastata in damp
low places, and V. angustifolia on high dry ground. On examining
the Verbena plants, one is rather surprised to find that there are
many intermediate forms which can scarcely be assigned to any
of the three species with certainty. The question arises, therefore,
as to whether they are hybrids or mutants of the three species.

The present work was undertaken to determine whether or not
there are any cytological differences in the fertilization phenomena
and early stages of development between these forms. The results
were rather negative as regards the genetic nature of the intermedi-
ate forms; that is, with slight exceptions, no significant differences
were found between them. Many of the observations upon the
embryonic development, however, are sufficiently interesting to
merit description. These will therefore constitute the chief subject
matter of the present paper, such facts and suggestions as I am able
to present regarding the origin and nature of the intermediate forms
being added at the close.

Botanical Gazette, vol. 69] (54

1920] KANDA—VERBENA 55

This work was carried on at the Hull Botanical Laboratory,
University of Chicago, under Professor CHARLES J. CHAMBERLAIN,
to whom I wish to express my sincere thanks for suggesting the
problem, and my appreciation of his kind advice throughout the
progress of the work. My acknowledgments are also due to
Professor JoHn M. Coutrer for his kindness in placing the con-
veniences of the laboratory at my disposal.

Taxonomic observations ‘

Although one can easily recognize the specific characters of the
original species, V. angustifolia, V. stricta, and V.. hastata, it is
impossible to arrange the forms intermediate between them in.a
linear series with regard to all of their contrasting characters. In
other words, all of the characters do not vary in the same direc-
tion, so that if one distributes them among the original species
with reference to one character, a
different distribution would be re- |
quired for some other character.
Examples of the 3 species and the 2
6 intermediate forms which I was
able to collect are given in figs. 1-9
(pl. VI). Figs. 1} 3, and 7 are V. 9
angustifolia, V. stricta, and V. 8
hastata respectively, and the others
are the intermediates arranged be-. 3 4 5 6 7
tween the 3 species in accordance , :
with théir degree of similarity to eet = cit oh aca
them, as nearly as this could be between, originals and intermediates.
determined. I have attempted to
represent diagrammatically the morphological relationship between
the originals and the intermediates by the triangle shown in text
fig. 10; the numbers on the triangle refer to the figures in plate VI.
The three apices (1, 3, 7) indicate the three original species, and
the points along the sides of the triangle show the probable posi-
tion of the intermediate forms with reference to them. For ex-
ample, 4 is believed to be nearer to 3 than to 7, and 5 is probably
about midway between 3 and 7. The contrasting characters of
all of the forms are given in detail in table I.

[JANUARY

BOTANICAL GAZETTE

56

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1920] KANDA—VERBENA 57

It is necessary to consider whether or not the differences between
these plants might not have been induced through adaptation and
response to the local conditions in which each type may happen to
be growing. Such an influence of local factors can be recognized
at Stony Island in different degrees; thus, for instance, while the
color of the flowers of V. hastata varies greatly with individuals,
without reference to the conditions of the habitat, the shape and
texture of the leaves of this species are plainly responsive to the
surroundings, those plants growing in dry places having narrower
and stiffer leaves than those inhabiting wet situations.

I believe I have eliminated this possibility in selecting my
materials, and those which I regard as intermediate forms are not
cases of modifications due to individual differences or adaptation
to local conditions. Thus I have found forms 1 and 2 growing
under the same external conditions at one location; forms 4, 5, and 6
growing together at another place; and forms 8 and 9 growing at a
third spot.

Cytological observations
MATERIAL AND METHODS

The spikes of V. angustifolia (fig. 1), V. stricta (fig. 3), and
V. hastata (fig. 7), and the form intermediate between stricta and
hastata (fig. 5) were collected during July and August 1918 at
Stony Island. The apical part of the spikes, the pistils, and the
young fruits in different stages of development were fixed in chrom-
acetic acid and corrosive sublimate-acetic acid solutions, the former
giving the best results. In the case of the pistils and fruits, it was
found advantageous to pick off carefully or partially remove the
calyx tubes, as they interfered with the rapid penetration of the
fixing fluid. Sections of the apical part of the spikes were cut
5, 10, and 15 w in thickness; pistils and young plants, 5 and 7.5 un.
Flemming’s triple stain and iron alum haematoxylin were used, the
former giving quite satisfactory results.

All of the four forms mentioned were examined in more or less
complete series. V. angustifolia is chosen as a type for the purposes
of description, but most of the statements are applicable to the
others also, and they will be mentioned specifically only where
differences between them make a separate discussion necessary.

58 BOTANICAL GAZETTE [JANUARY

DEVELOPMENT OF FLOWER

The first evidence of the formation of flowers is the appearance
of papillae in the axils of the bracts (fig. 11a); these papillae are
the primordia of the receptacles of the flowers. The outline of
the receptacle soon becomes angular through the upward growth
of four hemispherical protuberances from its distal surface (fig. 11),
and soon afterward its base produces a ring-shaped outgrowth
(fig. t1c). The former develop into the stamens, and the ring
immediately afterward separates into the corolla and the calyx

Fics, 11-17.—Floral development in V. angustifolia; X35

tube (fig. 12). The appearance of the carpels is indicated bya
broadening of the receptacle (figs. 12, 13).

In fig. 13 the calyx tube has begun to curve inward over the
top of the flower. Within this the corolla tube, the hemispherical
young stamens and the two carpels appear in succession. Their
later stages are shown in figs. 14-17.

DEVELOPMENT OF MEGASPORE AND EMBRYO SAC

When the ovule has reached the stage shown in fig. 15, the sub-
epidermal megaspore mother cell that terminates the axial row
of the nucellus can readily be distinguished from the surrounding
cells through its larger size and large nucleus (fig. 18). The

1920] KANDA—VERBENA 59

megaspore mother cell and its nucleus with a prominent nucleolus
continue to increase in size (fig. 19)... Two divisions then occur
which result in the typical formation of a row of four megaspores
(figs. 20, 21); this takes place when the ovule is about at the stage
represented in fig. 16. The innermost of the four megaspores is
the largest, and is destined to develop into the embryo sac (fig. 22).

Successive stages in the development of this basal megaspore,
accompanied by the destruction of the other three megaspores, are
shown in figs. 22-25. The nucellus, consisting of a single layer of
cells, surrounds the row of megaspores
(fig. 21). It eventually becomes so dis-
tended by the enormous expansion of the
developing embryo sac that it ruptures, and
the ruptured nucellus is then carried down-
ward as a cap on the growing embryo sac,
as was previously described by MotTTIER
(14) in Arisaema, CALDWELL (1) in Lemna,
and MERRELL (13) in Silphium. In the
next stage (fig. 26) the embryo sac lies free
in the space between the funiculus and the
integument, and the yellowish-brown rem-
nants of the nucellus are observable cap-
ping the micropylar end of the sac.

The phenomena of the enlargement of
the sac, the division of its nuclei, and the
destruction of the cells of the nucellus do
not occur simultaneously, but these pro-
cesses take place at different rates. The
development of the megaspore and the
fate of the nucellus are exactly the same
as described by MERRELL for Silphium.

When the embryo sac reaches maturity (fig. 26), taken from
an ovary in the stage represented in fig. 27, the sac is several times
larger than it was when inclosed in the nucellus, very slender in
shape, and always constricted just above the egg apparatus. The
egg apparatus seems to be typical. The nucleus of the egg is
several times larger than the nuclei of the synergids and contains

Fic. 27.—V. angustifolia:
mature pistil with mature
embryo sac; X35.

60 BOTANICAL GAZETTE [JANUARY

in the resting condition a fine chromatin network and a large, often
vesicular, nucleolus. After,the fusion of the polar nuclei, which
occurs near the middle of the sac (fig. 25), the resulting endosperm
nucleus approaches the egg apparatus. At this time, as shown in
fig. 26, the endosperm nucleus still possesses two nucleoli, evidences
of its binucleate origin, and is considerably larger than the egg
nucleus. It is frequently in contact with the egg. There are
three very small but typical antipodal cells.

The nutritive jacket surrounding the embryo sac of Verbena
usually consists of a single layer of cells derived from the inner
epidermal layer of the integument, and it develops especially at
the micropylar end, investing the egg apparatus of the embryo sac.
The cells of the jacket have conspicuous brownish contents, among
which are numerous starch grains. Rather frequently a portion
or portions of the jacket cells inclosing one or more grains of starch
protrude into the embryo sac.

DEVELOPMENT OF MICROSPORES

At the stage shown in fig. 14 the hypodermal archesporial row
is distinguishable, and the succeeding stages follow the usual course
of development (figs. 28, 29). There may be only a single longi-
tudinal row of spore mother cells, but one or two longitudinal
divisions of the primary sporogenous row may take place (fig. 30).

The pollen mother cells within a loculus do not divide quite
simultaneously, so that several different stages of the reduction
division may be found among them (figs. 31-33). It is rather
difficult to count the number of chromosomes in this species
(V. angustifolia) because they are remarkably small and slender,
but it was ascertained that 8 is the 2x number. In the second
maturation division the two spindles usually lie across each other
as in fig. 33.

In V. angustifolia there are two different types of tetrad
formation. In the one case the peripheral cytoplasm of the pollen
mother cell is left over to form a wall for the tetrad, this wall
subsequently disintegrating (figs. 34, 35), while in the other case
the entire mother cell is utilized in the formation of the tetrad
(fig. 36). Figs. 37-41 give successive stages in the development of

1920] KANDA—VERBENA 61

the pollen grains. The wall of each microspore gradually thickens
and sometimes 4 great many starch grains may be observed in the
interior (fig. 39). Cases of accumulation of starch grains in the
pollen have been reported by Murseck (15), IsHtKAwa (11),
and others. In Oenothera IsHIKAWA states that ‘‘the plasm con-
taining starch grains in the pollen tube is poured into the attacked
synergid,”’ but in this case no starch is present in the pollen tube
(fig. 42). A large vacuole appears in the pollen grain for a time
(fig. 40), but it soon fades away and the first vegetative cell is cut
off (fig. 41). More advanced stages could not be observed, as the
contents and wall of the pollen grains become extremely dark in
color. While these changes are occurring, the tapetum and middle
layer disintegrate.

FERTILIZATION

It is very difficult to obtain clear pictures of the stages in which
the male nuclei are on the point of fusing with the egg cell and
the endosperm nucleus. In the first place the egg apparatus is
rendered very indistinct through the presence of deeply staining
cytoplasmic substances around it. I believe this deeply staining
material is the result of a concentration of the cytoplasm and the
inclusion within it of nutritive substances destined for the endo-
sperm. The abundance especially of starch grains around the
€gg apparatus greatly confuses its appearance with the gentian
violet stain. Secondly, the synergids seem to be more ephemeral
in Verbena than in other plants, and soon become converted into a
tenacious mucus-like material. This material from the dis-
organized synergids also stains very deeply. Thirdly, when the
pollen tube enters the egg apparatus, a part of the disorganized
nucellar cap penetrates into it with the tube and always gives rise
to a figure of peculiar shape and staining properties (figs. 42~44,
46). MERRELL states that in Silphium “the pollen tube passes
along the outside of the cap which usually crowns the embryo sac
and enters the sac just beyond its free margin.” In Verbena,
however, the pollen tube, entering the sac at the micropylar end,
thrusts itself through the nucellar cap (fig. 42), just as in Lemna,
described by CALDWELL.

62 BOTANICAL GAZETTE [JANUARY

Figs. 43 and 44 show stages of fusion of the male and female
nuclei. In fig. 43 one of the male nuclei is in contact with the egg
and the other with the embryo sac nucleus, and in fig. 44 one of
the male nuclei has fused with the egg nucleus.

In connection with the fertilization process it should be reported
that at this time a proteid-like substance makes its appearance in
the cavity between the carpels and ovules (figs. 26, 27). This
material forms a network, probably as the result of coagulation
by the fixing agent, and stains deeply with cytoplasmic dyes. The
only suggestion which can be offered as to the function of this sub-
stance is that it may be related to the nutrition of the pollen tube,
since it appears just before fertilization and disappears shortly
after that process is completed.

FORMATION OF ENDOSPERM

After fertilization the primary endosperm nucleus moves toward
the center of the embryo sac, and its first division takes place there.
This division is followed by the formation. of a wall which divides
the sac into two approximately equal chambers, the micropylar
and the antipodal chambers (figs. 45, 46). Such a formation of a
two-chambered embryo sac has been observed in many plants,
both monocotyledons and dicotyledons, by HormerstTEer (10),
SCHAFFNER (17), CAMPBELL (2), GuIGNARD (6), Hatt (8), Mur-
BECK (15), Cook (3), and others. Several other cases are mentioned
by Courter and CHAMBERLAIN (4).

The nucleus of the micropylar chamber gradually changes its
position, moving toward the middle of the chamber, and soon after-
ward produces a great many free nuclei (figs. 46, 47), around
which walls are subsequently formed, beginning at the micropylar
end. This mode of development of the endosperm corresponds to
the third type in HecetMater’s (9) classification. Twelve chromo-
somes, that is, the 3x number, were often counted in these nuclear
divisions. The nucleus of the antipodal chamber also moves toward
the center of that chamber, and increases in size, but does not
undergo division for a long time (figs. 46, 47). The antipodal cham-
ber elongates like a haustorial tube, extending to the chalazal
extremity of the ovule, sometimes becoming exceedingly curved.

1920] KANDA—VERBENA 63

Figs. 48 and 49 illustrate two parts of the same embryo sac; the
endosperm tissue is seen to be fully formed in the micropylar
chamber, while the antipodal chamber is still uninucleate.

A large amount of starch is present in the embryo sac, as was also
observed by GuUIGNARD (7) (Cesirum), D’HuBErRtT (5) (Cactaceae),:
Wess (18) (Astilbe), and Lioyp (12) (Galicium). This is ob-
servable not only a little before fertilization, but more especially
after fertilization has occurred (figs. 43, 44, 46). Fig. 46 shows
starch not only in the micropylar and antipodal chambers, but also
even in the egg cell. It is evident that the starch grains in the
micropylar chamber are always larger than those in the antipodal
chamber. These starch grains are naturally closely related to
those in the nutritive jacket. I have already mentioned that
jacket cells loaded with starch grains may protrude into the sac.
Sometimes one gains the impression that the starch grains have
entered the sac through the destruction of the thin walls of the
jacket cells. Such a direct transfer of starch, however, is hardly
to be credited, partly because there are many fewer grains in the
sac than in the jacket, but mainly because the walls of the jacket
cells seem to be composed of very resistant material, since they
persist for a long time apparently intact. In the V. hastata
material I found occasionally an entire absence of starch grains
in the jacket cells, and in such cases the development of the embryo
sac is always remarkably retarded, and the egg apparatus is absent
(fig. 50).

The further development of the endosperm is the same as in
Sagittaria, described by SCHAFFNER (17). While the micropylar
chamber is becoming filled with walled endosperm tissue through
free nuclear division, the enlarged nucleus of the antipodal chamber
still remains undivided. Sometimes it divides once or twice
(fig. 51), forming two or three free nuclei which enlarge enormously.
Meantime the endosperm tissue continues to develop, finally
extending from the micropylar chamber into the antipodal chamber,
forcing the large cell which occupies the antipodal chamber up
to the antipodal end} At about this time the antipodal cells
disintegrate (fig. 52). The large cell at the antipodal end of the
chamber gradually diminishes in size, and finally disappears.

64 BOTANICAL GAZETTE [JANUARY

In CouLTER and CHAMBERLAIN’S book (4) it is stated that
“the endosperm is said to develop only in the antipodal chamber
* in Loranthus, Vacciniaceae, Verbenaceae, etc.’’ This statement
should be corrected as far as it concerns the various species of
Verbena which I have studied.

DEVELOPMENT OF EMBRYO

The proembryo divides in two by a transverse wall and remains
without further change for a long time (fig. 49). It then elongates,
with accompanying divisions, reaching a condition like that
illustrated in fig. 53, where it is a
filament of varying length, con-
sisting of several cells. The apical
cell of the filament then divides
longitudinally (fig. 54), followed by
another longitudinal and a trans-

Fics. 54-57.—V. hastata: succes- Verse division in either order, result-
sive stages of development of embryo; jng in an octant stage (figs. gé. 56).
pg he mire haa ooo natal The dermatogen, periblem, and

plerome layers are next differ-
entiated in the sahiyo (fig. 57), which now occupies the end of a
long suspensor. The appearance is identical with that of Capsella.

Relationship of intermediate forms

Cook, comparing two species of Sagittaria, S. variabilis and
S. lancifolia, says: ‘“‘With such striking external differences one
would naturally expect equally interesting internal differences,
but to my surprise I found the development of the embryo sac
and embryo of S. lancifolia practically the same as had been
described by ScHaFFNER for S. variabilis.”’ Twas equally surprised
on comparing the forms of Verbena. I selected as the intermediate
form for comparison with the original species the type designated
in the earlier part of this paper as no. 5 (see fig. 5), because it is
one of the most abundant of the intermediates and because it
seemed to be halfway between V. stricta and V. hastata. In the
following account the morphological and cytological characters
of this intermediate are compared with those of the three species.

1920] KANDA—VERBENA 65

The flowering period of V. angustifolia comes earlier than that
of V. stricta, V. hastata, and the intermediate form between them,
so that the last three flower at the same time. For this reason one
would expect that intermediate forms between V. angustifolia
and the other two species would be rather rare, while those between
V. stricta and V. hastata would be more common, if these inter-
mediate forms are really hybrids. As a matter of fact, the relative
abundance of the intermediates corresponded to the expectation.

The young ovule of V. hastata at the stage in which the mega-

‘spore mother cell first makes its appearance (fig. 15) is rounded
(fig. 58), while that of the other three forms is somewhat flattened,
as indicated in fig. 59. The young ovule of the intermediate form
is therefore similar to that of V. stricta.

58 2
Fics. 58, 59.—Diagrammatic outline of young ovule: fig. 58, V. hastata; fig. 59,
other 3 forms.

_ The size of the mature embryo sac varies considerably within
each species owing to individual variations, but an approximate
comparison of its size at the same stage in the four forms can be
made without difficulty. The following table gives the average
length of 12 embryo sacs of the four forms at three different stages.

TABLE I
Intermediate form
Name : V. angustifolia V. stricta between V. stricta V. hastata
and V. hastata
xs
Fig. 26 il o.260 mm. o.225 mm. 0.185 mm. 0.185 mm.
Fig. 51 stage..... ©. 500 0.460 0.390 0.310
Fig. ag a stage) 0.460 0.540 0.360 °.340

The breadth. of the sac in all cases is about 0.02-0.03 mm. The
figures show that with regard to the length of the embryo sac the
intermediate form resembles V. hastata more than it does V. stricta.

66 BOTANICAL GAZETTE [JANUARY

At the time of the first mitosis of the microspore mother cell
the flower buds of the 4 forms are in different stages of development.
As shown in figs. 60-63, the buds of V. angustifolia and V. hastata
are in a relatively young stage when this event occurs, those of
V. stricta in a much later stage, and the intermediate form at a
stage between these two. In respect to this character, then, the
latter occupies an intermediate position.

As described in a preceding section, tetrad formation occurs in
V. angustifolia in two different ways, with or without persistence
of a rim of cytoplasm from the mother cell. In V. séricta the:
cytoplasm always persists in this manner, forming, even at the
first mitosis of the microspore mother cell, a deeply stained border

Fics. 60-63.—Comparison of florets at time of first mitosis in pollen mother cells:
fig. 60, V. angustifolia; fig. 61, V. stricta; fig. 62, intermediate form between V. stricta
and V. hastata; fig. 63, V. histeter 3 5.

around the central portion where the mitosis is occurring (figs. 64,
65). In V. hastata no such cytoplasmic border is ever formed
around the microspores, but all of the cytoplasm of the mother
cell is utilized in the production of the pollen grains. The inter-
mediate form is like V. hastata in this regard (figs. 66-68).

V. angustifolia has 8 chromosomes as the 2x number. A late
prophase and metaphase of the first reduction division in this
species are shown in profile view in figs. 69 and 70. The other 3
forms have 12 chromosomes as the 2x number. A metaphase of
V. stricta and an early anaphase of the intermediate form from the
_ side and end are illustrated in figs. 71-74. Iregret that in V. hastata
I was unable to find just the same stage to compare with these, as
all of my material of this species is either a little too early or too

1920] KANDA—VERBENA 67

late. It is safe to conclude, however, that 12 is also the 2x number
for this species, since in the early telophase of the first division
(fig. 75) 6 chromosomes are clearly present at each pole of the
spindle. I have further often counted 12 chromosomes in all of
the forms except V. angustifolia in the anaphase stage in young
locular cells of anthers, and 18 chromosomes, the 3x number, in
the endosperm cells. The behavior of the chromosomes of the
intermediate form in mitosis is entirely normal, and like that of the
original species. No such abnormalities as were described by
ROSENBERG (16) in Drosera hybrids can be recognized.

Owing therefore to the unfortunate fact, which could not be
foreseen, that both of the original species selected for comparison
with a form intermediate between them have the same number of

Fics. 69-75.—Mitosis of pollen mother cell: figs. 69, 70, V. angustifolia; figs. 71,
72, V. stricta; figs. 73, 74, intermediate form between V. stricta and V. hastata; fig. 75,
V. hastata; 1500,

chromosomes, cytological observations upon them do not serve
to settle the question as to whether the intermediate form is a
hybrid or not. It is clear that the intermediate form does not
differ cytologically from the original forms, and that its mitotic
behavior is entirely normal. These facts, if they have any sig-
nificance at all, tend to suggest that the intermediate is not a hybrid,
but rather a mutant of one or the other of the original species.
This could be determined only by breeding it through several
generations and observing whether its characters are fixed or not.

Cytological studies of the forms intermediate between
V. angustifolia and the other two species might have yielded more
definite results, because it differs from them in the number of its
chromosomes. Unfortunately I did not collect any material from
these forms, as they are relatively rare.

68 BOTANICAL GAZETTE [JANUARY

Summary

Several intermediate forms were found between three species
of Verbena which grow on Stony Island, V. angustifolia Michx.,
V. stricta Vent., and V. hastata L., which can be arranged taxonomi-
cally between the three species in question. Embryological and
cytological studies were made on the three species and on one of
the forms intermediate between V. hastata and V. stricta in order
to determine the genetic nature of the intermediate.

From the cytological point of view, nucellar cap, nutritive
jacket, and chambered embryo sac are pointed out as the char-
acteristic features of these forms. The reduced number of chromo-
somes is 4 in V. angustifolia and 6 in the other three.

It was not possible to decide from the cytological studies whether
the intermediate form is a hybrid or not, since both of the original
species from which it might be supposed to have sprung were
found to have the same number of chromosomes. The chromo-
some behavior of the intermediate was like that of the two species
and entirely normal. Some of its developmental characters are
intermediate and some are similar to either V. stricta or V. hastata.

NorMAL CoLlLecE

HirosHma, JAPAN

LITERATURE CITED

1. CALDWELL, O. W., On the life history of Lemna minor. Bor. Gaz. 2737-66.
figs. 59. 1899.

2. CAMPBELL, D. H., A morphological study of Naias and Zannichellia.
Proc. Calif. Acad. Sci. 1:1-62. pls. 1-5. 1897

3. Coox, M. T., The embryology of Sagittaria lancifolia L. Ohio Nat.
7:97-101. pl. 8. 1907

4. Coulter, J. M., and CuamBertatn, C. J., Morphology of angiosperms.

5. D’Husert, E., Recherches sur le sac embryonnaire des plants grasses.
Ann. Sci. Nat. Bot. 2:37-128. pls. 1-3. figs. 66. 1806.

. GUIGNARD, M. L., Recherches sur le sac embryonnaire des Phanérogames
Angiospermes. Ann. Sci. Nat. Bot. 13:136-199. pls. 3-7. 1882.

, La double fécondation chez les Solanées. Jour. Bot. 16:145-167-
Sigs. 45. 1902.

8. Hatt, J. G., An epee study of Limnecharis emarginata. Bot.
Gaz. 33:214-219. pl. 9. 190

a

7.

1920] KANDA—VERBENA 69

9. HEGELMAIER, F., Untersuchungen iiber die Morphologie des Dikotyledonen-
Endosperms. Nova Acta Leopoldina 49:1-104. pls. 5. 1885; rev. Bot.
Centralbl. 25:302-304. 1886.

10. HOFMEISTER, W., Neuere Beobachtungen iiber Embryobildung der Phane-
rogamen. Fahid, Wiss. Bot. 1:82-188. pls. 7-10. 1858.

11. IsHtwaka, M., Studies on me embryo sac and fertilization in Oenothera.
Ann. Botany 32:297-317. 7. figs. 14. 1918,

12. Lutoyp, F. E., The eee pds of the Rubiaceae. Mem.
Torr. Bot. Club 8:27-112. pls. 8-15. 1

13- MERRELL, W. D., A contribution to oe life history of Silphium. Bor.
GAZ. 29:99-133. bis 3-I0. 1900.

14. Mortirr, D. M., On the development of the embryo sac of Arisaema
triphyllum. Ror. GAZ. 17:258-260. pl. 18. 1892.

15- Murseck, S., Uber die Embryologie von Bette rostellata Koch. Handl.
Svensk. Vetensk. sae 36:21. pls. 3. 190

16. ROSENBERG, O., Cytologische und orb bagacie Studien an Drosera-

oe yesGuaa. Handl. Svensk. Vetensk. Akad. 43:1-65. pis. 4

Sigs. 33. 1909.

SCHAFFNER, J. H., Contribution to the life history of Sagittaria variabilis.

Bor. Gaz. 23:252-273. pls. 20-26. 18

- Wess, J. E., A morphological study of the flower and embryo of Spiraea.

Bor. Gaz. 33:451-460. figs. 28. 1902.

*
~JI
7

al
oo

EXPLANATION OF PLATES VI-IXx

Figs. 10-17, 27, 54-63, 69-75 are in the text; all the others in the plates.
All drawings were made with an Abbé camera lucida at table level. Figs. 11-
17, 27,and 60-63 were drawn with Zeiss compensating ocular no. 4 and Spencer
16 mm. objective; figs. 18-25, 28-41, and 64-68 with Reichert ocular no. 18
and Spencer 4mm. objective; figs. 26 and 42-53 with Zeiss compensating
ocular no. 4 and Bausch and Lomb 1/12 oil immersion objective; figs. 69-75
with Reichert ocular no. 18 and Bausch and Lomb 1/12 oil immersion objec-
tive. Text figures reduced one-half, plates nearly two-thirds in reproduction.
The original magnification will be specified for each figure in the plates.
; PLATE VI

All figures reduced five-twelfths.

Fic. 1.— Verbena angustifolia Michx.

Fro, 2 amempgeniead intermediate form between V. angustifolia
Michx. and V. stricta Ven

Fic. 3.—V. stricta Sei

Fics. 4-6. —Paxonomically intermediate forms between V. stricta Vent.
and V. hastata L.

rg ie —V. hastata L.

Fics. 8, 9.—Taxonomically intermediate forms between y. hastata L. and
V. esata Michx.

70 : BOTANICAL GAZETTE [JANUARY

PLATE Vil

Fics. 18-25 magnified 700 diameters; fig. 26 magnified 800 diameters;
figs. 22 and 25 are V. hastata; all the others V. angustifolia. :
Fic. 18.—Details of ovule outlined in fig. 15, showing megaspore mother

Fic. 19.—Nucellus of older ovule.
Fics. 20, 21.—Megaspore mother cell nucleus dividing into two (20),
and four (21

Fic. 22 so ncekhs of fertile megaspore and its encroachment on sterile
cells; nucellus cells somewhat stretched.

Fic. 23.—Embryo sac with 2 nuclei.

Fic. 24.—Embryo sac with 4 nuclei, reconstructed from 4 sections.

Fic. 25.—Embryo sac with polar nuclei in contact.

Fic. 26.—Details of a part of ovary outlined a avis fig. 27, 8 showin
mature embryo sac invested by jacket; proteid-lil b
ovule and carpel.

PLATE VIII

Fics. 28-41 magnified 700 diameters; figs. 42-45 magnified 800 diameters;
figs. 42, 45 are V. stricta; all the others V. angustifolia.

Fic. 28.—Longitudinal section of young anther showing sporogenous cell
row and surrounding layers.

Fics. 29, 30.—Transverse and longitudinal — . an older
anther, showing granular and mostly binucleate tapetal : fig. 29, cells of

iddle layer, also arene fig. 30, some rows of ee ee cells, with

nuclei in synapsis

Fic. 31 —Three os mother celle in first division; tapetal cells with
2 nuclei.

Fic. 32.—Two pollen mother cells in anaphase of first division.

Fic. 33.—Early telophase of second division in pollen mother cell.

Fics. 34, 35.—Tetrad formation; some cytoplasm of mother cell concerned
in wall formation.

Fic. 36.—Tetrad formation; cytoplasm of mother cell not concerned in
wall formation.

Fics. 37-41.—Successive stages of development of pollen grain: fig. 39,

pollen with starch grains; fig. 40, pollen with large vacuole; fig. 41, pollen

with vegetative and generative nuclei.

Fic. 42.—Pollen tube just thrusting itself through nucellar cap.

Fics. 43, 44.—Fertilization: fig. 43, male nuclei fusing with egg and endo-
sperm nucleus; pollen tube and starch grains shown.

Fic. 45. Kirt division of primary endosperm nucleus followed by wall
formation.

BOTANICAL GAZETTE, LXIX PLATE VI

KANDA on VERBENA

PLATE VII

BOTANICAL GAZETTE, LXIX

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ar

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em yh ed sO we ae

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Toe = MINKE aa

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29
KANDA on VERBENA

PLATE VIII

BOTANICAL GAZETTE, LXIX

KANDA on VERBENA

PLATE 1X

BOTANICAL GAZETTE, LXIX

ror
OX

eter ee ; * ‘a . 4 ee _
SE sD, RT 2 ; 4 Kehoe
“OA oe a ‘iM ere, i a

in Sepa Th snag OEMS ee S ‘

KANDA on VERBENA

1920] KANDA—VERBENA 71

PLATE IX

Fics. 46-53 magnified 800 diameters; figs. 64-68 magnified 700 diameters;
figs. 50, 68 are V. hastata; figs. 64,65, V. stricta; figs. 66,67, intermediate form
between V. stricta and V. hastata; all others are V. angustifolia.

Fic. 46.—Embryo sac separated into micropylar and antipodal chambers:
nucleus in micropylar chamber just in mitosis; reconstructed from 4 sections.

Fic. 47.—Embryo sac in which endosperm tissue is developing from
micropylar end; single large undivided nucleus with 2 nucleoli in antipodal
ssrictag

Fics. 48, 49.—Two portions of one embryo sac: fig. = antipodal chamber
still cae Zt 49, micropylar chamber filled with tiss

1G. 50.—Embryo sac retarded in development by hii of starch in
jacket; only 3 nuclei in center.

Fic. 51.—Mitosis of endosperm nucleus in antipodal chamber.

Fics. 52, 53.—Two parts of more advanced embryo sac: fig. 52, antipodal
part with one large resting cell; fig. 53, micropylar part with filamentous
embryo.

Fics. 64, 65.—Pollen mother cell in reduction division: fig. 64, metaphase
of first division; fig. 65, early telophase of second division.

Fics. 66, 67.—Pollen mother cells: fig. 66, metaphase and telophase of
first division; fig> 67, telophase of second division.

Fic. 68.—Pollen mother cell in telophase of second division.

A CHEMICAL ANALYSIS OF SUDAN GRASS SEED
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 258
F. M. SCHERTZ
(WITH ONE FIGURE)

The method as here outlined was originally taken from the
methods of WALDEMAR Kocu,' who employed it in the analysis of
brain tissues. The method was then further modified by F. C.
Kocu,? of the department of physiological chemistry, University
of Chicago, where the work was chiefly on animal tissues. The
method was again modified to meet the needs of plant tissues.

Outline of method

Dry or Soraens seeds

| L
Soluble sae (F,+F:) Insoluble residue (F;)
| |

Ether soluble portion (F;) Water, alcohol soluble portion (F.)

Fraction 1 (F,) is the ether soluble portion; fraction 2 (F:)
is the portion soluble in alcohol or water; and fraction 3 (F;) is
the portion which is insoluble in ether, water, or alcohol. The
dry seeds were ground finely before making the extraction, while
the germinating seeds were ground in a mortar as finely as possible.
The material was then placed in the extraction cups and extracted
for 4 hours. A 1-hour extraction with ether was then made and
the ether extract was added to the alcohol extract. The residue
was dried, ground in a mortar, and then a water extraction was
made. This water extraction and the residue was then made up to
70 per cent alcohol and again extracted with 95 per cent alcohol for
12hours. Insome cases this extraction was found to be insufficient,

*Kocu, WaLpeMar, Methods for the quantitative chemical analysis of animal
tissues. Archives Neurology and Psychiatry 4:11. 1909; also Jour. Amer. Chem.
‘Soc. 314: 1329-1364. 1909.

* Outline for the analysis of tissues as prepared by F. C. Kocu.

Botanical Gazette, vol. 69] , [72
t

1920] SCHERTZ—SUDAN GRASS SEED 73

and consequently the extraction was prolonged for another 12 hours
ormore. The extraction was conducted at the boiling point of the
solvent, using the Kocu extractor.

F, and F,.—All of the alcohol, water, and ether extracts were
added to each other, and then the whole was rapidly evaporated
down to a thick syrup on the water bath. It was then transferred
to a vacuum desiccator and dried until nearly a constant weight was
obtained. This took from one to three weeks. The air in the
desiccator was changed once or twice daily. This gave the weight
of F, and F,. The dry mixture of F, and F, was now extracted with
anhydrous ether; this extract was F,, and the residue was F,. The
evaporating dish plus F, was dried and again weighed, giving the
weight of F, by difference, and also the weight of F,. The ether
extract F, was divided into two portions, one portion being used for
the determination of sulphur and phosphorus, and the other for
nitrogen. The residue was dissolved or suspended in 70 per cent
alcohol and made up to a volume of rooocc. Of this, 50 cc. was
used to determine the total sugars; 100 cc. for ash and for solids;
200 cc. for nitrogen; 100 cc. for free reducing sugars; and 550 cc.
for sulphur and phosphorus.

3---F, was then dried at 1o5° C. in an electric oven to nearly a
constant weight. The whole was then pulverized thoroughly
and fractions of it, ranging from 0.5 to 2.0 gm., were used for the
determination of sulphur, phosphorus, nitrogen, total carbohy-
drates, ash, and crude fiber.

Moisture was obtained by difference. Nitrogen was estimated
by means of the Kjeldahl method as modified by Gunning and
Armold. The nitrogen was multiplied by 6.25 to give the protein.
Sulphur was estimated by the fusion (Na,CO;+KNO,) method,
precipitated, and weighed as BaSO,. ‘The filtrate from the sulphur
determination was used and the phosphorus was determined from
it by the Neumann-Pemberton method, by titration. Organic
matter was determined by taking the weights of the ash F, and F,
from the dry weights of F, and F; respectively. Sugars were
estimated by the Bertrand volumetric method in connection with
the Munson and Walker tables. Total reducing sugars were
found by adding 10 cc. of HCl (sp. gr. 1.125). for every 100 cc.

74 BOTANICAL GAZETTE [JANUARY

of water used with the sample, and then boiling on a reflux con-
denser for 2.5 hours. They were then estimated as glucose.’
Crude fiber was determined after the method in Bulletin no: 107,
Bureau of Chemistry. 1912.

Analysis of unhulled dry seeds

The air dry weight of the seeds used in each case was 25 gm.
The seed analyzed was that of Sudan grass (Holcus halepensis
sudanensis [Piper] Hitchcock or Andropogon halepensis sudanensis
Piper). In each case two analyses were made and the results,
together with the average of these two, are given in table I. The
hulled seed was 70.62 per cent of the whole seed by weight, hence
the hulls were 29.38 per cent of the whole seed by weight.

Analysis of seeds after germination

An analysis was made of the unhulled seeds which were kept in
the refrigerator for 16 days at a temperature ranging from 8 to 20° C.
A small percentage of the seeds showed signs of sprouting. In each
case 25 gm. of seed were used.

This study was undertaken with the hope of discovering some
of the early changes which take place on germination, and also
because Sudan grass has promise as a forage grass. In comparing
the unhulled dry seeds with the unhulled germinated seeds, it was
found that the weight of F, remained constant, F, lost 2 per cent,
and F; lost 3 per cent on germination. ‘The protein in F, decreased,
while that of F, increased somewhat. The total protein content of
the germinated seeds increased about 1 per cent, due to the building
of protein from the reserve substances. No change of importance
was noted regarding the sulphur or phosphorus content. The
ash of F, increased slightly at the expense of the ash of F;. The
amount of organic matter in F, decreased 1.5 per cent, while that
of F; decreased 3 per cent; or a total loss of organic matter of about
5 per cent due to respiration. The greatest changes were found in
the sugars. The total reducing sugar of F, decreased 2 per cent,
free reducing sugar decreased slightly, and the total carbohydrates
decreased about 9 per cent. The decrease in sugar-like products

3 MATHEWS, ALBERT P., Physiological chemistry. 2d ed. New York. 1916.

SCHERTZ—SUDAN GRASS SEED

1920] 75
TABLE I
I II Average
DAGISEUNG 215 oe a ert ae ees Sate Ce Sil Se ES 14.05 13.95
NRT OR Biss ons eee 0's od Va be oe es beh ices 3.60 3.69
F Be a BU aa vind of ol Cece 0a ok ie 9-54 9.54
OT et ee ee 72.92 72.92 72.82
TORE Sick V eas oar EST ese eS 100.00 100.00
Protein*
Bescon errs yee 0.02 0.02
Ee. ct Slap co cle ee eee eee 1.23 1.23
1 PR SIE SOUTER Seay a Ge eee 5.44 4.96 5.20
Total beso etre od ancl ahs wees 6.20 6.45
Sulphur
Bee a ee a ree eee 0.02 0.02
ee ee or Goa iaic Oe sac Sa ee ee ek ae 0.05 0.05
Fy teas va ee oe 0.07 oO. 0.08
Wptal oes oc bs reece eae ik was creeks 0.16 0.15
Phosphorus
ee ee eT Pere Peer g: Cee eet eee 0.004 0.004
F, $e aed 2b © wih Wie 0a a la lg ew ae Gk eed ww cade ome eee aad 0.06 0.06
Feces is Bs eee ak °.20 0.24 0.22
OCA (Gry rede ets cee eee es hee 0.304 0. 284
Ash (inorganic matter)
Meee ey tak Pee ie ee he aee e 0.65 0.65
F, Se ee re ae ee ee ee ee 4.61 4.56 4.58
ROHAN 6 Oe Sic reenact ean ade es oes | 5<a% | 5-23
Organic matter
LPO gee Ne aoe eee BRO aA STG ge 8.80 8.89
By ie a es ey oe 68.31 68.16 68.24
TOM oi ce Rae | 77.08 | 297-93
Sugars
Fe total reducing cigs dose epee ee reek , 2.39 2.39
Bu S000 POCUGE 6. 5g os cas ee pele kes eee ts 0.96 0.96
F, carbohydrates... ....,....:. 58.59 62.36 60.47
ROU Gai bs oi Meee ee CES 64.75 62.86
Crude fiber
Finca f 5.12 4-77 4-95
* The tal 4 1 a 1¢, I + nt 7 7.23 and 7.38 per dank

76 BOTANICAL GAZETTE [JANUARY

TABLE II
RESULTS OF ANALYSIS OF HULLED DRY SEEDS*
I II iit Average
pe ae eee oe 12.53 Re ce eas 12.76 12.46
Weight of 4, pera Gate ene yay © Etter ck Gee ac earn 4.72 4.48
Se is eo 6.56 Beas mt es ae 7.87 7.243
a F Ren Og ota 76.67 76.19 74.65 75.84
Total aoe yas TOO OO ee oe te 100.00 100.00
Proteins
et is es oo Saar ee, oe 0.01 0.01
| PEE SITS ge ree ey (ee eee 1.07 1.06
Fes Virals Wawra 7.28 7.26 7.54 7.30
fi SEC EMER penne RSW geenrata Ane Sel ae 8.62 8.43
Sulphur
LE OO Ni ante ok Oe he. 0.01 0.01
| LINE a ae ye Meee Corre eure epee 0.08 0.06
F; ie Fg eit Selah Weedeater cg 27 0.21 0.17 Oi: 22
2 ee Os 0. 26 0.29
Phosphorus
Be cee bee ie Crete eam sk ee 0.002 0.002
Wisc cy rade cece sees O00 fokca 253. ke 0.10 0.09
F, ge Wb Sw wa we aie Gon a 0.26 0.22 0.25 0.24
SOE. nots in os bee acc ee LN ee 0.352 0.332
Ash
RS A Re eos er OSs hic 0.82 0.82
F, a iecaies w wibwnw bie aes 1.41 26 1.26 1.34
| Ee eaenenre. 2.23 | cme ee | 2.08 2.16
Organic matter
tae Oe Spey eee 5.74 De pe Rae ci .05 6.40
F; 1 ere oye 6 ene eB eee 6 75.26 74.83 73.39 74.59
fi ey Sera | 81.00 | ga NC Nee | 80.44 80.90
Sugars
F, total reducing. ..... OBR ee ee 0.34
F, free reducing....... O99 > die Gs 0.26 0.27
F; carbohydrates... ... 67.29 64.72 66.48 66.16
fc) Bee eee OF.O8 gy en dpen ie a ie 66.50
Crude fiber
Pee Se ee 1.08 eo hee: Ute aera 1.03
* Air dry a oe i a vs was 25 gm.

1920] SCHERTZ—SUDAN GRASS SEED 97
TABLE III
I II Average
Moisture absorbed 6s cs 48.22 45.72 46.07
OMEUTG oi i's ks eee Se 18.34 19.12 18.73
WS OE Fis Sas ies en 3-25 3.94 3.60
te ee hea) aes 8.03 7.58 7.80
ere Bye Pee ee 70.38 69.36 69.87
UR eek eee 100.00 100.00 100.00
Proteins
WihcGy eek S 6 Es eee ee ee 0.01 0.01 0.01
ORNS capapes Dele ee 2.20 2.66 2.43
RD Rl i se Berge a 5.10 4.93 5.02
WOM ees ee a a 7 ai 7.60 7.46
Sulphur
WES a ais oo es wid eee a ees es 0.01 0.01
Pe a 0.05 0.05 0.05
| AIR ey tye gar ae 0.16 0.13 0.15
ROU Sj acu s ver eeey Fs OVE eee yn sees 0.19 0.21
Phosphorus
We een des cok ee 0.002 0.001 0.001
PS cee nn fee SS 0.06 0.08 0.07
We ee 0.21 0.23 0.22
BS ae Peedi ewer 0.272 0.311 0.291
Ash
is gies ete os ik a vos Gace x GBS teak aide rons: 0.85
We epee ge 4-54 4.49 4.52
ROO bs Oks SOG ei tac eevee 5.36
Organic matter
Sy ee Pig 7.19
WEG sg es kee 65.84 64.87 65.36
WOR cae ss 7 ay CONE SR aR Ser 72.55
Sugars
Pe al teens Se ee 0.49 ©.49
Be free reducing. oy ks 5 0.40 0.33 0.37
F; carbohydrates............. 48.84 53-24 51.04
POM iio Oo ee i he iS 53-73 51.53
Crude fiber
PW ie oon vin oi ie ah 5.54 5.08

78 BOTANICAL GAZETTE [JANUARY

was about 11.5 per cent, due to respiration. Crude fiber remained
practically constant.

When the hulled dry seeds were compared with the unhulled
dry seeds, it was found that the weight of F, was 1 per cent greater

in the former, and it was 2 per cent greater in the latter for F.,

while F; of the former was about 3 per cent greater. The proteins of
TABLE IV
UNHULLED DRY SEEDS
Material I II Average
Free reducing sugars.......... I.10 0.93 1.02
Sucrose-like sugars............ 1.04 2.43 2,19
Total reducing sugars......... 3.32 2.9% 3.02
Total cailohyarate Bye: 60.00 59.60 59.80
SOU coo a 63.32 62.31 62.82*
Unhulled seed grown at room temperature
Free reducing sugars.......... 1.02 ©.96 0.99
Sucrose-like sugars............ 1.46 1.30 1.47
Total reducing sugars......... 3.24 3-25 3.24
Total carbohydrate F;......... 43-36 45.88 44.62
TOT os eae 46.60 49.13 47.86
Unhulled seed grown in refrigerator
Free reducing sugars.......... 0.89 0.75 0.82
Sucrose-like sugars............ 1.64 ¥.34 1.49
Total reducing sugars ......... 2.69 2.69 2.60
Total carbohydrates F;........ 43-51 43-93 43.72
WWE hs eee a 46.20 46.62 46.41
* Ten gm. of seed were hydrolyzed for 2.5 hours and gave a total carbohydrate of 65.30 per cen t

F, and F, were about the same, but the protein of F, of the hulled
dry seeds was more than 2 per cent greater. The ash of F, was
slightly more in the hulled dry seeds, while the ash of F, was over
3 per cent greater in the unhulled seeds; hence a greater part of the
ash was in the hulls. The organic matter of F, of the unhulled dry
seeds was 2.5 per cent greater, while in F,; it was 6 per cent less.
The free reducing sugars were slightly greater in the unhulled seeds,

1920] SCHERTZ—SUDAN GRASS SEED 79

the total reducing sugars were 2 per cent greater, while the carbo-
hydrates were over 6 per cent less. Five times as much crude fiber
was found in the unhulled seeds.

A further analysis of the sugars was then made. Two samples
of 25 gm. each of the dry seed were analyzed for sugars alone. Two
samples of 25 gm. each were grown at room temperature (16-24° C.)
for 3 days, and two other samples were grown in the refrigerator
for 32 days. The seeds in each case were extracted as indicated
into the two portions F, and F;._ F, was then evaporated down and
made up to a volume of 500 cc., of which 100 cc. was used for the
determination of total reducing sugars; three 50 cc. samples for
the inversion of cane sugar by weak hydrolysis at 67—69° C. for
10 minutes; and the remainder was used for free reducing sugars.
All of the F; was hydrolyzed for 2.5 hours by adding 300 cc. water
and 30 cc. hydrochloric acid (sp. gr. 1.125). From small portions
of this the total sugars of F, were determined.

From table IV it is seen that when the seeds germinate the
sucrose-like sugars decreased about 1 per cent, while there was a
decrease in the total carbohydrates of about 15 per cent.

TABLE V
SUDAN GRASS COMPARED WITH OTHER SEEDS
. -f

Seeds Water | Protein) Fat | N-free) Crude) ach | sugar

Triticum sativum 13.37 | 10.93 | 1.65 | 70.01 | 2.12] 1.92] 27

Hordeum sativum 12.95 | 10.01 | 1.87 | 67.88} 4.23 | 3.06] 6-7

Secale cereale 3,37 | 12.30 1.68 | 69,36 2.16 2.24 a~3
Mays: 2 ecu; 13.32 Q-I0 | 4-5 68-69 [1.6-2.7| 1.60 |1.5-3.7
Sorghum aggre ie 14.58 9 44 | 3-18 | 68.55 2.54 SE tees y;

Oryza sati u 13.17 13 | 4.974 78.40 1. 1.03 | 1-2
a {anhailed - 2.00 ec ae Se
Avena sativa ie oe § | 10.461" &: 27 68 9.07 | 3.02 a

6.44 |..3. 75-74°| 4.95 | §.24 | 2.390
is sudanensis {hulled sate 2.47 1° 8.43 4.4.48 | 70.487) 1.03} 2.10 | 3.4aT
Unhulled germinated oa by * pir aaEN 18.72 7.46 | 3.60 | 59.78*] 5.08 5.36 | 2.69T
Sudan grass seed (Kansas 47 | 13-69 | 3.81 | 63.6, ae ye ae aie

* too — (protein +ether extract +-ash-+moisture+crude fiber).

t Total reducing sugars as. dex
+ THompson, G. E., Sudan grass fe Kansas, Kansas Agric. Exper. Sta. Bull. 212. 1916.

It is of interest to compare these results with those of some other
workers. KJELDAHL, working on barley seed, found about 4.7 per
cent cane sugar in the green malt and 1.1 per cent in the ungermi-
nated barley. O’SuLLIVAN found in ungerminated barley 0.8-1.6

80 BOTANICAL GAZETTE [JANUARY

and in malt 2.8-6.0 per cent cane sugar. These results on Sudan
grass gave in each case less than 1.0 per cent of cane sugar, figuring
the reducing sugar as cane sugar.

Compared with other grasses‘ it is very similar to Sorghum
avenaceum, which gave the following results: ash 5.63, protein
3.29, cellulose 36.7, and fat 1.67 percent. Of the ash, 1.5-3.0 per
cent was CaO, P.O;, MgO, and SQ,.

Catalase activity
In each case 0.2 gm. (dry weight) of the seed was used. The
results are given in cubic centimeters of oxygen set free in 10 minutes

at-20° C,
SEEDS AT ROOM TEMPERATURE
DAYS

Dry SEEDS
Hulled seeds Unhulled seeds Unhulled seeds
13.8 5.5 54.0
17.2 17.0 65.2
$ 68.2
15.0 16.25
62.4
SEEDS IN REFRIGERATOR 31 DAYS
Unhulled seeds Unhulled seeds

45.0 46.0

50.8 50.6

45.6 50.0

47-1 49.9

The seeds which were grown in the refrigerator showed less
catalase activity; part of this lessened activity may be due to the
lowered temperature, but part of it undoubtedly was also due to the
fact that the seeds at room temperature had grown slightly more
than those in the refrigerator.

Microchemistry

A brief microchemical analysis was undertaken in order to
locate the materials in the- tissue of the seed, as well as to get an
idea of how much was present (fig. 1).

Practically all of the cell walls gave the blue color reaction with
75 per cent H,SO, and iodine, except the two small regions of the
integument at each end of the caryopsis. With phloroglucin-HCl
a cherry red color was observed in the pericarp integument near

4 Wenmer, C., Die Pflanzenstoffe. Jena. rorr.

1920] SCHERTZ—SUDAN GRASS SEED 81

the micropylar end of the caryopsis.

With acetone and a drop

of concentrated HCl a red color was noted on the pedicel, and
especially was the red prominent in the whole pericarp integu-

ment. This indicated strongly the
presence of methyl pentosan, and per-
haps araban and xylan. No callose

tegument and the cell membranes of
the starchy endosperm gave slight
tests, while the scutellum, plumule,
plumule sheath, radicle, and root
shoot gave a strong reaction, indicat-
_ ing the presence of much pectic sub-
stance. Small particles in the cells
also gave a pectose reaction. The
phloroglucin-HCl tests showed only
traces of lignin, if any, present in the
pedicel and in the glume. Upon
heating the tissues with concentrated
HNO, and concentrated KCIO,, ceric
acid was observed to issue from the
tissues of the pericarp integument.
Suberin was present here.

All cells of the embryo, and espe-
cially the cells of the embryo at the
micropylar end, were rich in oil.
The fat-containing cells of the endo-
sperm stained heavily with Sudan
Ill. Also, the epithelial layer had
some fat present. The whole of the
embryo became red when treated with
concentrated H,SO,, and later took a
greenish hue. Hence, phytosterol
was thought to be present in the

Fic. 1.—Longitudinal section
of grain of Sudan grass: a, glume;
b, pericarp; ¢, aleurone layer; d,
endosperm; e, scutellum; /f, cole-
optile; g, plumule; 4,embryo node;.

i,radicle; 7, root cap; k, coleorhiza;
1, pedicel; m, basal seta; , glandu-
lar layer of scutellum; 9, lodicule.

embryo, and also in a portion of the seed coat at the caine bog’

end of the caryopsis.

82 BOTANICAL GAZETTE [JANUARY

Silicon was found in the pericarp, as was shown by heating a
dry section of the tissues with phenol. Tannins were found in the
glumes and in the outer coats of the seeds, where red and purplish
colors were observed, which were probably due to the oxidized
tannins.

Two sizes of starch grains were found. The endosperm cells
were filled with large sized starch grains, while the pericarp integu-
ment, the pedicel, and the basal seta had smaller grains in them.

Neither dextrin nor glucose was present in the embryo or in the
endosperm, but considerable was present in the hulls. Amzylo-
dextrin was found in all of the endosperm cells in rather large
quantities. The layers of the cells of the caryopsis outside of
the fat-containing endosperm cells all gave a positive reaction for
glucose when treated with copper tartrate and sodium hydroxide.

TABLE VI
MICROCHEMISTRY OF SUDAN GRASS SEED

o woh a g 2
Part of seed 3 3 2 Z 3 € 3 g 4 8 a qi
Lt =] 9a ~~ > s

SP Pe EE tle eo eee
Pedicel oc: +* +)..2.. BE er ieeily yale tae odes eed ee
Hime 5 BN eo ele die ho Peal ya ed eh webs eas his ges f+ |....-
Basal setae ceo he eh ae ee ee es ye eet Se on ee oe
Lodicule tee ON rite Cle ios bs wa or es ae slew Ee saw let ce be ee eee
Pericarp: 2.3. om ss a Se ae Oe mel eee ete | beep eT ag
oe a eybule ea oe a Sey ee oe aeeeels ee pee ee

En + i..... aoe cr eee ee eee es ++ }..... ++
Epithelial k layer. | ee hes yaks sy ee my ge ee” Rar Routines eae ee
Scutellum, 2.4} ces. aan ee ae eae — oe ea ee 6 Oe Wit ren ccueee, Bat
i node nee cae ene + aes er re ne ae
Miche ave. eee es te et ees a ae aaa een AE os aoe
Coleorhiza..... bev ee abies ee ++ me ee ee theo orem Ngai"
famule. 6)... me bees es ee as lowe cs + nts mares ieee Ppa nee
Coleoptile..... . aoe + is Bl a Pte liga cate ess Lina?

* +-=present; +-+=present in large amount.

In conclusion, I wish to acknowledge my obligations to Pro-
fessor WILLIAM CROCKER, under whom this work was done, for his
advice and valuable criticisms; to Dr. S. H. Eckrerson for her
untiring interest and advice relative to the microchemistry; and to
Professor F. C. Kocu for his helpful suggestions in the methods of
chemical determinations involved.

BureAvU OF PLant INDUSTRY
Wasuincton, D.C.

BRIEFER ARTICLES

WILLIAM GILSON FARLOW
(WITH PORTRAIT)

With Dr. Fartow, whose death occurred on June 3, 1919, after a
short illness, there passes not only a unique personality, but one whose
preeminence in his special field was such that to no one else could the
title of cryptogamic botanist, in the broader sense, be so justly applied.
Apart from his extensive fa-
miliarity with other branches
of botany, it is doubtful if
anyone has ever approached
him in his knowledge of the
non-vascular plants as a
whole, a knowledge so com-
prehensive as well as so
detailed, that in matters re-
lating to most of the larger
groups his opinion was rightly
regarded as that of an expert.

Gifted with an extraordi-
narily retentive memory,
exceptional ability, keen dis-
cernment, and sound judg-
ment; appreciating the
necessity for a wide and
thorough training for his
work; possessing, also, suf-
ficient means with which to avail himself of opportunities, many of which
were such as come only to the pioneer, he was able to accumulate books,
collections, and other material needs for the execution of his purposes.
His equipment thus included intellectual and material factors which
combined to make him one of the foremost figures in the botanical world.

Dr. Fartow’s interest in botany had already developed during his
undergraduate days at Harvard, and his natural fondness for the subject
was fostered and developed by his contact with Asa Gray, by whose
$3] [Botanical Gazette, vol. 69

84 BOTANICAL GAZETTE [JANUARY

advice, after graduation, he studied medicine in preparation for a
scientific career. Receiving his Doctor’s degree in 1870, he became
Gray’s assistant, and had the privilege of teaching and studying with
him for two years. Although, during this association, he gained a
comprehensive knowledge of the vascular plants, his preference for the
non-vascular types, and especially the algae, was already apparent,
since it is with the latter that his first two papers, “‘Cuban seaweeds”
(1871) and “List of the seaweeds or marine algae of the south coast of
New England” (1871-1872), are concerned.

Gray’s interests, being primarily systematic, were naturally im-
pressed on Dr. Fartow, and the former evidently contemplated the
conversion of his pupil into a collaborator who might in a measure do.
for the lower cryptogams what he had himself done for the flowering
plants, even to the point of preparing a manual. Although no portion
of this program was carried out, the preparation of a textbook of cryp-
togamic botany was in Dr. FArLow’s mind more or less constantly,
until the idea was finally abandoned in the early nineties. It was partly
with this in view that he was advised by Gray, after serving two years
as his assistant, to visit Europe, come in personal relations with European
botanists, acquire a knowledge of their methods of working and of teach-
ing, and above all to learn as much as possible of the lower forms,
especially the fungi and lichens. He therefore sailed for Liverpool im
June 1872, and went first to Scandinavia, where he saw, among others,
the elder Fries, as well as AREscHoUG and Acarp#H and their herbaria.
He continued his journey as far as St. Petersburg, where he desired to:
see the algae in the Ruprecht Herbarium. Although he also traveled
in Germany, Switzerland, France, Italy, and England, meeting many
well known botanists, he passed most of his time at Strassburg in
DeBary’s laboratory, spending also some weeks in an intensive study of
the lichens with Dr. J. MuLLER at Geneva, and of the algae with BoRNET
and Tuuret at Antibes. DrBary was then professor of botany and
regent of the German University, which had replaced the French Académie
after the close of the Franco-Prussian War, and was reputed to know
more about the fungi, their morphology and development, than anyone
else in the world. Dr. FaRLow was thus able to fill this, the most
serious gap in his equipment, and to acquire, among other things, a good
foundation in general plant anatomy. Here he came in contact with
SCHIMPER, then an old man and the most distinguished member of the
scientific faculty, Graf Sotms, recently appointed ausserordentlich pro-
fessor, and various students attracted by DEBARy’s courses: STAHL,

1920] ' BRIEFER ARTICLES 85

ROSTAFINSKI, SOROKIN, GILKINET, LINDSTEDT, and others. He was
strongly influenced by the personality of DEBAry himself, his wide
knowledge, ability, earnestness, and high ideals of care and accuracy
in scientific work. The training which he thus acquired served as a
fitting complement to that which he received from Asa Gray, the im-
press of whose systematic predilections was thus tempered by DeBary’s
very different point of view. Work of a taxonomic or even of a gen-
eral nature was not encouraged in the latter’s laboratory, and he was
regarded by Dr. FARLOW as somewhat narrow in his conception.of the
scope and extent of the preparation desirable in the preliminary training
of a botanist. He was not himself, however, restricted to a special
topic until more than a year after he entered the laboratory, when
DeBary, having observed the vegetative development of a fern sporo-
phyte from the prothallus, turned the subject over to him for investiga-
tion. The resultant paper, on “An asexual growth from the prothallus
of Pteris cretica,’’ published in the Botanische Zeitung and elsewhere, at-
_ tracted wide attention and interest, and, although it was at first attacked
from all sides, rendered his name familiar to botanists everywhere.

His reputation was thus well established when he returned to America
in the summer of 1874, and was appointed to an assistant professorship
at Harvard, the first special provision in this country for instruction in
cryptogamic botany. For some years he was stationed at the Bussey
Institution, where his work dealt largely with the economic aspects of

mycology, and where he may be said to have laid the foundations of
American phytopathology. During this period of 5 years his published |
papers on fungi were largely devoted to destructive parasites, such as
the black knot, grape mildew, onion smut, etc., although he did not
neglect the marine algae, and published several articles on the algal
‘impurities of water supplies.

In 1879 he was transferred to Cambridge as professor of cryptogamic
botany, a position which he continued to occupy until his death, after a
service on the Harvard faculty of 45 years. He was thus able to devote
himself to the Farlow Herbarium, the nucleus of which was the well
known Curtis Herbarium, purchased during his absence in Europe,
and of his unrivaled library of books, papers, and journals relating
to cryptogamic botany; the development of instruction in different
branches of the subject, as well as of productive investigation on his own
part and that of his students.

In 1883 he instituted the numbered series of “ Contributions from the
Cryptogamic Laboratory of Harvard University,” which, up to the

86 BOTANICAL GAZETTE [JANUARY

time when he retired from active teaching in 1896, included the titles of
some 40 papers, which, with the exception of the four first numbers
written by himself, represent original work accomplished by his students.
Among the latter were included B. D. Hatstep, Wititam TRELEASE,
J. E. Humpnsreys, W. A. Setcuert, K. Mryasr, H. M. RicHarpDs,
and other well known names of American botanists. His own publica-
tions during this period were numerous, and included, for example,
“‘ Monograph of the Gymnosporangia,”’ “‘ Marine algae of New England,”
“Host index of fungi,” etc. Itis greatly to be regretted that his magnum
opus, on selected species of fleshy fungi, for which an edition of very
beautiful plates was printed long before his death, has been left uncom-
pleted.

Although he continued a member of the Harvard faculty until his
death, he withdrew from teaching in the year just mentioned, giving
attention occasionally to advanced students in whose work he felt a
special interest, devoting himself chiefly to the care and increase of the
herbarium and of his library, as well as to the supervision of the extensive

“Bibliographical index of American fungi,” the first part of which,
prepared in collaboration with A. B. Seymour, was published by the
Carnegie Institution in 1905. At the same time he kept up his botanical
reading, about which he was hyperconscientious, and which was varied
and extensive, being by no means limited to matters relating to cryp-
togams alone; while he also carried on a voluminous correspondence,
sparing neither time nor trouble to assist those in search of advice or
information as to identities, synonymy, or literature.

Throughout his life Dr. Fartow was an indefatigable collector, and
his activity of body and keen eyesight, which were little impaired by age,
combined with his long experience and wide and exact knowledge,
enabled him to detect a host of new, rare, or interesting forms. His
annoyance at encountering unrecognizable, and in numberless instances
undoubtedly new, forms, was often very amusing. He had so little
patience with species makers that he himself described but a very small
percentage of the novelties that came in his way. Of those who make a
profession of this type of botanical activity he once said to his class,
“Tf a difference can be imagined, it is a new species; if one can be seen,
it is a new genus.’’ A number of new genera and species were none the
less named in his honor, of which he laughingly asserted that “they
were almost all bad.”

Dr. Fartow’s attainments, his rare ability and learning, commanded
the respect of all who came in contact with him, and were given recogni-

1920] BRIEFER ARTICLES 87

tion by the bestowal of honorary degrees (LL.D. by Harvard, Wisconsin,
and Glasgow, and Ph.D. by Upsala), as well as by his election to member-
ship in the National and Paris Academies of Science, the American
Philosophical Society, the American Academy of Arts and Sciences, the
Linnaean Society of London, and various other scientific bodies in this
country and abroad. His good judgment, keen sense of humor, origi-
nality, and faculty for interesting presentation never failed to render any
public deliverance of his a memorable event.

There are few that have been brought into close relations with him as
students, or in scientific work, whose standards and ideals he did not
fundamentally influence; while those who had experienced his unfailing

indness, thoughtfulness, and sympathetic interest not only regarded
him with the honor and respect due to his character and attainments, but
with a personal feeling of obligation and affection—ROLAND THAXTER,
Harvard University.

CURRENT LITERATURE

NOTES: FOR-STUDERTS

Mitosis in Osmunda.—Cytologists are familiar with the two outstanding
views, associated respectively with the names of GREGOIRE and FARMER,
regarding the method of chromosome reduction. According to the first view

mitosis, a new split functioning in the homotypic. According to the second
view the doubleness is due to a split as in somatic mitosis; bivalents are
formed by a conjugation of segments of this double spirem which separate
in the first mitosis, while the original split functions in the second. A. ve
complete statement of this latter interpretation has been given by Miss DIGBY"
in a new account of mitosis in Osmunda.

In all the archesporial divisions, including the last, the chromosomes
undergo a longitudinal splitting during early telophase. The homogeneous
daughter threads become beaded as the split between them widens, and with
many small connecting strands eventually form a faint resting reticulum which
bears many small granules, and in which the limits of the individual chromo-

mes are indistinguishable. Most of the cements is collected in three or

a number of thin beaded linin threads; these run in parallel airs and are

threads is progressively concentrated, until it takes the form of a double
spirem which segments into split chromosomes. These are separated into
their component halves at anaphase and undergo a new splitting during
telophase. Nuclei may go from the telophase of the last premeiotic division
directly into the heterotypic prophase, or may pass through an intervening
resting stage.

In the heterotypic prophase the reticulum gives rise to beaded “threads”

archesporial prophases. At this stage urs synizesis, during which the
reassociation of the parallel threads to hiss “filaments” is completed. From
the contraction emerges a thick double spirem homologous with the double

* Dicsy, L., On the archesporial and meiotic phases of Osmunda. Ann, Botany
33:135-172. pls. 8-12. fig. 1. 191%
88

©

1920] CURRENT LITERATURE 89

spirem of the somatic prophase; the doubleness is believed to be the result of

loops and the split becomes obscured. During the succeeding stages segments
of the spirem (the “filaments’’), although originally arranged end to end
before segmentation, conjoin laterally in pairs to form the bivalent chromo-
somes, a process which is consummated in the second contraction. It is here
that the conjugation of entire chromosomes occurs, whereas at the first con-
traction (synizesis) daughter halves of chromosomes are reassociated. As the
second contraction loosens, the bivalents shorten and thicken and take up
positions near the periphery of the nucleus (diakinesis). Only rarely. at this
stage can the temporarily obscured split of each component of the bivalent
be detected.

As the bivalent takes its place upon the spindle, its univalent components
become somewhat disjoined, and each again reveals the fission which had its
origin in the last premeiotic telophase and was most conspicuous in the spirem
of the early heterotypic prophases, and which marks the line of separation for
the homotypic mitosis. As the univalent passes toward the pole, its halves
widen out along this line of fission, giving the v-form characteristic of the
heterotypic anaphase. During early telophase each daughter half of the split
univalent undergoes a new longitudinal fission; this is homologous with the
split occurring in the somatic telophase; after being obscured it reappears in

somes occur
archesporial divisions, and during interkinesis the individual chromosomes are
indistinguishable.
he homotypic division is regarded as essentially a continuation of the
ch

telophase; the heterotypic division is consequently an interpolated process
effecting numerical reduction. Although the events of the homotypic division
are ‘‘involved in some obscurity,” they seem to be in the main as follows. The
threads derived from the fission of the daughter halves of the univalent
chromosomes in the heterotypic telophase reassociate in pairs and form a
number of chromatic masses, which later take the form of loosely associated
daughter univalents; these arrange themselves more or less independently on
the spindle. During their anaphasic separation (along the line marked out
in the last premeiotic telophase) the fission which had its origin during the
close of the heterotypic mitosis, and which is to function in the post-homotypic
mitosis, reappears. The chromosomes at telophase take the form of double
beaded threads which establish the resting reticulum as in the archesporial
mitoses.

go BOTANICAL GAZETTE [JANUARY

Although in substantial agreement with the conclusions of FARMER and
Moore,? this interpretation of maturation is directly opposed to that of
GREGOIRE} and YAMANOUCHI,! who hold that the double heterotypic spirem in
Osmunda arises from a conjugation of thin threads, each representing an entire
chromosome, as stated in the first paragraph of this review. The Gr&corRE
school charges the FARMER school with a misinterpretation of the presynap-
tic stages, while the latter charges the former with a neglect of the second
contraction stages. It is not to be denied that the view stated fully by Miss
Dicpy has certain advantages: it allows one interpretation to be placed
upon the double spirem in both somatic and heterotypic prophases, irrespective
of the exact time at which the split originates, and it also helps to explain the
sudden appearance of the split for the second maturation mitosis in the
anaphase of the first.

This question, however, must be settled primarily by direct evidence. It
is obvious that its solution depends upon the exact manner in which the
telophasic transformation of the chromosomes and the derivation of the latter
from the reticulum in prophase are accomplished. It is granted by both sides
that the alveolar or reticulate condition in which the chromosomes are found
in late a is continuous with the similar condition seen in the succeeding
prophas f, abit it is true (1) that the telophasic transformation
fabveabinstioet represents a true splitting, and (2) that the early prophasic
reticulate condition passes directly into the double spirem, it follows that this
doubleness in every prophase is due to the fission which originated in the
preceding telophase, as held by Miss Dicny. Contrary to the statement of
that author, however, workers on mitosis are not at all generally agreed that
the evolution of the chromosomes is that stated in (1) and (2). In his investi-
gation of somatic mitosis in Vicia Faba for the purpose of elucidating —
points, the reviewer,’ contrary to the findings of FRASER and SNELL,' FRASER,’
and others, showed not only that the telophasic alveolization is too irregular
to permit of its being regarded as a splitting, but also that the reticulate
condition of the prophase, instead of developing directly into the definitive
split, gives rise to simple thin threads in which a new split develops. From

2 FarMER, J. B., and Moors, J. E. S., On the meiotic phases in animals and
plants. Quart. Jour. Micr. Sci. 48:489-557. pls. 34-41. 1905.

3 GréGorRE, V., La formation des gemini hétérotypiques dans les végétaux.
La Cellule 24: ph BS pls. 2. 1907.

4 Yamanoucat, S., Chromosomes in Osmunda. Bor. Gaz. 49:1-12. pl. r. 1910.

5’ SHarp, L. W., Somatic chromosomes in Vicia. La Cellule 29:297-331. pls. 2.
1913.

ER, H. C. I., and SNELL, J., The vegetative divisions in Vicia Faba. Ann.

Botany 25:845-855. pls. 62, 63. 1911. :

7 Fraser, H. C. I., The behavior of the chromatin in the meiotic divisions of
Vicia Faba. Ann. Botany 28:633-642. pls. 43, 44. 1914.

1920] CURRENT LITERATURE QI

this it cannot be concluded that in no form does the split develop directly
from the early reticulate structures, or that the telophasic alveolization,
although irregular, may not later become so equalized as to constitute the
first stages of the split; but it does follow that it is quite unsafe to use the
principle of telophasic splitting as a premise from which to draw the conclusion
that the approximation of thin threads in the early heterotypic prophase
represents the reassociation of the halves of a single split chromosome.
Although it is well to emphasize the importance of the premeiotic telophase,
the ultimate solution of this perplexing problem must be reached mainly
through a more refined analysis of those prophasic changes which have led a
long list of investigators to the conclusion that the early heterotypic association
of threads represents a conjugation of entire chromosomes which separate at
the heterotypic division. To the reviewer the figures so far given by the
English cytologists do not prove the theory they advocate.—L. W. SHARP.

Carbohydrate economy of cacti.—A distinct contribution to our knowledge

methods employed give us what is probably the most complete analysis of the
carbohydrates of a single plant tissue that we have, values for no less than
11 different groups of carbohydrates being ascertained, partly by direct
near nene and partly by calculation.
onograph is prefaced by a rather thorough discussion of carbo-
fisticste catch anc in plants, and of the transformations of the carbohydrates
under the influence of acid, alkali, oxidation, and enzymes; and of the energy
relations of the products of these transformations. Then follows a description
of the methods employed. Opuntia phaeacantha and O. versicolor ished
material for the studies. In preparing the tissues for carbohydrate analysis
they were ground in a meat chopper and placed in an oven at 98°C. The
precaution of Davis and Datsx of plunging the tissue into boiling alcohol
was not deemed necessary. The disaccharides and polysaccharides were
hydrolyzed by boiling with 1 per cent hydrochloric acid for 3 hours. All
Sugar determinations were made volumetrically with Fehling’s solution. The
pentoses were determined after fermenting away the hexoses with bakers’ yeast.
The polysaccharides of the cactus are starch and xylan. The mucilage of
Opuntia consists of 34.1 per cent d-glucose and 65.9 per cent I-xylose. Asso-
ciated with it there is probably an acid. Glucuronic acid was found as a con-
Stituent of the sap. The formation of mucilage in a large cells could be
watched under the microscope under certain conditio
The relative abundance of the different groups of i cheisdes and also
of water is profoundly affected by the seasonal variations of the external

POEHR, H. A., The carbohydrate economy of the cacti. Carnegie Institution of
Niasdangtn. Publ. 287. pp. 79. 1919.

g2 BOTANICAL GAZETTE [JANUARY

conditions. From the cool and humid winter to the hot and dry fore-summer
the water content of normal species of Opuntia may change from about 80 to
65 per cent, and then rise again to 83 per cent during the humid but hot mid-
summer. “Low water-content and high temperatures are associated with:
(x) increase of polysaccharides; (2) decrease of monosaccharides; (3) increase
of pentosans. High water-content and lower temperatures are associated with:
(1) decrease of polysaccharides; (2) increase of monosaccharides; (3) decrease
of pentosans.”” The author points out the significant fact that “the greatest
activity of the plant comes at a time when the content of monosaccharides and
disaccharides is highest,”’ in March and April, although he is careful to state
that a relatively large supply of simple sugars is not the only prerequisite for
growth, but is only one of many factors.

n arid atmosphere the cut joints undergo considerable decrease in

of the simple sugars into polysaccharides. Under drought the former decrease,
while the latter and the pentosans increase, in total amount. The author
suggests that the great imbibitional force of the pentosans may prevent the
use of water for hydrolytic processes, when water becomes scarce in the tissue.
These phenomena are closely correlated with temperature effects, when the
latter are studied independently of varying moisture supply. Enzyme
equilibria are discussed in connection with these two factors.

During the night the succulents respire sugar to acids, principally malic.
This is not accompanied by an accumulation of alcohol. In an oxygen-free
atmosphere, however, there is much less acid formed, and a very considerable
amount of alcohol produced. One molecule of malic acid furnishes two of
carbon dioxide and one of ethyl alcohol. Under these anaerobic conditions
more sugar is consumed per unit of energy than under aerobic conditions.
This is accompanied by an increase in the water content of the tissue.

During starvation the joints of Opuntia maintain the same relative pro-
portions of the various carbohydrates. This disproves the theory that the
pentoses are waste products of wehgreaieesaase since x then they mod show an
increase. The water relations of th ing periods
of feeding on sugar solutions are discussed as some length.

SPOEHR advances the theory that the pentoses may be formed ic
glucuronic acid by the loss of a molecule of carbon dioxide, and discusses
isomerism relations between ae hexdaes and ae corresponding pentoses gree
would be formed through th y of g —J. J. WILLAMAN.

Transpiration in tropical rain forests.—The lack of experimental data as
to the conditions of plant growth and activity in tropical rain forests is appat- —
ently leading to some desirable investigation. A notable contribution in this

1920] CURRENT LITERATURE 93

field is by McLEAn,’ who worked in the rich forests on the slopes of the hills
near Rio de Janeiro, Brazil. This is a region of high average humidity, due

months, and to a very considerable amount of cloudiness upon days with no
rainfall. Considerable puarscke data are presented, and a graph of
climatic favorability is devised by combining the four factors of temperature,
rainfall, relative humidity, and sunshine. The curve of this graph seems to
show that the year may be divided into a more and a less favorable period, the
latter extending from June to December.

tmospheric humidity is shown to be high, even outside the forest cover.
Graphs are presented showing the relative range of humidity and temperature
at various levels of the vegetation. The latter records prove that a dense
layer of shrubs divides the forest into two strata, the lower possessing cooler

above. The author believes that this lower stratum is the less favorable to
vegetation, and to it his experimental work is confined.

ranspiration measurements by means of potometers give the water loss
by leaves in the lower stratum of the forest always less than 0.4 of the evapo-
ration from a free water surface exposed alongside the foliage. Experiments
within the laboratory with similar temperature and humidity, but with higher

very slight amount. Structural studies show the intercellular spaces of sun
and shade leaves to be relatively 16.3 and 24.8 per cent, and these amounts
correspond very closely to those found in Europe. The size and amount of
stomata seem to be rather decidedly smaller than that found in typical meso-
phytes of temperate lands. The vascular strands of the shade leaves are much
smaller in cross-structure than those of sun leaves. These data, and the fact
that the author believes the power of root absorption to be low, make it
probable that, even in the protected region of the lower interior of the forest,
transpiration may for short periods decidedly surpass the low capacity of the
ee haceoule water. This i is supposed to account for catinization, semi -
ucculen ts./

Tadee such conditions of reduced transpiration, however, there i is no short-

of mineral matter, but on the contrary the leaves from shaded and pro-
tected habitats show relatively a richer content than do those sun forms with
a much higher transpiration rate. This would prove that here at least the
absorption of mineral salts is quite independent of any transpiration current.

A study of the foliage proves the predominance of the lanceolate leaf form
and a remarkable prevalence of nyctitropic folding, which, however, does not

® McLean, R. C., Studies in the ecology of tropical rain forests; with special
reference to Brazil. I. Humidity. Jour. Ecol. 7:5-54. pl. 1. figs. 21. 1919.

94 BOTANICAL GAZETTE [JANUARY

seem to have a marked effect upon water loss. With the latter phenomenon
is associated an abundance of pulvini.

The report is to be commended as an attempt to apply quantitative
methods in an almost untouched field—Gro. D. FULLER

Heated soils.—JOHNSON” has done a very critical and exhaustive piece of
work on the effect of heating soils at various temperatures on the germination
of seeds and later growth of plants in such soils. The heating at 114-116° C.
was done in an autoclave; at higher temperatures the heating was done with
air-dry soils in dry ovens. The duration of heating was about 2 hours.

Soils heated at 100-115° C. gave temporary retardation of germination and

seedling growth, followed later by a great increase in rate of growth. The
extent of these varied greatly with the soil, seed, and plants used, and with
other environmental conditions. The injury increased as the temperature
rose up to 250°C. As the temperature rose above 250° C. the injury decreased
until it was nil with heating at 350° C. or above. The time of recovery from
the toxic effects was proportional to the intensity of the toxicity. Soils
showed considerable variation in the degree of effect of heating. This variation
cannot be explained on the basis of any one characteristic of the soil, but seems
to result from a combination of a number of its characters.

Seeds varied in their sensitiveness. Lettuce and clover are very sensitive,
and wheat, buckwheat, and flax are resistant. Gramineae and Cucurbitaceae
are usually resistant, while Leguminosae and Solanaceae are more sensitive.
There is great variation in the response of the growing plants. Heated soils
that proved very injurious to some plants, as tomatoes, may be beneficial to
others, as wheat. In general, but not always, there is a parallel between the
sensitiveness of germination and of the later growth of the seedling. Pyronema,
some other fungi, and some bacteria grow best in soils heated to 250° C., and
fall off in growth rate with soils heated to higher or lower temperatures.

The ammonia content of soils is highest in those heated at 250° C., and
diminishes as the temperature of heating rises or falls. The same is true of
the concentration of the soil solution, so that there is a rough parallel between
these characters of the soil and the degree of toxicity or later increased growth.
Adsorptive capacity of the soil modifies the action of the toxic substance. In
soil extracts the toxicity is more nearly correlated with the concentration of
the ammonia. Additions of ammonia to soil produce effects similar to heating.
The author believes the toxic action of heated soils is largely due to ammonia
existing as ammonium eorteaas He thinks other factors are involved in
so-called “chemical” inj

The toxic material in gunn soils is volatile. It is also changed into
non-toxic form when the soil is kept under conditions favoring growth of
organisms. The latter is due to soil flora, and, contrary to PICKERING, does

to N J., The infl Pd SPR ai Ay pee <a 3 Wlnant erawth
OHN £ Ls

oS

Soil Shades 5 7:1-87. 1919.

1920] CURRENT LITERATURE 95

not occur under aseptic conditions. The amount of ammonia apparently may
increase as organisms reduce the toxicity. The ammonia is assumed in this
case to exist in delicate transition stages detected by analysis, but not in toxic
form. The soils heated above 250° C. are supposed to be 2 toxic because
much of the ammonia is volatilized by the high temperatur

The author believes that heating to very high seecoutntes does not change
the quality of the effects gained by heating at ordinary sterilizing temperatures,

them. His results, therefore, are ble in elucid ating the effects of sterilizing
soils by heat.—Wa. CROCKER.

Vegetation of an antarctic island.—Lying 600 miles southwest of New
Zealand, 920 miles southeast of Tasmania, and 970 miles from the antarctic
continent, Macquarie Island is in a position of great isolation. It is little
more than a short range of mountains with peaks ranging from goo to
1424 ft. in height, the length of the island being 21 miles and its breadth less
than 4 miles. The hills descend rapidly toward thé sea, forming bold head-

and precipitous cliffs with no harbors or sheltered bays. It possesses a
remarkably = temperature, the mean maximum being 43°5 F. and the
mean minimum 37°9 F., while the extreme range is only 25°8 F.
of 45 inches is distributed so that no month has less than 3 inches. Wind
velocity is uniformly great, averaging 18 miles per hour.

t has an impoverished vascular flora of 30 seed plants, 3 ferns, and 1
lycopod. Concerning the origin and affinities of this flora, CHEESEMAN™
decides that with the exception of 3 endemic grasses it dates back no farther
than the last glacial epoch. Its repopulation was probably affected through
the agency of birds, as half its species are common to New Zealand, 15 are
found also in Fuegia or South Georgia, and a like number are circumpolar.

The vegetation is characterized by the entire absence of trees and shrubs.
The conspicuous plant forms are the tussock grasses, principally Poa foliosa,
the large leaved ‘‘Macquarie Island cabbage,” Stilbocarpa polaris, an Aralia-
ceous plant resembling a fine rhubarb, the cushion of Azorella Selago, globular
mosses often 4 ft. across, and a purple flowered Composite, Pleurophyllum
Hookeri, with long sage green leaves. Of these the tussock grass is most
abundant, occupying much of the hillside slopes.—Gro. D. FULLER.

Journal of the Arnold Arboretum.—This new quarterly journal has been
established to secure ‘‘the prompt publication of information about trees and
shrubs collected at the Arnold Arboretum,” which was a function of Garden
and Forest (1887-1897). The first number (July 1919) includes the fifth paper
of CaMILLo SCHNEIDER entitled “Notes on American willows” (pp. 1-32);

** CHEESEMAN, T. F., The vascular flora of Macquarie Island. Sci. Rep. Austra-
lian Antarctic Expedition of 1911-14. Series C. vol. 7. pt. 3. pp. 63. map. I919.

96 BOTANICAL GAZETTE [JANUARY

“New species, varieties, and combinations from the herbarium and the collec-
tions of the Arnold Arboretum,” by ALFRED REHDER (pp. 44-60); ‘A phyto-

43); and the fifth paper Ng e S. SARGENT entitled ‘‘ Notes on North American
trees” (pp. 61-65).—J. M

Toxicity of alpha-crotonic acid.—Alpha-crotonic acid, in concentrations of
25-50 p.p.m., is very toxic to wheat plants. Its toxicity is markedly reduced
by the phosphate radical, as SKINNER and REID” show by using it in water
cultures of wheat with a three-salt medium varying according to the triangle
system. The crotonic acid does not affect the relative absorption of any one
salt, thus differing from some of the other toxic organic compounds studied in

INER’S laboratory. The real nature of the antagonism is not known.—
J. J. WILLAMAN

New genera.—Nakar® has described a new genus of Oleaceae (A belio-
phyllum), found in Corea. It is an endemic and related to Fontanesia
(Fraxineae), a monotypic oriental genus.

PENNELL" has described a new genus of Onagraceae (Peniophyllum), based
on Oenothera linifolia as the type. In a conspectus of Kneiffia (Oenothera)
he recognizes 13 species, 4 of which are described as new.—J. M. C

Plant mucilage."*—The mucilage in cacti, mallows, tragacanth, and lilies
arises in special large cells by hydrolysis of the cellulose wall, a hydrocellulose
being an intermediate stage. These walls are not secondarily thickened. An
account is given of the reaction of these mucilages to various stains.—J. J.
WILLAMAN.

Germination.—RussELL” finds that the germination of camphor seeds in
the commercial seed bed is greatly improved by removing the pulp. By pulping
the seeds the increase in the number of seeds of transplantable size amounted
to 60 per cent.—Wwa. CROCKER.

“SKINNER, J. J., and Rem, F. R., The influence of phosphates on the action of
alpha-crotonic acid on plants. Amer. Jour. Bot. 6:167-180. 1 .
3 NAKAI, TAKENOSHIN, Genus novum Oleacearum in Corea media inventum.
Bot. Mag. Tokyo 33:153, 154. I9I9.
4 PENNELL, F. W., A brief conspectus of the species of Kneiffia, with the character-
ization of a new allied -cikeeun Bull. Torr. Bot. Club 46:363-373. 1919. ,

*s Lioyp, F. C., Origin and nature of the ee in the cacti and in certain other
plants. yy Tour: ey 6:156-166. 1919
% RussELL, G. A., Effect of removin ilp from rmination

and the subsequent erik of the py ee Agric. Research 17: ab 1g19-

VOLUME LXIX NUMBER 2

THE

BOTANICAL”: GAZETTE
FEBRUARY 1920

FORMATIVE EFFECT OF HIGH AND LOW TEMPERA-
TURES UPON GROWTH OF BARLEY: A CHEMICAL
CORRELATION

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 259
H. L. WaLsTER
(WITH EIGHTEEN FIGURES)
Introduction

Cereals are commonly considered cool temperature crops.
Cool seasons are known to favor cereal production, warm seasons to
hinder cereal production. Physiologists have correlated these
observations with the general effects of temperature upon the
growth and maturation of the crop, but have given little attention
to possible effects of the initial germination temperature upon the
subsequent course of development of the plant. The investigation
here reported is a study of the effects of high and low temperatures
and concomitant variations in the supply of nitrogen, phosphorus,
and potassium respectively upon the course of development of the
barley plant. A chemical correlation has been established between
temperature and nutrition effects.

Literature

ADERHOLD (1), working with young kohlrabi plants, noted that
exposures of the young plants to temperatures of — 2° C. to —8°C.
for 8-10 hours tended to cause the plant to shoot into flowering
instead of forming the desired “ball.”

mL

98 BOTANICAL GAZETTE [FEBRUARY

GutzeEIt (5) repeated ADERHOLD’s work and found by a rather
extensive set of experiments that exposures to temperatures below
zero had no effect on stem or shoot production in kohlrabi, beets,
or various other plants. He did find, however, that a period at
+ 4° C. during germination and early growth caused about 30 per
cent of certain beets to produce shoots very early the first year.
Some of the shoots produced only very short stems, and the plants
were otherwise normal, while other shoots grew continuously and
early produced flowers and seeds. Beets of exactly the same kind
when kept at +22° C. during germination and early growth showed
no shoot production the first year. Only such beets as were pre-
disposed to early shoot production could be thus forced by low
temperatures, so hereditary characters as well as temperature enter
in as determining factors. GUTZEIT suggests that this temperature
response explains why early seeding of beets causes much premature
shoot production, whereas late seeding gives little or none. On
the basis of other experiments conducted by himself, as well as
data from the literature, GutzE1T concludes that low temperatures
during germination and early growth favor stem formation, while
high temperatures at this time inhibit stem formation.

AppEL and GassNER (2) noted in the experimental fields of
summer cereals at the Agricultural Experiment Station at Dahlem,
Germany, a peculiar sickness, the plants becoming light green, and
the older leaves turning yellow. Since neither animal nor plant
pests seemed to be attacking the cereals, an explanation for their
condition was sought in unfavorable soil and weather relations.
Greenhouse experiments conducted by Appet and GassNER led
them to attribute the peculiar conditions of these summer cereals
to a too high germination temperature.

They grew barley in pots in the greenhouse, keeping one lot at
20-25° C. and the other lot at 5~7°C. When the plants at the
higher temperature had reached a height of 15 cm., those in the
cool house had just come up. Both sets were then transferred to
the open and kept under like conditions. After three weeks the
barley plants from the warm house began to show signs of injury,
the older leaves yellowing at their tips, and only the youngest
leaves remaining green. The barley plants from the cool house

Nevin eta. Swipe Es ET eg! a

ee ee te ee ee

1920] WALSTER—BARLEY 99

soon outstripped the high temperature plants, finally reaching twice
the size. Figures of APPEL and GASSNER’s plants show that there
was an excessive leaf production and little stem production at the
higher temperature. These investigations suggested that the
light color of the leaves was due to nitrogen hunger, but they were
unable to get any beneficial results from nitrogen fertilization.
The addition of iron salts also had no favorable effect.

' GASSNER (3) has made extensive observations and experimental
studies upon the growth and development of cereals in subtropical
climates, the experiments being carried out in the phytopathological
experimental fields of the University of Montevideo, Uruguay.
In considering the choice of varieties of summer cereals suitable
for cultivation in Uruguay, he emphasizes the importance of temper-
ature in the early stages of development, and suggests that decreased
yields are often due to the lack of the necessary cold requirements
(Kalteanspriiche) in the early stages of growth. GAssNER quotes
HELLRIEGEL (6) on the temperature relations of small 4-rowed
barley. H®ELLRIEGEL maintained that in the first half of the
vegetative period of the barley, the period of leaf and culm forma-
tion, an average daily temperature of about 15°C. is the best,
whereas in the second half of the vegetative period, the period of
head development and grain formation, a temperature of 17—18° C.
is the most favorable. HELLRIEGEL therefore insists upon two
different temperature optima in development of barley, the line of
demarcation between the two optima being placed at the time of
shooting.

GASSNER summarizes his views as follows (translated from the
original article) :

We can therefore say that for winter cereals, as well as for summer cereals,
the yield of a given variety of a cereal in a given climate is among other things
dependent upon the influence of the climatic factors in the first stage of develop-
ment in such a way that varieties of high “cold requirements” in their youth
require a colder climate than varieties with lower “cold requirements,” and
that incomplete fulfillment of these requirements causes bad development and
depression of the yield.

GASSNER states that the death and yellowing of the leaves of
young plants previously described by ‘AppEL and GASSNER rarely

100 BOTANICAL GAZETTE [FEBRUARY

occurs in Uruguay. He notes, however, that the culm habit in
Uruguayan oats and rye germinated at high temperatures is dis-
tinctly recumbent, whereas it is upright from the beginning in the
case of plants grown from seeds germinated at low temperatures.
The low temperature plants begin the formation of the culm (shoot-
ing) much earlier than do the high temperature plants. A typical
experiment with oats is outlined as follows:

li Temperature during Date of transfer
Date of ing germination into field

Beginning shooting
January 18 January 18-23,6-9°; January 25 March1i5
anuary 23-25, 25°
January 18 January 18-20, 25°; January 23 No shoot formation on
January 20-25, 6-9° April 25, shooting not
expected before
October

In another series it was found that even 24 hours of exposure
to a germination temperature of 25° led to the same abnormal
course of development as indicated in the second series here quoted.

GASSNER and GRIMME (4) have made one attempt to correlate
the effects of germination temperatures and the resistance of cereals
to frost injury. They analyzed the first leaves of winter and spring
rye germinated at 5-6° C. and at 28°. They found that the seed-
lings germinated at the lower temperature had a higher sugar con-
tent than seedlings germinated at the high temperature; moreover,
seedlings of a hardy winter rye had a higher sugar content than
those of a spring rye grown under the same conditions. Their
results with rye are shown in table I.

HvuTCHESON and QuaNnTz (7) conducted experiments on the effect
of greenhouse temperatures on the growth of the small grains:
wheat, oats, barley, andrye. All four crops were grown under four
temperature conditions, namely, 14.4° C., 16.6° C., 18.3° C., an
23.9°C. The higher temperature range had a distinctly detri-
mental effect upon the growth of the barley and a less harmful
effect upon the growth of wheat and rye, while oats had a normal
course of development at all the temperatures used, although the
oat culms were weaker at the higher temperatures. The high

1920] WALSTER—BARLEY 101

temperature barley plants showed an excessive development of
tillers and no indication of ever heading. Inspection of the figures
shows that the leaves of the high temperature plants were abnor-
mally long, and especially so in the case of the barley. The general
growth characters obtained by HutcHEson and QuANTz were
obtained in the present investigation in the case of high tempera-
ture, high nitrogen series (fig. 13). These authors grew the grain

TABLE I
SUGAR CONTENT OF FIRST LEAVES OF RYE* (PERCENTAGE OF DRY WEIGHT)
er GERMINATION TEMPERATURE 28°C.
SERIES NO. | TOTAL SUGAR
Reduci Non-reduci Reduci Non-reduci
— pip hencnacy nS) Total varie ar ae
Petkuser winter rye
| ea eee 42.19 34-93 7.26 40.92 32.56
ce ENO eae 43.14 35.86 7.28 39-79 31.14 8.65
fg ese 41.92 34.84 7.08 39.13 31.08 8.05
EV ee 42.31 35-85 6.46 40.73 33-94 6.79
ESCO er 40.97 32:31 8.66 39.52 34.11
Petkuser spring rye
LESS ma 36.58 29.41 oe ee 5H 24 43 4.44
a eae ee 37.08 30.57 6.51 33.20 26.58 4.68
Bee 35.30 30.41 4.98 32.50 26.81 5.78
9, a ete 37.65 31.02 6.63 34.56 30.38 4.15
Ee ae 35.85 40,27 5.64 32.94 28.16 4.78

* Similar results were obtained with barley.

in 4-inch clay pots, two plants to the pot. No mention is made
concerning the substrate used in their experiments.

This investigation of the influence of high and low temperatures
upon the growth of barley was planned to ascertain in particular
the influence of variations in the supply of nutrient salts with
concomitant variations in the temperature. The nutrients varied
were nitrogen, potassium, and phosphorus. Chemical analyses
were made in order to relate certain observed differences in growth
to possible differences in the chemical composition.

102 BOTANICAL GAZETTE [FEBRUARY

Method
CULTURE SOLUTIONS

The method of sand culture was used throughout these experi-
ments, the sand ‘used being a highly pure Ottawa silica sand obtained
from Ottawa, Illinois. Two gallon glazed stone jars were used as
the culture vessels, each jar receiving 11.4 kilos of sand. The
water content of each jar was maintained at approximately 13 per
cent of the dry weight of the sand by means of frequent weighing.
’ Tottingham’s culture solution was used in diluted form. This
solution has the following composition:

KNO,—0.0034 M (0.3437 gm. per liter)
Solution A: ( KH,PO,—0.0108 M (1.4692 gm. per liter)
MgSO,—0.0081 M (0.9750 gm. per liter)

Solution B: Ca(NO,),—0.0101 M (1.6573 gm. per liter)

Enough of these salts to make too liters of culture solution
were dissolved and made up to 2 liters, the Ca(NO,). being made
up in a separate 2-liter portion in order to prevent precipitation
of insoluble calcium salts in the highly concentrated solution. The
mixture of these two solutions was designated solution A B, and
7.5 cc. of each of these solutions were added to 1500 cc. of distilled
water for the initial dose of nutrient solution. This quantity of
nutrient solution was applied to the jars designated in the outline
of the scheme of the experiment at the time of planting (March 1).
In addition, 0.01 gm. of FeCl, was added to each culture one
week after sowing. On April 4 each A B culture received a second
dose of 7.5 cc. of this normal nutrient solution. All cultures"
receiving only AB solutions will be referred to hereafter as.
“normal.”

Solutions lacking in P, N, and K were also made. The amount
of salts indicated in the respective tables were dissolved and made
up to 2000 cc. with distilled water; 75 cc. of these solutions made up
to 1500 cc. were used as initial doses. Similarly, solutions were
made up in which the P, N, and K were supplied in one-fourth the
concentration of that found in solution A B.

1920] : WALSTER—BARLEY 103

Solution C lution F
(lacking in phosphorus) (nitrogen in Peermon concentration)
3.437 gm. KNO, 0.8592 gm. KNO,
8.8561 gm. KCl 2.0422 gm. KCl
23.855 gm. Ca(NO,)., 4H.0 14.6923 gm. KH.PO,
19.789 gm. MgSO,, 7H.0O 19.7890 gm. MgSO,, 7H.O
4.1432 gm. Ca(NO,)., 4H,O
(ghoanboras in poles 2 tration) 9.264 gm. CaCl, 2H.O
3-437 gm. KNO; Solution G
3.873 gm. KH,PO, (lacking potassium)
6.642 gm. KCl 2.8894 gm. NaNO,
23.855 gm. Ca(NO,)., 4H,0 17.0692 gm. Na,HPO,, 12H.O
19.789 gm. MgSO,, 7H.0 | 23.855 gm. Ca(NO,)., 4H,O
19.789 gm. MgSO,, 7H.O
olution E
econ nitrogen) .
Solution H
2.723 gm. KCl (potassium in one-fourth concentration)
14.6923 gm. KH.PO, 0.8592 gm. KNO,
12.353 gm. CaCl, 2H.O 2.1671 gm. NaNO,
19.789 gm. MgSO,, 7H,0 3.873 gm. KH.PO,

12.8019 gm. Na,HPO,, 12H,O
19.789 gm. MgSO,, 7H.O
23.8558 gm. Ca(NO,)., 4H,O

To certain of the AB cultures extra doses of N , ee SO. Ey
alone, and in all possible combinations, were added in the amounts
and at the times indicated in the schematic outline. These extra
doses were supplied in the form of solutions of NaNO,, KCl, and
Na,HPO,, 12H.O respectively. All cultures were run in triplicate.
Certain of the replicates in each set of triplicates received a modified
supplementary treatment, as indicated in table II, the letters N, K,
and P indicating NaNO,, KCl, and Na, HPO,, 12H.0 respectively.

Oderbrucker barley (Wisconsin No. 5) was seeded March 1.
About 30 seeds were sown per culture, the cultures being thinned to
25 plants per culture. This heavy seeding was purposely chosen in
order to prevent tillering, so that the course of development of a
plant with a single culm could be followed.

TEMPERATURE AND HUMIDITY CONTROL.—The temperature of
the greenhouses was controlled by means of automatic thermo-
regulators. The lower temperature selected was 15° C., the higher
temperature 20° C. The degree of control obtained is shown in

104 BOTANICAL GAZETTE [FEBRUARY
TABLE II
OUTLINE OF GREENHOUSE EXPERIMENTS
Jar no.* General treatment Supplementary treatment
64, be a, ee SRR WCE aE ie Vv Ai Ci de
45h ee one ee ae, BOE OO ee ES DID peeping ara mene ra eon, eer mr
et oa. Solution C 2 gm. P added April 27
8, “* ° .
be “4 oa bir Solution D 1 gm. N added April 26
10, II, 12 : ;
aie 3 eee Solution A B 1 gm. N added April 26
13,14, et pura Solution A B+1 gm. P Second dose of 1gm. of P added
76; 77, 78 arch 30
ae x7\ eee hve INE ae ee cy eet datas 3 een es
oo Solution E 4 gm. N added April 27
82 aut Sait as EE ee Cee ae are eee
83 dan ieee ks Solution F 4 gm. N added April 27
at? Solution AB-+1gm.N_ | Secondd h
Surette gm. econd dose of 1 gm. of N on March 20;
Scie third, dose of 2 gm. on April 26
24 : fourth dose of 2 gm. on April 2
a Se ean Solution A B+1 gm. N Second dose of 1 gm. of N on Starch 30
26.20, 2 . “
5 He au pe Solution A B 1 gm. N added April 26
28, 30 ; ‘
or. : oh Piven Solution G 1 gm. N added April 27
4 Te ee Solution G 1gm. N added April 27; 2gm. K
page added April 2
rae ie 4 ee Solution H gm. N added Apsil 27
?
34, ead :
oF, 98, 99 ans Solution A B 1 gm. N added April 27
37, 38/39 ,}-+-| Solution A B+1 gm. KCl Second dose of x em. K: March 30
pple freee Solution AB+1gm.N, | Second dose of 1 gm. N and 1 gm. P
eat 1 gm. P March 30; thi eg ae
April 26; 2 gm. N only April 29
oF eek Solution A B+1 gm. N, | Second dose of 1 gm. N an
1 gm. P March 30; 1 gm. and 2 gm. P
43,45 ez’
: 06 ie } Daa Solution A B+1 gm. N Second dose of 1gm. N March 39;
rg 7 third dose of 1 gm. N April 26
4) A Peete as Solution A B+1 gm. N Second dose of 1 gm. N April 26
” gener Solution A B+1 gm. P, | Second dose of 1 gm. of P yet 1gm. K
Coe 1 gm. K March 30; 1 gm. N April 2
BO 80i occ Solution AB+1gm.N_ | Second dose o id dove ra gm. K

|

1920] WALSTER—BARLEY 105

TABLE II—Continued

Jar no. General treatment Supplementary treatment
ek cat Cea e Solution A B+1 gm. N, peces dose of 1 gm. N and 1 gm. K
1gm. K arch 30; 1 gm. N and 2gm. K
ril 26

52,5354 \ | solution AB-+1 gm. P Second dose of x gm. P March 30;
gm. N April

115,116, 117) 6
spi Solution A B-+1 gm.N, | Second dose of 1 gm. each of N, K,
I I Py n h 30; of 2gm each
pril 26; 2 gm. N April 29
45 pics Solution A B+1gm.N, | Second dose of 1 gm. each of N, K,
1 gm. P and P March 30; 1 gm. Nand 2gm.
58,59 | : each of K and P April 26
aan 123f 00 t Solution AB+1gm.N, | Second dose of 1 gm. each of N and P
: I gm. P a QO; 33 more of each
pril 26; 2 gm. of N P 29
ee Sn a rae Solution AB+1gm.N, | Second dose of 1 gm. each of N and P
1 gm. P March 30; 1gm. N and 2gm. P
61, 62 ; April 26
124 he oe er Solution A B+2 gm. P, Second dose of 2 gm. P and 1 gm. N
: 1gm.N arch 30; si, 5 oe 2gm. N

sais ee ceo Solution AB+2gm.P, | Second dose of 2 gm. P and 1 gm. N
1gm.N March 30; 4gm. P and 1gm. N
April 26

* Jars nos. 1-63 inclusive kept in warm greenhouse; jars nos. 64-126 inclusive kept in cool greenhouse

the thermograph records obtained in the two houses (figs. 1, 2).
It will be noted that there was a fairly satisfactory degree of control
up to about the middle of April, at which time (April 19) the samples
for chemical analyses were taken. So oe fluctuations came
at about noon; a considerable temy ce always existed

The dade of humidity was not under a complete control as
desired, the evaporation rate averaging somewhat higher in the
warm house. It is possible that some of the differences noted in
chemical composition are due to the higher evaporating power of the
air in the warm house. This higher evaporation rate was, of course,
a function of the higher temperature. -

Observations on growth of barley cultures :
During the first two weeks of growth the plants in the warm
house, which were several inches high before the plants in the cool
house had come up, maintained a more rapid growth rate. The
first leaves of all of the plants in the warm house, except those
receiving little or no nitrogen, tended to lop over. The low

sisXyeur [voruoys 105 Suydures jo out, 07 Zuuyd wosy asnoy ooo ur ainjvsieduie} sre Sutmoys spsodes Yduasouusy.[— I “oly

De
s
=
S
|
PY
bony
:
w
RQ.

sisA[wue [voTUIdYD 105 Surjdures Jo out) 0} Burjurd woay asnoy WAV ut ainjeseduis} ALv BuLMoYs spi1ode4 YdvsZouL9y | —z “OT

Ss
f
NX
|
ne
iB
=
=

108 BOTANICAL GAZETTE [FEBRUARY
nitrogen leaves were in every case stiff and upright.
the ‘‘no phosphorus”
ciency.

By March 16
series began to show the effect of the defi-
The “‘no potassium” series in the warm house showed the

TABLE III
ee OF LEAVES (BLADE
CO PA

AND SHEATH) AND STEMS IN
TS OF TOTAL PLANTS,

BASED ON GREEN WEIGHT

Leaves (blades Stine

Culture no. and treatment go cw cing Percentage
440. igh NO wart: 92.95 7.05
24. aN WATE ec ob 88.23 1°73
o. High PandN warm..... 96.87 +44
108 i sch ee ere 69.20 30.80
a. OP IN COOL cl... 65.68 34.32
104. High P sid | < Goole ees 71.37 28.63

greatest lopping over on March 16. About April 1 the plants in
the cool house began to outstrip the plants in the warm house in
their growth rate, and in particular in their tendency to maintain
an upright growth habit. The total amount of tissue formed at

G. 3.

—Nitrogen series, cool house: note vigorous upright condition of no. 85
4).

as pbc?) with sprawling condition of no. 23 (fig.

the higher temperature was about the same, but it was differently
distributed, as will be apparent from the data given in table III.

By April 19 all plants in the cool house had outstripped those in
the warm house. The most striking difference between the two

1920] WALSTER—BARLEY 109g

houses was the maid condition of the high nitrogen cultures in
the warm house, in contrast with their upright condition in the
cool house. Figs. 3-15, taken April 24, show the condition of the
barley on that date.

Fic. 4.—Nitrogen series, warm house

Fic. 5.—Phosphorus series, cool house: N and K treatment of nos. 68, 71, 75,
and 78 ‘ndtmaal” (same as no. 89 in

Figs. 16-18, taken May 16, show the failure of the high nitrogen-
high temperature plants to mature normally. Such shooting as was
obtained at the higher temperature was due, in the opinion of the
Writer, to inability to control the moisture supply, because of very
great fluctuation in the temperature as the spring season advanced.
The writer believes that had it been possible to control absolutely

IIo BOTANICAL GAZETTE [FEBRUARY

temperature and moisture supply, the high nitrogen-high tempera-
ture series could have been maintained in practically continuous
vegetation without any tendency to reproduce. The reason for
this belief was the failure of this series to produce any stem (culm)
until the water supply fell below the normal previously maintained.

Chemical examination of tissues

In order to ascertain, if possible, the character of the internal
processes that determine this very striking formative effect of the

—Phosphotus series, warm house: N and K treatment of nos. 6, 8, 12, and

Fic. 6
15 “normal” ee as No. 25 in fig. 4).

higher temperature in the presence of high nitrogen supply, tissue
analyses were made on the leaves (blades plus sheaths) from 100
gm. of total plants from cultures nos. 44, 24, 108, 87, and 104.
_ The plants were selected so that the sample equaled 100 gm.
Table III shows the very low percentage of stem material at the
higher temperature. Since both leaf-blade and leaf-sheath are
active organs in cereals, both were included. The second column
in the table shows the green weight in grams of this leaf tissue.
The first column in table VI shows the date and hour of taking these
samples.

1920] WALSTER—BARLEY III

METHODS OF TISSUE ANALYSIS
The green samples were weighed and immediately preserved by
adding enough ethyl alcohol to make a 75 per cent alcoholic solu-
tion, and then boiled to arrest enzymic activity. The preserved

Fic. 7.—Potassium series, cool house: N and P treatment of nos. 92, 94, and 100
same as no. 8g in fig. 3; note sprawling condition of “‘no potash” culture.

Fic. 8.—Potassium series, warm house: N and P treatment of nos. 29, 32, and 38
Same as no. 25 in

material was then subjected to the method of tissue analysis devised
by Watpemar Kocu, and modified by F. C. Kocu (8). The
method used consisted essentially of 4 hours’ extraction with hot
ethyl alcohol in a continuous extractor, followed by 1 hour’s

I12 BOTANICAL GAZETTE [FEBRUARY

extraction with ether, then treatment of the finely ground material
with hot water several times, after which the aqueous mixture was
made up to a concentration of 75 per cent alcohol and filtered.
The insoluble material was then subjected to further extraction
with hot alcohol for 24 hours.

The combined extractions were evaporated to dryness on a
steam bath, then repeatedly evaporated with absolute ethyl
alcohol in order to remove water. The dry hard residue was then

Fic. 9.—Effect of heavy N fertilization: no. 12, normal N (warm house); no. 85,
heavy N (cool house); no. 22, heavy N (warm house); no. 75, normal N (cool house).

extracted with anhydrous ether by grinding with a pestle with suc-
cessive portions of fresh ether: The ethereal extracts were made
up to 250 cc., and then divided into suitable aliquots for chemical
and dry weight determinations (50 cc. portions). This extraction
was designated as fraction 1 (F,). The ether-insoluble residue
was taken up in about 65 per cent alcohol and made up to a volume
of 500 cc., 50 cc. portions being taken as aliquots for analysis and
dry weight determinations. This was designated as fraction 2 (F.).
Moisture determinations were made on duplicate F, and F, aliquots

1920] WALSTER—BARLEY 113

by evaporating almost to dryness on the steam bath and then
taking down to constant weight in a vacuum desiccator.

TABLE IV
EFFECT OF TEMPERATURE cae AMOUNT AND PERCENTAGE OF DRY MATTER AND
ATER IN BARLEY LEAVES

Green Dry. weight | Weight of ——— Percentage

Culture no, and treatment : eight pa be (gm.) waser of oy

44. High N warm........ 92.05 12.67 80.28 86.36 13.64

24, “Big N: owatm: 3 88. 23 12.79 75.44 85.50 14.50

41. High PandN _ warm.. 96.87 IT16 85.77 89.47 10.53

108. High N = Res 69.20 10.92 58.28 84.21 15-79
87. High N. cook. 33*. 65.68 10.23 55.45 84.42 15.58

104. High P aAd N cool..... 71.37 IT.04 60. 23 84.30 15.61

Material insoluble in ether, alcohol, and water was designated
as fraction 3 (F;). This entire fraction was dried to constant weight

Fic. 10.—Influence of supplementary P fertilization on heavy N fertilization:
all salen received equal heavy doses of ; in form of NaNO,; ages nos. - and
104 recei rte pacers dosage of extra P; nos. 41 and 44 OS. 104
and 108 in cool house; P failed to coumeniet FA of N at higher pid aig,
chemical Gaiyess made of leaves from this set of cultures.

at too° C. in an electrically heated oven. Table IV gives the
relative proportions of moisture and dry matter in the several
samples analyzed.

II4 BOTANICAL GAZETTE [FEBRUARY

Table V gives the distribution of the several fractions in the
samples analyzed. - Particular attention is directed to the fact that
the temperature does not seem to have any important effect upon
the proportion of lipins (F,), except where extra phosphorus is
present, in which case a high temperature led to an increase in the
lipin material. The author regrets not being able to confirm this

Fic. 11.—Influence of supplementary K caper on heavy N gooene
nos. 50 and 113 recéived equal heavy doses of N in form of NaNQ,; n
received only ‘‘normal’’ N; all 4 cultures received equal eek doses ay K in form of
KCl; nos. 50 and 38 warm house; nos. 100 and 113 cool house; K failed to counter-
act effects of N at higher temperature.

interesting observation by means of further analyses. The pro-
portion of fraction 2, which might quite properly be designated the
metabolic fraction, averages about 10 per cent higher at the higher
temperature. The proportion of fraction 3, or storage and skeleton
fraction, averages nearly 8 per cent higher at the lower temperature.

F, was analyzed for total N and total P. F, was analyzed for
total N (organic and ammoniacal only), total P, direct reducing

1920] WALSTER—BARLEY II5

sugars, and for total sugars after mild hydrolysis. Samples 24
and 87 were also analyzed for inorganic phosphorus, using the
PowicK-CHAPIN (10) method. F, was analyzed for total N,
total P, N and P soluble and insoluble in 1 per cent NaOH, phos-
phoprotein phosphorus, polysaccharides, and. cellulose, etc., by

TABLE V

EFFECT OF TEMPERATURE ON DISTRIBUTION OF EXTRACTIVES AND INSOLUBLE MATTER
IN BARLEY LEAVES -

Soluble in Soluble in hot Insoluble in ether,

Culture ba. and treatnent avi abet alcohol and water | alcohol, and water
Percentage Percentage Percentage
44. HighN warm......... 8.699 33.017 : 58.284
24. HighN warm......... 7.885 33-743 58.372
41. High PandN warm... 10. 433 32.613 56.954
108. High N es pees 8.251 30.33% 61.428
$7. High NW reek cs ae 8.663 27.823 63.514
104. High P wid No cook 2.5 7-681 : 30.279 62.040

difference. The following list gives the methods employed.
The details of the several methods are those pecmmamended by
Kocu (8) and MatHEws (9).

Total nitrogen....:..... Arnold-Gunning method.

Total phosphorus. ...... Neuman-Pemberton method.

Direct reducing sugars... Bertrand volumetric method (glucose calculated from
Munson-Walker tables in MATHEW’s Physiological

Chemistry).
Total suger Bertrand volumetric method applied to the products
of mild hydrolysis with HCl.
Polysaccharides......... Bertrand volumetric method applied to the products
of strong hydrolysis with HCl.
Phosphoprotein
phosphorus. .....:..... Determination of the P precipitable by Mg mixture

in an extract made by 48 hours’ digestion with
1 per cent NaOH at 37-40° C.

The method for phosphoprotein phosphorus is based upon the
discovery by PLIMMER and Scott that phosphoproteins can be.
separated from nucleoproteins through hydrolyzing the former
with 1 pe»cent NaOH, the latter being unattacked by the dilute

116 BOTANICAL GAZETTE [FEBRUARY

alkali. The exact details of the method used on this material are
as follows. Weighed samples of F; were placed in 300 cc. Erlen-
meyer flasks, usually about 0.5 gm., and 1 per cent NaOH, free
from phosphorus, was then added at the rate of 100 cc. of NaOH
for each 1.0 gm. of substance. The flasks were stoppered and
placed in an electric incubator at 37-40° C., where they were allowed

Fic. 12.—Influence of supplementary fertilization with both K and P on heavy

N featiiaes: no. 120, heavy N+extra K and P, cool house; no. 47, “‘normal’? N+

extra K and P, warm house; no. 55, heavy N+extra K and P, warm house; no. 110,

“normal’’ N-+extra K and P, cool house; note that complete fertilizer’’ failed to

counteract effects of heavy N at higher temperature; are not growth effects noted in
no. 55 referable to stimulus received at time of germination ?

to remain 48 hours. The flasks were shaken about 4 times each
day. At the end of the digestion period the insoluble material
was filtered off on ashless filter papers and carefully washed with
lukewarm water. The combined filtrate and washings were then
neutralized to litmus with acetic acid and the PO, ions precipitated
with magnesia mixture in the presence of an excess of NH,OH.
This precipitation was conducted at a low temperature, the solutions

1920] WALSTER—BARLEY IT7

being allowed to stand in the ice box for 24 hours. At the end of
the 24 hour period the magnesium ammonium phosphate was
filtered off, washed with 2.5 per cent cold ammonia water, dissolved

—Influence of — in yonaecengh in warm house: N, K, and P indi-
cate ‘had fertilizer dosage is in excess of “‘normal” A B solution; eathiee noni scouts
shown in fig. 14, where ‘valli scat is Montiel but temperature low

Fic. 14.—Influence of variation of fertilization in cool house: contrast with fig. 13
in dilute nitric acid, and the phosphorus then precipitated by means
of the molybdate solution. Final determination of the phosphorus
was made by means of the Pemberton alkalimetric method.

118 BOTANICAL GAZETTE [FEBRUARY

In order to determine whether or not the material thus extracted
by 1 per cent NaOH contained any forms of P not precipitated by
magnesia mixture, the phosphorus was determined in the insoluble
residue. Similarly total N determinations were made in the in-
soluble residue from another set of determinations. The difference

15.—Influence of extra heavy supplementary P fertilization on heavy N

fectieaion: no. Sia eavy N and heavy P (warm house); no. 125, heavy N and
extra heavy P (cool iia): no. 104, heavy N and heavy P (cool house); no. 63,
eavy N and pe heavy P (warm house).

between total P (or N) soluble in 1 per cent NaOH gave the P (or N)
present in the NaOH extract.
TABLE VI

EFFECT OF TEMPERATURE ON ACCUMULATION OF SOLUBLE CARBOHYDRATES IN BARLEY
sy (RESULTS OF ANALYSIS OF F,)

T Ss zS3 z 5
Dmecr revucinc| *OTAL SUGARS | 9-53
SUGARS (AS a ae 262
HYDROLYSIS zaze
GLUCOSE) gwOoOR
(AS GLUCOSE) SHSae
CULTURE NO., TREATMENT, AND TIME OF SAMPLING re 4 3 Z of
Z oF
Percent-| Percent-| Percent-| Percent-| § z BRS
age F, | agetotal| age F; | agetotall *OaROF
leaf leaf | &
44. ., April 24, 1918 warm....... 15.99 5.27 20.41 9.71 0.15252
24. Heh N ei April 25, 1918 warm....... 19.83 6.60 26.84 9.° 0.15342
41. dn Hager Bl p.M., April 25, 1918 warm..! 10.62 3.40 18.55 5.05 | 0.00535
108. His M., April 24, 1618 . cool... ...... 20.20 6.11 45.79 13.88 0. 26007
87. EN Pioor pril'24,; r9%8 cool... ...:. 23.17 6.44 36.90 10.29 0. 18985
104. High Pand N 5 p.m., April 24, 1918 cool... 25.08 7.59 39.90 12.08 0.22142

Tables VI—XII contain the results of the different determina-
tions. Table XIII gives the proportion of skeletal material in

1920]

WALSTER—BARLEY

11g

F,, calculated as the difference between the total amount of the

fraction, and the sum of the protein and starch in the fraction.

TABLE VII

EFFECT OF TEMPERATURE ON ACCUMULATION OF POLY-
$s

CCHARIDES IN BARLEY LEAVES

Culture no. and treatment Percentage of F; barn ct of
44. HighN het Foe Ns Sareea 21.16 8S 38
24. mh N Warn eS 21.64 12.63
4k High £ and N_ warm..... 20.43 11.63
208. « Tigh Ne C00k tives an .5Y 15.07
87. HighN oa Bh oe eee 23.60 14.99
104. High PandN cool.. 24.14 14.97
TABLE VIII

PHOSPHOPROTEIN PHOSPHORUS IN BARLEY LEAVE

PERCENTAGE

EFFECT OF TEMPERAT TURE ON AMOUNT OF NITROGEN, PHOSPHORUS, PROTEIN, AND

F TOTAL DRY WEIGHT)

Phospho-

Cult . and Total N Total P N i
ulture no. and treatment Perens i protein
44. HighN waym.......... 2.9779 6944 12.965 0.1167
24. HighN warm.......... 2.7007 0.6789 11.277 O.I411
41. High PandN warm 3.4661 0.7 14.425 0.0795
108. High N bs Bec cuits 2.5610 0.5479 12.865 0.0543
o7, Magn No cogl.. 2.606 0.5711 13.150 0.0832
104. High P an N cool... 2.5045 0.6532 2.008 ©.0996

TABLE IX

EFFECT OF TEMPERATURE ON AMOUNT AND DISTRIBUTION OF NITROGEN IN
BARLEY LEAVES

"

F; SOLUBLE IN ANHYDROUS |F2 SOLUBLE IN HOT ALCO! F; INSOLUBLE IN ALCOHOL,
ETHER AND WATER - ETHER, OR WATER
ULTURE NO. AND
spc ao. ois Percent- aga here Percent- Percent! “ol Percent- a var $
age age total|age to age age total| age age
fraction| leaf |N in leafjfraction| leaf |N in fraction| leaf Nin leaf
High N warm...... 4903 | 0.1304 | 4.38 | 2.3420 773 5.96 | 3.559 | 2.0743 | 69.66
High N warm...... 1.3081 | 0.1021 | 3.78 | 2.1312 | 0.7101 | 26.62 | 3.237 | 1 8795 ge
High P and N warm| 2.6700 | 0.2785 | 8.03 | 2.6970| 0.8705 | 25.377| 4.053 | 2.3081 -60
High N cool......, 4142 | 0.1167 | 4.55 | 1.2730 | 0.385 15.07 | 3.35% | 2.0584 | 80.38
High N cool... .... 1.2520 | 0.1084} 4.16 | 1.4110 | 0.392 15.00 | 3.315 | 2.10! 80.78
High P and N cool.) 1.3205 | 0.1014 | 3.01 | 1.4130 | 0.427 16.40 | 3. 2.0653 | 79.60

120 BOTANICAL GAZETTE [FEBRUARY

TABLE X

EFFECT OF TEMPERATURE ON AMOUNT AND DISTRIBUTION OF PHOSPHORUS IN BARLEY LEAVES
}

F, ee IN ANHYDROUS |F2 SOLUBLE IN HOT ALCOHOL!) F; INSOLUBLE IN ALCOHOL,
ETHER AND WATER ETHER, AND WATER

CULTURE NO. AND
TREATMENT Paseentt Percentd Percent Penoents Percent Percent Percent Percent-| Percent-
age age total et — age _|age total |age total age total ise bye
ion| leaf fractioi leaf | Pin leaf ition eaf
44. High No warn, 5% 0.7369 | 0.0641 9.23 | 0.8683 | 0.2866 | 41.28 | 0.5898 | 0.3437 | 49-49
24. N warm...... 0.6847 | 0.05390 7.93 | 0.8211 | 0.2770] 40.80] 0.5960 | 0.3478 | 51.27
41. High Pand N_ warm] 0.7857 | 0.0819 | 10.26 | 1.3304 | 0.4368 | 54.69 | 0.4918 | 0.2800 | 35.05
108. High N cool....... 0.7739 | 0.0638 | 11.65 | 0.5352 | 0.1622 | 29.62 | 0.5239 | 0.3218 | 58.73
87. High Cokes 0.7247 | 0.0627 | 10.99 | 0.50096 | 0.1417 24.80 | 0.5614 | 0.3565 | 64.21
104. High PandN _ cool..| 0.7975 | 0.0612 9.37 | 0.9602 | 0.2907 | 44.50] 0.4856 | 0.3012 | 146.13

TABLE XI
EFFECT OF TEMPERATURE UPON SOLUBILITY OF F; NITROGEN OF BARLEY LEAVES IN I PER
cENT NaOH (MATERIAL DIGESTED WITH I PER CENT NaOH ror
48 HOURS AT 37-40° C.)

SOLUBLE NITROGEN INSOLUBLE NITROGEN
CULTURE NO. AND TREATMENT

Percent: Percentage

P Percenta; Age lp P Ni

eroentnge [Perentage total N in |Peeptage /Petesntad® | otal Nin

“4. aN wart... 2.5... 0.910 | 0.5303 | 17.81 | 2.649 | 1.5440] 51.85
a4, HOON . War..; 3... 0.8570 | 0.4902 | 18.17 | 2.380 | 1.3892 | 51-43
41. HighPandN warm..... 1.126 | 0.6411 | 18.50 | 2.927 | 1.6670 | 48.10
$00. Eee oe : CODE coe 0.873 | 0.5361 | 20.93 | 2.478 | 1.5221 | 59-43
Sy; - High. N° cbel.. oe acc >| 2,052 | 0,6081 | 26.03 | 2.263 | .4373 | 54:75
104. High PandN cool...... 0.023 |-0:5726°| 22.07 |. 2.406 | %. 4096 | 57-53

TABLE XII

EFFECT OF TEMPERATURE UPON SOLUBILITY OF F; PHOSPHORUS OF BARLEY LEAVES
IN I PER CENT NaOH (MATERIAL DIGESTED WITH I PER CENT Na
FOR 48 HOURS AT 37-40°C.)

SOLUBLE PHOSPHORUS

(BY DIFFERENCE) INSOLUBLE PHOSPHORUS

CULTURE NO. AND TREATMENT . . ‘ee
P. Percentage] 4 “Tcentage| p, P el soil PG
eromguse Reese cou | penta) Porn| tal Pi
44. TGR N WAM. 6 oie: 0.2202 | 6.1335: | 19.22: 0.2102 | 30.27
24. High N vats Seyi Fk ar 0.19904 | 0.1163 | 17.13 | 0.3966 | 0.2315 | 34-10
41. HighNandP warm..... 0.1959 | 0.1115 | 13.96 | 0.2959*| 0.1685*| 21.09
108; High N obGh. co... pic: 0.1132 | 0.0696 | 12.70 | 0.4107 | 0.2522 | 46.03
Sy. High N- cook. <2 0.1807 | 0.1148 | 20.10 | 0.3807 | 0.2417 | 42-3
104. High NandP cool...... 0.1666 | 0.1039 | 15.91 | 0.3190f| 0.1979T| 30-39
* Poor duplicates. t One analysis only, duplicate lost.

1920] WALSTER—BARLEY 121

TABLE XIII
EFFECT OF TEMPERATURE UPON AMOUNT OF CELL WALL MATERIAL,
ETc. F;—[(N mn F;X6.25)+(sTARCH IN F;)]; EXPRESSED
AS PERCENTAGE OF TOTAL DRY WEIGHT OF LEAF

Ratio of supporting
Culture no. and treatment Cell Se rie e: oe .
: plant es ces,

including wa

44. High N i ee 32.99 0.0470

74. High N’ warm... 34.47 0.0525

4 High P and N warm. 30.90 0.0367

verage warm ...... 32.78 0.0454

108. High N Gea Gees ct 32.89 0.0530

$7. High N “cook... 35. 35.36 0.0581

104. High PandN cool... 34.16 0.0558

Average cool =... si 34.13 0.05590

TABLE XIV
EFFECT OF TEMPERATURE ON DISTRIBUTION OF PHOSPHORUS; SUMMARY TABLE
No. 24, HIGH N, WARM No. 87, HIGH N, CooL
MATERIAL
Percentage Percentage Percen Percentage
total | total P total } total P
this Ce wees 0.0539 7.904 °.0627 10.99
Phosphate P; Fi cies. 3: ©. 2105 31.01 0.0714 12.80
Rene fy eis vo ia Se 0.0665 9.80 0.0703 12.20
Phosphoprotein be O.I4II 20.80 0.0832 18.38
Nucleoprotein P, F, eo) ©. 2067 30.45 0. 2833 49.62
WUE es a O.0787 ie eens O.5900 ty. a.
Results of chemical analysis

LIPIN FRACTION (F,).—The results given in table V indicate
that the temperature has very little effect upon the amount of
lipins, except in the case of a high phosphorus supply, where the
percentage of lipins is decidedly higher. This fact is possibly
correlated with the higher percentage of phospho-lipin phosphorus
in the entire leaf, as shown in the third column of table X, and the
higher percentage of lipin N as shown in the third column of table
TX. Since the proportion of lipin P is practically the same for
both temperatures in the case of the high nitrogen series, these
data lead to the conclusion that the lipin fraction is not an impor-
tant growth determinant. The writer recognizes the desirability
of more data.

122 BOTANICAL GAZETTE [FEBRUARY

ALCOHOL-WATER SOLUBLE FRACTION (F,).—Table V shows a
distinctly higher average percentage of these extractives at the
higher temperature, although the order of difference is not large.
When, however, the composition of this fraction is examined cer-
tain striking differences are noted. The high temperature leaves
contain a much lower percentage of both total and reducing sugars
(table VI) and a lower percentage of polysaccharides (table VII).
The high temperature leaves contain about twice as much nitrogen
(as determined by the unmodified
Arnold-Gunning process) as do the
low temperature leaves (table IX).
In other words, the amount of active
metabolic nitrogen, such as amino
acids, polypeptides, and simpler water
soluble proteins, is much higher at
the higher temperature. The amount
of nitric N is also higher at the higher
temperature, as was indicated when
the modified Arnold-Gunning process
was used. The results of the nitric
N determinations are not reported in
yi i this paper. The high temperature
leaves also contain nearly twice the

Fic. 16.—Influence of tem-
perature on maturation (photo. | Percentage of alcohol-water soluble

16): no. 12, phosphorus. Duplicate determina-

hed
‘é Led sit b-¢
normal” fertilization (warm tions on one set of samples (nos. 24
. 74, ‘‘normal”’ fertili-

fit fosel hase and 87) indicated that this difference

was very largely due to the much
higher percentage of inorganic phosphorus at the higher tempera-
ture. These results are appended, although it is recognized that
more data are needed before any sweeping generalizations can be
made. The Powick-Chapin method was used in this determi-
nation.

Tora P Inorcanic P
Percentage of Percentage of Percentage of Percentage of
fraction entire leaf fraction entire leaf
No. 24 0.8211 0.2770 0.6240 0.2105

No. 87 ©. 5006 0.1417 0.2567 0.0714

1920] WALSTER—BARLEY 123

FRACTION 3.—The higher amount of polysaccharides at the
lower temperatures has been noted. Table V shows that the
leaves grown at the lower temperature contain a distinctly higher
average percentage of this fraction, although the order of difference
is not large. Tables [IX and X show that there is no important

Fic. 17 Fic. 18

17-18.—Fig. 17, influence of heavy N and heavy K on maturation (photo-
use); no. 112, heavy

graphed May 16): no. 63, heavy N+ extra heavy P (warm house); no. 126, hea
papi heavy P (cool hace, contrast with nos. % and 125 (same treatment)
difference in the percentage of either N or P at the different tempera- |
tures. The amount of phosphoprotein phosphorus seems to run
somewhat lower at the lower temperature (table VIII).

In five out of six cases (cf. column 3, table XII, with column s,
table VII) the amount of phosphorus in the NaOH extract exceeded
the phosphorus precipitable from that extract by 1 per cent NaOH,
indicating that either some organic phosphorus compounds had

124 BOTANICAL GAZETTE [FEBRUARY

been dissolved by the NaOH but had not been hydrolyzed, or
that the magnesia mixture failed to give quantitative precipitations
of the PO, ions under the conditions of the experiment.

Table IX reports a study of the solubility of the F, nitrogen in
1 percentage NaOH. The results are inconclusive, but are reported
for the sake of completeness.

The calculations reported in table XIII are self-explanatory.
It will be noted that the average proportions of framework material
are considerably higher at the lower temperature. Microchemical
examination of median cross-sections of the leaves and of the culms
showed a greater degree of lignification of the xylem bundles at the
lower temperature, a fact of added significance. Lignification of
the vessels in the culm adds greatly to the strength of the stem.
Referring to the enormous differences in growth habit as shown in
the figures, we may conclude that the upright habit at the lower
temperature is due to: (1) a greater proportion of culm to leaf;
(2) a greater proportion of skeletal material in the leaf; (3) a greater
degree of lignification of conductive tissues in both leaf and culm.
These obvious anatomical facts, however, are but the expression
of a difference in metabolic equilibria, especially the a di
carbohydrate ratio.

Discussion

The experiments reported in this paper, as well as the results
of earlier investigators, reopen the question as to just what is meant
by an optimum germination temperature. The classical investi-
gations of HABERLANDT on germination temperature place the
optimum at the temperature which most quickly permits the
emergence of the radicle and plumule; in fact, practically all germi-
nation studies have been based upon this asthe optimum. These
optimum temperatures, at least for the cereals, are evidently too
high to insure a future normal development. The writer believes
that the course of development is to a large extent predetermined
at a very early stage in the development of the plant by the chemical
equilibria within the seedling, especially the nitrogen-carbohydrate
ratio. These equilibria within the plant, like chemical reactions
in vitro, are conditioned by the temperature and concentrations
of the reacting substances. It seems likely that a high temperature

1920] WALSTER—BARLEY 125

U

and a high nitrogen supply at an early stage in the development of
the barley plant so shifts the equilibrium toward excessive vege-
tation as to prevent the normal tendency toward reproduction.
Some other factor must be altered, therefore, as, for example, the
water supply, if such plants are to be thrown into reproduction.

An investigation of the nitrogen-carbohydrate ratio at a differ-
ent stage in the development of seeds and seedlings furnished with
varying concentrations of nitrogenous compounds will probably
throw considerable light upon these questions.

Conclusions

1. The excessive leaf production in the high temperature barley
is caused by the high concentration of nitrates in the nutrient
supplied.

2. Nitrate nitrogen in the nutrient begins to affect the subse-
quent course of development at high temperatures at the time of
germination, or at least at a very early stage in the development of
the plant. The tendency to excessive vegetation thus inaugurated
cannot be counteracted by the addition of phosphorus or potassium
salts,

3. The effect of the nutrient supply is reflected in the compo-
sition of the active organ, the leaf. The following equations rep-
resent the main facts revealed by chemical analysis of the leaf:

High heat supply+high nitrogen supply in nutrient solution =
high soluble nitrogen in leaf+-low soluble carbohydrate = excessive
vegetation and little culm formation.

Low heat supply+high nitrogen supply in nutrient solution =
low soluble nitrogen in leaf+high soluble sala dagen =normal
vegetation and normal culm formation.

The writer gratefully acknowledges his indebtedness to Professor
WIttrAm Crocker for helpful advice and criticisms; to Professor
F. C. Kocu for valuable advice and laboratory facilities; and to
the Department of Zodlogy of the University of Chicago for facilities
afforded in their greenhouses.

AGRICULTURAL COLLEGE
N.D.

126 BOTANICAL GAZETTE [FEBRUARY

LITERATURE CITED

1. ADERHOLD, R., Uber das Schieszen des eres Mitt. Kais. Biol. Anstalt
fiir Land- und Poritniciachats 2:%

2. APPEL, O., and GassnER, G., Der Schitdliché Einflusz zu héher Keimungs-
temperaturen auf die spaitere Entwickelung von Getreidepflanzen. Mitt.
Kais Biol. Anstalt fiir Land- und Forstwirtschaft 4:5 ff. 1907.

3- GASSNER, G., Beobachtungen und Versuche iiber den Anbau und die Ent-
wickelung von Getreidepflanzen in subtropischen Klima. Jahresb. Vereini-
gung fiir Angewandte Botanik 8:95-163. rgro.

4. GASSNER, G., and Grime, C., Beitriige zur Frage des Frosthiarte der Ge-
treidepflanzen. Ber. Deutsch. Bot. Gesells. 31: 507-516. 1913.

5. GuTzeiT, E., Versuche iiber das Schossen der Riiben und anderer Pflanzen.
Mitt. Kais. Biol. Anstalt fiir Land- und Forstwirtschaft 6:20 ff. 1908

6. HELLRIEGEL (quoted by GASssNER), Beitrige zu den naturwissenschaftl.
Grundlagen des Ackerbaues. Braunschweig. 1883 (p. 434).

7. Hutcueson, T. B., and Quantz, K. E., The effect of greenhouse tempera-
tures on the growth of small grains. Jour. Amer. Soc. Agronomy 9:17-2I.
pls. 2. fig. I. 1917

8. Kocu, F. C., Lecture and laboratory notes in tissue analysis (Course 37
given in Department of Physiological Chemistry at the University of
Chicago). 1918.

9. Matuews, A. P., Physiological chemistry. 2d ed. New York. 1916.

1o. CHAPIN, R.C., nad Powick, W. C., An improved method for the estima-
tion of oveanie phosphoric acid in certain tissues and food products.
Jour. Biol. Chem. 20:97-114. 1915.

PHYSIOLOGICAL STUDY OF MAPLE SEEDS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 260
H. A. JoneEsS
(WITH TWO FIGURES)

Introduction

The appearance of two taxonomic species within the same
genus is not always a criterion of similar physiological or ecological
behavior. The seeds of two closely related species, as those of
the sugar and river maples (Acer saccharum Marsh. and A. sac-
charinum L.), show a striking contrast in season of maturity,
reaction to external conditions, chemical composition, and in their
physiological behavior in general. The sugar maple matures its
seeds in the fall, and these must pass through a well defined period
of after-ripening before germination can take place. The storage
substances are mainly protein and fat, with a small amount. of
carbohydrate present. On the other hand, the river maple ripens
its seeds in the spring. The seeds germinate almost immediately
upon a moist substratum, but if allowed to desiccate for some time
under ordinary atmospheric conditions they soon lose their power
of germination. A very small percentage of fat and protein is
present, starch being the chief storage product.

It is a matter of common observation that many mature seeds
and spores soon lose their power to germinate when subjected for
varying periods to atmospheric desiccation. In a great many
tropical seeds death follows atmospheric drying. In our own
region the seeds of the willow and cottonwood are usually cited
as the classic examples of death due to desiccation shortly after
seed fall. The cottonwood gives low percentage of germination
and low seedling vigor after two weeks of desiccation in laboratory
air, while after three weeks seeds fail to germinate when placed in
the most favorable germinative conditions. Cottonwood seeds,
however, are in a high state of metabolic activity when first shed.
127] : [Botanical Gazette, vol. 69

128 BOTANICAL GAZETTE [FEBRUARY

At 30° C. on moist filter paper the fresh seeds will usually give too
per cent germination within 24 hours. The hypocotyls will attain
a length of 8-9 mm., and the cotyledons will be entirely spread.
SCHRODER (23) states that seeds of Caltha palustris failed to
germinate after 11 weeks of storage over sulphuric acid and after
20 weeks of storage in the ordinary atmosphere. DELAVAN (8),
working with the oaks and hickories, concludes that a cold even
temperature, although the atmosphere be moist, is better than warm
dry storage of seed. Seeds of Oxalis, elm, river maple, hornbeam,
birch, beech, chestnut, and probably many others have their
germinative power lowered or lost entirely by varying periods of
desiccation.

Heretofore no work has been done on seeds, sensitive to drying,
regarding the exact or approximate water content at the time of
death. Furthermore, it has never been demonstrated whether loss
of viability is due in part to temperature or entirely to desiccation
effects.

Investigation
RIVER MAPLE (Acer saccharinum L.)

In the Chicago region Acer saccharinum matures its seeds
the latter part of May or early in June, varying with the season.
At the time of fall the seeds contain approximately 58 per cent of
water, being almost fully imbibed. The seeds soon germinate if
they lodge upon a moist substratum, but if they are subjected to
desiccation there is an immediate reduction of the moisture
content, and their viability is lost long before an air-dry condition
is attained. The seeds of the river maple were chosen for this study
because they are large, making it possible to obtain material readily
in sufficient quantities for chemical analysis. The period of time
between maturing and loss of viability is of moderate duration,
permitting a study of internal changes accompanying desiccation;
also seeds are abundant and easily collected. In all cases where
reference is made to the maple fruit the seed plus the ovary wall
is taken into consideration. Seed refers to the embryo plus the
integuments. In all storage conditions the entire maple fruit was
used; this holds for both the river and sugar maple. The criterion

1920] JONES—MAPLE SEEDS 120

for the beginning of germination is the protrusion of the tip of the
hypocotyl through the integuments.

Water and temperature relations

Fruits were collected at time of shedding and stored at various
constant temperatures from o to 40°C. At 25°C. and above
fruits were stored in open wire baskets. At 20°C. and’ below
they were stored in loosely covered cans which contained a con-
siderable quantity of calcium oxide. The lime facilitated drying
at the lower temperatures, besides preventing the accumulation
of an excess carbon dioxide pressure about the seeds. By
August 26, 1918, all seeds desiccated at o-40° C. had lost their

TABLE I

LIFE DURATION OF SEEDS STORED AT
VARIOUS DRYING TEMPERATURES

Storage temperature Life duration*

35 ACs den peveswers 6 days
BO es oo ee 8
25) Nee ie 22
RO eee ele a eel a a ee 20
TO a 49
Cy bie: eee Q2

* At 25°C. the humidity of the nsider
oy higher, and drying Sowa alg vision ves at
oe G6. unting for increased life duration.

ability to germinate. In all cases seeds were considered to have
lost their viability when 80 per cent failed to germinate when
placed on moist filter paper at 30° C., all seeds having either germi-
nated or decayed. From o to 35°C. the seeds lost their viability
when the water content was reduced to 30-34 per cent. So far
as could be determined, the various temperatures from o to 35° C.
for desiccation do not appear to raise or lower the critical point
of water content. At 40° C. death does not seem to be due to
desiccation. Seeds turn black in a short time, killing apparently
being due to the destructive action of this high temperature.
One apparent effect of increasing temperatures (o-35° C.) is the
Shortening of the desiccation period, no change being evident in

130 BOTANICAL GAZETTE [FEBRUARY

the percentage of water at several temperatures at the time of loss
of viability.

Seeds have a high metabolic activity at time of fall. Where
viability and vigor are so closely allied with high water content,
it is logical to suppose that the initial vigor can be retained for
some time by holding the water percentage at the initial content,
and by lowering the metabolic activity. Seeds at maturity and
for some time thereafter give off considerable amounts of CO..
For a number of samples at time of fall the yield of CO, was esti-
mated as approximately 7 mg. per gram of dry weight per 24 hours
at 25°C. If we consider 7 mg. as the amount of CO, respired in
24 hours at 25° C., the seeds would soon exhaust their store of food
if the initial activity were maintained. The carbohydrate present
would be entirely exhausted and the seeds die of starvation within
approximately 120 days if this initial intense respiratory activity
were maintained. At this rate it would be impossible to hold seeds
just below the point of saturation at the higher temperature for
any great length of time. Seeds, however, can be held for some
time stored over water at low temperatures. Seeds harvested in
the spring of 1917 were stored over water in desiccators at 10° C.,
and continued to give 95-100 per cent germination until November
1917. There was, however, an abnormal development of the hypo-
cotyl during the latter part of the storage period at 10°C. No
alkali was placed in the desiccators to prevent CO, accumulation,
so it is impossible to say just what part was played by the carbon
dioxide in the preservation of the seeds at this temperature. In
the spring of 1918 seeds were stored over water in a large desiccator
ato° C. A bottle of strong alkali was also placed in the desiccator
to prevent accumulation of a CO, blanket. These seeds were
discarded after 102 days’ storage, and at this time seeds were
giving 100 per cent germination. They had retained their initial
vigor and appeared to be normal in every respect. Perhaps many
other seeds of this general behavior would retain their viability
and vigor for considerable periods when placed in similar storage
conditions. Seeds can be kept for a considerable period at tempera-
tures just below the freezing point. After 50 days seeds stored
at —5° C. gave good germination. At this low temperature care

1920] JONES—MAPLE SEEDS 131

must be taken that water does not come into contact with the outer
walls of the fruit or integuments, as ice formed on the latter appears
to inoculate the subcooled tissue below, and freezing to death results.

Respiration

Respiration was determined on newly collected seeds, on seeds
desiccated at 25° C., and on germinating seeds. Determinations
were made on the sedeoatiag seeds every second day until viability
was lost, and for several weeks thereafter. All respiration experi-
ments were conducted at 25° C., as this temperature was thought
to correspond very closely with the average temperature to which
the seeds would be subjected under natural conditions. The
method of determining the carbon dioxide given off was that
described by GRAFE (12), with slight modifications. In general
the method consists in pulling carbon dioxide free air over the
respiring material through a column of barium hydroxide. The
barium hydroxide solution is held by a Reiset tube. The air is
drawn through slowly and uniformly. This is accomplished best
by the air replacing water which is slowly siphoned out of a large
demijohn by means of a capillary tube. At the end of a determina-
tion the barium carbonate was allowed to settle and an aliquot
part (25 cc.) of the toocc. of barium hydroxide was pipetted off
and titrated with N/2o0 oxalic acid. Phenolphthalein was the
indicator used.

If the intensity of respiration may be used as a criterion of
metabolic activity, then the seeds of the river maple at time of
fall are in high state of metabolism. In the desiccating seeds there
is a fall the first few days in respiratory activity, and then a gradual
rise until a maximum is reached. This maximum is retained for
several days, then there is a gradual decline, until only a trace of
carbon Su. is given off. This secondary rise in respiratory
intensity may accompany increased starch hydrolysis. It will be
seen later that accompanying desiccation there is a great increase
in sucrose, due to starch hydrolysis. The later fall in respiratory
activity is probably caused by a deficiency of water. The greatest
respiratory activity was obtained on the desiccating seeds with a
water content of approximately 44 per cent. There is no marked

132 BOTANICAL GAZETTE [FEBRUARY

degeneration of the respiratory enzymes during this fall, because
when dead seeds are placed in germinative conditions the respira-
tion again mounts to a high value, giving off 8.84 mg. of carbon
dioxide per gram of dry weight in 24 hours. It is not known,
however, just what percentage of the carbon dioxide given off in
the latter case was due to bacterial action. Haas (13) found that
the marine alga Laminaria, in the presence of certain reagents,
respired more rapidly after death than in the living condition.
MaiceE and Nicotas (17) have done considerable work on respira-
tion in correlation with the state of turgidity of certain plant organs,

10

a ~

8 NAN a
: Re \

a Pd

4

3 TN

2

, J
013 5 79 19 15 7 19 21 23 25 27 29 31 33 35 37 39 41 43 45

Fic. 1.—Respiration curve for seeds desiccating at 25° C.; mg. of CO, given off
in 24 hours per gm. dry weight plotted on ordinates; time of desiccation in days
plotted on abscissae; great rise in respiration after forty-third day due to placing
desiccated seeds (dead at time) under favorable germinative conditions.

as buds, leaves, and embryos. They find in material taken directly
from the tree increased carbon dioxide production with increased
turgescence, also for decreased turgescence, and usually an increase
in respiration when decrease was followed by an increase. Fig. 1
represents the trend of respiration during 43 days of degftcation.
‘The sudden rise on the forty-fifth day shows respiratory activity
of seeds after being placed in germinative conditions.

To determine the respiratory activity of germinating seeds,
newly collected seeds were planted in the dark at 25°C. The
respirometer used was a 500 cc. graduated cylinder. This was halt
filled with shredded filter paper, previously well sterilized. The

1920] JONES—MAPLE SEEDS 133

filter paper was packed very loosely in the graduated cylinder. The
seeds were washed with distilled water and planted near the surface
of the paper, about midway between the top and bottom of the
chamber. A small amount of water was run into the respirometer.
The top was stoppered and supplied with an inlet tube which
extended to the bottom of the chamber and brought in the carbon
dioxide free air, and with an exit tube which carried the carbon
dioxide laden air to the Reiset tube. The seedlings were grown
in the dark and consequently there was no food manufactured.
Storage food only was used up in respiration.

The respiratory activity of the germinating seeds reaches a
maximum about the eighth day at this temperature. At this time
the seedling has elongated considerably, the radicle having attained
a length of 7-10 cm., varying considerably with the individual.
After the eighth day respiration decreases gradually. Seeds
stored for several weeks at a low temperature (0° C.) and then
transferred to a high temperature (25° C.) in germinative conditions
show a very high initial respiratory intensity, which soon drops
to normal, and then again increases. PALLADIN (20) found that
transferring the tips of etiolated bean seedlings from a lower to a
higher and also from a higher to a lower temperature increased the
Tespiratory activity. According to APPLEMAN (1), tubers stored
at low temperature for several weeks and then transferred to room
temperature respire more intensely than tubers of the same lot
not subjected to the cold storage conditions. He thinks this
increased respiration might result from the increased accumulation
of sugar at the lower temperatures.

Fig. 2 shows the march of respiration during the first 14 days
of germination in the dark. In general this curve agrees with that
found by RiscHawi (21) for the respiration of the wheat seedling
growing in the dark, but is quite different from that found for
the bean.

Catalase activity

The apparatus used for catalase determinations was a modified
form of the one used by APPLEMAN (2). Determinations were made
upon fresh seeds, seeds desiccating at 25° C., and also seeds germi-
nating in the dark at 25°C. Entire seeds were used in all cases.

134 BOTANICAL GAZETTE [FEBRUARY

Material was weighed, then ground in a mortar with a small amount
of quartz sand and a knife point of calcium carbonate for exactly
2 minutes. This emulsion was then washed with the aid of ro cc.
of distilled water into a 200 cc. wide-mouthed bottle. The latter
was then corked and plunged into a water bath kept at 25°C.
The commercial form of Oakland dioxygen was used at all times.
This dioxygen gives an acid reaction. To neutralize the acidity
a small excess of calcium carbonate is added to the dioxygen just

35 3 ae ipa

30 , a N

ers ag

tm 7

I. Siete 2 48. G7

8: 8..10 AN 2 Ree

Fic. 2.—Respiratory curve for first 14 days of germination in dark at 25° C.;
time of germination in days plotted on abscissae and mg. of CO: given off in 24 hours
per gm. of dry weight plotted on ordinates.

before using. If the acidity is not corrected, the catalase activity
is reduced approximately one-half. A small separatory funnel
inserted in the cork of the bottle holds the dioxygen. The latter
is run into the ground tissue when the dioxygen and pulp have
reached the same temperature as the water bath. The material
is then shaken uniformly for 10 minutes by means of a small motor.
The oxygen liberated is collected over water at atmospheric pres-
sure in a roocc. burette. Table II shows the catalase activity
at various times during desiccation and the early stages of
germination.

1920] JONES—MAPLE SEEDS 135

Catalase activity increases slightly during the first few days of
desiccation, but decreases gradually thereafter. This activity
seems to align itself in a general way with respiratory activity,
which remained high for a considerable time. With germination
the catalase activity increases enormously, appearing to be closely
correlated with metabolic activity. There is not a sudden drop in
the catalase activity at the time of loss of viability, as one might

TABLE II
CATALASE ACTIVITY tetnypmagecnione DESICCATION AND FIRST STAGES
¥ GERMINATION
No. oF Cc. OF O2 GIVEN OFF BY 1 GM.OF
DRY IN
CoNDITION OF SEEDS OF SEEDLINGS
5 minutes to minutes
Fresh seeds collected se! 2 {3 sda 052 1248
Des iccated at 2 5° C. for alas 1035 1373
24 3
cc “cc “c “ee 5 fe — pat!
ii9 “ce ee e io oe a! B48
ce “cc “cc “ I Piles ely 1022 12590
“ec “ “a pte nea 868 1098
" oe OC 731 979
“ a. ee 34 fe peor 688
+ ast ate uel evap 461 593
hie saga in laboratory for 8 gia 380 590
eedlings with radicle : cm. long... .. 1245 1565
gee 1717 2055
‘c “cc (t3 4 “cc $6 eae 2106 2566
“ “ce cc cc ag a 2 8
“ “ “ec E “ec age gn iCS, ae 4472

expect, but a gradual decrease correlated with respiratory activity
and water loss. After a storage for 8 months under laboratory
conditions the catalase activity was reduced more than one-half
below that of the fresh seed.

*

Oxidase and peroxidase

Peroxidase activity is very intense in the fresh seeds. A dark
blue color is obtained immediately upon addition of alcoholic
Solution of benzidine and a drop of dioxygen. As desiccation
progresses there is a gradual decrease in peroxidase activity. In
one-year-old dead seeds there is only a very pale blue color evident

136 : BOTANICAL GAZETTE [FEBRUARY

about the vascular tissue when this method is used. No oxidase
could be detected by the ordinary qualitative chromogenic methods.
in either the living or desiccated seeds.

Chemical analysis

In the following analysis seeds were collected from the same
tree in order to eliminate differences due to individual variation.
The collection was made in the spring of 1917. Fresh seeds were
immediately placed in g5 per cent redistilled alcohol, enough being
added to make the final volume of alcohol 80 per cent. One-half
gram of calcium carbonate was added to guard against possible
acid hydrolysis. In the final calculation the calcium carbonate
was considered as being in the insoluble fraction. In general the
method of extraction and analysis is that outlined by Kocu (16),
but a few modifications were found necessary.

TABLE III
Fraction Fresh seeds Desiccated seeds
Percentage F; of total dry weight .. 79.05 65.56
ce F, ce “ce oc “cc Se 15.8 ag..24
“e Fos ‘“ «cs 5.15 4.13

The tissue was ground, and then extracted with hot 95 per cent
alcohol for four hours, followed by 1-hour ether extraction. The
alcohol-ether insoluble material was then heated in water for
one hour on the steam bath. The water was evaporated down,
alcohol again added, and returned to extraction cups for a 24-hour
alcohol extraction and 1-hour ether extraction. The alcohol and
ether extracts were combined, evaporated to dryness, and then
extracted with anhydrous ether. This ether extract is known as
F,; the reSidue from the ether extract is F,; the alcohol-ether
insoluble material is F;. F,; was dried in the oven at 103° C. for
5 days, then cooled and weighed.

The 1917 seeds were desiccated in the laboratory. No attempt
was made to maintain a constant temperature. The seeds failed
to germinate after 18 days, when the water content had dropped
to approximately 34 per cent. The desiccated seeds were treated
in the same manner as the fresh seeds. Table III shows the

1920] JONES—MAPLE SEEDS 137

percentage variation in the various fractions accompanying des-
iccation.

It can readily be seen that accompanying desiccation under
laboratory conditions there is a great increase in F,. One would be
led to expect quite the contrary, as condensation is quite commonly
associated with desiccation in plants. Table IV shows more in
detail to what this increase is due.

During the period of desiccation there has been an enormous
increase in the percentage of sucrose. Accompanying this increase

TABLE IV
. ANALYSIS OF FRESH AND DESICCATED SEEDS
PERCENTAGE TOTAL DRY WEIGHT
MATERTAL :
Fresh seeds Desiccated seeds
Free reducing sugar. 65s cS yews O83 0.43
py bay (ealctdated as invert sugar) . 4.53 14.41
StAICR hi Sa 48.18 36142
F, Nitsoees Dots a 4haege ee ss es 0.03 0.02
Fy Naropa: 0.65 °.80
Fy Nitrogen y 2536 nc i ea ins 3.30 3.28
FP, Phiompnorys. 6500 os es 0.03 0.02
Fs Pioesnores oo, 0 ec 0.18 0.31
Fs PRON sooo aos peek 0.50 0.35

is a corresponding decrease in the starch content. Free reducing
sugars remain approximately the same. In the desiccated seeds
we also find a slight increase in phosphorus and nitrogen in F,.
The nitrogen here represents merely the Kjeldahl nitrogen.

SUGAR MAPLE (Acer saccharum Marsh.)
Historical

A very different type of behavior is found when the seeds of
the sugar maple are considered. Germination here is initiated by
a distinct period of after-ripening. Investigators generally have
used the term “‘after-ripening’’ as referring to the series of chemical
or physical changes occurring within the embryo or associated
structures, which bring to a close the dormant period and make
germination possible. The factors operating to cause delayed
germination in most types of seed dormancy studied to the present

.

138 BOTANICAL GAZETTE [FEBRUARY

time have been treated in some detail by CROCKER (5). Seeds
that have dormant periods fall naturally into two groups: (1) seeds,
like certain members of the Leguminosae, have embryos capable
of immediate germination, but dormancy is here induced by asso-
ciated structures like the seed coats or pericarp; (2) the embryo
itself may be the cause of delayed germination. The second type
of dormancy may be due either to an immature embryo, as found in
Ceratozamia (4) and Ilex opaca (14), the former often being shed
at the time of or shortly after fertilization, while in the holly the
embryo is merely a globular undifferentiated group of cells at the
time of seed fall; or dormancy may appear in apparently fully
matured embryos, as is the case in some members of the Rosaceae.
The seeds of the sugar maple fall into the latter group, having
a dormant, morphologically mature embryo.

Davis and Rose (7) found that in nature Crataegus mollis has
a dormant period of a year or more. This period of dormancy
can be shortened considerably by removing the carpel and testa.
It is doubtful whether any such interrelation exists between the
embryo of the sugar maple and its inclosing structures.

The sugar maple sheds its fruit in the fall, after the first few hard
frosts. When given the most favorable conditions for germination
at time of fall the seeds fail to respond. The seeds must be kept
at a low temperature, with plenty of moisture present for a consider-
able period of time for after-ripening to reach completion. Under
natural conditions, if the seeds are kept moist during the fall and
winter, after-ripening will be complete the latter part of February
or early part of March.

Investigation

The object of the investigation was twofold: (1) to determine
the optimum temperature and water relations for after-ripening;
and (2) to determine the changes taking place within the embryo
during the after-ripening period. The fruit of the sugar maple
was collected the latter part of September and early part of October
direct from the trees in the Chicago region and northern Indiana.
Fruits were stored dry in wire baskets at various temperatures
from — 5 to +30° C.; others were stored in desiccators over water at

1920} JONES—MAPLE SEEDS 139

5° C. and 10° C.; also, some were stored out of doors on the surface
of the ground ie kept covered nite the fall and winter to prevent
drying.
Temperature and water relations

When seeds were stored dry, in no case, regardless of storage
temperature, did after-ripening reach completion; that is, no dry
stored seeds would germinate when placed in Petri dishes on moist
cotton at favorable germination temperatures. All dry stored
seeds required a prolonged stay at low temperatures with plenty
of moisture present to completely after-ripen. Davis and Roser
found that after-ripening in the haw proceeded best at tempera-
tures near 5°C. The sugar maple was also found to after-ripen
best at about this temperature.

In January, after three and a half months of dry storage,
specimens were removed from each of the dry stored samples,
and placed at 5°C. under good germinative conditions. The
pericarp was removed and the seeds that had been dry stored
at 5° C. were the first to complete their period of after-ripening,
most of the seeds completing after-ripening during the fifth week.
The seeds, however, do not after-ripen uniformly; some precede
and others follow the general average time. Seeds dry stored
at —5°C. take the longest time to complete their period of after-
ripening, taking 4-5 weeks longer than seeds dry stored at 5° C.
Seeds dry stored at 1o-30° C. after-ripen more slowly than seeds
stored at 5° C., and more quickly than seeds stored at —5°C. In
“other words, seeds dry stored at 5° C. have progressed farthest,
and those stored at —5° C. have progressed least in the process
of after-ripening at their respective storage temperatures. The
factor limiting the complete after-ripening in the dry stored seeds
at low favorable temperatures is a deficient water supply. Only
in the presence of sufficient water can the various processes go
progressively on to complete after-ripening.

Fruits stored on the surface of the ground were subjected to
the temperature ranges of the soil surface. The seeds, however,
were kept saturated, due to the extremely wet fall and winter.
At time of fall seeds had a water content of 55 per cent, and during
the entire fall and winter the water content remained at 55-57 per

140 BOTANICAL GAZETTE [FEBRUARY

cent. Inthe seeds stored out of doors and in desiccators over water
there was no indication of increased water holding capacity accom-
panying after-ripening. Seeds stored in desiccators at low tempera-
tures over water are completely after-ripened several weeks before
seeds stored out of doors. Table V shows how after-ripening
progressed in seeds stored out of doors. As after-ripening pro-
gressed, less and less time was required for the completion of this
process when placed in the germinator at 10° C.

’ TABLE V

Percentage of germination after number of days indicated

Put to germinate at 10° C.
: 2 3 4 5 6 8 12 17 26 30] 35

January 16, 1918...... sot 68 | 88
PODIUAIY 4,-3.4 Soe eel of os seis ae Od ea oe

February 28200500... 05 a0 ho eo eS Ss Ue ete ones
PARLOR ae AO: OF 87 BS 1 Ok OF Od od oars eo oer ees

Seeds after-ripened out of doors and at 5° C. are more vigorous
than seeds after-ripened at slightly higher temperatures (10° C.).
Dry stored seeds at low temperatures are more vigorous when
after-ripened than seeds previously dry stored at high tempera-
tures. This question of vigor should be given more attention than
it has been given up to the present time. There is something very
significant in the fact that maximum vigor can be obtained by
after-ripening seeds at a temperature so much below the optimum
germination temperature and at a temperature which we consider
retarding to metabolic activity in general. Poor germination and
high seedling mortality can be replaced by good germination and
vigorous seedlings when the most favorable temperature (about
5° C.) and water relations are used for after-ripening. After-
ripening and germination is a continuous process, but the
optimum temperature for germination is considerably above the
optimum for after-ripening. Seeds completely after-ripened at
5° C. are stimulated to very rapid growth when placed at higher
temperatures. On the other hand, if seeds are completely after-
ripened and then allowed to desiccate at higher temperatures,
seedling vigor is lowered as time progresses, and in several weeks the

1920] JONES—MAPLE SEEDS 141

embryo fails to respond when placed in favorable germinative con-
ditions.. The reason for this loss of vigor is not known. It may
be due to the increased respiration, using up the plastic substances
essential for the initiation of germination, or to the introduction
of some new factor inhibitory to growth. After-ripened seeds
placed at —5° C. and kept saturated by packing in snow will retain
their initial vigor for a considerable time.

Oxygen pressure

The most favorable oxygen pressure for after-ripening was not
studied in detail. Seeds after-ripened in desiccators are under
considerably reduced oxygen pressure. The oxygen is soon used
up in respiration. Nevertheless, these seeds stored at a low
constant temperature will after-ripen quicker than seeds stored out
of doors with a good supply of oxygen, but subjected to fluctuating
temperatures. Seeds stored in open baskets, but kept saturated
at low constant temperatures, will after-ripen sooner than those
stored in desiccators, and the resulting seedlings appear to be more
vigorous.

Oxidase and peroxidase

EcKERSON (11) found an increase in oxidase and peroxidase
activity accompanying after-ripening in the haw. In the peach
CROCKER and HARRINGTON (6) found no increase in oxidase activity
in the after-ripening seeds when ordinary chromogens or the Bunzel
methods were used, but the pulp of the after-ripened seeds exposed
to air shows a more rapid oxidation of its own chromogens. In the
Sugar maple there is a slight increase in peroxidase activity accom-
panying after-ripening, being more pronounced in the hypocotyl.

No oxidase could be detected in dormant or after-ripened seeds |

when guaiaconic acid or benzidine was used as a chromogen.

Catalase

One of the most consistent phenomena accompanying the
aiter-ripening of this type of embryo is the increase in catalase
activity. This increase is continuous, increasing manyfold during
the early stages of germination. EckEerson (11) found that
Catalase activity increased in the haw with after-ripening. In

/

142 BOTANICAL GAZETTE [FEBRUARY

Tilia ROSE (22) also found a noticeable increase in catalase activity
accompanying after-ripening. CROCKER and HARRINGTON con-
clude that “seeds that after-ripen in a germinator at low tempera-
tures (commercial layering), in which the dormancy of the embryo
is self imposed and the embryo experiences fundamental time-
requiring changes for after-ripening, show a great increase in
catalase activity with after-ripening (Crataegus, Tilia, Prunus).”,

Catalase determinations were made upon the dormant and
after-ripened seeds and upon the seedlings at various stages of
germination. In all cases the integuments were removed and a
definite number rather than a definite weight of seeds was used.
The material was weighed and samples were run as described for
the soft maple. The after-ripened seeds and also the seedlings
used were after-ripened and germinated in the dark at 10°C.
Table VI demonstrates the great increase in catalase activity
accompanying after-ripening and germination in seeds of the sugar
maple.

TABLE VI
cc. oF O. LIBERATED BY 1 SEED OR geared canes
STAGE WEIGHT
5 minutes ro minutes ro minutes
Dormant... oo eo os 23.4 ai\2 754
Fo cee ‘acag ME Ce ee 43:9 30.3 1117
Seedlings with rcm. radicle. . 31.0 37.0 1058
s 2 a Si.6 60.4 £7708
i. 3 : eat 87.2 98.4 2235
te ves or 09-7 I1I4.0 2230
. ga ie sd 89.2 107.0 2786
* oe ace 3 1¥5.3 130.0 4481
“ “ 7 “ “ 125.0 142.5 4440

An increase in catalase activity is evident in both cotyledons
and hypocotyl. Seeds germinated at higher temperatures also
gave slightly increased catalase activity when taken at the same
stage of development. Seedlings with radicles 1 cm. long were
used ‘to determine the relative catalase activity of the different
parts. One-tenth gram (wet weight) of radicles, cotyledons, and
integuments liberated in 10 minutes 95, 43, and 5.1 cc. of oxygen
respectively. The hypocotyl, which is the most actively growing

1920] JONES—MAPLE SEEDS 143

organ at this time, gives by far the greatest catalase activity.
The storage organs (cotyledons) give considerable catalase activ-
ity. The inert structures (integuments) give very low catalase
activity. The difference here would be still more striking if calcu-
lated as percentage of dry weight. Crocker and HARRINGTON find
the catalase activity of wheat embryo 28-29 times that of the en-
dosperm. The same investigators find that in grass seeds in general
the physiologically inactive organs show only a small fraction of
the catalase activity shown by the embryo.

Dry dormant seeds stored in the i Rae ie were used to
determine the Q,. for catalase activity at temperatures ranging
from 10°C. to 50°C. Seeds were ground very fine and rubbed
through a too-mesh sieve. One-tenth gram samples were used
for determinations. Ten cc. of dioxygen, 1occ. of water, and a
small excess of CaCO, were added to the meal. Table VII shows
the Q,. value for catalase activity.

TABLE VII
Qi FOR
TEMPERATURE
I minute 5 minutes to minutes
capt ik, Se apa pea ede Tees CU 1.4 +3 iis
WS ES ee koe a ss <.4 1.2 tt
WP a ees. o.1 0.9 °.8
Were oe ee 0.8 0.6 0.5

In no case does the van’t Hoff law, which calls for an increase
of 2-3-fold for every 10° C. rise in temperature, hold. The time
consumed in heating the sample to the higher temperature intro-
duces considerable error. The time required for complete destruc-
tion of catalase activity at any given temperature was not deter-
mined. There was still some catalase activity at temperatures
slightly above 50°C. AppLEMAN (2) found the catalase activity
in potato tubers to be entirely destroyed at 50°-C. Between c° C.
and 10° C. he finds the Q,. for catalase activity to be 1.5. From

0° C. to 4o° C. he gets lower Qyo values for potato catalase than
was given by the catalase of the sugar maple.

144 BOTANICAL GAZETTE [FEBRUARY

Chemical analysis

Samples were analyzed as in river maple, with slight modifica-
tions to suit the material. One-tenth gram of CaCO, was added
to samples at the time of collection. Figures in the tables represent
averages from several samples. Dormant seeds had made no
progress in after-ripening. It is almost impossible to choose seeds
for the after-ripened samples that are known to be completely
after-ripened. The only criterion for completion of after-ripening
is germination. The seeds in the after-ripened samples vary
from completely after-ripened ones to seeds probably within a
week or 10 days of complete after-ripening.

TABLE VIII
SUGAR CALCULATED AS PERCENTAGE TO TOTAL DRY WEIGHT
STAGE . ee
- 5 ¥ i
Free reducing sugar] (ag SUT ean) | PavSagcbaide
SOTMANE es 0.06 6.40 S23
Aitensivene OO ret eis 0.67 4.32 4.66
——— — radicles
about TCM... 5 coer 1.81 2.36 3-43
Seedlings with <3 cm. radicle
(with integuments)......... 444 1.80 5.91
Seedlings with rer cm. radicles
fitecunins SOG oe 0.06 2.62 5-43

The protein content of the seeds is exceptionally high. The
seeds contain 7.17 per cent of nitrogen or approximately 44.8 per
cent protein, calculated on a dry weight basis. The embryo itself
contains almost so per cent of protein. The nitrogen multiplied
by the factor 6.25 was used to indicate the amount of protein
present. The seeds contain about 17 per cent of ether extract
and 11.5 per cent of total sugars. The ash percentage is relatively
high, 5.87 per cent of dry weight, while o.91 per cent of the total
dry weight is phosphorus. Only a trace of free reducing sugar is
present in the dormant seeds, but sucrose or sucrose-like sugars are
present in considerable amounts. Table VIII shows the relative
amounts of various sugars at time of dormancy, approximately
complete after-ripening, and early stages of germination.

1920] JONES—MAPLE SEEDS 145

Accompanying after-ripening there is a considerable increase
in free reducing sugars. Free reducing sugar reaches a maximum
at the beginning of germination, and then diminishes as germina-
tion progresses. There is, no doubt, a considerable amount of
sugar used up in respiration during the long after-ripening period
in the germinator even at temperatures as low as 5° C. Whether
the appearance of considerable amounts of free reducing sugars is
merely correlated with after-ripening or is essential for the com-
pletion of after-ripening is not known. The formation of free
sugars may be favored by cool uniform temperatures and high
state of hydration of the embryo.

TABLE IX
Kjeldahl nitrogen as percentage of total dry weight in
Stage
F; F, F;
MMA Ss oes tice 0.03 1.58 5.56
Micexiver CO ees Fa eee 0.03 1.48 5-59
Be are oe radicle
ROOUE 2 Ci ee 0.03 04 5.29
Seedlings vith 2-3cm. radicle
eke integument ieee ews 0.03 2.37 4-73
with 5-6 cm. radicle)
pie catkio shed) paid 44 ? a 15 4.94

Seedlings with radicles 2-3 cm. long show an increase in poly-
saccharides, but a decrease in free reducing and sucrose or sucrose-
like sugars. Correlated with this increase in polysaccharides is a
considerable reduction in percentage of fat. The percentage of
ether extract drops from about 17 per cent in the dormant and
after-ripened seeds to slightly less than 14 per cent in the seedling —
with a radicle 2-3 cm. long. The fats in the early stages of germina-
tion are probably converted into sugar or sugar-like materials, as
found in the haw by Ecxkerrson (11), in the sunflower by
MILLER (19), and in the castor bean by DELEANO (9).

With germination there is the usual increase of the more
soluble nitrogen of F;. There is no significant change in relative
nitrogen value of the dormant and after-ripened seeds. Table IX
shows the relative amounts of nitrogen in the various fractions
at different stages of the seeds and seedlings.

146 _ BOTANICAL GAZETTE [FEBRUARY

Respiration
A detailed study of respiration of the after-ripening seeds at
the lower temperatures may help to interpret the metabolic activity
accompanying after-ripening. Little work has been done on this
phase up to the present time. Preliminary tests show very little
respiration taking place in dormant air-dry seeds. When these
seeds are soaked for 48 hours, however, and then transferred to the
respirometer, the respiratory intensity jumps to approximately the
same level as that of fully after-ripened seeds. Sufficient data
have not been obtained to justify a full discussion of the correlation

between after-ripening and respiration.

Hydrogen ion concentration

_ The gas chain method described by MiIcHAELIs (18) was used
to determine the hydrogen ion concentration. Two embryos
were used in each case. They were ground for 2 minutes with a
small amount of pure quartz sand and 1 cc. of distilled water, and
5 cc. of distilled water was then added. This solution becomes
more alkaline the longer it stands, so several readings were taken
immediately and the average of these used. In both the dormant
and after-ripened embryo we find a distinctly basic condition.
The average of several samples shows a Py value of 8.335 in the
dormant seeds and a P, value of 7.909 in the after-ripened seeds.
Both are distinctly on the basic side of the neutral point. The

hypocotyls of the dormant seeds gave a Py value of 9.048, while
_ that of the germinating seedlings with a 1 cm. hypocotyl gave a
P, value of 9.055. Seeds that had just started to germinate were
used in the latter case, to be sure that the period of after-ripening
had been completed. Eckrrson (11) found increased acidity in
the hypocotyl of the haw with after-ripening. In working with
Tilia americana ROsE (22) found increased hydrogen ion concentra-
tion with after-ripening. In the sugar maple the embryo is always
basic, although the hydrogen ion may increase in concentration in
the embryo when it after-ripens.

Discussion
To the present time little work has been done upon séeds that
show in general the same type of behavior as found in the river

1920] JONES—MAPLE SEEDS 147

maple. Numerous observers have reported cases of seeds dying
when subjected to atmospheric conditions for a short period of
time. As to just what factors operate with desiccation to cause
lowering of seedling vigor and early death we are still entirely
ignorant. In the river maple temperature does not appear to
determine the critical percentage of water loss. Death occurs at
all ordinary temperatures (o-35° C.) when the percentage of water
in the seeds has reached 30-34 per cent. Whether or not this will
hold in general for other seeds of this type will not be known until
considerably more species have been studied. In the desiccated
seeds we find a noticeable increase in permeability, indicated by
a large amount of sugar appearing in the substratum when placed
in the germinator. The sugar makes an excellent medium for
growth of bacteria and fungi, and in a.few days the entire seed is
completely decomposed. The fungi appear to be unable to attack
potentially vigorous seeds. Whether increased permeability is
the cause or the result of death is not known. Desiccation may
coagulate or denature the protoplasmic proteins, increasing per-
meability and subsequent leaching, allowing an inroad for parasitic
_ Organisms. This type of seed stands in marked contrast to that
type of seed which retains its viability best when stored in an
air-dry condition. Duvet (10) even recommends drying the
majority of seeds in a vacuum or over sulphuric acid to insure
good preservation. In fact, many seeds can be dried to constant
weight without lowering viability or seedling vigor. Kipp (15)
States: “In the case of certain rapidly deteriorating seeds (Hevea
brasiliensis) the.carbon dioxide naturally produced by respiration
of the seeds in a closed flask rose to 40 per cent, and the pressure
of this was found to be accompanied by a marked prolongation of
Vitality in the seeds. This prolonged vitality was far in excess of
that reached with the present commercial method of packing these
short-lived seeds for export.’”? Where there is a rapid oxidation
of food material due to high respiration, there is no doubt that
narcotizing the embryo would result in greatly reduced metabolic
activity. Whether or not high embryo vigor can be maintained in
the river maple by narcotizing still remains to be determined.
Storage at o° C. over water, however, provides an excellent con- -
dition for the seeds of river maple.

148 BOTANICAL GAZETTE [FEBRUARY

Recent studies have thrown considerable light upon the behavior
of seeds that require a definite time under certain favorable condi-
tions to after-ripen a morphologically mature embryo. The major
portion of the work up to the present time has been done upon
various members of the Roseceae. No doubt seeds of this general
behavior exist in many more of our plant families, especially among
the uncultivated forms. Not until more work has been done upon
a wider range of plants will it be known just how widespread this
phenomenon is. The few species studied thus far by various
investigators show remarkable similarity of behavior in several
features accompanying after-ripening. There are five more or
less specific changes, according to CROCKER and HarrINGTON (6),
which are quite conspicuous in the constant way which they seem
to accompany after-ripening in seeds of this type: (1) rise in vigor
of seedling, (2) increase in amount of water absorbed, (3) increase .
in total acidity, (4) increase in catalase, and (5) oxidase activity.

When after-ripening is accomplished under the most favorable
conditions of oxygen pressure, water relations, and temperature,
seedling vigor is in all cases at its maximum. In the sugar maple,
at least, seedling vigor can be judged only during the first stages
of germination after the completion of the period of after-ripening.
After-ripening, however, may complete itself under conditions not
favorable for the greatest expression of seedling vigor.

RosE found slight increase in acidity accompanying after-
ripening in the seeds of Tilia. This was correlated with greater
water holding capacity. In the haw (11) delayed germination of
the embryo has been found to be due to a dormant hypocotyl.
In the dormant seed this organ is slightly alkaline or neutral, but ©
' with after-ripening the hypocotyl becomes distinctly acid. Accom-
panying this increased acidity there is increased water holding
capacity of the hypocotyl, along with increased activity of the
enzymes. Here the hydrophilous colloids have a greater water
holding capacity in a slightly acid medium. When the entire seed
of the haw is considered, however, we find a slightly higher water
holding capacity in the dormant than in the after-ripened seed.
In the sugar maple the water holding power of the hypocotyl only
was not determined. Considering the hydrogen ion concentration

1920] JONES—MAPLE SEEDS 149

\
found in the hypocotyl of the dormant and ajfter-ripened seeds,
one would hardly expect to find a change in the water holding capa-
city of the hydrophilous colloids. Determinations on the water
content of entire seeds stored in favorable after-ripening conditions
show that there is no change in the water holding capacity of the
seeds as a whole.

One of the most consistent phenomena accompanying after-
ripening in this type of embryo is the great increase of catalase
activity. This appears to be an accompanying feature of more
than ordinary importance. A large number of investigators
in various branches. of animal and plant physiology attempt to
correlate catalase activity with metabolic activity in general.
BuRGE (3), by increasing the work of certain fowl muscles and,
consequently the respiratory and metabolic activity, has made

e catalase activity increase enormously. In the castor bean
DELEANO (g) found a rapid increase in catalase activity at the
beginning of germination. A great increase in catalase activity
accompanied germination in the sugar and river maples. In the
fully imbibed seed of Johnson grass, CROCKER and HARRINGTON
(6) found catalase activity paralleling respiration. This did not hold
for seeds of the amaranth, however. In the potato, APPLEMAN (1)
found respiratory and catalase activity closely accompanying each
other. Eckrrson (11) found an increase in the catalase activity
with after-ripening in the haw. An increase in catalase activity
with after-ripening has also been reported for Tilia americana (22).
In the sugar maple there was a 66 per cent catalase activity increase
in the after-ripened seeds over that of the dormant seeds. Just how
closely catalase activity and respiration parallel each other during
the course of after-ripening has not yet been determined. From
evidence at hand showing the almost universal correlation of these
two phenomena we might reasonably expect to find respiration
increase noticeably during the process of after-ripening. Respira-
tory activity should be determined continually throughout the
entire period of after-ripening at the temperature and water rela-
tions most favorable for after-ripening. Preliminary respiratory
determinations reported in this paper are not conclusive. The
seeds were transferred from 5° C. to the 20° C. oven. This change

150 BOTANICAL GAZETTE [FEBRUARY

in temperature no doubt introduces changes which may possibly
mask the real condition at the lower temperature.

Accompanying after-ripening in the sugar maple is an increase
in the amount of free reducing sugars. Just how generally this
occurs in this type of embryo is still unknown. Whether increase
in amount of free reducing sugar is essential for the completion
of after-ripening is problematical. Dormancy is probably due
to a temporary suppression in the development of one factor or a
group of factors essential for the normal functioning of the embryo
in germination. It is impossible to select any one factor as the
cause of dormancy in the embryo of the sugar maple at the present
time. Whether any certain observed change in the embryo accom-
panying after-ripening is responsible for bringing dormancy to a
close, or whether this change results merely from the conditions
to which the embryo has been subjected, remains a question.

Summary
RIVER MAPLE

1. Seeds lose théir viability when the water content is reduced .

to 30-34 per cent.

2. Temperature seems to play no part in determining the critical
point of water loss. Higher temperatures only hasten the rate
at which the point of desiccation is attained.

_ 3. Respiratory activity in the desiccating seeds at 25° C. first
decreases slightly, then rises to a maximum, then gradually falls
to zero as desiccation progresses.

4. After a slight initial increase, catalase activity gradually
decreases in the desiccating seeds. Catalase activity increases
enormously during the early stages of germination.

5. Seeds of a river maple may be kept in a vigorous viable

condition for a considerable period of time at low temperatures .

(o° C.) stored over water.
6. There is a gradual decrease in peroxidase activity accom-
panying desiccation.
SUGAR MAPLE
1. Seeds after-ripen best at temperatures near 5° C., with a
good supply of oxygen and moisture.

1920] JONES—MAPLE SEEDS I5i

2. With after-ripening the seeds show a considerable increase
in free reducing sugars.

3. Catalase activity increases greatly with after-ripening and
germination; there is also a slight increase in peroxidase activity.

4. Both the dormant and after-ripened seeds have a reaction
that is distinctly alkaline; this holds for the hypocotyl as well as
for the entire embryo.

5. Fully after-ripened seeds will remain in this condition for
a long time if kept moist at — = 2

Acknowledgments are due Dr. Crocker and Dr. EcKERson,
through whose efforts and encouragement this piece of work was
made possible. Many thanks are due also to Dr. T. G. PHILLIPs,
who very kindly made the hydrogen ion determinations.

WEST VirciniA STATE AGRICULTURAL EXPERIMENT STATION
Morcantown, W.VA

LITERATURE CITED

1. APPLEMAN, Cuas. O., Relation of catalase and oxidases to respiration’ in
plants. Md. Agric. Exper. Sta., Bull. 191. 1-16. 1915.
2. , Some observations on catalase. Bort. GAZ. 50:182-192. Igto.
_ 3. Burce, W. E., Comparison of catalase content of the breast muscle of
wild pigeons and of bantam chickens. Science 46:440. 1917.
4. CHAMBERLAIN, C. J., Preliminary note on Ceratozamia. Bort. GAZ. 43:137.

1907.

5. CROCKER, Wm., Mechanics of dormancy in seeds. Amer. Jour. Bot.
3299-120. 1916.

6. CROCKER, W., and Hisieeoros. G. T., Catalase and oxidase content
of seeds in jelatioti to their dormancy, age, vitality, and respiration.
Jour., Agric. Res. 15:137-174. 1918.

‘7. Davis, W. E., and Ross, R. C., The effect of external conditions upon the
after-ripening of the seeds of Crataegus mollis. Bot. GAZ. 54:49-62. 1912.

8. DEtavan, C. C., The relation of the storage of the seeds of some of the
oaks and hickories to their germination. 17th Ann. Report, Mich. Acad.
Sci. 161-163. 1916.

9. DELEANO, N. T., Recherches chimiques sur la germination. Centralbl.
Bakt. und Par. 24?:130-146. 1909.

to. Duvet, J. W. T., The vitality and germination of seeds. U.S. Bur. PI.
Ind., Bull. 58: ae 1904.

152 BOTANICAL GAZETTE [FEBRUARY

11. ECKERSON, Soputa, A physiological and chemical study of after-ripening.
Bor. Gaz. 55:286-299. 10913.

12. GRAFE, VIKTOR, Ernahrungsphysiologisches Praktikum héherer Pflanzen.
Berlin. 1914 (p. 99).

13. Haas, A. R. Ms Rapid respiration after death. Proc. Nat. Acad. Sci.

3:688—690

14. ives, S. ‘is Vovablished work at Hull Botanical Laborato

15. Kipp, FRANKLIN, The controlling influence of carbon dioxide in the
maturation, —s and germination of seeds. Proc. Roy. Soc.

87:408-421. I9
16. Kocu, W., Methods for the Seagate chemical analysis of animal
tissues. Jour. Amer. Chem. . 3131329-13

364. 1900.

17. MalIcE, A., and Nicoras, G., achethes sur l’influence des variations de
la turgescence sur la respiration de la cellule. Rev. Gen. Bot. 22:409-422.
1g10; rev. Bot. GAZ. 51:314. IQII

18, MicHaEtis, Leonor, Die Wasserstoffionenkonzentration. Berlin. 1914.

19. Mitter, E. C., A physiological study of the germination of Helianthus
annuus. Ann. Botany 24:693-726. 1910.

20. Pattapin, V. I., Plant physiology. Eng. ed. by Livingston. Phila-
delphia. 1917.

21. RiscHawt, L., Einige Versuche iiber die Athmung der Pflanzen. Landw.
Vers. Stat. 19:321-340. 1876.

22. Ross, R. C., After-ripening and ares of seeds of Tilia, Sambucus,

23. Scuréper, G., Uber die pistiec taligahovait des Pflanzen. Untersuch.
Bot. Inst. Tiibingen 2:1-52. 1886,

POLYEMBRYONY AMONG ABIETINEAE
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 261
Joun T. BucHHOLZ
(wire FIFTEEN FIGURES)

Re arte among conifers is of two kinds: cleavage poly-
embryony, in which a single fertilized egg gives rise to many
embryos; and the simple polyembryony, which is due to plurality
of archegonia. This latter form is encountered wherever there are
several eggs that may be fertilized, and therefore is found among
all gymnosperms. The fact that polyembryony was found in both
the pines and the cycads, and was due to plurality of “corpuscula”
or “areolae”’ (archegonia) in both instances, was one of the argu-
ments presented by BRown (1, 2) as early as 1826 as showing a
fundamental relationship between these two groups.

A form like Pinus, which has cleavage polyembryony, usually
has several eggs fertilized also, and therefore combines both forms
of polyembryony. Since each zygote in Pinus usually gives rise
to a system of 8 embryos, there may be as many embryos as 8 times
the number of fertilized eggs. If all 6 of the archegonia of some
species were fertilized, 48 embryos might be produced, but 4 is the
maximum number of embryo systems that have actually been found,
and even then many of the embryos disappear very early, some of
the rosette embryos being aborted without division of the embryo
initial cell.

In discussing polyembryony, it is necessary to consider briefly
the pine proembryo stages, shown in the accompanying figures.
The writer’s interpretation of the facts brought out by various
investigators, together with his own studies, would describe the
initial steps in the development of the pine embryo as follows.

The zygote begins development with free nuclear divisions
(figs. 1-3). When 4 free nuclei have been formed they.descend to
the bottom of the egg, and there undergo another free nuclear divi-
sion, after which the primary embryo initial group of cells () is
153] é [Botanical Gazette, vol. 69

154 BOTANICAL GAZETTE [FEBRUARY

cut off by complete walls from the rest of the cytoplasm of the egg.
Each cell of this tier constitutes an initial cell to one of the 4 primary
embryos. The tier above it is not completely walled, and therefore
undergoes another free nuclear division, organizing the second tier of
completely walled cells (r), the rosette tier, a group of initial cells
of the rosette embryos. The open tier of free nuclei (0) which
remain above this undergo no further division and soon disintegrate.
When these 3 tiers of 8 walled cells and 4 free nuclei have formed,
as in fig. 5, the organization stage of the proembryo is concluded,
for each cell is now ready to produce its own distinct embryo,
although the 4 cells of the primary embryo initial tier (p) continue
their further development in unison.

Fics. 1-5.—Steps in development of proembryo in Pinus, diagrammatic recon-
structions from serial sections and published figures: #, tier of primary embryo initial
cells; 7, tier of rosette cells, initial cells of rosette embryos; 0, upper open tier of cells;
normally tiers ry and o come from division (free nuclear) of upper tier of fig. 4

From each of these 8 completely walled embryo initials (fig. 5)
an embryo develops by means of an apical cell, this cell functioning
first as a hemispherical apical cell of one cutting face, and later as
a semi-pyramidal cell of 3 cutting faces, in a manner described
in greater detail elsewhere (3). It may be added that this apical
cell persists until an embryo mass of about 500 cells has been
formed, after which it is replaced by the meristematic group of
cells found in the older conifer stem tip. This apical cell is a primi-
tive feature in which conifers recapitulate their fern phylogeny.

THE EARLY EMBRYO OF Pinus.—The cells (~) of the embryo
initial undergo simultaneous division, in which their first apical

1920] BUCHHOLZ—POLYEMBRYONY 155

cell segments (s), the primary suspensor cells, are cut off. This
group constitutes what has generally been recognized as the sus-
pensor tier of the 16-celled stage (cf. figs. 5, 6). Next- the sus-
pensor cells (s) elongate and thrust the embryonal tier of apical
cells into the pocket which the digestive enzymes of the eggs and
embryos have corroded within the
gametophyte, the 4 embryo units
separating and their apical cells
(a) continuing to give rise to segments
(€:, €2, etc.), which elongate and add
to the suspensor.

Soon the rosette group of initials
divides and the development of the
rosette embryos is begun (q, fig. 8). It
will be seen, therefore, that not only
do these 8 embryos per zygote all
result from free nuclear cleavages, but
the several embryos develop inde-
pendently from the time the first walls
are organized. The primary embryos
develop without interruption from
their initials, while the rosette em-
bryos are delayed, developing some- oe igs
what later, on an average, than is Hides es pong —
indicated in fig. 8. In the hundreds a, apical cells; s, primary suspen-
of instances that have been examined °° cells; 7, ig sage —
in my investigations of various pines, (latter aaa sariieg sates than
none were found where the 4 primary __ im Stage of embryo shown); ¢1, ¢2,
embryos were combined to produce a and embryonal tubes, which elon-
single embryo, nor were any cases gate and add to suspensor; dia-
found where one of the primary em- S"*™mati¢ reconstructions.
bryos was further split up to give rise to 2 or more embryos.

In the competition which ensues, the rosette embryos play a
very subordinate réle, owing to their unfavorable position and
delayed development. Among the 4 primary embryos, the competi-
tive process elects one embryo from the complex, nearly always the
embryo which develops the longest suspensor, pushing it ahead of

156 BOTANICAL GAZETTE [FEBRUARY ,

its competitors. Embryonic vigor in producing a long suspensor is
the outstanding factor which decides upon the successful embryo.
The mass of embryonal tubes which elongate from the base of the
embryo, as this and the suspensor become more massive, doubtless
assist the successful embryo in checking the others. Usually it is
the embryo foremost in position which is successful in developing
to maturity, but sometimes the second one in position becomes
massive more rapidly and assumes the leading réle, by choking out
the smaller terminalone. Not only must an embryo have a rapidly
developing suspensor, but it must also become many-celled and
massive more quickly than any of the competing embryos.

Vigorous suspensors have been the basis of selection among the
embryos of gymnosperms for so long a period that this organ has
become a large and extensively developed structure, many times
larger than would be necessary without this embryonic competition.
This is true whether the competing embryos come from the same
egg, as in cleavage polyembryony, or the selection occurs between
neighboring zygotes, as among cycads. The remarkably long
suspensor found in nearly all gymnosperms has always been a note-
worthy feature of this group.

Investigation

OTHER PINE SPECIES.—The result of a further investigation of
the embryo development in various species of pines confirmed the
account as announced for Pinus (3). The additional work done
on Pinus Strobus, P. ponderosa, P. edule, and P. resinosa, as well as
a further examination of P. Laricio, P. Banksiana, and P. sylvestris,
makes it practically certain that cleavage polyembryony, the apical
cell development, and the rosette embryos are found quite con-
stantly among all members of this genus.

It might be noted that Pinus sylvestris seems to have a marked
tendency to produce shorter suspensor cells and embryonal tubes
than P. Banksiana, which was taken as the type for the previous
investigation. In P. Laricio the 4 primary embryo units frequently
do not split apart until the primary suspensor cells have stretched
to about half their final length and the first embryonal tubes are
beginning to elongate. Indeed, when some of these earlier stages

1920] BUCHHOLZ—POLY EM BRYONY 157

were examined, the writer’s prediction was that in this species,
at least occasionally, the usual separation into 4 primary embryos
did not occur, but hundreds of embryos dissected out in slightly
later stages (several days older) of material from the same source
failed to reveal even one case without the usual cleavage poly-
embryony.

The rosette embryos of Pinus Laricio are very clear. In many
cases they have suspensors which elongate distinctly, and were
it not for the fact that the dissections clearly show their relation to
the basal plate (bp), these rosette embryos would in some instances
very easily be confused with the primary embryos. On the whole,
the embryos of P. Laricio furnish probably the most satisfactory
type for use in laboratory instruction, both on account of their
clearness in displaying the rosette embryos, and their large size,
which makes them easier to dissect.

ABIETINEAE.—The other genera of Abietineae that were dis-
sected and examined are Cedrus libani, Tsuga canadensis, Abies
balsamea, Picea mariana, Picea excelsa, Larix europea, and Pseudo-
isuga taxifolia, the species investigated representing 7 out of the
9 genera of the Abietineae.

METHOD AND MATERIAL.—The technique was that of dissection
described in detail in the writer’s work on Pinus. No modifica-
tions of these methods were found necessary, but perhaps it should
be repeated that the living material is indispensable for some species.
A study of preserved material is possible, but it is not so satisfactory.
The embryos may be killed and preserved indefinitely, however,
after they have been removed by the methods described. The
proembryo stages must be studied by the well known methods for
making serial sections. The writer is indebted to the following
for the material used during the summer of 1917: W. G. WATERMAN
_ for material of Abies and Tsuga from Frankfort, Michigan; S. D.
Macers for collections of Abies balsamea and Picea mariana from
Marquette, Michigan; D. Hill Nursery Company, of Dundee,
Illinois, for material of Pseudotsuga, Larix, and Tsuga canadensis,
collected on their grounds. Very satisfactory material of Pseudo-
isuga taxifolia was supplied by the Friday Harbor Marine Station
of Puget Sound. During June and July C. T. Hitmers supplied

158 : BOTANICAL GAZETTE [FEBRUARY

weekly collections of the material growing on the University Farm
near Lincoln, Nebraska, as follows: Picea excelsa, Pseudotsuga
taxifolia, Pinus ponderosa, P. sylvestris, P. Laricio, and P. Strobus.
In addition to this, the writer made many trips to various places in
the vicinity of Chicago to secure material of some of these same
species. During the summer of 1918, W. W. Rossins supplied
a collection of Pseudotsuga taxifolia from near Fort Collins, Colo-
rado, and arranged for a collection of Pinus edule from Cortez,
Colorado; and E. J. Kraus made several collections of the cones
of Cedrus libanz from the grounds of the Oregon Agricultural College,
Corvallis, which reached the writer in excellent condition.

Cedrus has almost the same early embryogeny as Pinus. The
primary embryos, however, do not separate until some time after
the suspensor cells and first embryonal tubes have both elongated,
and therefore cling together very much longer than in any species
of Pinus that was investigated. In all the slightly older stages
the embryo units had separated, indicating that cleavage poly-
embryony is likewise a constant feature in Cedrus. An apical
cell stage seems to exist in this genus, and rosette embryos usually
occur, somewhat less developed than in the average pine. The
older suspensor cells collapse soon after separation of the primary
embryo units.

Tsuga canadensis also resembles Pinus very much in its embry-
ogeny. Inthisspecies the embryo units separate into the 4 primary
embryos, yet they cling together longer than in any pine, apparently
about as long as in Cedrus. Cleavage polyembryony occurs regu-
larly. This conclusion is based upon the careful dissection and
examination of the embryos of about 40 ovules of a more advanced
stage, among which no exceptions were found.

Save for their difference in size, Tsuga, Cedrus, and Pinus appear
very similar in the first stages of suspensor formation. In Tsuga,
- however, the rosette cells are very ephemeral; they were not found
to divide before the collapse and disintegration of their contents,
apparently giving no rosette embryos. The suspensor cells also
collapse very soon in Tsuga, leaving only a shred of tissue which
connects the shriveled rosette to the embryo system below. As in
Pinus, the early embryos develop by means of an apical cell.

1920] BUCHHOLZ—POLY EMBRYONY 159

There are from two to four archegonia present in Tsuga, and in
the material studied one or two embryo systems was the usual
number found. The cones were very poorly pollinated, and
doubtless the normal maximum number did not occur. Poly-
embryony, although extensive, is much less pronounced than in
Pinus, for in addition to the small number of archegonia, there are
no functioning rosette embryos.

In Abies the normal product of a fertilized egg is a single embryo.
The group of rosette cells is present, and in a few rare instances a
divided rosette cell and a more advanced rosette embryo were
found. This, as well as the fact that cleavage polyembryony was
also observed in a few cases, shows that this genus stands next to
Cedrus and Tsuga in its similarity to Pinus.

The apical cell stage is doubtless eliminated from the beginning,
for when under normal conditions all of the lower tier of cells com-
bine to produce a single embryo, the terminal cells together are
responsible for producing the tissue. It appears also from an
examination of some of the early embryos that these 4 terminal
cells of the apical group do not always contribute equally to the
cell mass, for one of these 4 terminal cells may frequently be found
decidedly more prolific than the others. Normal apical cell growth,
however, is not possible unless cleavage polyembryony occurs,
as it rarely does.

The suspensor cells and upper embryonal tubes of the secondary
suspensor collapse very soon after elongation. The basal plate
(bp), a deposit formed within the egg over the rosette cells, is very
thick and frequently obstructs a clear view of the rosette cells,
which also collapse early, unless a rosette embryo happens to
develop.

The material of Picea was somewhat limited. The cones that
could be secured of P. mariana were younger than the fertilization
Stage, and a later collection was too old for a satisfactory study of
the early embryo. A number of twigs bearing cones from the
first collection were kept in a tin box in the laboratory for more than
a week, and at the end of this time they were found to contain
embryos in the desirable stages. The P. excelsa cones were very
poorly pollinated, and only a few good embryos were secured from

160 BOTANICAL GAZETTE [FEBRUARY

this species. A study of this material makes it clear that cleavage
polyembryony does not occur, but each archegonium produces
only a single embryo. The group of rosette cells is present, but no
divisions were found within these cells producing rosette embryos,
as they do occasionally in Abies. Picea, therefore, is a step farther
removed from Pinus in having eliminated all traces of cleavage
polyembryony and rosette embryos, except the tier of rosette cells.

Although the available material of Larix was also somewhat
limited, several outstanding features may be described with cer-
tainty. Like Picea and Abies, only one embryo is produced per
archegonium. Except for the different appearance in size and pro-
portion, the embryo of Larix is very similar to that of Picea. The
4 collateral primary suspensor cells become very long and slender,
without the abrupt twists or turns found in the pine suspensor, and
the secondary additions of the suspensor have similar characteris-
tics. _The older divisions of the suspensor collapse as the newer
embryonal tubes elongate from the base of the embryo. A group
of rosette cells is present, but these collapse without forming
embryos, and the basal plates are again large, obstructing a good
view of the former in many cases.

Pseudotsuga furnishes a rather interesting variation from the
embryos already described. This form is like Picea and Larix in
producing only one embryo from each egg. It has no rosette cell,
but the uppermost tier of walled cells elongates to form the sus-
pensor, a condition shown in less than 5 per cent of the pine embryos
(Pinus Banksiana). This occurs as a regular feature in Thuja (12)
and many other conifers. As the suspensor elongates, the contents
of the archegonia shrink and harden, and persist as flattened, deeply
stained structures attached to the upper ends of the transparent
suspensors. A very thick layer of protoplasm or other substance,
in the position which corresponds to the basal plate, stains more
deeply than the remaining regions of the withered archegonia.
Although cleavage polyembryony does not occur, a larger number of
embryos is produced than in Abies, Larix, or Picea. This is due
to the existence of a larger number of archegonia, which range from
5 to 8. The suspensor cells do not collapse early, as in Larix and
Abies, and although the embryos were never found splitting into

1920] BUCHHOLZ—POLYEMBRYONY 161

separate units, the suspensor cells back of the embryo become
easily separated from each other.
Discussion
It will be seen that among the 7 genera of the Abietineae
examined, the last three do not possess cleavage polyembryony
even as an occasional feature, while in Abzes it occurs only in rare
instances. Likewise the rosette ee occur normally in Pinus

eNse,

| ]
10 11 12 13 15
Cedrus Tsuga Abies Picea Larix Pseudo-
tsuga

Fics. 9—15.—Embryos of 7 . of Abietineae, showing intergrading series with
cleavage polyembryony on the one hand (figs. g-11) and its absence on the other
ao 12-1 S) pee embryos in Pinus, Cedrus, and occasionally Abies; diagrams not
and eS and only rarely in Abies, while none of the other forms
shows them even occasionally. Cedrus and Tsuga are most like
Pinus in possessing cleavage polyembryony as a constant feature,
but in the latter the rosette cells do not produce rosette embryos.
Rosette cells, even though they produce no embryos, as in Tsuga,
Larix, and Picea, are clearly homologous with these embryo initials
in Pinus and Cedrus, and represent vestigial structures wherever
they are present. Figs. g—15 illustrate these differences. We have

162 BOTANICAL GAZETTE [FEBRUARY

here a very interesting intergrading series, with Pinus at one end
and Pseudotsuga at the other. There seem to be but two alterna-
tives; either the Picea or Pseudotsuga type of embryo has given
rise to the Pinus type with cleavage polyembryony, or the Picea
embryo is composite in its origin, being made up of the fused or
combined elements that produce the many cleavage embryos in
Pinus.
The writer believes that the pine embryo with its cleavage poly-
embryony is the primitive type, and the following are among the
reasons for this conclusion. The pine embryo ‘combines with
cleavage polyembryony the apical cell, a primitive character, which
clearly recapitulates its semi-pyramidal predecessor at the stem
tip of the fern. To assume that cleavage polyembryony is a derived
feature would take away all phylogenetic significance from this
structure, for the Picea and Pseudotsuga type of embryo have no
~ apical cell. The apical cell could hardly be considered an acci-
dental result of the splitting of a Picea-like embryo. This con-
ception might be entertained if the terminal cell began to display
apical cell characteristics only after separation of the embryos, but
a true apical cell has been shown to exist from the embryo initial
stage, from the time the first walls appear in the proembryo.
The apical cell is present in the adult ferns and in the first stages
- of the pine embryo; it is absent in all adult gymnosperms and like-
wise in angiosperms. This structure has been eliminated in passing
from the lower to the higher vascular plants, and in Picea, Larix,
and Pseudotsuga the apical cell is entirely eliminated from the
beginning of the life history. The embryo development in this
group shows how the apical cell was lost in the evolution of the
Abietineae.

Another reason why the Pinus embryo must be considered the
more primitive type arises from the study of the rosette embryos.
In the Picea embryo are found the vestigial rosette cells, which
never divide, but are clearly homologous with the rosette embryo
initials in the pine. Even in the pine these rosette embryos are
vestigial, but since these rudimentary structures are well developed
in the latter, one would infer that the Pinus type represents the more
primitive condition.

1920] BUCHHOLZ—POLYEMBRYONY 163

Another point in favor of the view that cleavage polyembryony
is a primitive feature is the fact that Pinus is known to be very
old historically. This genus has come to be regarded by paleo-
botanists as one of the very oldest conifers (6). On the other
hand, JEFFREY (9, 10) has reached this same conclusion on the
basis of anatomy.

An additional argument that cleavage polyembryony is primitive
comes from a consideration of the relation that the pine embryo holds
to the known steps in the embryo development of other conifers.
There are several lines of evolution which have arisen from a primi-
tive type of embryo like Pinus. One of these is the abietineous
evolution shown in this investigation, the series beginning with
Pinus and culminating in Pseudotsuga. Another evolutionary
series begins with Pinus, involves some of the Cupressineae and
Taxodineae, and culminates in Gnetales, a line in which cleavage
polyembryony has been retained. Ephedra has a modified form of
cleavage polyembryony, which associates it with Coniferales on ~
the basis of its embryogeny. Other evolutionary lines may have
been derived from the Pinus type of embryo, as described else-
where (3). This is therefore another strong argument that the
pine type of embryo is very primitive.

STRASBURGER (18) has reported that Picea develops only one
embryo per archegonium, and his results are thus verified by this
study, but he did not attach any significance to the question of
whether or not a separation of the embryos occurs. Other investi-
gators in dealing with the embryos of the Abietineae have likewise
failed to make this point clear, and the embryogenies of some genera,
such as Cedrus, Tsuga, Abies, and Larix, have been partially investi-
gated in proembryo stages only.

The proembryo of Pinus has been most extensively studied,
described, and figured by CHAMBERLAIN (4), COULTER and CHAM-
BERLAIN (5), Miss FERGUSON (7), and Miss Kizpaut (11), each
investigator adding a few additional stages and details. The facts
brought out by these investigators are in harmony with the inter-
pretation given to the proembryo in this paper.

The embryogeny of conifers has not usually been undertaken by
morphologists as a distinct problem, but the stages described and

164 BOTANICAL GAZETTE [FEBRUARY

figured were often rather incomplete, being only the by-product of
another investigation. In several instances the proembryo of other
Abietineae has been described as being the same as Pinus, but it is
doubtful if all of the investigators verified every step of the embry-
ogeny included in their account. Four tiers of 4 cells (fig. 6) may
be produced by several methods of division.

Lawson (13) describes 4 tiers of 4 cells each for Pseudotsuga,
but since this species has no rosette group, the exact order of division
and the stages corresponding to figs. 4-7 in Pinus may not be the
same. The writer has not had opportunity to examine the pro-
_ embryo or the earliest stages of the embryo in this species, but it
may be inferred that one of two things happens in the Pseudotsuga
embryo. Either the lowest tier, shown for Pinus in fig. 4p, con-
tinues to divide to give rise to the additional two tiers of cells, or,
more probably, the exact order of division shown in Pinus is carried
out, and it is the rosette tier which elongates. Pinus Banksiana (3)
was found with elongated rosette cells in nearly 5 per cent of the
cases studied. It is very important, therefore, to know whether
the divisions that occur in the proembryo of any species are homolo-
gous with those of Pinus.

Mrvyake (14), in his study of Pick: includes the stages of the
proembryo, and fortunately he figured a stage between fig. 4 and
fig. 5, also between fig. 5 and fig. 6, which proves that the rosette
tier found in this form is identical in origin with that of Pinus,
and the rosettes of these two species are therefore distinctly
homologous.

Tsuga and Abies probably have proembryos identical with
Pinus, in view of the results shown for Picea. Only a few stages
of the proembryo in Tsuga canadensis are definitely known. These
were figured by Murritt (17) as essentially the same as Pinus,
but not illustrated in stages older than fig. 3. Abies balsamea was
‘shown by Miyake (15) to be practically the same as Pinus for the .
‘stages up to and including fig. 4. In view of the similarity of Pinus
and Cedrus in their early embryogeny, there can be little doubt that
the proembryo of the latter develops in very much the same manner.

Only two genera of the Abietineae have not been investigated
in some early stage by the writer. These are Keteleeria and Pseudo-

1920] BUCHHOLZ—POLY EMBRYONY : 165

larix. ‘The later embryo and other anatomical features of Keteleeria
are described by HuTCHINSON (8), but the early embryo still remains
to be studied. Pseudolarix was described by Miyake and
Yasur (16), whose work shows stages in the embryo similar to
figs. 2, 4, and 6, with a figure showing the suspensor cells beginning
to elongate. This species has rosette cells and appears more
slender, but is otherwise like the average of the Abietineae in
the same stage of development before the embryo units separate
(if they do). This embryo is not like Pseudotsuga, therefore, but
probably belongs somewhere in the series (figs. 9-15) between
Tsuga and Picea, the exact position depending upon whether or
not cleavage polyembryony occurs, and whether the rosette cells
give rise to rosette embryos.

Some taxonomists include Pseudotsuga in the same genus with
Tsuga. The results of this investigation show that, on the basis of
the embryogeny at least, there is a fundamental difference between
these two forms, which would entitle Pseudotsuga to be recognized
as a separate genus. The contrasting differences may be sum-
marized as follows. Tsuga has cleavage polyembryony and api-
cal cell growth in its life history, while Pseudotsuga has none of
these features; and while the rosette cells do not produce embryos
in Tsuga, they are either entirely absent in Pseudotsuga or they
elongate to form the suspensor and are not recognizable. The
latter genus has also 5-8 archegonia, while Tsuga usually has a
smaller number (2-4).

It should be noted hat the difference between the embryo
of Pseudotsuga and Tsuga is greater than that between Abies,
Larix, and Picea, and much greater than that between Pinus and
Cedrus. Cedrus, on the other hand, shows little in its early embry-
ogeny which would entitle it to a place as a separate genus, but the
difference between Pinus and Cedrus is nearly as great as that
between Larix and Picea.

Summary
1. Although all species of Pinus have shown a complete
Separation of the 4 primary embryos, this feature of cleavage
polyembryony is not characteristic of all Abietineae.

166 : BOTANICAL GAZETTE [FEBRUARY

2. The cleavages which separate the 8 embryos from each other
are the free nuclear divisions of the proembryo. In forms without
cleavage polyembryony (Picea, and as far as we know concerning |
other forms), cell divisions homologous with those in Pinus occur
in the proembryo.

3. The embryos of the Abietineae may be arranged in an inter-
grading series, with Pinus at one end and Pseudotsuga at the other,
on the basis of the occurrence of cleavage polyembryony, rosette
embryos, and the apical cell. The rosette embryos and their
vestiges, the rosette cells, are gradually 2 em as we pass from
Pinus to Pseudotsuga.

4. Cleavage polyembryony, mosette embryos, and the apical
cell mark a primitive type of embryo development.

5. The embryo development of this group shows how the apical
cell was lost in the evolution of the Abietineae.

6. On the basis of embryogeny Pseudotsuga is unique and is
entitled to rank as a separate genus.

This study was begun at the Hull Botanical Laboratories in
- the summer of 1917 and is the result of a preliminary study of the
embryo material of these conifers. More detailed descriptions
of the embryos with illustrations will appear later. The writer
takes pleasure in acknowledging his indebtedness to Dr. C. J.
CHAMBERLAIN for valuable council in getting this investigation
under way.

UNIVERSITY OF ARKANSAS
FAYETTEVILLE, ARK.

1920] BUCHHOLZ—POLYEMBRYONY 167

vv

“nN

oo

LITERATURE CITED

Brown, R., in Capt. Philip P. King’s “Survey of the western and inter-
tropical coasts of Australia,’ London, 1826, Appendix B, p. 557; also
Ann. Sci. Nat. I 8:211. 1826.

, Plurality and development of embryo in the seeds of Coniferae.
Rep. Brit. Assoc. Ady. Sci. 1835: 596, 597; reprinted in Ann. Sci. Nat. IT
20:193. 1843; Same paper reprinted with postscript and plate, Ann. Nat.
Hist. 13:138-374. 1844

Bucuuotz, J. T. Sumpeesee Fs early embryo of Pinus. Bot. Gaz. 66:
185-228. pls. é20. figs. 3. 19

CHAMBERLAIN, C. J., Oeceica: in Pinus Laricio. Bot. GAz. 27:268-280.
pls. 3. 1

- COULTER, t M., and CHAMBERLAIN, C. J., Morphology of Spermatophytes.

Part I. Chicag: Igol.
——-—, Morphology of gymnosperms. Chicago. 1910.

é Frncuson, MARGARET C., Contzibatsins: to the ae history of Pinus, jie
nd

special reference to sporogenesis, the d phytes,
fertilization. Proc. Wash. Acad. Sci. 6:1-202. pis. I-24

1904.
. Hurcuinson, A. H., Morphology of Keteleeria Fortunei. ‘Bor. GAZ. 63:

124-135. pls. 7,8. 1917.

JEFFREY, E. C., The comparative anatomy of the Coniferales II. The
Abietineae. Mem. Boston Soc. Nat. Hist. 6:1-37. pls. 1-7. 1904.
———, The anatomy of woody plants. Chicago. 19

17. .
: Krai, N. JOHANNA, Development of gee: in the proembryo of Pinus

Laricio. Bor. GAz. 44:102-107. pls. 8

190
- Lanp, W. J. G., A morphological study of T aie: Bor. Gaz. 34:249-259.

pls. 6-8. 1902.
Lawson, A. A., Gametophytes and embryo of Pseudotsuga Douglasit.
Ann. Botany 23:163-180. pls. 12-14. 1900.

- Mryakg, K., On the development of the sexual organs and fertilization in.

Picea excelsa. Ann. Botany 17:351-352. pls. 4. 1903

- —— —, Contributions to the fertilization and embryogeny of Abies bal-

samea. Beih. Bot. Centralbl. 14:134-144. pls. 6-8. 1903.
Miyake, K., and Yasui, Kono, On the gametophytes and embryo of
Pseudolarix. Ann. Botany 25:639-647. pl. 48. 1911.

URRILL, Wa. A., Development of the archegonium and fertilization in
the bao spruce (Tsuga canadensis Carr.). Ann. Botany 14:583-607.
pls. 3

goo
18. Biisereee. E., Die Coniferen und Gnetaceen. Jena. 1872.

CHEMICAL AND PHYSICAL CHANGES DURING
GEOTROPIC RESPONSE

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 262
THomas G. PHILLIPS
Introduction

The work reported in this paper was undertaken with the object
of making as complete a study as possible of all the chemical and
physical processes that might be involved in geotropic response.
It was hoped in this way not only to add something to the knowl-
edge of the mechanics of geotropic bending, but also to find some
quantitative differences which are associated with ‘the differing
rates of growth of the two flanks of the responding organ. It
became necessary to drop the work before it was complete. Such
results as were obtained are reported in the hope that they may
prove of some value to others interested in the problem.

Several studies of one or more of the factors which might be
involved have been made. Kraus (8) found that the water content
of the convex flank of organs stimulated geotropically is greater
even before bending begins. He also made determinations of
reducing sugars and titration acidity on the juice expressed from
the organs. He concluded that when a stem capable of negative
geotropic response is laid horizontally, increased sugar formation
begins at once, and the amount of free acid decreases. This occurs
especially on the lower side. There is a movement of water from
the upper to the lower side. Thus the concentration of sugar in the
juice of the lower side becomes less than in that of the upper. e

Miss Scutry (9), working with shoots of etiolated Vicia Faba
seedlings, found rather complex changes in the titration acidity
after exposure to gravity. First the concave side was more acid,
then the convex, then they became about equal while bending was in
progress. After the tip had passed the vertical, the concave side
became the more acid, but this difference gradually disappeared.
She found the water content somewhat greater on the convex side,
Botanical Gazette, vol. 69] [168

1920] PHILLIPS—GEOTROPISM 169

but the samples were taken after bending was practically complete.
The percentage of sugar in the convex flank was considerably
lower than in the concave, after an exposure of 45 minutes.

In various roots exposed to. gravity CzAPEK (3) found an
accumulation of intermediate products of oxidation of certain
amino acids, due to the presence of an antienzyme which inhibits
the normal oxidation of these substances. He found no differences
between the upper and lower flanks in this respect. GROTTIAN (7)
and GRAFE and LINSBAUER (5) were unable to confirm CzAPEK’s
results. The latter workers (6) found that geotropic response
causes no differences in catalase activity.

SMALL (10) found increased permeability in the cortical cells of
both sides of root tips of Vicia Faba when exposed to gravity.
The permeability of the lower sides showed a greater increase
than that of the upper side.

Changes in the viscosity of the protoplasm during geotropic
stimulation were studied by WeEBER (11), who found that the
viscosity is lessened. ZOLLIHOFER (12) was unable to confirm
this result, and states that the method used is subject to large experi-
mental errors.

Experimental work

The first material used in this work was nodes of corn that had
completed their growth. The node was cut out, together with
about half the internodes above and below, and the sheath removed.
The node was then planted horizontally in a bank of moist sand in
a box from which light was excluded. This material is especially
good because no growth occurs aside from that due to the action
of gravity, and because the region which bends in most cases is
very clearly defined. After exposure to gravity this region was cut
out and divided into upper and lower flanks. There are at least
two objections to the use of corn nodes. First, suitable material
can be obtained only during a comparatively short time each year.
Second, whether a given node will respond to gravity.is very un-
certain. Some nodes that apparently were healthy and in good
condition did not respond at all, and others which showed no evi-
dent differences responded readily. This makes practically impos-
sible a study of the oF before visible bending begins.

170 BOTANICAL GAZETTE [FEBRUARY

Etiolated Vicia Faba seedlings were used for the later work.
For the moisture and titration acidity determinations the plants
were grown in moist sphagnum in pans. When the shoots had
reached a suitable length (6-8 cm.) they were exposed to gravity by
setting the pans on edge. In collecting the material, the leaf was
removed and the stem divided as accurately as possible into upper
and lower flanks. The terminal 3-4 cm. were used. For the other
work the plants were grown in moist sawdust in a dark cool room.

TABLE I
MOISTURE AND ACIDITY IN CORN NODES EXPOSED TO GRAVITY
MotsTuRE Acrpiry IN cc. 0.05 N NaOH
Tee’ oF PER GM. FRESH WEIGHT
EXPOSURE
Upper flank | Lower flank | Difference | Upper flank | Lower flank | Difference
(percentage) | (percentage) | (percentage)

Hours : :
or se ok 86.68 87.10 +0.42 °.49 0.48 —G.01
Go ees 87.00 86.83 —0O.17 0.47 0.47 eer ses
Ass 6.85 6.98 +0.13 0.47 0.53 +o0.06
GAS 87.09 7.18 +0.09 0.51 ©.59 +0.08
se RO ne a 84.97 4.43 —0.54 0.46 0.48 +0.02
pS ety: 4.04 85.10 +1.06 0.51 0.54 +0.03

Re 3.80 3.19 —o.61 ©.49 0.50 +o0.01
ey aparare 83.10 2.72 —o.38 0.57 0.5 +0.02
Se Cae ese ats F 5.50 4.61 —o.89 0.47 0.46 ~ 0.01
a ee SoS 4.24 4.26 +0.02 0.47 ©.54 +0.07
Se... sk: 3.50 3.71 +o.21 0.38 0.48 +0.10
1. 2.39 2.79 +o. 0.51 0.55 +0.04
1 ees 2.35 3.40 +1.05 0.61 0.65 +0.04
ry eee ep nea ge 2.31 2.71 +0.40 0.67 °.70 +0.03
PE ety 83.73 2,90 —0.74 0.55 0.57 +0.02
a es 32.97 2. —90.07 0.58 0.65 +0.07
Pe eS. 31.39 2.19 +o.80 0.64 0.57 —0.07
ee ae 1.44 2.44 +1.00 0.65 °.76 +0.11

When they had reached a suitable length they were transferred to
boards where they were held in place by pieces of cork. The
boards were placed upright in a large galvanized iron container,
under a spray. They were kept in this position for at least 24 hours,
and then exposed to gravity by rotating the board through go”.
In the determination of moisture the corn nodes were dried
to constarit weight in vacuo at 80°C. The samples varied in
weight from 2 to 5 gm., according to the number and size of the
nodes used. Table I gives the results of the series in which the

1920] PHILLIPS—GEOTROPISM a7t

nodes were exposed to gravity for varying lengths of time, from
3 to 27 hours. In the last column, + is in favor of the convex side
and — in favor of the concave. This method of statement is used
in all the tables. As already mentioned, corn nodes are not at all
uniform in their response to gravity, and because of this fact a
second set was run in which nodes that had bent approximately
to the degree indicated were used. The results will be found in
table IT.

TABLE II
MOISTURE AND ACIDITY IN CORN NODES EXPOSED TO GRAVITY
MolsturE AcIpITy IN cc. 0.05 NW NaOH
DEGREE OF ee
BENDING i
Upper ink Lower flank | Difference | Upper flank | Lower flank | Difference
(percentage) | (percentage) | (percentage)
ae eae 82.41 81.30 —1I.1I 0.62 0.65 +0.03
egies: 80.27 .08 —o.19 0.72 0.75 +0.03
ae acre 81.19 80. —0.75 0.60 0.73 +0.13
Boe oe, 84.68 84.21 —o °. 0.63 +0.03
[12 80.42 80.77 +0. 35 0.75 0.83 +0.08
2 Oye er eet 86.04 86.3 +o. or 0.56 °.60 +0.04
| eae mane 86.31 87.63 +1.32 0.65 0:72 +0.07
ca ee 85.13 87. “2.47 0.66 0.80 +0.14
Me a 87.12 89.5 +2.40 0.80 0.76 —0.
SS Psy ot, 87.52 89.20 sap Sk & 0.66 0.71 +0.05

Individual differences in moisture content are so great that
different samples cannot be compared. It is only possible to
compare opposite flanks of the same sample. In general the
differences are slight, and in view of the high percentage of moisture
present they may not be significant. There are some features of
the results which are of interest, however, especially when the two
sets are compared. In the time of exposure set the differences are
variable, but in general favor the convex side up to 9 hours of
exposure. At 12 and 15 hours, when bending is well started, there
is a decided difference in favor of the concave side. At 18, 21, and
27 hours the convex side contains much more moisture. The results
at 24 hours appear to be anomalous, especially as no corresponding
change is found in the other set. In the degree of bending set the
differences are more regular and more marked. During the early
Stages of bending the concave flank contains the more moisture, but

172 BOTANICAL GAZETTE [FEBRUARY
as bending proceeds the convex flank contains more water. The
same difference is indicated in the time of exposure set, but because
of irregularities in the response of the nodes, it is not so obvious.
The results with Vicia Faba shoots are given in table III.
The fresh samples weighed about 1 gm. They were dried to con-
stant weight at 100-102°C. The differences are so small and so

TABLE III
MOISTURE AND AcipiITy IN Vicia Faba SHOOTS EXPOSED TO GRAVITY
i capeons Acipity IN cc. 0.05 WN NaOH
TIME OF PER GM, FRESH WEIGHT
EXPOSURE
Upper flank | Lower flank | Difference | Upper flank | Lower flank | Difference
(percentage) | (percentage) | (percentage)

15 minutes... 93-35 63.950 pee 1.40 ae —0.25
15 minutes 03-33 CES EL ear irae ete 1.18 T1G [hs ee
30 minutes.. 92.43 92.50 +0.07 1.10 1.15 +0.05
30 minutes. 93-25 4.43 —o.12 0.99 1.05 +o.06
45 minutes 92.48 QI .63 —o.85 1.05 1.72 +0.07
45 minutes 92.67 O2.73 +0.06 £07 0.94 — Out

Pours. 2 93.02 93.19 +0.17 1.16 1.19 +0,.03

t hoger... .. 92.40 92.50 +o0.10 1.20 1.16 —o.

2 hours 91.53 gI.50 —0.0 1.54 1.58 +0.04

2 hours 93. 93.03 +0.03 1.39 1.37 —90.02

3 hours 92.50 92.65 +0.15 tis 1.20 +0.02

3 ho 92.13 92.45 +0. 32 7,28 1.10 —0.05

5 hours 92.50 92.80 +0. 30 1.23 1.17 —o.06

5 hours 92.95 93-15 +0. 20 1.18 1.10 —o.08

7 hours 92.70 92.63 —0.07 1/02 0.91 “ores

7 hours 92.60 7 ol co ape Wears Pee an 1.43 1.08 0.05

9 hours 92.37 92.70 +0.33 re 1.14 +o.01

9 ho 92.87 92.93. +0.06 1125 t.22 —0.03
rr hours 02.35 Q2.00 —0.35 Las F15 —9.02
1r hours 92.65 p69 oe 1.33 1.19 +0.06
13 hours 92.69 92.80 +0.11 4,35 1.12 —0.03
13 ho’ 92.87 92.73 —0o.14 1.15 42 —0.03
17 hours 92.97 92.89 —o. $k3 1.26 +0. 53
17 hours 92.25 Q2.27 +0.02 4.33 1.41 +0.09
21 hours... 91.60 G00 foe Se > 1.11 —90.04
21 hours.....| 93.00 93.07 +0.07 ©.97 0.95 —9.02

irregular as to be insignificant. At the periods from 1 to 9 hours the
convex side seems to contain, in general, a little more moisture, but
the differences are too slight to serve as a basis for any conclusions.

For the determination of titration acidity the samples were
ground in a mortar with sand which had been treated with HCl
and washed free from acid. Fifty cc. of water was added and the
mixture titrated to phenolphthalein with 0.05 N NaOH. Blanks

%
_ 1920] PHILLIPS—GEOTROPISM 173

were run on the sand and water, and were used to correct the
results. There was not enough color in the material to interfere
seriously with the phenolphthalein endpoint, but the endpoint is
somewhat slow, and, especially with material containing so little
acid, the unavoidable errors are apt to cause differences which
represent a large percentage of the total titration. The results for
corn nodes, calculated as cubic centimeters 0.05 N NaOH per
gram of fresh material, are given in tables I and II. The differ-
ences found between the two flanks are small. The convex side
seems quite uniformly to be the more acid.

A few measurements of the hydrogen ion concentration of the
press juice of corn nodes which had bent from 5° to 15° were
obtained. The measurements were made electrometrically, using
a modified form of the Barendrecht electrode. The following P,
values were obtained, that for the upper flank being given first in
each case: 4.919, 5.012; 5.136, 5.246; 5.104, 5.198. In these
three cases, therefore, the hydrogen ion concentration of the juice
of the concave flank was the greater, although, as has been noted,
the titration acidity varied quite uniformly in the other direction.

The titration results with Vicia Faba are given in table III.
The differences are slight and irregular, and do not correspond at
all closely with those reported by Miss ScHtry.

Determinations of hydrogen ion concentration, and electrometric
titrations, were made on the press juice of the upper and lower
flanks of Vicia Faba seedlings that had been exposed to gravity.
The material was frozen immediately after collection. A special
hand press was used which would remove the juice very completely
from samples containing not more than ro gm. of the fresh material.
Five cc. of the juice was taken for the determination. The hydro-
gen ion concentration was determined immediately, after adding
1 cc. of o.10 N NaOH free from carbonates. This is practically
the method used by EmstANDER (4) in his work with beer. Pre-
liminary experiments showed that the part of the titration curve
including these two points is always, for this material, the straight
line part of the curve which crosses the neutral line. Usually the
two points obtained were on opposite sides of neutrality, so that the
cubic centimeters of 0.10 N NaOH required to titrate to P,=7.0

174 BOTANICAL GAZETTE [FEBRUARY .

could be calculated by a In only one case was it
necessary to extrapolate.

In table IV are given the P,, values of the press juice, and the
cubic centimeters of 0.10 NV NaOH required to bring 5 cc. of the
- juice to the neutral point. The results obtained on right and left _
halves of seedlings not exposed to gravity are given in the last
two lines of the table. These results show the magnitude of the
differences that might arise from other causes than the action of
gravity, such as actual differences between two sides of a plant,
and errors in measurement. In a few cases the differences found

TABLE IV
ELECTROMETRIC DETERMINATIONS ON PRESS JUICE OF Vicia Faba SHOOTS EXPOSED

Tare oe HypROGEN ION EXPONENT ing = Ayal NaOH
EXPOSURE
Upper flank | Lower flank | Difference | Upper flank | Lower flank | Difference
30 minutes... 6.124 6.198 +0.074 °.81 0.77 —0.04
30 minutes...| 6.122 6.060 0.062 0.89 1.05 +0.16
thoear, 2). 6.127 6.207. | +0.080 o.81 0.71 3,10
t Hout... <&. 6.137 6.092 | ~0.045 0.83 0.92 +0.09
2hours.....| 6.144 6.198 | +0.054 0.75 0.77 +0.02
a hour. i. 3 6. 432 6.160 | +0.028 °.79 0.75 —0.0
4hours.....} 6.203 6 ~0.143_ 0.74 °.81 +0,..07
4hours.....| 6.170 6.193 | +0.023 0.72 0.75 +0.03
Not exposed.| 6.079 6.102 | +0.023 0.88 0.82 —o.06
ot exposed.| 6.048 6.103 | +0.055 0.87 °.79 —o.08

between the flanks of plants acted on by gravity are greater than
those in the blank determinations, but where this is the case the
differences are not regular in direction.

The plan of the work included as complete a study as possible
of the various oxidizing enzymes. Only the catalase had been
studied when it became necessary to discontinue the work. Deter-
minations of catalase activity were made by the method of APPLE-
MAN (1), as modified and used by CROCKER and HARRINGTON (2).
Catalase activity decreases from the tip downward, and it is not
exactly proportional to the weight of the sample. It was not
possible entirely to avoid the errors from both of these sources.
The following method was used. After exposure to gravity the

*

1920] PHILLIPS—GEOTROPISM 175

shoot was divided as accurately as possible into upper and lower
flanks. A sample was cut from one of the flanks, starting at the
tip and going as far as was necessary to obtain exactly 0.200 gm.
The other flank was left attached to the plant, and kept in a moist
dark place while catalase was determined in the first. sample. —
The second flank was then sampled in the same way as the first,
and its catalase content determined. Six plants were used for each
period of exposure. The catalase content of the upper flank of
three of these was determined first, that of the lower flank of the
other three first. The o.200 gm. sample was ground for 2 minutes
in a mortar with sand and a little CaCO,. It was then washed into
the apparatus with 15 cc. of water. After the apparatus had
reached the temperature of the bath, 5 cc. of H,O, (dioxygen),
neutralized with a little CaCO;, was added. Shaking was begun
at once, and readings of the volume of oxygen evolved were taken
every minute for 10 minutes. The bath was kept at 25°C. and the
air temperature did not change significantly during any single set
of determinations.

The results given in table V are the cubic centimeters of oxygen
evolved in 10 minutes. The average of the results for each of the
periods of exposure is in favor of the upper flank, but only in the
case of the 1 hour samples were all the results in this direction. In
the other sets the individual results vary so widely that no conclu-
sions can be drawn from the averages.

For chemical analysis samples of about too gm. fresh weight
were used. These were collected in flasks containing 0.5 gm.
CaCO, and sufficient alcohol so that the final concentration was
approximately 80 per cent. It was during the collection of the
last of these samples that it became necessary to drop the work.

In order that the material might not be lost, H. A. Jones consented

to complete the collection and carry out the analyses. The writer
wishes to express his thanks to Dr. Jones for his kindness in making
this addition to the data possible.

The soluble and insoluble portions were separated, and total
solids determined in each. Sugars were determined as follows.
Aliquots of the extract were evaporated to remove alcohol, taken up
with water, and clarified with basic lead acetate. The excess lead

176 BOTANICAL GAZETTE _ [FEBRUARY

was removed by Na,SO,. In the filtrate reducing sugars were
determined before and after subjecting it to the standard method
for the hydrolysis of sucrose by HCl. The Bertrand titration
method was used for determining the amounts of copper reduced.
The results are expressed as glucose and sucrose respectively,
although it is recognized that other sugars are undoubtedly included.
Total nitrogen was determined in both the soluble and insoluble

TABLE V
CATALASE ACTIVITY IN SHOOTS OF Vicia Faba EXPOSED TO
GRAVITY (EXPRESSED AS CUBIC CENTIMETERS OF OXY-
EN LIBERATED BY 0.20 GM. OF MATERIAL)

Time of exposure Upper flank | Lower flank | Difference
Sp Witites. <5 0 yA 7.80 +0.65
so Inmites 23 8.20 8.00 —o.2
a0 mmutes: bs. : 8.45 7.50 —0.95
Ae Haitene i. 8.40 6.30 2.10
40 DANVULES © oS ok 9:00 10.70 +1.70
30 UES So ee 740 6.70 —0o.40
O08 CS 9.85 8.65 —1.20
COE hee ass 9.40 8.20 —1.20
Piour,. 2. es. : 12.20 11.40 —o.80
thot 6 a 10.20 9.00 —1.20
PRONE. So ise 8.00 7.50 —~0.50
© Rar. cls 8.80 8.70 —0o.10
PIONS oe is 9.85 10.05 +0.20
SOON is 8.80 9.00 +0.20
a hodte see 10.10 9.95 —0.15
TO oS. 11.30 II.00 —0.30
2 Done. a, oe 4.10 7.4 +0.30
a hS0re ok. 8.60 7.60 —1.00
eons... 0:25 9.30 +0.05
AMON 7.40 716 —o.
“4 Rous. ices e155 6.60 +1.45
geen ane 8.80 8.50 —0.30
enon 9710 6.60 —0o.50
Aedes ss 8.65 7.60 —1.05

portions by the Kjeldahl method. The results are given in table VI.
The differences in direct reducing sugars, ‘glucose,’ are com-
paratively slight. Those in reducing sugars formed on hydrolysis,
“sucrose,” are considerably greater, especially when figured as
percentages of the total. It is to be remembered, however, that the
total amount of sucrose is relatively small, and that the errors in
both determinations may accumulate in that of sucrose. It seems

4

S

1920] PHILLIPS—GEOTROPISM 177

to be impossible to correlate the differences found with the process
of bending. The same may be said of the distribution of nitrogen.

Summary
Definite moisture changes accompany geotropic bending in corn
nodes. During the early stages of bending there is a greater
percentage of moisture in the concave flank. When the process

TABLE VI

ANALYSES OF Vicia Faba SHOOTS EXPOSED TO GRAVITY
IN PERCENTAGE OF FRESH WEIGHT

Bess, | Yer | tr | vcwee | War | aT | vie
Glucose Sucrose
30 minutes... 2.16 2.55 =O, OL ©.450 0.279 [0.171
SOF. oo: 1.47 1.40 —0.07 ©. 187 0.287 | +0.100
2 hours 1.56 1.67 +o.11 ©. 221 0.269 | +0.048
4 hours 1.37 1.41 +0.04 °.449 0.289 | —o.160
Total sugars Moisture
30 minutes 2.61 2.43 —o.18 Q1.57 92.39 +0.82
* boar... .:, 1.65 1.69 +0.04 92.54 92.46 —o.08
2 hours 1.78 1.04 +o.16 1.62 gr .82 +0.20
4 hours 1.82 1.70 —o.12 OI .93 92.13 +0.20
Soluble nitrogen Insoluble nitrogen
3° minutes ©. 204 0.301 | +0.007 0.302 0.284 | —o.o18
ian een ©. 261 0.259 0.002 ©. 303 306 0.003
2 hours 0.279 0.305 | +0.026 0.314 0.296 | —o.018
4 hours ©. 264 0.258 2.349 0.324 | —0.025

has developed the percentage of water is greater in the convex
flank

Although titration acidity is greater in the convex flank, the
differences are very slight. The results on hydrogen ion concen-
tration, although uniform in direction, are not numerous enough to
serve as a basis for conclusions.

It is impossible, with the data obtained, to correlate the geo-
tropic bending of etiolated Vicia Faba shoots with differences in

178

BOTANICAL GAZETTE [FEBRUARY

moisture, titration acidity, hydrogen ion concentration, catalase
activity, or the distribution of sugars and nitrogen containing
substances.

The writer wishes to express his thanks to Dr. WM. CROCKER

for his continued interest in the work, and for his many helpful
suggestions.

I.

N
.

\
w

Onto STATE UNIVERSITY
CoLumsBus, Onto

LITERATURE CITED

APPLEMAN, C.O., Some observations on catalase. Bort. Gaz. 50:182-192.
IQIo.

CROcKER, Wa., and Harrincton, G. T., Catalase and oxidase content of
seeds in rein to dormancy, age, vitality, and respiration. Jour. Agric.
Res. 15:137-174. 1918.

- Czarek, F., Oxidative Stofiwechselvorginge bei pflanzlichen Reizreac-

tionen. Sahchy: Wiss. Bot. 43:361-467. 1906 pas
EMSLANDER, FR., Die Wasserstoff Ionen Konzentration im Biere und bei
dessen Bereitung. Kolloid Z. 14:44-48. 191

4
. GraFeE, V., and LinsBav_er, K., Zur Kentniss der Stoffwechselinderungen

bei geotropischer Reizung. I. Anz. Kais. Akad. Wiss. Wien 12:202-203-
1909; abs. in Bot. Centralbl. 113:525

I. Anz. Kais. Akad. Wiss. Wien 20: 364. 1910; abs. in Bot.
Centralbl. 116: Zt
GRoTTiAN, WALTER, Beitrige zur Kenntnis der Geotropismus. Beih.
Bot. Centralbl. 24:255-285. 1908.
Kraus, Grecor, Uber die Wasserverteilung in der Pflanze. Abh. Naturf.
Gesells. Halle 15:1880.
Scutey, Eva O., Chemical and poet sei in geotropic stimulation
and response. Bor. Gaz. 56:480-4
SMALL, James, Geotropism and the Weber-Fechner law. Ann. Botany
31:313-314. 1917.
WesER, G., Aenderung der ane bei geotropischer Reizung.
Oesterr. Bot. Zeitschr. 64:434-442. 19
ZOLLIHOFER, Ciara, Uber die Witkung ‘die Schwerkraft auf die Plasma-
viscositaét. Ber. Dieta. Bot. Gesells. 35: 291-298. 1917; abs. in Physiol.
Abs. 32210.

EQ ION OF SCUTELLUM AND HOMOLOGY
OF COLEOPTILE IN MAIZE
(WITH ELEVEN FIGURES)
PAUL WEATHERWAX

The homologies of the grass embryo and their bearing upon
ideas of the phylogenetic relationship of monocotyledonous and
dicotyledonous plants have been subjects of study and discussion
for a long time, and although most botanists are fairly well agreed
upon most phases of the question, some points are still subject to
controversy. It is realized that evidences drawn from a single
species as highly specialized as maize will not go far toward the
making or the breaking of a theory, but two things have been
observed in the structure and development of the embryo of Zea ~
Mays that seem to have a definite bearing upon the subject, and
these are offered for what they may be wor

The history of the subject has been fully reviewed, and certain
sharply contrasted opinions have been presented recently by
WorsbDELL and by CouLTer and Lanp. Further reference to the
voluminous literature seems unnecessary here, and only those points
to which the information at hand is related will be considered.

CouLTEeR and Lanp' maintain that the scutellum of the grass
embryo is a lateral organ, the equivalent of the foliage leaf. The
epiblast represents the cotyledon that was lost in the evolution
from the monocotyledonous condition, and the coleoptile is the
third leaf. Opposed to this is WorsDELL’s? contention that the
cotyledon, which he considers terminal in origin, is the lamina, and
the coleoptile is the ligule, of a single foliage leaf, whose sheath was
present only in early stages of development. The epiblast is said
to be the equivalent of the auricles of the foliage leaf. The princi-
pal evidences brought to the support of this view are the double

*Coutter, J. M., and Lanp, W. J. G., The origin of monocotyledony, II.
Monocotyledony in grasses. Ann. Mo. Bot. Gard. 2:175-183. 1915.

* WorsvELL, W. C., The morphology of the monocotyledonous embryo and that
of the grass in purticuias. Ann. Botany 30: 509-524. 1916.
179] [Botanical Gazettee, vol. 69

180 BOTANICAL GAZETTE [FEBRUARY

nature of the vascular system of the coleoptile, the bifid character
of the epiblast in some grasses, and the forked coleoptile found in a
few seedlings of maize. As a background for these details is the
idea that the monocotyledonous condition is the primitive one.
The first piece of evidence that I have to offer on these questions
is in the form of a series of steps in the development of the embryo
of maize (figs. 1-7). These stages have often been observed and

Fics. 1-7.—Figs. 1-6, steps in development of embryo: C, cotyledon; S, sus-
pensor; Co, he Z, foliage leaf; R, root; RS, root sheath; X15; fig. 7, longi-
tudinal section of nearly mature embryo: S, scutellum; Co, coleoptile; a ‘foliage
leaf; RC, root cap; RS, root sheath; Su, suspensor; X15.

discussed more or less abstractly, but I have failed to find a complete
series figured. In so far as appearances may be trusted, no. evi-
dence is clearer than this series. The appearance of the mature
embryo (fig. 7) leaves little doubt of the terminal position of the
plumule, and preceding stages of development bear this out fully;
the cotyledon is never terminal, even in the earliest stages. As
soon as the young embryo begins to differentiate, so that anything

1920] WEATHERWAX—MAIZE 181

that may be called a cotyledon is visible (fig. 1), the whole structure
has an asymmetrical form due to the more rapid development
laterally of the cotyledon, and subsequent steps emphasize this
(figs. 2-7). That the coleoptile is at first directed horizontally or
downward, as is emphasized by WorsDELL, is of little significance;
morphological position cannot always be determined geometrically.
Moreover, WorsDELL’s? figures, taken from another authority in

Fics. 8-11.—Figs. 8, 9, transverse sections of embryo through plumule: VS, vas-
cular cake of scutellum; VC, vascular strands of coleoptile; L, foliage leaf; C, point
of union between two sides of coleoptile, forming closed sheath; sections of embryo
of liguleless variety in no essential way different from these; 15; fig. 10, germi-
nating seed of liguleless maize: coleoptile present and normal; fig. 1 1, seedling of
maize, showing forked coleoptile.

substantiation of his position, are only the upper parts of embryos;
if we attach to the figures the lower parts of the corresponding stages
of development of the embryo of any typical grass, the continuity
of cotyledon, hypocotyl; and suspensor as the axis of the embryo
is evident.

The second point in support of the view taken by CouLTER and
Lanp is afforded by the embryo of a liguleless variety of maize
isolated by EMERSON a few years ago. These plants are like those
of ordinary maize, except that they breed true for the absence of

*Ibid., fig. 3, A-E, p. 511.

182 BOTANICAL GAZETTE [FEBRUARY

ligules and auricles. A few of the plants tend to produce at least
rudimentary ligules on the uppermost leaves, but they are regu-
larly absent from the lower leaves, and the condition might reason-
ably be expected to extend to the cotyledon also. An examination
of the embryo and of the seedling, however, shows the coleoptile
to be present and normally developed (figs. 8-10). While this fact
cannot be accepted as a proof of anything, it should at least not be
overlooked in considering the question.

WorRSDELL has probably given undue emphasis to the arrange-
ment of the vascular strands of the coleoptile and to the forked
tip of this organ in some seedlings of maize (fig. 11). It is true that
the coleoptile has two vascular strands bilaterally placed (figs. 8, 9),
while the foliage leaf has several strands equally distributed; but
this modification in vascular anatomy is no more significant than
that shown in the scutellum (figs. 8, 9), in a prophyllum, or in the
palea of many grasses, all of which tend to have their vascular ele-
ments present in two groups, and yet all of which are considered
modified foliage leaves. The forked coleoptile is a common occur-
rence often noted by anyone having occasion to examine a large
number of seedlings of maize, and it is due to a superficial set of
conditions. The coleoptile begins to develop as an open sheath
(figs. 2-4), the edges of which soon unite to form a closed structure;
but the line of this union is always visible (figs. 8, 9), especially
near the top of the sheath. Too much significance must not be
attached to the nature of the mechanical rupture of this structure
by the elongating plumule. If the union of the two sides has not
been very firm, and it usually is not, the structure will split on one
side only; but if the two sides are firmly grown together, the coleop-
tile may split for a short distance down two sides, producing the
forked coleoptile (fig. 11). The relation between this occurrence
and the duplex ligules of some grasses, or the t wo stipules of some
other plants, is too remote to merit consideration.

It may be said, therefore, that the evidences derived from the
structure and development of the maize embryo, including that of
the liguleless mutant, favor the idea that the coleoptile is the homo-
logue of a foliage leaf, and that the cotyledon is a lateral organ.

INDIANA UNIVERSITY

BLooMINGTON, INp.

>

CURRENT LITERATURE

NOTES FOR STUUGnNTs

Ecological terms and concepts.—Ecology, one of the latest branches of

of note, not so much for their contributions to nomenclature, as to their logical
division of the subject and their criticism of the mistakes of the past. This
seems particularly true of an article by PAVILLARD,’ in which he begins with a
historical and critical sketch of conditions in the past, and proceeds with an
analysis of the scope of plant geography. Here it is suggested that it would
be desirable for all to follow the practice of the Swiss school and employ the
designation “geobotany” suggested by GRISEBACH in 1866. Two main
divisions of the science are then made, resting upon the two fundamental
units of the species and the association. It is further suggested that the lat-

subdivisions of the subject: (1) Floristic geobotany, (2) Genetic geobotan
(3) Ecologic geobotany, (4) Floristic phytosociology, - Genetic aie
sociology, and (6) Ecologic phytosociology. Whether this classification be
universally adopted or not, it has much to recommend it in logical a
and, further, it shows considerable agreement with the best usage of the pas

The content of floristic geobotany would remain the same as for fete
plant geography as delimited by WARMING in 1895, while ecologic geobotany
would not differ materially from the autecology of ScHROTER in giving emphasis
to the relationship of the individual species to its habitat and the growth form
by which it responds to its environment. To genetic geobotany would
referred such questions as the geographical aspect of the origin of species,
ile roger and endemism.

In the division devoted to problems connected with the plant association,
the use of the term phytosociology or plant sociology was proposed by JACCARD
in 1910, and employed in a more limited sense by HaRPER.? The second and
third subdivisions seem about equivalent to ScHROTER’s synecology, genetic

* PAVILLARD, J., Les progrés de la nomenclature dans la géographie botanique.
Ann. Geogr. 27:401-415. 1918

* Harper, R. M., The new science of plant sociology. Sci. Monthly 4:456-460.
Igt7.

183

184 BOTANICAL GAZETTE [FEBRUARY

phytosociology being almost exactly the same as CowLEs’s} physiographic
ecology, while ecologic phytosociology corresponds very closely to WARMING’S
ecological plant geography. To floristic phytosociology would be referred not
only the enumeration of the flora of the associations, but also more exact
studies as to the importance of the species to the community, and the con-
stancy of the relationship. These relationships are discussed in detail by
PAVILLARD4 in a more recent paper. One phase of this relationship has been
estimated in a quantitative manner by BRAUN-BLANQUET; by giving to each
species in an association a coefficient of affiliation [Gercllachatteteeut), the first
rank (5) being conferred upon species confined exclusively to the particular
association, and the lowest (0) belonging to ubiquists. To this PAVILLARD
adds another evaluation of the species, based upon its importance in develop-

cient, and here also the numerical value is also from 5 too. Analyzed in such
a manner, the floristic composition seems to PaviLtLarpD decidedly the best
manner of characterizing an association. The characterization of the plant
association by floristic composition only is also insisted upon by Du RIETZ .
and associates. They also favor attention to priority in the use of eco-
logical terminology, a concession that ecological writers are not likely to grant.
Du Rrerz contends that the Swedish school of ecologists is distinguished by the
use of true inductive methods as contrasted with the less desirable procedure
of other workers. He also proposes certain new terms of minor importance.
Gams? is less modest in his demands, for he wishes to abolish the use of
formation, association, and most other synecological (or biocoenological) terms
now current, because they have been and still are being employed in different
senses by different writers. Instead of such fairly familiar terms, he would
substitute a new set founded to some extent on new concepts. He contends
that two types of units, the ecological and topographical, have been confused
and should be distinguished with care. The former he calls ‘‘synusia
(associations), and distinguishes three grades where the component elements

- 3Cowtes, H. C., The physiographic ecology of Chicago and vicinity. Bor. Gaz.
31:73-86. 1901.

coigtaen aaa Hi Remarques sur la nomenclature phytogéographique. Mont-
pellier. pp. 27.

5 oe see J., Eine pflanzengeographische Excursion durch Unter-
engadin ae in dem schweizerischen National ‘Park. Bericht. Schw. Bot. Gesells.
26:1-79. 1918.

6 z, C. E., Fries, T. C. E., and Tencwatt, T. A., Vorschlag zur Nomen-
klatur der site kasle hah Pflanzengeographie. Svensk. Bot. Tidskrift 12:145-179-
1918.

7 Gams, H., Prinziprenfragen des Vegetationsforschung. Ein Betrag zur Begrifis-
klarung a Meth odik der Biocoenologie. Vierteljahrschr. Naturf. Gesells. in Zurich
63: 293-493. 1918.

1920] CURRENT LITERATURE 185

of the unit are respectively (1) of the same species, (2) of different species but
of the same growth forms and of similar aspect, and (3) of different species and
various growth forms presenting different series of aspects but united into an
ecological unit in a single habitat by fixed correlation. nig last grade of
synusium corresponds very any with ‘the “‘association” of most authors.
Similar synusia are grouped as “‘isocies.” For the topographical unit he adopts
the word “‘biocoenose” (or biocoenosium), and uses it for the vegetation of a
unit habitat. Biocoenosia me different regions which are compounded of
isocies are called “isocoenosia

The author rejects all Sitecanes: to classify vegetation units upon dynamic
lines. He also gives a new classification of life forms, based largely upon the
RAUNKIAER system, but more extended and including animals. It is safe
to predict that such revolutionary changes as those urged by Gams, even if
they are logically conceived, will not be acceptable to the ecologists of America,
and, judging from the criticism of the scheme by PAVILLARD (1919), they will
meet with no greater favor in France.—Gero. D. FULLER

Statistical methods in ecology.—It seems appropriate that from among
_ the students of that father of modern ecology, EUGENE WARMING, should
come a leader of perhaps a most promising line of advance in the ecology
of today. RAUNKIAER more than any other has opened the way for the
introduction of pees iets | in the study of vegetation. His method

a Statistical method that had been familiar to Danish readers for some years."*

more recent articlé RAUNKIAER® has summarized the material of his

former contributions, and has been able to show something of their applica-
tions to the solution of ecological problems. His statistical or valence meth

consists in determining the relative abundance of the different species compos-

a plant community of definitely limited extent, called by him a “forma-

a. ” although more nearly equivalent to an association as understood by

American ecologists. This determination is made by taking a census of a

* Bor. Gaz. 51:309-310. I91t. 9 Bor. Gaz. 63:242. 1917. ~

Fo , Geo. D., and Bakke, A. L., Raunkiaer’s sone leaf-size classes,
and siedcal shethnds. Plant World 21:25-37, 57-63. fig. ;

™ RAUNKIAER, C., Formations undersgelse og ie: Bot. Tidskr.
30: 20-132. 1909
, Om Velshonsindn. Bot. Tidskr. 34:304-311. 19

———-, Recherches statistiques sur les formations HAE Det. Kgl.

ee Wished dahdices Selskab. Biol. Meddeleser. I 3: pp. 80. figs. 3. 1918.

186 BOTANICAL GAZETTE [FEBRUARY

number (25-50) of small unit areas of the vegetation, selected at random or
according to fixed plans, and outlined by the revolution of a metal radius of
determined length attached to a walking stick.* The convenient size of these
‘unit areas appears to be o.1 sq. m., and the frequency with which a given
species appears in such areas determines its valence, frequency percentage, or
frequency coefficient. Emphasis is placed upon the fact that in an undis-
' turbed area the vegetation will eventually come to a practically complete
equilibrium with the factors of the habitat, and will be composed of the species
of the region best fitted to exist under such conditions. RAUNKIAER therefore
defines his “formation” as “essentially homogeneous from a floristic point of
view,’’ that is, homogeneous as to the dominant species or the species showing
the highest frequency coefficients. Such a statistical: method permits the
quantitative comparison of similar plant communities and their more exact
delimination.

It is interesting to note as the results of the use of such statistical methods,
principally the examination of many plant communities involving the deter-
mination of over 8000 coefficients, that 55 per cent of the species have coeffi-
cients ranging from 1 to 20, 15 per cent from 81 to 100, 14 per cent from 21
to.40, 9 per cent from 61 to 80, and 3 per cent from 41 to 60. In other words,
the least frequent species in the communities studied were most numerous,

author expresses in the form of a law. n a formation in a relative state of
equilibrium what allows one or more species to prosper at the expense of their
neighbors is the fact that the dominant species are better adapted to live under
the conditions existing within the formation of which they are a part and by
pings community life (‘concurrence vitale’) they prevent the other species from
equaling them in frequency. But however well equipped they may be for
such community life, they are not able to preverft other species, widely dis-
seminated but fewer in individuals, from entering the formation and occupying
portions that for any reason whatever may have been left unoccupied by the
dominant species. Thus we see that there is a much larger number of the
least frequent species.’

For the further analysis of peieie RAUNKIAER describes a method of
arriving at the area occupied by each species in the community. This is
accomplished by the study of unit areas similar to those employed in the
determination of frequency; indeed the two could be done simultaneously.
To assist in readily determining the portion of the area occupied by the areal
parts of a species he adds a series of radii of determined length to the one
already affixed at right angles to the walking stick. These are so spaced that
they divide the circular unit area into fifths and tenths, so that by their aid

*3 RAUNKIAER, C., Measuring apparatus for investigations of plant formations.
Bot. Tidskr. 33:45-48. 1912. :

1920] CURRENT LITERATURE 187

the observer is easily able to estimate 10 different degrees of covering. From a
record of the numbers representing these degrees of covering the areal per-
centages. of the different species are readily established.

A summary of the methods employed, and a classification of vegetation
upon the basis of life-forms and leaf-sizes, completes an article rich in sugges-
tions to the ecologist seeking more accurate methods.—GeEo. D. FULLER.

Susceptibility gradients—Following his demonstration of axial’ metabolic

gradients in animals and their relation to the course of development and
individuation, CHILp entered upon a study of axiate plants, particularly
algae. His first paper" on axial gradients in algae appeared several years a,
His interesting and valuable observations’ have been extended to iaciude
a considerable number of new forms, and the results are sufficiently uniform to
warrant the general conclusion that plants and animals are essentially similar
in respect to these axial susceptibility gradients.

Twenty-five species have been studied, 14 of which were considered in the
earlier paper, and all of them show an axial gradient in susceptibility to injury
and death from such agents as KCN, alcohol, ether, HCl, HgCl., CuSO,,
neutral red, temperature, etc. When killing concentrations are used, death

soonest in the most active protoplasm. The susceptibility gradient is
easily altered or reversed by external conditions, by advancing age, physi
logical isolation of cells and branches, and other factors. The ease with which
such reversals occur indicates in some degree the sensitiveness of species.

He finds that the unicellular and seem eas ane — peecer 4 or
unbranched, which occur on some algae
as the main axis. In such forms as Saath and Castagnea, in which the hairs
have basal growth, the : is acropetal; but whenever the hairs grow
apically the normal gradient is basipetal. Reversals may be induced in these
hairs, also, especially with low concentrations of the susceptibility reagents.
In some cases the agent may reverse the susceptibility to itself, or one agent
may reverse the susceptibility to another agent. These results indicate clearly
that hairs represent physiological axes, and the gradient of susceptibility
appears to be one of the aspects of phavundonical polarity in all axes. When
the axial gradients are reversed, these hairs often separate into their component

ssi or the hairs drop from the main axes. Loss of hairs in laboratory material

ses Sees: C. M., Axial susceptibility gradients in algae. Bot. Gaz. 62:89-114.
Ig16.
‘*s ———., Further observations on axial susceptibility gradients in algae. Biol.
Bull. na 7419-440. 1916.
‘———, OF ee gradients in the hairs of certain marine algae. Biol.
ie A 7502.

188 BOTANICAL GAZETTE [FEBRUARY

is undoubtedly associated with reversed gradients brought about by unfavor-
able conditions of confinement.

These changes in gradients of hairs were studied particularly in Griffithsia.”
If conditions are not extreme, obliteration or reversal of the axial gradient is
followed by cell separation, and the death of some of the cells, the death-rate

which are found to arise at the most susceptible end of the old cells. This is
usually the basal end, because the normal gradient had been reversed before
the cells were disconnected. izoids, however, arise only on those parts of
the cell which have the lowest metabolic rates or lowest susceptibility.

The general conclusion of all this work is summarized admirably in the
words of the author: ‘‘The facts support the conclusion that a gradient in
metabolic rate, protoplasmic condition, or whatever we prefer to call it, of
which the susceptibility gradient is within certain limits an indicator, con-
stitutes physiological polarity in protoplasm, and that such a gradient is not
an inherent property of protoplasm, but may be determined and altered by
external factors.

tudents who desire to repeat some of these experiments for themselves
will find a recent paper of interest.’ The axial gradient may be very beauti- —
fully demonstrated colorimetrically by the use of dilute solutions of potassium
permanganate. The protoplasm reduces the permanganate and takes on a
brown color, which appears first and deepest in the most active regions.
Concentrations of M/1000 to M/ 100,000 should be used for such experiments.—

Biology and culture of the higher fungi—Among recent contributions to
our knowledge of this difficult subject is a paper by Boyer”. The first part
deals with attempts at spore germination and culture of over 60 species, and
the second gives in more detail the results of his work with Morchella and
Psaliota.

He recognizes three types of higher fungi: (1) pure saprophytes, (2) facul-
tative parasites, and (3) mycorhizal forms which are constantly associated
with certain trees. Saprophytes, he finds, grow readily on culture media, and
many give rise to carpophores; while many of the mycorhizal group cannot be
grown in pure cultures on any of the many types of media tried. Between
pure saprophytes and forms which will not grow on culture media he finds

7 Curtp, C. M., Experimental axes of the axial gradient in the alga Grifithsia
Bornetiana. Biol. Bull. 32: 213-233. 1917.

8. Demonstration of ie axial gradients by means of potassium perman-
ganate. Biol. Bull. 36:133-147. 1919.

2 Boyer, G., Etudes sur la biologie et la culture des champignons superieurs.
pp. 116. pls. e jigs. 20. Bordeaux. 1918.

#

1920] CURRENT LITERATURE 189

gradations in dependence upon the mycorhizal habit. Some will make only
a very slight mycelial growth in cultures, while others will form abundant
mycelia, but never develop carpophores. Field experiments also confirm this
mycorhizal dependence, but attempts to trace mycelium from carpophore to
tree were seldom successful. He considers the mycorhizal relationship to be
symbiotic, the green plant furnishing carbohydrates and in return receiving
water and salts, especially nitrogenous substances which the fungi probably
obtain by the fixation of free nitrogen.

As a source of cultures he first tried the germination of spores. Various
media and methods of treating spores were tried, but no germinations from
mycorhizal forms such as tubers or amanitas were obtained, and from other
forms the mycelium obtained was seldom vigorous. Because of this he resorted
to the use of portions of the carpophore, flamed over a Bunsen burner,.as a
source of cultures, and found this (which he erroneously considers a new
process) much more satisfactory. In this manner he obtained cultures of 24
species which he describes, giving figures for 17 of them. While many media
were used, he found a devaction from carrots, solidified with gelose (a gum
derived from agar-agar), the most satisfactory. Cultural variations bring into
question the validity of some specific characters, such as size, color, and
characters due to substratum.

In his studies of Morchella cultures were obtained from single spores. The
mycelium was very vigorous, growing well at 10-12° C. Sclerotia o. 5-4 mm.
in diameter appear in 1o-15 days. No conidia or ascocarps were formed.
He attributes the absence of ascocarps either to the limited mycelial growth in
cultures, or, as he considers more probable, to the necessity of a mycorhizal
host prior to ascocarp formation.

Cultures obtained from the spores of Psaliota were always weak, while
those from portions of the carpophore were very vigorous. From his pure
cultures he easily developed successful commercial spawn. Cultures from one
carpophore always developed carpophores with the same varietal characters
as the original, which is a great practical advantage —LEva B. WALKER.

Identification of mahoganies.—To meet the need of some adequate method
for distinguishing the different commercial timbers now classed as mahoganies,
Drxon* has prepared (1) a concise working definition of the term mahogany,
and (2) an anatomical key accompanied by detailed descriptions for the
identification of some of the more common kinds by means of their microscopic
characters. The constant increase in the number of species of mahogany-
yielding trees in economic use, and the doubtful authenticity of many of the
Specimens derived from commercial sources, have made the construction of
such a scheme of classification most difficult.

* Dixon, H. H., Mahogany, the recognition of some of the different kinds by
their microscopic characteristics. Notes from the Bot. School, Trinity College,
Dublin 3:58. pls. 22-54. 1919

Igo BOTANICAL GAZETTE [FEBRUARY

The first part of this preliminary paper discusses the many varied properties
of these different woods, with regard to color, density, hardness, presence or
absence of year-rings, pore-rings, size and contents of vessels, distribution of
parenchyma, etc., and also the numerous contradictory definitions of mahogany
to which these structural differences have given rise. To the general public
and to the majority of woodworkers, mahogany is a reddish wood, generally
with some distinct figure and texture, and valued in proportion to the beauty
of its figure and the resistance of the wood to splitting and warping. Obviously
such a definition is not sufficient. Reddish color and figure, both emphasized
as distinct diagnostics of the original mahogany, Swietenia mahogoni, of course
are essential, as also is the character described as ‘‘roeyness.’’ According to
Drxon, we may recognize as mahogany “all red or red-brown timbers in which
the fibers of the adjacent layers cross each other obliquely, and so give rise to
a play of light and shade on longitudinal surfaces (‘roe’), greatly emphasizing
the figure and conferring on the wood a freedom from splitting and warping. i:
In addition, a mahogany should have scattered vessels, isolated or in small
radial groups; the circumvasal parenchyma should be thin, and the medullary
rays not more than 9 cells in width and under 2 mm. in height. In other
respects the different woods designated by this name exhibit great structural
variability.

The second part of the article presents the key and well written anatomical
diagnoses of Western, African, Asiatic, and Australasian mahoganies. The
23 plates are from photomicrographs of transverse, radial, and tangential sec-
tions of the various woods, and are intended to show their distinct micro-
scopic features—LADemMa M. Lancpon.

Comparative salt absorption.—St1LEs and Kipp” have published two papers
on the mechanism of salt absorption by disks of carrots and of potato tubers.
Their method of study was to immerse a quantity of uniform disks of the
material in salt solutions, and follow the course of absorption by the changes
in the electrical conductivity. Although the conductivity is affected, not
only by absorption of salt, but also by exosmosis, the writers believe that the
latter is small, especially in the case of carrot. Potassium, sodium, and
calcium chlorides are readily absorbed in all concentrations from N/1o to
N/s000. The initial rate of absorption is roughly proportional to the con-
centration, but after a time this does not hold. The ratio of final internal
concentration (arrived at by calculation) to final external concentration they
call the absorption ratio. With low external concentrations this ratio is many

21 Stites, W.,and Kup, F., The influence of l ti the position
of the equilbitum attained in the intake of salts be plant cells. Proc. Roy. Soc.
B 90:448-470. 1919.

Se ae parative rate of absorption of various salts by plant tissue.
Proc. Roy. Soc. B g0:487-504. 1919.

1920] CURRENT LITERATURE Ig!

times unity, but with higher concentrations it becomes considerably less than
unity. Although this relation can be expressed by the adsorption formula
nd m

are constants), the writers do not feel the data es the conclusion that
absorption of these salts is an adsorption phenome

Kations are absorbed initially in the order K, Ca, Na], Li, [Mg,; Zn], Al;
as equilibrium is approached the order is K, Na, Li, [Ca a, Mg]. The initial
order for ve anions is SO, NO,, Cl; the final order, NO, Cl, SO,. “Although

concerning the method of estimating the osmotic pressure of sap by the swelling
or shrinkage of the tissue when immersed in salt solutions. Using sections of
the root of the red beet, they found that they neither gained nor lost in weight
in 0.40 N NaCl, and that this concentration was also just insufficient to cause

plasmolysis. The writers therefore maintain that this concentration is
approximately isotonic with the beet root sap.—J. J. WILLAMAN.

Tyrosin in fungi—DopcE* reports some fee RE on the chemistry
of the tyrosinase reaction in the fungi which turn blue or black on exposure
to air. The fungi were sliced, dried, and then ground into a flour, and this
fungus flour used in the investigation. ‘In the work with tyrosin, the dried
fungus flour was added directly to the substrate, toluol added, and the mixture
left to extract the enzym and the enzym to react with the tyrosin.” The
author studied the reactions with the amino, carboxyl, and phenol groups. A
modified form of the “micro” VAN SLYKE apparatus was used for the determi-
nation of the amino nitrogen, the permutite method of Forrn and BELL for
the determination of ammonia, and the colorimeter method of Duccar and
Donce for the determination of the carboxyl and phenol groups.

The following conclusions are drawn from these investigations: “(1) that
the tyrosinase reaction is not a deamination, although it is possible that
deaminases may exist in the same organism with tyrosinase; (2) that the
tyrosin molecule is synthesized into a larger, more complex molecule, in which
part of the carboxyl groups is either split off as carbon dioxide, or more proba-
bly bound in the molecule so that it will not react with alkali.” —J. Wooparp.

* STILES, W., and JORGENSEN, W., On the relation of eee to the shrinkage

of plant tissue in salt solutions. New Phytol. 18:40-5o.
Donce, C, W., Tyrosin in me fungi: chemistry a dak of studying the
tyrosinase reaction, ok Mo. t. Gard. 6: 71-92. 1919.

12:4 BOTANICAL GAZETTE [FEBRUARY

Cytology of gigantism.—The relation between the nuclei, and particularly
the chromosomes, of exceptionally large individuals or varieties of a species
has been described in several cases. TISCHLER* secured a giant form of

number of chromosomes, as in some forms of Oenothera, Primula, and Solanum.
The relation between chromosomes and dwarfing has received little
attention from botanists, but the cytology of Oenothera Lamarckiana vat.
nanella, as described by Gates, and some observations by zoologists, indicate
that the dwarfing is correlated, sometimes with a decrease in the number of
chromosomes, and sometimes with a diminution in their size, without any
change in their number.—C. J. CHAMBERLAIN.

Ecology of fossil plants——In a report upon some fossil plant material
found in the gorge of the Columbia River,in Oregon and Washington, CHANEY®
notes that some 80 species are represented, 75 of which are angiosperms, of
which 2 only are monocotyledons. A list of the genera with the number of
species in each includes: Ginkgo 1, Pinus 1, Smilax 1, Cyperacites 2, Populus 3,
Salix 3, Hicoria 2, Juglans 1, Anis r, Carpiesi 1, Corylus 1, Castanea 1,
Quercus 12, Ulmus 2, Prise 2, M anil I, Lonrus 2, Platanus 2, Liqui-
dambar 3, Crataegus 1, Sterculia 1, Rhus 1, Ilex 1, Acer 3, and Fraxinus 1.
From a study of this material the author cousindes: that the climate indicated
by this Eagle Creek flora appears to have been somewhat warmer and drier
than at present. The length of the epoch is to be placed at thousands rather
than at scores of years. The dominant plants point to the existence of two
habitats, one xerophytic and the other mesophytic. An area of upland dis-
sected by a valley furnishes such habitats, and at the same time meets the
geological requirements of the formation.—Gro. D. FULLER.

4 TISCHLER, G., Untersuchungen iiber den Riesenwuchs von Phragmites communis
var. Pseudodonax. Ber. Deutsch. Bot. Gesells. 36:549-558. pl. 17. 1918.

*s CHANEY, R. W., The ecological significance of the Eagle Creek flora of the
Columbia River gorge. Jour. Geol. 26:577-592. figs. 3. 1918.

VOLUME LXIx NUMBER 3

THE
BOTANICAL GAZETTE

MARCH 1920

SHORT CYCLE UROMYCES OF NORTH AMERICA!
G. R. Brissy
(WITH PLATE x)

The short cycle Uromyces may be segregated as a group by utiliz-
ing the criteria of life cycle and character of teliospores. Aside
from any question of the validity of such bases for segregation, it
is evident that it is a common practice thus to set apart this group,
and that an opportunity is thereby afforded to consider relationships
of such rusts to each other and to other rusts.

The short cycle Uromyces are of considerable interest, although
as yet comparatively few species or even collections are recorded
for North America. These rusts occur over a wide geographical
range, however, and are parasitic upon widely separated families
of hosts

The mites has been privileged to examine the excellent collec-
tion of short cycle Uromyces in the herbarium of Dr. J. C. ARTHUR.
This paper represents the results of the study of the group as made
primarily for the North American Flora, but is presented separately
in order to give notes and discussions not permissible in that
publication.

* Abstract submitted before American Phytopathological Society at the New
York meeti ing, and published in Phytopathology 7:74. 1917. ‘ Contribution from
Botanical Department of Purdue University Agricultural Experiment Station

193

194 BOTANICAL GAZETTE [MARCH

Characters and relationships

The rusts considered in this paper are those which fulfil the
following requirements:

Cycle of development includes only pycnia (sometimes) and telia, both
subepidermal.

Pycnia deep-seated, globose or flask-shaped, with ostiolar filaments.

Telia erumpent, usually grouped; teliospores free, pediceled, 1-celled;
wall firm, colored, smooth or variously sculptured; germination by a single
promycelium from an apical pore

Urediniospores normally sisent but occasionally found in the telia.

The association of pycnia with telia has for some time been con-
sidered the criterion of short cycle rust (1, 4). The occurrence of
definite aecia or uredinia (providing the evidence indicates that the
aecia or uredinia belong with the telial stage present) suffices to
exclude a specimen from the group under consideration. While
some suspicion may be aroused by the presence of urediniospores,
such spores occasionally occur in the telia. In the cases in which
pycnia are only rarely or not at all produced, telia only being
present, the arrangement and character of the telia usually may be
utilized to indicate whether or not the specimen is short cycled;
a grouping of the telia,in definite circinating or crowded groups,
or the occurrence of germination of the teliospores at or soon after
maturity, usually means that such a specimen belongs with the
group of rusts here treated. In certain cases, however, the telia
are diffused, and other considerations must be brought to bear.

A study of the Uromyces forms of the rusts as represented in
the Arthur herbarium and of the literature indicates that, in North
America, only the 11 species described are at present known to
belong in reality to short cycle forms.

Dre£TEL (10) pointed out that the percentage of endemic species
of rusts is higher in proportion to the isolation of the geographical
region; that Uromyces shows a higher percentage of species in
warmer than in colder regions;. and that in both the Old and the
New World the number of species of Uromyces is about one-third
that of the number of species of Puccinia. It is to be noted that, so
far as known, 8 of the 11 short cycle species of Uromyces are endemic
to North America, and only 1 of the 11 species occurs also in Europe.

1920] BISBY—UROMYCES 195

These forms are more especially found in the warmer parts of the
continent, just as all Uromyces seem to be more numerous in warmer
regions. While in North America some three times as many species
of Puccinia as of Uromyces exist, the relation of the forms when
divided according to their life cycle is strikingly different; for about
140 short cycle species of Puccinia are known for North America,
in contrast to these 11 species of Uromyces.

P. and H. Sypow (25), in their monograph of Uromyces, de-
scribed only the telial stage for 183 of the 504 species considered in
that work. For only a very few of these, however, were pycnia
described. When full information is in hand, a large number of
the 183 forms will of course be found not to be short cycled. It
appears, however, that a comparatively greater preponderance of ~
these short cycle forms of Uromyces may be found in the more
tropical regions. The observation of MAGNus (17) and of FISCHER
(15), that increased altitude results in shortened life cycles for the
rusts, is somewhat borne out by the fact that certain short cycle
Uromyces are limited to the Rocky Mountain region. The effect
of altitude and temperature can be better noted with the more
numerous short cycle species of Puccinia.

OrtTON (21) has touched upon the relation of a group of rusts
with a common life cycle, opsis forms of Puccinia (the genus
Allodus), to other groups with different life cycles. Comparable
relationships and correlations with other rusts are to be noted
with the group of rusts considered in this paper; some attention
is directed to these points with the discussion of the several species.
The rust in its development is intimately dependent upon its host.
FiscHER (13) in 1898 emphasized the similarity between the
teliospores of certain short cycle rusts and of long cycle heteroecious
rusts whose aecia occurred upon the host of the short cycle form.
He considered that this similarity indicated a phylogenetic rela~
tionship between such rusts with different life cycles. Dreret (9)
‘considered that the Uredinales have probably developed during
geological times along with their hosts. ARTHUR (5) has pointed
out that the relationships of the rusts often reflect the relationships
of the hosts upon which they occur. The writer (6) has also dealt
somewhat with this point. :

196 BOTANICAL GAZETTE [MARCH

DierTet (11) considered that Uromyces is. the most primitive
of the Pucciniaceae, both on account of the possession of 1-celled
teliospores, and because it occurs upon such diverse families of ©
monocotyledons and dicotyledons. Whether long cycle or short
cycle rusts are more primitive is still a mooted question.

The existence of species of these rusts as lepto-forms or micro-
forms, that is, whether or not the teliospores germinate upon
maturity, while subject somewhat to seasonal variation, is a fairly
constant and characteristic feature with each species.

Life history; cytology

The life cycle is simplified in a short cycle species to the extent
' that only telia, often with pycnia, are produced. The occasional
occurrence of a few urediniospores in the telia is a phenomenon in
common with other erups of rusts which ordinarily do not bear
such spores.

FISCHER (12) first cultured a short cycle Uromyces. He sowed
teliospores of U. Cacaliae (DC.) Unger upon Adenostyles alpina
Kern, securing telia again without the intervention of any other
spore stages. No trace of pycnia wasfound. In 1905 FISCHER (14)
reported the culture of the short cycle species of Uromyces which
occurs in Europe as well as in America, U. Solidaginis. He sowed
teliospores upon Solidago Virgaurea alpestris, and in about 13 days
noted the infection upon the leaves; telia were produced, but in no
case were pycnia to be observed. While North American material
of this species has not been cultured, it is supposed that similar
conditions obtain here. ScHNEMER (24) cultured U. Scillarum
(Grev.) Wint., a short cycle form, and reported specialization as to
hosts. The teliospores were found to be capable of germination,
either at once or after a period of rest) No cultures of endemic
North American short cycle Uromyces seem to have been reported.
Carteton (8), ARTHUR (3), and others, however, have reported
cultures of some species of lepto-Puccinia. Wu1LLE (27) recently
found a sharp specialization of the lepto-form Puccinia Arenariae
upon the different host genera attacked.

The evidence obtained from cultures indicates that similar con-
ditions exist in the short cycle forms, both of Uromyces and Puccinia.

1920] BISBY—UROMYCES 197

A greater specialization and fixity may exist with short cycle forms
_ than with forms with long life cycles; of course fewer spore forms
upon which variability may be manifested are present.

_Pycnia may be produced, under certain conditions, in some
of these short cycle species of Uromyces not yet known to produce '
pycnia. It is to_be noted, however, that species in which the telio-
spores germinate at maturity, that is, lepto-forms, seldom produce
pycnia. ‘Teliospores cannot function directly as repeating spores,
but in lepto-forms a comparatively rapid repetition is secured
through the intervention of the basidiospores, which are produced
immediately upon maturity of the teliospores.

Cytological work upon the short cycle rusts indicates that similar
conditions obtain with the short cycle species, both of Uromyces
and Puccinia. The work of SAppIN-TROUFFY (23) upon the his-
tology of the rusts included a study of the short cycle forms Uro-
myces Ficariae (Schum.) Lev. and Puccinia malvacearum Mont.
His observations were corroborated and extended with the two rusts,
among others, by BLACKMAN and FRASER (7). They found that
the general vegetative mycelium of Uromyces Ficariae consists
of uninucleate cells, some of the later vegetative, together with
the sori-forming, mycelium being binucleate. They found similar
conditions for Puccinia malvacearum, the binucleate condition
evidently arising at several different points for each sorus, shortly
before the sorus is formed. BLACKMAN and FRaseER also observed
that the short cycle forms Puccinia Adoxae Hedw.f. and Uromyces
Scillarum (Grev.) Wint. had a binucleate rather than a uninucleate
general vegetative mycelium, and suggested that it is “probable

that in these two forms the conjugate condition is produced soon
after infection by nuclear migration, or by cell fusion, between
vegetative cells.” OLivE (20) discussed and figured sexual fusions
near the base of the telium in a short cycle form, Puccinia trans-
formans Ellis and Ey. Dealing with North American rusts,
OLIVE (19) also reported that differing conditions as to the sporo-
phytic and gametophytic generations occurred with certain short
cycle Puccinia forms; while U romyces Rudbeckiae Arth. and Holw.
Showed the anomalous extreme of possessing uninucleate cells
_through all the mycelium and sorus, even including the teliospores.

198 BOTANICAL GAZETTE [MARCH

This phenomenon he was not able to explain fully. Other papers
to be noted are those by WERTH and Lupwics (26), HorrMAN (16),
and Moreau (18). A considerable summary of recent cytological
work is presented by RAMSBOTTOM (22).

From this work it appears that the duration of the binucleate
stage varies in different species of short cycle rusts, being brief,
extended, or intermediate. Fusions between cells initiate this
binucleate condition. Some life history problems, including the

TABLE I Re
HOST RELATIONSHIPS OF SHORT CYCLE JU; romyces
y Common
Species of Fight ere 4 a
Host - Distribution Mycelium condition of Pycnia
Uromyces germination

Liliaceae

Erythronium...| U. heterodermus| Rockies Local or rather diffuse} Micro Present
Cassiaceae

Bauhinia....... U. bauhiniicola | S.W. Mexico Rather diffuse Micro Present

Bauhinia....... U. jamaicensis Mexico; West Indies | Local Micro Present
Fabaceae

Paoralea... 3... U.abbreviatus | Pacific Coast Local, becoming Micro Present

: rather diffuse

Euphorbiaceae ‘

Teacsyce| ..| U. Tranzschelii_| Western N.A. Diffuse ~ | Micro Present
Primulaceae

Primula: 05.5. U. nevadensis Western N.A. Local or rather diffuse} Micro Not known
Myrsinaceae :

Myrsines....... U. Myrsines Costa Rica; S.A. Local Micro Not known
Carduaceae :

Solidago. ...... U. Solidaginis W.N.A.; Europe Local Micro Not known

Anaphalis...... U. amoenus Western N.A. Local Micro Not known

Rudbeckia..... U. Rudbeckiae | Central N.A. Local Lepto Not known

Bidens. 3555. 3. U. Bidentis Porto Rico; S.A. Local Lepto Not known

relative importance and relation of cell and nuclear fusions, some
relations in the formation of pycnia in short cycle forms, the
presence of perennial mycelium, etc., appear not to have been fully
determined.
Hosts

The range of hosts attacked by these North American short
cycle species of Uromyces embraces both the monocotyledons and
dicotyledons. The situation is shown in table I.

Foreign species of short cycle Uromyces fill in several families
not represented here. The wide range of hosts attacked indicates
that these rusts do not form a restricted group; one might expect

1920] BISBY—UROMYCES 199

to find affiliations with other forms of rusts upon the same or similar
hosts through the various families, and such is the case. Under
the species U. heterodermus a considerable comparison with rusts
from related hosts is made, suggesting that certain groups of hosts
appear to harbor rusts characterized by various definite morpho-
logical characters.

The geographical distribution of North American short cycle
species of Uromyces would indicate further that the mountainous
and more tropical regions furnish the most favorable location for
these forms. Only U. Rudbeckiae has a comparatively wide range,
a range including the plains area.

Whether or not it is more than a coincidence that the absence
of pycnia and the occurrence of lepto-germination are found on
hosts higher in the evolutionary scale, the writer is not prepared
to say.

Taxonomic

With the progress of critical studies of North American rusts,
other short cycle forms will undoubtedly be separated out, and
further evidence secured as to the fixity and definiteness of the
life cycle in certain of these rusts. Uromyces heterodermus, for
example, was long placed with U. Erythronii, a correlated form.
It was found also that U. Bidentis was a short cycle form which
resembled U. bidenticola (P. Henn.) Arth. so far as characters of
teliospores are concerned. It is no doubt true that other short
cycle forms have been collected and placed with correlated long
cycle forms, although cultures are needed to determine the life cycle
in certain cases.

« The rr species of Uromyces sonnideeel have several points of
similarity, one of which is the fact that all possess teliospores with
apices more or less thickened. In none of the species were para-
physes, stromata, isolated peridial cells, or other accompanying
_ Structures found in the telia.
Key

Teliospores verrucose.

Teli -

apy oo Py thic y mie eR Dery ce oeeies « 1. U. heterodermus
MAD Gp too. 6p thick) co. 735054 soc ale
Telidspores short, Ul 6 40 Mi 5 ik sa ees ..ees 5. U. Transschelis

200 BOTANICAL GAZETTE [MARCH .

Teliospores reticulate.
ONE CA 25 OY 1 96 isk sh Se So sees 2. U. bauhiniicola
RE SPF 102s ae eh en we SE 3. U. jamaicensis
Teliospores smooth.
all thin, 1-1.5 uw.
Spores narrow, 11-17 pw wide.

SOROS BIA ie ON a es i 7. U. Myrsines
SDOTES 16~-39- 1OE es a Fs 10. U. Rudbeckiae
Spores broad, 15-28: 4 wide... 2.5 i chi ence 11. U. Bidentis .
Wall thick, 1. 5-3 uw.
Fee Ue 00 gs rs sees ch ve es 8. U. Solidaginis
Apex thickened 3-7 uy.
ices 99-0 b On ck is co ee 4. U. abbreviatus
Spores 19-30 ML Mi a es g. U. amoenus

1. UROMYCES HETERODERMUS Sydow, Ann. Myc. 4:29. 1906.

O. Pycnia amphigenous, not uncommon, gregarious in loose
groups with the telia, o.5-1.5 mm. across, inconspicuous, subepi-
dermal, dark golden-brown, flattened globoid, 100-185 y in diameter
by 65-130 win height; ostiolar filaments few, loose, up to 65 u long.

III. Telia amphigenous, numerous, scattered or in small groups,
sometimes upon inconspicuous spots, roundish or oval, o.3-2 mm.
across, rather early naked, pulverulent, dark cinnamon-brown,
surrounding epidermis noticeable; teliospores ellipsoid or broadly
ellipsoid, 19-26 26-43 w, rounded above, rounded or slightly
narrowed below; wall dark golden-brown, 1.5 u thick, thickened
at the apex with a distinct hyaline papilla, 3-6 uw, coarsely verrucose
above, with the markings often in longitudinal ridges, smoother
below; pedicel hyaline, fragile, short.

On wiiaceaE: Erythronium grandiflorum Pursh, Colorado, Montana,
Utah, Washington, British Columbia; E. montanum S. Wats., Washington;
E. obtusatum Goodding, Wyoming; E. parviflorum (Wats.) Goodding (E. grandi-
florum parviflorum S. Wats.), Colorado, Montana, Oregon, Utah, Washington,
Wyoming.

TYPE LOCALITY: Wasatch Mountains, Utah, on Erythronium parviflorum.

DistriBuTiIon: Rocky Mountain region from Colorado and Utah north-
ward, and to the coast in Oregon.

Exsiccati: Barth., Fungi Columb. 4694; Barth., N.Am. Ured. 789, 1592;
1692; Garrett, Fungi Utah. 178; Ellis and Ev., Fungi Columb. 750.

LITERATURE: Sypow, Monog. Ured. 2:270. 1910; SACCARDO, Syll. Fung.
ar?S70. 10t¢.

1920] BISBY—UROMYCES 201

This rust, previous to Sypow’s description in 1906, passed as
U. Erythronii (DC.) Pass., a related European species possessing
aecia. Thus Erris and EverHart’s Fungi Columbiani 750 was
issued as U. Erythronii. The host of this collection is undoubtedly
Erythronium parviflorum; earlier collections of this host were fre-
quently considered, as in this case, to be E. grandiflorum.

This rust occurs upon the species of Erythronium found in the
western part of North America. According to ENGLER (ENGLER
and PRANTL, Nat. Pflanz. 25:60. 1888) species of Erythronium
occur particularly in North America. He places the following
genera together to constitute the section Liloideae-Tulipeae: Lilium,
Fritillaria, Erythronium, Tulipa, Lloydia, and Calochortus. Several
rusts occur upon these genera of hosts. ' For the sake of comparison,
all such rusts are tabulated. To avoid a personal factor, the data
are largely from the Sypows’ Monograph, and any supplementary
data obtained are added in brackets. Parentheses indicate a rather
free translation. Some data are taken from a paper by REEs
(Amer. Jour. Bot. 4:368-373. 1917), who also presents drawings
which support the contention that the rusts on these hosts possess
rather unusual morphological similarities.

Table II shows many points of similarity i in these rusts. It is
_ to be noted that practically all possess amphigenous, rounded or
minute, pulverulent sori, with spores broadly ellipsoid, rather
similar as to size, with the wall usually moderately thick, apex
somewhat thickened with a papilla, pedicel hyaline and short;
and especially, all possess, in a striking manner, surface markings
usually striate or verrucose and arranged in rows. This unanimity
in morphological characters would indicate that a closely and defi-
nitely related group of rusts occurs upon these related hosts.
Correlations, more or less perfect, obtain throughout this group
of rusts upon the Liloideae-Tulipeae, and are found to extend
further through the Liliaceae. Figs. 1-6 illustrate, for comparison,
the teliospores of three of these rusts.

2. UROMYCES BAUHINIICOLA Arth. Bor. Gaz. 39:389. 1905.—
Telospora Bauhiniicola Arth., Result. Sci. Congr. Bot. Vienne 346.
1906

BOTANICAL GAZETTE [MARCH

202

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Il TIavi

1920] BISBY—UROMYCES 203

O. Pycnia epiphyllous, few, gregarious in small groups, usually
opposite the telia, punctiform, subepidermal, brownish, flattened
globose, 60-1304 in diameter by 30-65 u in. height; ostiolar
filaments compact, short.

III. Telia at first hypophyllous, becoming also somewhat epi-
phyllous, numerous, scattered or in small groups, roundish, small,
o.2-Imm. across, early naked, pulverulent, chocolate-brown,
surrounding epidermis inconspicuous; teliospores globoid or broadly
ellipsoid, 14-21 by 18-26 pw, rounded at the ends; wall cinnamon
or chestnut brown, thick, 2.5—4 wu, apex thicker, 4—7 u, with a paler,
broad umbo, finely reticulated; pedicel pale or colorless, often
roughened below, rather fragile but sometimes two or three times
as long as the spore. “i

On CasstaceaE: Bauhinia Pringlei S. Wats., Jalisco; Bauhinia sp.,
Guerrero.

TYPE LocaLity: Guadalajara, Mexico, on Bauhinia Pringlei.

DIstTRIBUTION: Known only from Southwest Central Mexico.

Intustration: Ark. Bot. Stockh. 4: $l. r. fig. 9.

Exsiccati: Barth., N.Am. Ured. 286.

LITERATURE: VESTERGREN, Ark. Bot. Stockh. 4:28-29. 1905; SyDOw,
Monog. Ured. 2:80, 81. 1909; SACCARDO, Syll. Fung. 21:550-551. 1912.

3. UROMYCES JAMAICENSIS Vesterg. Ark. Bot. Stockh. 4:33.
1905.

O. Pycnia chiefly epiphyllous, gregarious in small groups with

the telia, subepidermal, brownish, flattened, 60-100 » in diameter
by 45-70 uw in height; ostiolar filaments compact, a extending
beyond the ostioles.

III. Telia amphigenous, numerous, gregarious in small groups
or occurring singly, sometimes on small yellowish spots, roundish,
small, o.1-1 mm. across, early naked, pulverulent, chestnut-brown,
surrounding epidermis noticeable; teliospores globoid, broadly
ellipsoid or obovoid, 12~17 X 16-23 mu, rounded or slightly narrowed
at the ends; wall cinnamon-brown, 1 .5—2 u (sometimes up to 3.5 y)
thick, thicker at the apex, up to 5 4, with a lighter crater or cap-
shaped crown, closely and finely reticulate, appearing verrucose
under the lower powers of the microscope; eres pale, fragile,
4-15 uw long,

204 BOTANICAL GAZETTE [MARCH

On CASSIACEAE: Bauhinia ngees oe Cuba, Guanajuoto; B. Pauletia
Pers., Porto Rico; B. porrecta Sw., Jam

TYPE LOCALITY: Constant Sorte Wess on Bauhinia sp.

DISTRIBUTION: Mexico and the West Indies.

ILLUSTRATION: Ark. Bot. Stockh. 4: pl. 2. fig. 14

LITERATURE: Sypow, Monog. Ured. 2: 184. 1909; . SACcARDO, Syll. Fung.
212552-553- Ig12.

This species may perhaps be distinguished from the preceding
by the somewhat reduced length and breadth of the teliospores,
the wall thickness often being less also. The differences described
- by VESTERGREN (loc. cit.) have not been found to hold entirely
throughout the collections at the Arthur herbarium. Some differ-
ences, however, are still to be found between the two species of rust,
and they are maintained as separate species, at least pending
further collections.

VESTERGREN’S supposition that Uromyces jamaicensis is a
micro-Uromyces has been corroborated by the discovery of pycnia
associated with telia upon a Cuban specimen of Bauhinia divaricata.
The specimen upon B. porrecta collected by THAXTER has not been
seen, but VESTERGREN’S type collection has been examined.

VESTERGREN separated 17 species of Uromyces upon the host
Bauhinia, for none of which aecia are known. Evident similarities
are shown between the species as he described and figured them.
Uromyces only are known to occur upon Bauhinia. Many species
of Bauhinia occur in the tropics; related genera, as shown by
ENGLER and Prant1’s classification, are chiefly genera upon which
rusts have not yet been found. The reticulate nature of the
sculpturing upon the surface of the teliospores of these two species
is minute, but evident under higher microscopic power. Figs. 7-10
illustrate the two species.

4. UROMYCES ABBREVIATUS Arth. Bull. Torr. Bot. Club 42:587.
IQI5.

O. Pycnia hypophyllous; scattered among the telia, inconspicu-
ous, subepidermal, deep seated, dark honey-yellow, globose or
flattened globose, 115-200 uw in diameter by 95~-140 pu in height;
ostiolar filaments dense, often falling away, up to 60 p in length.

III. Telia hypophyllous, rarely also epiphyllous, densely
clustered, becoming scattered over considerable areas, roundish,

1920] BISBY—UROMYCES 205

©.2-0.7 mm. across, early naked, pulverulent, chocolate-brown,
surrounding epidermis at first evident, later often hidden by the
loose spores; teliospores ellipsoid or irregularly obovoid, 21-26 X
27-40 w (sometimes variable in size, and larger), roundéd above,
rounded or narrowed below; wall chestnut-brown, 1. 5-3 uw thick,
apex 3-5 u thick, often with a slight umbo over the pore, smooth;
pedicel colorless, delicate, fugacious, half as long as the spore or
ess.

On FA ABACEAE: Psoralea physodes Dougl., California, Washington, British
Columbia; P. Purshii Vail, Nevada.

TYPE LOCALITY: Winnemucca, Nevada, on Psoralea Purshii.

DISTRIBUTION: Pacific Coast region, west of the mountains, from British
Columbia to California.

Exsiccati: Barth., N.Am. Ured. 1582; D. Griff., W.Am. Fungi 390;
Barth., Fungi Cohan: 4884.

The type of this species is GrirFITH’s West American Fungi
390, which was issued as Uromyces Psoraleae Peck. U. Psoraleae
possesses aecia, however. U. abbreviatus, while without aecia,
and possessing pycnia with the telia, resembles U. Psoraleae in the
telial stage, as indicated by ARTHUR in the notes with the original
description. While U. Psoraleae extends to the Pacific Coast, it
is more common in the Rocky Mountain region, and extends over
the plains to the east of the mountains. U. abbreviatus, so far as
known, is limited to the region west of the Rockies.

bers is an unconnected Aecidium (Aecidium onobrychidis
Burrill, Bull. Ill. State Lab. Nat. Hist..2:225. 1885) upon Psoralea
Onobrychis, represented as far as known by the one collection by
SEYMOUR in Illinois, and distributed by ELtis and EvERHART as
North American Fungi 1826. No other species of rust are reported
for the genus Psoralea, and these species are only known in North
America. Related hosts, as given by ENGLER and PRANTL, except
for the genus Indigofera in an adjoining section, are scarcely known
to be attacked by rusts; no closely related rusts are evident upon
related hosts.

While the type collection is from an altitude of about 5000 ft.,
other collections in the Arthur herbarium are from nearer the coast,
at much less altitude, extending almost down to sea-level.

206 BOTANICAL GAZETTE [MARCH

5. Uromyces TRANZSCHELIT Sydow; Tranzschel, Ann. Myc.
8:20. IgI0.

O. Pycnia hypophyllous, scattered among the telia, or in groups,
noticeable, subepidermal, dark yellow, globoid or flask-shaped,
100-145 » in diameter by 75~130 u in height; ostiolar filaments
dense, agglutinated into a-truncate column, 50-80» in height,
50-70 pw in diameter at the ostiole.

III. Telia hypophyllous, occasionally sparingly epiphyllous,
numerous, evenly scattered over large areas, or sometimes in groups
around the pycnia, roundish, o.2—o.6 mm. across, early naked by a
central pore, pulverulent, chestnut-brown, surrounding epidermis
crateriform, conspicuous; teliospores globoid or ellipsoid, 15-22
19-30 w, rounded at the ends, wall cinnamon-brown, 1I.5-2.5 #
thick, apex 3-5 uw thick with a low, sub-hyaline apiculus, minutely
verrucose, the markings often in irregular longitudinal lines;
pedicel colorless, deciduous.

On EvpPHORBIACEAE: Chamaesyce serpens (H.B.K.) Small (Euphorbia
serpens H.B.K.), California; Tithymalus montanus (Engelm.) Small (Euphorbia
montana Engelm.), Colorado, New Mexico, Utah, Wyoming; 7. robustus

Wyoming; Tithymalus sp. (Euphorbia Palmeri Engelm.), Lower California.

TYPE LOCALITY: Colorado, on Euphorbia montana.

DIsTRIBUTION: From Wyoming to New Mexico, California, and Lower
California.

Exsiccatt: Barth., N.Am. Ured. 499; Ellis and Ev., Fungi Columb. 1069;
Ellis and Ev., N.Am. Buiigi 2230; Garrett, Fungi Utah. 97.

Lisa scunk: TRANZSCHEL, Ann. Myc. 8:1-35. 1910; Sypow, Monog.
Ured. 2:171-172. 1910; Saccarpo, Syll. Fung. 21:560-561. 1912; DIETEL,
Hedw. 28:185-187. 1889; ARTHUR, Bull. Torr. Bot. Club 45:152. 1918.

This rust passed as Uromyces scutellatus (Schrank.) Lev., a
European species, until Sypow’s description in 1910. -TRANZSCHEL
pointed out that U. Tranzschelii is similar to U. monspessulanus
Tranz.; indeed, other similarities to various Euphorbiaceous rusts
are evident. In his study of the autoecious rusts upon Euphorbia,
TRANZSCHEL stated that most European autoecious species with
telia from diffused mycelium had passed as two species, Uromyces
scutellatus or U. excavatus; he divided such forms into some 12
species, and found a total of 27 autoecious species of Uromyces

1920] BISBY—UROMYCES 207

upon hosts belonging to the various sections of the genus Euphorbia.
That these species are related is evidenced by the fact that many
had passed under one name; furthermore, many similarities are to
be noted from TRANZSCHEL’s descriptions. For example, all but
one species are listed as having verrucose or striolate teliospore
walls. A table showing characters in a manner similar to those
tabulated under U. heterodermus would be illuminating as indicating
relationships between U. Tranzschelii and other species of rust upon
related hosts. The writer considered it sufficient, however, to
call attention to TRANZSCHEL’s work as indicating relationships.
Certain heteroecious species with aecia upon Euphorbia likewise
show resemblances to U. Tranzschelit.

Both Erxis and Evernart’s Fungi Columbiani 1069 and North
American Fungi 2230 were issued as U. scutellatus, while GARRETT’S
Fungi Utahensis g7 was issued as U. andinus P. Magn., a related
South American rust.

The range of U. Tranzschelii begins at about the western
limit of the range of the related species U. proeminens (DC.) Pass.,
and continues westward to the Pacific Coast. Range conditions
comparable with those of U. abbreviatus are thus shown, and neither
of these short cycle forms necessarily occurs at high altitudes.

TRANZSCHEL (loc. cit., p. 20) considered the rust upon Euphorbia
Palmeri to be different, apparently another species. The specimen
| studied by the writer is not considered different from other
specimens of U. Tranzschelii.

DieTeL (loc. cit.) commented upon Ettis and EvERHART’S
North American Fungi 2230, especially concerning the relationship
of an Aecidium upon the same host distributed as no. 2215 of the
Same exsiccati. It is true that Aecidium Tithymali Arth. occurs
upon the same hosts, sometimes upon the same leaves, as Uromyces
Tranzschelii. The situation in regard to this Aecidium Tithymali
is uncertain. Germination tests show that.it is a true Aecidium
and not an Endophyllum. Its alternate host, however, has not
been found. Arruur (loc. cit.) has discussed this Aecidium and
its possible relation to U. Tranzschelii.

6. UROMYCES NEVADENSIS Hark. Bull. Calif. Acad. Sci. 1:36.
1884.—Cacomurus nevadensis Kuntze, Rev. Gen. 33:450. 1898.

208 BOTANICAL GAZETTE [MARCH

O. Pycnia unknown.

III. Telia amphigenous, circinating in groups 2-5 mm. across, ,
or somewhat scattered, round or oval, o.2-1.0 mm. across, early
naked, pulvinate, becoming somewhat pulverulent, chestnut-
brown, ruptured epidermis conspicuous; teliospores oblong, oblong-
obovoid, or ellipsoid, 19-27 X 29-47 w, rounded at the apex, rounded
or narrowed toward the base; wall cinnamon-brown, lighter or
colorless at the apex, moderately thick, 1 .5—-2.5 u, thickened at the
apex, 5-7, moderately and rather finely verrucose; pedicel
colorless, fragile.

On PRIMULACEAE: Primula suffrutescens Gray, Nevada.

TYPE LOCALITY: Lake Tahoe, Nevada, on P. suffrutescens.
DISTRIBUTION: Known only from the type locality.

LITERATURE: Macnus, Ber. Deutsch. Bot. Gesells. '18:451-459. 1900.
ILLUSTRATION: MaAcnus, loc. cit. pl. 16. figs. 16-19.

The writer is considerably indebted to the members of the
botanical staff at the Purdue Station for the preceding. ARTHUR
in a letter states that “a careful study of this species seems to leave
little doubt that it is a distinctly American species and a short cycle
one. This was the conclusion reached by MAGNus in 1900.” The
one collection known was made by HARKNESS, and a specimen has
been studied by the writer.

7. Uromyces MyrsineEs Diet. Hedwigia 36:26. 1897.

OQ. Pycnia unknown.

III. Telia hypophyllous, crowded upon reddish or brownish
spots 2-10 mm. in diameter, margin of spots usually elevated,
roundish, o.1-o.2 mm. in diameter, often confluent, early naked,
pulvinate, light chocolate-brown, ruptured epidermis inconspicuous;
teliospores oblong or oblong- ellipsoid, 13-16 X 27-39 pw, rounded or

_acute above, narrow below; wall pale golden-brown, rather thin,
1-1.5 u, thickened at the apex, 3-8 4, smooth; pedicel colorless, —
short.

On MyrsINacEakE: Ardisia compressa H.B.K., Costa Rica.

TyPE LOCALITY: Rio de Janeiro, Brazil, on Myrsine sp.

DIsTRIBUTION: Costa Rica; also in South America.

LITERATURE: ARTHUR, Mycologia 10:124, 1918; Sypow, Monog. Ured.
2:46. I900.

1920] BISBY—UROMYCES 209

This rust was known only from South America before its dis-
covery by Hotway in one locality in Costa Rica. South American
specimens have been distributed by E. ULz, Herbarium Brasiliense
no. 2136. ARTHUR suggests that U. marginatus Bomm. and Rouss
may beasynonym. Sypow gives U.Rhapaneae Henn.and U. Usteri-
anus Diet. as synonyms. While Sypow was probably right, it has
been impossible to examine specimens of these two collections.

8. Uromyces Soimpacinis (Sommerf.) Niessl, Verh. Natur.
Ver. Brunn 10:163. 1872.—Caeoma Solidaginis Sommerf. Suppl.
Fl. Lapp. 234. 1826; Caeomurus Solidaginia Kuntze, Rev. Gen.
3°:450. 1898; Telospora Solidaginia Arth., Result. Sci. Congr.
Bot. Vienne 346. 1906.

O. Pycnia not found; probably wanting.

III. Telia bypophylions. sometimes also petiolicolous or cau-
licolous, crowded and often confluent in orbicular groups upon the
leaves, or in elongated groups upon the petioles or stems, 2-10 mm.
across, upon yellowish spots, roundish, small, o.3-o.7 mm. across,
early naked, compact, pulvinate, chocolate-brown, surrounding
epidermis noticeable; teliospores obovate or ellipsoid, 17-25 X
24-33 mM, narrowed or rounded at the ends; wall chestnut-brown,
I.5—3 w thick, much thicker at the apex, 6-12 u, smooth; pedicel
nearly colorless, about as long as the spore.

N CARDUACEAE: Solidago polyphylla Rydb., Colorado; S. serotina Ait.,
Mobinns Washington, Wyoming.

TYPE LOCALITY: Nordland, Sweden, on Solidago virgaurea.

Distr1BuTION: Colorado to Montana and Washington, also in Europe and
Asia.

Ittustrations: Archiv. Naturw. Land. Bohmen 13: fig. 12; Beitr. Krypt.
Schweiz 2?:

Exinccatr: D. Griff., W.Am. Fungi 361; Ellis and Ev.; N.Am. Fungi 2883.

LITERATURE: Cooxe, Grev. 5:152. 1877; WINTER, in Rab. te
Fl. r*:141, 1881; Saccarpo, Syll. Fung. 7:566. 1888; Fiscuer, Beitr. Krypt.
Schweiz 27:59, 543. 1904; FIscHER, Ber. Schw. Bot. Gesells. 15:(1-2). 1905;
Hartor, Les Ured. 216. 1908; Sypow, Monog. Ured. 2:10. 1909.

This is the one species of Uromyces included in this paper which
is not endemic to the Americas. FISCHER (1905) reported cultures
of this rust. He also (1898) pointed out the correlation between
this species and U. Junci (Desmaz.) Tulasne, which bears aecia

210 BOTANICAL GAZETTE [MARCH

upon hosts related to Solidago. The range of both U. Solidaginis
and U. Junci in North America is similar, both occurring in the
western part.

Uromyces Junci-effusi Sydow resembles U. Solidaginis in the
telial stage; the aecial connection is not known for this form.
Curiously not Puccinia Solidaginis Peck, but P. Asteris Duby
(both are short-cycled) shows a correlation with Uromyces Solida-
ginis. Of the short cycle species of Puccinia upon Solidago in
America, one, P. Virgauriae (DC.) Lib., is more eastern, possesses
stromata, and has thin-walled teliospores. P. Solidaginis, although
a western form, has very large teliospores. P. Asteris, however,
is very similar to Uromyces Solidaginis in gross and microscopic
characters, except in the possession of 2-celled teliospores. Puc-
cinia Asteris is a more common rust, and while rare west of the
Rockies, is found over most of North America. Figs. 19-22
illustrate U. Solidaginis from America and Europe and P. Asleris.

Cooke (loc. cit.) reported Uromyces Solidaginis from Maine.
Collections from Eastern North America are not at hand; further
doubt may be attached to Cooxkz’s reported collection from the
fact that he states that the spores are reticulated. GrirritH’s West .
American Fungi 3617, although issued as Puccinia Solidaginis, is
in reality Uromyces Solidaginis.

9. UROMYCES AMOENUS Sydow, Ann. Myc. 4:28. 1906.

QO. Pycnia unknown.

III. Telia hypophyllous, densely grouped and often confluent
on circular purplish spots, 2-8 mm. across, the margin of the spots
yellow, roundish, small, o.2-0.7 mm. across, early naked, compact
pulvinate, dark chestnut-brown, covered by the tomentose pubes-
cence of the host, ruptured epidermis inconspicuous; teliospores
globoid, obovoid, or ellipsoid, 16-23 20-30 w, usually rounded
above and narrowed below; wall dark golden-brown or cinnamon-
brown, moderately thick, 1.5-2.5 wu, apex thicker, 4-7 u, smooth;
pedicel pale yellowish, up to the length of the spore.

CaRDUACEAE: Anaphalis margaritacea occidentalis Greene, Oregon;
A. subalpina (A. Gray) Rydb. (A. margaritacea subalpina A. Gray), Idaho,
ER, es Washington, bab be oat British Columbia
LOCALITY: Washington, on “Gnaphalium (Anaphalis) margaritacea.”
biinieiins Wyoming to British Columbia and Oregon.

1920] BISBY—U ROMYCES 211

Exsiccati: Ellis and Ev., Fungi Columbiani 1795; Barth., N.Am. Ured.
1385,1584.

LITERATURE: Sypow, Monog. Ured. 2:4. 1909; SAcCARDO, Syll. Fung.
213570. 1912.

Several collections of this rust are in the Arthur herbarium.
Although the hosts of some collections are labeled Anaphalis
margaritacea, it would appear that the name A. subalpina should
be used for almost all collections in hand (compare CouLTER and
NeEtson, New Manual of the Botany of the Central Rocky
Mountains, p. 537).

ELits and EverHart’s Fungi Columbiani 1795 was issued as

Uromyces Gnaphalii Ellis and Ev., but is U. amoenus. U.Gnaphalii
has been found to be a synonym of U. iniricatus Cooke.
_ Io. UrRomyces RupBeckiAe Arth. and Holw. Bull. Iowa
Agric. Coll. 1884. 154. 1885.—Caeomurus Rudbeckiae Kuntze,
Rev. Gen. 33:450. 1898; Telospora Rudbeckiae Arth., Result.
Sci. Congr. Bot. Vienne 346. 1906.

O. Pycnia unknown.

III. Telia hypophyllous, occasionally also epiphyllous, densely
gregarious upon brownish spots, paler below, 1-10 mm. across,
rather circinate, small, o.2-0.8 mm. in diameter, early naked,
compact, pulvinate, chinninoh -brown, soon cinereous from germina-
tion, surrounding epidermis not noticeable; teliospores ellipsoid,
obovoid, or pyriform, 11-17 X 19-32 m, rounded, acute, or obtuse
at the apex, narrowed below; wall yellowish or very pale chestnut-
brown, thin, 1 y, apex thicker, 5-8 u, smooth; pedicel hyaline,
twice as long as the spore or less.

—

N CarpuaceaE: Rudbeckia laciniata L. (R. ampia A. Nels.), Colorado,

Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Montana, Nebraska,

ew Mexico, North Dakota, Pennsylvania, Wisconsin, Wyoming, Ontario;
Rudbeckia sp., Texas.

TyPE Locatity: Decorah, Iowa, on Rudbeckia laciniata.

DistriBuTion: Ontario and Pennsylvania to Montana and ec

ItLustration: Arth. and Holw. Ured. Exs. Ic. 1: pl. 1.

Exsiccati: Arth. and Holway, Ured. Exs. Ic. 1: Barth., Facet Columb.
4394; Barth., N.Am. Ured. 299, 1099, 1397; Brenckle, Fungi Dak. 274; Ellis
and Ev. ee Columb. 2097; Ellis, N.Am. Fungi 1439; Rab.-Wint., Fungi
Eur. 3412; Sydow, Ured. 1305, 1962.

212 BOTANICAL GAZETTE [MARCH

LITERATURE: Burritt, Bull. Ill. State Lab. Nat. ‘Hist. 2:163. 1885;
Saccarpbo, Syll. Fung. 7:581. 1888; ARTHUR and Hotway, Bull. Lab. Nat.
Hist. State Univ. Iowa 3:44. 1895; Sypow, Monog. Ured. 2:7-8. 1909.

Uromyces Rudbeckiae has been collected more frequently than
any North American species of the group. Its range embodies the
greater part of the plains area, and extends to the Rocky Moun-
tains.

DieteEL (Ann. Myc. 8:305. 1910) considered Uromyces
Komerovii Bubak on Solidago Virgaurea identical with U. Rud-
beckiae. No specimens of the former have been seen, although a
collection on Solidago Virgaurea in the herbarium has not been
found to differ from U. Solidaginis.

The only other rust found upon Rudbeckia is Aecidium Composi-
tarum Auct., recently found to belong with U. perigynius Halsted
(Mycol. 9:307), a connection suspected from the fact that the
telial stage of U. Rudbeckiae is similar to the telial stage of U. peri-
gynius. A type of correlation which has frequently been of service
in indicating alternate stages of heteroecious rusts is thus evidenced.
The cytological work upon this species is noted earlier in this
paper.

11. Uromyces Bipentis Lagerh. Bull. Soc. Myc. Fr. 11:213,
1895.—Caeomurus Bidentis Kuntze, Rev. Gen. 33:449. 1898;
Uromyces densus Arth. Mycologia 7:196. 1915.

O. Pycnia unknown.

III. Telia hypophyllous, numerous, in small circinating groups
on roundish, discolored spots, 1-4 mm. across, Sometimes confluent,
roundish or oval, o.1-1 mm. across, the central sorus larger, sur-
rounded by smaller ones, early naked, compact, pulvinate, dull
‘cinnamon-brown, becoming waxy-cinereous from germination,
surrounding epidermis inconspicuous; teliospores obovoid or
oblong, 15-28 X30-45 mu, rounded or narrowed above, narrowed
below; wall pale golden or cinnamon-brown, thin, 1 yp, thicker
above, 4-9 #, smooth; pedicel hyaline, once or twice the length
of the sree or less.

Or ACEAE: Bidens ieuconte (L) Willd., Porto Rico; B. pilosa L.,
Porto Rico; Bidens sp., Costa R

TYPE LOCALITY: Ecuador, South America, on Bidens andicola. :

DIsTRIBUTION: Porto Rico and Central America; also in South America.

1920] BISBY—UROMYCES 213

The Sypows (Monog. Ured. 1:3. 1909) misapplied Lacrr-
HEIM’S name to the species with uredinia, now called Uromyces
bidenticola (P. Henn.) Arth. The situation in regard to these two
rusts is discussed by ARTHUR (Mycologia 9:71. 1917), and he also
(Mycologia 10:127. 1918) suggests that it is possible that a
fixity of life cycle may not occur in these Bidens rusts. U. Bidentis
is correlated with U. Bidenticola, differing only in the life cycle
and in the characters of the telia, which are coalescent and thickened
into cushions in U. Bidentis. Specimens are at hand also from
South America; LAGERHEIM’s collection from the type locality
has been examined.

Puccinia Bidentis Diet. and Holw., Bor. Gaz. 24:32. 1897, col-
lected by Hotway in Mexico, apparently is not a correlated species.

EXCLUDED SPECIES

UROMYCES HYALINUS Peck, Bor. Gaz. 3:34. 1878.—U. Sophorae
Peck, Bull. Torr. Bot. Club 12:35. 1885; Caeomurus hyalinus
Kuntze, Rev. Gen. 33:450. 1898; Telospora hyalina Arth., Result.
Sci. Congr. Bot. Vienne 346. 1906.

LITERATURE: SACCARDO, Syll. Fung. 7:581. 582. 1888; Hartot, Revue
Mycol. 14:21. 1892; Sypow, Monog. Ured. 2:128. 1909.

This rust, first described upon Sophora sericea from Colorado,
and made the type of the genus Telospora, has been found to possess
uredinia. OLIvE, in his paper on intermingling of perennial sporo-
phytic and gametophytic generations, etc. (Ann. Myc. 11:309.
1913), mentions that ARTHUR has called attention ‘“‘to the fact
that Uromyces Sophorae seems to possess a similar habit [that is,
an intermingling of mycelia] to the perennial rusts under dis-
cussion.” In any event, the presence of uredinia, in some cases
at least, suffices to exclude this species from the short cycle forms.

Uromyces PavontazE Arth., Bull. Torr. Bot. Club 31:1. 1914.—
Telospora Patoniae Arth., Result. Sci. Congr. Bot. Vienne 346.
1906.

LITERATURE: SACcaRDO, Syll. Fung. 17:250. 1905; Sypow, Monog. Ured.
I:59. Igog.

This rust, described upon Malache scabra B. Vogel (Pavonia
racemosa L.) from Porto Rico and Jamaica, belongs with Puccinia

214 BOTANICAL GAZETTE [MARCH

heterospora Berk. and Curt. An examination of the material shows
that a very few 2-celled teliospores are present. P. heterospora,
upon related Malvaceous plants, is characterized by the preponder-
ance of 1-celled mesospores such as those upon Pavonia.

ARTHUR (Mycologia 9:80. 1917) has given a brief discussion of
the situation here! Uromyces pictus Thuem. upon Abutilon was
also found to possess a few 2-celled teliospores and was placed with
Puccinia heterospora by Sypow (Monog. Ured. 2:58 and 356. 1910).

UROMYCES MONTANA Arth., Bor. GAz. 39:386. 1905.—Telospora
montana Arth., Result. Sci. Congr. Bot. Vienne 346. 1906.

The type collection of this species possessed also aecia, which
were at the time considered to belong with Uromyces Lupini
B. and C. Subsequent collections in Guatemala by KELLERMAN
and Hotway, however, show the same association of aecia and
telia; furthermore, these aeciospores are larger and thicker walled
than the aeciospores of U. Lupini. The grouped arrangement of the

telia and the thin walls of the teliospores and their germination at

maturity indicate a short cycle form, but nevertheless it is con-
sidered probable that the aecia go with the telia. U. elatus Syd.,
also upon Lupinus, shows the same situation as regards association
of aecia with telia resembling those of a short cycle form. I am
indebted to Dr. Matns of Purdue for work upon this species.

Uromyces CupaniAE Arth., Mem. Torr. Bot. Club 17:131.
1918.—Uredo cristata Speg., Anal. Soc. Ci. Argent 17:119. 1884.

This rust, although short-cycled, is excluded from this group,
since, as noted by ARTHUR, it has marked affinities with other groups
of rusts rather than with the group herein treated.

Conclusions

Eleven species of Uromyces possessing only telia and pycnia,
or telia alone, are now considered to be present in North America.
These are found especially in the higher and warmer portions of the
continent, and occur upon 7 widely separated host families.
While these rusts form a group agreeing as to life cycle and
as to the r-celled character of the teliospores, it is not con-
sidered that phylogenetic interrelationship is thereby shown,
morphological evidence indicating rather that the relationship of a

1920] BISBY—UROMYCES z 215
species of these rusts is found in other rusts (of various life cycles
and with 1 or 2-celled teliospores) upon the same or related hosts.
‘Indeed, as indicated under Uromyces heterodermus, a group of hosts
may bear a number of rusts of various life cycles, belonging to
Puccinia and Uromyces, widely distributed geographically, yet all
showing a certain unanimity of morphological characters, especially
in the telial stage.

The writer wishes to express his keen appreciation to Dr. J. C.
ARTHUR for suggesting this paper and for much help, and also to
Professor JACKSON for many suggestions and constructive criticism.
To the other workers in the laboratory at Purdue University he
is likewise greatly indebted.

UNIVERSITY OF MINNESOTA
T. Paut, Minn.

LITERATURE CITED

ARTHUR, J. C., Taxonomic importance of the spermogonium. Bull. Torr.

Bot. Club 31:113-123. 1904.

, Result. Sci. Congr. Bot. Vienne. 346. 1906

———, Cultures of Uredineae in 1905. Jour. Myc. 12:20-21. 1906.

, Uredinales, North American Flora 7:130. 1907.

, North American rose rusts. Torreya 9:21-28. 1909

Bispy, G. R., The Uredinales found upon the Onagraceae. Amer.

Jour. Bot. 3:527-561. 1

7. BLACKMAN, V. H., and Fraser, H. C. I., Further studies on the sexuality
of the Uredineae. Ann. Botany 20:3 mat

8. CARLETON, M. A., Investigations of rusts. Bull. no. 63, Bur. Pl. Ind. 1-29.
1904.

9- Dretet, P., Betrachtungen iiber die Verteilung der Uredineen auf ihren
Nahrpflanzen. Centralb. Bakt. u. Par. 127: 218-234. 1904.
Uber die morphologische Bewertung der gleichnamigen Sporenformen in -
verschiedenen Gattungen der Uredineen. Hedw. 48:118-125. 1908.

, Einige Bemerkungen zur geographischen Verbreitung der Arten
aus den Gattungen Uromyces und Puccinia. Ann. Myc. 9:160-165. 1911.

11. ————, Uber die auf Leguminosen lebenden Rostpilze und die Verwandt-

schaftsverhiltnisse der Gattungen der Boe eons Ann. Myc. 1:3-14.
1903; see also Ann. Myc. 10: 205-213.
- Fiscuer, Ep., Eeiwahineeceaaaeas Untersuchungen iiber Rost-
pilze. Beitr. Krypt. Schweiz 1:7-8. 1898.

La]
.

SE ey

al
Nu

216 BOTANICAL GAZETTE [MARCH

13. FIscHER, Ep., Recherches sur les Urédinées suisses. Berne, 1898; original

not seen; abs. by Hartor, Paut, Les Urédinées, pp. 83-85. Paris. 1908. —
14. ———, Fortsetzung der Entwickelungsgeschichtlichen Untersuchungen
iiber Hoatpilee. Ber. Schweiz. Bot. Gesells. 15:1-13. 1905.

, Uber den Einfluss des Alpinen Standortes auf den Entwickelungs-
gang der Urédinéen. Verh. Schweiz Nat. Ges. 88:47. 1906.

16. HorrMan, A. W. Hans, Zur Entwickelungsgeschichte von Endophyllum
Semperviri. Centralb. Bakt. Par. 327:137-158. 1911:

. Macnus, P., Uber die auf Compositen auftretenden Puccinia mit Teleuto-
sporen von Typus der Puccinia Hieracii nebst Andeutungen iiber den
Zusammenhang ihrer specifischen mit ihrer vertical Verbreitung. Ber.
Deutsch. Bot. Gesells. 11:453-464. 1893; see also Hedw. Beibl. 39:147-

-
~I

2
°
=
Po

Mme F., Les phenomenes de la sexualite chez les Urédinées.
These de la Faculti des sciences ]’Universite de Paris. Ser. 779, no. 1563,
Portiers. 1914: pp. 142. pls. 14. 1914; original not seen; review by
FISCHER, Ep., Zeitsch. Bot. 8:360-362. 1916.

19. OLIVE, E. W., The nuclear condition in certain short-cycled rusts icbatsee
Science 33:194. IQII. -

, Sexual cell fusions and vegetative nuclear divisions in the rusts.
Ann. iotens 22:331-360. pl. 22. 1908.

21. ORTON, - R. sivas og ido species of Allodus. Mem. N.Y. Bot. Gard.
6:175-20 rash

22. en, J., Recent published results on the cytology of fungus
reproduction. Trans. Brit. Myc. Soc. 5:271-303. 1916.

23- SAPPIN-TROUFFY, P. aera: histologiques sur la famille des Urédinées.
Le Botaniste 5: 59-244.

24. SCHNEIDER, WERNER, ise Biologie der Liliaceen bewohnenden Uredineen.
Centralb. Bakt. u. Par. 327:452. 1912.

25. Sypow, P and H., Monograph. Ured. 2:1-296. 1909-1910.

26. WERTH, E., and Lupwics, K., Zur Sporenbildung bei Rost- und Brand-
pilzen. (Ustilago antherarum Fries und Puccinia malvacearum Mont.)
Ber. Deutsch. Bot. Gesells. 30:522-528. 1912

27. WILLE, F., Zur Biologie von Puccinia Arenariae (Schum.) Wint. Ber.
Deutsch. Bot. Gesells. 33:91-95. 1915

EXPLANATION OF PLATE X

All figures were drawn at the level of the stage with the aid of a camera
lucida, with Leitz 1/12 oil immersion and ocular 4. Théy are here reduced
one-third, so that the magnification is 667 diameters. Surface markings, where
present, are indicated, and the stippling on the aan cross-section diagrams |

PLATE X

BOTANICAL GAZETTE, LXIX

BISBY on UROMYCES

1920] BISBY—UROMYCES a

represents to some degree the comparative darkness of color of the spore walls.
In most cases the drawings of short cycle Uromyces were made from type
material.

Fics. 1, 2.—Surface and optical cross-section, respectively, of teliospores
of Uromyces heterodermus Syd., from type material, on Erythronium parviflorum,
Wasatch Mountains, ae Lake County, Utah; A. O. Garrett, Fungi Utahensis
118. ;

. 3, 4.—Uromyces Erythronii (DC.) Pass. on se asishe ae dens-canis,

‘ Fees Sydow, Ured. 1505; species correlated with prece

Ics. 5, 6.—Uromyces Holwayi Lagerh. on Lilium ian Wash-

dete Barth., N.A. Ured. 1387; compare two preceding species
; 8.—U romyces bauhiniicola Arth., from type material on :Bibiaes
oe Guadalajata: Mexico.

IGS. 9, 10.—Uromyces jamaicensis Vesterg., from type material, on
Bauhinia sp., Constant Spring, Jamaica.

IGS. 11, 12.—Uromyces abbreviatus Arth., from type material, on Psorlea
Purshii, Winns ates: Nevada. Griffith, W.Am. Fungi 390.

IGS. 13, 14.—Uromyces Tranzschelit Sydow, from type material, on Tithy-
malus (Euphorbia) montana, Fossil Creek, Colorado. Ellis and Everhart,
Fungi Columbiana 1069.

Fics. 15, 16.—Uromyces nevadensis Hark., from type material, on Primula
ce ag near Lake Tahoe, Nevada.
3:19, 18, oo Myrsines Diet. on Ardisia compressa, south of
oo. Costa
FIGs. 19, 20. “Uy romyces Solidiveinds (Sommerf.) Niessl. on Solidago en,
gre Montana. Ellis and Everhart, N.A. Fungi 2883.
G. 21.—Uromyces Solidaginis on Solidago virgaurea, Sweden. Sydow,
Ured.: Sees
Fic. 22.—Puccinia Asteris Duby on Aster aagiae Salt Lake County,
tee stating correlation with Uromyces Solidagi
3, 24.—Uromyces amoenus Sydow, from pen cues on Ana Ages
reli, Paietis Valley, Mount Tacoma, Washin
25, 26.—Uromyces Rudbeckiae Arth. and ogee from type’material,
on a laciniata, Decorah, Iowa.
Fics. 27, 29.—Uromyces Bidentis Lagerh. on Bidens pilosa, Ponce, Porto
Rico, from type material of Uromyces densus Arth.
Fic. 28. Soca Bidentis from material from type locality on Bidens

_andicola, Ecuador

EFFECT OF SALTS UPON OXIDASE ACTIVITY OF
APPLE BARK

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 263
D. H. Rose, HENRY R. KRAYBILL, AND R. C. ROSE
(WITH FIVE FIGURES)

Introduction

In an earlier paper (21) one of the authors showed that there is a
marked difference in the action of the salts of the alkali metals upon
the fire-holding capacity of tobacco, even when the salts have
similar anions. For instance, the carbonates of potassium,
rubidium, and caesium promote the combustion of tobacco to a
very much greater extent than the carbonates of sodium and
lithium. The chlorides of sodium, lithium, and potassium retard
the combustion, but the chloride of potassium is not nearly so
effective as the chloride of sodium or lithium. In general, the
salts of potassium, rubidium, and caesium are much more favor-
able to combustion than those of sodium and lithium.

It has been known for a long time that potassium is an essential
element for the higher plants. Numerous attempts have been
made to replace potassium by sodium, and, while apparently sodium
can fulfil some of the functions of potassium, attempts to replace
potassium entirely by sodium have been unsuccessful. The fact
that potassium seems to have such a marked property of promoting
the combustion of tobacco, and sodium does not, suggests that this
particular property of potassium may have a relation to certain
functions in the plant, which cannot be fulfilled by sodium. These
facts suggested that a study of the effect of the alkali salts upon
oxidase activity might be of interest. The work reported in
this paper was done in 1917. More extended studies were
planned, but, since it has been impossible to carry them out com-
pletely at the present time, it seemed wise to report the results
obtained.

Botanical Gazette, vol. 69] [218

A

1920] ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY 219

Historical

_ BERTRAND (5) was the first investigator to point out that the
salts of metals influence oxidase activity. He showed that man-
ganese salts greatly increase the oxidase activity of preparations
from alfalfa. GrSSARD (15) found that the formation of melanin
from tyrosin is increased in the presence of salts of the metals.
Bacu (4) substantiated Grssarp’s results, and showed that
aluminum sulphate, salts of calcium, magnesium, manganese,
and zinc increase melanin formation from tyrosin. The effect of
the salts is to increase the further change of the oxidation product
rather than to activate the taking up of oxygen. Aluminum
salts hasten the formation of purpurogallin from the yellow
oxidation product of the action of oxidase upon pyrogallol. Bac
believed that the oxidation process is retarded by the accumula-
tion of the primary oxidation products, and that the salts act
to release them. Wotrr (32) found that the oxidation of tyrosin
by tyrosinase from Russula delica is increased by the addition
of small quantities of disodiumphosphate. PoropKko (26), Aso (3),
ALSBERG (2), and Ewart (11) have shown that salts of the metals
give a blue color with guaiacum. Poropko and Ewart believed
these salts to be inorganic oxidases. PoropKo pointed out that
those metals which form salts of two degrees of oxidation are par-
ticularly active. ALsBERG, and also Ewart, confirmed PoropKo’s
observation and found that the chlorides of many of the met-
als give a blue color with guaiacum. ALsBERG attributed an
important part in the reaction to the chlorine. Ewart further
found that the chlorides, nitrates, and sulphates of the same metal
are not necessarily equally powerful in their action. Apparently
the chlorides are more active than the sulphates. Various salts
were found to act as sensitizers or retardants to oxidase activity.
Potassium chloride, potassium iodide, potassium bromide, and
potassium fluoride retard or even prevent the browning of pounded
apple pulp.

Numerous investigators have shown that oxidase activity is
affected by changes in reaction of the medium, BERTRAND (6)
showed that the action upon guaiacol of laccase from Rhus succe-
danea is inhibited by 0.002 M concentration of sulphuric acid.

220 BOTANICAL GAZETTE [MARCH

Wo rr found tyrosinase from Russula delica most active in a
solution neutral to phenolphthalein, and ABDERHALDEN and GUG-
GENHEIM (1) found that tyrosinase is destroyed by 0.016 N hydro-
chloric acid, and greatly retarded by 0.016 N sodium hydroxide.
Rose (28) showed that the decrease in oxidase activity, as observed
in the Bunzell apparatus, is due to an increase in the hydrogen ion
concentration of the medium. ReEeEpD (27) found oxidase activity
in potatoes and apples inhibited even by low hydrogen ion con-
centrations; and likewise BuNzELL (9) found the action of oxidase
retarded with increasing hydrogen ion concentrations.

Methods

All but one of the experiments described in this paper were made
with portions of apple bark which had been dried at 35-40° C.
for 2-3 hours, ground fine enough to pass through a 40-mesh wire
sieve, and stored air dry in zinc-capped Mason jars. One experi-
ment was made with solutions of precipitated oxidase separated
from aqueous extracts of healthy bark and of diseased bark by the
addition of about 10 volumes of alcohol. In order to obtain the
precipitated oxidase, 2 gm. of bark were allowed to stand in a
beaker with 10 cc. of water and 5 drops of toluol for 1 hour. The
extract was then squeezed out through moist cheesecloth on coarse
filter paper. The beaker was washed with five 1 cc. portions of
water and the filter paper finally with two more. There was then
added 50 cc. of 95 per cent alcohol to the filtrate (concentration of
alcohol about 7o per cent) and the whole allowed to stand for
10 minutes. The flocculent precipitate which had formed was
collected on a hard filter by gentle suction with a filter pump.
There was then added 150 cc. more alcohol to the filtrate (con-
centration of alcohol now about 90 per cent) and the whole
allowed to stand for 1 hour, since precipitation was slow, _ before
this second fraction was collected on the filter with the first.
The precipitate was dissolved in water and used immediately, as
described later. :

The stock solutions of all of the salts tested were made to a
concentration of o.5 N. Potassium chloride, manganese chloride,
ferrous chloride, and ferric chloride were used also in the additional

1920] ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY 221

concentrations of o.1 N and o.o1 N. Since there was always
5 cc. of water in the apparatus, the final concentration of the salt,
there was 0.1 N for o.5 N solutions and 0.02 and 0.002 N for
o.1 N and o.o1 N solutions used.

Oxidation was measured in centimeters of mercury rise by
means of the simplified BUNZELL apparatus (8). The shaking ma-
chine was run at the rate of 106 complete excursions per minute. All
experiments were run for 3 hours, readings being taken every 15 min-
utes, and a final reading the following morning. When bark was used,
the mixtures in the apparatus contained o.1 gm. of bark, 1 cc. of
salt solution, and 4 cc. of 1 per cent pyrogallol solution or salt
and pyrogallol with bark omitted, the second combination serving
as a control on the first. Preliminary experiments had shown that
during the time in which these experiments were run the auto-
oxidation of the pyrogallol was usually not more than the equivalent
of o.15 cm. mercury rise. In the experiment with precipitated
oxidase, the precipitate from 2 gm. of bark was dissolved in 20 cc.
of water, and 2 cc. of the solution, containing the dissolved precipi-
tate obtained from o.2 gm. of bark, were put in each apparatus,
together with the usual amount of pyrogallol and water. All tests
were run in duplicate. Two controls were run with each experi-
ment, one containing only water, the other bark (or oxidase solu-
tion), pyrogallol, and water, but without the addition of salts.

_ The figures for P,, given in table VII were obtained by means of
the apparatus described by RosE (28).

Discussion

The chlorides in general retard oxidase activity. The chlorides
of potassium, sodium, and lithium depress markedly the oxidation
of pyrogallol by bark (table I). Similar results were obtained with
all the other chlorides tested, except ferrous chloride (table VI).
Ferrous chloride in o.1 N concentration with bark and pyrogallol
Showed 1.79 cm. mercury rise, and with pyrogallol alone 1.45 cm.,
compared with the control of pyrogallol and bark as 1.00 cm.
Since ferrous chloride is readily oxidized when exposed to the
air, it is quite probable that the oxygen absorption for the most
part represents that absorbed in the oxidation of ferrous chloride.

222 BOTANICAL GAZETTE [MARCH

Results
The results of the experiments are shown in tables I-VII and
fips. 15.
TABLE I

EFFECT OF 0.1 N KCl, NaCl, anv LiCl ON OxIDATION OF piaagirnone BY POWDERED
ALTHY APPLE BARK; TEMPERATURE 23.2-23.6

No BARK BarRK
TIME OF READING od caer a
KCl NaCl LiCl Check KCl NaCl LiCl
May 21
$2 BOs oO. 0.00 0.00 oO. 0.00 0.00 fe)
Oy 4 eee 0.03 0.13 0.00 0.03 0.06 0.07 0.03
POO G2: 0.03 0.13 0.00 0.08 0.05 Oil 0.05
gah ae asi 0.08 0.20 0.00 0,23 o.15 0.18 0.15
Di, Pre 0.05 Gix7 0.02 0.25 O45 0.18 O.95
Tae. 0.0 O13 0.00 0,33 0.15 0.21 0.15
F500 6 ss 0.07 0.18 0.00 0.38 0.15 0.24 0.16
es eae 0.08 0.19 0.05 0.43 0.19 0.27 a. 3%
Pi Fe eee 0.08 0.19 0.04 0.45 0.19 0.31 0.25
PAE ST: 0.07 0.17 0.05 0.45 0.25 0.30 0.25
Pe Res 0.05 0.16 0.05 0.50 0.23 0.32 9.26
oe Pe 0.09 | 0.19 0.06 0.65 0.26 0.36 o.79
3-30, 2 ss 0.10 0.20 0.05 0.68 °. 28 0.35 0.32
May 22
pe See 0.00 0.00 0.00 1.25 0.80 0.74 0.77

na ee SPU
* In tables I-V manometer readings in cm. of mercury corrected against an apparatus containing
only water.

Fic. 1.—Effect of KCl, NaCl, and LiCl on oxidation of pyrogallol by powdered
healthy apple bark: A, control (bark and pyrogallol); B, arth bark and pyrogallol;
C, NaCl+bark and pyrogallol; D, LiCl+bark and pyrogallol

1920] ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY 223

TABLE II
EFFECT OF 0.10 x ALKALI CARBONATES ON OXIDATION OF PYROGALLOL BY POWDERED
ALTHY APPLE BARK; TEMPERATURE 29.3-30.0° C.

No BARK Bark

TIME OF READING
K.CO, N: aaCO; Li,CO, Check KC O; Na,zCO; Li. CO;

cn a 98888)

#

2.—Effect of K,CO, on oxidation of pyrogallol, with and without bark
(hath) ): A, BsCOybark and pyrogallol; B, B.CO, + pyroglll foun (bark

224 ~BOTANICAL GAZETTE [MARCH

TABLE III

EFFECT OF 0.10 N KCl anp K,CO; ON OXIDATION OF PYROGALLOL BY POWDERED
DISEASED APPLE BARK; TEMPERATURE 27.8-29.0

No BARK : BARK
TIME OF READING
K:00; KCl Check K:CO; KCl
March 10
TO O08 sy ct oO. 0.00 0.00 0.00 0.00
Nee ie ee 0.68 —0.05 0.13 ©. 46 0.16
10.3050 eee 1.24 0.00 0.30 0.90 0.33
4048 1.65 0.00 0.50 38 0.38
ee a ere 1.98 —o.08 0.65 1.50 0.48
PRE ee 2.25 —0.03 0.72 1.72 0.60
5 BEER. peahenigar ye Mane nom 2.38 —0.03 -} 0.85 1.93 0.69
ce ne Agea ts Bare ee 4.53 0.00 ©.99 2 0.82
POOL isi. ss 2.65 —0.05 1.04 2.22 0.88
5 Be Near ee | a8 0.00 i. 15 2.35 0.95
ESO Sen Sys 2.78 —0.05 1.18 2.30 0.95
Dag ee ea 2.85 0.08 i. 25 258 1.00
OO Ge an 2: —0:9. I.38 2.6 1.10
March 11 is : : :
cer Saye a:53 —o.10 2.20 +73 1.73

a naanen seen

Hy
y
rt
48
ae
ii
f
_-.
7 2
4a
aa
seo
ae
iti
Lil
ee
2 2
Ci
‘as a!

Fic. 3.—Effect of KCl and K,CO, on oxidation of pyrogallol with and ane
bark (diseased): A, control (bark and pyrogallol); B, K,CO,+-bark and yrogallol; — -
I ek BE a= D, KCl+bark and pyrogallol (KCl+pyrogallol gave PO

xidation). : as

kare

1920]

ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY

TABLE IV

225

EFFECT OF 0.10 N POTASSIUM TARTRATE, SODIUM OXALATE, AND Si ON
OXIDATION OF PYROGALLOL BY POWDERED HEALTHY APPLE BARK
TEMP xb &

ERATURE 29. 2-3

No BARK Bark
TIME OF READING ; .
feorrg oxalate | CA(NOs)2| Check grrr cas Ca(NOj)s
June 22 Pe
tae, (© See ase 0.00 ©.00 0.00 0.00 0.00 0.00 0.00
P46 a O.II 0.08 °o.18 °.1I0 0.14 0,20 0.08
ZOO rh. See Cee eee eee ela ees 0.25 0.28 0.25 0.20
eh te ee 0.25 0.10 0.20 0.30 0.36 0.35 0.23
BAO hae ae es oe ee 0.38 0.48 0.46 0.30
ey oes 0:35 °.19 0.20 0.43 0.58 0.55 0.35
BOO. SE coe ete 0.55 0.64 0.64 0.40
5, ee ay 0.48 0.31 °. 28 0.58 0.76 0.78 0.50
BOO: AW eh es alee ys ee ed 0.70 oO. 0.80 0.55
re Se eos gary eels orale Sieg Gy epenoes sy 0.95 0.96 0.59
A OOo: 0.68 0.38 0.35 0.80 1.03 1.00 0.60
BTS Es OE. ee oa es eee °.90 1.4% I.10 0.73
Se Pa ee ee 0.78 0.35 0.38 °.90 1.15 eS 0.70
June 23
ot Ge 0.95 0.68 0.23 1.20 1.63 1.60 0.98

Fic. 4.—Effec

t of potassium tartrate on oxidation of pyrogallol with and without
bark (healthy): A, control (bark and ee B, potassium tartrate+bark and
Pyrogallol; C, potassium tartrate+pyrogallol.

226 BOTANICAL GAZETTE . [MARCH

TABLE V

EFFECT OF 0.10 N MnCl, anp K,SO, ON OXIDATION OF PYROGALLOL BY PRECIPITATED
OXIDASE FROM BOTH HEALTHY AND DISEASED APPLE BARK; TEMPERATURE
5 te)
24

HEALTHY DISEASED
TIME OF READING ,

Check MnCl K.SO, Check MnCl K.SO,

June 21 -
ey 1 re Nee arn 0.00 O. 0.00 ©.00 0.00 0.00
BOOS ce a 0.07 0.08 o.II 0.17 0.15 0.15
1 9 alee oe dae ect 0.08 0.10 0.21 0.37 0.29 0.30
2 OC ty faa va 0.08 0.13 0.23 0.42 oO; 2% 0.33
BAR ie 4 oe oe eek 0.08 0.13 6.39 0.48 0.25 0.43
RO a ey Eee eS tos 0.08 0.10 0.25 0.50 0.23 0.48
BOWS eis cee ee 0.15 OLE 0. 28 0.56 0.24 0.54
BAO ee ey vai 0.15 0.08 0.30 0.65 0. 26 0.58
PEST ie RAR i ea 0.18 0.09 0.35 0.70 0.29 0.63
BR aes Po ice 3 0.20 0.08 0.34 0.79 0.31 0.69
BAR er ©. 20 0.08 0.37 0.87 0.34 0.78
B30 cos yeu ck oe oes 0.23 0.09 0.38 0.88 0.35 °.78
Pe ee aie Ge 0. 28 0.18 0.43 0.98 0.40 0.93

June 22

ery wee. 0.53 0. 28 0.58 1.24 0.63 1.28

po Ld

Fic. 5.—Effect of MnCl, and K,SO, on the oxidation of abe ne on ee
oxidase from both healthy and diseased bark: A (diseased), K,SO,+ba
gallol; B (diseased), cite ol (bark an pyrogallol); C (diseased), M MnCl,+bark P and
pyrogallol; D (healthy), K.SO,-+bark and pyrogallol; E (healthy), control (bark
and pyrogallol); F (healthy), MCal, tberk'en pyroga! gallo a

227

ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY

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1920]

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[MARCH-

BOTANICAL GAZETTE

228

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1920] ROSE, KRA YBILL, & ROSE—OXIDASE ACTIVITY 229

This view is substantiated by the fact that when the concentration
of ferrous chloride is reduced, oxygen absorption is reduced pro-
portionally (table VI). If we subtract 1.45 cm. (mercury rise
for pyrogallol and ferrous chloride) from 1.79 cm. (mercury rise
for bark, pyrogallol, and ferrous chloride), we have 0.34 cm. for
the oxidase activity of the bark in the presence of the ferrous
chloride as compared with 1.00 cm. for the oxidase activity of
bark and pyrogallol in the absence of ferrous chloride. Apparently
ferrous chloride retards oxidase activity just as the other chlorides
do, and the increased absorption of oxygen in the presence of
‘ ferrous chloride is due to the action of ferrous chloride itself in
absorbing oxygen. Oxidation is increased by 0.002 N manganese
chloride. This is in accord with the results of BERTRAND (5) and
others. In a concentration of 0.1 N it inhibits oxidation just as
do the other chlorides.

The use of precipitated oxidase shows that chlorides have a
depressing effect on oxidation, even under conditions which elimi-
nate many of the substances present in the bark powder. No
investigation has been made of the effect of these substances on |
the reaction, but they probably complicate it.

The results with the chlorides are in accord with the work
of Ewart, who found that dilute solutions of potassium
chloride and sodium chloride prevent the browning of slices
of apples. Ewart’s further conclusion, however, that the chlo-
tides act as sensitizers to oxidation, or ALSBERG’s idea that
chlorine plays an important part in the bluing of guaiacum by
the chlorides of metals, are scarcely borne out by our observations
that chlorides in general depress oxidase activity. It should be
noted, however, that the results of those investigators were
based upon color reactions, while ours were-based upon oxygen
absorption.

It is interesting to note that the chlorides which retard the
combustion of tobacco at high temperatures have a similar effect
in depressing oxidase activity. KRAYBILL (21) has suggested that
the chlorides may have a negative catalytic action in the case of
the combustion of tobacco. It would be interesting to know
how the chlorides affect other oxidation processes. .

230 BOTANICAL GAZETTE [MARCH

The depressing effect of chlorides on oxidase activity is in
contrast with their action on other enzymatic processes. Thus
NAsse (25), Kiser (22), Cote (10), WOHLGEMUTH (31), LISBONNE
(23), Hawkins (18), and others have found that chlorides increase
the diastatic power of various preparations of diastase. NASSE,
however, found that under certain conditions sodium chloride
retarded diastatic activity, and later Hawkrns showed that sodium
chloride and potassium chloride in certain dilute concentrations
(M/128-M/s12) retard diastatic activity. It would have been
better if the effect of the chlorides upon oxidase activity had been
determined in a greater number of concentrations, and it will be well |
in the future to do so in studying this problem. The effect of salts
upon lipase activity is also of interest in this connection. LOEVEN-
HART and PEIRCE (24), GERBER (14), TERROINE (30), HAmstx (16),
FAK (12), and others found that the chlorides of various alkalies
and alkaline earths retard lipase activity. TERROINE found that
the concentration of the salts which he studied determined the
nature of their influence. BUCHNER, BuCHNER, and Haun (7)
found that the chlorides of sodium, calcium, barium, and am-
monium inhibit the fermentation of cane sugar or glucose in the
presence of pressed yeast. :

The results presented in table VI do not show any marked differ-
ence in the behavior of the different chlorides tested. The cations,
judging from the limited data available, apparently have little
or no effect; or at least their chlorides all behave very muc
in the same manner. In this respect the alkali salts are different
in their effect upon the fire-holding capacity of tobacco, for here
the salts of caesium, rubidium, and potassium in general are much
more favorable to combustion than the corresponding salts of
sodium or lithium.. A similar contrasting behavior of different
cations of chlorides was noted by HARDEN (17), who found that
potassium chloride and ammonium chloride cause a definite degree
of fermentation in inactivated yeast, while sodium chloride has no
effect. He says: ‘‘A specific difference in relation to alcoholic
fermentation exists between the ions of sodium on the one hand and
of potassium and ammonium on the other hand.” SCHREINER and
SULLIVAN (29) found that potassium salts retard oxidation by the
roots of plants.

1920] ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY 231

The effect of the chlorides of the alkalies in retarding oxidase
activity suggests a possible practical application in preventing the
browning of fruits and vegetables during their preparation for
canning, preserving, or drying.

The sulphates apparently increase oxidation slightly in all
cases, but the readings are not sufficiently large to be of any positive
significance.

The nitrates of potassium, sodium, and magnesium have no
marked effect on oxidation, while the nitrates of barium, calcium,
manganese, and iron (ferric) decrease it. These results are similar
to the effect upon respiration as found by ZALESKI and REINHARD
(33). FrernBacw and LANZENBERG (13) and Kayser (20) find
that nitrates increase alcoholic fermentation, but, as they point out,
the effect may be to increase multiplication of the, yeast cells
rather than to affect enzymatic action.

In tables II and III and figs. 2 and 3 are shown the oxidation
of pyrogallol by bark alone, by bark and carbonate, and by carbon-
ate alone. From these it is seen that in the last two cases oxidation
is considerably greater than that by the bark alone. It is also
seen that during the first 3 hours oxidation by carbonate is greater
than that by carbonate and bark, but that after the experiment
has stood overnight oxidation by healthy bark and carbonate
approaches that by carbonate alone, and oxidation by diseased
bark and carbonate exceeds it.

The most obvious explanation of this fact, although possibly
not the true one, is that oxidation by a carbonate is a strictly
chemical reaction, catalyzed only by hydroxyl ions, which soon
comes to a definite end, while oxidation by carbonate and bark
is a reaction catalyzed by both “oxidase” and hydroxyl ions, in
which the presence of the hydroxyl ions increases the effectiveness
of the “oxidase,” which is slow in reaching an end-point.

Table VI shows that tripotassium phosphate increases oxida-
tion of pyrogallol very markedly, both with and without bark.
Although no P, values for this mixture are available, we know the
salt is alkaline in reaction, and this effect complicates the matter.
With potassium dihydrogen phosphate at o.10 N concentration a
decrease is evident, and at 0.02 N and 0.002 N concentrations a

232 BOTANICAL GAZETTE [MARCH

slight increase in oxidation occurs. The higher hydrogen ion
concentration is probably the cause of the slight depression in
oxidation of the o.10 N strength of the salt. The slight increase
in oxidation of the lower concentrations suggests that phosphates
may increase oxidase activity, but the limited data are inconclusive.
It is interesting to note that IwanorF (19) found that phosphates
raise the amount of respiration in living wheat seedlings. ZALESKI
and REINHARD (33) found that disodium phosphate increases the
output of carbon dioxide from dried ground seeds, and that the
monobasic phosphate decreases it because of the acid reaction.
These authors also quote from the work of a student, Miss
ScHKLOUsSKy, who showed that phosphates increase the action of
peroxidases, and from work of another student, Miss ROSENBERG,
who showed that phosphates acca anes the catalase activity of
different seeds.

In the case of salts of organic acids and the carbonates, all
more alkaline than any of the inorganic salts (table VI), oxidation
is greater at all stages of the experiment when bark is used than
when it is not. Examples of this are shown in table IV. The
effect of the salt is not merely additive, however, either here or in
the case of the carbonates, as is shown by the following:

OXIDATION OF PYROGALLOL BY BARK AND SA
1

ested separately Tested onsen
(cm, of mercury rise) (cm rise)
pee a ee 4.4 De ais
K tartrate paper ao 2.28 253
A OfAate 1.88 1.60

Evidently when bark and salt are combined, there is some factor
at work which brings about a slower rate of oxidation than might
be expected. What this factor may be we have no means of
knowing as yet. Possibly it is the partial neutralization of the
hydroxyl ions of the salt by the acid of the bark.

The question why salts vary so widely in the effect they have
on oxidation is not easily answered. If we consider only the
results with 0.1 N solutions, it seems clear, in the case of the car-
bonates, potassium dihydrogen phosphate, and the salts of organic
acids here reported, that increased oxidation in their presence is
due to the excess + of hydroxyl i ions they furnish; that is, by the

1920] ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY 233

reaction (P,) their solutions establish when mixed with bark and
pyrogallol (table VII). The reaction established by the chlorides,
however, can hardly be responsible for the decrease in oxidation
they bring about, since sulphates, giving about the same reaction,
cause a small increase in oxidation. For example, a mixture of
potassium chloride, bark, and pyrogallol has a Pi, of 5.19 and gives
only 63 per cent as much oxidation as the control. A similar
mixture containing potassium sulphate has a P, of 5.13 and gives
7 per cent more oxidation than the control. The corresponding
figures for manganese are: manganese chloride mixture, P»=4.50,
oxidation = 104 per cent of the control.

The situation for nitrates shows several irregularities. Potas-
sium nitrate giving a P, of 5.14 has practically no effect on oxida-
tion. Magnesium nitrate is also without effect, but gives a P, of
4.62. The nitrates of calcium, barium, and manganese inhibit
oxidation, but manganese gives a lower P, and the other two a higher
one than that given by magnesium nitrate.

The results presented justify the conclusion that when o.1 N
solutions of the salts are used, other ions than hydrogen and
hydroxyl] play an important part in controlling oxidation. When

ydrogen or hydroxyl ions are neutralized in making oxidase
activity determinations, therefore, it is important to take into
consideration the possible effect of the salts formed thereby. This
must be considered as merely preliminary to the real investigations ~
of the relation of specific ions to the oxidation processes in plants
and animals. The effect of iron and manganese salts has long been
known, but more work is necessary, both with these and wit
the more commonly occurring chlorides, sulphates, and nitrates of
other cations.

Summary
1. One-tenth normal solutions of all of the chlorides tested
(potassium, sodium, lithium, caesium, ammonium, calcium, man-
ganese, ferric) decreased oxidation of prea! by apple bark
powder.
' 2, Oxidation was jeeeed very slightly by 0.10 N solutions
of all the sulphates tested.

234 BOTANICAL GAZETTE : ‘ [MARCH

3. Potassium, sodium, and magnesium nitrates (0.10 N)
had practically no effect on oxidation, while nitrates of calcium,
barium, manganese, and iron (ferric) decreased it.

4. Potassium chloride (0.02 N and 0.002 N) had no effect on
oxidation, while manganese chloride in these concentrations
increased it.

5. Tartrates, oxalates, citrates, acetates, and carbonates
increased oxidation. Marked increase in oxidation in these cases
seems to be due, in part at least, to the low acidity of the mixtures
_of bark, pyrogallol, and salt.

6. Marked decrease in oxidation is not necessarily accompanied
by high acidity of the mixtures.

7. Ions other than the hydrogen and hydroxyl may be important
in regulating oxidase activity.

8. In neutralizing hydrogen or hydroxyl ions, it is important
to take into consideration, in the study of oxidase activity, the
possible effect of the salts formed thereby.

9. The chlorides which retard the combustion of tobacco at
high temperatures also retard the oxidase action at low tempera-
tures.

10. The effect of the alkali chlorides upon oxidase activity
suggests a practical application in preventing the browning of
fruits and vegetables during their preparation for canning, pre-
serving, or drying.

The authors wish to express their appreciation to Dr. WM.
CROCKER for many helpful suggestions.

BurEAv or PLant INDUSTRY
Wasuincton, D.C.

LITERATURE CITED
1. ABDERHALDEN, EMIL, and G , Markus, Versuche iiber die Wirk-
ung der Tyrosinase aus Russula ddica: auf Tyrosin, tyrosinhaltige Poly-
peptide und einige andere Verbindungen unter verschiedenen Bedingungen.
Zeit. Physiol. Chem. 54:331-353. 1907-1908.
2. ALSBERG, Cart L., Beitrige zur Kenntnis der Guajak-Reaktion. Arch.
Exp. Path. und Pharm. Festschrift. Schmiedeberg, pp. 39-53- 1908.

1920] ROSE, KRAYBILL, & ROSE—OXIDASE ACTIVITY 235

3.

>

on

oO

?

Sad
°

Lal
Lal

Lond
id

-—
w

Lan]
>

Aso, K., On oxidizing enzymes in the vegetable body. Bull. Coll. Agric.
Imp. Univ. Tokyo 5: 207-235. 1902

- Bacu, A., Zur Theorie der Oxydasewirkung. II. Einflusz der Metallsalze

auf die weitere Umwandlung der Produkte der Oxydasewirkung. Ber.
Deutsch. Chem. Gesells. 43:366-370. 1910.

- BERTRAND, G., Sur l’action oxydante des sels manganeux et sur la consti-

tution chimique des oxydases. Compt. Rend. 124:1355-1358. 1897.
, Sur l’intervention du manganese dans les oxydations provoquées
par la laccase. Bull. Soc. Chim. 17:619-624. 1897.

- BUCHNER, EDWARD, BUCHNER Hans, and Hann, Martin, Die Zymase-

garung. Munchen und Berlin. 1903.

. BUNZELL, H. H., A simplified and inexpensive oxidase apparatus. Jour.

Biol. Chem. 17:409-411. 1914.

———.,, The relationship existing between the oxidase activity of plant
juices and their hydrogen ion concentrations, with a note on the cause of
oxidase activity in plant tissues. Jour. Biol. Chem. 28:315-333. 1916.

- CoLe, S. W., Contributions to our knowledge of the action of enzymes.

I. The influence of electrolytes on the action of amylolytic ferments.
Jour. Physiol. 30: 202-220. 1903.

- Ewart, A. J., A comparative study of oxidation by catalysts of organic

and inorganic origin. Proc. Roy. Soc. London B 88: 284-320. 1914.

- Fark, I. S., The influence of certain salts on enzyme action. Jour. Biol.

Chem. 36:229-247. 1918.

- Fernspacu, A., and LANZENBERG, A., De l’action des nitrates dans la

fermentation alcoolique. Compt. Rend. 151:726-729. 1910

. GERBER, C., La lipase des latex, comparaison avec celle des graines. VI.

Action des sels neutres, des elements halogenes et de l’eau oxygenée sur
la saponification du jaune d’oeuf par la lipsae a aw d’Euphorbia Char-
acias. Compt. Rend. Soc. Biol. 76:136—141.

GeEssarp, M. C., Sur la tyrosinase. Compt. athe 130: 1327-1330. 1900.
Hamsik, A., bag Kenntnis der Pankreaslipase. Zeit. Physiol. Chem.
71:238-251. Igrl.

- Harpen, Artuur, The condition of activation of washed zymin and the

specific function of certain cations in alcoholic fermentation. Biochem.
Jour. 11:64-70. 1917.

- Hawxtns, Lon A., The effect of certain. chlorides singly and combined

in pairs on the activity of malt diastase. Bot. Gaz. 55:265-285. 1913.
Iwanorr, L., Zur Frage nach der Oxydation der oceania des
Zymins hee Atmungsprozess. Biochem. Zeit. 29:347-349

Kayser, M. E., Influence des nitrates sur les ferments ic Coiipt:
Rend. 151: 816-817. IgIo.

Kraysitt, Henry R., Effect of some alkali salts upon fire-holding capacity
of tobacco. Bot. Gaz. 64:42-56. 1917.

236 BOTANICAL GAZETTE [MARCH

22. Kiser, F., Uber die Einwirkung verschiedener chemischer Stoffe auf

die oe des Mundspeichels. Archiv. fiir die gesammte Physiologie

76: 276-305. 1899.

LISBONNE, Mar CEL, Influence des chlorures et des phosphates sur la

saccharification de l’amidon demineralise par les eee salivaire et

eo Rang Compt. Rend. Soc. Biol. 70:207—20

24. LOEVENHART, A. S., and PrErrce, G., The inhibiting oo * sodium
fluoride on action of lipase. Jour. Biol. Chem. 2:397-413. 1907.

25. NASSE, OrTo, Untersuchungen iiber die ungenformten Fermente. Paige
Archiv. 11:138-166. 1875.

26. Poropko, T., Zur Kenntnis der pflanzlichen Oxydasen. Beih. Bot.
Centralbl. 16:1-10. 1904.

27. REED, G. B., The relation of oxidase reactions to changes in hydrogen ion
concentration. Jour. Biol. Chem. 27:299-302. 10916.

28. Rose, D. H., Blister canker of apple trees: a physiological and chemical
study. Hor GAZ. 67: 105-146. I919.

29. SCHREINER, O., and SULLIVAN, oe X., Concurrent oxidation and reduc-
tion by roots. Bor. Gaz. 51:2

30. TERROINE, E. F., Zur Geant ee Fetispalting durch Pankreassaft.
Biochem. Zeit. 23: he: IgI0

31. WOHLGEMUTH, J., ——e iiber die A-aups L. Die tierischen

Sponges Biochem. Zeitschr. 9: 10-43.

- Worrr, M. J., Sur quelques sees sees des oxydases de Russula

déllea Compt. Rend. 148: 500-502. 1909.

ge LESKI, W., and REI EINHARD, A, Zur Frage der Wirkung der Salze auf

Biochem. Zeitschr.

‘)
S

we
1)

w
Bs:

o

27: 450-473. IgIo.

PIT- CLOSENG MEMBRANE IN OPHIOGLOSSACEAE
GERTRUDE WRIGHT
(WITH PLATES XI, XII AND SIX FIGURES)

The members of the Ophioglossaceae, an isolated family of un-
certain origin, are forms with a few large leaves, simple to decom-
pound, and short, slow growing, underground stems, vertical,
oblique, or horizontal in position, with crowded fleshy roots. The.
leaves, which are divided into sterile and fertile lobes, bear on the
latter homosporous sporangia.

Of the three widely distributed genera, Helminthostachys, a
monotypic genus, is the most restricted, occurring throughout
tropical Asia to North Australia and New Caledonia. Ophio-
glossum is represented by about 30 species growing under various
conditions of moisture and shade in the temperate and tropical
zones of both the Eastern and Western hemispheres. Botrychium,
with nearly as many species, is world wide in its distribution, but
is confined chiefly to the temperate regions.

The forms considered in this paper are Helminthostachys zey-
lanica, Ophioglossum vulgatum, the only species of the genus native
to Canada, and Botrychium obliquum, one of the 6 or 8 forms found
in Ontario.

The rhizome of Ophioglossum vulgatum consists of a large,
starch-filled cortex surrounding a siphonostele of endarch bundles
of primary wood. This cylinder may be broken by leaf gaps,
often so prolonged as to overlap, producing a circle of bundles.
Fig. 1 shows several such bundles, one, beside an outgoing root,
starting on its way through the cortex to the petiole. There is
no endodermis in the mature plant, and the pith is directly con-
tinuous with the cortex through the large leaf gaps.

Helminthostachys, whose rhizome is horizontal and dorsiventral,
presents a slightly different appearance in cross-section. Fig. 2
shows its broad woody cylinder solid on the lower side, broken
237] [Botanical Gazette, vol. 69

238 BOTANICAL GAZETTE * [maRcH

on the upper right by a relatively small leaf gap beside an out-
going leaf trace. The wood is entirely primary, with groups of
parenchyma scattered throughout it. The mesarch structure of
the bundles is not evident here, but may be demonstrated by
means of longitudinal sections. The large-celled, winding endo-
dermis is, unfortunately, too faintly stained to show clearly i in the
figure.’ According to FARMER and FREEMAN (4), there is in this
form cork formation confined to the upper surface and originating
at the bases of the cast-off leaves.

The most extraordinary member of the group in regard to its
wood structure, however, is undoubtedly Botrychium. In this
form there occurs a well developed cylinder of secondary
wood, as well as a definite cork layer. The stem shown in trans-
verse section (fig. 3) illustrates this. The woody cylinder sur-
rounding a rather large starchy pith is solid with the exception of
small leaf gaps, one of which appears in the lower part of the figure
to the left of a horizontal root. The wood, which is composed
of tracheids of irregular size, is traversed by numerous uniseriate
medullary rays of slightly radially elongated parenchyma. The
few and inconspicuous primary bundles are endarch. The peri-
‘cycle consists of several rows of parenchyma, and is surrounded
by an endodermis, frequently multiple. A rather large cortex,
also utilized in the storage of starch, is bounded by cork which is
visible in the upper right-hand corner of the figure.

The roots of the three genera show no secondary wood of any
account. Boop e (2) has described the addition of a few tracheids
at the base of the old roots of Ophioglossum vulgatum and Bo-
trychium Lunaria, but the later formed parts show only typically
primary bundles, in the case of the former genus monarch in
structure, and in the latter triarch or tetrarch (figs. 4, 5)- The
hexarch stele of the Helminthostachys root also shows only primary
arrangement (fig. 6).

The character of the wood elements themselves in the three
genera differs almost as much as their arrangement. Fig. 7 shows
the elements in the metaxylem of the root of O. vulgatum, stained
with Haidenhain’s iron-haematoxylin and safranin. They do not
differ from —- of the stem, hence they represent the general

1920] WRIGHT—PIT-CLOSING MEMBRANE 239

condition, pitting of the bordered scalariform type. With this
stain the primary wall shows broad and black through the sec-
ondary, dividing the narrow red borders of adjacent pits. This is
most apparent in the upper half of the tracheid to the left, where
the scalariform openings are uniseriate, extending from side to
side of the tracheid. In the lower half of the tracheid the primary
wall has not been cut. The pit borders are more or less clear,
also, about the middle of the tracheid to the right where the pits
aré small, eval, and biseriate. A combination of silver nitrate
solution and ammonia, used with a counter stain of methylene
blue, demarked these borders most clearly, but, unfortunately, did
not lend itself to photography.

_ On the other hand, the metaxylem of Helminthostachys and
the metaxylem and secondary wood of Botrychium exhibit a much
greater differentiation. The tracheids, as seen in longitudinal
section, are irregular and frequently nodular in appearance, with
pitting distributed equally on their radial and tangential walls.
The section illustrated in fig. 14 is from the rhizome of B. obliquum,
cut tangentially and stained with haematoxylin and safranin. The
tracheids are irregular in size and position, and interspersed with
uniseriate medullary rays. The central tracheid shows the typi-
cal pitting of the secondary wall. The uniseriate and biseriate
pits are large, round to oval in shape, with a centrally placed
round pore. The small shaded area surrounding the pore is ligni-
fied.‘ In the tracheids to right and left is depicted a feature
characteristic of both Botrychium and Helminthostachys, a ter-
tiary wall of lignin. About the center of the tracheid to the left
this layer appears as reticulately arranged bars lying over the
pitted secondary wall. Above the center the plane of section is
lower, exposing only the secondary wall; below the center it is
through the lumen of the tracheid, and consequently the tertiary
layer is seen in section. In the tracheid to the right, both the
“ tertiary and secondary walls have been cut only in section. Fig. 15,
also from B. obliquum, gives a sectional view of the pits with their
overlaid scalariform. The pit cavities are approximately twice as

‘In all the text figures lignification has been indicated by means of shading,
and a different focus or an obscure feature by dotted lines.

240 BOTANICAL GAZETTE [MARCH

long as broad, and rounded at the ends. The spools between,
forming their borders, show a fairly thick, secondary, unlignified
wall, ridged in most cases by one to two lignified (shaded) bars.
The areas between the pits are small, and the primary wall which
traverses them has, frequently, at the edges of the pits, thickenings

Fic. 14.—Botrychium obliquum: tangential section of the rhizome showing
pitting; 600.

similar to bars of Sanio. These are shown on the last four spools
‘toward the top of the figure.

Fig. 10 shows the stem wood of Helminthostachys to be fairly
similar to that of Botrychium, as seen in figs. 14 and 15. To the
right of the center the walls of two adjacent tracheids have been
-cutinsection. The left-hand wall is composed of only the secondary
layer, which is characteristically thinner than in Botrychium, that
to the right, of tertiary bars as well. The reticulate arrangement of
these bars may be seen in the tracheid to the left of the center.
The first-formed elements of the metaxylem of both Helmintho-
stachys and Botrychiwm show less of a tertiary layer than the later

1920] W RIGHT—PIT-CLOSING MEMBRANE 241

formed ones figured here. The scalariform bars in the former
are fine and rather far apart, in the latter broader and joined in
such a way as to produce the reticulate effect of fig. to.

In both Botrychium and Helminthostachys the tracheids of the
root wood, although slightly smaller and more regular than those
of the stem, resemble these very closely. There is, perhaps, a
greater amount of open scalariform tertiary thickening than in the
stem and less of the broad, close formation. The petiole wood
of both forms is also a likeness in miniature of that of the stem,
particularly of the first-formed elements of the primary metaxylem
of the latter. Frequently, however, the pit pores in Helmintho-
stachys petiole are long and oblique rather than round.

The presence or absence of a pit-closing membrane in the Ophio-
glossaceae, as in all the vascular cryptogams, has been a matter
of dispute. Russow (7), in illustrating his article of 1872, ex-
pressed the prevailing view of the anatomists of his time with
regard to the vascular cryptogams in general, when he showed no
membrane in the pits of either the side or the end walls of Bo-
irychium: It was in the following year that Santo, working with
Pinus sylvestris, demonstrated beyond a doubt the presence, in
the mature condition in that form, not only of a membrane but
also of a torus. From that time the pendulum of opinion began
to swing in the opposite direction. In response to the stimulus of
SANIO’s discovery, evidence has steadily accumulated that the
membrane in the vascular cryptogams remains in the pits of the
mature wood, not only in the side walls of the elements but, with
few exceptions, in the end walls as well. In 1908, however, this
view was challenged by GwyNNE-VAUGHAN (5). In returning to
the idea of the earliest investigators, that the membrane disappears
through resorption in the mature wood, the author distinguishes
two types of ferns, represented by Pieris and Osmunda respectively.
Ferns of the Pieris type, he claims, lose their limiting membrane
only from the pit cavities, while those of the Osmunda type lose
it also from between the walls of adjacent tracheids in the region
between the pits. Gwynne-VaucHAN describes a further modi-
fication of this type which, however, need not be discus
here, as he classes the Ophioglossaceae with ferns of the Pieris

242 BOTANICAL GAZETTE {MARCH

type. As far as the longitudinal walls are concerned, the
opposite view, that of the persistence of the membrane in the pits,
was upheld by Hatrr (6) for “all the vascular cryptogams.” He
demonstrated by physical and microchemical means the presence of
a limiting membrane in both the side and end walls of a large
number of ferns. Hatrt’s work was verified in the following year
by Miss Bancrort (1), then a research scholar in the University
College of Nottingham. Judging from her very lucid paper and
my own results with members of this group, I should think that
Hatrr had shown the “real’’ nature of the elements in the ferns.
Comprehensive as is his work, however, his statement is more sO,
for no mention is made of a study of any member of the Ophio-
glossaceae. Miss BANcrort, also, in corroborating his work, omits
this family.

Fig. 16, a drawing from the rhizome of Ophioglossum vulgatum,
shows the typical membrane in that form. In sections stained
with silver nitrate and ammonia and counterstained with methyl-
ene blue, the open scalariform pits, with their narrow, pale greenish-
blue borders, are traversed by a uniform pale brown membrane.
Fig. 17 illustrates the same condition in the root. Here haema-
toxylin accentuates the broad primary wall within the spools, and
stains only faintly the membrane in the pit. The latter, indeed,
often appears to be somewhat lignified, taking to a certain extent
the red stain of the lignified pit borders. The petiole as it leaves
the rhizome exhibits a similar type of membrane. |
It was with the greatest difficulty that the membrane in Hel-
_minthostachys was stained sufficiently for clear demonstration.
After prolonged staining with the ordinary haematoxylin and
safranin solutions, it remained so vague that its presence only, but
not its form, could be ascertained. The latter was finally revealed
by a stain consisting of malachite green, Martius’ gelb, and acid
fuchsin, originally used by Dr. PIaANEzE for cancer tissue. The
stain was recommended by R. E. VaucHAN (Ann. Mo. Bot. Gard.
_ May, 1914) as a differential stain for fungus and host cells.

Fig. 18 shows the condition in the rhizome. The lignified
(shaded) areas appear bright green, bounding the red of the un-
lignified secondary walls, which in turn bound the more deeply

1920] WRIGHT—PIT-CLOSING MEMBRANE 243

stained red primary wall. In the pits, the unlignified membrane,
a pale red, assumes the form of a long spindle- -shaped terus. Fig. 8
is from the adult metaxylem of the root, and shows the torus
lying across the space where the walls of adjacent tracheids have
been torn apart in sectioning. A slight thickening was found
also in the first-formed elements of the metaxylem. The tracheids

Fic. 15 Fic. 17 Fic. 18

Fics. 15-18.—Fig. 15, Botrychium obliquum: radial section of the rhizome show-
ing pitting and torus; — g. 16, Ophioglossum vulgatum: rhizome showing pit
membrane; goo; fi = libiemonnan vulgatum: root in cortex showing membrane;
Xgoo; fig. 18, Hvaiasianies zeylanica: longitudinal section of rhizome showing
torus; Xgoo.

of the petiole in longitudinal section, however, show a fine uniform
membrane with only occasionally a slight thinning toward the
edges of the pit.

In Botrychium two types of torus occur. The most common
type is that seen in figs. 9 and 15, a long, slender, and rather vari-
able spindle. This is found in the mature wood of the stem, the
root, and the leaf trace in the cortex. In the last region the mem-
brane varies from a spindle to a uniform line, as seen in transverse
Section in fig. 11. The arrow in a tracheid to the right of the
center points to a fairly thick membrane of the uniform type.

244 BOTANICAL GAZETTE ’ [MARCH

Fig. 12 shows a number of the spindle-shaped ones at a higher
magnification. The pit pores have been outlined for greater
clearness. The second type of torus occurs in the immature wood
of the stem and occasionally in the root. Fig. 19 shows a trans-
verse section from the cambial region of a young rhizome of B.
obliquum. The tracheids are only slightly lignified, some still
showing the contents. Here the torus is a short oval structure as

Fic. 19.—Botrychium obliquum: transverse section of young rhizome, at cam-
bium showing torus and double membrane; 600

long as, or slightly longer than, the pore of the pit, and connected
to its edges by a fine membrane.

This section (fig. 19) also illustrates a feature which I have
observed in other forms, that is, the double nature of the membrane.
In the pit of the tracheid at the left-hand lower corner the mem-
brane is of a double character. The tracheid lies against a paren-
chyma cell of the ray, and only the half of the membrane next to
the wood cell has been thickened, while that lying next to the ray
cell remains uniform. The same double nature and plano-convex
thickening of the membrane are shown in the third cell to the
right. Here a tracheid, as yet unlignified and filled with contents,
is adjacent to one which is more advanced in development, and
the thickening occurs only on the side of the latter.

1920] W RIGHT—PIT-CLOSING MEMBRANE 245

A peculiar condition is occasionally met with in the stem. The
tracheids are more or less discolored when cut, and stain in a
peculiar manner. With Pianeze’s stain the membrane becomes
yellow. It is usually uniform in thickness, but swollen, occasion-
ally almost entirely filling the pit (fig. 13).

In the petiole of Botrychium, as in that of Hieliisiaboaihye a
uniform membrane prevails. With the exception of the petiole,
therefore, and peculiar unnatural spots in the stem, the typical
pit membrane in Botrychium has a torus.

Thus the only torus I have found among the cryptogams
occurs in forms -whose pits are broad-bordered and circular or
oval in shape. STRASBURGER (8) makes the statement that a
torus occurs in Pleris aquilina, but he neither enlarges on the
statement nor illustrates it. DEBAry (3) describes and pictures
for Pleris an almost imperceptible one-sided swelling of the mem-
brane, lying to one side of the pit and acting, he states, as a lid
to the pit pore. I have searched in vain for such a torus. Fre-
quently the membrane may have a “kink’’ toward the pit pore
simulating the appearance of a torus, but both its edges follow

€ curve to an equal extent, thus precluding the possibility of a
thickening at that point. In Pteris the membrane in the pits
between tracheid and tracheid invariably remains uniform in
thickness. As has been shown in Botrychium, a plano-convex
torus such as DEBAry describes may occur in the pits of a tracheid
where it touches a ray cell. In Pteris, however, the membrane
€ven in this region remains consistently uniform. Eguisetum,
Psilotum, and Isoetes, forms with narrow-bordered pits of the
scalariform type, and a number of ferns (including Ophioglossum),
with the same type of pitting, all show a definitely uniform mem-
brane. In Helminthostachys and Botrychiium, whose pits are
circular, broad-bordered, and round-pored, there is developed a
definite torus. Although this suggests a possible relation of the
torus to the form of the pit, the question of its relationship, whether
structural, ecological, or phylogenetic, is one on which it is hoped
more light may be thrown after a study of the nature and occur-
rence of the torus in the other groups of the plant kingdom. It is
interesting to note, however, that the form of the torus in Botrychium

246 BOTANICAL GAZETTE [MARCH

and Helminthostachys, whose pitting is strikingly similar to that of
the seed plants, resembles closely the type I have found in the lower
gymnosperms, in Ginkgo me the araucarians, forms which are to
be described later.

To Professor R. B. THomson, under whose direction this
work has been carried on, is due my grateful acknowledgment of
his invaluable assistance andadvice. I am indebted also to both
Professor THoMsoN and Professor J. H. FAuLt for material, some
of which was obtained originally through the kindness of the
Director of the Royal Botanic Gardens, Kew.

UNIVERSITY OF TORONTO

LITERATURE CITED

x. Bancrort, N., On the xylem elements of the Pteridophyta. Ann. Botany
25:745-758. Igrt.
2. Boone, L. A., On some points in the anatomy of the Ophioglossaceae.
Ann. Botany 13:377-394. 18
3- DeBary, A., Comparative anatomy of the Phanerogams and Ferns, pp. 161
-162. 1884
ARMER, J. B., and Freeman, W. G., On the structure and affinities of
ltalbeciackes: zeylanica. Ann. Botany 13:421-445. 1899.
5. GWYNNE-VAUGHAN, D. T., On the real nature of the tracheae in ferns.
Ann. Botany 22:517-523. 1908.
6. Hatrt, F., Die Sc hliceahait der Hoftiipfel im Xylem der Gefaszkrypto-
gamen. Dissertation: IgIo
7. Russow, E., Vergleichende Untersuchungen. Mem. Acad. Imp. Sci. Saint
Petersbourg 19:1-207. 1872.
8. STRASBURGER, E., Das Botanische Practicum, p. 249. 1897.

EXPLANATION OF PLATES XI, XII

- I—Ophioglossum vulgatum: transverse section of rhizome; X 50-
. 2.—Helminthostachys zeylanica: transverse section of rhizome; X35-
. 3:—Botrychium virginianum: transverse section of rhizome; X*49-

. 6.—Helminthostachys zeylanica: root, transverse section; X14
Fic. 7.—Ophioglossum vulgatum: metaxylem of root showing pitting; ;

Sd

PLATE XI

BOTANICAL GAZETTE, LXIX

L, A sa
Y 8. ty ease

igs hee
Sate esas
os

e

Bie 4-6 Ogres nis Ge,
Rade ie, Hoes a 4 mg = NY Sg
athe ee Wee 2
~ oe % 742 OT ee et rae 04 &,
OMe WE, Fae seule Cewoti
ee, eS '

4
+ a? ee

s
.
ag @
3:
Af
i,
di
2
:
LY y
ess
a,

os ‘foF
e vq @

*

Sie
Kea T

WRIGHT on OPHIOGLOSSACEAE

BOTANICAL GAZETTE, LXIX PLATE XII

WRIGHT on OPHIOGLOSSACEAE

1920] WRIGHT—PIT-CLOSING MEMBRANE 247
Fic. 8.—Helminthostachys zeylanica: metaxylem of root showing torus;

00.

Fic. 9.—Botrychium obliquum: rhizome, tangential section showing
torus; 735.

1G. 10.—Helminthostachys szeylanica: rhizome, longitudinal section;

X825.

Fic. 11.—Botrychium obliguum: transverse section of leaf trace in cor-
tezs: A425.

Fic. 12.—Botrychium obliquum: part of fig. 11 more highly magnified;
X 875.

Fic. 13.—Botrychium obliquum: tangential section of rhizome showing
thickened membrane; X 525.

~

°

DOTHIDIACEOUS AND OTHER PORTO RICAN FUNGI
F. L. STEVENS

(WITH PLATES XIII, XIV AND THREE FIGURES)

The following fungi were collected by the author in Porto Rico,
and specimens are deposited in the herbarium of the University
of Illinois, and of the New York Botanical Garden. The limitations
accepted for the Dothidiaceous genera are those of THEISSEN
and Sypow,’ which seem to be well founded and wholly tenable.

Dothideales
DOTHIDEACEAE 4

AUERSWALDIA CECROPIAE P. Henn. (figs. 4, 5).

On Cecropia peltata: El Alto de le Bandera, 9043; Mayaguez, 3931;
Maricao, 8965; Rio Arecibo, 7798; Florida Adentro, 7756, 2475; Jayuya,
361; Afiasco, 3581; Utuado, 6064.

This fungus, as the Hihibes of collections shows, is abundant in Porto
Rico. From descriptions it seems to be the one just named. It is very
variable in habit, especially with age, and there is some doubt as to its generic
position. In young specimens there is no stroma, and the fungus appears
Sphaeriaceous. In older specimens the stroma is well developed, and the
fungus is clearly Dothidiaceous. No colored spores were seen, and the fungus
to all appearances is really a Phyllachorella. Type material of A. Cecropiae
P. Henn. and Physalospora Cecropiae Rehm are needed before a satisfactory
decision can be made.

Uleodothis Pteridis, sp. nov. (figs. 6, 7).—Spots tan-colored,
dead, 3-5 mm. across. Stromata black, rugose with perithecia,
I-2 mm. across, conspicuous above, less so below, slightly raised
above the leaf surface, orginating sub-epidermally but eventually
occupying the whole mesophyll, the upper surface rough and
raised, without clypeus, and remaining covered by fragments of
the epidermis. Hyphae of the stroma of general parallel arrange-
ment. Loculi many, about 1oom in diameter, globular. Asc

tAnn. Mycol. 13:149. 1915.
Botanical Gazette, vol. 69] , [248

1920] _ STEVENS—PORTO RICAN FUNGI 249

numerous, 65X14 u, cylindrical, 4-spored. Paraphyses few, incon-
spicuous, fine, filamentous. Spores hyaline, 2-celled, oblong,
EPSON, ASS Be:

On Pleridium caudatum, Maricao, 4814 (type), 167.

This fungus agrees somewhat closely with Dothidella pteridophila Speg.,
but differs essentially in that it has paraphyses, and the asci are 4-spored.
It differs from Uleodothis, as described, in having 4-spored asci, but it does
not seem wise to found a new genus merely on this character.

ren

te gt
aS Nene aa, et 2s
AAA L we ad &

Fic. 1.—Structure of stroma and arrangement of locules

Dothidella portoricensis, sp. nov. (figs. 8, 9; text fig. 1).—Spots
linear, o. 5-1 3-4 mm., amphigenous, definite. Stromata linear,
entirely occupying the spots, raised above the leaf surface about
704. Perithecial cavities in about 5 rows, nearly globular, about
70m in diameter. Paraphyses none. Asci numerous, cylindrical,
54X10, 8-spored. Spores hyaline to dilute smoky, 1-septate,
17X3.5 yu. :

250 BOTANICAL GAZETTE [MARCH

On Gleichenia, Las Marias, 3551, x.62 (type).

The stromata differ essentially in shape from those of D. pteridophila
Speg. (fig. 1).

Dothidella flava, sp. nov. (text figs. 2, 3).—Stromata pale to
yellow, circular when young, linear when old; when mature,
1600 4 long by 270 wide, subepidermal, later erumpent, rising

to considerable height above the leaf surface. Perithecial locules

YPRSS
")S Ae =)h
QO

oA

Sa AN
RAWAM

iG

=

2B
aS
ey

\W
2)

Fic. 3

Fics. 2, 3.—Cross and long sections showing arrangement and shape of peri-
thecia and pycnidia. '

globular, 60-70 » in diameter, arranged in one or two rows in the
stromata. Asci linear, 8-spored, 34-516. Spores hyaline,
2-celled, oblong, 3.514. Conidia filamentous, 40X1-.5#,
hyaline, borne in the same stromata with the perithecia and pre-
ceding them, and either free in an acervulus or in pycnidial locules
in the stroma.

On Lithachne pauciflora: Trujillo Alto, 9394, 7654; Mayaguez, 1062, 7432)
Florida Adentro, 7665 (type), 7650.

1920] STEVENS—PORTO RICAN FUNGI 251

This fungus is particularly interesting. To the naked eye it is like a rust.
Superficial microscopic examination shows circular conidial sori which on
casual observation might pass as a Cylindrosporium. Intermingled with
the circular sori are many linear sori and stromata, all bearing the Septoria-
like conidia in great numbers. Microtome sections show that all development
is subepidermal. The first locule is conidiiferous, and is so thin-walled that
the wall might easily be overlooked. The sorus elongates, ruptures the
epidermis, and in section takes on the appearance shown in text fig. 3. At
about this period perithecial locules appear with asci and spores. Their
walls are indistinguishable from the surrounding stroma, and the whole struc-
ture is truly Dothideaceous. The stromata are frequently overgrown by a
Helminthosporium. Following THEISSEN and Sypow, it belongs to the Dothide-
aceae, falling in the genus Dothidella. To many it may appear more reason-
able to put it in the Hypocreales on account of its color; but it appears to me
to show much closer relationship with the Dothideaceae, notwithstanding
its pale color.

PHYLLACHORACEAE

TRABUTIA RANDIAE (Rehm.) Th. and Syd.

On Randia aculeata, Cabo Rojo, 6455.

This fungus is clearly a Trabutia with strictly subcuticular stroma, and
as it agrees well with the published description of T. Randiae, it is in all proba-
bility that species.

SCIRRHIINEAE —

Catacauma Ocoteae, sp. nov.—Spots irregularly circular,
©.5-1 cm. or more in diameter, visible from above or below on
dead, tan-colored tissue, border indefinite. Stromata circular,
numerous, scattered throughout the spot, plane above, strongly
rounded below, 1-1. 5 mm. in diameter, between the lower epider-
mis and the mesophyll. Clypeus hypophyllous, rarely epiphyllous,
extending slightly beyond the perithecia, very thick (60-110 4).
Locules several, large (about 300 u in diameter), irregular. Asci
4-8-spored, 85-1027 u long, slender, with long sterile base. Spore
1-celled, hyaline, oblong, 14-20X3.5. Paraphyses filiform.

On Ocotea leucoxylon, Monte Alegrillo, 4725 (type), 732, 1347

Entirely distinct from Phyllachora ocoteicola, although often upon the
same leaf,

Catacauma palmicola, sp. nov. (figs. 1o-12).—Stromata con-
Spicuous above, few below, black, shining, oval, 1-6X1-3 mm.,

252 BOTANICAL GAZETTE [MARCH

with rounded surface, scattered and separate or clustered and
confluent. Diseased area extending through the leaf, brown
below. Stroma developing between epidermis and palisade cells,
often 300 thick. Locules irregular in shape, often 500-6004
wide, basal layer hyaline, thin, lateral walls brown, thick; clypeus
black, 60-100 thick. Asci numerous, 8-spored, saccate, thin-
~ walled. Spores inordinate, cylindrical, 28-43X12-14 p, hyaline,
continuous.
On Thrinax ponceana, Vega Baja, 7716 (type).

CATACAUMA URBANIANUM (A. and H.) Th. and Syd. (fig. 13).

On Pg caanee Krugii: El Yunque, 8243; Maricao, 3677, 374°

What o be the same fungus, although usually hypophyllous
and showing a ee arrangement of stromata, occurs on an unknown
Myrtaceous host, no. 5766, San German. Another specimen from Monte
Alegrillo, 4526, shows the characteristic acervuli and spores, but is mainly
conidial. The Septoria-like conidia are borne in very large cavities in the
stromata. The ascospores in these specimens are slightly longer (17-20 »)
and slightly thinner (5 «) than called for by description.

Catacaumella Gouaniae, sp. nov. (figs. 14, 15).—Mainly epi-
phyllous, rarely hypophyllous. Spots barely extceding the stro-
mata, hardly visible below. Stromata abundant, roughly circular,
2-3 mm. in diameter, raised, wrinkled, shining black, developing
between the epidermis and the palisade cells and made up of
parallel cells perpendicular to the leaf surface. Loculi large, flat,
500 4. wide, about 150-160 mw deep, single or few in each stroma.
Ostiole very large and distinct. Asci thin-walled, irregular,
8-spored, 61-68X10-11 yu, inordinate. Spores hyaline, - I- -celled,
ovoid or pyriform, irregular, 14-20X10, Paraphyses none.

On Gouania polygana: Mayaguez, 3923 (type), 1049; Salinas, 6798;
Dos Bocas, 6007, 8092; Maricao, 8953; on Gouania lupuloides, Arecibo-Lares
toad, 7230.

The last specimen shows the stromata smaller and more abundant upoR
the lower surface than is the case with the other specimens.

Phaeodothopsis Eupatorii, sp. nov. (figs. 16, 17).—Spot not
exceeding the clypeus. Stromata numerous, circular, 1-4 mm.
in diameter, black, rough with perithecia, almost exclusively
epiphyllous; developing first in the epidermis, producing am

®

1920] STEVENS—PORTO RICAN FUNGI 253

extensive clypeus, then developing the stromata between this clypeus
and the palisade cells. Loculi globular or lenticulate, 100-250 u
in diameter, 80 high, by pressure sometimes pushing into the
mesophyll. Asci about 110X174, cylindrical, 8-spored, inordinate.
Spores 20X7 uw, 1-septate about one-third the distance from one
end, brown when mature. Paraphyses filamentous, branching.

On Eupatorium portoricense, Dos Bocas below Utuado, 6866 (type), 6034,
6830, 6437, 6861, 6032, 6537.

The clypeus is strictly epidermal, and under it very numerous loculi
develop, each with an ostiole reaching through the clypeus. The occasional
pressing of the perithecia into the mesophyll sometimes gives this the appear-
ance of closer relationship to the Phyllachorineae, but its relationship is clearly
with the Scirrhiineae.

Halstedia, gen. nov.—Asci borne in a locule in a superficial
stroma.

Type H. Portoricensis. Named in honor of Byron D. Hatstep.

Halstedia portoricensis, sp. nov. (figs. 18, 19).—Stromata
amphigenous but more abundant and larger above, densely black,
I-4 mm. in diameter, flat, with surface in the older parts corrugated,
or sometimes raised in the center, strictly superficial, non-radiate.
Perithecia up to 400 p in diameter, 160 u from base to top, internal
measurements. Asci 8-spored, 68-8514, cylindrical. Spores
oval,-continuous, hyaline or pale straw-colored, oe 10 yu.

On Sideroxylon a Quebradillos, 9239 (type

The fungus co s of a densely black stroma ii in the center is
nearly 200 w in ‘uae thinning at the edges to the thickness of the mycelium.
The stroma is flat-topped, the bulging due to the development of the perithe-
cium usually resulting in a downward thrust and displacement of the leaf
tather than of the upper layer of the stroma (fig. 16). In some instances the
reverse is true, with an upward bulging. Closest search failed to reveal any
evidence of penetration of the fungus through the epidermis, or of any mycelium
or signs of disease in any of the host cells. There is no ostiole, and the perithe-
cium is poorly developed, if indeed it is more than a locule in the stroma. The
fungus shows close kinship with the Dothideales, but cannot be placed in any
of the families of that order as characterized by THEISSEN and Sypow. It
differs from typical Perisporiaceae in the absence of a clearly developed perithe-
cium and in possessing a stroma. It forms an interesting transition form
ata these two groups, and may for the present be regarded as Perisporia-
ceou

254 BOTANICAL GAZETTE [MARCH
Perisporiales
PERISPORIACEAE

Dimerina monenses, sp. nov. (fig. 20).—Epiphyllous, rarely
hypophyllous, diffuse over the leaf surface. Mycelium superficial,
scant, dark, irregular, 3 4 thick with thinner side branches. No
hyphopodia, perithecia rough, irregularly spherical, 45-60 m in
diameter, without ostiole, arranged in close clusters of 10 or more
on a close dark subicle. Clusters 150-300 in diameter. Asci
numerous, elliptical, 3417 u, obtuse, 8-spored. Spores inordinate,
hyaline or very pale-smoky, 13-16 3 uw, obtuse, 2-celled.

On Jacquinia barbasco, Mona Island, 6087.

While the spores and asci agree well in size with those of Dimerina eutricha
and D. negeriana, our species does not agree with these forms in other characters.

Agreement as to asci and spores is close with Asterina paupercula E. and E.,
but our perithecium is not that of an Asterina.

HYSTERIINEAE

_Gloniella rubra, sp. nov. (fig. 21).—Perithecia oblong, scattered,
numerous, epiphyllous, black, 600-1500 180-250 wu, opening by
one or more longitudinal clefts; the perithecial contents thus
exposed are red (near color no. 13 of Saccardo’s scale). Asci long-
cylindrical, very crooked, especially at the tip, 8-spored, 85-92 10
u, inordinate. Paraphyses numerous, filiform, long. Spores hya-
line or very faintly tinted, 1-3, mostly 3-septate, fusoid, 23-26X 3 M-

On Arthrostylidium multispicatum Pilg., El Alto de la Bandera, 4363
(type).

This species is somewhat like G. pusilla Sacc., but differs from it in its
carbonaceous perithecium, red contents, curved asci, etc.

PLEOSPORACEAE
PuysaLospora Hoyakg, v. Hohn. (fig. 22).

On Ficus, Mona Island, 6234, 616:

This very pretty form I refer ix some hesitancy to the pension species.
The spores in my specimen are uniseriate, and are considerably narrower than
the description of von. HoHNEL calls for. P. elasticae Koord. is close kin, but
differs in the rounded spores. Pycnidia are present, bearing slender filamentous
spores, 7 XI p.

1920] STEVENS—PORTO RICAN FUNGI 255

MYCOSPHAERELLACEAE

Guignardia Justiciae, sp. nov. (figs. 23, 24).—Diseased spot
indefinite, finally yellowish and pale, rather evenly beset with
perithecia, 1-2 mm. distant from each other. Perithecium
globose, completely imbedded in the leaf, 265 u in diameter and
depth, its wall dark, several cells (34 u) thick. Host tissue sur-
rounding the perithecium hypertrophied to a distance of about
125m in every direction from the perithecium. The resulting
“gall” is visible from either side of the leaf, and has the superficial
appearance of a stroma with a single central perithecium. The
ostiole develops late. Paraphyses none. Asci clavate, usually
with a long stipe; body of ascus 17-2061 u; total length, includ-
ing stipe, 125. Spores 8, inordinate, hyaline, 1-celled, oval,
Q-10X 18 yw.

‘On Justicia verticillaris: Maricao, 806 (type); El Yunque, 2839; El
Gigante, 8557; El Alto de la Bandera, 9046.

This fungus is noteworthy on account of the peculiar gall-like formation
surrounding each perithecium, the thick wall, and the peculiar long-stalked asci.

Guignardia Tetrazygiae, sp. nov.—Spots indefinite, irregular,
I-2cm. in diameter or occupying the whole leaf, tan-colored,
centers studded with the perithecia which are scattered evenly
and profusely over the affected areas. Perithecia black, con-
spicuous both above and below, about 160 in diameter, thick-
walled. Asci, sporiferous part oval, 45X27 », 8-spored, inordinate,
stipe long, slender, 30-60X4-5 u. Paraphyses none. Spores
t-celled, hyaline, oval, obtuse, 2410 u.

On 7 etrazygia sp.: San German, 4567 (type); Vega Alta, 4148.

This differs from Laestadia melastomalum (Lev.) Sacc. in the absence of

i. shape of asci, and other characters. The leaf spot is very charac-
teris

Guignardia Nectandrae, sp. nov.—Spots indefinite when
young, becoming definite as the host tissue dies, then angular,
2-6 mm. in diameter, showing from both sides of the leaf. Peri-
thecia opening on both sides of the leaf, more abundant below,
Scattered, located in the mesophyll but causing swelling of both
leaf surfaces. Perithecia thin-walled, pale, 70-854 in diameter,

256 BOTANICAL GAZETTE [MARCH

located deep in the mesophyll. Asci clavate, 100-115X20uyn,
8-spored. Spores hyaline, oval, 21-24X8-10y, 2-celled, septa
either in the middle or more frequently located near one end.
On Nectandra coriacea (?), Quebradillos, 4994 (t
This fungus is of very distinctive appearance upon the leaves, where the
erumpent perithecia so closely simulate a rust in appearance that the author
was led to place it with the rusts on mere casual examination

SPHAERIACEAE

Zignoella algaphila, sp. nov.—Mycelium fine, pale to brown,
twining around and penetrating its algal host and turning it brown.
Perithecia black, 90170-180, variously formed but usually
bottle-shaped, broadest a little above the base, with a prominent
beak about 24 uw in diameter and with the fibers arranged parallel
around the ostiole. Surface coarsely reticulate but not hairy;
basal portion appearing as though hairy due to adhering remnants
of mycelium. Asci numerous, 8-spored, cylindrical, 71X7#-
Paraphyses fine, threadlike. Spores hyaline, 3-septate, pointed
at each end, 17-21 X3.5 wu. :

On’ Cephaleuros virescens on Artocarpus ¢ incisa, Mayaguez, 51 (type).

The parasitic alga when alone on this host is yellow or often nearly colorless,
but when invaded by the Zignoella all the colonies take on a dark hue, giving
the whole leaf much the appearance of being mildly affected with sooty mold.
The genus Zignoella is large and composed mainly of wood-inhabiting sapro-
phytes. One is listed on Valsa, one on the thallus of Castagnia, and two species
(Z. enormis Pat. and Z. cubensis H. and Pat.) on the alga Stypocaule. These
thallus-inhabiting forms, however, are markedly different from the present
species.

Sphaeropsoidales

Phyllosticta bonduc, sp. nov.—Spots indefinite, ‘large, starting
usually at edge or apex and progressing over the whole leaflet.
Pycnidia numerous, black, scattered, ostiolate, about 160-190 #
in diameter. Wall about 17 thick, ostiole large, irregular.
Conidiophores simple, hyaline, arising from sides and base of
the pycnidium. Conidia hyaline, 1-celled, oblong, 21X4 mu, some-
what irregular in shape.

On Caesalpinia bonduc, Guanica, 360 (type).

This fungus is quite distinct from iar guanicensis.

UNIVERSITY ‘oF ILLINoIs

Ursana, ILLInots

*

BOTANICAL GAZETTE, LXIX PLATE XIII

STEVENS on FUNGI

BOTANICAL GAZETTE, LXIX PLATE XIV

STEVENS on FUNGI

1920] STEVENS—PORTO RICAN FUNGI 257

EXPLANATION OF PLATES XIII, XIV

Fics. 4, 5.—Auerswaldia Cecropiae P. Henn.: fig. 4, habit, showing, a, abun-
dant scattered young spots (no. 361); b, older infections each surrounded by
discolored spot (no. 9043); ¢, still older spots with much dead tissue (no. 9043);

g. 5, old, well-developed stroma completely occupying leaf from epidermis
to epidermis.

Fics. 6, 7.—Uleodothis Pteridis, sp. nov.: fig. 6, habit; fig. 7, stromata
occupying whole mesophyll with locules on both surfaces.

Fics. 8, 9.—Dothidella portoricensis, sp. nov.: fig. 8, habit, a leaf segment
(no. X62); fig. 9, cross-section of stroma. *

IGS. 10-12.—Catacauma palmicola, sp. nov.: fig. 10, habit; numerous
stromata on piece of palm leaf; fig. 11, young stroma and locules, showing that
it is strictly subcuticular; fig. 12, sectional view of mature stroma showing
3 locules.

Fic. 13. Sigur urbanianum (A. and H.) Th. and Syd., showing
eo No. 357

G. 14. Lee Gouaniae, sp. nov.: habit, stromata scattered
over sa
Fic. 15.—Catacaumella Goiaitae: sp. nov.: stroma in section, showing
that it is ee entirely above palisade cells.
Fics. 16, 17.—Phae seas eupatorii, sp. nov.: fig. 16, habit, showing
aims S different Fea (no. 6 ; fig. 17, stroma in cross-section
F , 19.—Halstedia Rees at sp. nov.: fig. 18, erneesl view of
ea on leat ; fig. 19, stroma in section, shombia depression of leaf by
growth of strom

Fic. 20. Dime erina monensis, sp. nov., showing habit.

Fic. 21.—Gloniella rubra, sp. nov., showing habit.

Fic. 22.—Physalospora Hoyae v. Hohn., showing habit.

IGS. 23, 24.—Guignardia Justiciae, sp. nov.: fig. 23, habit; fig. 24,
section through hypertrophied portion showing perithecium.

SPERMATOGENESIS IN BLASIA
LESTER W. SHARP
WITH PLATE XV
Introduction

The following brief account of spermatogenesis in Blasia pusilla
is based upon preparations made from a limited amount of material
collected near Chicago several years ago. The preparations,
which were originally made for use in classes, proved upon care-
ful examination to show with admirable clearness all stages included
in the last spermatogenous mitosis and the transformation of the
androcyte (spermatid) into the spermatozoid. Since the results
of the examination differ in two important points from those re-
ported by WoopBurN (12) in the only previous paper dealing with
these features in Blasia, they are here récorded. -

. _Description

The description will begin with the spermatogenous cells of
the penultimate generation, the androcyte mother cells, to use the
terminology of ALLEN (1). The cells of the earlier generations
(androgones) have been examined, and nothing which it is safe to
call centrosomes has been observed. Unfortunately, however,
the material did not show many androgone nuclei in division,
anaphases were present, but metaphases, where centrosomes are
usually most conspicuous if present at all, were not found. No
conclusive statement can be made, therefore, regarding the pres-
ence or absence of centrosomes in the androgones. :

In the androcyte mother cell, before the stage represented in
fig. 1, the cytoplasm has an almost homogeneous appearance, and
included in it are several granules or vaguely defined areas. In
some cells these granules, from 1 to 6 or more in a thin section, may
appear to be all alike; while in other cells one or two of them may
be more sharply defined and more deeply stained than the others.
It is possible that of these seyeral granules two survive as the |
Botanical Gazette, vol. 69] [258

1920] SHARP—SPERMATOGENESIS 259

centrosomes shown in fig. 1, after the manner of the ‘‘black gran-
ules” in the body cell of Dioon (CHAMBERLAIN 4). On the other
hand, it would be possible to select a series of cells illustrating the
divergence of daughter centrosomes arising by the division of one,
as in Equisetum (SHARP 8); or even to show the origin of the bodies
in question from the nucleus, as described by Witson (10) for
Airichum and Mnium. The writer, however, believes that the
evidence afforded by his material is insufficient to support any
of these hypotheses in the case of Blasia. The present descrip-
tion, therefore, will begin with a stage (fig. 1) at which the identity
of the centrosomes is unmistakable, the question of their origin
and earlier history being left an open one.

Two centrosomes, whatever may be their previous relation to
other cell granules, soon stand out with great distinctness as
intensely staining bodies near the cell membrane at opposite poles
of the androcyte mother cell (fig. 1). At this time the cell is still
rather square in section, since it has only begun to round off from
its neighbors, and the centrosomes commonly occupy the corners,
as shown in the figure. From each centrosome a conical group of
very faint fibers extends toward the nucleus, which is somewhat
flattened on the sides facing the centrosomes. While the nucleus
is undergoing the prophasic changes (fig. 2) these fibers become
more plainly visible, and when the nuclear membrane disappears
they become attached to the chromosomes and establish the
achromatic figure with the centrosomes at its poles.

It is at metaphase that the spindle is seen most clearly (fig. 3).
As noted by WoopBurn (12), it may lie either straight or obliquely
in the cell. Furthermore, the cells may round up and alter con-
siderably in shape while mitosis is in progress, so that although
the centrosomes may at first be situated near the corners of the
cell, all appearance of the diagonal division so characteristic of
many bryophytes may in many cases be lost by the time the meta-
phase and succeeding stages are reached (figs. 4, 5).

When the chromosomes reach the poles at the end of the ana-
phase (fig. 4), they usually come in contact with the centrosomes.
As a result the latter, which are very minute, are often difficult to
find at this stage. Careful search, however, reveals cells in which

260 BOTANICAL GAZETTE [MARCH

they stand out clearly a little apart from the chromosome groups.
From this time onward they become increasingly distinct. As
the membranes form about the reorganizing daughter nuclei at
telophase the centrosomes are left just outside in the cytoplasm
(fig. 5), and while cell division is being completed they move away
from the nucleus and take up positions nearer the cell membrane
(fig. 6).

The two androcytes (spermatids), between which no cell wall
is laid down, quickly round off from each other (fig. 7). In prob-
ably the majority of cases they are somewhat triangular in shape,
owing to the usual diagonal plane of the division which differen-
tiates them. In each androcyte the blepharoplast, as we may
call the centrosome in view of the function it performs in the cell
which it now occupies, enlarges considerably and becomes some-
what elongated.

A careful search has been made in the cytoplasm of the an-
drocytes for accessory structures corresponding to the “chroma-
toider Nebenkérper” (IkrNo 6) or “limosphere’’? (WILSON 10),
the “percnosome” and the “apical body’? (ALLEN 2) described
by other investigators of bryophyte spermatogenesis; but, as
WoopsvurN (12) also reports, nothing which can confidently be
regarded as such a body has been found. Occasionally there is
observed in the cytoplasm a-darker area, which, although it is
as a rule rather vague in outline (fig. 7, below and at left of nucleus
in each cell), may in certain cases be more definitely delimited
(fig. 9). A similar appearance is also often seen in the later stages
of spermatogenesis (figs. 15, 16, 18, 19). It may well be that we
are dealing here with a limosphere or other accessory body, but
without more trustworthy evidence for its constant presence and
regularity in behavior, at present it does not seem advisable to
attribute to this body any special significance in the case of Blasia.
The cytoplasm of the androcyte frequently contains a large vacuole,
which may or may not lie near the blepharoplast (fig. 8).

The blepharoplast now begins to undergo a series of trans-
formations which ultimately result in the formation of the cilia-
bearing thread of the spermatozoid. After elongating very
slightly, as previously notéd, the blepharoplast becomes constricted

1920] SHARP—SPERM ATOGENESIS 261

(fig. 10, upper cell) and divides by a process of simple fission into
two portions (fig. 10, lower cell). These two portions, or blepharo-
plast granules as they may be termed, often lie very close to-
gether, but in many cases they are so far apart that there can be
no doubt that the fission is complete. As a rule one of the gran-
ules at once begins to elongate, while the other remains relatively
unchanged, so that many cells show two bodies, one of them
round and the other comma-shaped, lying close together near the
cell membrane (fig. 11). At about this stage the granules usually
move closer to the nucleus. The comma-shaped granule con-
tinues to elongate (fig. 12) and divides again; whether the other
granule also divides or not is a difficult matter to determine. The
granules continue to multiply by fission (fig. 13) until several are
present in a row (figs. 14, 15); seven was the largest number
counted with certainty. The granules now appear less distinct
from one another; it seems that they gradually undergo a coales-
cence (figs. 14-16), but it may also be that some of the fissions are
incomplete, some of the granules therefore never being entirely
separate.

The nucleus at this time moves more closely against the beaded
blepharoplast (fig. 15) and begins to draw out into a point by the
side of the latter (fig. 16). Both nucleus and blepharoplast con-
tinue to elongate spirally, the association between them becoming
constantly more intimate (fig. 17). Fig. 18 represents a cell like
that of fig. 17 viewed from the direction indicated by the arrow;
it is here seen that the blepharoplast is applied along one edge
of the flattened point of the nucleus. As the transformation
continues the boundary between nucleus and_blepharoplast
gradually becomes indistinguishable (fig. 19). Even at this late
Stage the irregular outline of the blepharoplast is still evident;
the blepharoplast granules have not yet become so completely
coalesced that the thread which they form is smooth in outline.
The nucleus continues to elongate and condense, becoming
increasingly slender, while two cilia grow out from the blepharo-
plast, which projects beyond the nucleus at the anterior end.
The spermatozoid is now mature (fig. 20) and ready to escape
from the antheridium.

262 BOTANICAL GAZETTE [MARCH

Discussion

The two main points wherein this description disagrees with
that of WoopBuRN (12) are as follows. First, according to that
author there are no indications of centrosomes in the spermato-
genous mitoses, the blepharoplast first appearing as a cytoplasmic
differentiation in the androcyte. On the contrary, the present
writer finds that centrosomes are present at all stages of the last
mitosis, and that these persist as the blepharoplasts of the andro-
cytes. Second, WoopsuRN states that the blepharoplast in the
androcyte undergoes a simple elongation to form the cilia-bearing
thread, whereas the present writer sees it fragmenting to several
pieces which coalesce to form the thread somewhat after the man-
ner of the blepharoplasts of Equisetum and Marsilia (SHARP 8, 9).

It is not improbable that this disagreement is due in part to
actual differences in the two lots of material studied. Although
the single species of the genus, Blasia pusilla, was used in both
instances, a comparison will show that the cells described in the
present account are little more than half the size of those figured
by Woopsurn. Although it is possible, therefore, that the two
lots of material represent two varieties, too much weight should
not be placed upon a size difference, for it is known in certain
cases (Equisetum, SHARP 8) that androcytes and spermatozoids
often vary considerably in size in the same lot of material.

Lack of agreement as to the presence of centrosomes during
mitosis is perhaps not surprising. Because of their extreme
minuteness the centrosomes might easily be overlooked in the
stages previous to that at which Woopsurw first finds them, and
at which they enlarge and become really conspicuous for the first
time. With regard to the fragmentation of the blepharoplast, on
the other hand, it is more difficult to understand why material
actually the-same should be interpreted so differently. In the
writer’s material the process of fragmentation is shown with great
clearness; only occasionally is anything found in good prepa-
rations which might be interpreted as a uniformly elongating ble-
pharoplast. Moreover, in no case has a condition approaching
that shown in Woopspurn’s fig. rx been observed. The nucleus
becomes closely applied to the blepharoplast when the latter is in

1920] SHARP—SPERMATOGENESIS 263

the form of a short lumpy rod or series of granules, and at no time
does the blepharoplast have the form of a long slender thread free
from the nucleus as in WoopBuRn’s figure. The writer, therefore,
is inclined to attribute the disagreement for the most part to actual
differences in the material studied rather than to differences in
interpretation.

The phenomenon of fragmentation is probably the most inter-
esting feature of the blepharoplast of Blasia. In all previous
accounts of bryophyte spermatogenesis, including those of IkENo
(6) on Marchantia, W11son (10) on Pellia, Polytrichum, and Atri-
chum, WoopBURN (11, 12, 13) on several liverworts and Mnium,
Miss Biack (3) on Riccia, and ALLEN (2) on Polytrichum, the
blepharoplast is reported to elongate without breaking up into
smaller portions. ALLEN (2) states that “while the possibility of a
somewhat similar occurrence [fragmentation] is suggested by the
rather knotty appearance of the blepharoplast of Polytrichum when
it begins to elongate, there is no time when it is visibly resolved into
smaller bodies.” In Blasia, therefore, we have the only known
instance in bryophytes of such a fragmentation of the blepharo-
plast as occurs in Equisetum, Marsilia, and the cycads. :

Although fragmentation is in general a characteristic of the
blepharoplasts of the cycads, and only occasionally found in
pteridophytes (Equisetum and Marsilia), it is now evident that it
May occur in forms lower in the scale. Moreover, it is seen that
it is not, as might be supposed, merely a means by which large
blepharoplasts become transformed, for the blepharoplasts of
Equisetum and Marsilia, and especially those of Blasia, are very
small. Although the details of the process of fragmentation differ
in the various cases (by simple fission in Blasia and by vacuoliza-
tion in the other forms), it is scarcely to be doubted that the phe-
nomenon is a result of similar causes in all. In attempting to
find a possible historical reason for it, one is struck by the resem-
blance between the fission of the blepharoplast in Blasia (fig. 10)
and the division of an ordinary centrosome before mitosis. If the
blepharoplast actually represents a centrosome, as the writer (8)
believes the evidence indicates, it is at least possible that its fre-
quent fragmentation, in spite of the fact that in the more advanced.

264 BOTANICAL GAZETTE [MARCH

forms (cycads) this fragmentation becomes a very much modified
process, may be a manifestation of the power of division which is
one of the chief characteristics of centrosomes. According to this
interpretation the first fission of the blepharoplast of Blasia (fig. 10)
would correspond to the centrosome division which would normally
occur if another mitosis were to take place, and the further frag-
mentation would represent a further manifestation of the cen-
trosome’s power of division which may have been retained from
a time when more spermatozoids were produced from a mother
cell, and which has in some way become a feature of the develop-
ment of the cilia-bearing structures. In this way Blasia may shed
light upon the origin of the remarkable behavior of the cycad
blepharoplasts. :

To this idea, which presents itself as a suggestion and may
scarcely deserve to be proposed as a theory, there are obviously
many objections. Chief among these is the fact that fragmenta-
tion is most conspicuous in the blepharoplasts of the cycads, but
developed almost not at all in those of the bryophytes, which
would be expected to have retained in the manner of their elonga-

‘tion more evidences of a derivation from normal centrosome
division. It is possible, however, that the simple fission of the
blepharoplast as seen in Blasia ,was soon replaced in most
bryophytes and pteridophytes by uniform elongation without
fragmentation through the failure of the fission. to occur, aiter
the slight elongation normally preceding it (figs. 7-9), this
elongation then continuing to form the uniform cilia-bearing
thread. Fragmentation would thus be a retained feature in
Blasia, Equisetum, Marsilia, and the cycads, although the manner
in which it is accomplished in the higher forms (through a
complex process of vacuolization rather than simple fission)
would still be regarded as an advanced feature subsequently
evolved. Whether, therefore, the objection stated rules out the
suggested explanation or not can scarcely be decided in view of
the fact that the evidence at hand has been obtained from s0
few bryophytes and pteridophytes, comparatively speaking, and
especially in view of our lack of adequate knowledge of blepharo-
plast origin and behavior in the algae.

1920] SHARP—SPERMATOGENESIS 265

A further objection may be seen in the case of animal sper-
matogenesis, in which an undoubted centrosome elongates with-
out fragmentation as it performs its rédle in the development of
the motor structures. It is noteworthy, however, that cilia are
frequently seen growing from recently divided centrosomes in the
case of certain insect spermatocytes (HENNEGUY 5) in much the
same fashion that the cilia start to grow from the recently formed
blepharoplast granules in Equisetum (SHARP 8). Moreover, in the
Flagellata, which should furnish evidence more valuable than that
in the higher animals, it is known that in certain cases blepharo-
plasts arise from functional centrosomes by division (see MIN-
CHIN 7, pp. 82 ff.).

Although there is thus seen to be considerable evidence for the
derivation of blepharoplast fragmentation from normal centrosome
division, this evidence is probably best regarded as scarcely suffi-
cient to warrant the establishment of such an interpretation as
a general theory.

The question of the relation of the centrosome to the blepharo-
plast has been fully discussed by the writer in his papers on
Equisetum and Marsilia (8, 9). It will be sufficient here to recall
that the conclusions were reached that the blepharoplasts of bryo-
phytes, pteridophytes, and gymnosperms are “‘ontogenetically or
phylogenetically centrosomes” (IkENO); that these centrosomes

ecome more and more restricted in the life history in passing
upward through these groups; that they are retained in sper-
matogenous cells because of the biological importance of the
cilia-bearing function which they there perform; and that in con-
nection with this function they have become profoundly modified,
losing many of the characteristics of centrosomes and assuming
new characteristics not exhibited by centrosomes elsewhere.

To these conclusions Blasia furnishes support of no new kind;
it merely confirms them by affording another example of blepharo-
plasts arising from centrosomes functional in mitosis. How exten-
Sive this centrosome behavior is in the case of Blasia the present
study may not show, for, as stated in the description, the writer’s
material does not enable him to say whether the bodies in ques-
tion arise from preexisting ones by division or not, or whether they

266 BOTANICAL GAZETTE [MARCH

are present at only one or more than one spermatogenous mitosis.

So far as actual evidence goes, it is possible to state unreservedly

only that they are present from the stage represented in fig. 1
onward, and that through the single mitosis they appear to per-
form the usual functions of centrosomes. The discovery of frag-
mentation in the blepharoplast of a bryophyte serves to confirm
the view that the blepharoplasts of alt groups above the algae are
homologous structures, and the details of the process aid mate-
rially in accounting for the behavior of those blepharoplasts which
have become least centrosome-like.

Summary

1. Centrosomes are present in Blasia at all stages of the mito-
-sis which differentiates the androcytes, and in the androcytes they
persist and function as the blepharoplasts.

2. In the transformation of the androcyte into the spermato-
zoid, the blepharoplast fragments repeatedly by simple fission,
forming a number of distinct granules which coalesce to form a
short lumpy rod. This rod elongates and becomes a more uniform
thread bearing two cilia, while the nucleus also elongates in inti-
mate union with it to form the body of the spermatozoid. The
present instance is the first in which blepharoplast fragmentation
has been reported in a bryophyte.

3. It is possible that the fission of the Blasia blepharoplast, and
therefore the more complex fragmentation of the blepharoplasts
of Equisetum, Marsilia, and the cycads, may be homologized wit
the norma] division exhibited by ordinary centrosomes.

CORNELL UNIVERSITY

LITERATURE CITED

1. ALLEN, C. E., Cell structure, growth, and division in the antheridia of
Polytrichum junibesinuis Willd. Archiv Zellforschung 8:121-188. pls.
6-9. 1912

. The spermatogenesis of Polytrichum juniperinum. Ann. Botany
Ce 165403. pls. 15, 16. 1917.

3- Brack, CaRouine A., The morphology of Riccia Frostii Aust. Ann.
Botany 27: 511-532. pls. 97, 38. 10%3.

2.

.

1920] SHARP—SPERM ATOGENESIS 267

4. CHAMBERLAIN, C. J., Spermatogenesis in Dioon edule. Bot. Gaz. 47:
215-236. pls. 16-18. 1909.

HENNEGUY, L. F., Sur les rapports des cils vibratiles avec les centrosomes.
Arch. d’Anat. Micr. 1:481-496. figs. 5. 1808.

IkENO, S., Die eee von Marchantia polymorpha. Beih.
Bot. Genteitbl: 15:65-88. pl. 3

eee! E. A. An Bo . the study of the Protozoa. London.

a ow

Sih

; a L. W., Spermatogenesis in Equisetum. Bot. Gaz. 54: 89-110.
pls. 7, 8. 1912.
, Spermatogenesis in Marsilia. Bor. Gaz. §8:419-431. ls. 33, 34.

i]

*

IgI4.

- Witson, M., Spermatogenesis in the Bryophyta. Ann. Botany 25:415-
457. pls. 37, 38. figs. 3. 1911.

- WoopsurNn, W. L., Spermatogenesis in certain Hepaticae. Ann. Botany
25:200-313. pl. 25. IQII.

2. —_——, Spermatogenesis in Blasia pusilla. Ann. Botany 27:93-101.

cal
o

-
Lan]

4

, Spermatogenesis in Mnium affine var. ciliaris (Grev.)C.M. Ann.
Botany 29:441-456. pl. 21. 1915.

Le]
ios)
.

EXPLANATION OF PLATE XV
All figures were drawn at the level of the table with the aid of an Abbé

of the cells was made under a Zeiss 2 mm. apochromatic objective, N.A. 1.40,
but because of its slightly greater magnifying power a Spencer 2 mm. achro-
matic objective was used with an 18 ocular for outlining the drawings. The
figures, which have not been reduced in reproduction, show a magnification
of 4200 diameters.
Fic. 1.—Androcyte mother cell (penultimate spermatogenous cell) with
two Saree
Fic Widisare of last spermatogenous mitosis; centrosomes at poles
of decent spin
G. 3. = Metaphece. centrosomes at spindle poles.
Fic. 4—Late anaphase; centrosomes present.
Fic. 5.—Telophase; centrosomes near daughter nuclei.
vhs 6. ore telophase; each cell has one centrosome (blephoraplast).
—Androcytes (spermatids) rounded off; blepharoplast slightly
loncasa 5 in each; pa body near nucleus
IG. 8.—Pair of androcytes with pariah | in cytoplasm
Fic. 9 —Androcyte with dark body (limosphere ?) in patictens to blepharo-
plast.

a

268 BOTANICAL GAZETTE [MARCH

Fic. 10.—Pair of androcytes: blepharoplast undergoing fission in upper
cell; two Ce ae granules resulted from fission in lower cell.

Fic. 11.—Pair of androcytes showing elongation of one blepharoplast
granule.
Fic. 12.—Androcyte; slightly later stage.

Fic. 13.—Blepharoplast granules multiplying.

Fic. 14.—Later stage; granules somewhat coalesced.

Fic. 15.—Nucleus moving against blepharoplast.

Fic. 16.—Nucleus elongating by side of blepharoplast; blepharoplast
granules becoming coalesced.

Fic. 17.—Later stage; blepharoplast and nucleus becoming closely asso-
ciated.

Fic. 18.—Cell like that of fig.17 viewed from direction indicated by
arrow; blepharoplast lying along edge of flattened point of nucleus.

Fic. 19.—Later stage; blepharoplast still irregular in outline; boundary
_ between nucleus and blepharoplast indistinguishable.

Fic. 20.—Mature spermatozoid ready to escape from antheridium.

PLATE XV

BOTANICAL GAZETTE, LXIX

SHARP on BLASIA

CURRENT LITERATURE

NOTES FOR STUDENTS

Weather and fruitfulness——DorsEy' has done much to place on an
experimental basis a subject concerning which there have been many errone-
ous popular beliefs. In so far as it affects pollination and fertilization, he
divides weather into 4 components, rain, temperature, wind, and sunshine.

time. Contrary to popular belief, rain does not cause the pollen to burst,
and although the stigmatic fluid may be diluted thereby, this does not seem
to be injurious. Some pollen may be washed from the stigma by rain, but an
abundance is left for fertilization. Rain does not injure the viability of pollen.
Low temperatures retard the growth of the pollen tube, but do not seem to
cause delay in the abscission of the style. The stigma is receptive for 4-6 days
and then rapidly disintegrates. The style’ abscisses 8-12 days after bloom.

peratures, may therefore eliminate fertilization by preventing the pollen tube
from passing the point of abscission before the abscission of the style. Apply-
ing this analysis of weather to certain years of fruitfulness and to certain other
years of non-fruitfulness, it is found that each year there is a definite
correlation between the weather and the setting of fruit. The experiments
are thus given a practical test.—S. V. Eaton

Determination of biological fluids——Duggar and Dodge,? after dis-
cussing some of the difficulties encountered in examining biological fluids,
particularly colored plant juices, by the indicator method of H ion determina-
tion, describe a new method which they have found satisfactory for the exami-
nation of colored plant juices. ‘“The method consisted in simply arranging for
each side of the colorimeter a pair of cups slipping to a certain depth one into
the other. The method of procedure is then as follows. For the lefthand

* Dorsey, M. J., Relation of ene to fruitfulness in the plum. Jour. Agric.
Res. 17:103-126. pls. 13-15. fig. I
? Duccar, B. M., and Dopce, He ae The use of the asa in the indicator
method of H ion ictcshiatie with biological fluids. Ann. Mo. Bot. Gard. 6:61-70.
19IQ.

269

270 BOTANICAL GAZETTE [MARCH

set, or column, water (or colored standard solution) is used in the outer cup,
and the colored test fluid plus the indicator in the inner cup. After adjust-
ment, this set is not removed from the colorimeter during an observation. In
the case of the righthand set the outer cup contains the colored test fluid,
while the inner cup is for the standard solution plus indicator. This set
is placed on the right for convenience, as it may be necessary to compare
with the test fluid a series of standards until an exact match is obtained. A
rough comparison, of course, is made before selecting the standard solution for
comparison. In each case the column must contain an equal depth of colored
test solution and of standard or colorless liquid, the indicator being in the
standard in the one case and in the test solution in the other.. There are no
optical difficulties, and unless the indicator combines with the test solution,
the comparison may be perfect.” -
The authors believe this method is as rapid as and more accurate than
other methods.—J. Wooparp

Storied structure of dicotyledonous woods.—A recent paper by Record
continues his studies upon the storied or tierlike structure of woods. nds
this arrangement of the secondary elements characteristic of many dicoty-
ledonous woods, occurring through a wide range of orders and families. Such
woods on longitudinal section (particularly the tangential) present fine cross
lines or striations (“ripple marks”), which may be due to (1) the horizontal
seriation of the medullary rays, (2) the tierlike arrangement of the tracheids,
wood fibers, vessel segments, and the secondary phloem elements, or (3) 2
combination of (1) and (2). In some woods the pit areas on the fibers are also
in seriation. This storied structure has been found fairly characteristic of
the families Leguminosae (40 genera), Bignoniaceae (3), Bombacaceae (3),
Compositae (3), Malvaceae (4), ae (7), Tiliaceae (5), and Zygophyl-
laceae (3); and occurs in one or two genera of each of the following families:
Amarantaceae, Ebenaceae, Hippocastanaceae, Moraceae, Sapindaceae, and
Ulmaceae.

Particular attention oe been given in the present investigation to the
various elements storied, the uniformity and distinctness of these transverse
lines (ripple marks), and the height of the tiers in each wood examined.
“Ripple marks” are sufficiently constant in stems of considerable thickness to
serve, the author believes, as a “valuable diagnostic feature.” —-LADEMA M
LANGDON.

Antarctic and sub-antarctic vegetation—TuRRILL! has embodied in 4
convenient and useful summary the botanical results of the Swedish expedi-

3 RecorD, S. J., Storied or haere structures of certain dicotyledonous woods.
Bull. Tore on Club 46: 253-27
4 T URRILL, W. B., ccc poe of Swedish South American and antarctic
itions. Roy. Bot. Gard. Kew Bull. 268-279. 1919

1920] CURRENT LITERATURE 271

tions to the antarctic regions. These have appeared from time to time in the
report of SKOTTSBERG and others, and many have been noted in this journal.s
The more recent reports have contributed to our knowledge of the vegetation
of the portion of South America and adjacent islands between 48° and 56° S.
pes is a bce) heir covering a limited area, and composed of trees of low

eeding 10m. in height. The conspicuous species include
¥ pies Beiutoides, Drimys Winteri, Pseudopanax laetevirens, and Libocedrus
tetragona, the only conifer reaching Fuegia. In unforested areas dwarf shrubs,
many from the heath family, and cushion plants are conspicuous.

Farther to the north the Valdivian rain forest occupies the region between
the coast and the Andes, forming in the lower passes of the mountains a transi-
tion to the deciduous forest of the east slope. Between 41° and 44° S. a forest of
Libocedrus chilensis is interposed between the rain forest and the deciduous.
Many other formations are characterized, such as the pampas area east of
the Andes, the alpine heaths and meadows, the tussock grass and the tundras.
The bibliography includes 23 articles—Gro. D. FULLER.

Influence of environment on form and structure.—FoLsAm’ reports a
study of the effects of 5 different degrees of soil water supply upon the struc-
tural features of Ranunculus sceleratus and R. abortivus. Plants were grown as
pot cultures in a greenhouse. Water was supplied in amounts varying from
complete submergence of soil and plant, to only enough soil moisture to sup-
port life. In the 24 which were studied 6 structural characteristics of R.
sceleratus gave consistently larger values with progressively greater water
supply in the first generation of plants. In the second generation, 2 of the
6 characters continued to show the same relation. They were (1) thickness of
stem cortex, and (2) thickness of stem aerenchyma, both absolute and relative
to cortex thickness. In the first generation 5 structural features of R. abor-
tivus were found to be related in the same way to water supply. Of these the
one relation of increased laminar area of root leaves with increased water
supply was shown, although less consistently in the case of R. sceleraitus. A
third generation of the latter species was grown to determine whether the
conditions of water supply of parent affected the laminar area of root leaves
of progeny grown both as xerophytes and as amphibians. Seeds for this
generation were obtained from the xerophyte group of the first generation,
and from the amphibious group of the second generation. Progeny grown
with a large water supply gave consistently increased laminar area of root
leaves over plants grown with a small water supply, regardless of water rela-
tions of parents.—J. M. ARTHUR.

5Bor. Gaz. 58:96-98, 190. 1914; 631423. 1917.
6 Forsam, Donatp, The influence of certain environmental conditions, —
water supply, upon form and structure in Ranunculus. Physiol. Res. 2: 209-27
1918,

272 BOTANICAL GAZETTE [MARCH

Osmotic pressure in the potato.—In an effort to throw some light on the
physiological basis of tip-burn, LurmMAn’ has studied the osmotic pressure of
the potato plant throughout a growing season. In the young plant, when the
foliage is being formed, the osmotic pressure of the leaves is greater than that
of the stems. After the flower buds are formed and the tubers begin to grow,
the stalks predominate over the leaves in osmotic pressure. Sugars account
for the high pressures of the stalks. Tip-burn begins to appear at this stage,
This higher osmotic pressure of the stalks is maintained during the hot weather
of July and August. With the coming of cool rainy weather in September
and the resumption of growth of the foliage, the leaves again gain the ascend-

ancy. As the plant dies the osmotic pressure decreases, the soluble materials
being largely transported to the tubers. The osmotic pressure of the growing
tubers is always lower than that of the stems and leaves, although sie that
of the roots. The study does not explain tip-burn, although the author sees
two possible explanations of it: -(1) the loss of water from the leaves to the
stems, due to the higher osmotic pressure of the latter; and (2) the lack of
nourishment of the leaves, due to the translocation of food materials from the
leaves to the tubers. The author draws some other theoretical and practical
conclusions from his data.—S. V. Eaton

Anatomy of prairie plants.—Selecting the dominant species from some
prairie associations, Miss Haypen* has studied their leaf structure and pre-
sented considerable data, the most valuable being in the form of plates from
drawings of cross-sections. She concludes that prairie plants show a xerophytic
tendency in their leaf structure in the form of specialized palisade tissue, thick-
walled epidermis, the presence of water-storing tissue, and sometimes of
trichomes. ‘

In studying the subterranean parts of plants from the same habitats,
including a larger number from swampy areas, the same author? again presents
many data in the form of drawings. Her principal conclusions are that in a
dry habitat there is a tendency to the production of prominent mechanical
tissue and reduction of parenchymatous tissue. In moist habitats, however,
parenchymatous tissue is well developed and aerenchyma wamp

plants. The subterranean stem is EE NER NTE in moist peer regions, and
is more efficient than roots in propagation —Gro. D. FULLER.

. F., Osmotic pressures in ae Sie: plant at various stages of
growth. Avex. Tae Bot. 6:181-202. figs. 2
AYDEN, Apa, The ecological foliar peas ge some Le of a prairie province
in central ioe oa Lies oe 6:69-85. se FO-7 seh
9 tsofa prairie province
in central lows, Amer. Jour. Bot. 6:87—-1035. fis: segs 1910.

VOLUME LXIx NUMBER 4

5 TLE
BOTANICAL “(GAZE Tre
osacns os 1920

RIPENING OF PEARS AND APPLES AS MODIFIED BY
EXTREME TEMPERATURES
E. L. OVERHOLSER AND R. H. TAYLor

This work was undertaken as the result of an article by SHAMEL
(8), in which he stated that a box of hard ripe Bartlett pears were
placed in a lemon storage room where the temperature ranged
from 79 to 100° F., with an average of 83.5°, the relative hu-
midity varying from 85 to 96 per cent, with an average relative
humidity of 85.1 per cent. The pears were subjected to these
conditions from August 4 to September 3, 1916. Even though
surrounded by these comparatively high temperatures, the pears
remained hard and green until the end of the experiment (a period
of 30 days). Within 6 or 7 days after being removed the pears
ripened normally and were excellent to eat. As a check, SHAMEL
compared these pears with other lots which had been stored in a
room of a dwelling, where no attempt was made to control the
temperature or relative humidity, but where one would assume
both these factors would be lower than in the lemon house. Pears
from this family storage room were ripe within a week, by
August to.

SHAMEL states that the “condition of high relative humidity
was a controlling factor in retarding the ripening of the pears.”
He further states that ‘it is almost unbelievable that pears can
be held for 30 days at the high temperatures recorded, without
ripening or deteriorating.” . SHAMEL’s observations seem startling
when considered wholly from the viewpoint of experience in the

273

274 BOTANICAL GAZETTE : [APRIL

employment of cold storage and the utilization of low temperatures
for the purpose of delaying the ripening of fruit. On the other
hand, they seem to be in accord with certain observations which
indicate that high temperatures, as well as low, may tend to retard
the ripening process of fruit. In this connection the following
observations of the writers are of interest.

When certain varieties of plums and cherries, early in their
development upon the trees, are inclosed in closely woven, black
sateen cloth sacks, there is a delay of 4 or 5 days in the attainment
of maturity, and a prolonging of the period of edibility from 5 to
8 weeks after the crop of exposed fruits is normally harvested and
eaten (7). At the time these data were presented, it was believed
that light exclusion was the responsible factor; but in view of
SHAMEL’s observations, it might have been high temperatures and
high relative humidity in the area surrounding the fruits as a
result of the covering of black sacks, the black cloth absorbing

the heat rays and lessening the loss of moisture from the fruit.
At least it is possible that the activity of the enzymes bringing
about ripening was checked or partially inhibited.

BIoLETTrI (3) has noted that European varieties of Vitis vinifera L.
do not ripen in parts of California precisely according to the theory
of Ancor (z), who states that the buds of the European grapevine
commence activity when the mean daily temperature reaches
9° C. From this point until the ripening of the grapes, the sum
of the mean daily temperatures above 9° C. must reach 1130° C.
for the earliest varieties, and 1520° C. for the latest. BIOLETT!
finds that under Californian conditions the actual dates of ripen-
ing are from 2 to 4 weeks later than the time estimated by ANGOT,
and that the greater delays in ripening are in the hotter localities.
For example,in the Coachella Valley the seasonal sum of temperature
above 9° C. from February to November is 5728° F. Accordingly,
the grapes should ripen there from May 3 to May 23. Asa matter
of fact, the earliest varieties ripen about May 15-30, and the
latest about June 15-30. Burorerri thinks that in these hottest
regions the temperature of maximum acceleration may be passed,
and intimates that the temperatures may become so high that a
- retarding effect upon the ripening is exerted.

1920] OVERHOLSER & TAYLOR—TEM PERATURES 275

Pears in the Vaca Valley, near Vacaville, California, have
behaved in a way to indicate that high temperature may retard
ripening. Although the Vaca Valley is famous for its early fruits,
especially cherries and apricots, it is a well established fact that
Bartlett pears grown there are notably longer in reaching maturity
than those from any other section of northern California, unless
it be from the mountain sections where the seasons are very late
in opening, owing to their high elevation. One of the writers*
has often seen a full crop of immature Bartlett pears still hanging
on the trees in this valley when practically the entire crop was
gone from orchards in both coast and interior valley sections.
In the spring the pear trees blossom comparatively early, as do
the other fruits. The young pears develop normally until the hot
summer weather predominates, when they apparently almost
cease growth, or at least grow slowly until cooler fall weather
comes. Then the pears seem to commence growth again, often
increasing noticeably in size and ripening in the normal way. It
should be noted, however, that while the summer temperatures in
Vaca Valley are generally unusually high, the relative humidity
is practically always comparatively low.

In discussing SHAMEL’s interesting results and the results
obtained by the writers, later recorded in this paper, WHITTEN, of
the Division of Pomology, University of California, recalls observa-
tions which apparently bear upon this subject. He comments as
ollows

uring the summer of 1gor there prevailed in the Mississippi valley the
most severe drought and the highest temperatures recorded for that section
since the United States Weather Bureau was established. During that
s€ason pears remained firm on the trees much later than in normal years. In
numerous instances varieties were exhibited at fall and winter fruit shows in
Missouri, weeks later than the same varieties ordinarily keep for exhibition.
Similar retardation, but to a less degree, of the development of pears, in the
Same section, has been observed to occur during occasional subsequent dry,
hot summers.
The casual explanation, usually offered at that time, was that the develop-
ment of the pears was retarded by unfavorable conditions for growth, and that

? Observations made in Vaca Valley during the growing seasons since 1912 by
TAYLor.

276 BOTANICAL GAZETTE [APRIL

this retarded development resulted in later ripening. The results of investiga-
tions initiated by SHAMEL seem to justify the further interpretation that
tardy ripening during unusually hot summers may have been due to the high
temperatures opposing the ripening process.

that the higher temperature within the sack may account, in part at least, for
both later ripening and longer keeping qualities.

CARDINAL TEMPERATURES.—As is well known, certain cardinal
or fundamental temperatures are recognized. “Maximum” and

TABLE I
Minimum OprimuM MAxIMUM
PLANT
Cardinal temperatures for growth, ° C.
Com ieee 4.8-10.5 37-44 44-50
Chi ee ee 0.0- 4.8 25-31 31-37
Cucumber. 6's) 15.6-18.5 31-37 44-50
Wheat. ...2 0655s. 0.0- 4.8 25-31 ch as Fe
Barey... 2.2 0.0- 4.8 25-31 < 337
Cardinal temperatures for germination, ° C.

CAE re oy a 9.4 34.0 46.2

Maral a Er Ie 9.4 34.0 46.2

Corumbet 0 aks 14.0 34-0 46.2

ip EE alee 5.0 29.0 42.0

DRO oe ion 5.0 29.0 37-5

“minimum”’ are terms used to refer to the highest and lowest
temperatures at which the development of a particular organism
may occur. The most favorable temperature for any process OF
function is designated the “optimum.” The optimum tempera-
tures as a rule do not have a wide range. A variation of 5 oF 6°
one way or the other may be sufficient to have an appreciable
effect upon the process or function involved. Furthermore, it is
known that there may be separate maxima and minima for every
process or activity or tissue of the plant. As shown in table I,
HABERLANDT (6) gives a comparison of the relation of the different
activities of a few plants to these cardinal temperatures. These
figures are only suggestive, because the particular variety of the

1920] OVERHOLSER & TAYLOR—TEMPERATURES 297

same species and the other environmental factors would affect the
cardinal temperatures.

It would not necessarily follow that the best temperature for
the greatest vegetative growth of pears, for example, would like-
wise be the most favorable for fruit development, and this is
generally recognized by growers. Furthermore, the most favorable
temperature for the growth of the fruit on the tree may not be
the optimum for continued ripening of the fruit after harvesting,
with best flavor and resulting texture.

INHIBITION AT HIGH TEMPERATURES.—The fact is well known
that metabolism, enzyme action, and other processes or functions
of the plant are to a certain point rapidly increased with a rise
in temperature. BLACKMAN (4), however, has shown that the
maximum activity, especially for respiration and photosynthesis,
has commonly been placed too high, since proper consideration of
the time factor has not always been given. Above a certain
point it has also been clearly shown that high temperatures weaken
and lessen. general metabolic activities.

From work done by BALts (2) it is possible that the inhibition
of growth at high temperatures during a considerable period of
time may be the result of an accumulation in the cells of injurious
metabolic products. Batts thinks that some of these deleterious
products are produced at low temperatures, but under such con-
ditions they are decomposed about as rapidly as formed. At high
temperatures, however, production is more rapid than decomposi-
tion, and accumulation takes place which results in the injury or
inhibition of metabolism.

GorE (5), using temperatures from 2° to 35.6° C., found the
Tate of respiration increased an average of 2.376 seit for each
10° C. rise in temperature for 49 sets of determinations, with 40
different kinds of fruits. An interesting statement by Gore is
that “with many fruits the activity has been found to decline
when held at high temperatures.”

Experiment 1

In view of SHAMEL’s report and the degree to which it seemed
to be substantiated by minor similar experiments and observations

278 BOTANICAL GAZETTE [APRIL

of the writers, it was decided to conduct the following preliminary
‘experiments. While SHamet believed it was the high relative
humidity which was the controlling factor in retarding the ripening
of the pears, nevertheless the factor of high temperatures was
also present. Hence an experiment was outlined to endeavor to
determine whether high ees or humidity, or both were
ee

METHOD

To obtain for the test what appeared to be the more important
combinations of temperature and humidity, compartments were
arranged as follows: (1) To maintain high temperature and high
humidity a large drying oven, having a ventilation outlet at the
top, was arranged with four shelves above two electric heaters.
Between the heaters and the shelves were buckets of water with
sacks and towels hanging into them to increase the evaporating
surface. (2) For high temperature and low humidity a Freas
electtic oven was used with sufficient ventilation to maintain a
comparatively low relative humidity, but sufficient heat to maintain
a comparatively high temperature. (3) Two lockers were main-
tained at room temperature, one with ordinary humidity of the
room and the other with provision for maintaining a high relative
humidity. (4) The cold storage room where a check lot of pears
was kept, was maintained constant by means of a thermostat, so
that the temperature was always between 30.5° F. and 32.8° F.,
with the relative humidity ranging from 67 and 73 per cent.
Throughout the experiment, which continued for 21 days, one
hygrothermograph was kept on the third shelf (next to the bottom
shelf) in the large drying oven, and another in the locker with
normal temperature and high humidity. These were both checked
several times by wet and dry bulb psychrometer and tested mer-
curial thermometers.

Eight 5 Ib. grape baskets were filled with Bartlett pears and
placed at noon on September 2 in the various situations. Each
lot was numbered and described as follows:

Lot 1, top shelf (no. 1) of large oven; high temperature 85° F. and high

umidity too per cent.

1920] OVERHOLSER & TAYLOR—TEMPERATURES 279

Lot 2, next to top shelf (no. 2) of = oven; high temperature 88° F.
and high humidity 100 per cen
Lot 3, next to ear shelf (no. “ a large oven; high temperature
° F. and high humidity 91 per cent.
Lot 4, bottom shelf (no. 4) of large oven; high temperature 104° F. and
moderate humidity about 60 per cent.
Lot 5, in cree Freas electric oven; high temperature 95° F. and low
ity well below 50 per cent.
Lot 6, BE a locker in concrete building; room temperature 71° F.
and room humidity about 60 per cent.
Lot : lhe locker in concrete building; room temperature 69° F
and high humidity 92 per cent.
Lot 8, held i in cold storage at between 30.5° and 32.8° F. and a humidity
ranging from 67 to 73 per cent.

OBSERVATIONS ON TEMPERATURE AND HUMIDITY

In addition to the continous hygrothermograph records made
by lots 3 and 7, the writers made careful check readings on ther-
mometers at intervals of 1 to 4 days apart. For reference, these
are given in table II.

TABLE II
: ‘TEMPERATURE RECORDS DURING STORAGE TESTS
Temperature of lots in ° F.
Date Time
I 2 4 4 5 6 7 8t
September 2...| 11:10 A.M. Bee Fa 8 F801 F006 don ibs camer te nan 3
3:00 P.M. 84.0 | 89.0] 92.0] 104.0] 86.0] 70.7 | 70.0] 31.0
6 9:45AM. | 83.2 | 89.0| 95.2] 107.6.| 87.0 | 69.2 | 68.0 | 32.8
7 Q:G0 Am. | 64°65 | 00-6 | 206.71 107.01. ces 68.5 | 31.4
I2:15 P.M. | 88 90.0 £5.08.9 4 S12:8.1.5. 6.05 69.2 | 67.5 | 30.5
10 3:45 P.M. 5 | 90.0] 95.7 | 107.6 | 96.8] 70.0 | 68.0 | 32.7
I4...| 12:00 Noon | 84:0 | 87.0 | 92.2 | 100.8) 97.7 | 72.7 | 79-2 | 32-4
16 EATS PMS ps a: 85.5 | 93.0 | 102.2] 96.8 | 71.0] 69.0 7
19. 45 Paes het 86.0 | 93.2 | 103.1 | 93.6] 72.0 | 69.5 | 32.4
TRAC AMG Oe ee hie 84.0 EP DALE Wie sere 2.8
20 SAR EM a ek 97.01 9710 |. BPS Ge, meet!
2I ELAS AM Petite A 97:01) 90:25) SORE tevies.} snus 30.8
23 GtAt AM lca 300.5 | 107.9 | 1OS.0 foi. pecs ces 30.7
leibecien cet CRE ane a $4.0} 87.7 105.0 | 203-71 9 0.7 at.7
Maximum,|............ 88.5 .o | 100.5 | 112.1 | 103.1 | 72.7 | 70.2 | 32.8
Minimum.|............ 83.2 | 85.5 | 77-0] 77.0 2 30.5
* Electric current off from rr: 45 A.M. to §:40 P.M. only.

the mf Temperature with lot 8 in cold storage remained quite uniform, rising to the maximum and dropping to
the minimum with each run of the compressor about every 3 hours.

280 BOTANICAL GAZETTE [APRIL

The records were made immediately on first opening the doors
to the ovens or other compartments, two observers working to-
gether. During the time observations were being made, the
temperatures as well as the humidity dropped, but the hygrother-
mograph charts show that under the high temperatures prevailing
in the large oven, normal conditions were restored in 30 minutes
to 2 hours as regards temperature, and in 1 to 2 hours as regards
humidity. In the locker with lot 7, with air temperature normal,

TABLE III
Humipiry RECORDS DURING STORAGE TESTS
Pp tage of relative humidity of lots
Date Time

; I 2 3 7 8*
September 2...| 11:10 A.M 100 100 O0.0 ih odas 69.0
3..-| 3:00PM 100 6 Ei as 82.0 68.0
6. 9:45 AM 100 100 89.0 84.0 73-0
7. 9:00 A.M 100 100 88.0 92.0 69.0
Q..:] 12:35 Pu 100 100 82.5 96.0 67.0
Io. 3:45 P.M 100 roo 83.0 Q1.0 73-9
14...| 12:00 Noon 100 100 94.0 96.0 69.0
BOs | OCIS PM Picco es 100 93-0 98.0 79.0
16... L545 PM ot 100 89.0 97.0 72.0
20. DEAR AM ae POO acute 73.9
at. Uae BM oe ea ae OBS Oh sai eed 68.0
23 Wee tse Of0 Ge 68.0
shakin gt kad GEAR oe 100 100 90.7 gl. 79.0
wc aie ces CeCe Ee 100 100 100.0 98.0 73-9
ee Se ae di ee 100 100 82.5 82. 67.0

(oh oi
* Humidity with lot 8 in cold storag ined quite uniform, rising to the maximum and dropping
to the minimum with each run of the compressor about every 3 hours.

high humidity was restored in 4 to 10 hours after closing the door.
In no case, however, did the humidity drop below go per cent and
remain there for more than one hour. The slow rise from 95 to
roo per cent, or to saturation, required the longest time.

The observations on humidity are shown in table III. Lot 4
ranged about 60 per cent humidity; lot 5 ranged well below 5°
per cent; and lot 6 ranged from 53 to 65 per cent humidity. Lots
1 and 2 are indicated as having always been in a saturated at-
mosphere. This was assumed from the fact that every time the
door was opened to take readings, the walls, top, and bottom of

1920] OVERHOLSER & TAYLOR—TEMPERATURES 281

the shelves were covered with drops of precipitated moisture,
and the wrapping paper surrounding the fruits was always moist.
This was not generally true with lots 3 and 4. The condition of
the fruit itself, as indicated by its wilting, should serve as a good
indication of the relative humidity of the atmosphere surrounding
the various lots. This will appear later.

BEHAVIOR OF FRUIT

In the beginning of the. experiment all the pears were very
similar in degree of ripeness, all being yellowish green and about
one-fourth ripe, as indicated by color. Degree of ripeness may
be described from two standpoints, namely, appearance, indicated
largely by color, and condition, indicated by texture, juiciness,
and flavor. It was possible to describe the former as a certain
fraction ripe, and the fractions in table IV refer to ripeness in
appearance only, unless otherwise noted. Additional statements
cover condition. The pears in each lot were examined at approxi-
mately 4-day intervals, and careful notes made as to appearance
and condition. The somewhat abridged notes in table IV indicate
the condition of the fruit as the experiment progressed.

_ The experiment was continued beyond September 23, but on
the 25th an accident in the regulation caused the temperatures
to climb abnormally high in the box where nos. 1-4 were located.
The result was that the pears in lots 3 and 4 were cooked brown,
so that further observations were impossible. It was interesting
to note, however, that lot 3 was cooked much more severely than
lot 4. The temperature of lot 3 as compared with lot 4 was
approximately ro° lower, while the relative humidity was about
3° per cent higher. Just before this, one fruit each from lots 3
and 4 were placed where lot 7 had been at room temperature and
high humidity, to discover whether these fruits would ripen
normally after removal from the high temperature. These fruits
were observed and sampled on September 28. No. 3, although
noticeably wilted on September 23, had by the 28th become
apparently more plump, appearing almost normal. The fruit was
full soft ripe; flesh rather tough; and flavor more acid than normal,
with a faint trace of bitterness, although this may have been due

BOTANICAL GAZETTE

282

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OVERHOLSER & TAYLOR—TEMPERATURES 283

1920]

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284 BOTANICAL GAZETTE [APRIL

to the absorption of the odor from the cedar wood closets in which
the fruit was held. At any rate, the ripe fruit was much poorer
in quality than the Bartlett at its best when ripened at normal
temperatures. No. 4 was still as wilted as before. Fruit was
full ripe, but dry and tough. This fruit remained about as
wilted as when first placed. The fruit was not soft, but as
much so as it ever would be without being well past ripe. It was
very inferior in flavor and quality, much the same as no. 3.
Lot 8, which was held in cold storage throughout the progress
of the experiment, showed almost no appreciable ripening, being
practically as hard and unripe at the = of the month as at the
beginning.

DISCUSSION OF RESULTS

The pears in lot 1, placed at a temperature averaging about
85° F. and in a saturated humidity, were full ripe 8 days after being
subjected to the conditions. A study of table IV shows that the
pears in lot 2, placed at a temperature averaging 87.7°F. and in
a saturated atmosphere, were full ripe about 13 days after being
subjected to the conditions. Since the fruit was all in the same
stage of maturity before the experiment started, this would show
a delay of 5 days in ripening, which can only be accounted for by
the fact that the temperature was about 3° higher.

The pears in lots 6 and 7 were also full ripe 8 days after the
experiment started. The temperature surrounding lots 6 and 7
was practically the same in both cases, and averaged about 70° F.

e difference in the conditions surrounding these two lots was in
the humidity. The humidity in the compartment containing lot 6
was fairly constant, about 60 per cent; the humidity surrounding
lot 7 averaged about 92 per cent. The temperatures alike, the
difference in humidity showed no effect upon the ripening... Fur-
thermore, when compared with lot 1, the fruit ripened with ap-
proximately the same rapidity at temperatures of 70 and 85°F.
The pears in lot 3 remained firm unripe for 3 weeks after being
subjected to a temperature averaging about 94°F. and a humidity
of 91 per cent. This shows a delay of 13 days when compared
with lots 1, 6, and 7. This apparently was due to the somewhat

1920] ' OVERHOLSER & TAYLOR—TEMPERATURES 285

greater temperature at which the pears were kept. The some-
what lower humidity resulted in the pears wilting appreciably.
The pears in lot 4 were hard unripe, or not quite as ripe as the fruit
in lot 3. The temperature averaged about 104°F. and the humidity
approximately 60 per cent. The higher temperature resulted in
an appreciable delay in ripening when contrasted with lot 3,
but the lower relative humidity caused considerable wilting. With
the high temperatures some difficulty was experienced in maintain-
ing as high humidity as was desired in the case of lots 3 and 4.

INTERPRETATION OF RESULTS

It is somewhat difficult to account for the surprising results
obtained. The general idea has been that low temperatures only
were 6f importance in preserving fruits for any period of time and
in arresting the deteriorating processes. As contrasted with this,
high temperatures were looked upon as extremely conducive to a
hastening of the breakdown of the tissues and in shortening the
keeping period of fruit.

The delay in ripening might be assumed upon the Manis of an
accumulation of carbon dioxide, the assumption being that pos-
sibly a comparatively large mass of fruit stored in a relatiyely
small closed container, at high temperatures, would result in an
abnormal amount of carbon dioxide surrounding the fruit. The
writers, however, doubt whether there was any measurable ac-
cumulation of carbon dioxide, since the capacity of the drying oven
was relatively large for the amount of fruit contained therein.
Furthermore, the ventilation pipe at the top permitted the warm
air to be continually escaping. In addition, the oven was opened
about every 3 days to make observations and add water to the
evaporating pan. This would give a good aeration. The writers
at first felt that the explanation might be that with certain low
temperatures conditions result whereby not only katabolic activity
or destructive metabolism but all metabolism is lessened or reduced
to a minimum. On the other hand, with high temperatures and
high relative humidity surrounding the fruit, conditions may be
produced whereby the tissues are able, at least partially, to
catry on anabolic activity or constructive metabolism,.and hence

' 286 BOTANICAL GAZETTE {APRIL

indirectly lessen the amount of rapidity of activity which would
bring about deterioration.

As a result of further work, however, it seems shoe that
within a given limit high temperatures may act in the same manner
as do the low temperatures to which fruits. are subjected in cold
storage; that is, temperatures approaching certain limits in either
extreme cause a reduction in the protoplasmic and enzymatic
activities of the fruit,-and this, depending upon the extent of the
inhibition, delays to a greater or less degree the attainment of
ripeness. As has been stated elsewhere, the experiments reported
upon are of a very preliminary nature, and an effort is being made
to repeat them. Furthermore, at such high temperatures for any
long period of time the flavor might be affected so that the quality
would be appreciably lowered. As a matter of fact, the ‘flavor
of the pears subjected to the higher temperatures was somewhat
abnormal. A slight acidity was noticeable and a lack of the
normal sweetish taste and juiciness was apparent. This can
probably be accounted for by the fact that the comparatively
high temperatures would be expected to increase the respiration.
Carbohydrates are necessary for respiration, and are gradually
used by this process; hence it follows that the sugar content
would have been decreased. This decreasing of the sugar content
would have made the normal acid content somewhat more notice-
able, and, in addition, it is possible that intramolecular respiration
may have been carried on to a certain extent, and this give rise
to waste products that affect the flavor.

A second drawback to the practicality of utilizing high temper-
atures and high humidity in keeping fruits is the danger from rot.
Under such an environment, conditions are very favorable for the
growth of fungi or bacterial organisms which would bring about
the decay of the fruit. While the experiments, therefore, show
that temperatures ranging from gs to 110° F., with the optimum
at about 104 or 105° F., will delay or prolong the normal ripening
process of Bartlett peaks at least two weeks, when contrasted
with fruit placed at average room temperatures of 7o to 80° F.,
the danger from rot and the development of abnormal flavors
limit the practical use of these higher temperatures. ©

1920] OVERHOLSER & TAYLOR—TEMPERATURES 287

Experiment 2
In the preceding experiment with the highest temperature
used (104° F.) the Bartlett pears kept longest. The authors
wished to ascertain whether temperatures higher than those
employed in the first experiment would be more satisfactory.
To determine this, and also to repeat in a measure the first experi-
ment, a second experiment was conducted.

OBSERVATIONS ON TEMPERATURE AND HUMIDITY

The method of procedure was just as outlined for the first
experiment, except that the temperatures in the large drying
Oven were somewhat higher than was the case in experiment 1;
that is, the top shelf (no. 1) had a temperature averaging go° F.
as contrasted with 85°F. in the first experiment; shelf no. 2
averaged 99.2° F. instead of-88° F.; shelf no. 3 averaged 109° «’.
instead of 94° F.; and shelf no. 4 averaged 121.2° F. as compared
with 104° F. The Freas oven averaged about ror°F.; while in
the first experiment it was kept at about 95° F. The other temper-
atures and the humidity were just about the same as for the first
experiment.

The experiment was begun on September 25, 1918. One set
consisted of 5 lb. grape baskets filled with first crop Bartlett
pears; a second set consisted of second crop Bartletts; and the
third set was filled with Easter pears. One lot of each set was
placed under each of the varying conditions. By an improved
alrangement for maintaining a high humidity, it was possible to
fill the water pan from outside without opening the door of the
Oven. Since the writers knew just about what to expect from the
large oven as well as the other compartments, and since the hygro-
thermographs were operated throughout this experiment as in the
first one, it was not found necessary to open the door at frequent
intervals to take readings. The hygrothermograph showed that
the temperatures and humidity were quite uniform, in fact more
so than in the first experiment because of better control, except
On two occasions. The first was from noon, Septémber 28, to noon,
September 30. During this time the water pan was dry and the
humidity dropped eso! below 50 per cent. At the same

288 BOTANICAL GAZETTE [APRIL

time the temperature rose from 4 to 6° F. only above the tempera-
tures indicated, as shown by the continuous record of the thermo-
graph pen. The second was during the last 36 hours of the
experiment, ending October 10, when the pan again went dry. The
operation of the thermostat prevented any rise in temperature
above the normal. In fact the thermostat was so closely adjusted
that the variation in temperature at the hygrothermograph was only
from 1 to 2° F. at any time except when the door-was open.

The variation in humidity was somewhat greater on the bottom
or fourth shelf, although it was probably close to 90+ 5 per cent.
On the first three shelves the humidity was 1oo per cent throughout
the experiment, except during the times indicated. Room tem-
peratures and humidity were practically the same as in the first
experiment, not more than 1° F., or 6 per cent difference between —
the maxima and minima. The high humidity at room tempera-
ture was quite uniform, ranging from 94 to too per cent, average
96 per cent. The cold storage temperature and humidity were
just the same as in the first experiment.

BEHAVIOR OF FRUIT

The first crop Bartlett pears were near the end of their life
period when first subjected to the experimental conditions. As a
result, 3 or 4 days after the experiment was begun nearly all the
specimens were physiologically broken down, as indicated by the
blackening of the skin, and the browning and extreme softening
of the tissue. No data of value, therefore, concerning the effects
of high temperatures upon keeping quality, were obtained with
this lot of nearly ripe Bartlett pears.

The second crop Bartlett and the Easter pears were green
enough to show a response, with wide enough differences, depend-
ing upon the temperature, to be of interest in substantiating the
first experiment, and to determine the effects of temperatures
higher than those employed in the first test. The details of these
are given in tables V and VI.

As indicated by the nearly ripe Bartlett pears, there is a point
near the stage of complete maturity in ripening at which break-
down may rapidly come about, regardless of the environment.

1920]

OVERHOLSER & TAYLOR—TEMPERATURES

TABLE V

CONDITION OF SECOND CROP BARTLETT PEARS DURING PROGRESS OF SECOND TEST,
PTEMBER 25 TO OCTOBER 10, 1918

289

DATE OF EXAMINATION

Lor No. TREATMENT
September 28 October 3 October 10
for, High tem ai Only slightly si . “ts , unripe, | Firm, no prcny
(90° F.), hi riper than nish yel- nearly
midity ( ee or when started foe, extreme thee fourths
cent) aturatio ored,
developing i
mold on frui
ee High ME pees Only male a4 Firm, unripe, | Firm, no wilting,
(99.2° F.), high . rt supersatw nearly yellow,
aaa ity (6 when iated - not quite as
per cent de- as lot 1
veloping mold :
aie. High oe hiek pap flag aes Firm, unripe, | Firm, no wilting
(109° F.), h et | greenish yel- Soady. yellow,
humid dity ox Se when pista: low; 1 fruit not quite as
nt) slight brown- ripe as lot 2;
ing at stem 3 fruits sli
end, others breakdown at
small brown Meee
rotten spots in flavor,
quality very
poor
ORES High temperature | Slight browning | All chocolate | All gone
(2:92.9" Fo), of skin to one- colored
moderate hu third break- throughout,
midity ( per down cooked taste,
cent) ite firm
i... High Rodan Same as lot 3 Firm, unripe, | Firm, wilted, not
(z01° F.), lo greenish sn ripe, same as
midity walt es low, same lot 1*
low 50 per cent) lot 3
Mics Room temperature | About the same | Fullripe, almost | Soft ripe,
(73° F.), room hu- as lot 1 at best eating clear yellow, at
midity (60 per poeaition, or slightly past
cent) light yellow, best eating, no
slightl wilting
ilted
Peet y, Room Seg ears Same as lot 6 Same as lot 6 Same as lot 6
(69° F.), ages
a " (96 p
a ear aie (32° | Same as when | Same as when | Practically same
F.), moderate hu- | _ test started test started as when test
midity Oe per tarted
at)
*The second crop Bartlett pears of this lot was allowed to remain in the Freas oven until November 5
On this date, nearl started, the fruit could be described as fve-sixths
colored, unripe, 4 ithsoiy eager. ype preiatectong insipid, but not displeasing in flavor.

290

BOTANICAL GAZETTE

TABLE VI
ConDITION OF EASTER PEARS DURING THE PROGRESS OF THE SECOND TEST

[APRIL

- DATE oF EXAMINATION

Lot no. TREATMENT
September 28 October 3 October ro
1 ARES High temperature L Gr Teen, same as | Green, firm, un- rm, pe,
(90° F.), high hu- when first put ripe; half of lighter - green
midity ‘(100 per in, some mold fruits largely than when
cent) developing or er arg ti
Rhizopus and
Penicillium
mold
2200 High temperature Green, same as | Green, firm, un- irm, unripe,
{99.2 .), high when first put ripe; half of greenish
pasar (x °° in, some mold fruits large yellow; con-
= cent, or completely siderable mold
trotted with
hizopus and
Penicillium
mold
eam High temperature | Gree e as ie firm, un- | Completely
(109° F.), hea renee it nly roken down,
menage (1 per in, no mol slight sie at and rotted
ent) : of 2 mold,
tulle skin chocolate
brown, flesh
dirty white
col
4s ae re CE as Green, same as | Allfruitsseemed }........-.-++++>
(1 r 3, when first put ;_ ski
moderate hu- in, no mold chocolate
midity ' (70 colored with
cent) tissue soft and
grayish whi
with flecks of
brown scat-
ed
considerable
internal
breakdown
Se. gh temperature | Green, same as | Same as lot 3, | Unripe, light
“Ger F,) ow hae: when first put noticeably | green withfew
well be- | in, no mold wilted small patches
pig mi per cent) of yellowish
green, very

badly wilted

1920] OVERHOLSER & TAYLOR—TEMPERATURES 291
TABLE VI—Continued
DATE OF EXAMINATION
Lor no TREATMENT
September 28 October 3 October 10
Orcs Room gs ganent Green, same as | Green, firm, un- edi
(71° F.), room when first put ipe, ver ripe, yellowish
poaireoneed (60 per in, no mold slightly een,
nt) at best eating,
somew
y ees m temperature | Green, same as | Same as lot 6 Firm ripe, light
ma: F.), high hu- when first put but even a Aglaia
midity (06 in, no mold wilted, practi- green,
cent) cally plum as ripe as lot r
ee Cold storage (32° | Green, same as | Same as when | Same as when
F.), moderate hu- when first put put in put in
midity (7o per i
cent)

*

This is true notwithstanding the fact that earlier in the period of
ripening certain identical conditions, as contrasted with others,
would appreciably arrest the ripening process.

The results of experiment 2 indicate that for Bartlett pears
a nearly continuous temperature of 104-110°F., and a relative
humidity of 95-98 per cent, result in the most marked delay of
the ripening process when high temperatures are the factor em-
ployed. Temperatures above 110°F. result in a more rapid
breakdown of the tissue than do any temperatures below. A
temperature of 107° F. gives better results in delaying the ripening
than 110° F. When the moisture content of the surrounding air
is so high that water is precipitated on the fruit, the pears do not
keep nearly as well as when the relative humidity is just sufficiently
low to prevent this. This second experiment shows rather con-
clusively that within a certain limit high temperatures tend
appreciably to delay the ripening of Bartlett and Easter pears.
Excessively high humidity and these high temperatures, however,
make conditions favorable for the infection and growth of fungi
upon the pears. Low humidity and these high temperatures, of
course, result in excessive wilting of the fruit.

292 BOTANICAL GAZETTE [APRIL

Table V shows that the second crop Bartlett pears designated
as lot 5 were of especial interest, in that they remained unripe
for a relatively longer period than any of the other lots. Lot 5
was in the Freas oven at a temperature of 101° F. and surrounded
by a relative humidity below 50 per cent until November 5. On
this date, nearly 6 weeks after the beginning of the experiment,
the pears were still unripe. When compared with fruits stored
at room temperatures, this shows a delay in ripening of a little
over 4 weeks. This lot also is of interest in that it indicates that
it is a question of high temperature only, which causes the ripen-
ing processes to be inhibited, and that high relative humidity has
no marked influence, except to lessen the amount of wilting.

The question arises why the fruit of lot 5 should keep longer than
the fruit of lots 2 and 3, since the temperatures in each case were
all comparatively high. The chief difference between these lots
was the much lower relative humidity of lot 5, as contrasted with °
lots 2 and 3. It is probable that the greater desiccation or wilting
of the pears of lot 5 did retard their ripening, but two other points
should be mentioned. (1) When the relative humidity was high,
much trouble was experienced from molds infecting the fruit and
causing it to rot. There was no loss from rot in lot'5, due no
doubt to the very low humidity. (2) The temperature of lot 3
was no doubt too high, and it is probable that the temperature
surrounding lot 2 was somewhat below the optimum temperature
for the retardation of the ripening.

Specimens from lot 5 were tested by Dr. J. Rupiscu and the
senior author to determine if any enzymes were active. The
tissue was treated with a tincture of guiac and gave no test for
- oxidase, either with or without the addition of hydrogen peroxide;
neither could a test for an organic peroxide be shown upon the
addition of a solution of potassium iodide, weak acid, and starch
solution, as indicated by the liberation of free iodine and the
consequent blueing of the starch solution. This might indicate
that the higher temperatures had destroyed or inhibited the action
of the ferments or enzymes normally present in the tissue of pears.
This resulted in a checking of the ripening process with a con-
sequent prolonging of the period in which the fruit could be kept.

1920] ~ OVERHOLSER & TAYLOR—TEMPERATURES 203

Experiment 3
EFFECTS OF HIGH TEMPERATURES UPON KEEPING APPLES

Since Bartlett and Easter pears behaved in such an unexpected
manner when subjected to temperatures of around 104°F., an
endeavor was made to determine whether varieties of apples
would behave in a similar manner. Yellow Newtown apples,
which had previously been kept in cold storage at a temperature
of 32°F., were subjected to high temperatures similar to the
process in experiment 2.

The experiment was begun on December 12, with a 5 lb.
grape basket filled with apples subjected to each of the several
conditions. The temperatures varied as follows: 32, 70, 85, 95,
104, 110, and 120° F. The relative humidity was from go to
98 per cent in each case, except that the temperatures of 70°F.
and 104° F. were duplicated, the relative humidity in one instance
being somewhat below 50 per cent and in the other varying from
go to 98 per cent. The results of this experiment can be sum-
marized briefly. The ripening of the apples was not delayed by
the higher temperatures. The rapidity of ripening was directly
proportional to the temperature, in that with the degrees tried
the higher the temperature the more rapid the ripening. After
2 weeks the fruit subjected to temperatures of 85° F. and above
were all browned throughout and soft, tasting very much like
baked apples. The fruit at 70° F., or room temperature, was
yellow in color, ripe, and just about best for eating. The fruit at
32° F. was still green and hard unripe.

Practical applications

The practical applications of the data presented are somewhat
limited, but the facts may be of value some years and in certain
Sections in connection with the time of picking Bartlett pears.
For example, as a rule during the hottest seasons the growers have
felt a greater necessity for earlier picking than when the season
is normal at the time of ripening. In view of the results obtained,
it may really happen that the ripening of the pears is delayed by
the excessively hot weather, and would mean that the fruit might
well be allowed to remain on the trees longer than would be the

204 BOTANICAL GAZETTE [APRIL

case in a normal season. This would be of especial value when
fruit was being harvested and packed for eastern shipment. Pears
are picked comparatively early in order to reach distant markets
in good condition. While they should preferably not be allowed
to ripen on the tree, to avoid the marked development of the grit
cells, it might mean that in excessively hot years, contrary to
expectations, the fruit could be left somewhat longer on the trees,
and thereby develop a.better flavor and quality. If all varieties
of apples behave as do Yellow Newtown, high temperatures do
not delay ripening. Instead, up to the point of tissue destruction
by heat, the higher the temperature, the more rapid the ripening.
This emphasizes the necessity of hurrying into low temperatures
apples which are to be stored for any length of time.

Summary

1. When contrasted with temperatures between 70 and 85° F.,
temperatures of 87.7 to 110° F. caused an appreciable delay in
the ripening of green first crop Bartlett pears.

2. The retardation of ripening was directly proportional to
the increased degree of heat within the limits of 87 and 104° F.

3. The amount of delay in ripening of green first crop Bartlett
pears of the different temperatures when contrasted with 70° F.,
or room temperature, was as follows: 85° F., no retardatluns
87.7°, 5 days; 94° F. and 104° F., 13 days.

4. Second crop Bartlett pears, placed at a temperature of ror? F.
and surrounded by a relative humidity of below 50 per cent,
remained unripe 4 weeks after similar pears had, become fully ripe
at room temperature and humidity.

5. The relative humidity does not seem to be a significant
factor in checking the ripening processes.. Its effect is in lessening —
_ or permitting wilting, depending upon whether the relative igneh
surrounding the fruit is high or low.

6. The flavor of the pears subjected to those écinpematures
higher than 85° F. was not normal. There was a slight acidity,
and the sweetish taste and juiciness were lacking.

7. Temperatures above 110° F. result in a more rapid ripening
and consequent breakdown of the tissue than do any of the lower
temperatures, down to average room temperatures.

1920] - OVERHOLSER & TAYLOR—TEMPERATURES 295

8. As would be expected, there was a comparatively large
loss from rot with the fruit kept at high temperatures and sur-
rounded by high relative humidity. |

9. A possible explanation of the effects of high temperatures
may lie in the influence upon the enzymes. Temperatures
approaching the probable minimum (around 28° F.) on the one
hand, and the probable maximum (around 110° F.) on the other,
might result in a reduction of enzymatic activities of the fruit and
a consequent retardation of the ripening processes; while with the
optimum temperatures (70-85° F.) the enzymatic activity would
be most marked, and hence the ripening most rapid.

to. If the Bartlett pears have nearly reached a stage of complete
ripeness, the temperatures above 70° F. do not check the ripening
process. On the other hand, the ripening and breakdown are more
rapid with each appreciable rise in temperature.

11. Unripe Easter pears behave in a manner comparable to
the Bartlett when placed under similar conditions of high temper-
atures and relative humidity.

12. The process of ripening with Yellow Newtown apples is
not delayed by temperatures above 32° F. The ripening takes
place with increased rapidity with each appreciable rise in temper-
ature above 32° F. This is true with temperatures up to a point
which result in the disorganization of the protoplasmic contents
of the cells.

13. The experiments suggest that with an excessively hot
season during the time of ripening, Bartlett and Easter and
possibly other pears might be allowed to remain on the trees
somewhat longer than with a normal season.

14. For Yellow Newtown and no doubt other varieties of
apples, which are to be stored any length of time, the necessity of
quickly cooling after harvesting is malaga

UNIVERSITY OF CALIFORNIA

BERKELEY, CAL.
LITERATURE CITED

1. Ancor, A., Etudes sue les vendanges en France. Ann. Bureau Central
Meteorlogique. 1883.

2. Batts, W. L., Temperature sid growth. Ann. Botany 22:557-592. figs.
II. 1918.

*

2096 BOTANICAL GAZETTE [APRIL

3- Broretti, F. F., Viticulture on the Pacific Coast. Official Rep. Session
Internal Congr. Viticul. P.P.I.E. San Francisco, California, July 12-13,
IQI5. pp. 81-88.

4. ae F. F., Optima and limiting factors. Ann. Botany 19: 281-295.
figs. 2. 190

5 Gore, H: C., Studies on fruit respiration. Bull. 142., Bur. Chem. U.S.D.A.
IgIt.

(6. HABERLANDT, F., Die oberen und unteren Temperaturgrenzen e
Kennung der eichiieetiat Landw. Samereien Landw. Versuchsstation
1'72104-116. 1874

7. OVERHOLSER, E. oe Color development and maturity of a few fruits as
affected by light euchaions Proc. Amer. Soc. Hort. Sci. pp. 73-85. 1917-

| SaaS and storage of fruits. Bull. Calif. State Commission of Hort.
62 no. 2. 1917.

DIAPHRAGMS OF WATER PLANTS
Il. EFFECT OF CERTAIN FACTORS UPON DEVELOPMENT OF
AIR CHAMBERS AND DIAPHRAGMS
LAETITIA M. SNow
(WITH THREE FIGURES)

The experiments reported in this paper were started at Wellesley
College in 1914-1915, and were continued at the University of
Chicago during the winter of 1915-1916. It was intended to
repeat the experiments and confirm the results, but as it has been
impossible to do so, it seems better to report the work in its present
incomplete condition than to delay its publication any longer.
Thanks are due the Association of Collegiate Alumnae for the
grant of the Alice Freeman Palmer Memorial Fellowship for 1915-
1916, the Missouri Botanical Garden for the material of Scirpus
validus which was collected and started at St. Louis, and the
botanical staff of the University of Chicago for their cordial co-
operation in placing the facilities of the laboratory at my disposal.

Water
As the general impression is that an increase in the water con-
tent of the soil produces an increase in the amount of air-containing
tissue, culms of Scirpus validus were allowed to grow alternately
under water and in the air, in order to note the effect of the change
upon the air spaces and diaphragms.

EXPERIMENT I

In order to be sure that the part studied actually grew under
the desired condition, it was necessary to ascertain the region of
gtowth of the stem. Consequently in 1914-1915 culms were
marked in 2 mm. sections from the tip downward. In some cases
the marks extended to the sheathing scale leaves at the base
(called “‘to sheath”? i in table I); in others the sheath was stripped
oat and the marks carried down the stem to the rhizome (called

culm” in the table). DD 5 showed a discrepancy between the
297] [Botanical Gazette, vol. 69

298 BOTANICAL GAZETTE _ [APRIL

millimeters of growth and the distance of the last mark from the
ground, As it grew 33 mm. and the last mark was 38 mm. from
the ground, the difference of 5 mm. might mean that three marks
had disappeared. If the first was at the base, the stretching, in
destroying these marks, could not have extended farther than 5 mm.,
as the last mark visible was clear cut and 2 mm. from the one next
above it. The discrepancy was more likely to have been the
result of faulty measurements.

. TABLE I
REGION OF GROWTH IN Scirpus validus
Pot Culm no. Marking Region of growth
Becca ot I To sheath growth
Wey ia re ee as ORS 2 To sheath Boe top of sheath
Ge i at Geers: 3 To sheath (?) | Below top of sheath
Whe Tat cer ne ewb che 4 eath N

Bee het cies 3 To sheath (?) o growth
Se OOP Pere 4 eath Below top of sheath
Recs or ccts wend: 4 u | Below last mark
RR ea eres 5 Culm Below last mark :
SS ae 4 To sheath . Noon fon: of sheath
SX BE Soe hae Tee 2 To sheath
Oo a re 4 Culm Below ap t mark
bE | 3 ERTS mae 5 Culm Below last mark (?)

EXPERIMENT 2
In February 1915, 11 culms were marked, 6 to the top of the
sheath and 5 on the stem to the base. After a period of growth
all marks were clear cut, and showed no separation. This may
mean that all growth took place below the last mark, or that some
of the marks had disappeared. To test this, experiment 3 was
started.
EXPERIMENT 3
In March 1915, 4 culms were marked to the base, as just
described, and the number of marks counted. One culm did not
grow. In the second culm, after one day, the lowest mark had
disappeared; the second mark was 4mm. from the base and was
perfectly clear cut. The other marks had not changed. In the
third culm, after 7 days, the first mark was at the base on a piece
of sheath; the second was clear and 13 mm. above the base.
In the fourth culm, after 7 days, the first mark was on a piece

1920] SNOW—DIAPHRAGMS 299

of sheath; the second was clear and 4mm. from the base. The
third culm was marked again, and by the next day the first mark
had disappeared and the second mark was 4 mm. from the base.
From these experiments it seems reasonable to conclude that the
growth of Scirpus validus takes place within an extremely short
distance of the base, possibly as short as 2 or 3 mm.

' EXPERIMENT 4

While the foregoing experiments were in progress, others were
started, to test the effect of the medium upon the growing region.
Pieces of rhizome were potted, practically at the surface of the soil,
and placed under water. When the culms were well grown, the
water was allowed to evaporate until the surface of the soil was
exposed to the air. When the water level had fallen to about an

TABLE II
VARIATION IN GROWTH OF Scirpus validus WHEN CHANGED FROM ONE MEDIUM TO
ANOTHER

WATER TOAIR - AiR TO WATER
Por Accelerated Retarded Accelerated Retarded Unchanged
No. of | Mm No. of | Mm. No. of | Mm. per | No. of |Mm. per] No. of
ps Mh — a aor culms day culms

ee a I 16.0 I 22.0 I OS sie ees I
Bee SS EEE aia, oa Eh Pua a I a he Crue Agape ne patie raha
AGE Cane als seen I 5.0| 2 oe wee wide G Sak Gat

edie che eat eee I 11.0 I EO Hise. feuess: I
EOE Seen Gere rae. I 12.0 I is I hoe Pere
geet eee mei sR eae I CES BOs eae eS es

15.0 Ce Ree ore I
AALS. I 2.0 2 { o.8 |: 2 ae ee) EGS er Ae
1.0 I Oh Eee a
BBe eee pieces Fig Ce ae ee ee ee
er cay Pears, Saget C4 Rae
eine. ce JER ors) aes anes Wane
WE ls I 17.5 I Pe ie, Sansa) Papas Ene ee ae
nee BR, Serena SG er
We Oty A as hs 2 ee oe a
Averages .|...... $050. 1c ks 166 oh BA ceca ee ee

yest Me te Pees ee ee 1k Bo as 3

300 "BOTANICAL GAZETTE [APRIL

inch below the surface of the soil, it was maintained at this height
by regulating the amount of water in the surrounding vessel.
This allowed the culms to grow in the air, while the roots had
an abundant supply of water. All were grown under these con-
ditions for a certain period, which differed for the different pots,
after which they were again submerged. Careful measurements
of the growth were made throughout the experiment, and at its
close longitudinal sections were made in the regions which had
grown under the different conditions, and measurements made
of the distances between the diaphragms. The results are shown
in the tables.

EFFECT ON GROWTH.—From table II it might be concluded that
a change from water to air retards growth, and the reverse change
accelerates it. Two
facts, however, must be
noted: (1) in some cases
in the same pot one
culm was growing faster
after the change, while
another was growin
more slowly; and (2) the
temperature was not
controlled. Toward the
latter part of the experi-
ment an effort was made
to keep a record of the
variation in tempera-
ture. ‘A recording ther-

Culms accel. 9 = 150 is > ; mometer was not avail-
—— bo ~~ 4 1 able, consequently four

1 1

Fic. 1.—Effect of temperature and surrounding
medium upon growth of culms of Scirpus validus. 4 *
at different points

among the plants and an average taken. As the greenhouse was
supposed to be between 60-70° F., the readings were taken about
2:00 P.M. each day, merely to note any marked change in tem-
perature. It was found, however, that the variation was too great
and the readings too far apart to make the data of any value

1920] SNOW—DIAPHRAGMS 301
except to show that the change from air to water was accompanied
by a marked rise in temperature (fig. 1). This experiment indi-
cates that water may not be as important a factor in the growth
of Scirpus validus as temperature. This is probable because the
growing region is protected from the surrounding medium by a
very closely fitting sheath of scale leaves.

EFFECT UPON DISTANCE BETWEEN DIAPHRAGMS.—The distance
was measured between many diaphragms and the average taken.
As it was found that the diaphragm distance varied with the
distance from the tip, the culms were divided into decimeter
sections, so that the measurements taken in corresponding sec-
tions of the different culms, and in different sections of the same
culm, might be compared.

TABLE [I
DIsTANCES IN MM. BETWEEN DIAPHRAGMS OF Scirpus validus GROWN IN
ATER AND IN A
dm. - : n -s5 dm.
shuts Culm. no ioe tip hen tip om tip hex tip tip
Ae: Re OL a es CM dais des een ame ae 4.8 4.6
ese Se dala lew incas 2.6 peel ee is AE eee rh SME eee
E 80 8.2*
Piece ye Boe a cheater 2.7 2: 4-4 3.0°
2S oes Aes ees
ees eee lies mea Be PCG S Porn tees yO ty 36 See ee
Peg ae 1.6 BOO Oe eis yc es eee ee eee
x 3.0 3.85T $:Ot heise ee
lt Sea Pe ere ug Cee eerries Fae ae es rere ye coy ae
Nia Be ee icy a re ae ee eee os

* Two chambers in same section. + May extend over decimeter boundaries.

In table III the heavy type indicates parts grown in water,
and the remaining figures indicate those grown in air. Read
horizontally, the variation in a single culm, from tip to base, may

€ seen. Read vertically, the variations in the same region of the
different culms are shown. As it was impracticable, from the data
at hand, to calculate the rates of growth for the decimeter regions, it
was not possible in this experiment to correlate the rate of growth
with the distance between diaphragms.
EXPERIMENT 5

It was shown in experiment 4 that temperature, control was

very necessary; therefore in April 1916 experiment 5 was set up

302 BOTANICAL GAZETTE

[APRIL

in the greenhouse of the University of Chicago, using plants from
the material started at the Missouri Botanical Garden in the fall.

_ VARIATIONS IN RATE OF GROWTH AND
UNDER

TABLE IV

UCTURE OF CULMS OF oi ad validus
DIFFERENT aires OF MOISTURE AND HE

ge Sag D
. whi istance
mn G No. Tempera-
Culm no.| (mm. from | °h@58¢, | (mm. per xe of Fg bid between | layers of | Medium | ture
Pp) : day) phragms isades C.
from tip)
2-27. fore] 4+ I 1.2 2
172-210 8.33 5 oe Wag) RETR ed Water 35
Bau: 210-247 8.75 | Manyt I 2.5 2-0
247 . . eee
247-290 6.14 | Many I-2 ea ° Air 3°
o- 22.50 4 ; id cia
13 22.00 4 I-2 3. 2 ; °
Ba 142-172 30.00 4+ 2 3-4 2 Aug 24
240-27 7O.00 2:0) “frie dees
205 iva sadre neaese®
290-320 10.00 Many 3 3.2 O° Air 21
200-2 18.00 br ea Pear ties =
205-290. 55.00 Es ees Bee
5g 310-350 00 4+ I 3 es 2 Water 35
400-450 21.66 4.270 Ave
500-550 20.00 O20 Shakes wae
50- go. m 15-33 4+ I 1.4 2 Water 35
pie 8.33 4+ I 1.8 2
fat oe Peet Haran nese 27.00 Pe tiles eee nes 16
Le 40* : “Oy Seg epee es Water
aca. siping Cepia a AO 29.50 4+ I 2.4 I
304 Ki Getneee mee os
310-350 5.00 4+ I 2.8 I } Air 16
50 20.00 SS Rees
100-140. . 17.50 4+ I r.8 Tt Air 16
169 casen es ergs ateaeeo .
200-240 20.50 pe Gee re
260-300 age ig SeahS: Water 16
BA 4... -1390-S70". ede cies cies 23.25 | Many 1-2 3.5 2
BU Ee ee he ee Noa s Ces blend o Pek obese eer ees .
400-440 foe] EE ke ne eee
500-540 i 00 a pares Water 3°
600-630 |. 24.00 eae ee Oe
DOs). be PA 13.60 | Many 1-2-3 6.r ° Water ar
Le eh ag es ee AEs bo bee
872-920 7.00 | Many 1-2-3 6.4 °° Air a=
60-110 18.00 at 1(?) 1.7 1-2 (| Air alts
BI a eee aks ee EE os ede de wees oe A
125-175 oo ? ‘ 2
DD 7. 50. Hs 50 acy ct ae 2 Water ar*
400-4507, ee ees} 3-0 weeeee
508 sass eeEvhet nl “e
515-565 16.66 | Many 1-2-3 3-4 2 Water
44> 74 00 : 2 22%
DD8.... re oe aes 21.50 pat pos ps 2 they :
WO Pe Ee os a ee ete ae pee ee
200-250 18.66 ree x 2.7 2 Water 16
* Not observed for a period of 4 da wage
saatpigne period 4 days. : ee a ae + peal

> hal
ones.

1920] SNOW—DIAPHRAGMS 303

The thermostats were kindly loaned by the Chemistry Depart-
ment, and were regulated by Captain de Klotinski. The higher
temperature vessel was kept within a degree of 35° C. for two weeks,
and for the remainder of the experiment practically at 31°C. In
the low temperature vessel a coil of pipe, carrying a stream of
cold water, kept the temperature close to 15° C. for the first two
weeks, and for the rest of the time about 16°C. The temperature
in this vessel was not quite so constant as in the higher temperature
thermostat, because of the varying water pressure. A third set
of plants was allowed to grow without temperature control. When
the change to air was made, the pots were transferred to beakers
| TABLE V _
RELATION BETWEEN RATE OF GROWTH AND DISTANCE BETWEEN DIAPHRAGMS IN
Scirpus validus

Change Culm no. Rate Distance

E2 Decreased Increased

water t6 aro ch tees B4 Decreased Increased
: DD 3 Decreased Increased

AA 3 Increased Increased

Gt Or Weller i {oD 7 Taceessed Increased
Low to high temperature.......... AA 3 Increased Decreased
E3 Increased it

High to low temperature.......... es ; Tlecscaned Sa
8 Decreased Increased

sunken to the rim in the water of the thermostats. Water was
poured into the beakers to within an inch of the surface of the
soil. The tops were covered with two pieces of glass, allowing the
culms to project between them, and the crack was plugged with
cotton wool. Close observation showed the temperature in the
beakers to be practically the same as that of the water outside.
Measurements were taken every 24 hours, and the rate of growth
given for a region was usually the average for several days, thus

ating the questioned stimulating effect of the change (1, 9,
to, 14). At the end of the experiment longitudinal and cross
Sections were made in the regions grown under the different condi-
tions. The cross-sections were usually made at one end of a region

304 BOTANICAL GAZETTE [APRIL

and the rest cut longitudinally, and therefore the results given
in table IV are obviously not for exactly the same spot.

The number of changes was insufficient for reliable conclusions;
also it must be remembered that under normal conditions there
is a general tendency for the distance between diaphragms to
increase from tip to base (see also B 3). Certain indications,
however, are summarized in table V.

DISCUSSION AND CONCLUSION

GrowrH.—Region—So far I have found no reference to the
region of growth in the stem of Scirpus. PFEFFER (10) refers to
the basal region of growth in the leaves of Canna and Tulipa and
in the internodes of grasses, and states that the ‘‘length of the zone
is always small.” He also mentions the careful protection of this
zone. The same statements may be made for the zone of growth
in the Scirpus stem; the extreme narrowness of the zone, however,
is rather surprising. Growth in diameter was not studied.

Rate.—The results of the experiments were not perfectly har-
monious; but in general there seemed to be a tendency toward an
increase in rate with a change from air to water, and a decrease
with the reverse change. It seems probable, however, ape temper-
ature was a more important factor than water.

DIAPHRAGM DISTANCE.—From a study of table III it is evident
that the variation between culms growing under the same condi-
tions was greater than that between culms growing under differ-
ent conditions of air and water, thus eliminating water as a direct
factor in determining the distance between diaphragms. Its indi-
rect effect was studied in experiment 5, and although the data were
too scanty for positive statements, certain facts are rather signifi-
cant. As there is a normal tendency for the diaphragm distance to
increase from tip to base, the cases of increase after a change in
environment may not be significant. Two cases of decrease
occurred, however; one accompanying a change from high to low.
temperature, and the other following the reverse change. This
would eliminate the temperature change as the direct factor.
The fact that both of the cases of decrease in distance were assocl-
ated with an increased growth rate is the important point. Also,

1920] SNOW—DIAPHRAGMS 305

of the 29 cases of a change in rate of growth and diaphragm distance
shown in table IV, 19 (64 per cent) showed an inverse relation
between the two; 9 (24 per cent) showed a direct relation; and in
3 cases (10 per cent) an equal distance went with an increased rate.
When we remember that the normal tendency is to increase the
distance from tip to base, these last three cases really show an
inverse relation which, added to the 19 preceding, make 22 (75 per
cent) which show an inverse relation. Of these, 14 (49 per cent
of total) show an increase downward, which coincides with the.
normal tendency, while 8 (27 per cent of total) show a decrease
downward in opposition to the normal tendency, and therefore
the more significant. These confirm the indication shown by the
49 per cent, and tend to establish an inverse relation between rate
of growth and distance between diaphragms.

This is not what one would expect if the distance between dia-
phragms is considered to be brought about by the excessive growth,
or stretching, of the intervening tissues. It is what one would
expect, however, if, as was suggested in a former paper (13), dia-
phragms are due to certain cells retaining their power of division
and growth, while those above and below them lose this power
and are drawn out into arachnoid cells by the growth of the sur-
rounding tissues; and also if the formative activities show a
gradient from beginning to end of the growth of the stem. This
Suggests several interesting questions. Is there such a formative
gradient ? Would the respiration test show a gradual decline in
metabolic changes, or would it follow the growth curve? Is. it
possible that, in averaging the diaphragm distances in a region, a
shortening, corresponding to the rise in the growth curve, was over-
looked? Is the peak of the growth curve due wholly to a stretching
period? If so, would this stretching counterbalance the tendency
to shorten the diaphragm distance with the rise in the growth curve ?

AIR CHAMBERS.— Scirpus validus appears to start with four
large chambers and a number of small ones. As the culm grows,

€ small ones increase in size, until many nearly equal-sized
Spaces are the result. The different culms may pass through these
Stages at different rates; therefore the same regions cannot be
compared. Only two cases were noted in which a rather rapid

306 BOTANICAL GAZETTE | [APRIL

increase in the number of spaces occurred; in one, following a
change from air to water, there was a marked increase within a ~
distance of 15 mm.; in the other a noticeable increase occurred
within 9 mm., following a change from low to high temperature.
From these experiments there is no clear evidence that either water,
temperature, or rate of growth has any effect upon the number or
size of chambers produced.

PARTITIONS BETWEEN AIR CHAMBERS AND OUTER WALL OF STEM.
—The changes in environment used in these experiments appear
to have no effect upon the regular course of development of the
partitions, which seems to be an increase in the number of layers
from one to three. No observable difference could be noted in the
outer wall of the stems.

PALISADE LAYERS.—The curious banding, which is sometimes
seen in Scirpus, occurred in experiment 5. The albescent spaces
and the basal region contained no palisades. The dark green
portions contained two layers of palisades, and the pale green
spaces one layer, or two with only part of the cells chlorophyllous.
The environmental changes in the experiment seem to have no
effect upon the development of palisades, and cannot be held
responsible for the banded appearance.

Reduced atmospheric pressure
EXPERIMENTS

During February 1916 a series of experiments was started in
the temperate house of the University of Chicago, to test the
effect of low atmospheric pressure upon the air chambers of water
plants. The apparatus is shown in fig. 2 and described in the
legend. The temperature of the house was controlled by the
general heating system, and a recording thermometer showed a
variation of a degree about 20-21°C. The barometric pressure
was obtained in experiment 1 from the records of a government in-
strument outside the greenhouse, and the figures were reduced to
metric readings at 21°C. In experiments 2 and 3 the pressure read-
ings were obtained from the barometer in the Botany Building, and
corrected for temperature only. The pressure in the experimental

1920] SNOW—DIAPHRAGMS a 307

jar was read on the manometer. It varied somewhat on account
of the variation in the flow of the city water supply used to produce
the suction. Plants of Scirpus validus, selected from those started
in St. Louis, and Cyperus alternifolius (?), already growing in the
greenhouse, were used.

EXPERIMENT I

This extended February 4-14. The pressure varied between
10 and 20mm. of mercury. This pressure was chosen because air

Fic. 2.—Apparatus to test effect of low atmospheric pressure: bell-jar 1, control;
bell-jar : 2, experiment; under each jar a pan of water containing pots of Scirpus;
air entering at I and also around bottom of 1 (not sealed as was 2) passed out of 1 into
flask where narrowed tube retarded flow and bubbles indicated rapidity of passage;
in 2 air entered at bottom and escaped at top, thence through two catch bottles to
pump operated by city water supply; m, manometer; w, tube for watering 2.

at 20mm. pressure contains about as much oxygen as is dissolved
in water (8). Cyperus would not grow at this pressure, and
Scirpus alone was used. The culms were measured twice a day,
and, after the close of the experiment, longitudinal and cross sections
were made and measurements taken as in n the previous experiments.
Culms nos. 1 and 2 belonged to the control plant, nos. 3 and 4 to
the experimental plant. Fig. 3 and tables VI and VII give the

308 BOTANICAL GAZETTE [APRIL

results obtained. In fig. 3 the peak in the pressure curve at
5:30 (February 7) was due to the fact that the pinch-cocks were
left open for a short time during watering. The second peak

TABLE VI ~*

GROWTH AND STRUCTURE OF Scirpus validus: CULMS I AND 2 GROWN AT ATMOSPHERIC
PRESSURE; CULMS 3 AND 4 GROWN AT 10-20 MM. PRESSURE

WALLS IN MM, SPACES
D GROWTH
Curm no.| REcIoN or pow (MM. PER
Outer Inner Large Small —e —
5 ea Me Fi oy cele a Eas hoe oe vottone vies Piece aetal oes Fare sb aoe
yee ie 45-71 fore) 0.168 | 0.050 4 6 2.36 0.51
eek Fae Mor ghs fers hr leer cox les sfeablinerars Pica acy gent Briere DE PIEAE YM 8
AAG, 45-71 by 0.134 | 0.054 4 8 3.92 0.32
peer MIO eh es oh ok es ok os ella ee co ee ee
eo 71-100 | 1.89 0.156 | 0.050 10 2.55 0.85
Load 7I-100 | 2.25 0.703. 6, 15 9 3.50 0.53
Mee Sas 7i~100 | 1.55 ©.119 | 0.052 9 4.05 0.49
5 erg se |esediiedl Gdetad Gooeooes GoCcCcnn Cencong Bormann cect ces ae kay
ps PS ie 100-124 | 2.15 ©.108 | 0.050 7 8 3.10 1.35
5 nee 100-124 2.38 0.150 | 0.050 15 Yj 5.60 0.51
Pape Spee 100-124 1.73 0.103 0.090 12 7 3.90 0.21
Poe. sh Be-Ig§ | 250 0.050 | 0.065 | 17 16 “G08 shigtaes
Cre 24-175 | 2.25 0.128 | 0.070 7 9 3.73 I.39
eenee 124-175 | 2.50 | 0.113 | 0.090] 16 7 5.18 0. 36
TABLE VII
INCREASE IN DIAPHRAGM DISTANCE IN MM.
Region | No. 4 over no. 2 No. 3 over no. 2
Oi aa 2 ici Ae Ee Babar S O. BG e re eae me tics <
hg to Ae Aa AR ay 1.50 9.95
et RE a Rae °.71 2.41
cP ee Gr Pee MN ee ET Ea ee Pe Sym 1.45

cannot be definitely accounted for by the data at hand. It is
very probable that in these two cases, as well as in two others,
an adjustment was made at once, but there are no records of the
fact, such as occur later. The dotted line, therefore, is probably
the more correct one. ;

1920] SNOW—DIAPHRAGMS 309

EXPERIMENT 2
This experiment extended February 14-28. It was set up in
the same apparatus as was experiment 1; the pressure, however,
started at 35 mm. and varied between 20 and 40 mm. of mercury.
Cyperus would not grow. at this pressure; consequently the results

ep PS

ko

> fe

I
|
I
|
'

Growth in mm. eer hour,
hb

2

Bar. Pr,
| ao ae Se a

\

/

rd
|

of mMereury.

——.
e——]

# 2 2 2 4 3

4
=

oes
ee Se Eee oo

Feb!o Feb! ‘eb.

=—}”_
~ a /

Pressure in “gia mm...
-

ps es
\

30 30 7
Feb. Fet.b Fab. Feb. Feb.

Fic. 3.—Growth curves: solid line, no. 2; dotted line, no. 3; broken line, no. 4;
curves 2 and 3 cease when culms reached top of jar.

are given for Scirpus only. The quantity of air passing through the
jars was measured and found to be about 1500-2100 cc. per hour.

At times it exceeded this amount, but the flow was kept fairly con-
stant. The experimental culms were nos. 3 and 4, and the con-
trols nos. 1 and 2. Tables VIII and IX give the results.

310 BOTANICAL GAZETTE _ [APRIL

TABLE VIII
GROWTH AND STRUCTURE OF Scirpus validus: CULMS I AND 2 GROWN AT ATMOSPHERIC
PRESSURE; CULMS 3 AND 4 GROWN AT 20-40 MM. PRESSURE

WALLS IN MM. SPACES
D cm| GROWTH
Cutm No.| REGION oe DISTANCE | Gi. PER
Outer Inner Large Small sl orcas Hour)
5 ape ee O- 10°} 0,885 | 6.14 0.05 3 Bers, oy fo He pen eee
~ age eae oO 10} 0.895} 0.11 0.04 4 ial REE EC Pa
ae eoeae o- 10 O10 | OF EE 0.05 2 Pere, Crm aurea Got >
PS eG oI I.o10 0.08 0.05 4 Oo et bee eee
Be cals $O-- 30 fF, 260%) 0,17 0.03 4 4 1.630 | 0.48
> ede ESD Io- 30] 1.775 | 0.14 0.04 4 9 DOSS ee
Boake 1O- 30 | 1.545. | .-0.13 0.05 4 7 m. 170. Ors7
Ae Io 30] F.550 | 0.14 ° 5 II 3.100 | 0.24
eyes 30- 65 | 1.450] 0.18 | 0.09 Pega 1.750 | 0.68
are eeks go> O05 12.330 |. 125 0.06 12 fe) 2.250 cee
Sisk. 30- 65 I.gI0 | 0.14 0.05 4 8 . 400 55
7 Ne SN, 30- 65 E. oO. 13 0.05 5 14 2.950 0.49
baer Hee a Geeta bs 80600: O 5A se ea 4 8 2.320 0.83
ern ne 65-105 | 2.000} 0.12 0.06 16 10 2.030. |abetee.
ees G5-105 | 2.455 | CO. 45 0.07 4 15 2.980 | 9.57
So et GS-165 | 2.066 |. 6:33 0.09 5 16 3 9.47
Peaks TOS TSO ow sce elon > ae oe-afus aa wl eeeo stir sc eee nlse Cet cutie seme
be nee JO5-130.; 3.0401 O13 0.05 18 10°) 8 2006 be a cepa ce
eae 105-130 | 2.255 | 0.15 ° 4 15 3.270 | 0.83
Pe setaged 105-120 | 1.595 |. 0.11 0.07 II 12 9.95
& lm , before e experiment A + 11 1 rp. trol
the Mtn el pie aia with this pay: in mind,
TABLE IX
INCREASE IN DIAPHRAGM DISTANCE IN MM.
Region No. 3 over no. 1| No. 3 over no. 2| No. 4 over no. 2
RO 80% 0.54 08 3.915
Sa a aia 8 1.65 1.250 0.800
OG OIOS oy ee ks 0.66 0.950 1.150
cc gee ee eee Re Ra ean ee 0.970 1.180

EXPERIMENT 3
This experiment was set up on February 28 under the same
conditions as experiments 1 and 2, except for the pressure, which
was kept between 60 and 80mm. of mercury. The experiment
was discontinued on March 4 because the culms had reached the
top of the jars. At the end of the experiment the manometer

1920] SNOW—DIAPHRAGMS 311
showed a trace of moisture, and was found, upon being tested with
the air pump, to register 2mm. too low. As the variation in
pressure had been 20 mm., it was not thought necessary to correct

TABLE X

GROWTH AND STRUCTURE OF nied Se validus: CULM I GROWN UNDER ATMOSPHERIC
PRESSURE; CULM 2 GROWN UNDER 60-80 MM. PRE

WALLS IN MM. SPACES
DIAPHRA'
Curm no.| ReEcton — DISTAN rag ah
Outer Inner Large Small HOUR)
este Gy eam : O57135.] > 2-85 0.130 | 0.058 7 17 2.50 0.62
2eeseee, O5-1S66 479 pa a2 (eee 4 15 2.36 0.52
Ae eg a ¥35°173' | 3:86 0:133 |, O:0051 12% 12 2.41 0.80
Bo oe, 135-173 | 1.95 0.135 | 0.082 7 15 2.20 0.89
TABLE XI
INCREASE IN DIAPHRAGM DISTANCE IN MM,
Region No. 1 over no, 2
30- 59* °.39
95-135 0.19
135-173 0.12
* * Before the experiment.
TABLE XII

F reateizabie . sorte validus

DIAPHRAGM DISTANCE AND RATE 0
UNDER REDUCED ATMOSPHERIC
Average distance
Experiment no. Culm no. — oe ee eae
pelea ge 2.96* 7.08"
Be oe Be i a aici 4.76 0.43
Be ee 3-96 0.32
| Saeco 1.90* 0.84
Bess ce ke Bots dower 2.96 0.6
45 ARs 3.18 0.44
Be ee 2.46* °.70*
eeu Ui sss dit ney a

L Ath

for this error. On the average 5 liters of air passed through the
apparatus per hour. Culm 1 was the control and culm 2 the
experimental one. Tables X, XI, and XII give the results.

312 BOTANICAL GAZETTE [APRIL

Experiment 3 consisted of only two culms; therefore the dis-
agreement found in the other experiments between the culms in
the same pot is not noticed here.

DISCUSSION AND CONCLUSIONS

ATMOSPHERIC PRESSURE AND GROWTH.—Much work, with con-
flicting results, has been done upon the effect of varying degrees
of atmospheric pressure upon growth. There is a rather general
agreement that a certain decrease in pressure accelerates growth,
but a difference of opinion as to whether this is due directly to
diminished pressure or to a decrease in the partial pressure of the
oxygen (8, 11, 15), also whether increased growth in water is due
to decreased oxygen pressure or to some other factor.

Low pressure (10-20 mm. in experiment 1) seemed to have a
_ general depressing effect upon growth in Scirpus, as will be seen
in fig. 3 and table XII. The curve shows that this effect was not
constant, however, and that growth did not follow the variations
in pressure. In general there is greater growth in both control and
experiment during the day. The graphs for experiments 2 and 3
show this last point somewhat more clearly, and also show the
closer agreement of the two curves as the pressure in the experiment
was increased, but they are not sufficiently striking to merit inclu-
sion in this report. The power to grow fairly well with such a
small supply of oxygen evidently enables Scirpus to grow in very
poorly aerated situations.

DIAPHRAGM DISTANCE.—If low atmospheric pressure had any
effect upon distance between diaphragms, there would be a pro-
gressive increase, or decrease, in the experimental culms as com-
pared with the control, because there is a normal tendency to
increase the distance from tip to base. Tables VII and [IX show
that, while the experimental culms had a greater diaphragm
distance throughout than the control, this did not increase pro-
gressively, but varied in the different regions. In experiment 3,
however, the results were different. Before the experiment the
control had the greater diaphragm distance (1.61-1.22 mm.).
This persisted, but in a diminishing amount (table X1), which really
means a progressive increase in the experimental cu t is

1920] SNOW—DIAPHRAGMS 313

possible that the greater diaphragm distance found in the experi-
mental culms may have been due only indirectly to decreased
pressure, through its effect upon growth. In every instance
(except region 95-135, experiment 3) an increase in the diaphragm
distance was correlated with decreased growth rate. This agrees
with the results reported earlier in this paper.

NUMBER OF AIR CHAMBERS.—In reviewing the literature one
finds a rather general opinion that air spaces increase with the
amount of water in the substratum (2, 3, 7, 10, 12, 16). Recent
work by Fotsom (6) on Ranunculus, however, has shown that
while the aerenchyma of the stem varied directly with the amount
of water in the soil, that of the root showed no such constant
relation, and in some cases even varied inversely. Various func-
tions have been attributed to the air-containing tissue by different
authors. Some consider it as “floating tissue’’ (2, 9, 10), while
others consider it a means of oxygen supply, giving a lack of oxygen
as its direct cause (7, 10, 12). On the other hand, WieLER thinks
it has no function, and attributes its formation to the direct stimulus
of water contact. Drvaux (5) thinks that the hypertrophy of
lenticels found in water and moist air is due to a checking of the
transpiration, a factor which apparently has not been tested in
connection with the formation of air spaces, although suggested
some time ago by CowLEs (4).

If low oxygen pressure is the cause of increased air spaces, it is
rather strange that in Fotsom’s experiments the roots, which
under any condition are farther from the oxygen supply than the
stem, should show either inconstant increase or a positive decrease
in aerenchyma with increase in water content of the soil. In
experiment 3 there was a small increase in the total number of
air chambers in the experimental culm, at the same time that the
control remained the same. On the other hand, experiments 1
and 2 give evidence of a greater variation in total number of spaces
and in their uniformity in size between the culms under like condi-
tions than between the experiment and the control. Contrary to
expectation, therefore, low atmospheric pressure appears to have
no effect upon these two characters in Scirpus.

314 BOTANICAL GAZETTE [APRIL

INNER AND OUTER WALLS.—The records show a close similarity
in the width of the outer solid tissue of the culms of the control
and of the experiment. This is also true for the partitions between
the chambers.

PALISADES.—In experiment 1, one control culm developed one
layer of palisades and the other two; while in experiment 2 the
same thing occurred in the experimental culms. In the third
experiment both culms had two layers. Atmospheric pressure
seems therefore to have no effect upon palisade tissue.

EXPERIMENT 4

This experiment extended from April 11 to May 10. The
apparatus used was the same as in the previous experiments,
except that a tube dipping into a dish of mercury was used to
indicate the pressure instead of the regular manometer. Cyperus
alternifolius (?) was used in this and the following experiment
instead of Scirpus. The time was divided into five periods, dur-
ing which an effort was made to keep the pressure at 1/6
atm. (130+mm.), 1/3 atm. (250+mm.), 1/2 atm. (380+ mm.),
3/4 atm. (570+ mm.), and 5/6atm. (630+ mm.) respectively.
The pressure varied very greatly, probably because the city water
supply varied more at this time than earlier in the year. Culms I,
2,6, 7, and 8 were the control, and nos. 3, 4, 5, and 9 the experi-
mental culms. Nos. 1, 2, 3, and 4 started before the experiment
and were not used in the comparison. Culms 3 and 4 when
placed at 1/6 atm. grew very little and ceased growth in 3-4 days.
At the end of a week the pressure was raised to 1/3 atm., but with-
out effect upon these culms. Toward the end of this period no. 5
started to grow slowly. At the same time no. 6 started in the
control. With the rise to 1/2 atm. no. 5 grew better, but still kept
behind no. 6. The rates approached each other very closely when
the pressure rose to 3/4 atm. During this period no. 7 began to
grow in the control, and as it followed very closely the growth curve
of no. 6 (which had grown very tall) it was used for comparison
with no. 5. At 5/6 atm. no. 7 still maintained a higher rate than
no. 5, which by this time had about reached the limit of its growth.
About the middle of this period no. 8 started in the control, and no. 9

1920] SNOW—DIAPHRAGMS 315

in the experiment, and the graphs for nos. 7, 8, and 9 are so nearly
alike that it is evident that this amount of pressure has the same
effect on the growth of Cyperus as full atmospheric pressure.

After the experiment was over, cross-sections were made at the
same distances from the top in the two sets of culms, but, no evi-
dence that diminished pressure had any effect upon the air spaces
could be observed.

EXPERIMENT 5

This. experiment was set up May to, using the same apparatus
as in the last experiment. The pressure was kept for 3 days at
about 1/2 atm. (380+ mm.) and for 2 weeks at about 7/10 atm.
(530+ mm.), after which it varied around 1/3 atm. (250+ mm.)
for 6 days. Growth was not measured, but after May 31 cross-
sections were made. A careful study of these show that at 30 mm.
from the base the experimental culm was a little more lacunose
than the control, at 50 mm. still more so, but at 70 mm. it showed
less difference. At 95 mm. the experimental culm ended in the
usual tuft of leaves, while the control grew much higher, and at
95mm. showed a structure exactly like that of the experimental
culm at 50 or 70mm. The shorter culm evidently had not differ-
entiated as much as the longer one, and the difference in the
Sections was therefore only apparent and not due to the effect of
diminished pressure.

From these two experiments one must conclude that, although
atmospheric pressure reduced below 630+ mm. had a retarding
effect upon the growth of Cyperus, there is no evidence that it had
any effect upon the air spaces.

Summary

1. The zone of growth of Scirpus validus is very short, possibly
2-3 mm.

2. The direct contact of the surrounding medium with the
gtowing region is prevented by a closely fitting sheath of scale
leaves.

3. In these experiments \ the rate of growth, in general, was
increased by a change from air to water, and from low t to high

316 BOTANICAL GAZETTE [APRIL

temperature; while the reverse changes resulted in a decrease in
e rate.

4. Temperature seemed to be a more important factor than water.

5. The increase in diaphragm distance which followed a change
from water to air, and from high to low temperature, did not
seem to be sufficiently great to be considered a direct result of the
change, inasmuch as there is a normal tendency to increase from
tip to base.

6. There appeared to be an inverse relation between diaphragm
distance and rate of growth.

7. Environmental conditions may influence diaphragm distance
by their effect upon growth.

8. A decreased growth rate would indicate a lowering of the
vital activities of the plant, and would result in the formation of
fewer diaphragms, thus increasing the distance between them.

9. This decreased vitality was shown normally in the decrease
in growth rate toward the close of the growth period, and was
accompanied by an increase in diaphragm distance.

10. This plant grew fairly well under 10-20 mm. pressure,
while under 60-80 mm. pressure there was almost as good growth
_ as under normal pressure.

11. There appeared to be an increase in diaphragm distance at
low Pressures. Apparently this was due to the retarding effect of

ished pressure upon growth.

12. Lowered pressure appeared to have no effect upon (x) the
total number of air chambers or their size, (2) the thickness of the
mass of tissue on the outside of the stem or of the partitions between
the chambers, and (3) the number of palisade layers.

13. These experiments lead one to conclude either that water
with its low oxygen content is not the direct cause of the air spaces
in aquatics, or that Scirpus validus is a very non-plastic organism,
retaining its characteristic growth and structure under wide varia-
tions in environmental conditions.

14. A lowering of the atmospheric pressure below 630+ mm. had
a retarding effect upon the growth of Cyperus alternifolius (?), but
there is no evidence that it had any effect upon the air spaces.

WELLESLEY CoLLEGE

WELLESLEY, Mass.

1920] SNOW—DIAPHRAGMS 317

La)

-

=

*

oo

LITERATURE CITED

. Asxenasy, E., Uber einige Beziehungen zwischen Wachstum und Tempera-

tur. Ber. Deutsch. Bot. Gesells. 8:61-94. 1890.
Bonpors, G., Contribution a l’étude de influence du milieu aquatique sur
les racines Pe arbres. Ann. Sci. Nat. Bot. [IX 18:1-24. 1913.

. CosTANTIN, J., Recherches sur l’influence qu’exerce le milieu sur la struc-

ture des racines. Ann. Sci. Nat. Bot. VII 1:135-178. 1885.

Cowtes, H. C., Textbook of botany. Coulter, Barnes, Cowles. II.
American Book Co. rgrt.

Devaux, H., Recherches sur les lenticelles. Ann. Sci. Nat. Bot. VIII
1221-240. 1900

Fotsom, D., The influence of certain environmental conditions, especially
water mech: upon form and structure in Ranunculus. Phyisol. Res.
2:209-276. 1918.

- Jost, L., Ein Beitrag zur Kenntniss der Athmungsorgane der Pflanzen.

Bot. Zeit. 45:601-606, 617-627, 633-642. 1887.

; Pages a J., Uber die Wachstumsreize. Beih. Bot. Centralbl.

26:7-1409.

. PEDERSEN, "R., Halen Temperaturschwankungen als solche einen un-

giinstigen ar auf das Wachstum? Arb. Bot. Inst. Wiirzburg

1: 563-583. 1

PFEFFER, W. Gray Physiology of plants. Oxford. 1

SCHAIBEL, F., Physiologische Experimente iiber das Wachstum und die

Keimung einiger Pflanzen unter verminderten Luftdruck. Fiinfstiicks

Bei. Wiss. Bot. 4:93-148. 1900. °

Scuencu, H., Uber das Aérenchym, ein dem Kork homologes Gewebe bei

Sumpfpflanzen. Jahrb. Wiss. Bot. 20:526-574. 1889.

Snow, L. M., Contributions to the knowledge of the diaphragms of water

plants. I. Scirpus validus. Bor. Gaz. 58:495-517- 1914.

— R., Turgor and temperature on growth. Ann. Botany 9:365-402.
1895.

Wieter, A., Die Beeinflussung des Wachsens durch verminderte Partiar-
pressung den Sauerstofis. Untersuch. Bot. Inst. Tiibingen 1:186-282.
1883.

, Die Function der Pneumethoden und des Aérenchyms. Jahrb.
Wiss. Bot. 32:503-524. 1898.

LIFE HISTORY OF FOSSOMBRONIA CRISTULA
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 264
ARTHUR W. Haupt
(WITH PLATES XIV-XIX AND ONE FIGURE)

Fossombronia, according to SCHIFFNER (8), comprises 26 species
of world wide distribution. The genus belongs to the family
Codoniaceae of Cavers (2), which is, next to the Haplomit-
riaceae, the highest family of the anacrogynous Jungermanniales.
Fossombronia and its closely related genera Blasia, Noteroclada, and
Treubia are thalloid dorsiventral forms which show the beginnings
of genuine leaves corresponding to those of the acrogynous Jungert-
manniales, and represent, with the Haplomitriaceae, possible
ancestral forms from which the Acrogynae have been derived.

Fossombronia cristula was discovered and named by AUSTIN
(1) in 1868, who found it growing ‘“‘on damp sand in an unfre-
quented path’ near Batsto, New Jersey. For many years no
additional material was collected, nor was it reported as occurring
in any other locality in the United States. This no doubt was due
to the small size and obscure habitat of the species. In 1915
Evans (3) made a taxonomic study of F. cristula and stated that
specimens had been collected in Massachusetts, Connecticut, New
York, New Jersey, West Virginia, and Indiana. Lanp found the
species in 1914 in Porter County, Indiana, 2-3 miles east of Dune
Park, and a preliminary report of its occurrence in this region was
published by Hix (5) in 1916 from material furnished him by
Lanp. Ht also found plants growing in Lake County, Indiana,
3 miles east of Tolleston. In his paper the author incorrectly
refers to the species as F. crispula, which is not the name given it
by AusTIN.

Material

The material used in this study to illustrate the development
of the sporophyte was kindly furnished by Dr. Lanp from his
collection of 1914 from the Dune Park region. Additional plants
Botanical Gazette, vol. 69] ae

1920] HAUPT—FOSSOMBRONIA 319

were obtained by the writer from the same locality in 1917, about
a month earlier than Dr. LANp’s material had been collected, and
served to illustrate the development of the thallus and the sex
organs. The writer found F. cristula in this locality. growing in
cracks on fine, wet deposits of silt on the bottom of an almost
extinct lake. Hutt notes that “‘a favorite place of growth in the
Tolleston locality was vertical sides of holes left in the mud by the
feet of cattle.’ In the Dune Park region the plants are associated
in great abundance with Drosera longifolia.

Historical summary

The earliest detailed study of Fossombronia is that of LEITGEB
(7), who investigated F. pusilla, a European species. The author
made a very careful study of the origin and insertion of the leaves
and the development of the stem axis and mucilage hairs in the
region of the growing point of the thallus. The apical cell is
dolabrate, cutting off alternately right and left segments only.
The plants are mostly monoecious, and on those in which antheridia
are in greatest abundance, archegonia also occur to a limited
extent. In regard to the order of appearance of the sex organs,
the author says: ‘Aber ich fand haufig Sprosse mit véllig ent-
wickelten Kapseln, welche nach der Spitze hinwieder reichlich
Antheridien producierten.”’ The position of the antheridia and
archegonia is the same as that of the other species, and both
originate close to the apical cell. In regard to the development
of the antheridia it is stated that they deviate in no way from the
normal type, although no figures are shown to illustrate this develop-
ment. The venter of the archegonium is 2 cells thick before
fertilization.

The fertilized egg is elongated in the direction of the arche-
gonium axis, and divides by 2 horizontal walls, forming a tier of 3
superimposed cells, of which the lower forms the foot, the middle
cell the seta, and the upper one the capsule. The upper and lower
cells divide more actively than the middle one. The differentiation
of wall cells and sporogenous tissue in the capsular region occurs
early. The mature capsule is 2-layered; the inner wall forms
annular thickenings. At the apex the capsule wall is 3-layered.

320 BOTANICAL GAZETTE [APRIL

The author studied the germination of the spores; he notes that
a dolabrate apical cell is organized early, but he makes no state-
ment regarding the development of the leaves.

The most complete study of Fossombronia since LEITGEB is
that by Humpurey (6), who investigated F. longiseta, a species
occurring in California. The thallus reaches a length of 30 mm.
and develops genuine leaves like the other species of the genus.
The plants revive well after undergoing desiccation, and tuber-like
thickenings are formed on the stem in which fungi live. The
plants are monoecious, or by exception dioecious. HUMPHREY'S
‘account of the development of the antheridium is most interesting,
in that it departs widely from the usual Jungermanniales type.

The initial cell of the antheridium is somewhat larger than the neighbor-
ing vegetative cells, and is span distinguished from them by its deeper
staining qualities... . . Just previous to the first division the initial cell
becomes considerably Seat extending a third or more of its total length
above the surrounding cells. The first division results from the formation of
a horizontal wall which cuts off the stalk from the antheridium itself. Unlike
what occurs in the majority of the Jungermanniaceae, the next division,
instead of being vertical, is horizontal, thus dividing the antheridium mother
cell into two superimposed cells; whereas in Sphaerocarpus and Geothallus
another horizontal wall is formed, thus producing another cell, the two upper-
most dividing vertically to form the antheridium, while the basal cell, by @
series of transverse walls, forms the foot.

In Fossombronia the development thus far agrees exactly with that in
y avoshat ed and Geothallus, except that in Fossombronia only one horizontal

in the antheridium mother cell, the stalk arising from the
votes cell formed iby the first horizontal division. This basal cell later divides
horizontally, the uppermost segment becoming active in the formation of the
stalk, while the lower ordinarily does not divide again. Following
horizontal division of the antheridium mother cell are two vertical divisions
forming planes at right angles to each other and dividing the antheridium
into octants. The next division results in periclinal walls for each of these
octants, and there thus arise eight central cells and eight periclinal ones. . - - -

Judging from the development of the antheridium, Fossombronia is more
closely related to Sphaerocarpus and Geothallus than to the higher forms of
the Jungermanniaceae. . . . . Thusit seems that Fossombronia longiseta forms 4
connecting link between such forms as Sphaerocarpus and Aneura.

The development of the archegonium presents no striking
difference from the usual situation; 6 neck canal cells are formed

1920] HAUPT—FOSSOMBRONIA 321

and the venter becomes 2 cells thick only after fertilization. The
first division of the fertilized egg is transverse, the upper segment
forming the capsule and the lower forming the foot. The second
transverse division separates the segment which is to form the
capsule from that which is to form the seta. A third transverse
division occurs in the uppermost cell, resulting in a tier of 4 super-
imposed cells. After this 2 vertical walls appear at right angles to
each other, followed by periclinal walls in the upper segment.
The author states that the capsule wall is normally 2 cells thick,
but shows a wall composed of 3 layers of cells in his fig. 61. Both
layers of the capsule bear annular thickenings. The mature elaters
reach a length of 150-300 w, and are provided with a double spiral
ickening. Dehiscence is by means of four valves.

HUMPHREY’s account of the development of the antheridium
is vague, especially because no references to his figures are given
in the description. Two interpretations are possible. If the
second wall in the antheridium initial is transverse and is followed
by vertical divisions in the two uppermost segments, the develop-
ment is exactly like “‘what occurs in the majority of the Junger-
manniaceae,” as his figure representing this stage is the same as
my fig. 11, except that the first vertical divisions result in an
octant of cells instead of the condition shown in fig. 15. If
Humpurey speaks of the initial as the dorsal segment resulting
from the first transverse division of the true initial, then the third
wall in the true initial is transverse instead of vertical, but the
Situation according to this interpretation would be precisely the
same as that in Sphaerocarpus.

At any rate, HuMPHREY’s series of stages are not sufficiently
close to convince one that the situation in Fossombronia is radically
different from that characteristic of most of the other Jungerman-
niales, and inasmuch as no mitotic figures are shown to prove the
€xact sequence of the first divisions in the initial, except for his
figures of cross-sections, it is possible to interpret the development
of the antheridium of F. Jongiseta as strictly normal. If HuMPHREY
is really familiar with the development of the antheridium in the
majority of the Jungermanniales as well as that of Sphaerocarpus,
and the difficulty in interpreting his account is merely the result

322 BOTANICAL GAZETTE [APRIL
of his obscurity in explaining the situation, the development of
the antheridium would be as represented in fig. r.
Investigation
THALLUS

The vegetative body of Fossombronia cristula is minute, being
only 2-4mm.inlength. It is creeping and semi-prostrate, although —

Fic. 1.—Above, F. longiseta; below, F. cristula

the stem tips may occasionally be more or less ascending. The
branching is rather profuse and is strictly apical. The stem shows
no indication of a conducting system as in Pallavicinia and Sym-
phyogyna. The plants form dense matlike growths over the sub-
stratum, and are attached by means of long, violet-red rhizoids
(fig. 6). The plant is an annual, developing in the early summer
as soon as its habitat becomes sufficiently dry; in the Dune Park
region the spores are ripe by late September or early October.

£920] : HAUPT—FOSSOMBRONIA 323

Growth of the main axis and branches is by means of a dolabrate
(zweischneidig) apical cell (figs. 4, 5), with which are associated
simple ventral mucilage hairs (figs. 7, 22) which may be several
cells in length. CAvERs (2) states that each lateral segment of the
apical cell of Fossombronia, by 2 transverse divisions, forms 3
horizontal cells, the upper and lower cells developing the stem and
the middle cell forming a leaf, according to the same method as
occurs in Blasia.

The leaves are borne in 2 dorsal rows; they are more or less
erect, obliquely inserted on the stem, closely imbricate, and pale
green (fig. 2). The ventral surface of the thallus is entirely devoid
of leaves. Hut (5) notes that the leaves become paler and whitish
with age. The shape of the leaves varies from somewhat quadrate
to slightly obovate; they are very crisped and have subentire
margins which occasionally bear a few feeble crenulations at the
apex.

The cells of the stem and leaves contain numerous small pe-
ripheral chloroplasts. Considering the small size of the plant, the
cells are relatively large. Mitotic divisions were very rare in the
material studied; the best mitosis seen was that of a late metaphase
in the apical cell (fig. 3). From a study of this figure it was
estimated that the haploid number of chromosomes is 4, although
this fact cannot be stated with absolute certainty, as no other
Stages of mitosis equally favorable for chromosome counting were
found.

There can be no doubt that the 2 rows of lateral outgrowths
from the axis of Fossombronia represent true leaves. The develop-
ment of such a plant body from a form like Pallavicinia Lyellii,
which consists of a midrib with thin, one-layered lateral wings
slightly undulate on the margins, is very logical. Symphyogyna
aspera might be taken to illustrate a second evolutionary stage,
as in this plant the wing margins of the thallus are distinctly lobed.
Among the Codoniaceae, Blasia represents a still farther advance,
as in this case the lobes are even more distinct and regular, and
the step from this condition to that of Fossombronia is pertectly
natural. The plant body of Noteroclada is still more distinctly
leafy, and in Treubia the axis bears 3 rows of leaves formed by an

324 BOTANICAL GAZETTE [APRIL

apical cell of the pyramidal type. This series, of course, is not a
truly phylogenetic one, but represents a sequence of hypothetical
stages through which the Jungermanniaceae acrogynae have
probably passed in the course of their evolution.

SEX ORGANS

The plants of Fossombronia cristula are monoecious; the sex
organs are dorsal and scattered over the stem in the leaf axes.
The antheridia and archegonia are more or less separately grouped,
but both kinds may occur in the same leaf axis (figs. 7, 8). There
is no time relation in the appearance of the sex organs; antheridia
may precede or follow the archegonia, and this sequence may be
repeated several times in any order.

The question of the differentiation of sex in F. cristula is an
interesting one. Inasmuch as the thallus is bisexual and there is
no definite sequence of antheridia and archegonia, sex must be
determined at some other point in the life history than at the
reduction division, or at one of the divisions of the apical cell.
Up to the formation of the first horizontal wall in the initial, no
differentiation of sex has occurred. Moreover, as the first vertical
wall determines the kind of sex organ to be produced, sex probably
is determined at the division concerned with the formation of the
first gametogenous cell. It would be an interesting experiment to
attempt to control sex in this plant by external conditions, as the
sex organ initials probably contain the possibilities of both sexes.

ANTHERIDIUM.—The antheridia develop in small groups, either
separately or with archegonia, in acropetal succession from the
immediate dorsal segments of the apical cell. Each group comes
to lie in the axis of a leaf which acts as an involucral organ, protect-
ing the group from behind. There is no special involucre developed,
as in many of the strictly thallose Jungermanniales, for, as the
writer has pointed out in his study of Pallavicinia (4), the anther-
idial involucre of the thallose forms is strictly homologous with the
involucral leaf of the foliose forms. ne

In the development of the antheridium of F. cristula, the
initial becomes papillate (fig. 9), and by a transverse division 4
basal cell is cut off from an outer cell. A second transverse wall

1920] HAUPT—FOSSOMBRONIA 325

then divides the outer cell into equal segments, forming a primary
stalk cell and a primary antheridial cell (fig. 10). The next
division is vertical in the antheridial cell, and is usually followed
by a similar division in the stalk cell (fig. 11), which may be parallel
with or at right angles to the vertical wall in the antheridial cell
(figs. 13, 14). Two periclinal walls then appear in the antheridial
cell (figs. 13, 14); their relation to the first vertical wall may best
be seen in a cross-sectional view (fig. 15). Two additional periclinal
walls, which come in at right angles to the first two, complete
the peripheral layer of 4 primary wall cells, which are thus separated
from the 2 central spermatogenous cells (fig. 15). The cell contents
of the primary spermatogenous cells assume a much darker stain
than the contents of the primary wall cells or the cells of the
stalk; in no cases were periclinal walls seen in the stalk cell. Thus
there can be no doubt that the antheridium develops according to
the usual method found among the anacrogynous Jungerman-
niales, and not as HumpHrey has described for F. longiseta.

Occasionally a transverse wall may appear in the stalk cell
before the periclinal walls are formed in the antheridial cell (fig.
12), but usually the divisions of the stalk cell follow the formation
of the primary wall cells. Sometimes, also, the first division of
the stalk cell may be transverse instead of vertical (fig. 16).
Further development of the spermatogenous tissue is like that of
the other Jungermanniaceae anacrogynae. The stalk of the
mature antheridium is commonly 4 cells in length, and invariably
shows 4 cells in cross-section. ‘The sperms are very small, slender,
and extremely coiled before their escape from the antheridium.
Each bears a pair of long terminal cilia. The sperms are produced
in pairs from the sperm mother cells, but their development is not
favorable for critical cytological study because of their extremely
small size.

ARCHEGONIUM.—The archegonium originates from a papillate
initial which may be formed from the first segment of the apical cell
(figs. 21-23). This feature brings Fossombronia very close to the
acrogynous Jungermanniales. In no case was an archegonium
seen arising directly from the apical cell; consequently its activities
are not checked by the production of sex organs.

326 BOTANICAL GAZETTE [APRIL

The first wall of the initial is transverse, and comes in above
the general level of the thallus, resulting in the formation of a
basal cell and an outer cell (figs. 22-24). The former may undergo
another transverse division immediately, or it may remain undivided
until the 3 vertical walls have appeared in the outer cell (fig. 26).
The presence of 2 transverse walls in the young archegonium caused
the writer, during the early part of the investigation, to suspect that.
possibly the first transverse division of the initial is followed by a
second one in the outer cell before the coming in of the 3 vertical
walls. Archegonia were seen, however, in which only one transverse
division of the initial had taken place (fig. 25), and the indications
were that the development of the archegonium may be typical, or
that the first 2 divisions of the archegonium initial may be the
same as the first 2 of the antheridium initial (fig. 10).

Before the appearance of the first vertical wall, archegonia
cannot be distinguished from antheridia, and after the first vertical
wall has appeared the mitotic figure which would settle this point
has disappeared. In several cases, however, the wall in the basal
cell had not become thickened. This fact, together with the
general aspect and behavior of the neighboring cells of the thallus,
the position of the first wall in the initial, and the elongated
character of the undivided stalk cell, convinced the writer, after a
study of all available stages in the preparations, that the second
transverse wall comes in the basal cell and not in the outer cell.

Subsequent development of the archegonium agrees with the
usual development of the archegonium of anacrogynous forms
(figs. 27-31). The cover cell divides by a median vertical wall
soon after its formation (fig. 29), and remains in this condition;
thus it does not contribute to the development of the neck, the
cells of which in all cases increase by intercalary divisions. The
mature archegonium has 6-8 neck canal cells, surrounded by 5
rows of neck cells (fig. 32). The venter is 2 cells in thickness,
and slender, and the neck but slightly twisted. The ventral
canal cell and egg are almost equal in size (fig. 31). After
the breaking down of the axial row the protoplast of the egg is
withdrawn somewhat from its wall, the very dense chromatin 1s
in close contact with the nucleolus, and elongated slender plastids

1920] | HAUPT—FOSSOMBRONIA 327

are conspicuous in the cytoplasm (fig. 33). The egg protoplast
does not lay down a new wall until after fertilization. More than
one archegonium in a group may function (fig. 45).

That the archegonium is of an advanced type is shown by its
early development from the initial, its relatively few neck canal
cells, its inactive cover cell, the intercalary growth of the neck,
and its slender venter.

SPOROPHYTE

The first division of the fertilized egg is invariably transverse,
and is followed by transverse divisions up to 5-7, the sequence of
which could not be determined (figs. 34-36). A vertical wall
then appears, intersecting the transverse walls (fig. 37), and
followed by another vertical wall at right angles to the first one,
so that 4 cells are seen in cross-section. Periclinal walls then
appear in the upper part of the embryo and a sterile wall is thereby
cut off from the central primary sporogenous cells. The relation
of the early divisions of the embryo to the formation of the foot,
seta, and capsule could not be determined, but it is certain that the
lower half of the fertilized egg contributes to the development of
the sporophyte, not merely forming an appendage to the foot.
A slender calyptra 3 or 4 cells in thickness is formed from the venter
of the archegonium (figs. 35, 38). A simple, bell-shaped involucre
develops after fertilization; it slightly exceeds the sporophyte in
length (fig. 45).

The sporogenous tissue is differentiated early in the history of
the sporophyte. In the formation of the spore mother cells and
elaters, the protoplasts of the sporogenous tissue withdraw from
their cell walls (fig. 39), those which are to form spores round out,
and both the spore mother cells and young elaters form a new
wall as the original walls of the sporogenous mass are dissolved
(fig. 40). The spore mother cells and young elaters are derived
from the sporogenous cells by the same number of cell divisions.
In F. cristula an elater is not homologous with a row of spore
mother cells, as in forms with a more highly specialized sporophyte,
but with a single spore mother cell. The spore mother cells
develop 4 inconspicuous lobes (fig. 42), the reduction divisions

7

328 BOTANICAL GAZETTE [APRIL

occur, and walls come in to separate the 4 members of the tetrad
(fig. 43).

The material available for the investigation yielded no stage
beyond that shown by fig. 44. No spiral thickenings were visible
on the wall of the elaters, and the spores were in various stages
of separation from their tetrads. The seta at this stage is not
yet elongated. Evans (3) has made a careful study of the mature
spores and elaters of this species. He says:

The elaters . . . . are remarkable not only on account of their small size
and delicate structure but also on account of their variability in form and
scanty development. Their most usual features, however, are found in the
local thickenings on their walls. Instead of forming 2 or more parallel spirals,
these usually consist of from 5 to 9 rings, some of which may be connected to
form a single rudimentary spiral... . . The elaters vary from 28 pw to 5op in
length and from 6» to 18 in width. The bands of thickening are less deeply
pigmented than in most species of Fossombronia and are sometimes very pale
indeed and difficult to demonstrate. ... . The brown spores in the type
material are mostly between 36 and 4op in diameter... . . The spherical
face is covered over with a more or less regular reticulum formed by inter-
secting lamellae about 2 in height... .. The meshes of the reticulum are
mostly 8-10 wide and the spherical face usually measures 6 or 7 meshes
across. Sometimes the reticulum is irregular or incomplete.

The mature capsule is globular or nearly so; its wall is in-
variably 2 cells thick and bears rudimentary annular and half-ring
fibers on the walls of the inner layer (fig. 46). There is no sterile
cap at the apex of the capsule. Dehiscence, according to CAVERS
(2), is by means of 4 valves in some species of Fossombronia, but
in most of them the upper part of the capsule breaks into plates
which are cast off irregularly.

Summary

1. The vegetative body of F. cristula consists of a minute,
creeping, rather profusely branched thallus which bears genuine
leaves in 2 dorsal rows, _

2. The apical cell is dolabrate. Branching is strictly apical.

3. The plants are monoecious, the sex organs occurring in the _
axes of the leaves. Antheridia and archegonia may occur in the
same leaf axis, and there is no time relation in the order of their

1920] . HAUPT—FOSSOMBRONIA 329

appearance. They originate from the immediate segments of the
apical cell, and their development is strictly acropetal.

4. The antheridia develop according to the usual method
found among the anacrogynous Jungermanniales. Variations
occur in the order of appearance of the walls in the primary stalk
cell.

5. Until the appearance of the first vertical wall, young apie
gonia cannot be distinguished from young antheridia. The
transverse division in the archegonium initial separates the ne
cell from the archegonium proper, and subsequent development
follows the usual Jungermanniales type. The cover cell is inactive,
6-8 neck canal cells are formed, and the venter is 2 cells thick be-
fore fertilization. “The archegonium i is of an advanced type.

6. The early divisions of the embryo are transverse, both
halves of the fertilized egg contributing to the development of
the foot, seta, and capsule. A calyptra 3-4 cells in thickness is
formed.

7. The sporogenous tissue is differentiated rather early in the
history of the sporophyte. The elaters are rudimentary, and
each is homologous with a single spore mother cell, not with a row
of them.

8. The sporophyte is primitive.

To Dr. W. J. G. LAanpD, under whose direction the study was
made, the writer makes grateful acknowledgment for his kind
advice and helpful criticism.

CARTHAGE COLLEGE

CARTHAGE, ILL.
LITERATURE CITED
1. Austin, Cor F., Characters of some new Hepaticae. Proc. Acad. Nat. Sci.

Philadelphia. p. 228. 1869.

2. Cavers, F., The interrelationships of the Bryophyta: Ill. Anacrogynous
Jitentiannriates. New Phytol. 9:197-234. 1910
3- Evans, A. W., Notes on New England Hepeticns, XII. Rhodora 17:107-

III. 1915.

4- Haupt, A. W., A morphological study of Pallavicinia Lyellii. Bor. Gaz.

66: 524-533. 191
& Miz. &. 7... zscostris crispula in the dune region of Indiana. Bryolo-

gist 19:67-68. x

330 BOTANICAL GAZETTE [APRIL

6. Humpnrey, H. B., The development of Fossombronia longiseta Aust. Ann.
Botany 20:83-108. 1906

7. LerrcEs, H., Untersuchungen iiber die Lebermoose, vol. 3, Die frondosen
Jungermannien. Leipzig. 1877

8. SCHIFFNER, V., Hepaticae in ENGLER and PrANTL’s Natiirlichen Pflanzen-
familien. 15: 38-61. 1909.

EXPLANATION. OF PLATES XVI-XIX

PLATE XVI
Fic. 2.—Thallus: a, side view; }, dorsal view.
Fic. 3.—Mitosis in apical cell; 1850.
Fic. 4.—Median longitudinal sextlond of apical cell; 660.
Fic. 5.—Median transverse section of same; 660.
Fic. 6.—Rhizoids; X85. :
Fic. 7.—Median longitudinal section of thallus through apical cell; 250.
Fic. 8.—Same as fig. 7: a, young antheridium; //, leaf; X68.
PLATE XVII
Fics. 9-20.—Stages in development of antheridium.
Fic. 9.—Antheridium initial; 790.
Fic. 10.—Young viene consisting of basal cell, stalk cell, and
primary antheridial cell;
Fic. 11.—Vertical divs of primary antheridial cell and later vertical
division of stalk cell;
Fic. 12. eae i transverse wall in stalk cell; 790
Fics. disk 14.—Formation of periclinal walls in primary antheridial cell;

Fr IG. 15.—Cross-section of same; X790.
Fics. 16-17.—Division of primary wall cells; 790.
Fic. 18.—Division of primary spermatogenous cells; 790.
Fics. 19-20.—Older stages; 660.
Fic. 21.—Archegonium initial and apical cell; 625.
Fic. 22.—First division of archegonium initial, apical cell, and mucilage
hair; 625.

Fics. 23-33.—Stages in development of archegonium.

1G. 23.—Archegonium initial; < 790.

PLATE XVIII

Fic. 24.—First division of same; X7
Fic. 25.—Formation of first vertical wall:

X790.
Fic. 26.—Appearance of second and third vertical walls and transverse
division of basal cell; 790.

PLATE XVI

BOTANICAL GAZETTE, LXIX

HAUPT on FOSSOMBRONIA

PLATE XVII

SOOM)

y
Ne maw

eS

aCe

BOTANICAL GAZETTE, LXIX

HAUPT on FOSSOMBRONIA

PLATE XVIII

Ad
ae )
ers ee

se: Saas
7 CV > ped
Fie Sh tessa >
eed (@) *: .
Tha LIX ty
oa ye ae Ay

BOTANICAL GAZETTE, LXIX

HAUPT on FOSSOMBRONIA

PLATE XIX

BOTANICAL GAZETTE, LXIX

Q. Ut I.

del.

HAUPT on FOSSOMBRONIA

1920] HAUPT—FOSSOMBRONIA 331

1G. 27.—Young AAS consisting of primary ventral cell, primary
neck canal cell, and cover cell; go.
Fics. 28-30.—Formation of ie canal cells, ventral cell undivided; X660.
Fic. 31.—Ventral canal cell and egg; X
Fic. 32.—Cross-section of ee of ee X60.
Fic. 33.—Mature archegonium; a5;
Fics. 34-37.—Development of ae S95.

PLATE XIX
Fic. 38.—Young sporophyte; 340.
Fic. 39.—Differentiation of spore mother cells and elaters; X 525.
Fic. 40.—Spore mother cells and elaters; 525.
Fic. 41.—Sketch of same stage; X50.
Fic. 42.—Lobed spore mother cells; x §25.
Fic. 43.—Spore tetrads; 525.
Fic. 44.—Nearly mature spores and elater; 525.
Fic. 45.—Sketch of same stage; X 50.
Fic. 46.—Wall of mature capsule showing thickenings on inner layer;

<

RESIDUAL EFFECTS OF CARBON DIOXIDE GAS ADDI-
TIONS TO SOIL ON ROOTS OF LACTUCA SATIVA’
H. A. NOYES AND J. H. WEGHORST
(WITH FIVE FIGURES)

Variations in the development of roots of plants, when carbon
dioxide gas is added subterraneously, have been described and
reported in a previous paper.?. The plants subjected to the carbon
dioxide gas treatments weré Capsicum annuum abreviatum, Lactuca
sativa, Raphanus sativus, and Phaseolus vulgaris. The last three spe-
cies were grown in the same soil, with fertilizer and manure treat-
ments in addition to the check treatment already reported upon.

The treatment of the soil in the pots subsequent to the removal
of the Phaseolus vulgaris plants in June 1917 was as follows. The
soil in each pot was emptied into a large pan, thoroughly mixed,
and returned to the pot. The water content was brought up to
optimum, and one seedling of Lycopersicum esculentum placed in
each pot. L. esculentum is considered a heavy potash feeder, and
the plants were grown without carbon dioxide gas treatments in an
endeavor to ascertain through plant growth the plant food made »
available by the previous gas treatments. The L. esculentum
plants were harvested in November (5 months later), and the pots
kept at near optimum moisture content until February 1, when
they were again set to Lactuca sativa. The object of this test was
to discover whether, on the addition of available nitrogen (in which
the soil was lacking), more mineral plant food, made available by
the carbon dioxide treatments of the previous spring, could be
utilized by the growing plants. The moisture content of the soil
in the pots was maintained at optimum by weighing and adding
distilled water. Available nitrogen in the form of ammonium
nitrate in quantities equivalent to 50 pounds of sodium nitrate per
2,000,000 pounds of soil was applied (with the distilled water added)

‘Contribution from Purdue University Agricultural Experiment Station, La
Fayette, Indiana.

2 Bor. GAz. 66:364. 1918.

Botanical Gazette, vol. 69] - [332

1920] NOYES & WEGHORST—ROOTS 333

on four dates, February 1, 9, 23, and March 27. The plants were
harvested April 15 and the roots removed April 20, 1918.

The roots of the plants grown in the pots that had received the
carbon dioxide gas applications the previous year had the mal-
formations attributed to carbon dioxide in the previous paper.
Where the soil had never been subjected to carbon dioxide treat-
ments, the roots were well spread and extended considerably into
the soil. Where carbon dioxide had. been applied, the roots were
shorter, spread out horizontally just beneath (0” to 2’’) the surface

F —Roots from mccpalegocie soil: left to right carbon dioxide treatments of
soil were o, rd and 24 hours per

of the soil, and had tap roots that were abnormally short, crooked,
and branching. The data with the fertilizer treatments are given
in table I. The results show that something was left in the soil,
due to carbon dioxide gas additions to the soil the previous year,
Which both shortened the tap roots and the distance below the
crown at which the roots curved or split up into smaller roots.
The residual effects of the gas were greater for the continuous than
the intermittent treatments. The roots of the plants where the
24-hour treatments of carbon dioxide has been given were more
affected under the manure than the fertilizer treatments.

BOTANICAL GAZETTE

ots from soil fertilized with 5 tons of manure: left to right carbon

Fic. 2.—
dioxide “eeloah of soil were o, 8, and 24 ‘eee per day.

Sa See,

3.—Roots from soil fertilized with single applicatis of complete fertilizer:

left to right carbon dioxide treatments of soil were 0, 8, and 24 hours per day.

NOYES & WEGHORST—ROOTS

—Roots from soil fertilized with ro tons of manure: left to right carbon

Fic
dincide | ects of soil were o, 8, and 24 hours per day.

Fic. 5.—Roots from soil fertilized with double application of complete fertilizer:
left to right carbon dioxide treatments of soil were o, 8, and 24 hours per day.

336 BOTANICAL GAZETTE [APRIL

The root of each set of three that had the best tap root was
photographed, and is shown in figs. 1-5. The left hand root in each
figure was grown in soil that did not receive carbon dioxide treat- -
ment; the middle one shows the residual effects of the 8 hours;
and the right hand one shows the effects of 24 hours of gas treat-
ments. With no gas treatment the roots of plants grown in manure
tend to resemble those in which carbon dioxide gas was applied to
the soil. This is confirmation of the statement made in the previous
paper, namely, that ‘“‘the results obtained in these experiments lead
to the belief that the carbon dioxide content of garden soils is some-

TABLE I

RESIDUAL EFFECTS OF CARBON DIOXIDE GAS ADDITIONS TO SOIL ON DEVELOPMENT OF TAP
roots oF Lactuca sativa

8 HOURS’ CARBON 24 HOURS’ CARBON
paar i DIOXIDE | pioxipe TREATMENT | DIOXIDE TREATMENT
TMENT pees an ©
PREVIOUS FERTILIZER FiG. NO.
TREATMENTS*
Distance to
Length Length {Distanceto! Length
(in inches) steuve (in inches) fit clive (in inches) Se iachell
ete SI a oe s.27 3.0T 34 ra 2.8 0.9 z
ns dry manuref. . .05 5.0 4:7 1.6 4.5 1.4 2
Complete fertilizer
pap acte Kapctotel gp 4.9 2.3 4.5 1.7 4.2 0.9 3
Te Liat ae 3.4 3-9 2.0 1.9 1.3 4
Complete a ex tilizer :
(double application)..| 4.0 1.7 3-2 1.9 3.0 0.9 5
PVETARE eos cs 4.7 act 4.9 t7 3.3 Eek jtete
be
* In addition nitrogen lied i i itrate on four dat ivalent to 50 pounds sodium
nitrate per 2,000,000 pounds soi
+ All figures are the veubase for three plants. ¢ Application per 2,000,000 pounds of soil.

§ Made from dried blood, dicalcium phosphate, and potassium chloride _meenne equal nitrogen, phos-
phorus, and potassium; nitrogen n equal to one-third that in the 5 ee of dry m

times detrimental to the root development of some of the plants
growing in the garden.”

These residual effects of carbon dioxide additions to soil obtained
over 9 months after the treatments were discontinued were un-
expected, as the soil had been removed from the pots and mixed,
and all water lost by evaporation added subterraneously. The
explanation is not easy. The data are reported as a contribution to
the knowledge of root growth, and it is hoped that it may help some
workers in explaining odd tropic phenomena or throw some light
on what is known as sisoil toxicity.”

MELLON ScHoot or INDUSTRIAL RESEARCH
- PirtsBurcGH, Pa.

‘LEAF-BASE PHYLLODES AMONG THE LILIACEAE!
_ AGNES ARBER
(WITH FOUR FIGURES)

In a recent paper (1) the writer advocated the view that leaves
of monocotyledons have no true laminae, but are either equivalent
to petioles +leaf-bases, or are still further reduced until they reach

€ point of representing leaf-bases alone. In ‘the paper cited,
attention was mainly concentrated upon petiolar phyllodes, but in
the present article it is proposed to review certain leaves among the
Liliaceae which seem to be of leaf-base or leaf-sheath nature, and
to consider the evidence upon which this interpretation is based.

There are a number of leaves among different tribes of the
Liliaceae whose external appearance and general structure may
well be taken to suggest a leaf-base origin. They show no differ-
entiation into sheath and limb; they are parallel veined and
furnished with a single series of normally orientated bundles. As
examples Hemerocallis, Tulipa, and Scilla may be cited. That a
view which presupposes a considerable power of development on
the part of the leaf-sheath is not necessarily too extreme, is indi-
cated by the fact that in some monocotyledons, in which there is
a differentiation into sheath and limb, the sheaths may attain
remarkable dimensions. For instance, the sheath of Typha may
be half a meter long (3). Again, Dommn’s (2) researches among
the Umbelliferae have revealed a case in which all the foliage
leaves are undoubtedly of: leaf-base nature, namely, Oreomyrrhis
linearis Hemsley. The linear leaves of this species, which bear a
general resemblance to those of monocotyledons, terminate in a
small rudiment apparently representing the blade. :

There is not, in fact, any a priori difficulty in the way of inter-
preting the leaves of Tulipa, etc., as leaf-base phyllodes. We may
now consider what positive evidence can be adduced in favor of

theory
r represents part of the work carried out during the tenure of a

‘This pape
Keddey Fletcher-Warr Studentship of the University of ean, and with the aid
of a grant from the Dixon Fund of the University of Lon

337] ae Gazette, vol. 69

338 BOTANICAL GAZETTE [APRIL

Ontogenetic evidence

Hemerocallis fulua L.—An apical bud of this plant was dissected
on Marchi. Neither in a leaf about 1 mm. long viewed under the
simple microscope, nor in younger leaves examined with the com-
pound microscope, could any distinction be discerned between the
“‘leaf-sheath”’ and the rest of the leaf. The leaf is open to the
extreme base, so that no closed sheath is formed.

Scilla hispanica Mill.—The young foliage leaves for the current
year were examined on March 1. All the leaves, down to the
youngest, were found to be similar structures, in which the hooding
of the apex was a relatively more conspicuous feature than in the
older leaves. In the mature leaf, the sheath is seen to be closed
for a very short distance at the base.

The conclusion to be drawn from the deeninéat of the leaves
of these two species seems to be that in the case of Hemerocallis
there is no evidence from the ontogeny of the existence in the leaf
of any region except the leaf-base or leaf-sheath; in Scilla the main
part of the leaf seems also to be of leaf-base nature, although the
apical region of the hooded tip may possibly bear another interpre-
tation, to which reference will be made later.

Evidence of comparative morphology

In order to test the interpretation here suggested, which explains
the leaves of Tulipa, etc., as essentially leaf-base members, 4
search was made for some dicetyedon possessing both leaves with
a well differentiated leaf-base, petiole, and lamina, and also reduced
leaves which could be closely compared with those of the mono-
cotyledons in question. Such a plant was found in Fatsia japonica
Decne., of the Araliaceae, often cultivated under the name of
Aralia. The normal foliage leaves of this plant are shown in
fig. 1A. There is a well marked sheathing leaf-base (0), a petiole
(p), and a palmate lamina. In addition, there are transitional leaf
forms with reduced blades, culminating in bladeless bud-scales
(fig. 1B). These are of the same nature as the leaf-base of the
normal leaf, although they are thinner in texture, and the parallel
veining is more obvious. The most interesting feature, however,
is that the apical region of the bud-scale, which is developed in

1920] ARBER—PHYLLODES 339

varying degrees, is solid and approximately cylindrical, and may
be interpreted as the rudiment of the leaf-stalk (fig. 1B, p). The -

Hi

HYACINTHUS

SCILLA TULIPA

FATSIA

S. —Fig. 1, Fatsia japonica Decne.: A, small normal foliage leaf;
b, leaf-base; p, petiole; B, bud-scale; 6, leaf-base; p, rudiment of petiole; C, trans-
verse section of apex of bud-scale at position marked with arrow in B; A and B, half
natural size; C, X23; fig. 2, Hyacinthus (garden var.): A, apex of leaf (half natural
size); B, transverse section through apex of leaf shown in A, at level of arrow; X23;
fig. 3, Scilla (garden var.): transverse section through apex of leaf which was flat and
dorsiventral except at tip; 14; fig. 4, Tulipa sylvestris: transverse section through
apex of leaf which was flat and dorsiventral except at tip; form on upper side shows
first indication of opening into main flat part of leaf; X23.

transverse section of this region shows a slightly dorsiventral ring
of bundles (fig. 1C), so that the anatomy is distinctly petiolar.
hen we turn to the monocotyledonous leaves which we wish
to interpret, we find that in certain of them there is an apical
Structure which closely parallels the petiole rudiment of the

340 BOTANICAL GAZETTE [APRIL

bud-scales of Fatsia. In the garden hyacinth, for instance, the leaves
may often be found to terminate in a short, solid, cylindrical apex
(fig. 24). On cutting sections of this apex, a ring of bundles is
revealed (fig. 2B), so that not only the external appearance of the
apex but also its anatomy corresponds to that of the Fatsia bud-
scales. Precisely the same thing has been found in another of the
Scilleae, a garden variety of Scilla; the transverse section of the
apex of this leaf is shown in fig. 3. In a, second subtribe of
the Lilioideae, the Tulipeae, a conspicuously developed, solid apex
may be observed, for instance, in the leaf of Tulipa sylvestris L.
Sections of this apical region again reveal a typically petiolar struc-
ture. Fig. 4 is drawn from a section at the base of the apical
region, and shows, in its form, the last traces of the influence of
the limb, but higher up this irregularity disappears, and the apex
becomes approximately cylindrical.

Such leaves as those of Hemerocallis, on the other hand, perhaps
may be compared with the countless dicotyledonous bud-scales in
which reduction has been carried still farther than in Fatsza, so
that they retain no vestige of any part of the leaf except the sheath-
ing base.

Summary

It is shown on evidence of ontogeny and comparative morphol-
ogy that certain leaves among the Liliaceae, such as those of Hemero-
callis and Scilla, are to be interpreted as equivalent to leaf-bases.
The lamina is entirely absent, and the petiole is either also absent
or is present in an extremely reduced form. The solid, approxi-
mately cylindrical apices in which the leaves of Hyacinthus, Tulipa,
etc., sometimes terminate, are held to represent the last rudi-
watitary phase of the vanishing petiole.

Batrour LABORATORY

CAMBRIDGE, ENGLAND

LITERATURE CITED
1. ARBER, AGNES, The phyllode theory of the monocotyledonous leaf, with
special reference to anatomical evidence. Ann. Botany 32:465-5°!- 1918.
. Dommy, K., Morphologische und phylogenetische Studien iiber die Familie
der Umbelliferen. Bull. Int. Acad. Sci. Prague 13:108-153. pls. I-3. 1908;
14:1-52. pls. 4, 5. figs. 10. 1
, Morphologische und biplosenetinchs Studien iiber die Stipular-
bildunets. Ann. Jard. Bot. Buitenzorg 24:117-326. pls. 23-33. 1911.

in

¥

DEVELOPMENT OF THE GEOGLOSSACEAE‘
G. H. Durr

Although a number of investigators have contributed develop-
mental studies on the Ascomycetes and very substantial progress
has been made, our knowledge of the ontogeny of the higher forms
of these fungi is still far from complete. In consequence, our
present systems of classification are full of gaps, and our concep-
tions of the affinities of these plants are often contradictory or
mere guesses. For the elaboration of a satisfactory system of
classification and for the consolidation of our ideas regarding
relationships, it is requisite that the ontogeny of a much larger
number of representative species be worked out. :

This investigation has been confined to the Geoglossaceae.
Observations have been made on practically complete stages of
Cudonia lutea, Spathularia velutipes, and Trichoglossum hirsutum,
and on some of the critical features of Leotia. Heretofore studies
in this family have been restricted to three species of the genera
Leotia and Mitrula.2 The chief interest centers around Cudonia
lutea and Spathularia velutipes because of the remarkable ascogonia
possessed by these plants, and because of the conspicuous veils
which render obvious to the naked eye their angiocarpous nature,
and which have long stood in, opposition to the distinction by which
SCHROETER’ separates the Helvellineae from the Pezizineae.

The youngest stage of Cudonia lutea which has come under
observation is in the form of a minute cushion of interwoven

threads measuring but 84 in height. At the center of this
loose assemblage of threads may be seen a small but definite group
of hyphae which are rendered conspicuous by their size and stain-
ing qualities. These are not ascogonia, as might at first be

* Preliminary communication.

* Dirrricu, G., Zur Entwickelungsgeschichte der Helvellineen. Cohn’s Beitrige
8:1. 1918.

Brown, W. H., The developement of the ascocarp of Leotia. Bot. Gaz.
59°443-459. IgIo.

3 ScHROETER, J., In ENGLER and Prantt, Die natiirlichen Pflanzenfamilien.
341] [Botanical Gazette, vol. 69

342 BOTANICAL GAZETTE [APRIL

supposed, but are the precursors of coiling procarps which arise
from them at a later stage, in a manner to be described. ;

So far as the writer is aware, such a sequence of structures has
not elsewhere been reported for any species of the Ascomycetes
proper. Among the lichens, however, a similar condition has
been recorded. In a paper dealing with the ontogeny of the
ascocarp of several forms of lichens, NrENBURG! figures and de- |
scribes bodies which are differentiated early in the process of
development, and which at a later stage give rise to “ carpogones.”’
These bodies are designated “‘generativen hyphen’”’ by this author.
Following his usage, the term “generative hyphae” will be employed
in reference to the threads here described and to their immediate
proliferations.

The next developmental stage exhibits a distinct differentiation
of vegetative tissues. There is now present a well organized outer
covering, which completely envelops the looser tissues, and at the
center the generative hyphae are more conspicuous than ever.
By this time the generative hyphae have proliferated to a slight
extent, and appear as a somewhat larger and more compact group
of threads with an extraordinary affinity for stains. As growth
proceeds the outer tissue expands, remaining in its peripheral
position as a true veil. Its persistence and growth are not functions
solely of the tissues that lie beneath it, but of itself as well. By
its own growth it is able to keep pace for a considerable time with
the rapid enlargement of the cap, a fact that is true even of that
portion which is eventually separated from its connections by the
developing hymenium. This growth, in contrast with mere
stretching, results in a marked increase in the thickness of the
veil, measurements showing that the earliest envelopes average
about 20 , while at maturity they approach 7o u in thickness. The
veil ruptures over the hymenium only, and there only after the
latter is well matured.

By upward growth and by the appearance of a mass of what
may be termed parenchymatous tissue at the base of the young
fruit, the generative hyphae are forced to assume a subapical

4 NIENBURG, W., Beitriige zur Entwickelungsgeschichte einiger Flechtenapothe-
cien. Flora 98: 1907-1908.

1920] DUFF—GEOGLOSSACEAE 343

position. This position is retained until they give rise to the
-procarps. At this time the height of the fruit body is about 2 mm.,
and the cap has been well differentiated from the stem. At such
a stage the generative hyphae largely fill the upper portions of the
cap, and the procarps arise as branches from these hyphae. The
procarps are numerous, coiling, and deeply staining structures,
scattered irregularly throughout the cap. These coils are con-
tinued upward by what appear to be “‘typical’’ multiseptate
trichogynes, which penetrate the envelope, projecting into the air
fora short distance. Spermogonia and spermatia are entirely lack-

ing, and it is not thought that the trichogynes are functional organs.
_ Despite the great difficulty of staining differentially both the
generative hyphae and the procarps, owing to the remarkable
affinity for stains exhibited by these structures, there is sufficient
evidence to show that the cells of the procarp, including those of
the trichogyne, are originally uninucleate. Later the ascogonial
cells become multinucleate, the nuclei being small and paired;
and ascogenous hyphae arise from them into which these ee
probably pass.

It is important to note that up to this time there has ee no
sign of a hymenium. The fruiting surface now makes its first
appearance in the form of paraphyses immediately beneath the veil.
Before the paraphyses have attained their full development the
ascogenous hyphae, that meanwhile have taken their origin from
the procarps in close proximity, and have rapidly proliferated and
gone through various evolutions of hook formation, begin to organ-
ize asci. This young hymenium is inclosed by the veil, and
remains so until many of the asci are mature and spore discharge
is ready to commence. The nuclear phenomena preceding spore
formation are typical in their chief features.

The developmental history of Spathularia velutipes follows a
course not unlike that of Cudonia lutea. The youngest fruits of
this species that have been examined are somewhat larger than the
youngest species of Cudonia, being in the neighborhood of 0.5 mm.
in height. At this stage the young Spathularia is covered with an
envelope, but the inner tissues are quite undifferentiated, and there
are as yet no signs of any structures resembling the generative

344 BOTANICAL GAZETTE [APRIL .

hyphae of Cudonia. In the next stage of the series, however,
threads resembling generative hyphae are visible, and they have
already taken up their position just behind the apex of the some-
what cone-shaped ascocarp. The envelope here is worthy of some
remark, inasmuch as it is easily differentiable by staining into two
parts, an outer and aninner. The inner tissue is capable of growth
and is responsible for the-persistence of the veil in Spathularia,
and for the continued production of the outer tissue which becomes
split by the growth of the fruit body into adhering masses of cells
which are responsible for the velvety appearance from which the
species derives its name. Measurements of the thickness of the
envelope in the youngest and in mature specimens here also indicate
the extent of this growth, and show the veil to be capable of doubling
in thickness, increasing from about 25 to soy. This is but a
rough and inadequate index, however, since the outer tissue may
be considerably worn away.

Procarps of a very much reduced nature are produced in
Spathularia velutipes. These appear even later than those of
Cudonia, arising after the formation of paraphyses. They are
more variable in size and shape, and do not possess trichogynes.
They are responsible for the initiation of the paired condition of
the nuclei, and ascogenous hyphae may be seen arising from them.
The entire ascogonial system in Spathularia is just as refractory
with respect to stains as that of Cudonia, and nuclear details,
consequently, are very difficult to obtain. In all other respects
Cudonia and Spathularia resemble one another closely.

Examination of a complete series from a very young stage to
maturity has shown that Trichoglossum hirsutum is not possessed
of a veil at any time in the history of the development of its fruit
body. The long setae that characterize the ascocarp of this
species, however, are present from the very first. This condition
is noteworthy, inasmuch as it is very similar to that which F1tz-
PATRICKS has described for Rhizina undulata. In these two species
we have the only members of the Helvellineae whose develop-
mental history has as yet been described, for which the presence

s Fitzpatrick, H. M., The development of the ascocarp of Rhizina undulata Fr.
Bot. Gaz. 63:282~-296. 1917.

1920] DUFF—GEOGLOSSACEAE 345

of a veil at some stage of their development has not been claimed,
and each is provided with these remarkable setae. In matters of
sexuality Trichoglossum appears to be still more reduced than
Spathularia. Ascogenous hyphae arise from threads which are
little if at all differentiated from the vegetative hyphae.

Although Dirrricn (Joc. cit.) claims for Leotia lubrica the
possession of a veil in its younger stages, BROwN (loc. cit.), in his
more recent paper on this species, makes no mention of the occur-
rence of any such structure, and apparently has observed none.
A tissue overlying the hymenium has been observed by the writer
in a fairly well advanced specimen during the course of a cursory
examination of this form. Younger stages which show this
covering have not been found, however, so that considerable
uncertainty obtains with regard to the identity of this tissue with
that figured by Dirrricu.

A point of very great interest in this investigation is the close
resemblance of the conditions described for these Geoglossaceae
to those which NrENBURG attributes to the Cladonia-like lichens
Icmadophila, Sphyridium, and Baeomyces. The occurrence in these
lichens of generative hyphae which later give rise to carpogonia has
already been mentioned. These carpogonia are “typical” coils
with trichogynes in Icmadophila; but they are progressively more
degenerate in Sphyridium and Baeomyces, in the last of whic
NIENBURG was unable to distinguish their presence with certainty.
Further points of similarity include the occurrence of an envelope
in the early stages, and the methods of ascus formation. This
remarkable parallelism evidently represents a relationship. Al-
though a general relationship between the Ascolichens and other
ascomycete groups, such as the Discomycetes and Pyrenomycetes,
has long been recognized, and although some lichenologists have
advocated and attempted the distribution of the lichen genera
among those of other Ascomycetes, a fundamental basis of relation-
ship between the discolichens and the order Helvellineae has been
wanting. This basis is supplied here and consists of a close
similarity in developmental history, particularly with regard to
the veil and to the manner and time of appearance, number,
Position, and condition of procarps. As our knowledge of these

346 BOTANICAL GAZETTE [APRIL

forms increases, the extent of this relationship will ace: loach
be more clearly shown.

A detailed illustrated account of this work is to be published in
the near future.

The writer desires to acknowledge his indebtedness to Pro-
fessor J. H. FAautt, of the University of Toronto, under whose
guidance this investigation has been prosecuted, and to express
his thanks for valued direction and criticism.

UNIVERSITY oF ToRONTO
CANADA

BRIEFER ARTICLES

THE CINCHONA STATION

The lease of the Cinchona Station by the Smithsonian Institution on
behalf of a group of contributing American botanists was interrupted by
conditions existing during the war. It has now been resumed, and the
laboratory will be available for American botanists during the coming
year.

This tropical ice in a well kept botanical garden containing
many exotic trees, shrubs, vines, and herbaceous perennials from all
quarters of the earth, is located at 5000 ft. elevation, on the southern
slope of the rugged Blue Mountains of Jamaica, within half an hour’s
walk of an undisturbed montane rain forest.

The dry ridges and sunny valleys of the south side of the Blue
Mountains offer many types of peculiar ferns, epiphytic bromeliads,
grasses, mistletoes, and lianes. In the rain forest of the north side are
to be found many species of liverworts, mosses, and ferns, the latter
ranging from the very diminutive epiphytic species of Polypodium, only
an inch or two in height, to the scrambling species of Pteridiwm, Gleic.
or climbing Lomaria of many yards in length, and the great tree fecd,
40 ft.in height. There are also many interesting native species of trees,
shrubs, and ‘vines which together make parts of the forest a practically
impenetrable jungle. There are great stretches of the northern slopes
of the Blue Mountains, within a day’s walk of Cinchona, that have
never been explored by the botanist, not even by the collector.

Botanists wishing to study plants of the lowlands or of the sea
Coast can make their headquarters in Kingston, and such workers have
always had the use of the library, herbarium, and laboratory at Hope
Gardens. These gardens also contain a fine collection of native and
introduced tropical plants, offering much material for morphological
and histological study. Cacti, agaves, and other xerophytic plants of
the seacoast, and the algae of the coral reefs along the shore, afford still
Other types of vegetation of great ecological, developmental, and cyto-
logical interest. Castleton Garden, the third botanical garden of the
island, has a very different climate from either Cinchona or Hope, for it
is located in a hot steaming valley, 20 miles north of Kingston, where
347] [Botanical Gazette, vol. 96

348 BOTANICAL GAZETTE [APRIL

cycads, screw pines, palms, orchids, figs, ebonies, the gorgeous Amherstia,
and many other tropical trees grow luxuriantly.

All in all, Jamaica probably offers the botanist as great a variety of
tropical conditions within a day’s walk of Cinchona and a day’s drive
from Kingston as can be found anywhere in an area of this size. It is
evident that the opportunities for the study of many kinds of botanical
problems are abundant at Cinchona, Hope, and Castleton. In fact,
there are many botanical problems of prime importance which can be
studied only in such environments."

Any American botanist wishing to work at Cinchona may be granted
this privilege by the Cinchona committee, consisting of N. L. BRritTon,
J. M. Coutrer, and D: S. Jounson. Inquiries for this privilege and
for information regarding the conditions under which it may be granted
should be sent to the writer.—D. S. Jounson, Johns Hopkins Univer-
sity, Baltimore, Md.

CHROMOSOME NUMBER IN THE SEQUOIAS

For some years we have been concerned with cytological studies
in the genus Sequoia. In particular a review of the evidence presented
by Lawson? on the life history of S. sempervirens has been attempted.
That interest attaches to this genus is obvious, and certainly
the information available in regard to the life history of S. gigantea is
meager. The present note is intended primarily to call attention to
certain points which have been indicated in our preliminary studies.

Lawson reports that, in his material collected at Stanford Uni-
versity, California, the pollen grains are formed during the second or
third week of December, and that the pollen is shed during the first
week of January. In our experience, extending over some three years,
the pollen is often mature in September and rarely is it found on the
tree after November. Our observations have been made on trees of
the same size growing in three different loc4lities: Berkeley, Redwood
Peak, and Mill Valley, California. There is great variation in the
time of pollen shedding. Two trees standing side by side may show
a difference of two weeks to a month in the occurrence of this phenome-

*For further details see Science 43:917. 1916, and Popular Science Monthly,
January, 1915.

2 Lawson, A. A., The age icntan Ede fertilization, and embryo of
Sequoia sempervirens. Ann. Botany 18:1-28.

3 Suaw, W.R., Cidetiieihiai’ to the life ae of Sequoia sempervirens. Bot.
GAZ. 21:332-339. 1896.

1920] BRIEFER ARTICLES 349

non, and in any two consecutive seasons an individual tree may shed
pollen on dates separated by a corresponding interval of time. In the
same way it has been found impossible to predict with any degree of
accuracy the time of occurrence of any of the significant stages in matura-
tion, and this fact has rendered more difficult the determination of
chromosome number in S. sempervirens. Numerous efforts so far
have failed to discover the reduction divisions in the microspore mother
cells

As to chromosome number in S. sempervirens, LAwson remarks
that ‘‘as near as could be estimated, there are 16 chromosomes in the
gametophyte and 32 in the sporophyte.”’ In recent tabulations of
chromosome numbers in plant species, 45 gymnosperms are listed.
All but 12 of these have x 12, and 2x 24, and of these 12 (x 16 and 2x 32)
a number are listed as doubtful. On this basis perhaps there might
be legitimate ground to question LAwson’s count. In sections of
root tips of S. sempervirens we have made counts which only in rare
instances confirm Lawson’s report. The difficulties are great in such
material, however. In corresponding and more favorable material of

|S. gigantea, we have uniformly counted from 21 to 24 chromosomes,
but never a greater number.

With these facts in mind, the following possibilities present them-
selves. First, if LAwson’s count is correct for S. sempervirens and if
our count is correct for S. gigantea, the two species have different chromo-
some numbers. Second, if our suspicion of Lawson’s count in S. semper-
virens is valid and if our count in S. gigantea is correct, both species
have x 12 and 2x 24. The third possibility involves an inaccuracy in
our count of S. gigantea and chromosome numbers 16 and 32 for both
species. In our opinion the second possibility is the only one which
merits serious consideration. It seems worth while, however, to present
the whole situation, since the other possibilities cannot wholly be left
out of account with the data at hand. Further studies will involve

- an investigation of the life history of S. gigantea and the obtaining of
a final conclusion as to chromosome number in S. sempervirens.—T.
Goopspeep and M. P. Crane, University of California.

CURRENT LITERATURE

BOOK REVIEWS
Ecology of tide lands

There is no place more suitable for the study of dynamic ecology than in
areas swept over by the tides, and there is no one better able to write on the
problems of such areas than Professor OtIvER.t. For years he and his stu-
dents have attacked seashore problems, first on the coast of Brittany, and
more recently on the coast of Norfolk. The Bouche d’Erquy and. Blakeney
are household words to all students of shore ecology. The main results of
OLIvER’s studies are now incorporated in book form, and, quite in the spirit of
the time, he has become associated with an engineer, who presents the practical
application of ecological principles to engineering problems along shore; the
result is a masterpiece of applied ecology.

The first chapters deal with tide and current data, the tidal compart-
ments of rivers, and the foreshore. That the problem is one of no mean
importance is shown by the fact that in the British Isles there are 8000 miles
of shore line and 11,000 miles of river front at high water; and there are
1250 square miles of area between tides. OLIvER’s greatest contribution is
in chapters iv-vii, which deal with the function of vegetation, sand dunes
and their fixation, and shingle beaches and their fixation. The fundamental
importance of plants in the stabilization of shore lines has been inadequately
realized by engineers, although sporadic and often ineffectual planting of sand
dunes has been more or less indulged in for a century. A perusal of this work
makes it clear that ecology must form a large part of the education of an
engineer who really wishes to get at the foundations of shore problems. So
far as dunes are concerned, Britain’s problem is not as great as that of Gascony
and other continental tracts. The most satisfactory plant for dune fixation
is Psamma (Ammophila), although Elymus arenarius, Carex arenaria, and
other species may also be used, Even lichens and mosses have a fixative
value. The chief factor in dune fixation lies in the development of an effec-
tive nacegar ve

of the striking features of British shores is the shingle beach, where
sods are piled up by vigorous wave movement. At Dungeness the
shingle covers 10,000 acres. At Blakeney on the Norfolk coast the shingle is
piled up to a height of 10 feet above high water, and at Chesil on the Atlantic
shore, the height is 30 feet. Shingle is kept mobile (1) by wave impact and

E., ain Ottver, F. W., Tidal lands; a study of shore problems.

AREY, A.
8vo. pp. 284. pls. 29. figs. 54. London: Blackie & Son. 1918.
a

)

. 1920] CURRENT LITERATURE 351

throw, resulting in a talus or fan on the lee side, (2) by percolation, especiall
where there is large tidal difference, or (3) by stream scour on the lee side.
Suaeda fruticosa is able to colonize upward growing shingle, quite as Psamma
may colonize an upward growing dune; Swaeda is an especially good pioneer,
because of its halophytic proclivities. Later stages, as shingle growt
decreases, are characterized by mat plants such as Silene maritima and Con-.
volvulus Soldanella. A plant-of the latter increased i in area within four years
from 9 to 525 square feet.

An interesting chapter deals with the reclamation of salt marshes. It
is OLIVER’s view that a marsh would not fill alone by silting, by reason of alter-
nate filling and cutting. Reclamation may be brought about naturally by
coastal elevation or by the building up of a barrier dune, or it may be brought
about by artificial agencies. A remarkably effective plant reclaimer of halo-

phytic shores is Spartina Townsendii, a supposed natural hybrid of S. stricta.

and S. alterniflora. This species was first noted at Southampton in 1870, and
now covers thousands of acres. In 1895 it appeared at Bayonne, on the
Bay of Biscay. It is interesting to note that these two areas are the
only ones known where the areas of the supposed parent species overlap.
—H. C. Cowes

NOTES FUR STUDENTS

Root systems.—Since the notable work of CANNON in 1911 on the roots of
desert plants, nothing has contributed so much to our knowledge of ‘subter-
ranean plant organs as the recent publication by WEAVER? in which he has
described the root systems of some 140 species of shrubs and herbs from the
prairies of Nebraska and Washington, the plains and sand hills of Colorado,
and some gravel slide and forest communities of the Rocky Mountains of
Colorado. For each of the habitats under investigation many data regarding

gs and
graphs of excavated root systems are among the most valuable ite of the
report
he the Nebraska prairie there is a striking individuality in the root sys-

species. The deeper rooted species comprise 55 per cent of the 33 species
examined, and extend beyond a depth of 5 feet, some reaching as much as
20 feet below the surface, many of them having few or no absorbing roots in
the first few feet of soil. The majority of the deeply rooted species are dicoty-
ledons; but it is notable that the group also includes three dominant grasses,
Poniciin virgatum, Andropogon furcatus, and Agropyron repens. In contrast

? Weaver, J. E., The ecological relations of roots. Carnegie Inst. Wash. Publ.
286. pp. vii+228. pis. 33. figs. 58. 1919

352 BOTANICAL GAZETTE [APRIL

with this group, all plants with roots confined to the upper 2 feet of the soil
are grasses, and include such species as Koeleria cristata, Stipa spartea, Elymus
canadensis, and Distichlis spicata.
Such root systems are to be related to the deep, mellow, loess soil with high
water-holding capacity and moist subsoil. Here the data of WEAVER cor-
-respond well with those of Atway3 for moisture conditions, although the

latter. In the upper 4 or 5 feet there is usually at midsummer a reduction of
the water supply to a point below the wilting coefficient, these data cor-
responding with those of the reviewer for the grasslands of the Chicago region.‘
The climatic conditions of the prairies of southeastern Washington are
shown to be more severe than those of Nebraska, not only because of a smaller
annual precipitation, but also because only one-third of this rainfall comes
during the growing season. As a part of the response, the early flowering
grasses predominate, and many of these, such as Koeleria cristata, Poa Sand-
re and Festuca ovina have their roots confined to the upper 18 inches of
here remain, — some grasses and many dicotyledons that are
decidedly deep roote
ata also.are given for a “chaparral”? community transitional from
the prairie to the forest, and dominated by species of Symphoricarpos, Rhus,
Corylus, and Rosa. The designation is unfortunate, for the best usage would
limit the term “chaparral” to an evergreen scrub like that occurring on the
Pacific Coast of California.

n comparison with the root systems of the prairies, those of the plains are
characterized by a larger percentage of moderately deep rooted species, fewer
very deeply rooted plants, and by a more extensive system of surface absorb-
ing and wide spreading laterals. SHANtTz5 reported that at Akron, Colorado,
almost the entire root system of all the grasses is limited to the 18 surface
inches. The conditions are evidently different near Colorado Springs, for
there WEAVER reports one grass only, Koeleria cristata, with roots confined
to the surface 2 feet. Grouping into layers is again evident; the most dis-
tinctive feature of the plains species, in addition to spreading laterals, is the

erate penetration of the deep rooted species. This is doubtless due, as
indicated by both WEAVER and Atway (loc. cit.), to the comparative impene-
trability of the eeey dry subsoil.

The sand hill community exhibits in a still more striking manner the
development of a profusion of widely spreading laterals in the upper 2 OF

Sore F. J., et al., Relation of minimum moisture content of subsoil of
prairies to hygroscopic coefficient. Bor. Gaz. 67:185-207. I919.

4 Bor. Gaz. 58:193-234. 1914.

5 SHantz, H. L., Natural vegetation as an indicator of the capabilities of land for
crop production in the great plains ins area. U.S. Dept. Agric., Bur. Pl. Ind. Bull. 201-
Pp. too. pls. 6. figs. 23. 1911.

1920] CURRENT LITERATURE 353

3 feet of soil. This is true even of the deep rooted species, and is doubtless
to be related to distribution of soil moisture. It is notable that MAarKtr®

a considerable variety of systems, and tein rather definite layers of penetra-
tion lessening competition for the scarcé water supply.

n the succession from the gravel slide with coarse soil to the forest rich in
humus, the Colorado Rocky Mountains afford an interesting series. WEAVER

trolling factor in each case. The intermediate half gravel slide, with its sur-
face more than half occupied with plants, curiously ona has more deeply
rooted plants than the associations preceding or succeeding
A comparison of species occurring in two or more ports habitats shows
that of 10 species examined, 7 exhibit changes in root habit in response to the
changed environment, while 3 remain quite constant. Such studies of the
response of root systems to environment have attracted the attention of other
workers. WATERMAN’ finds roots developing under dune conditions some-
what responsive to organic remains in the sand, al usually adhering
rigidly to their specific inherited form. Such rigidity was found by Putiinc*®
in the shallow root systems of Picea mariana, Larix laricina, and Betula alba
papyrifera, as well as in the more deeply rooted Pinus Strobus and P. Banksiana;
while both the shallow rooted Picea canadensis and the deep rooted Populus
reaerntete exhibited considerable plasticity.
Cannon? believes that the roots of deeper penetration are less responsive
to changes ri aeration and temperature than those of more superficial habit,
ing his conclusion upon the study of Pistacia atlantica and Prosopis

latter class. The individuality of such responses is further shown by the
studies of CANNON and FREE,” proving that while certain plants like Opuntia
stop root growth with a soil atmosphere of 50 to 75 per cent carbon dioxide,
others, like Prosopis, continue growth as long as 2 per cent of oxygen is

® MarKkLE, M. S., Root systems of certain desert plants. Bor. Gaz. 64:177-205.
Sigs. 33. 1917.

7 WaTERMAN, W. G., ee of root systems under dune conditions.
Bor. neg outa figs. 17.
, H. E., Root ee and lant distribution in the far north. Plant
Witd as: aa. en z. 1918.
9 Cannon, W. A., hye aR ag root habits by sate means. Carnegie
Inst. Wash. Yearbook 17:83-85. 1
7 Cannon, W. A., and FReEE, A ye The ecological significance of soil aeration.
Science N.S. 45:178-180. 1917.

ee

354 : BOTANICAL GAZETTE [APRIL

present. They also showed that while the roots of Coleus blumei and Helio-
tropium peruvianum show injury in 3 days by an addition of 25 per cent
nitrogen to the soil atmosphere, Neriwm oleander is unharmed by 50 per cent
of nitrogen, and the roots of Salix (nigra?) grow freely in pure nitrogen. Simi-
lar results were obtained by the use of helium instead of nitrogen as a di-
luting gas.

More recently BERGMAN" has found similar differences of response in the
roots of land and swamp plants, the dead roots in the former often being
replaced by others near the surface of the water, showing lack of aeration to be
one of the most important factors involved. Several experiments serve.to give
emphasis to this fact. He found that land plants with submerged roots soon
show pronounced wilting, the wilting being less marked when the submergence
is in aerated water, and a reduction in transpiration preceding wilting. This
is taken to-indicate that absorption is reduced below the amount demanded
by transpiration. When aeration is provided, the use of swamp water for
submergence or watering gives no other harmful results than those obtained
by the use of tap water or nutrient solutions. The oxygen content of swamp
water in nature was found to be large in the open lakes examined, but to show
decided decrease through the Carex stages to the Chamaedaphne-Andromeda
and Larix-Picea stages. This leads to the conclusion that the mingling of
hydrophytes, mesophtyes, and xerophytes in swamps is due to local differ-
ences in habitat, such as water level and aeration, affecting the rate of absorp-
tion and its ratio to transpiration; hence ecesis in swamps can occur only
when the oxygen requirements of the species are satisfied.

These citations show that considerable descriptive matter has added
materially to our knowledge of root systems, and that the few physiological
investigations of these organs have pointed to wide diversity in the responses
of individual species to changes in their environment.—GeEo. D. FULLER.

Alpine singers of the central Andes.—HAuMAN™ has recently described
t 31 and 37° south latitude,
t m. This region possesses many pea
above 6000 m. aia the highest snd best known being Aconcagua, with an
altitude of 7020 m. These mountains are snowcapped and possess 4 good
development of glaciers, from which flow tortuous and variable streams,
fu almost the entire water supply for the sparse reenien since the
growing season in these mountains is almost entirely without r
temperature records are imperfect, but an important factor is the Hight ‘frosts,

a — alpin fot

**Beroman, H. F., The relation of aeration to the growth and activity of roots
and its influence on the ecesis of plants in s wamps. Ann. Botany 34:13-33- fig. 3:
1920,

2 HAuMAN, Lucten, La végétation des haut 3ildere de Mendoza (République
Argentine). Anales Soc. Cien. Argentina 86:121-188. pls. 5-22. figs. 7. 1918.

1920] CURRENT LITERATURE ga

which are common throughout the growing season. One station at 2700 m.
gives an annual mean temperature 6.5, with a mean maximum of 13.4 and a
ean minimum of 0.1°C. Humidity at all times is low, while wind velocity
is decidedly high and constant. Precipitation as recorded at 2000 m. seems
to be irregular and variable, the annual amounts ranging from 20 to 68 cm.,
occurring principally in the colder months in the form of snow. This deficiency
of rainfall, combined with other factors, makes the vegetation not only very
scanty, but limited to valleys and slopes which possess streams or seepage
water from the glaciers and snowfields. In the absence of mountain lakes
aquatic vegetation is scanty, and anything resembling mountain meadows is
limited to the stream edges and small alluvial fans. Such grassy associations
appear to resemble closely similar alpine areas elsewhere. Related to the
alpine meadows are the “high Aigeaaa oases,” rae at 3200 to 3900: m. "
where at the foot of talus or morainal slopes some alluvia 1 soil has
These oases vary in size, but rarely reach 100 m. in diameter. They are often
dominated by the juncaceous Andesia bisexualis 15 to 30 cm. high, forming a
thick carpet.
Trees are absent throughout, and even in the valleys the shrubs do not
exceed 2m. in height. ee Aa ee hs legume) is the most plentiful

shrub; while among the others ar mericana andina, Berberis empetri-
folia, and Senecio uspallatensis. p se “oni the only cactus of the
region, together with Azorella Gilliesii and Laretia acaulis, two umbellifers,

orm a curious trio of herbaceous —— plants confined to ihe eVOneye:.
Upon the more exposed parts of t
of prostrate, tufted, rosette, and cushion plants, often with a striking oe
ment of large woody roots. These growth forms are accounted for as being
a response to exposure to high winds and dependence upon a subterranean
water supply. Upon the slopes Adesmia trijuga, with shrubby cushions
30cm. high, together with Poa chilensis and Stipa speciosa in tufts, dominate
the area, forming scattered dots over the rocky landscape. Most abundant
upon the summits between 3000 and 4000 m. are the subterranean woody
cushions of Adesmia subterranea, whose leaves form a carpet upon the surface.
Accompanying this species with similar growth forms are the more uncommon
Verbena uniflora and Oxalis bryoides.
The entire vascular flora consists of 417 species, including one pteridophyte,
atone fragilis, and one gymnosperm, Ephedra. Among the richest
milies are Compositae with 85 species, Leguminosae with 36, Gramineae
ox 34, Cruciferae with 28, Portulacaceae with 15, Umbelliferae with 15,
Rosaceae with 12, Cyperaceae with 12, Oxalidaceae with 10, and Violaceae
and Caryophyllaceae with 9 species each. Large genera are Senecio with
26 species, Adesmia with 16, Calandrinia with 15, Astragalus with 12, Oxalis
with 10, and Viola with 9 species. The scarcity of the Saxifragaceae, be
two rare species, and the entire absence of the Ericaceae and Primulacea
worthy of note. Lichens, abundant at the lower altitudes, become ver rare

~

356 BOTANICAL GAZETTE [APRIL

above 2800 m.; mosses are common about springs up to 3600 m., but liver-
worts are sxihizioby lacking. More than one-half the species (210) are classed
as belonging to the central Andes, 60 being endemic. There are no endemic
genera, but notable among this group are such aggregates as 6 species of
Adesmia, 2 of Boopis, 12 of Senecio, and 2 new varieties of Koeleria. The
other elements are the northern tropical with 16 species, the subtropical with
21 species, the basal Argentinian with 56 species, the southern Andean with
10 species, the Patagonian with 73 species, and the cosmopolitan and intro-
duced species numbering respectively 28 and 17. This introduced element
must be regarded as small when it is recalled that the Mendoza River valley
has been the trans-Andean route for centuries.

Photographs and careful drawings of many of the interesting forms add _
much to the value of the report.—Gro. D. FULLER.

Crop centers.—A great service in unifying ecology and agriculture has
recently been rendered by WALLER,® who has illustrated by well chosen
examples the close relation that exists between crop and vegetation centers.
TRANSEAU has shown how closely vegetation centers are indicated by a map
showing the ratio of rainfall to evaporation, and WALLER now emphasizes the
fact that corn, wheat, and similar crops show strikingly similar relations. It
is often said that crops are moving west or north, which merely means for
the most part that we are finding their range. For example, wheat was
first cultivated away from its proper center, so that in the last 70 years the
center of wheat cultivation has moved 7oo miles west and 100 miles north.
A fundamental difference between crops and native plants is that when the
latter extend far beyond their range, it is chiefly in the poorest soil, since
competition with plants proper to the district exclude them elsewhere. Crops
grown at the edge of their range, however, must be grown in the best condi-
tions available, and of course are exempt from competition. Special atten-
tion is paid to corn, wheat, and cotton, and the maps showing their distribu-
tion are very significant. Of course there are many complexities in working
out the thesis. Economic considerations, such as problems of market and

North Dakota in the production of spring wheat, are rig to edaphic fac-
tors; in each case there is rich prairie soil—H. C. CowLE
Increasing catalase activity in yeast cells —EuLEr and Bi1x" have deter-
mined the effect of various conditions and reagents upon the catalase activity
3 WALLER, A. E., eis centers of the United States. Jour. Amer. Soc. Agron.
10:49-83. figs. 8. 1918
E

ULER, H. V., sa Bux, R., Verstirkung der Katalasewirkung in Hefezellen.
Hoppe-Seyler Zeit. Physiol, Chem. 105:83-114. 1919.

1920] CURRENT LITERATURE h >

of yeast cells. When possible they used the potassium permanganate titra-
tion method for determining catalase activity. In cases where additions of
thymol, glucose, etc., rendered the permanganate method inaccurate, the
volumetric method was used. They used mainly their cultures of distillery
top yeast S.B. II. Some experiments were run with brewery bottom yeast.
They agree with PHRAGMEN’s findings that yeast splits dilute solutions of
hydrogen peroxide without secreting a soluble enzyme into the bathing fluid.
The reaction is one of the first order. The reaction constant increases in
proportion to the amount of yeast. Small amounts of protoplasmic poisons
(toluol or chloroform) raise the catalase activity of these cells 6-fold. When
cells were dried in the air or otherwise without injuring them, the catalase
activity rose 10-15-fold. When emulsions of the yeast were heated o. 5-2
hours at 55-63° C., the catalase activity rose 20-30-fold. The activation by
heating i is greatly influenced by reagents in the emulsion at the time of heat- -
ing. Similar activation of catalase has been demonstrated in a number of
other micro-organisms. The catalase activity of yeast can be raised by
previous treatment with sugar solutions. This increased catalase activity is
not due to increased permeability of the cells to catalase, but is an activation
within the living cells. The reaction constant is not a measure for the catalase
content of the cells—W. CRrocKER. :

Parasitism.—HAwkins and Harvey* have made an interesting study of
the nature of the resistance of White McCormick tubers to the tuber rot
caused by Pythium debarya num Hesse. The White McCormick is very

susceptible. From their experiments they think it probable that the fungus
enters the cells of the potato by mechanical puncture of the cell walls and not
by enzyme action. The McCormick is less susceptible to the disease than
the other varieties, because its cell walls are more resistant to this mechanical
puncture. Determinations of the pressure required to puncture the cell
walls give much higher results for the McCormick than for the susceptible
varieties. The rate of growth of the fungus is much slower in the McCormick.
Correlated with the greater resistance of the McCormick is a higher crude
fiber content. If its osmotic pressure is to be considered the force available
o the fungus for this mechanical puncture of the cell walls, then the cases of
resistance of the potatoes used in the experiments would be explained, with
three exceptions —S. V. Eaton.

Correlations.—Cui_p and BELLAMy™ have done a very interesting piece
of work on correlations in plants. They can break up correlation effects by

** HAwKIns, L. A., and Harvey, R. B., Physiological study of the parasitism of
Pythium presi Hesse on the potato tuber. Jour. Agric. Res. 18:275-297.
pls. _— Mags 2. 1919.

C. M., and Betramy, A. W., Physiological isolation by low temperature
in Peers and fort plants. Science §0:362-365. 191

358 _ BOTANICAL GAZETTE [APRIL

ooling 2-3 cm. zones of petioles and stems to a temperature of 2.5-3° C. In
Bryophyllum, when such zones of the petiole are cooled, the broken correlation
is manifested by development, not only in the notches of the leaf treated, but

McCatun’s view that correlative effects are brought about by conduction of
stimuli, mainly inhibitory stimuli, and not by movements of materials.—
M. CROCKER.

. Fermentation—EvLer and SvANBERG” made a study of alcoholic fer-
‘mentation in an alkaline medium in which P=8. Top yeast and Torula gave
about equal weights of carbon dioxide and alcohol, each equal to 30-33d of
the weight of the sugar fermented. Glucose, fructose, and invert sugar were
fermented with about equal speed, mannose about 30 per cent as fast, and
galactose very slowly. Invertase is active in this medium and maltase inactive.
The following are the maximum alkalinities in which cell division occurs in
the various yeasts: Frohberg Unterhefe B., Pa=7.7-8; Brennerei Oberhefe
m= B. Il, Pa=7.3-8.4; Sacch. ellipsoideus, Pa=7.9; Pseudosacch. apiculatus,
Increase in weight occurred in S.B. up to Pa=8.5. For Frohberg
eck H the full curve of acid sensitivity was reeiaren out and the
optimum was found to be at Pa=5.—W. CROCKE

Exudation of water by leaves.—Miss Fioop* has recently investigated
the exudation of extremely pure water by the leaf tips of Colocasia antiquorum.
Examination of sections of leaf tips showed no membrane, or other structure
which might act as a filter, between the vascular system of the leaf blade and
the pores leading to the tip. Solutions of India ink, gelatine, and starch
were forced through the vascular system and exuded at the tips. Exudation
from leaves attached to the plant continued at the normal rate when leaf tips
were anaesthetized. Miss Fioop is of the opinion that cells lower down in
the plant are responsible for the secretion and filtration of water, but finds no
evidence for the existence of such cells except in the root.—J. M. ARTHUR.

Colorado grasslands.—Reviewing the investigations of the grasslands of
Comrade by himself and others, RAMALEY” enumerates all the associations

™ Ever, H., and SvANBERG, O. cpr eects foie iiber Zuckerspaltungen.
Hoppe-Seyler Zeit. Physiol. Chem. 10§:187-239. 1

* FLoop, Marearet G., Exudation of water ne Colocasia antiquorum. Proc.
Roy. Dublin Soc. (N.S.) 15: pls. 2. 1919.

* RAMALEY, Francis, Xerophytic PSE at different altitudes in Colorado.
Bull. Torr. Bot. Club 46:37-52. figs. 2. 19:

1920] CURRENT LITERATURE 359

that have been described. He also gives a brief synopsis of the factors most
prominent in the control of such vegetation, and some of the more important
floristic differences which characterize the grasslands at different altitudes. A
notable reduction of species is manifest with increase of altitude, the estimate
running from 160 species for the mesas, 139 for the foothills, and 107 for the
montane, to 50 for the subalpine. A systematic list of species is given with
indications of their occurrence at different altitudes. The whole, including the
bibliography, forms a most useful contribution, summarizing 8 present state |
of our knowledge of these plant communities—Gro. D. FULLE

Biology of Fomes.—WHITE™ has made a comprehensive study of the
widely distributed Fomes applanatus, and finds that it attacks practically all
deciduous trees and several conifers, causing the destruction of large quantities

wood annually. It produces basidiospores only, which are not of the
ordinary type, being “yellow, papillate, thick-walled chlamydospores within a
thin hyaline wall.” Spore discharge is enormous and continues for a longer
period than recorded for any other fungus, being continuous day and night
.for about 6 months. There was no difficulty in making artificial cultures,
and the appearance of the rotted wood makes it possible to distinguish the
attack of this fungus from that of any other form. oe and
chemical details of the attack are fully described —J. M

cology of fungi.—Studying the influence of altitude upon parasitic fungi
from collections made by FRAGosco in Catalufia, Spain, and by himself in
Barreges, DurFRENOY™ found that the Pyrenees are not a barrier to the dis-
riepursas of fungi, although ee | are wagons differences between the fungus
- flora of the closely adj in. Heconcludes that there
are species peculiar to the plains and to the mountains, as well as those common
to both habitats. The determining factor in altitudinal distribution seems to
be neither humidity nor temperature, but radiation. The mountain species
are either more highly colored or are found on more highly colored hosts. He
was unable to determine any effect of altitude upon the resistance of the
host.—Gro. D. FULLER.

Pennsylvania trees.—The fact that within 5 years ILLick’s* tree manual
has reached its third edition is a striking testimony to its excellence. The
first part of the volume is devoted to a general discussion of forests, their
structure, development, care, and value receiving careful consideration, and

» Waite, J. H., On the biology of Fomes applanatus (Pers.) Wallr. Trans, Roy.
Can. Inst. Toronto 1919: 133-174. pls. 2-7.

t DuFRENOY, J., Les conditions écologiques du développement des champignons
parasites. Etude de géographic botanique. Bull. Soc. Mycol. France 34:8-26. 1918.

Itxick, J. S., Pennsylvania trees. 3d ed. pp. 235. pls. I-129. figs. 120. Harris-
burg: Dept. Povssicy Penn, Bull. rz: 1919.

360 _ BOTANICAL GAZETTE [APRIL

is illustrated by many very appropriate photographs. The form and structure
of trees are also carefully considered. The second part is devoted to a manual
of the trees of the state, and is well equipped with keys, glossary, and illus-
trative drawings. A noticeable feature of the illustrations of the individual
species is the drawing of the buds on a large scale. It is safe to say that it
will take a first rank among the numerous tree manuals now available.—GEo.
D. FULLER.

Montane plants of the Rocky Mountains.—RypBERG,* in continuing his
studies of the flora of the Rocky Mountains, has added to the articles already
noted in this journal’4 an investigation of the distribution of the montane
species. He finds about 1900 species in this zone, of which one-half are to be
regarded as typical inhabitants of this area. Less than 15 per cent are trans-
continental, while 53 per cent are endemic. A close analysis is made of the
constituents of the flora peculiar to the northern and southern portions of the
region as contrasted with that common to both.—Geo. D. FULLER.

Sedge associations in Colorado.—In studying the sedges of northern
Colorado, RAMALEY*s shows that the genus Carex not only is of decided impor-
tance, but that species of this genus dominate many plant associations, particu-
larly in the montane, subalpine, and alpine regions. These associations are
either hydrophytic or xerophytic in character, and represent early stages in
succession, for as mesophytism is approached the sedges are replaced by

om
listed, 20 are classed as Artic te 15 as xerophytic, and g only as meso-
phytic.—GEo. D. FuLLE

New African plants.—ENcLER,* in continuation of his studies of the
African flora, has described 45 new species of Sterculiaceae, 40 of which belong
to Hermannia, 29 new species of Guttiferae, and 3 new species of Violaceae
(belonging to Hybanthus).—J. M. C

A new genus of Umbelliferae.—Tuettunc” has described a new genus
(Scandicium) of Umbelliferae from the Mediterranean steppe region and
Western Asia, based on Scandix stellata a In addition to the species,
numerous varieties are described. aT. Me

3 RypBere, P. A., Nici notes on the Rocky Mountain region.
VIII. Distribution of the montane plants. Bull. Torr. Bot. ret prs 295-327- 1919

* Bot. Gaz. 62:83-84. 1916; 63:423-424..1917; 6§:195. 1918.

*s RAMALEY, FRancrs, The réle of sedges in some Colorado plant communities.
Amer. Jour. Bot. 6:1 rare te fig. 2. 1919.
: a Encte, A., Beitriige zur Flora von Afrika. XLVII. Bot. Jahrb. 55:350-49°-
919.

HELLUNG, A., Sca poli ein neues Umbelliferen-Genus. Sonderabdruck
aus Fedde, Repertorium.16:1 15-22. 1919.

VOLUME LXIX NUMBER 5

te
DOTANICAL GAZETTE

MAY r920

TEMPERATURE AND RATE OF MOISTURE INTAKE
IN SEEDS"
CHARLES A. SHULL

(WITH FOUR FIGURES)

Introduction

Some years ago BRown and Wor ey (1) published an account
of some experiments dealing with the influence of temperature on
the rate of moisture intake by seeds of barley. They found that
the value of Q,. for the intake of water is high, approximating that
of the van’t Hoff law. They interpreted this as indicating that the
rate of water absorption through a semipermeable membrane is
conditioned by some chemical change which occurs as the tempera-
ture rises. In discussing the probable nature of this change they
intimate that the water molecule is probably simplified as a result
of the temperature rise. In doing so they in a measure accept
ARMSTRONG’s hydrone theory of the structure of water. Cold
water, according to this conception, is composed of complex mole-
cules having at least several H,O groups combined into a single
molecule. These more complex molecules are supposed to break
down into simpler groups as the temperature rises; the water
becomes less viscous, and is able to penetrate the semipermeable
Coats of barley seeds more rapidly. The velocity of water intake

* Contributions from the, Botanical Laboratories of the University of Kentucky,
o ft

261

362 BOTANICAL GAZETTE [MAY

was calculated from the tangents of the curves of intake, using
a string and protractor for measuring the tangents. This is a
very crude and inaccurate method, especially in unskilled hands,
but one easily used. They assert that the velocity of water absorp-
tion is almost exactly an exponential function of the temperature.
A short time previous to the appearance of this work the
- writer (3) had found that the seeds of Xanthium have semipermeable
coats, and experiments on the influence of temperature on the rate
of moisture intake by these seeds were in progress at about the
time that Brown and Wor LEy’s paper appeared. The results of
the work, however, did not receive careful mathematical considera-
tion until about two years later, when it was found that the con-
clusions reached by BRown and Wortevy from their work on barley
seeds could not be drawn from the data which had been obtained
from Xanthium seeds. A preliminary report of the work was
made before the Botanical Society of America at the Columbus
meeting in 1915. The data which had been obtained indicated
that the value of Q,. was approximately 1.5, somewhat higher
than the temperature coefficient of diffusion, but notably lower
than that of chemical processes. This situation is very similar to
that later reported by DENNy (2) for the effect of temperature on
the rate of permeability of certain plant membranes to water.
Shortly following the Columbus meeting a few tests were run
on seeds of Xanthium having a somewhat different environmental
history. Mainly, the seeds were older than those previously used.
The intake curves did not check very well with the former data, —
and it was thought desirable to repeat the experiments with seeds
of the same species of Xanthium but of different genetic origin and
environmental history. In this way it was felt that data might
be obtained regarding the variability in the rate of water absorption
in these seeds. The data which have been accumulated have been
subjected to a critical analysis, principally to insure accuracy in
the measurements of tangents. At the same time the possibility.
of a rate law has been kept in mind; but froma study of absorption
in a number of cases I have decided that it would be unsafe or at
least premature to propose a rate law on the basis of data now
obtained. At the same time, the formulae presented may have

1920] SHULL—SEEDS 363

rather wide application, and deserve to be considered by those
interested in the problems of absorption. While on the theoretical
side certain features of the work have been disappointing, it will
be worth while to give a somewhat detailed account of the experi-
ments, as a contribution to our knowledge of the facts concerning
the intake of water by dry organized matter.

I wish to acknowledge my indebtedness to Professor S. P.
_ SHULL for valuable assistance with the mathematical part of the,
work. He has given generously of his time during the last five
years to a painstaking analysis of the data, which has made possible
a degree of accuracy otherwise unobtainable, and without which
the general significance of the data could not have been fully
appreciated. He has also tested many hypotheses as to the influ-
ence of factors upon intake rates. The principal part of the
experimental work was done in the Laboratory of Plant Physiology
at the University of Kansas, and part of it at the University of
Chicago during the summer of 1914. The privileges of the Hull
Botanical Laboratory for this work were much appreciated.

Materials and methods

The experiments were carried on with the lower seeds of
Xanthium pennsylvanicum Wallr., and the naked cotyledons of
several varieties of peas, the Ganads green field pea, the Tom
Thumb garden pea, and the Small Scotch Yellow pea of commerce.
The cockleburs were chosen for their semipermeable coats, and
the peas because the elimination of coat effects is easy. At first
seeds of Xanthium were collected in the field; but these were soon
replaced by pure line seeds grown on the Leweding grounds of the .
University of Kansas in 1913. It was felt that such seeds might
be more valuable than those of mixed genetic origin, more uniform
in behavior, and the absorption data therefore more susceptible
to mathematical consideration. After it had become evident that
age, environmental history, genetic origin, and other factors might
influence the intake phenomena, seeds were obtained from plants
growing near the writer’s home in Lawrence, Kansas. Slight
differences in the shape and appearance of the seeds of different
plants indicated possible lack of genetic purity, although the

364 BOTANICAL GAZETTE [MAY

plants by all their external characteristics were unmistakably
true X. pennsylvanicum. ‘These were used in the later work to
give an idea of the variability to be encountered in the moisture
intake by a given kind of substance.

The absorption took place in test-tubes of distilled water which
were kept at the desired temperature by standing them in a water
bath. Care was taken, particularly in the later work, to have the
seeds at the same temperature as the water when they were first
brought together. Three temperature curves are discussed in
the present pert 5, 20, and 35°C. Tests were run at 5° intervals
from 5° to 50° C., but these three stand near to the temperatures
used by Brown and Wor -ey, and afford a satisfactory basis for
comparison. The others have been omitted. In all cases the
fluctuation rarely exceeded 0.25° on either side of the chosen
temperature during the significant period of intake.

At close intervals the seeds were removed from the water,
dried uniformly and quickly on filter paper, and weighed with
analytical accuracy. The time periods of immersion were made
as sharp and accurate as possible, and the time during which the

seeds were out of the water was reduced to the lowest possible
limit. The drying required 10-20 seconds usually, and the weighing
was done as rapidly as accuracy permitted. During this period
the seeds had some Spporranity: to change from the temperature
of absorption in the 5° and 35° tests, but histeresis of the seed
colloids would tend to prevent serious alterations in colloidal
aggregation during the brief interval involved. The errors due to
such changes would be slight. The intervals between weighings
were made short throughout the work. The first weighing was
always made at the end of 1 minute to catch the very rapid initial
intake. Succeeding intervals were usually 10 or 15 minutes, oF
longer when continuous attention could not be given to the work.
The time intervals used will always be indicated in the tables with
the absorption data. In all cases the time needed for drying and
weighing was subtracted. This weighing at intervals was con-
tinuous in the case of Xanthium seeds until the intake was well
above 35 per cent out of a possible 50-55 per cent. By the time
40 per cent of water had been taken in, the velocity of intake always

1920] SHULL—SEEDS 365

showed marked and increasing depression, due to approaching
saturation. The split peas take up a considerably larger per-
centage of water than Xanthium seeds, and the intervals were con-
tinued until intake significant for the problem in hand had ceased.

cent
703 20°

50;
£

Pa
AZ
tA

aS
id

Se ee eS ee ee
Fic. 1.—Curves of moisture intake: lowest curves, 5, 20, and 35°, by Xanthium
seeds; poe curve, split peas, 20°; horizontal lines show points of equal intake where
tangents were measured.
The value of close time intervals, despite certain obvious disadvan-
tages, will be indicated later in discussing the work of Brown and
Wortey.
The velocity of intake at any given moment has been calculated
from the tangents to the curves. By reference to fig. 1 it will be

366 BOTANICAL GAZETTE [May

seen that horizontal lines cut the three temperature curves for
Xanthium seeds at 5, 7.5, 10, 15, 20, and 25 per cent of intake.
The tangents were determined at the points where these horizontal
lines of equal intake cut the curves. From the velocity of intake
at the three points cut by each horizontal line, the ratios of velocity
have been derived, and from these ratios the mean value of Qy.

The string and protractor method of measuring tangents was
found to be too crude and inaccurate, especially where the angle
of the tangent is high. The English investigators, however, used
the method with fair success. Their measured tangents deviate
but slightly from tangents calculated accurately for the same points
in their curves, but in less skilful hands serious error might occur.
In this work all tangents have been calculated from the known
algebraic formulae of the curves, and all inaccuracy of measure-
ment has been thereby eliminated.

In some cases data have been discarded, but only when it was _
entirely justified, and necessary from the mathematical standpoint.
Whenever during the course of an experiment any of the seed coats
became ruptured, the curve of intake was distorted because the
surface of intake was greatly increased. Mathematical analysis
of such data is impossible or meaningless. Such series of data have
been discarded, and only those have been used which went through
the many dryings and weighings without injury.

Experimental data

The data presented in table I were obtained with seeds from the
first generation of a pure line of Xanthium pennsylvanicum Wallr.,
from the same line as was used for work on soil moisture published
previously (4). The general characters of the type used have been
described as type II in a discussion (5) of physiological isolation in
the genus. The series of data chosen for mathematical considera-
tion were drawn from a large mass of data some time before the
analysis was made, solely on the basis of maintenance of satisfactory
conditions during the period of observation. Ten lower seeds of
X. pennsylvanicum were used in each case.

The series at any given temperature were fairly uniform with
these seeds at the time the work was done. The variability to

1920] SHULL—SEEDS 367

be encountered is illustrated very well by the duplicate tests
presented for 5° C.

The earlier work on split peas was not very satisfactory. They
are more difficult to dry uniformly, and small pieces are more easily
lost from the edges of the cotyledons during the drying, especially
at higher temperatures. In table II data are given for two tempera-

TABLE I
WATER INTAKE OF Xanthium SEEDS IN PERCENTAGE OF AIR-DRY WEIGHT
is? 20° 38°
TIME
I II I I
Se asain ty 1.124 1.36 1.73 2.45
+5 thmutes; os: 3.814 4.23 6.806 10.89
3° minutes...... 6.226 6.18 11,00 16.41
as Rea oc, 544 8.32 14.55 21.81
60 minutes. ..... 10.747 Q.92 17.38 26.38
75 minutes... ... 12.521 II.90 20.20 30.21
90 minutes. ..... 14.202 13.05 22.81 33-890
TO5 minutes...... Is -7TO 14.65 a5.42 Ay ee
120 minutes...... ‘17.101 15.81 27.44 39-
135 minutes...... 18.724 17.65 29.32 41.87
150 minutes...... 20.182 19.81 1.06 43.25
ROS marie 8 Eo ee 0.90 BARRE BO, Cio ah eas
160 minutes...... 23.002 an: 37 34-54 45.24
SOS SHUNT ON oe a caw 23.40 SOEs le ee tay
210 minutes. ..... 25.159 24.54 ey ier 48.46
ae MULES Oe for os eee ee 26.54 ELLY Saag, pies Sees ie rears
240 MOS. ie $0 500 4 ee BO. 30) Teast
OSS MiNnUteO so. Aes Na esd is eh, Ree ye Oe a ee
270 minutes. ..... SU ONE 2s Airis on ats WOR Ae
MUCGS ie I cai eae = 20°50) feck as
300 minutes...... 20.7825 a Se PLO ty cee) mS eee meen et
339 minutes...... 31.304 BE OO iN a ee eu LEM eee da net oe
SOO Mie Ng ea Oe BRR re ees
39° minutes...... SS2550 (fe es WATS 2 ee ee cere enees
450 minutes...... SECOTE SNOT a Sra oe wera p ae Yee Geese Cle Ce Hisld ds o's oees
510 minutes...... SOARES a Oa Lee ea sees ASP OE Sige nae eee
o7o Mminutes.'. oo... SAF Pe as eas eee tee Ue Vee er er ese
18.5 hours. ..... 45.020 Dat wel eg CoP ee A Cpe ahs be oe ot OER
AES ee Relea Ge oe A Levers eee bev ces OP 98 OSE vee c ets

tures only, 20 cotyledons being used for each measurement. Curves
of intake have been plotted for the cocklebur seeds at all three
temperatures, and for the split peas at 20° C. in fig. 1. The split
peas are included here merely to show how various substances
differ in rate of intake at the same temperature. The rate of

368 BOTANICAL GAZETTE [MAY

intake, of course, varies with physical structure, chemical composi-
tion, state of aggregation of colloids, etc.

TABLE II
WATER INTAKE OF COMMERCIAL SPLIT PEAS (VARIETY
UNKNOWN) IN PERCENTAGE OF AIR-DRY WEIG

Time 20° as
Pee a as 4.25 5.3
£5 MBUteS oe. ee 16.20 20.83
30 Minutes 2 e. 23.84 33.04
AS TUNES | ee 30.14 41.94
eS 35-32 50.30
7s mmites i ce 40.30 57.60
mutes: i. 45.22 63.77
ro5 minutes. 52 67.81
E20 TUNULES oo oe 57-50 71.00
Tay TOIOS. ee ss GEiae oo oe es
250 Minutes. |. es. i. Oe ah oe ey
mGs nutes 68.66 74-32
780 munutes. Se: Yj se Waters [ars Pain PCE EY Es
TOs minutes... 2. oo. a Ts hes i ae ae
2 le. Serer WER Oe eas he pas
DUG WR, i eo ee gc 76.11
330. minutes. ........ PRO ee eo
22 OWS ae 77.50
aa, 8 OONs, 2 oo, TAO Vota. ion vas ca
TABLE III
WATER INTAKE BY Xanthium SEEDS IN PERCENTAGE OF AIR-DRY WEIGHT, 5° C.
fcbooness I rit III IV ¥ caarenae
ae 1.30 1.90 %.33 2.19 1.57 1.64
Bid ee 3.20 a,46 z.90 3.87 3-33 3-44
102253253 4.74 4.47 5295 5-92 4 4.97
$Elo cscs: 6.20 $.6¢ 6.88 6.87 6.15 6.22
fo Ree 8 8.13 9.02 9.72 8.92 7
PSE ene 10.79 10.43 11.09 11.76 10.87 10.82
Pesce eee 12.85 II.79 13.02 13.00 12.81 12.59
Seer eds 15.68 14.50 15.53 16.73 15.89 15-43
1900. 18.36 16.87 18.05 18.85 18.09 17-77
T50. 2, as 21.04 18.97 20.56 20.67 20.29 19.99
ph er eS 88 20.73 22.71 22.42 22.30 21.86
BAO See Cees 26 55 24.39 25.89 26.08 26.26 25.42
sere eee 30.22 27.51 28.99 29.07 29.71 28.67
200.665. 33-50 30.28 32.03 31.92 32.91 31.67
OU Ds leet ne Se 37.38 32.26 34.91 35.14 35-30 34-55
eae we ems 49.93 6.86 39.20 39.96 40.70* 38.56

* During the last two hour period in no. V the mean temperature was about 6.2° C.
__ After the earlier work had been analyzed, some tests were made
on old seeds remaining on hand, in an effort to check up the ini itial

1920] SHULL—SEEDS 369

absorption rates. As the seeds seemed to show a somewhat differ-
ent behavior, tending to decreased intake rates at the start, it was

TABLE I
WATER INTAKE BY Xanthium SEEDS IN PERCENTAGE OF AIR-DRY WEIGHT, 20°C.
Solent) I I II IV Vv be eed be pus
Ene or oe t77 1.95 4.32 2:35 2.74 2.08 2.38
iy are Uren ay 4.60 5.28 6.15 5-56 5-44 4.04 5.34
| 58 Sila aa eee 6.76 8.21 8.59 8.26 8.21 7.41 7-94
ER See are ae 11.44 10.45 II.07 10.28 10.27 10.32
BO es ¥t.70 |. 13:88°|. 14.00.) 44.08 | 16.57 | 20-51 | 1g.G4
SR rik 1S.70') 19, 16 27507.) 18.82) 22.15 | 20.68 1518.54
et eer £7.61 20.33 | 20255 | SE. 85 1° 24-Be | 39-077 at. t3
Wee ke eee aes 19.04 | 22.29 | 22.95 4.290:}: 26.90 | 26.27 | 23.64
Melee wy koe 21.81 64.63 | 25.78 | (26.46 1.29.18.} 25.8 26.04
PUR Re. eee. 26 78: | 26.88 | 27156] 20,%0-| 31.91 |. 31.9 | 28.17
BAO ee 25.89 26 S41 20.88 1 35.101 32.501. $3.42 | 30.44
ES geeks 26.00 | 29:45} 38.001) 20.051 38.471 35.65 32.16
PaO eh eu, 20.53 | 32-50 |. 33.20 | ~ 34.301 36.10 | 37.84 1 33-72
alee see 31.35 | 34-31 | 34-56] 35.75 09 | 39.27] 35.20
Oe aa 89 | 35.48 | 35.84 | 37-20] 38.77] 40.96 6.66
Mes ar 34.32 | 36.46 | 36.91 | 38.11 | 30 42.46 | 37-77
BION ev eviem yo ouly eu a 37. 54.| 395991 36°01 | 40,50 | 43.06 8.79
Sh ae ae aren penne bhi’ eS 86 | 40.01 AT AAT (O69 2 fie cass
ee a2 08h 39-45 | 40.86 | 42.33 | 45.77 | 40.64
Bee yay ess eee 40.27) 40 Ga al 6501 Ad SO ee
TABLE V
WATER INTAKE BY Xanthium SEEDS IN PERCENTAGE OF AIR-DRY WEIGHT, 35° C.
Tt Percent-
duinntess! 1 I UL IV Vv VI Vit | VII | age of
Tics) 2.2642 AO OR 9s ee Be AO eee LS. 9O 4 2.83
§-- 4] O35 | 27-3 ys a a DR 8 Sa eae I 92] 7.04 | 7.46
ROS sf Lu 22 112-39 | teao 4 17, 9.78 | 10.25 | 14.98 | Ir.3o | 11.82
IS. - | 34:23 | 44.50 | 20.2471 14.25 1.12.31 | £2.70] 18.47 | 33 15.11
20, 210.88) | 1736: | 93-42 1 79.55 | 14: 15.34 | 21.41 | 16.51 | 17.84
$0... | 21. 28 8 | 27.77 | 21.85 | 10.40 | 10:95 | 25-44 | 21.25 | 22.45
40....] 25.14 | 26.42 | 31.94 | 25.45 | 23.67 | 23.52 | 28.86 | 25.44 | 26.32
ss are a) 30.18 | 34.90 | 29.25 | 27.09 | 26.82 | 31.81 | 26.69 | 29.70
60....} 32.39 | 33.79 | 37-66 | 32.85 | 30.16 | 30.12 | 34.68 | 31.04 | 32.95
7O....) 35.15 | 36.64 | 40.01 | 35.20 | 33.11 | 33-29 | 37-21 | 35-05 | 35-71
80....| 37.29 | 39.48 | 42.23 | 37-76 | 35.50 | 36.31 | 30-33 | 37.21 | 38.13
99....] 39.23 | 41.78 39.70 | 37.602 | 38.79 | 41.18 | 39.24 | 40.19
100... .| 39.50] 43.78 | 45.53 | 41-22 | 39-67 | 40.92 | 42.75 | 41 41.78

felt that studies should be made of absorption in ordinary field
material, with the purpose of disclosing the variability likely to
occur at a given age of seeds. These experiments were conducted

370 BOTANICAL GAZETTE [MAY

through a period of several weeks on seeds ripened for about three
months. To reduce the time element in drying and weighing, only
two seeds were used in each test. At the same time care was taken
to have the temperature of seeds and water equal at the beginning
of the measurements in each test. Table III shows the results of

TABLE VI
WATER INTAKE IN SPLIT PEAS IN PERCENTAGE OF AIR-DRY WEIGHT

ve Tom Thumb Yellow Green Canada field pea Small Scotch Yellow

Gatmaten) o
5" 20° 35° s 20° 35° ig 20° 35°

I 3.00} 3.76; 4.3 3.1% | 4,00.) 8.541 4-771 5-38). 3-77

5 7.28 8 10.19 7.08) G.20 |r i401 7.26 | 13.26 | 16.34
10 10.48 | 12.63 | 14.90 | 11.73 | 13.49 | 20.30 | 11.50 | 19.98 | 26.54
15 13.05 | 15.50 | 18.69 | 14.61 | 16.68 | 25.62 | 15.58 | 25.09 |. 33-65
BOs idtin ee wate he ees SPAS ee ies SO O48 Vis has 1.54
30 16.79 | 21.15 | 27.78 | 19.33 | 22.98 | 41.59 | 22.48 | 33-690 | 54-23
ADSI ae ae v7 Me Wy Saeeeme OREO Nee AR Ce 9 a eso cia ty 3-75
45 20502" F 26. 161 oe AQiON EOS A tee ct DULY ae GA nara irs mem 8
Po Sap ey Mert Deo Us: Lacie VOR ee aes SUNN Bae a 4s Of 1,
SO tes ety ces ee S090 tc os pe ease BA Pacino wapers 4 talp

60 22.83 | 30.11 | 42.34 | 26.35 | 34:96 | 80.40 | 29.82 | 50.80 | 73.56
v2 Megs CERES DN DRA Cay te BO.34 boas [eee aes OAC tee aris beet 74.04
75 Py Aa be ek ty One 40.4% § a9. 801. 05.3 46.37 |: 58.24 |.» ++«s-
cf eee OS feu ers te =e pg Sas Clereere ans See
go 28.09 | 37.28 | 64.27 | 32431 | 50.41 | 94.68 | 40.00 | 69.59 |-------
R00 oS eevee eae Ol Gg bos ee Oe 1g Pome Ge Diener a EEN a
TOR. Sa 90.58) As aA pie 38.98 464096 10500 oY, 43.37 | 68.10 |...--++
120 83.00-)- S108. SRIF b 95506 4 ss 45.66 | 70.34 |...---+
RR ee ag 7 ie DO ON alee ee Mc O48 facies. 48.85 | 72.58 |.:---->
150 30.8r 1 G2.60 ti... A285) S200 jo. ee SURO eee oe
1085 8 Gs or ie 2s ayes Gaz) Doge tae) lee Fae an Bape Aegean SA. OF lye i oe ee
180 4090 1:90.94 |. 025... EE oe: Aegan Camere ah Pieran ds ee
210 $4.92 bocce sy slea cee BS Oy ose acl bere ee hae Pees pee eer ee
225 Sei oa FOL cee EL eee oabnct, tg SO ean ae G250 Locke he es
240 49.40 MY To Va ca a a ee eee
270 BACAZ Coal ee, OB 08s ooo io, ee ce ee ees ope oe
300 COI ee Fo BOE be ie gE es ba thon wines Pe we
330 PR Pe Ri lo dc Ole Oe Fas oi has ue 1 cas wiae cP ee Wedee e eet?
BOG a eee any coe ISL a he eae po a ech ecs bon 66 Of fies os eee
360.. PROT ee ee Oe as ae ls ie Pe pr Pe
390. . PROT Lets clon ea th eae A oeig es Adin sys hiwsdees [one oe eee

five experiments at 5°C. In the last column is shown the per-
centage of the averages of intake. This percentage of the averages
must not be confused with the average of the percentages, which
would give a slightly different set of figures. In analyzing these
variable groups we have used the percentage of the averages in
attempting to construct a mathematical curve that would follow

1920] SHULL—SEEDS 371

the data. Similar groups of data for 20° i 35° C. are shown in
tables IV and V.

The absorption data for the split peas were found on examina-
tion to be very difficult to analyze, owing to changes in rate of
absorption, due almost certainly to internal physical changes in
the seed. No attempt was made to carry out the work in so
detailed a manner as in the case of Xanthium seeds. Enough has
been done, however, to make it worth while to put the data on
record. The results with three named varieties of peas at the
three chosen temperatures are given in table VI.

Mathematical discussion

For purposes of mathematical discussion it is not considered
essential to plot any curves of the data in addition to those given
in fig. 1. Only such curves are used as are necessary to an under-
Standing of the discussion. Anyone desiring the curves can easily
plot them from the data.

In view of the fact that Brown and Wor ey considered the
curves of water absorption in Hordeum seeds as paraboloid run-
ning out toward a common asymptote, attention was turned
first to the type of curve which would most nearly fit the
data shown in the preceding tables. Even a casual examination
of the data of tables I and II shows that the curves are not simple
ones. Since the situation is somewhat simpler in the case of
Xanthium seeds than in the split peas, the data from the former
will be considered first.

XANTHIUM SEEDS

During the first moments of absorption (40-60 seconds) the
entrance of water is exceedingly rapid; but in a short time the
rate breaks sharply to a lower rate, which then decreases slowly
but rather steadily during the main part of absorption, until
approaching saturation begins to affect the rapidity of intake.
In Xanthium seeds saturation occurs at about 50 per cent, and
the final break in the curve caused by approaching saturation
manifests itself at about 35-40 per cent, as is shown in the figures.
The whole curve is thus apparently a composite curve made

372 BOTANICAL GAZETTE [MAY

up of at least three component curves. The general relations of
these to one another in the composite curve are shown graphically
in fig. 2, which has been somewhat exaggerated, especially in respect
of the first curve, for the sake of clearness. The effect of the initial
rapid intake is to throw the main part of the curve upward from
the base line. Careful examination showed that it was not possible
to find a parabolic curve that would follow the data at any tempera-
ture. The problem then was to find an empirical formula or
equation or such a combination of equations as would very closely
approximate the given data of observation. This was necessary

Se
e

Fic. 2.—Curves showing composite nature of moisture intake curves in Xanthium:
first curve exaggerated; oa, initial intake; bc, main curve; de, approaching saturation.

in order that precise and accurate methods of measuring tangents
could be substituted for the uncertainties of the graphic method
used by Brown and Wortry. The only proof we have that any
equation or group of equations is adapted to such use lies in a
comparison of the experimental data with corresponding values
computed from the equation under consideration. As it is impos-
sible to avoid slight irregularities in obtaining data, the equation
must be so determined as to distribute the irregularities rather
evenly on either side of the curve, as one would expect from the
laws of chance variation.

Early in the investigation an equation was discovered which
could be made to approximate very closely the series of data

1920] SHU LL—SEEDS 373

obtained by measuring the total increase in weight due to absorp-
tion for different periods of immersion. This equation takes the
form y=a log,(bx+1)+c, in which y=the total percentage of
intake, and x=the length of time of immersion, a, 6, and c being
constants. In the later work it was found that a still closer approxi-
mation could be obtained by the employment of two equations of
this form tangent to each other, the first equation representing the

TABLE VII
ALGEBRAIC CURVE FOR ABSORPTION DATA A ee RPTION
IN PERCENTAGE OF AIR-DRY WEIGHT aieeen
Time Data low Computed Data high
Lminvtes se eee 1.055 I.124
+S minutes Soe 3-739 3.814
30 minutes...... 6.226 Pe Cc aia | Rs arava ware
5 minutes...... 8.544 BRAS Cte as ut
MULES Ss oe 10.591 10.747
mg A oe ye eG 12.456 12.521
OO Minutes. erie oe 14.169 14.202 *
FO§ TmMutes se: 15.710 sie Bk See i eee mit rer ear al
20 minutes...... 17.101 P9900" uae, ee eet
Tse minutes: ch Yo ee 18.603 18.724
150 minutes...... 19.810* 10,0008 i
165 minutes...... eat i Caley all ae gaa
100 DALE 1S ea as 22.265 22.270*
TOS wtes. Co ee 23.356 23.400*
° lees a ae ee 24.304 24.540*
POS. i ee ce. 26.327 6
270 minutes...... 27.905 25008 ee aes
WEES 65d 29.182 BO 082 Foe as baw pa
330 Minutes. ose aly oe 31.247 31.304
390 minutes...... 33-159 34,007 | Wi cccen eh ae
450 minutes...... 35.072 BO AIG boca pas
I ites. oc. 36.486 BOOSAS isc asi. os
57° minutes...... 38.400 WO ROR he i as os
I eS Ns 45.020 Ade s&s SEA A eee Seen

* Data from series IT.

earlier data, the second representing the later data beyond the
point of tangency. In one case it was found advantageous to
introduce a third equation of this kind. The closeness with which
this equation can be made to approximate the experimental data
is truly surprising. It has been applied to the data furnished by
Brown and Wor ey for barley seeds, and approximates their
data more closely than the calculated values they obtained from
their formula. It must not be supposed, however, that the formula

374 BOTANICAL GAZETTE [MAY

can be successfully applied to all cases of absorption, or that it has
any special significance beyond its applicability to measuring
tangents accurately in all curves to which it fits.

In dealing with the data of table I it was found desirable to
partially combine the two series at 5° C. because of irregularities
in each set. As the seeds used in these early tests were not reduced
to water temperature before immersion, some tests were run for

TABLE VIII

ALGEBRAIC CURVES FOR ABSORPTION DATA; INTAKE IN PERCENTAGE OF AIR-DRY
WEIGHT (Xanthi um)

20° C a5 6
Tm™E TIME Laborer a mR ESE RID GI
Data low| Computed | Data high Data low} Computed | Data high
TE yamute.-621) 3-73 P.Bat i. ee Iminute..| 2.45 2 BAO Ls A eens
15 minutes..|-.. 2. .3 6.481 6.806]. 15 minutes..|....... 136 | 10.89
30 MINUTES; [6h ia. 10.5 II.0o 30 minutes..} 16.41 | 16.471 |...-----
45 Minutes. |i... 4.213 fa Ge.) As MMLes,:| 5S 720 | . 21.81
60 minut 17.96 | 29. 20610 60 minutes..|}....... 317 | 26.38
75 minutes. .| 20.20 | 20.239 |........ 75 minutes..| 30.21 | 30.305 |.---+--:-
go minutes..}....... 809 | 22.81 | oo minutes..|....... 855 | 33-890
ros minutes. 25: %2 | 25. 56o7} 2.8 TOS Mantes. 1.52. 054 | 37-11
120 minutes..|....... 27.308 20 minutes..| 39.80 | 39.964 |.-.--->-
Fh mmutes. bso. 29.301 29.32 | 135 minutes..| 41.87 | 42.635 |..---+--
so Thinntes, |} 95 206-145. 167 be 150 minutes..} 43.25 | 45-102 |..------
165 minutes BO4 42.808 os 180 minutes 24 | 49-534 |---++->>
180-minutes..|....... 34.520 | 34.54 hou 48.46 | 72.348 |.-----+-
195 minutes..|....... 36.056 | 36.13
210 minutes a9. 4A) Sg S07 ivsa eas
226 minutes. .| 35.52 1 48 -6ad-105,..%...
24 ites 39.3 AOUIOS Ti eke
270 minutes. .| 40.98 | 42.634 |........
t 42.5 Ce a OR ie
330 minutes..| 43.95 | 40.934 |........-
360 minutes. .| 44.75 AL? US Pear aie
26 hours... .| 47.28 | 84.280 103.5...

corrections of initial intake with seeds at water temperature. The
result was a slight lowering of the initial intake at 5° C., and an_
increase at 35°C. These corrections were taken into consideration
in deriving the values of the constants for computing the theoretical
intake from the formula.

In the 5° C. curve the values ise the constants a, b, and c in the
equation given are as follows: y=48.5 log. (o.o98x+1)+0- 85-
The closeness of the intake computed from this avis to the
actual data is illustrated in tables VII and VIII.

1920] SHULL—SEEDS 375

The computed intake agrees very well with the experimental
. data until the absorption reaches 33 per cent, and from that on the
data fall more and more below the computed values. This
falling off of the actual intake marks the beginning of the effects
of approaching saturation. It is evident that tangents to the curve
may safely be computed up to about 35 per cent of intake, but
beyond that point the tangents could not be used for comparisons
of the rate of intake in different curves.

For the absorption at 20° C. the substituted values for the con-
stants make the equation read y=61. 5 logio(o.0136x-+1)+1.46,and
the corresponding equation for 35° C. is y=74. 5 logi(o.o184¢+1)+
2.25. The closeness of the computed intake to the data of observa-
tion in each case is shown in table VIII.

In the 20° curve the effects of approaching saturation first

manifest themselves at about 37.5 per cent, and in the 35° curve
at about 40 per cent of intake. In each curve the computed
values are strikingly close to the actual data. The uniformity of
absorption and the agreement of the calculated intake to that
observed has been a surprising feature of the work; and since the
final break due to approaching saturation is always at or beyond
35 per cent, I have felt confident of accuracy in measuring tangents
of the curves to that point.

In the later work the data could not be so satisfactorily repre-
sented by means of a single equation. By the use of two or three
successive equations, however, each joined to its successor in a
Point of equal tangency, a very close agreement between calculated
intake and experimental data was obtained. For the purpose of
calculating tangents, and rates of intake, this composite curve
is just as satisfactory as if it were developed from a single equation.

The 5° curve will be considered first. The three empirical
€quations used are as follows:

(1) y=14.3 logy (0.078%+1)+1. 398
(2) y=35.07 log (o.0121%+1)+4.195
(3) y=87.95 logs (0.0023%+1)+8.625

The first two curves have equal tangents for x=35.35, and
the last two for x=150.89 (minutes). The breaks in the curve

376 BOTANICAL GAZETTE [MAY

are very small. Thus, at the first break, in curve 1, y=9.605814;
while in curve 2, y=9.6056 at the common point of tangency
with curve 1. At this common point the two curves are only
0.000214 (per cent) apart. Similarly at the second break, for
curve 2, y=20.01634, and for curve 3, y=20.016284, a break of
only 0.000056 per cent. This combination curve runs remarkably
close to the data of observation and gives perhaps the best series
presented. The calculated and observed intake is shown in
table IX. Data in last column, table ITT. :

TABLE Ix

ALGEBRAIC CURVES FOR ABSORPTION DATA; INTAKE IN PER-
CENTAGE OF AIR-DRY WEIGHT (Xanthium), 5° Cc.

Time (minutes) Data low Computed Data high
Ba ee a is 1.64 TBO 3 fe ory was
Bees Cap ueeul. boudes uae AM hes Cass ores a
MOs eee cs 4.97 BOS hi aera
Spel Sera a eae 6.91 6.22
ce RAC Aap 8.97 i eee eee
RSet Oe FOVS2 ieee 4
OO oc eee uk 12.50 PPG eee esas
ew eee Ue PES he ae eee 15.42 15.43
120 . 17-77 E76 rca aes sec aps
Y (> ROG Pane Mapconm, Raita Mg ne Pe diye 19.96 19.99
POO voce eee erst a ee FEO esses eet
SAO oe eee ee ee ee 25: AT > 25.42
SOO eae ae Mn cs pos Eke Vs B07) AG eae cee yeas
Pte eS oe Bere ce 31.67 ines cee bee
BIO oes sw eae ea ae eared 34.46 34.55
BAO co aa. 38.56 S004) le vGesss canes

The data obtained with Xanthiwm seeds at 20 and 35° C. were
given similar treatment. Two equations were used for the 20°
data as follows:

(1) y=23.77 logs (0.088a+1)+1. 524
(2) y=57.13 logy (0.0132%-+1)+6.616

These two curves have tangents equal for «= 34.52, at which point
curve 1 has y=15.931972, and curve 2, y=15.931732, only 0.00024
per cent apart.
In the 35° data, also, two successive equations were used:
(1) y=34.92 logis (0.0983x-+1)-1.40
(2) y=73.05 log (0.0286%+1)+6. 53

1920] SHULL—SEEDS | 377
The point of equal tangency in these curves comes at %= 22.01,
and at this point in curve 1, y=19.28409, while in curve 2;
y=19.28407. The break therefore is only 0.00002 percent. The
agreement between computed and observed intake here is not
quite so close as in the 5° curve, but is still very good (sée table X,
the data for which come from the final columns of tables IV and V).

It is apparent in these later results, just as in the earlier ones,
that approaching saturation does not begin to interfere with
absorption rates until 35-40 per cent of intake has occurred.
It should be quite clear, also, that the equations employed run so

TABLE X

ALGEBRAIC CURVES FOR ABSORPTION DATA; INTAKE IN PERCENTAGE OF AIR-DRY
WEIGHT (Xanthium)

20° | se
Time TIME
(MINUTES) (MINUTES) f
Data low | Computed | Data high Data low | Computed | Data high
ae ne 2.38 B80 Fata ee Be i ee ea 2.83
Sy eRe Bea Aine ena 5.29 5-34 Sire rs a Pee A ox een
ee 7.92 S08 becees. « IOs foe es 11.82
AMR Rt Cree ne 10.21 10.32 EG cewek Te yee Seng © St ee
PO ee DL 14.64 TA(00s oe oo PR Mage 2704 1G TOO re ew,
Cape ees ee ad ESLIG.f 200 Gar 1 a0u 22.45
RR Me Pe pro QU. OG fi 347 AR ae 26.32
Sees 93-04") 29 00 fe ccs 8 SOC use.: 5.70: 26.70 Tee
Si gig ee RAG) Deira haa AG BA ty ions ee OS. CO ee 32.95
105. 26.17) 2516 oc rio Rares oie B59) | 3595 1s ce. es
So Se ea 30.14 S027 oe BO eet Boe Spel GG + Who Ae eRe
ROG PC TSG be ee Sa. g22168-4 00. 0... 40.10 | 40.796: }.< 5-5.
1 Beales Ge URN Greet 33:71 32.77 [100-2 44... Al 9 1 AS 08 Pes.
oo ee S590 BS °4O eae
a 36.66 1 3680 bo i

Close to the observed data that the velocity of intake can be
measured at any given moment with great accuracy. Instead of
plotting curves and attempting to measure the tangents graphically,
they have been calculated from the known formula.

The velocity of intake has been computed from the tangents
for six points on each temperature curve of intake. These points
coincide with those chosen by Brown and Wortey, as follows:
5, 7-5, 10, 15, 20, and 25 per cent of intake. The percentage
hourly rate of intake for these points, on each curve shown in
tables VII and VIII, together with the logarithms of the hourly
rates of intake, are shown in table XI.

378 BOTANICAL GAZETTE [MAY
TABLE XI
WATER INTAKE IN Xanthium SEEDS
5° 20° 35°
AKE
PERCENTAGE Velocity in Velocity in Velocity in
percentage | Logarithm | percentage | Logarithm percneon? Logarithm
hour hour . per

jan tk LOPE Ue 10.1705 | 1.0073 .0894 | 1.280792 | 32.8097 | 1.516002
Shey Po Peer 9.0322 | 0.955704 | 17.3838 | 1.240145 30.37 1.482445
PIONS OG 8.0214 | 0.904250 | 15.8304 | 1.199492 | 28.1116 | 1.448886
Meee... 6.3264 | 0.801157 | 13.1278 | 1.118191 | 24.0865 | 1.381774
Y20. ss 4.9896 | 0.69806 10.8866 | 1.036893 20.6376 | 1.314659
PTW. sees 3-9351 | 0.504056 9.0280 | 0.955592 | 17-6826 | 1.247546

In the later work the velocity calculated from the tangents is
expressed in percentage per minute, instead of percentage per

hour.

in tables IX and X, are given in table XII.

TABLE XII
WATER INTAKE IN Xanthium SEEDS

The velocities for the same six points, on the curves shown

5° 20° 35°
INTAKE ve = ,
PERCENTAGE elocit; Veloci Velocity in ;
ma a Logy Velocity parain Bon Log Velocity percentage Logs Velocity
bet minute per minate per minute
ee oe 0.27122 | 1.433322 | 0.64872 | 1.812057 1.17576 | O. 070318
a oe 0.18134 | £.258494 | 0.50920 | 7.706888 | 0.99707 | 1.998726
A bag ee 0.12589 | ft. 2 39968 | 7.601702 | 0.84554 7.927134
ymis......: 0.09066 | 2.957416 | 0.24624 | 7.301358 .608 1- 783947
Y*IG. 6. Las 0.06537 | 2.815378 19096 | 7.28094 0.44820 | 1.651472
D daa Cer S 0.05722 | 3.757548 | 0.15611 | 7.193431 | 0.38284 | 7.583018

TEMPERATURE COEFFICIENT.—Having now obtained the rate
of intake at chosen points on each curve, we can proceed to deter-
mine the quantitative effects of temperature on the rate of moisture
intake. First we must know the ratio of the velocity at 20° to that
of 5° C., and of the velocity at 35° to that at 20° C. These ratios
for the intake velocities presented in tables XI and XII are given im
table XIII.

In the earlier data, represented by table XI, if we take the
average velocity at 5° C. as unity, we have the comparative mean
velocities at 20 and 35°C. according to the ratio 1:2.05:2-05%
1.83=3.75. Since the temperature of intake in the last curve

1920] SHULL—SEEDS BF0

is 30° higher than the first, the mean value of Q,, will be obtained
by extracting the cube root of the final term, 3.75, which is 1.55.

In the later data, table XII, the mean value of Q,. is higher.
The final term of the ratio is 6.11, and its cube root 1.83. In both
cases the value falls between the coefficient of temperature .effects
on physical and on chemical processes, but in the last case it
approaches the van’t Hoff coefficient. These figures are com-
parable with the value of Q,, obtained by Brown and WorLEy
for barley, as they have been obtained in exactly the same manner:
The value of the temperature coefficient for Hordeum was 2.02.

BRowN and Wor -ey considered that the velocity of intake was
almost exactly an exponential function of the sr a teae If it is,

TABLE XIII
RATIOS OF INTAKE VELOCITIES (Xanthium)

"DATA TABLE XI : Data TABLE XII
INTAKE :

geet Velocity 20° Velocity 35° Velocity 20° Velocity 35°
Velocity 5° Velocity 20° Velocity 5° Velocity 20°

Pee Ree es, 1.88 1.72 2.39 1.81

S fe ay a Ce 1.92 1.75 2.81 1.96

SOO bees 1.97 1.80 3.47 2.32

5 apa oA 2 ae eae 2.08 1.83 ac7t: 2.47

fe gh ee ae 2.18 1.90 Q2 2.35

huge ah pew iee 2.29 1.96 4.73 2.45

Mean ratios 2.05 1.83 2.79 2.19

logarithms of the velocities plotted against the temperature must
lie in straight lines. They show in their second diagram such a
plot of the logarithms, and state that the course of the lines in the
diagram, in respect both of the straightness and of the agreement of
inclination, furnishes evidence of a most conclusive character that
the rate at which water is absorbed by barley seeds is an exponential
function of the temperature. They call attention to the rarity with
which physical properties show an exponential increase with rise in
temperature, and then propose that the change is chemical and
Probably involves a simplification of the water molecule, as
already stated.

The logarithms of the velocity of water intake by Xanthium
seeds have been plotted similarly in fig. 3. The curves plotted

380 BOTANICAL GAZETTE [May

above the zero line represent the velocities for the earlier Xanthium
data of table XI, while those below the zero line are from the
later data from table XII.

1 ve
| These curves will be dis-
1-4 cussed later.
ee

et

1-2 at SPLIT PEAS
1.0——+ > ee ed The split peas offered
. g special difficulties from the
ae es mathematical side, and no
-6 attempt is made to present
ss a complete account of the
rote es analysis of the data given
-2 in table VI. The variabil-

in ity of the data is much
ed greater than in the case of

1.8 | cockleburs. The absorp-
ee ve ate tion is fairly consistent
1-6 -— rai rer. during the first hour, or,
1.4 us - ff at high temperatures, dur-
us a a ing the first 15 or 20
1-2 rss a = fad minutes. After a certain
T8 oe rd Wel critical p tage has been
Be 8 A, reached, however, they
2-8 show a remarkable rise
z above the ideal curve in-

t
& (1s 96 45 30 35° roe by the first par

Fic. 3.—Logarithms of ve f the absorption. This

3.—Logarithms o ids Deity plotted against ee tak
about

temperatu i from table XI, critical percentage 1s

ure:

lower series a ‘table XU; Xanthium seeds. 20 per cent in the case of
the Tom Thumb variety,
about 23 per cent in the Canada Green field pea, and about 30
per cent for the Small Scotch Yellow commercial. The reasons
for the rise in the rate of absorption will be considered in the gen-

eral discussion.
As the Small Scotch Yellow gives us the longest period of
consistent intake I shall present here data for this variety only,

1920] SHULL—SEEDS 381

and only for that portion of the curves which precedes the rise
in rate.

Difficulties were encountered in choosing an enapiaseal formula
for the split pea data, owing partly no doubt to the fact that no
duplicate tests were run, and the only set of data showed rather
large irregularities at the beginning of the absorption. Curves
closely approximating the data beyond 5 minutes ran below the
point of origin. The one minute value ran quite too high in the
20 and 35° C. data, and somewhat too low in the 5° C. series. In
any case the constant c in the formula was so small that it was
thought best, after considering all possibilities, to run the com-

TABLE XIV
ALGEBRAIC CURVE FOR ABSORPTION DATA; SMALL ScorcH YELLOW SPLIT PEA

Tie ine 20° ae

(MIN-

YTES)| Low |Computed| High | Low |Computed| High | Low | Computed] High
I 79 t Sisteiesc tee 3.95 Ce ene 20 F597
1a RC 7.45 P20 FS. 905) 1s ae ie, a: 16.341 46.4840
10 FiCSOt 27 AS 10006 | 2 20. 2h eas ste, 26.47 | 26.54
te eae 15290) SOc 4 a: 24.93 | 25.00 | 33.65 ray eae eee es
Bites} sna ceeds bce he Deer L wie lobes ec bee ut eres 9.43 | 41.54
ro Pigg Beeoet tas 22.36 | 23048 [2309-1 783 BE a al es eee
Dray Ae ae vires GH Talc ah eel Poeieeci aes, (Oe Crete rt Gag or eM eee Break up}......
Bere ss es A030 | BeCOP Aol os a,
Pons! 30.89 F 20.07 16 a des. MOE ie a
PR eee Pee ee as ey a ge Oe ee a eae ee

Break up

puted curves through the point of origin, and omit that constant
altogether. The generalized formula then takes the form y=a log,
+1). |
The three formulae, for the 5, 20, and 35°C. curves for the
Small Scotch Yellow peas, with values of a and b substituted, are
as follows:
5° C.:y=30.13 login (0.148%+1)
20° C.: y= 34.58 logy (0.284x+1) i
35° C.:y=60.90 log. (0.172%+1)
Using these empirical formulae, we have secured a-fair agreement
between calculated and observed intake, not so close as in the
case of Xanthium, but much closer than is frequently obtained

382 BOTANICAL GAZETTE [May
in attempts to reduce biological phenomena to mathematical
expressions (see table XIV).

The velocity of intake at the same six percentages used for the
Xanthium seeds has been calculated from the tangents to the
curves. The velocity in percentage per minute, and the logarithms
of the velocities are shown in table XV

TABLE XV
WATER INTAKE IN SMALL ScotcH YELLOW SPLIT PEA
°o 20° 33°
INTAKE
PERCENTAGE Velocity in Velocity in Velocity in i
rcentage | Logs. velocity] percentage | Logs velocity] percentage | Logr velocity
per minute per minute | per minute
Siete Ere 1.32160 | 0.1211 3.05728 | 0.485335 | 3.76544 | 0.575827
5 dag eee I.09175 | 0.038122 2.58846 | 0.413041 3.42593 | 0.534779
YO ees 0.90188 | 1.955148 | 2.19152 | 0.340745 | 3.11692 | 0.493725
WIE LS 0.61546 | 1.7892 1.57091 | 0.196151 | 2.58002 411623
Y20,...... 42 1.623249 | 1.12605 | 0.051558 | 2.13562 | 0.329524
5 hea ee 0.28662 | 1.457306 | 0.80717 | 1.906965 | 1.76775 | 0.247421

The ratios of the intake velocities for the split peas were obtained
from the data of table XV, and are presented in table XVI.

TABLE XVI
RATIOS OF INTAKE VELOCITIES; SMALL ScotcH YELLOW
SPLIT PEAS
Velocity 20° Velocity 35°
ayate arpedee Velocity 5° Velocity 20
WN a uke pose wale t Sage 1.23
A drei Reape eas Serer an 2.47 £.32
5 deel Sac gens a Vera 2.43 1.42
b dal in Pee ee se bees 2. 85 1.64
O ag ata see aye er 2.68 1.90
PA eee es cas 2.82 2.19
Mean ratio. ..... 2.53 1.62

From the mean ratios we find that the value of Q,. in this case is
1.6, or just a little higher than the earlier determination for
Xanthium. Since the calculations in the case of split peas are
made from single equation curves, all passing through the point of

1920] SHULL—SEEDS 383

origin, they offer the best possible opportunity to study the ques-
tion of straight line plots of logarithms against temperature. These

are shown in fig. 4. Itis ,

out in such a way as to make ae
possible a comparison be- 1.6
tween this work and that
aoe se
y Fic. 4.—Logarithms of velocity plotted
‘nificance of the results. against temperature, split peas, table XV.

seen that they are decidedly ~~ +}
——
not straight lines. 4 FA —
Having now presentedin . A . CP gs
some detail the resultsof the ~~ AL wee wi
mat} tical analysisof the 9-0 oe A pa
: : ay OS TMG
data, which has been carried | 1.9 Ae al «

Discussion

There are several features of the work by Brown and WorLEY
which need to be considered in judging its value. Attention
' was called in the introduction to the rather rough method of
securing tangents, which, however, was quite skilfully used.
In view of the fact that the early phases of absorption were not
Studied by them, however, it is possible that the tangents they
obtained between the point of origin and the first intake data at
each temperature would not agree with those of a curve plotted at
close intervals. If the barley seeds were to show a large initial
intake, the curve would be thrown upward from the base, and the
succeeding portion of the curve would have a different course,
affecting the very portion of the curve where the tangents are
measured in determining intake velocities. It is this early part of
the curve which is important, for the tangents are measured for
that part of the curve between the origin and 25 per cent of intake.

The greatest disadvantage in the data supplied by Brown and
Wortey is the long time interval between observations, and espe-
cially the long first interval. Their first observations were taken
at 5-6 hours after the beginning of absorption. If I had waited
5 hours for the first observations in any of the work presented

384 BOTANICAL GAZETTE [MAY

in this paper, all of the tangents used in measuring intake velocities
would have fallen on that part of the curve between the point of
origin and the first reading, all of which is constructed from imagina-
tion, as an “ideal curve.” In the case of barley it is not so serious,
but it is only in the 3.8° curve that all of the tangents fall beyond
the first observation. ‘In their 21.1° curve the first observation
showed over g per cent of intake, from which it is seen that the
5 and 7.5 per cent tangents were measured on a “‘guess curve”’
between the origin and the first observation, and the 34.6° curve
is still less favorable; for in it the first observation shows
nearly 17 per cent of intake, so that 4 out of 6 tangents used were
measured on a curve constructed entirely without data. This
matter is vital to the whole theory they propose, for they had but
three points in plotting logarithms of velocities against tempera-
tures, and if one of the points is insecure no conclusions can be
drawn. The other two points are bound to be in a straight line.
In four cases out of six, the third point is not established by data,
and in two of the plotted logarithm-temperature curves, both the
second and the third points are derived from tangents whose
determination is insecure. The evidence offered, therefore, that
the velocity of intake is an exponential function of the temperature,
is not very convincing. In this work I have used short time inter-
vals to understand better the curve whose tangents were to be
_ measured. Our short intervals have the disadvantage that water
movement goes on in the seed during weighing which occurs fre-
quently. There is no intake during weighing, of course, but dis-
tribution of water already taken in continues. I have felt that
the advantages of the close intervals between weighings exceed
by far any disadvantage that might exist.

In the case of Xanthium, with a semipermeable coat, and in
split peas without the coat, I have found that the plotting of
logarithms of velocity against temperatures does not yield straight
lines. The nearest approach to straight lines is seen in the uppet
half of fig. 3, but even here there is a slight divergence, always in
the same direction. A somewhat greater divergence from straight
lines is seen in the lower half of fig. 3, and a very marked divergence
is seen in fig. 4, in the case of split peas. From the data I conclude

1920] SHULL—SEEDS 385

that plotting logs of velocities against temperatures will yield some
kind of a curve, but there are not enough data at hand to determine
anything as to the character of the curve. The general conclusion
to be drawn from this part of the work is that the evidence, as far
as it goes, is rather against the assumption that the velocity of
intake is an exponential function of the temperature.

Another point that deserves notice is the nature of the curves of
water intake. Brown and WorLEY called their curves paraboloid
and described them as running out toward a common asymptote.
The language, of course, must have been intended in a very loose
sense, for parabolic curves passing through a common point of
origin, as theirs do, could never have a common asymptote. It was
found impossible to fit a parabolic formula to the intake data pre-
sented, but from the figures given in tabular form (tables VII-X and
XIV) it is evident that the logarithmic curve y=a logy (6x+1)+c
may be made to fit the data very closely. Furthermore I have
taken the 3.8° barley data and attempted to fit to it both the
logarithmic and a hyperbolic equation made to pass through the
origin and the second and fourth values of their data. I have
found that the logarithmic equation fits much closer to their data
than the hyperbolic equation. The two sets of values and the
original data are given for comparison. The time and data
columns are from BRowN and WorLEY.

Time Data Prove oc (nonetolc)
§. 68 hours; 06 eis 2: 4.42 4.41 Sat
24:76 hours) (3 acs 11.82 11.82 11.82
£5.82 DOU ois Ck 18.52 18.49 17-99
72 28 bese 8, 23.42 8 ea 23.42
Op. 00 BOOM... ss 27.42 27.506 28.78
144-28 hours. 6 oe Ls: 34.02 33.89 38.99

The logarithmic equation used in this comparison is y=48.6
login (o.025x-+1), and the hyperbolic equation, y=0.2024

x?+112.988x.

Considering the closeness of agreement which is obtainable with
the logarithmic formula, it seems more reasonable to consider the
curves of water intake, even in the case of barley seeds, as logarith-
mic rather than hyperbolic.

386 BOTANICAL GAZETTE [MAY

If the velocity of absorption were an exponential function of
the temperature, the relation between temperature and the rate
of entry of water into the seeds might be expressed by an equation
of the form v=ae” in which @ is the temperature. As I have
obtained evidence somewhat adverse to the assumption that
velocity of absorption is an exponential function of the temperature,
this equation does not hold. Wherever the logarithmic formula
.y=a logy(bx+1)+¢ holds for the curves of absorption, the velocity
of intake may be represented by the formula »=ae~** in which @
is the percentage of water already absorbed. In other words, the
velocity of intake is approximately an inverse exponential function
of the total preceding absorption. It is not claimed that this is true
for all cases of absorption, but that it is just as true as the logarith-
mic equation used. Wherever that equation holds, the velocity
formula holds.

The chief interest centers in the temperature coefficient of
absorption. I have obtained coefficients ranging from 1.55 to
1.83 in Xanthium seeds, and 1.6 in split peas. These are all
above the temperature coefficient of physical changes, and below
that for chemical change. Brown and Worry obtained a
value above 2, and adopted the idea that absorption was

for their observations, they suggested that the semipermeable ~
seed coat of barley was involved in a special way, in its relation
to complex or simplified water molecules. They suggested the
possibility that the differential septum (semipermeable coat)
permits only hydrone to penetrate it, and that the temperature
rise increases the proportion of hydrone in solution. One of the
main difficulties in the way of accepting such a hypothesis as to
the relation of hydrone to semipermeable membranes, is its impli-,
cation that all semipermeable membranes should behave alike.
Xanthium and Hordeum both have semipermeable membranes,
and if the rate of water passage depended solely on the proportion
of hydrone, treatment of either seed should give the same results.

It is a notable fact, however, that semipermeable membranes are
always individualistic. Each kind has its own behavior, no two

1920] SHULL—SEEDS 387

kinds acting exactly alike. It would not be possible to accept
without modification any theory which assumes that differential
septa are alike in behavior. I do not mean to say that water is
not simplified in structure as it is warmed, nor that such a change
would not increase the rate of absorption, but it seems entirely
possible to account for the high temperature coefficients found in
absorption phenomena without the necessity of assuming such
a change, or making it the sole change involved in the process.
The substances of which the seeds are composed, membranes,
embryo, and storage products, are all largely colloidal. These
colloidal materials undoubtedly are modified in state of aggregation
by being subjected during wetting to low or high temperatures.
Higher temperatures usually increase dispersion and increase the
water-holding capacity of organic colloids, and lower temperatures
reverse the process. It does not seem possible that such changes
could be absent during absorption, and they must go far to explain
the differences in intake rates and the values of Q,., which stand
between those found for purely physical and purely chemical
processes. Absorption is a complex process, probably involving
both physical and chemical factors, and the values of Q,, may be
considered the resultant of the effects of temperature on both
classes of factors. The fact that we get about the same value for
Qo in absorption without a semipermeable coat as with such a
coat indicates that the membrane is not necessarily the rate deter-
mining factor.

DEnNy (2) has shown that membranes differ greatly in their |
power to transmit water. If the seed coat transmits water more
slowly than seed substance can absorb it, the transmission rate is
a limiting factor on the absorption rate. If the transmission power
of the coat exceeds the absorption power of the seed substance,
however, the latter determines the rate. Again, if seed coat,
embryo, and endosperm form a very non-homogeneous structure,
the absorption rate may be dominated first by one of the structures,
and later by the others in succession, giving peculiar absorption
curves, difficult to analyze mathematically.

It was noted that Xanthium seeds showed a very rapid initial
intake during a minute or less, after which the rate broke sharply to a

388 BOTANICAL GAZETTE [way

lower rate. Two explanations suggest themselves for this. The coat
may absorb water more readily than seed substance, and the initial
intake may represent the saturation of the seed coat, or the rapid
initial intake may be caused by the fact that at first the absorb-
ing substance and water are in direct contact, but after a short time
the water absorbed by the interior of the seed must penetrate a
layer of saturated substance before it can reach the actively absorb-
ing material. This outer saturated layer may offer resistance to
intake in the form of friction with the moving water. As this
layer becomes thicker and thicker all the time, it may tend more
and more to reduce the absorption rate. Changes in the velocity
of absorption due to such causes might be found in any case of
water intake.
Finally, something should be said about the rise in the intake
rate in split peas after a certain critical percentage of intake has
been reached. During absorption one can observe that the hemi-
spherical cotyledons become swollen first around the thin edge
where water is penetrating from both sides. Looking at the
flat side of the cotyledon, one can see that the edge has
become raised up, while the center remains as it was origi-
nally, and appears depressed. The flat side has become con-
cave. It seems evident that a band of dry material extends
across the middle of the cotyledon from the center of the spherical
side to the center of the flat side, and that imbibition forces at
work in the edge of the seed are pulling at this dry band. After.
the critical intake has been reached, the center of the flat side soon
swells out, and the concavity disappears. It is practically certain
that the seed substance actually cracks apart during this process,
leaving interior cavities that fill up with water. This idea is
strongly supported by unpublished data, collected by DupLEy J.
Pratt, who worked in the laboratory of the University of Kansas,
on the effects of acids and bases on the swelling of pea cotyledons.
He was able to detect clearly the formation of such cavities during
absorption, and some of them are of considerable size, as when
strong hydrates or acids cause excessive swelling. This breaking
up of the internal tissues of the cotyledon satisfactorily accounts
for the peculiarities observed in absorption curves in split peas.

1920] SHULL—SEEDS 389

It is my conviction, after a number of years of experience with
absorption phenomena, that absorption is a complex process
dependent on a number of factors, some of which may be external,
but many of which are internal. I have become convinced that
we should not expect a single formula or rate law to apply to
absorption in general. Each case of absorption is likely to present
a problem in itself, and to differ, slightly at least, from any other
case, because of both qualitative and quantitative differences in
the numerous factors determining absorption rates.

Summary

1. This paper deals with the quantitative influence of tempera-
ture on the velocity of moisture intake by certain seeds, chosen
for the presence and absence of semipermeable coats. Xanthium
pennsylvanicum Wallr. and commercial and garden peas were used,
the latter with coats removed.

2. The curves of water intake were found to be complex, but
can be represented by a logarithmic equation or series of equations
of the form y =a log,.(bx+1) +e.

3. The analysis of the data presented does not support the
theory of Brown and Wortey that the velocity of intake is an
exponential function of the temperature, but the velocity of intake
at any given moment in the seeds studied is approximately an
inverse exponential function of the amount of water previously
absorbed.

4. The mean value of Q,. in Xanthium seeds was in one instance

1.55, in another 1.83, and in split peas of the Small Scotch Yellow
variety 1.6.

5. These values do not indicate that eniee 3 is conditioned
by some single chemical change like simplification of water to
hydrone as the temperature rises, but are believed to indicate
that absorption at different temperatures involves both physical
and chemical changes.

6. The main chemical changes with rise of temperature are
believed to occur in the colloids of the seed, and semipermeability,
as such, is thought not to be an important factor in determining
the rate of water absorption.

390 BOTANICAL GAZETTE [MAY

7. The paper considers critically the methods and interpreta-
tion of the similar work of Brown and Wortry on Hordeum
seeds.

UNIVERSITY OF KENTUCKY
Lexincton, Ky.

LITERATURE CITED

1. Brown, A. J., and WortzEy, F. P., The influence of temperature on the
absorption of water by seeds of Hordeum vulgare in relation to the tempera-
ture coefficient of chemical change. Proc. Roy. Soc. London B 85:546-
553- 1912.

2. Denny, F. E., Permeability of certain plant membranes to water. Bor.
GAZ. 63:373-397- 1917.

3. SHULL, C. A., Semipermeability of seed coats. Bot. Gaz. 56:169-199.
1913.

, Measurement of the surface forces in soils. Bor. Gaz. 621-3 I.
1g16.

5. Sey Asi Rag isolation of types in the genus Xanthium. Bot.

Gaz. 50: 474-483. I915

'

PETIOLAR GLANDS IN THE PLUM?
M. J. DorSEY AND FREEMAN WEISS
(WITH PLATES XX, XXI)

True functional glands are present in the plum in three posi-
tions: on the leaf serrations, on the leaf base, and on the petiole.
In the peach, plum, and cherry, the petiolar glands have been
given a place of considerable taxonomic importance. In the
course of the fruit breeding work at the Minnesota Agricultural
Experiment Station, excellent material became available for a
study of the glands in the plum in certain hybrids and pure forms.
Since certain questions regarding their variation and morphology
appeared to be as yet open, the investigation reported herein was

egun.

In a historical review of the taxonomic use of the petiolar
glands in the stone fruits, GREGORY (3) showed that the earlier
writers had ignored these structures; while later pomologists had
made use of them in distinguishing major groups, as in the peach.
Other writers, however, questioned the taxonomic value of glands,
because of the variation observed in number, shape, and position.
From an extensive study of the leading varieties of the peach,
GrEGoRY concluded that on typical shoots the glands were con-
stant, and that in many cases their shape could serve to separate
groups of varieties. He arranged the better known peach varieties
under three types of glands, reniform, globose, and indistinctive,
but pointed out that mixed and transitional types occur.

Heprick and others (4) record the gland condition on the
petiole and leaf serrations in the descriptions of the principal
varieties of plums in New York. Similar data have been brought
together for cherries (HEDRICK et al. 5) and peaches (HEDRICK
et al. 6). In the latter work the statement is made that “no one
familiar with any considerable number of varieties of peaches

*Published with the approval of the Director as Paper no. 160 of the Journal
Series of the Minnesota Agricultural Experiment Station. The writers acknowledge
their indebtedness to Dr. C. O. RosENDAHL for criticism and suggestions, and to
Ernest Dorsry and James Gray for assistance in collecting and classifying material.

39t] ; [Botanical Gazette, vol. 69

392 BOTANICAL GAZETTE [MAY

would attach very great importance to glands in a system of
classification.”

On the whole, the tendency of later writers has been to attach
less significance to glands in classification than has been done by
earlier writers. In technical fruit descriptions, or in systematic
classifications, it is evident that the value of a character as a
distinguishing feature between forms depends largely upon its
constancy of expression. Consequently, a statistical analysis was
undertaken with the object of determining the number and dis-
position of glands in certain species and hybrids available.

Material

Data were first collected in 1914 in the F, generation of crosses
between Burbank (Prunus triflora) and Wolf (P. americana), and
Abundance (P. triflora) and Wolf. The gland condition was sub-
sequently (August 1916) obtained in an additional number of
species and interspecific hybrids. Single trees in each case of as
nearly uniform age and size as possible were selected, and 400
leaves, on all trees which bore this number, were taken at random
from vigorous 1-year shoots. By following this method of collec-
tion consistently on trees under fairly uniform growth conditions,
the data obtained for the different forms are as nearly comparable
as can be obtained under field culture.

There are a number of factors which influence gland develop-
ment. In general it may be stated that those conditions which
produce vigorous vegetative growth favor gland development,
since on old trees or on trees subjected to unfavorable growth
conditions, the petiolar glands become much reduced, some-
times even disappearing, although normally present in the varie-
ties. On the other hand, position has an influence on glandular
development. Leaves borne at the basal position on terminal
growth, on fruit spurs or thorns and also in flower buds, typically
bear no glands at all or have them less well developed than leaves
borne at other points.

The arrangement of the glands (that is, whether opposite or
alternate on the petiole or leaf) was not recorded. Glands occur
both in pairs and alternately, near together or widely separated,

1920] DORSEY & WEISS—PETIOLAR GLANDS

393
but since they vary independently on either side of the petiole,
their relative position appears to be only incidental.

Variation in gland position and number
In horticultural literature, glands have been described with
respect to color, type or shape, size, number, and position. In

TABLE I

SELECTED INSTANCES ILLUSTRATING METHOD OF RECORDING DATA AND SHOWING VARI-
ABILITY OF GLANDS (A) ON DIFFERENT LEAVES WITHIN A VARIETY, (B) WITH

CE TO POSITION ON PETIOLE OR LEAF BASE, (C)

DIFFERENT VARIETIES, AND (D) WITHIN SAME

WITH REFERENCE TO
VARIETY DURING DIFFERENT SEASONS.

No. BORNE ON ghia ar ake BuRBANK BurBANKX WOLF No. 9
Peti- L
ale eaf IQI4 IQ17 IQI4 1917 Igr4 IQI7
OO. errs ores I5 38 Io 45 44 52
Ob aa aa a 27 35 16 63 25 44
cit oy DU SR Ae ei ae 28 37 32 45 28 45
OF Foy Oa Be i Ses che oe ee : See OL a
SO ee a 34 40 6 8 25 a
Ey tet 20 33 8 29 63 48
Eo} ai. I 16 9 25 9 6
Ree et ee es ees wap es a On ae ee ee ess
COR rea, 219 188 67 65 I4I 161
pe Tas MS ier 39 10 45 47 49 5
a ee pe ee Fe Oa arate 33 18 I I
© re ease oe hs es es ee Bea hee aes ge ire ae na Cae ena
SB Oy ac oe ees II 2 55 20 8 4
ne le Sse Melty SB Maveiiine. 33 17 Bee Uae rep
Ble Dow cola Cl a a Oe a el ae ed
FO hs RES ae ens AE RE A Be Bat fem a5 oR ERA DENG ST
Ae ee Dg Pen ener 24 3 I I
Be oe aaa eae ee 9 sas Ua eee ME
PCO peerage as te es 2 yg Waar ace eres Romer a
Sl Ee ee se Pe ee Ce ee i* To hee se
Bee i a a I Me ales ou ee
ce ee i
at GPa nicaeee Baie Cages Fone Be neice, foc. os hey cao ies
— on
TOI. A: 401 919 505 525 437
cibnds on leaf .} 143 187 321 349 220 202

the plum the globose form is the prevailing type, and the true
reniform type is found so seldom that little attention has been
given to shape. The color of the mature glands in the plum is
dark brown; and since these studies of number and position were
made on mature leaves, color characters were also not recorded.

304 BOTANICAL GAZETTE Te [MAY

Data taken as to position and number were arranged in the
form illustrated in table I, in which each leaf is classified with
respect to the position and number of its glands. For instance,
in Burbank 67 leaves bore two glands on the petiole and none on :
the leaf in 1914, and in 1917, 65 leaves fell in this class. A number
of other varieties could have been included, but these were selected
as typical of the great variability encountered.

Table I shows that in number and position glands are e extremely
variable on different leaves within a variety, but that the range
of variability is fairly typical for each variety. The number of
glands borne on the petiole is greater than the number borne on
the leaf base, and while the number borne in each position is
considerably different from season to season, yet the grouping
opposite each class is quite similar in each variety in spite of the
fact that the 1917 data were taken from different trees, but of
the same clones, from those of 1914. Taking Burbank again as an
illustration of variability, it will be seen that some leaves have
no glands on either the petiole or leaf, while others bear as many
as five on the petiole and three on the leaf. If observations as to
gland condition made on a few leaves or herbarium specimens are
considered from the standpoint of the variation shown, it will be
evident that some caution must be exercised in classifying the
gland condition.

Referring to the variability of glands within the species, it
will be seen that a similar condition is found to that shown wi
varieties. A summary of the position and number of glands in
all the species investigated is presented in table II, in which the
gland condition is given for a total of 3477 leaves.

Four points are of interest in table II: (1) without ‘ee
there are more glands borne on the petiole than on the leaf base;
(2) when there is one gland present it may be borne either on the
leaf base or on the petiole; (3) when two glands are present, the
larger number is without exception borne on the petiole; and (4)
when more than two glands are present, without exception a
strikingly larger number occur on the petiole.

For the convenience of the reader the data presented in table
II, with the addition of data from certain interspecific hybrids,

DORSEY & WEISS—PETIOLAR GLANDS 305°

1920]

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NO ANYOd AAAWAN ANVIO AALLOAMSAA ONIMOHS NOILVOLISAANI AAAGNA SWAOT TIV NI SGNVIO JO NOILISOdSIC OL SV

Il GTAVL

Vivd 40 AYVWWNS

306 BOTANICAL GAZETTE [May

are rearranged in table III, to emphasize the modal class for gland
number on the petiole and on the leaf base. It will be seen in all
the combinations summarized therein that the mode for gland
number on the petiole (with only three exceptions). is two, and
that on the leaf base it is zero. In other words, the 2-o condition
shown in figs. 1 and 11 is typical in the plum. Thus it appears
that the glands in the plum are too variable, both in position and
number, for accurate statements concerning their disposition on

TABLE It

SUMMARY OF GLAND CONDITION IN ALL FORMS STUDIED, SHOWING MODAL CLASS OF GLANDS
_— ON PETIOLE AND LEAF B

&t Zp
. x q < Toraz |GLANDS BORNE ON PETIOLE| GLANDS BORNE ON LEAF
I
SPECIES OR CROSS Bae 3] wear
a a 8 = NUMBER
A Number | Mode| Mean |Number| Mode| Mean
Abundance - triflora)....... I 400 409 | 2 | 1.023 | 189 | © | 9-473
Burbank (P. triflora).......... I 400 913 | 2 | 2.285 | 333 | © | 0-833
olf (P. americana mollis)..... I 400 607 | 2 | 1.518 39 | © | 0.010
Paki et A be eee 38 | 15200 | 21956 | 2 | 1.440 | 9125 | O | O-
a eee ae 22 10406 | 2 | 1.300 | 5028 | o | 0.628
LU ISS ee ER ihee 8 6 ° 0.406 Oo | 0.242
P. Bessey “Sand ney le : stl ane DH a18 107 | 0 | 0.268
yk CRONE. 86s cy ee 6 800 | 3359| 2 | 1.866] 788] o | 0 438
P. Besseyi XP. pe
minert (Compass).......... I 400 428} 2 | t.e70 | 912] © [ese
ag CLOSES. Cee eee 8 1437 | 2019] 2 | 1.405] 514] O | 9-357
eevee is os I 400 707 | 2 | 1.768 | 242| © | 0-605
P. domestic oe Siew I 400 35.| 0 088 | 287 | o | 0.718
I 200 o | 0.455 | 112| © | 0.560
P. acne A Rat ranks Me) t 400 554 2 1.385 8 | o | 0.020
WON oe io cl I 200 | 438| 2 | 2.019 33 | 9° | 2-165

any other basis than that of a statistical analysis. Other char-
acteristics of glands, however, may be of distinctive value, and
gland disposition may be sufficiently different and characteristic
for a variety or species to be of taxonomic value. The outstanding
feature of the data on the disposition of glands is that the mode
for gland number on the petiole, with three exceptions, falls on two,
and that the mode for the number borne on the leaf base in every
instance is zero. This condition obtains notwithstanding the
great diversity in the forms under investigation, and even in the
three exceptions to a modal class of two on the petiole, the mode

1920] DORSEY & WEISS—PETIOLAR GLANDS 307

was zero. This is significant in view of the fact that these three
forms, P. americana, P. domestica (Shippers’ pride), and P. domes-
ticaX P. americana, showed the greatest suppression of the glands
of any of the forms included in this investigation. This condition
will be given even greater emphasis in view of the connection found
to exist between glands and the vascular system of the leaf.

Connection of petiolar glands with vascular system

With the status of the glands as to number and position shown
by the statistical analysis in mind, it now remains to be seen.
whether or not there is a basic cause for the predominance of the
2-0 frequency.

The leaf trace in the plum has three bundles of conducting
tissue at its departure from the vascular cylinder of the stem,
which cause three gaps in the woody cylinder. The central bundle
extends up the petiole, through the blade, and branches succes-
sively at the large lateral veins. The outer bundles give rise to
Strands which run along the upper side of the petiole, forming
pronounced ridges on either side. These strands run directly to the
petiolar glands, or to the large ones borne on the leaf base, and
terminate there. The term petiolar gland, therefore, will be used
in this connection to include both. The lateral strands are shown
in fig. 30, which was drawn from a young leaf, and they are equally
conspicuous whether the glands are borne on the leaf base or some
distance down on the petiole. Where there is more than one
gland on either side of the petiole, branches from the lateral strands
connect with them.

On the other hand, the glands of the leaf serrations have a
distinctly different vascular connection. Instead of being con-
nected by branches with the lateral strands, glands in this position
have their vascular connections with the central bundle through
the lateral veins. It appears, therefore, that on the basis of
differences in their vascular connections the petiolar glands and’
the glands borne on the serrations can be placed in two distinct
classes. Other considerations also support this view. The petiolar
glands are much larger than those on the serrations and may
Show differences in shape, such as the reniform or necked types,

398 BOTANICAL GAZETTE [May

which would readily differentiate them. Also under orchard con-
ditions the glands on the petiole may be active much later in the
season. ‘That there is no relation between the glands in the two
positions is further shown by the fact that in some species, as in
P. americana, glands are typically absent on the serrations but
present on the petiole or leaf base.

Glands which could not readily be classified as belonging to
either the leaf serrations or the petiole were not numerous, con-
sequently error from this cause has not entered to any appreciable
extent into the statistical classification. There was also little |
difficulty in determining whether glands were borne on the petiole
or leaf base, since in most cases there was no leaf tissue between
the glands and the base of the blade. When leaf tissue was so
present they were classed as being borne on the leaf base.

The question now arises as to whether the structure of glands
on the petiole is similar to that on the leaf base. GREGORY (3)
showed that glands borne on the petiole and leaf base in the peach
were true glands, the upper part being composed of long rec-
tangular cells rich in cytoplasm, and with large nuclei, while the
central part is made up of parenchyma cells characteristic of
glandular tissue, into which extend ramifications of conductive
‘tissue. The structure of the glands in the plum borne on both
the petiole and serrations has been examined on leaves just emer-
ging from the bud, and on mature leaves with vigorous active
glands, and is found to be similar to that reported by GREGORY 1n
the peach.

The similarity in structure between the glands borne on the
petiole and on the serrations led Grecory to suggest that the
former arose from the latter. Such an origin would imply that both
are of the same rank, and that the tissue of the leaf blade is more or
less indeterminate with that of the petiole, and would be in accord
with the condition of the petiolar glands in some species of willow,
notably Salix lucida (fig. 10), in which the glands are minute,
numerous, and crowded together at the leaf base, suggesting 4
proliferation of leaf tissue along the petiole. ;

From these considerations it appears that there is justification
for regarding the glands of the petiole, and the larger ones borne

1920] DORSEY & WEISS—PETIOLAR GLANDS 399

on the leaf base, as of the same structure but of different rank
from those borne on the serrations. This is in keeping with the
evidence presented in the statistical analysis in which the number
two figured so prominently, that is, two glands on the petiole and
none on the leaf base, or one in either position, or less frequently,
two on the leaf base. The points emphasized are of significance
from the standpoint of phylogeny, and will be given greater em-
phasis from that standpoint.

‘Phylogeny of leaf as ‘indicated by glands, vascular system,
stipules, and abscission layers

There are structures other than the glands whch are significant
from the standpoint of the ancestral type of leaf in Prunus and
related genera. Cook (1) called attention to a joint in the leaves
of Amygdalaceae ‘‘just above the insertion of the stipules,” and
States that the ‘‘basal section of the leaf below the joint”’ has a
separate abscission from that of the leaf proper. This ‘basal sec-
tion” is regarded as belonging to the leaf on the basis of the
attachment of the stipules to it, although the stipules themselves
absciss early, and hence ‘‘the persistence of the base of the leaf”
has been overlooked. Gorset (2) characterizes stipules as ‘“ap-
-pendages arising at the insertion of a leaf, attached either wholly
to the petiole or to the stem, or to both.”’ Srynotr and BAILEy
(12) regard the stipules as arising through the stimulus of the
growth of the lateral leaf trace, and although they are morphologi-
cally integral parts of the leaf, in some exstipulate families having
trilacunar nodes, they are represented by mere swellings opposite
the leaf trace. In some stipulate genera with opposite leaves, as
Viburnum, the stipules arise midway between the insertion of the
petioles, apparently directly from the stem. Cook also states that
in Texas this basal section in the peach may remain alive for a
year or two and then wither away; while in Maryland it lives
through the winter and separates in the spring, leaving a fresh |
green scar.

In most of the plums studied in this investigation, this structure
does not separate at all, but may be clearly observed (the petiole
scar with its three bundle scars, and the two stipule scars at its

* 400 BOTANICAL GAZETTE [MAY

sides) on 3-year or even 4-year-old wood. Some vestige of it
often remains a year or two longer, but usually after this time it
begins to slough off. :

It was not until some young trees of Amygdalus Davidiana,
which were making an extremely rapid spring growth, were
examined that the separation which Cook described was found.
Ordinarily it requires some effort to remove the dry scalelike
remnant left after the fall of the leaf, and usually there is more
or less tearing of the bark; but in the case of Amygdalus Davidiana
this structure separated easily and clearly when started with a
knife point. In many cases after the rapid spring growth it .
cracked and separated without any outside stimulus, and later a
large proportion fell as a result of further enlargement at the
node. The condition is represented in fig. 5, which shows the
separating scale, and fig. 31, which shows its structure in greater
detail.

Examination of rapidly growing shoots of other Prunus species
showed that a similar separation may take place, especially in
some of the P. Besseyi xP. triflora hybrids, although in no case
quite so sharply as in Amygdalus. At least a partial explanation
of the fact that the separation of the scar scale occurs in some
species of Prunus and not in others, can be made on the basis of
the character of the swelling of the node below the leaf insertion.
When it is straight in outline, it makes an acute angle with the
line of the shoot and terminates in the leaf scar along a narrow
ridge, as in Amygdalus (fig. s). The rapid growth in spring of
tissue underneath forces off the dead scale at the apex. If, how-
ever, the node is swollen, with a rounded profile, and the leaf scar
is well buttressed below, as in the extreme type shown in fig. 4,
the scale does not separate, and cannot be removed without tear-
ing the bark. In either case, whether separation is immediate
or delayed, it is only the shedding of dead tissue, just as bark is
shed, and is done without the aid of a definite abscission zone
(Loyp 9g), and consequently is not true abscission.

A search for corroborative evidence as to the nature of this
structure showed that in a number of genera it is not uncommon
for clean cut separation of a scar scale to occur when rapid growth

*

1920] DORSEY & WEISS—PETIOLAR GLANDS 401

begins. Some of the species which show the separation of the old
leaf scar more clearly even than Amygdalus are Shepherdia argentea,
Cornus stolonifera, Tilia americana, Rhamnus cathartica, and Celtis
occidentalis, the first two of which are illustrated in figs. 16 and
17. All of these have simple leaves and lack petiolar glands, and
Cornus and Shepherdia are exstipulate and have entire leaves,
which, according to Stnnott and BAILEY (11, 12), is an advanced
state of node and leaf morphology. Hence we must regard the
structure to which the stipules and petiole in Prunus are articu-
lated, not as an additional foliar element, but as an outgrowth
from the stem; and therefore abscission of this kind does not
necessarily indicate an additional foliar element. |

The manner of insertion and abscission of the stipules in the
plum furnishes additional evidence that the structure described
by Cook as a persistent leaf base is in reality a part of the stem,
and that the leaves of Amygdalaceae cannot therefore be jointed.

In some Rosaceous genera, as Potentilla and Rosa, the stipules
are adnate to the petiole, forming a somewhat sheathing base, and
fall with the leaf. In others, as Pyrus and Prunus, the stipules
are separate, or nearly separate, from the petiole, and absciss soon
after the buds unfold. In Prunus the stipules usually drop long
before the leaf, but occasionally they persist throughout the grow-
ing season, and even over winter, in vigorous, late growing branches
in which cold weather has stopped further growth. The point
of normal abscission is illustrated in fig. 32 (P. hortulana minert).
The stipules, like the petiole, separate at a definite abscission
layer at their base (figs. 1, 2). As Cook pointed out, the joint of
the latter lies above the stipules, that is, distally to them, although
since the abscission lines of the petiole and the stipules form a
sort of crescent with the points upward, a face view of the stem
shows the stipule scars above that of the petiole (figs. 31, 32).

The typical leaves of many stipulate genera of the Rosaceae
have stipules adnate to the petiole, forming a more or less sheathing
base. This condition is also to be found in the bud scales and the
scales transitional to leaves in Prunus. Morphologists regard bud
Scales as relatively primitive in structure, since they have not
Specialized to serve such varied functions as the leaves themselves. -

402 BOTANICAL GAZETTE [MAY

Accordingly, the bud scales of Prunus may be taken as an index
of the ancestral leaf type. A series of bud scales and scale leaves
grading into true leaves is shown in figs. 18-29, which were taken
from a young shoot of the Compass cherry (P. Besseyi xP. hor-
tulana mineri).

It may clearly be seen that in the outer scales the stipules are
represented by blunt lobes, as large as the central lobe which
represents the leaf blade. The inner scales show progressive
reduction in size of the lateral lobes and increase of the middle
one, accompanied by differentiation into stipules and lamina. It
will be noted, also, that there is progressive splitting of the stipules
from the petiole. .In the mature leaf of the plum this splitting
has progressed to the base of the petiole, so that leaf and stipules
have separate abscission, but from one originally continuous
abscission layer. Prunus avium, as represented by the Dyehouse
cherry, is at a somewhat intermediate stage. In the leaves near
the base of a shoot, the stipules are clearly adherent to the petiole,
while in the upper leaves they are separate, as in the plum. In
all these transitional bud scales separation from the axis is clearly
below the stipules, and there is no evidence of an abscission layer
above them cutting off the middle lobe or leaf blade (fig. 2); hence
the stipules in the plum must be regarded morphologically as
integral with the leaf base, although the course of development
separates them from the petiole in the mature leaf.

It remains to interpret the structure of the petiolar glands in
relation to a more primitive type of leaf. Their organization and
their occasional proliferation into leaflike outgrowths indicate that
they are reduced structures. This change from a glandular to 4
foliar structure was noted by Cook (1), who described the occur-
rence of “small oblong or spatulate leafy organs on the upper
part of the petiole, taking the place of the nectaries” in certain
varieties of apricots. A similar transformation has been observed
in Crataegus, as well as a number of species of Prunus, and in some
of the apricot hybrids at the Minnesota Experiment Station it is
of almost regular occurrence on vigorous shoots of young trees.
Some of the variations in this transformation are illustrated in
figs. 11-15. The view that the leaves of the Amygdalaceae are

1920] DORSEY & WEISS—PETIOLAR GLANDS 403

jointed, led Cook to conclude that the ancestral leaf type of this
group was compound, the nectaries representing ‘‘rudiments of
divisions of compound leaves.’’ It should be pointed out, however,
that if the modern plum leaf represents the terminal leaflet of an
originally compound leaf, the glands, representing reduced lateral
leaflets, should be found below the joint by which the terminal
leaflet is articulated to the rachis. It is obvious that being situated
on the petiole above the joint, they cannot represent lateral leaf-
lets of an ancestral pinnate form. Microscopic sections of the
petiole at the leaf base do not show an abscission layer subtending
the blade, and the presence of one is not indicated by the normal
manner of shedding the leaves. It may be safely concluded, there-
fore, that the leaf blade of the plum is not articulated to the
petiole, as in Citrus, Berberis, or Trifolium. Sometimes, however,
if there has been late growth in the fall and the leaves are immature
when the first frosts occur, the leaf axis may be broken anywhere
from the middle of the blade to the base of the petiole, although
most frequently at the juncture of the blade and petiole. In this
case the ‘twig enters the winter with a part or all of the petiole
adhering at each node, which, however, usually breaks off at the
point of normal abscission by spring. |

Glands, however, may represent divisions of an alternate
divided or pinnatifid leaf, such as Fragaria, Potentilla, and other
genera of the Rosaceae possess. The frequency of the occurrence
of two glands suggests a ternate leaf such as that of Fragaria.
The presence of additional glands may be accounted for on the
basis of branching of the lateral bundles, or by the common transi-
tion from ternate to quinquefoliate or pinnate leaves (LEwis
7,8). Some pinnate-leaved forms of Potentilla show reduction of
the lower divisions to smaller structures than are the leafy out-
growths in the position of glands in the apricot. Furthermore,
the lower divisions are frequently alternate instead of paired, as
is also the case with the petiolar glands in Prunus.

It will be recalled that in the plum the two lateral bundles
which connect with the glands terminate there, and do not con-
tribute extensively to the vascular system of the blade. In
ternate leaves which have three strands, the outer two provide the

404 BOTANICAL GAZETTE [MAY

vascular system of the lateral leaflets, and this is also frequently
the case when there are numerous lateral leaflets, as in pinnate
forms of Potenitilla.

On foliar evidence the connection of the stone fruits, whether
regarded as a tribe of the Rosaceae or as a separate family, with
the Potentilleae is quite direct. The nodal anatomy is the same
(StnNoTt and BarLey 12) and the steps in leaf evolution appear
to be: (1) reduction of the lateral leaflets of a ternate or pinnate-
divided leaf to petiolar glands; and (2) splitting of persistent
adnate stipules from the petiole. In this series Prunus avium,
with an extensive development of glands, both in number and
size, or the apricot with a frequent reversion to leafy structures in
_place of glands, would stand below Prunus americana with its
almost glandless petioles. Grecory (3) regarded the globose
gland as more primitive than the reniform, since when normally
glandless leaves produced glands, they were always of a globose
type. If, however, the trend is toward reduction of glands, the
. glandless petiole would be the highest type, and the globose con-
dition transitional between it and the reniform.

It has been customary to trace the connection of the drupes
with the more primitive Rosaceae through Spiraea (RYDBERG 10).
Considered on the basis of floral evidence alone, this seems, a logical
sequence, Spiraea being intermediate in form of receptacle and
number of carpels between Potentilla and Prunus. Sinnott and
BAILEY (12) have shown, however, that Spiraea is exstipulate
and possesses a unilacunar node, while all species of Prunus have
stipules and a trilacunar node. It would appear that forms with
stipules could not be derived from forms which lack them. The
relationship of the stone fruits to the true Rosaceae is probably
more direct, and on the basis of anatomy there is less reason for
separating them as a distinct family than for considering them 4
well defined and specialized tribe.

Summary
Examination of over 30,000 leaves belonging to 15 species and
interspecific hybrids of the plum shows that two glands typically
occur on the petiole, or less frequently on the leaf base.

1920] DORSEY & WEISS—PETIOLAR GLANDS 405

On the basis of vascular connections the glands on the petiole
or leaf base are of a different order of structure from those on the
leaf serrations.

The stipules in the plum are morphologically integral with the
leaf base, and separate from the stem by a common abscission
layer. A portion of the node bearing the leaf and stipule scars
is subsequently shed in some species of Prunus as in other woody
genera; but the portion thus shed is not an additional foliar

On the basis of nodal anatomy and the presence of reduced
structures, the ancestral type of leaf in the plum is considered to
be a ternate lobed or divided simple leaf, the petiole glands repre-
senting the suppressed lateral members. In floral structure and
nodal anatomy Prunus and related genera form a logical series
with the Potentilleae, and should be considered as a specialized
tribe of the Rosaceae.

AGRICULTURAL EXPERIMENT STATION
UNIVERSITY OF MINNESOTA

LITERATURE CITED

1. Cook, O. F., Jointed leaves of Amygdalus. Jour. Wash. Acad. Sci.
2:218—-220. 1912. :

2. GOEBEL, K., Organography of plants. Eng. trans. by Batrour, Oxford.
1905. Pp. 359-376.

3. Grecory, C. T., The taxonomic value and structure of the peach leaf
glands. N.Y. Agric. Exp. Sta. Bull. 365. pp. 183-222. figs. 2. 1915.

4. Heprick, U. P., et al., The plums of New York. Report N.Y. Agric.
Exp. Sta. 1910, ok 2. 1910.

, The cherries of New York. Report N. Y. Agric. Exp. Sta. 1914,

e:
vol. 2. 1914.
, The peaches of New York. Report N.Y. Agric. Exp. Sta. 1916,
vol. 2. 1916.
7. Lewis, F. i Bs development of pinnate leaves. Amer. Nat. 41:431-
441. figs. 4.
oA ae study of leaf development. Amer. Nat. 41:701-709.
figs. 15. 1907.
9. Lioyp, F. E., Abscission in Mirabilis Jalapa. Bot. GAz. 61:213-230.
pl. 1. 1916

10. RYDBERG, P. A., Monograph of the North American Potentilleae. Mem.
Dept. Bot. Columbia University.

406 BOTANICAL GAZETTE [MAY

11. Stnnott, E. W., The anatomy of the node as an “6 to classification of
angiosperms. Aries. Jour. Bot. 1: 303-322. pl. 4.

12. Smnnott, E. W., and Barzey, I. W. site amie on ate phylogeny of
the angiosperms. 3. Nodal anatomy and the morphology of stipules.
Amer. Jour. Bot. 1:441-453. pl. I. 1914.

EXPLANATION OF PLATES XX, XXI
PLATE XX
Fic. 1.—Section through node showing abscission zone by means of which
the leaf is shed; a, only abscission zone present
Fic. 2.—Showing continuous abscission zone (a) for stipule and petiole at
early stage of growth.
Fic. 3.—Dark line at base of stipule showing point of abscission; note
that . is distal to attachment of petiole. :
. 4.—Instance of extreme swelling in node below point of abscission
of lek in such instances scar scale is not she
Fic. 5.—Enlarged view of shedding of scar- teat (a) in Amygdalus David-
iana as result of early spring growth; shedding of this type occurs only when
contour of node is relatively flat.
Fics. 6-9.—Variation in gland position and number; types illustrated
are 2-0 (2 on petiole and o on leaf base), 1-0, 1-1, and o-1.
‘PLATE XXI
Fic. 10.—Leaf of Salix lucida showing glands similar to those of leaf

_serrations crowded at base.
Fics. 11-15.—Types of proliferation of petiolar glands into leafy out-
wths

gro .

Fic. 16.—Node of Shepherdia argentea showing shedding of scar scale
similar to Amygdalus.

Fic. 17.—A node of Cornus stolonifera showing same as 1

Fics. 18-28.—Bud scales and basal leaves from young oe of Dye-
house cherry, presenting series in separation of stipules from leaf blade.

Fic. 20. —Enlarged basal leaf illustrating venation of stipules and leaf
blade; note that veins of stipules arise as branches of lateral strands.

Fic. 30.—Petiole showing prominence of lateral bundles in young leaf.

Fic. 31.—Shedding of dead scar scale in Amygdalus Davidiana from which
stipules and petiole abscissed previous season

Fic. 32.—Node of young plum stem hiowike relation of line of abscission
in stipule and petiole.

BOTANICAL GAZETTE, LXIX

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BOTANICAL GAZETTE, LXIX

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DORSEY & WEISS on GLANDS

INHERITANCE OF ALEURONE COLOR IN MAIZE
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 265
MERLE C. COULTER

Interested in the pedagogical value of plant genetics, the
writer was impressed with the fact that the bulk of our knowledge.
comes from experiments with corn. An investigation was under-
taken, therefore, with no more definite object than to discover how
dependable some of these classic experiments actually are. During
three years of rather interrupted and limited investigation, this
undertaking, as might be expected, has been rewarded by numerous
results that have been interesting and suggestive, but by prac-
tically none that as yet can be regarded as conclusive. In view,
however, of the number of investigators, professional and amateur,
who are now interested in inheritance in corn, it is felt that a brief
statement of a few of the results may be useful.

Technique

The writer’s experiences in matters of manual technique will
undoubtedly be of interest to amateurs. The grosser mechanics
of corn crossing are simple and familiar. The difficulties are
mainly two: (1) to avoid exposing the silks to chance foreign
pollen at the time the cross is made, and (2) to insure full pollination,
and hence full ears. It is common practice to remove, totally or
partially, the bag which covers the silks when the pollen is applied.
This involves momentary exposure of the silks to chance for-
eign pollen, plenty of which is almost sure to be circulating in
the air. Thorough distribution of the applied pollen over the
silks is then attempted by shaking the bag in some way. In the
hands of an experienced operator this method is not only adequate
but rapid. When the writer attempted this, however, the results
were not satisfactory. Less than half the ears were fully pollinated,
and there were quite a number of cases in which about 5 or 6 grains
of foreign pollen had evidently been admitted. For the second
Season’s work, therefore, a simple mechanical device was employed,
407] [Botanical Gazette,vol. 69

408 BOTANICAL GAZETTE [MAY-

and this effectually solved the difficulties. This is a so-called
corn-pollinator, a description of which has already been pub-
lished.* Even in inexperienced hands this method will not only
insure full pollination, but will never admit foreign pollen. Its
drawback lies in the fact that it lengthens the process somewhat;
hence it is felt that this device may be recommended to all save
experienced operators, who are conducting extensive experiments.
Normal ratios

An attempt was made to discover how exactly certain complex
ratios might be predicted. Material was sought in which a number
of factors could interact to produce various but predictable (?)
ratios. Nothing was more suitable than the set of factors involved
in the inheritance of aleurone color in corn. These factors have
already assumed an important réle in pedagogy. R and C are

complementary factors, the presence of both being required for
_ the production of red aleurone, and P? is a supplementary factor
which changes red to purple (PRC is purple, pRC red, PrC white).
Other factors have been added to this set by East and EMERSON,
but they are not dealt with in this paper. The original stock
‘material was furnished by East, to whom the writer wishes to
express his appreciation.

Leaving out of consideration those well established cases in
which a 1:0 or 3:1 ratio is produced, it was found that the material,
as originally provided, could be manipulated to produce 8 different
ratios. Appropriate crosses were made, therefore, and of the result-
ing crop all ears containing 64 or more grains are considered in
the following summary.

I.—o:1:1 (no purple:50 per cent oe per cent colorless)
ratio predicted; from pprrCC XppRrCC and reciprocal. Eight
ears gave a total of o purple:559 red:659 white, or an average

* Bor. Gaz. 58:63. 1919.

* East and Hayes use the symbol P for this factor, while Emerson uses Pr for
what is probably the same factor.

East, E. M., and Hayes, H. K., Inheritance in maize. Conn. Agric. Exp. Sta.
Bull. no. 167. pp. 142. ee 25. IQtt.

Emerson, R. A., A fifth pair of factors, Aa, for aleurone color in maize, and its

relation to the Ce and Rr pairs. Cornell Univ. Agric. Exp. Sta. Mem. 16 pp. 231-289-
1918.

1920] COULTER—ALEURONE COLOR 409

ratio of 0:0.92:1.08. The extreme ratios on individual ears were
0:0.81:1.19 and 0:1.03:0.97. Conclusion: slight but chronic
excess of colorless grains.

IIl.—o:9:7 predicted; from ppRrCc selfed. Five ears gave
0:418:320, or an average ratio of 0:9.06:6.94. Extreme ratios
on individual ears, 0:8.77:7.23 and 0:9.45:6.55. Conclusion:
predictions fulfilled.

TIT.—o:3:5 predicted; from ppRrCcXpprrCc. Three ears
Save 0:260:430, or an average ratio of 0:3.01:4.99. Extreme
ratios on individual ears, 0:3.19:4.81 and 0:2.94:5.06. Con-
clusion: predictions fulfilled.

IV.—1:1:2 predicted; from pprrCCXPpRrCc. Only one
ear with over 64 grains obtained.

V.—9:9:14 predicted; from ppRrCcXPpRrCc. Four ears
Save 229:242:262, or an average ratio of 10.11:10.35:11.54.
Extreme ratios on individual ears, 10.14:12.69:9.17 and
6.51:9.83:15.55. Conclusion: decided but not chronic excess
of colored grains.

VI.—3:3:10 predicted; from ppRrCcXPprrCc and pprrCc X
PpRrCc. Eight ears gave 252:235:765, or an average ratio of
3-22:3.00:9.78. Extreme ratios on individual ears, 3.60:2.07:
10.33 and 4.42:3.58:8.00. Conclusions: predictions fairly well
fulfilled, considering smallness of population used.

VII.—9:3:20 predicted; from PprrCcXPpRrCc. Only one
ear obtained with over 64 grains.

VIII.—27:9:28 predicted; from PpRrCc selfed. Thirteen
€ars gave 1534:464:1560, or an average ratio of 27.59:8.35:28.07.

xtreme ratios from individual ears, 23.54:9.92:30.54 and
28.97:11.03:24.00, Conclusions: predictions well fulfilled; slight
tendency toward excess of purple at expense of red (as was regu-
larly the case except, strangely enough, in the two individual ears
cited under extreme ratios) may well be accounted for by improper
Classification, throwing a few deep red grains with the purple.

From this preliminary experiment the general conclusion was
drawn that ratios produced by the interaction of these three
factors were sufficiently distinct to be readily recognized in the
vast majority of cases. This was confirmed by later experience,

4Io . BOTANICAL GAZETTE [MAY

which included also several other types of ratios produced by these
same factors. Actually the only difficult distinction which was
encountered was between 9:9:14 and 3:3:2, for the former (V)
commonly showed a deficiency of colorless: grains. How per-
sistent and significant this deficiency is I will not venture to con-
clude from the limited data. Elsewhere recognition was easy so’
long as P, R, and C were the only factors dealt with.

Dominance

The literature is likely to leave one with the impression that
dominance is complete with this set of factors. Uncertain on
this matter, the writer wondered whether there was any hope of
distinguishing genotypes from superficial appearance. In other
words, was a grain with the formula ppRRCC a very dark red,
ppRrCC or ppRRCc a lighter red, and ppRrCc a still ligher red?
That such a thing might be possible was suggested by the following
observation. When individuals of the formula ppRRCC were |
selfed, they regularly produced ears on which all of the grains were
not only red but the same intensity of red. Obviously the grains
were all of the same (ppRRCC) genotype. Likewise, ppRrecX
pprrCC would produce ears on which only 50 per cent of the grains
were red, but always the same intensity of red. Here, also, all
the red grains would be of the same (ppRrCc) genotype. In
contrast with this were ears so produced that the colored grains
represented more than one genotype. It was common in suc
cases for quite a series of color intensities to appear. Whether these
different intensities to any degree represented the different geno-
types was an open question, but one that could be readily decided.

An ear was chosen which had been produced by ppRrCcX
PpRrCc. This particular ear was noteworthy in two respects.
In the first place, where it should have shown a 9:9:14 ratio
it actually gave 57:61:57. In the second place, an unusual
range of color intensities appeared. Now the g purples theoreti-
cally should have been distributed among the following genotypes:
t PpRRCC:2 PpRrCC:2 PpRRCc:4 PpRrCc; the g reds,
1ppRRCC : 2 ppRrCC : 2 ppRRCc:4 ppRrCc. The writer there-
fore classified the grains on the basis of color intensity, with some

1920] COULTER—ALEURONE COLOR 4Il

hope that four intensities of each color could be recognized. This
proved impossible, since the series of intensities was practically
continuous. At this point, therefore, I was forced to conclude
that at least genotypes could not be sharply separated on the
basis of color intensity. There yet remained the possibility,
however, that color intensity might to some degree depend on
genotype, the boundaries of the classes merely being obscured by
individual variation. With this in view the whole series of colored
grains was arbitrarily divided into several intensity classes, and
these classes were planted separately and selfed.

Class W, indicating colorless, gave six large ears, all of which,
of course, showed too per cent colorless grains.

Class R indicated faint red. This was the minimum color
intensity, and may best be described by saying that a casual glance
would discover no color in such grains. More careful scrutiny,
however, reveals an evenly distributed (not mottled or variegated)
but very faint aleurone color. In the original count of the parent
ear these grains had been classified as red. Only one ear was
obtained from this class, but that was very striking. Most of
its grains were colorless, but some were the same faint red as the
parent, and absolutely none were of any deeper intensity. Viewed
at a little distance, this ear would be said to contain too per cent
white grains.

Class R’, indicating light red, produced two ears, on which the
ratios were 0:42:31 and 0:88:54 respectively. Without hesitation
these were both diagnosed as 0:9:7 ratios, indicating. a ppRrCc
genotype.

Class R”’, indicating red, produced three ears, with sampctiie
ratios of 0:76:59, 0:176:63, and 0:24:8. One feels safe in calling
the first a 0:9:7 and the last two 0:3:1 ratios. The conclusion
from this is that ppRrCC or ppRRCc or both have a tendency
to produce a more intense aleurone color than does ppRrCc. The
question arises whether the appearance of one 0:9:7 ratio from
the red class was due to improper delimitation of the classes in the
first place, of which there was, of course, every possibility; or
whether it might have been due to inevitable overlapping of the
Classes owing to individual variation. I am in no position to

412 BOTANICAL GAZETTE [MAY

answer this, since I cannot say whether the particular grain which
gave the 0:9:7, although included in the red class, was noticeably
lighter than the other two. :

Class R’” indicated dark red (or purple ?). In the original count
these grains had been included with the red, but the intensity of
color was such that it demanded close scrutiny to distinguish
them from the purple. Four ears came from this class. Of these,
one gave 0:130:33, and the other three 0:200:0 (no exact count
was made of large homogeneous ears). The first was evidently
a 0:3:1, with an excess of red grains, while the others obviously
represented the ppRRCC genotype, the conclusions suggested being
similar to that of class R”’.

Class P indicated faint purple, with the same significance as
R for faint red. This class gave three ears, as follows:

Faint purple Faint red Colorless
53 36 141
5! I4 I4I

No attempt is made at present to attach any significance to these
counts. In fact, it is felt that such counts are rather untrust-
worthy, since the color is frequently so faint as to lie at the very
limit of visibility. Sufficient at present that not so much as a
single light purple or light red was produced on these ears; only the
faint color of the parents was regularly produced.

Class P’ indicated light purple, and gave three ears, 142:47:52;
34:14:40, and 13:1:12. The first is probably a 9:3:4 and the
others 27:9:28 ratios.

Class P” indicated dark purple, and gave one ear, 79: 34: 85
probably a 27:9:28 ratio with an excess of red.

The general conclusion from the preceding is that genotypes
may be distinguished, to a degree, on the basis of color intensity,
at least among red grains. One rather familiar with the material
should be able to pick out a given genotype in most cases, particu-
larly if he discarded intermediates, which the writer did not.

Returning now to the faint grains, one is confronted by three
possible explanations: (1) these are grains, properly colored, in
which an inhibitor tends to lessen materially the intensity of the

1920] COULTER—ALEURONE COLOR 413

color; (2) they are grains, properly colorless, in which there is some
partial substitute for the R or C (probably the latter, referred to
later) factors or both; (3) they represent something entirely
unrelated to the set of factors under discussion. That the second
is a likely explanation is suggested by three facts.

t. The count of the original parent ear showed a marked defi-
ciency of colorless grains. The faint red and faint purple grains
had, in that count, been classified as colored. If they were truly
colorless grains the original ear would have very closely approxi-
mated the predicted 9:9:14 ratio.

2. The nature of the original cross was such that every grain
must be Pp or pp, but never PP. Inbreeding, therefore, might
give ears with some red and no purple grains, but could never give
ears with some purple and no red grains. Actually that is what
occurred. This is, of course, merely negative evidence. Positive
confirmation, however, comes from a similar experiment conducted
with slightly different material. An ear produced by PpRrCc
selfed, which gave an ideal 27:9:28 ratio, was used as the basis of
an experiment similar to the preceding. The general results were
about the same and need not be discussed in full. Among the
purple grains, however, several produced ears which showed purple
and colorless, but no red grains, and one produced a full ear of
purple grains alone. This is to be expected from the fact that
genotypes including PP, although not present in the previous ear,
are present here. Such being the case, the behavior of the faint —
purple grains from this ear should prove significant. From that
class came the following four ears:

Light purple Faint purple Faint red Colorless
Some Some Many
° ' Some Some Many
° Some : ° Many
L 34 ° 4 ‘

These certainly suggest the presence of PP in the last two cases,
while Pp may be inferred for all the others. It is very likely that
the last ear represents the homozygous condition for faint purple,
whatever that may be, the color being present but —
in 4 grains.

414 BOTANICAL GAZETTE — [May

3. East and Hayes (Joc. cit.) describe in certain of their families
grains which they call particolored. Their description leaves
little doubt that the writer is dealing with the same phenomenon.
These authors carried their work far enough to assign the P(R)c
formula to these grains.

The tentative conclusion, therefore, may be reached that parti-
colored (faint) grains lack C but contain some partial substitute.
Just how this substitute is inherited is not clear as yet, but the
fact that it is heritable is undoubted. It is probable, although
not certain, that the same relationship between P and R as occurs
in the inheritance of the normal full color maintains itself also
under the particolored system.: It must also be noted that this
unknown substitute for C is by no means always effective in bring-
ing any distinguishable color; its powers of expression seem to
be limited by conditions, a matter which will be discussed later.

The question is now raised whether, in view of the possibility of
a complete series of color gradations, reliable counts of purple,
red, and colorless phenotypes can always be made. In answer
one may safely state that the phenotypes stand out sharply unless
particolored grains appear; the gap between light red and colorless
is a wide one. Particolored grains by no means appear in all cases;
the condition which brings them may or may not be present in the
germ plasm. When they do appear, they do so in considerable
numbers, so that a glance at the ear as a whole will determine
whether or not one has them to deal with. Thereby the investi-
gator is warned to focus sharply upon the boundary between light
colored and particolored, but even under the most practiced eye
_ some slight error is likely to creep in at this point.

An anomalous case

The possibility of at least partial substitution for the C factor
has been mentioned. We may be dealing with something of the
same sort in the following unusual case. East provided the writer
with an ear produced by PPRrcc x<pprrCC. The expectations
were obviously fulfilled, half of the grains being purple and the
other half colorless. The former, in the many crosses made,
regularly revealed the PpRrCc formula, which was expected; while

‘

1920] COULTER—ALEURONE COLOR 415

the latter, in all cases but one, revealed PprrCc. In this one case
the individual produced by this supposed PprrCc grain was selfed,
and gave a ratio of 46:0:36. This is a perfect 9:0:7 ratio, such as
would be produced by PPRrCc, but such a formula is out of the
question in view of the history behind the ear. The obvious but
heterodox suggestion is that some unusual condition is present,
which, together with both P and C, results in purple aleurone; while
with C alone it gives, not red, but colorless.

That this is a pathological case is suggested by two facts:
(1) practically all the grains on this ear had their pericarps split
irregularly, an unusual condition; (2) when planted, they germi-
nated very slowly (or not at all), giving 3-inch plants at the time
that all the neighboring rows had attained 3 or 4 feet; by harvest
time a few small tassels had just appeared, but no silks.

Mottling

Emerson (loc. cit.) has described the following situation in
certain of his families. When the R factor enters the cross with
the male parent only, a mottled aleurone results, while in all other
cases a solid aleurone color is produced. Thus, RRcc XrrCC gives
too per cent solid red; rrCC xRRcc gives too per cent mottled
red; RRCCXRRcc gives 100 per cent solid red; RrCC selfed
gives 50 per cent solid red, 25 per cent mottled red, and 25 per cent
colorless.

The writer wishes to express his appreciation to EMERSON ‘cn
providing material of the well known C tester and R tester. These
traces behaved with considerable regularity, for crosses between
them consistently yielded 100 per cent solid purple grains when
R tester was used as the male parent (PPRRccXPPrrCC), and
Ioo per cent mottled grains when C tester was used as the male
parent (PPrrCC X PPRRcc).

Splashed purple grains, recognized by East (Joc. cit.) in most, but
not all, of his families, were doubtless due to the same phenomenon.
In the particular material of East’s which was furnished, however,
nothing of the sort could be identified, even in the very numerous |
cases in.which the R factor came in with the male parent only. It
was felt, therefore, that crosses between the material from EMERSON

416 BOTANICAL GAZETTE [MAY

and that from East would prove interesting. Evidently the
former contains something which the latter lacks, and this some-
thing brings mottling instead of solid color, provided always the
R factor comes in with the male parent only. Such crosses should
help interpret this mottling, and should also reveal whether the
P, R, and C factors of these two investigators are identical. Four
crosses between C tester and East’s material will be considered,
with the families resulting therefrom.

TABLE I
CoLor RATIO MO?fTLING RATIO

Ear Cross : eres
Predicted Observed Predicted Observed
646 | PpRrCc selfed..... 27:9:28 66:22:69 62:14:81 2:1 51:25 58:18
645 | PpRrCc selfed..... 27:9:28 | 135:45:139 | 136:51:132 | 2:1 | 122:61 | 14439
631 pbRrCc selfed..... 27:9:28 | 141:47:147 | 157:36:142 | 2:1 | 129:64 | 122:7%
630 | PpRrCc selfed..... 27:9:28 | 177:60:184 | 181:55:185 | 2:1 | 157:79 | 159°77
642 | PpRrec selfed...... O:0:1 :0: 268 0501968. 4). 2.5 pe ie eee
643 | PpRrec selfed...... O:o0:! 0:0:461 O02400 1} cs cafe eee i Se
647 | PpRrCcXpprrCc...| 3:3:10 9:19:6 21:12:61 I:0 | 33:0 33-9
635 | PpRrCcXpprrCc...| 3:3:10 | 28:32:106 | 31:31:104 | 1:0 | 60:0 60:0
636 pRrCcXpprrCc...| 3:3:10 | 47:49:180 | §2:527172 | 1:0 | 96:0 96:0
644 RreeXpperCe 2.) 15226 8:8:49 9:9:47 20:1 18-0 18:0

652 | PpRrecXpprrCc ...| 1:1:6 IG:IQ: 115 | -20:212112 | 1:0 | 42:0 42
638 | PpRrCcXPPRrCc..| 9:0:7 88:0:68 74:10:72 a:t | 49:45 1. 52:3
49 | PPRrCcXPpRrCc..| 9:0:7 | 261:0:203 | 246:0:216 | 2:1 | 164:82 | 163:85
641 | PPRrCcXPpRrCc..| 9:0:7 | 159:0:123 | 156:0:126 | 2:1 | 104:52 | 100:50
640 | PPRrCcXPpRrCc..| 9:0:7 | 179:0:139 | 179:0:139 | 2:1 | 19:60 106:73
639 PRrCcXPpRrCc..| 9:0:7 | 314:0:234 | 313:0:235 | 2:1 | 209:104) 259:54

650 | PPRrCcXPpRrCc..| 9:0:7 II7:0:91 128:0:80 a:1 | 85:43 | 84
651 | PPRrCcXPpRrCc..| 9:0:7 | 224:0:174 | 239:0:159 | 2:1 | 259:80 | TOI 78

648 | PPRrCcXPpRree..| 3:0:5 63:0:104 63:0:104 | 2:1 | 42:21 | 44

I.—pprrCc (East) XPPRRce (C tester) gave 131:0:114 with
all the purple grains mottled, according to expectations. Obvi-
ously these mottled purple grains represented a PpRrCc formula,
the colorless PpRrCc. The number of this ear was 315, and its
further behavior is recorded in table I, in which the italicized
parent represents the immediate progeny of 315. Where mottling
ratios are recorded, the solid color member always precedes (2:1
means 2 solid color :1 mottled). Table I shows that predictions
on the color ratios are fulfilled in all cases, with the possible excep-
tion of ear 638; while mottling ratios are similarly according to
prediction with the possible (one feels like saying probable) excep-

1920] COULTER—ALEURONE COLOR 417

tion of ear 639. It is a very striking fact that where no mottling
is predicted (647, 635, 636, 644, 652) absolutely none appears.

II—PPRRcc (C tester) XppRrCc (East) gave 62:0:52 with
no mottling. Half the purple grains should have had the PpRRCc
formula, the other half PpRrCc; the white grains, half PpRRcc,
half PpRrcc. From the latter, two ears were selfed, both giving
0:0: 300.

A cross was made between an individual resulting from one of
the colorless grains as female parent, and ppRrCc as male parent.
Since the former could be either PpRRcc or PpRrcc, we must
consider both possibilities: (1) PpRRcc XppRrCc would give 1:1:2
and ne mottling (1:0); (2) PpRrcecXppRrCc would give 3:3:10
and a mottling ratio of 2:1. The actual ratios were 48:28:78 and
76:0, satisfying 1.

Two crosses were made between individuals resulting from two

of the colorless grains as male parents, and PPRrCc as female
parent. The two possibilities are: (1) PPRrCcxPpRRcc would
give t:0:1 and 1:1; (2) PPRrCcxPpRrcc would give 3:0:5 and
2:1. One of the resulting ears actually gave 115:0:134 and 78:37.
The color ratio might be either 1:0:1 or 3:0:5, but the mottling
ratio decides the case in favor of 1. The other ear gave 242:0:278
and 126:116. There might be a slight doubt about the color ratio,
but the mottling ratio decides in favor of 2.
_ Two other crosses in which 2:1 mottling ratios were predicted
gave 73:38 and 162:65 respectively. We may conclude that this
family also fulfils the predictions fairly well. It is interesting that
cases in which the color ratio may be a matter of some doubt may
sometimes be decided by reference to the mottling ratio.

I1I.—This family resulted from a cross reciprocal to the last,
or ppRrCc (East) XPPRRcc (C tester). This gave an ear con-
taining only 13 grains, so that the ratios are without significance.
The same possible genotypes are confronted as under II. One of
the colorless grains inbred gave, of course, 0:0:300. A single
individual, produced from one of the purple grains, was used as
male parent three times, once on its own silks and twice on PPRrCc.
If this individual had been PpRRCc, selfing should have given
9:3:4 and no mottling, while the cross indicated should have

418 BOTANICAL GAZETTE [MAY

given 3:0:1 and 1:1. If it had been PpRrCc, selfing should have
given 27:9:28 and 2:1, the cross 9:0:7 and 2:1. Actually selfing
gave 207:63:90 and 270:0, clearly indicating the former. In
the two cases of the cross indicated, the actual color ratios were
411:0:127 and 360:0:129. These are 3:0:1 ratios, and satisfy,
as before, the formula of PpRRCc for the male parent. The
mottling ratios in these cases, however, were respectively 278:133
and 235:125. Obviously, where it was felt that 1:1 mottling
ratios could be predicted with some certainty, the actual ratios
obtained were strikingly close to 2:1. The writer fully realizes
the care which must be exercised in classifying mottled grains.
These particular ears were not only shelled (as usual), but were
counted twice, using the same standards as proved satisfactory
elsewhere. One is forced to conclude that these additional data
represent an exceptional behavior, sufficiently decisive to be of some
real significance. :

IV.—pprrCC (East) XPPRRcc (C tester) gave unusual data.
It is unnecessary to give all of them; sufficient at present are the
mottling ratios obtained. Four ears resulted in which mottling
was to be expected in a 2:1 ratio. The actual ratios obtained were
155:0, 30:8, 151:3, and 177:3. Obviously the usual mottling
" situation is absent. The question arises whether the few so-called
mottled gtains were truly such. It is probable that they were not,
since there have been known to occur various types of anomalous
grains which may readily be confused with true mottling. Had
these grains occurred on ears known to contain true mottling, they
would have been included in that class. I feel justified, therefore,
in the tentative conclusions that (1) the P, R, and C factors of
East and EMERson are probably identical; (2) mottling is due to
a-heritable factor (or factors) which is present in Emerson’s ©
tester and absent in the material of East, and that this factor prob- _
ably behaves immediately as a dominant, no matter with which
parent it enters the cross. No attempt is made at present to explain
the 2:1 mottling ratios which appeared in two cases of family {il
instead of the expected 1:1. As for family IV, this situation may
be explained by assuming that not all of the C tester material was
3 homozygous for the presence of the mottling factor.

1920] COULTER—ALEURONE COLOR 419

The R tester material was similarly crossed with East’s
material. The color ratios obtained in five small families fully
satisfied the predictions. The mottling ratios obtained, however,
were quite different from those before, and may be summarized
as follows: (1) ten ears gave 100 per cent colorless aleurone, and,
of course, no mottling; (2) there were nine ears in which the R
factor, wherever present, had come in with the female parent; in
these, therefore, no mottling was to be expected; these gave a total
of 889 self-colored grains to 1 mottled; (3) cases in which a 2:1
mottling ratio might have been expected may be taken up separately
for the different families. Family I, produced by PpRrCc (East)
x PPrrCC (C tester), gave three such ears, with a total of 467 self-
colored: 5 mottled grains (1.06 per cent mottling; extremes
1.85 and 0.00 per cent). Family II gave four such ears with a
total of 333:30 (8.26 per cent; extremes 12.12 and 5.52 per cent).
Family III gave one such ear with 58:0. Family IV gave nine such
ears with a total of 1840:23 (1.23 per cent; extremes 2.22 and
©.00 per cent, one case). Family V gave three such ears with
638:51, or 7.40 per cent mottling; but that is not all. One of
these ears gave 263:10. The other two were identical with respect
to both their parents, both growing on the same plant. One of
them gave 237:41, the other 138:0.

One hesitates to draw any general conclusion from these data.
Certainly R tester does not contain that essential factor for mottling
which was present in C tester. In the event that Emerson’s C
tester and R tester were extracted fairly recently from the same
parent stock, the present situation might suggest that this unknown
mottling factor was an attribute of Emerson’s R factor itself, or
at least closely linked. This, however, would involve some
awkward, although not impossible, assumptions to explain the
behavior of mottling in those families produced by crosses of C tester
with East’s material; for, of course, the latter did not contain the
mottling factor. The situation would be somewhat simplified if
it were sweepingly assumed that the mottling which appeared in
these R tester families (just described) was not true mottling at all,
but just an imitation. True enough, mottling is at times fairly well
imitated, but these particular imitations were so like the genuine

420 BOTANICAL GAZETTE [May

article that the writer is very reluctant to discard them. A safe
tentative conclusion would be the following. The prime requisite
for mottling is that the R factor enter with the male parent only;
this perhaps is equivalent to saying ‘that the R factor be present
in the endosperm in just one out of three possible doses.”” Under
these circumstances mottling regularly occurs when there is also
present that condition which is possessed and transmitted by most
C tester individuals. A different condition, occurring in R tester,
favors mottling in a small percentage of the possible cases, while
the conditions present in East’s material permit of no mottling
under any circumstances. The critical data should, of course,
appear in the next generation.
Partial variability

The term “partial variability” has been used to indicate the
variation which may occur between different parts of a single plant
as regards any given character, without implying anything about
the mechanism which may explain this variation. It is therefore
preferable to “somatic segregation” for the present purpose.
Preliminary tests of the possibility of partial variability in corn
were conducted in two very simple and obvious ways. The first,
so far as it went, gave such decisive and orthodox results that it
may be summarized very briefly. With respect, at least, to the
P, R, and C factors, pollen from suckers that had been allowed to
develop was identical in crosses with that obtained from the main
plant. Ears developed on such suckers were, if present, so poorly
developed as to yield no adequate ratios; but ears produced on
suckers that had been allowed to develop abnormally, through
early removal of the main stem itself, gave the predicted ratios
in all cases. These results discouraged carrying out any large
scale test of this matter, at least as regards aleurone color. On the
other hand, a few sporadic cases suggest that such manipulation
might yield surprising results when applied to the inheritance of
plant color, and particularly chlorophyll. The other method was
to apply the same pollen to the silks of two of the ears on the same
individual, and to compare the ratios obtained. Such attempts
were frequently unsuccessful, owing to the inability of the plants

1920] COULTER—ALEURONE COLOR 421

to develop two sufficiently well filled ears’ under the handicap of
artificial pollination. Hence it was very common to get one full
ear, while the other contained so few grains as to be practically
worthless. This depends in part, of course, on the variety of
corn used.

The bulk of the data obtained was on starchy-sweet and yellow-
colorless ratios, and will be merely summarized at present: (1) the
ratios were virtually identical on both ears, and (2) any marked
deficiency of a given class on one ear always appeared in a strikingly

TABLE II

Ear Count Observed ratio | Predicted ratio
To ea ity haat 206:161 | 56.13:43.87 56.25:43.25
CGF oer. 203:158 56. 23:43.77 56. 25:43. 25
FOR ca ce. 242:81 94,00 525.36 75..00:25.00
ity dae rege 275:91 74.93:25-07 | 75.00:25.00
Ge. c i, 118:45 72.39:27.61 | 75.00:25.00
OSE SCG Coes 47:19 4E9T' 28.99 |: 75 ,00!45.00
OS2 UU ee bes 163354 75-57:24.43 75.00 5.00
OSG cate 33:14 70.21:19.88 | 75.00:25.00
ir Wee sense RR 108: 33 76.50:73-41 75.00:25.00
BOE, eek 62:15 79.48:20.58 | 75.00:25.00
OPO Fait es 138:80 63.30:36.70 | 75.00:25.00
Oa 276:94 74.59:25-.41 | 75-00:25.00
Ly Pe 43:42 50.58:49.42 50.00:50.00
BOO ia oe 25:25 50.00:50.00 50.00:50.90

similar degree on the other ear. Relative to some of the ratios
discussed earlier in this paper, representative data follow.

I. Colored-colorless ratios are markedly consistent for both
ears, as may be seen from table II. The only decided inconsistency
is between 670 and 678. There is little doubt that this incon-
sistency is real and significant, although it cannot at present be
interpreted. One feels, however, like regarding this as an isolated
exception.

II. Purple-red ratios are also about as consistent as could be
expected (table III). Probably the only significant case is 682-680.
Although the converse has been well demonstrated for other

422 BOTANICAL GAZETTE [MAY

ratios, it is altogether probable that such apparent deficiencies of
red in a purple-red ratio, instead of being due merely to chance, are
not only characteristic of given individuals, but heritable to some

TABLE Ut
Ear Count Observed ratio Predicted ratio
HOG oes se 155751 95.24:26,.96 | 75§,00:25.00
Caan eae se 152:51 74..39:25.61 75-00: 25.00
oo SE 182:60 975.20:24.80 | 75.00:25.00
907. ys 204:68 75.00:25.00 75.00: 25.00
OSs ee. 89:29 75.42:24.25 75 .00:25.00
pOGG Se ko, 38:8 80.85:19.15 | 75.00:25.00
O80 cs as 152737 80.98:19.02 75,.00:25.00
OBS oe 29:4 87.87:12.13 75.00: 25.00
O98 ene a. 101:37 73-19:26.81 75.00: 25.00
ay LR oeones a 212:64 76.81:23.19 | 75.00:25.00
Loy ae ge ae one 52:10 80.64:19.36 75-00:25.00
BI8e rk has 76:32 79.37:29.63 | 75-00:25.00
TABLE IV
Ear Count Observed ratio
O08 20274 98.06:1,04
CON ye ree. OT 99.51:0.49
WOR ae 24273 O8.77:1523
POPC ye 272:6 97-84:2.16
ho OBR ek 106:12 89.83:10.67
ne eG De 42°55 89.37:10.63
ae a ee 15479 94.48:5.52
Oe 29:4 87.87:12.13
Gye Oe ey 58:4 g1.91:8.09
S72 oe 84:24 7 79 28,43
Ok 130:0 100,.00:0.00
O78. 235241 _ 85.14:14.86
ad

degree. It must be realized, however, that such deficiencies of
red are probably apparent rather than real; improper classification
may throw dark red grains with purple, but it may well be that the
border line is thus obscured through some heritable tendency.

1920] COULTER—ALEURONE COLOR © 423

IIT. If one is to regard true mottling as limited to those cases
in which the character appears in all the grains which receive R
from the male parent only, that is, descendants of C tester, then,
unfortunately, no data are at hand on comparative mottling ratios
in two ears with the same parents. Such data, however, are
available from descendants of R tester, where mottling (or pseudo
mottling, as it may prove to be) appeared in relatively small
percentages, as shown in table IV. The discrepancies apparent »
in table IV may be taken to indicate that the supposed mottling
-of the R tester line is altogether sporadic and without genetic sig-
nificance. Even though that may be so, the surprising case of
670-678 is probably worthy of further investigation.

IV. Among the progeny of the faint colored grains only two.
poor examples of this sort are available, as may be seen in table V.

TABLE V

Count
Ear OBSERVED RATIO
Faint: Colorless

SOG. 3 So oe 177460 26.98:73.02
SOR erik 3 26: 104 20.00: 80.00
cy aa a aaer 0:42 ©.00: 100.00
a : Rasa wera rne 9:16 36.00:64.00

It is highly probable that the occurrence of these faint grains is
sufficiently limited by local conditions so that discrepancies between
two such ears will prove common. This is also suggested by the
results of a test which need only be briefly mentioned at present.
It is expected that the numerical value of any ratio, which is
affected only by matters Mendelian, will conform with predictions
based on the laws of chance. With equal certainty the laws of
chance indicate that, where a 1 colored:1 colorless ratio appears,
we will not find many long strings of colored grains lying together
in the same row. Actually we may expect that the colored grains
will be scattered within the rows of the ear in such a way that there
will be, speaking relatively, n groups of 1 colored grain each,
n/2 groups of 2, n/4 groups of 3, etc. These values will differ, of
- Course, with the ratios themselves. Thus, in a 3 colored: 1 colorless,

424 BOTANICAL GAZETTE [MAY

there will be n groups of 1 colorless, n/4 groups of 2, n/16 groups
of 3, etc.; while, for the colored grains, there will be n groups of 1,
3n
4
be calculated for any ratio, although they frequently must be
carried to several decimals. Such a test was applied to numerous
types of ratios, and also, for purposes of control, to the tossing of
coins (singly or in groups, depending on the ratio). The purpose
of the test was to discover whether any of the characters under
consideration were determined or limited by local conditions within
the ear. Preliminary tests of this sort showed that starchy-sweet
and colored-colorless ratios depended only on laws of chance. When
the test was applied to the self-colored-mottled ratios of the
C tester progeny, the laws of chance were fairly well satisfied,
but, undoubtedly, to a less degree than in the other cases. Such
slight nonconformity as occurred, however, might well have been
accounted for by difficulties in classification. Tests applied to
the mottling of the R tester progeny were not thought to be sig-
nificant, owing to the very small percentages of the mottled grains
appearing. With the particolored grains, however, very decisive
results were obtained, indicating clearly that local conditions on
the cob affect the appearance of this character. Thus in ears on
which less than ro per cent of the grains were particolored, the
majority of the total number of such grains was made up of a few ~
groups of 4 or 5 each. This is particularly interesting, since it has
been demonstrated that this condition is heritable. The puzzle
will probably be solved by finding that local conditions on the ear
do not determine, but merely limit, the appearance of the parti-
colored condition. It is expected that some, but not all, of the
seemingly quite colorless grains from these ears will perpetuate the
particolored tendency.

groups of 2, A groups of 3, etc. The exact values can easily

Summary
1. The use of the corn-pollinator is recommended to amateur
investigators.
2. The P(Pr), R, and C factors for aleurone color, variously
combined, gave predictable and readily distinguished ratios.

1920] COULTER—ALEURONE COLOR 425

3. In many cases the exact genotype, with reference to the R
and C factors, can be distinguished by superficial appearance.

4. The particolored grains of East and Hayes were identified.
In these some partial substitute enables the P and R factors to
express themselves, even in the absence of C. This substitute is
heritable, but its effectiveness is limited by local conditions in
different parts of the ear or of the plant as a whole.

5. Mottling (Emerson), which occurs when the R factor comes
in with the male parent only, is conditioned by the presence of a
heritable factor or factors. This factor occurs in the C tester
family, and is dominant in crosses with families which do not show
mottling. The R tester family seems to contain a different factor,
which produces apparent mottling only in a small percentage of the
expectations.

UNIVERSITY oF CHICAGO

BULBILS OF LYCOPODIUM LUCIDULUM
R. WILSON SMITH
(WITH TWENTY-ONE FIGURES)

It is well known that certain species of Lycopodium belonging
to that subdivision of the genus which is characterized by the non-
strobilar arrangement and slight differentiation of the sporophylls
produce organs of vegetative reproduction known as bulbils or
gemmae. These organs are of a peculiar type, so unlike anything
else in the plant kingdom that the question of their morphological
nature is a very puzzling one. Various opinions have been held.
They have been interpreted as equivalent to sporangia, to lateral
branches in the axils of leaves, to lateral branches without support-
ing leaves, to reduced branches resulting from dichotomy of the
stem apex and gradually displaced, and to the bulblets of certain
ferns and monocotyledons.

We owe the first accurate account of the development of the
bulbils to HeGreLmarer (4). He corrected the view previously
held that they originate in the axils of preexisting leaves, and
showed that they take the place of leaves in the phyllotactic
spiral. He could find no means of distinguishing very young
leaves and bulbils in longitudinal sections; and a view of the apex
of the plant showed a difference only when the larger size indicated
that a bulbil was beginning to develop.

STRASBURGER (10) gave a short description of the bulbils,
differing from HEGELMATER’s in some respects. In the following
year, after further investigation (11), he confirmed the interpreta-
tion of HEGELMAIER in every detail but one; he thought leaves
and bulbils differ somewhat in their mode of development. By
special manipulation of the stem tips, he selected for study those
tips on which young bulbils were present. In these young bulbils,
when viewed in longitudinal section, he thought he could detect
a middle apical group of two cells in the dermatogen. This account
does not contradict that of HEGELMAIER, for STRASBURGER really
found no difference between leaves and bulbils until the latter
Botanical Gazette, vol. 69] [426

1920] SMITH—BULBILS OF LYCOPODIUM 427

were distinguishable by their greater size. My observations on
this feature agree with HEGELMAIER’s. I have not been able, in
longitudinal sections, to distinguish a young bulbil from a young
leaf until it is recognizable by the beginning of an apical meristem
at its tip. STRASBURGER discussed the homology of the bulbil
with considerable care, and after considering the possible explana-
tions concluded that all the facts of development and histology
are best combined in the supposition that the bulbil represents
the survival of an original dichotomy (“‘eine einst dichotomischen
Ursprung’’). :

Much the same interpretation is given by CAMPBELL (1), who
says the bulbils “‘are formed apparently in the axils of somewhat
modified leaves... . . The axillary origin of the bulbils is only
apparent; they are really, so far as can be determined, similar in
origin to ordinary branches and formed without any relation to
the leaves.”

GOEBEL (3) considered the bulbils from the point of view of
their adaptations rather than their homology. Although dis-
claiming any attempt to solve the latter, he brought forward some
pertinent objections to current morphological explanations, and
concluded that in their most important features the bulbils of
Lycopodium are not unlike the bulblets of certain species of Allium
and Lilium.

The present investigation is an attempt to help solve the problem
of the bulbils by’ means of modern technique and serial sections
which were not available to the earlier investigators. Only L.
lucidulum has been studied, suitable material of other species not
being obtainable. STRASBURGER, however, found that there is a
great similarity in the bulbils of the six species which he compared,
and it is probable therefore that the following account with only
minor changes will hold good for all.

Description of bulbils

Two parts must be distinguished in the bulbil: the base which
remains attached to the stem of the plant for many years and does
not store up nutriment; and the distal part, or bulbil proper, which
is heavily laden with starch grains, and which, when mature,

428 BOTANICAL GAZETTE [MAY

separates from the base and readily gives rise to a new plant.
Between the two parts is a narrow neck which breaks easily when
the bulbil is ripe. The young bulbil has a small apical meristem
_atits tip, and as it grows produces decussate pairs of protuberances,
which in their relation to the bulbil axis resemble foliar organs,
but in maturity differ more or less from typical leaves. The
base has three pairs of these and the bulbil proper about six.
From the bulbil primordium there arise, as described by HEGEL-
MAIER from external appearances, first a pair of small leaves,
laterally situated, but soon displaced toward the stem apex; then
from the growing point between these a median pair, and soon
after them another lateral pair, not displaced. The median pair,
especially its abaxial member, is much the largest. This larger

Fics. 1~4.—Fig. 1, side view of bulbil base; X3; fig. 2, bulbil and base from upper
side; X3; fig. 3, bulbil proper from lower side; 2.5; leaves numbered in order of
appearance; 2b, “supporting” leaf; fig. 4, cross-section of tip of bulbil; leaves
numbered in order of appearance; X10.

outer leaf becomes the so-called “supporting” or ‘“‘cover’’ leaf of
the bulbil (figs. 1, 2). HeGELMATER was unable to decide whether
the further axis of the bulbil is the direct continuation of the
primordium, and the supporting leaf therefore truly lateral, or
whether the supporting leaf is the direct continuation of the
primordium, and the bulbil proper therefore an outgrowth and
truly lateral.

The first leaves of the bulbil proper are dorsal and ventral;
the second pair, which are lateral in origin, gradually turn their
upper edges outward and assume a dorsiventral relation; the thir
pair are median, long, and narrow (figs. 2, 3). These three
pairs of leaves are fleshy, and the leaves of the second pair are
also much modified in form. The remaining leaves of the bulbil

1920] SMITH—BULBILS OF LYCOPODIUM 429

are small and closely arranged about the growing point (fig. 4).
The axis of the bulbil proper develops endogenously two small
rootlets, which remain imbedded in the fleshy leaves until the
germination of the bulbil, when they push out into the soil.

Anatomy of stem apex and bulbils

L. lucidulum has only one mode of branching, namely, by
dichotomy of the apex. The growing point of the stem tip is broad
and flat, or slightly raised in the center, and is surmounted and
protected by the more rapidly lengthening leaves. In Lycopodium
there seems to be a relation between the form of the growing
point and the rate of growth. Slow growers, such as L. lucidulum
and L. Selago, have the apex as described (fig. 6); while rapid

Fics. 5—8.—Fig. 5, tangential section of bulbil: r; es f2, roots; 5, fleshy leaves;
X5; fig. 6, apex of stem: sp, young sporangium; X38; fig. 7, beginning of dichotomy
of stem in longitudinal section; 38; fig. 8, more es stage of same; X 23.

growers, such as L. clavatum, L. annotinum, and L. alopecuroides,
have the apex conoid in form and considerably in advance of the
youngest leaves. Before the apex branches it becomes wider
(there is considerable variation in the width of the growing point
‘without any apparent relation to branching). The initial cells of
the middle region now cease to grow and multiply, while those
on either side continue their activity (fig. 7). Soon the two grow-
ing points, separated by a cleft, begin putting forth leaves on all
sides (fig. 8). In longitudinal section it can be seen that the
central cylinder has divided into equal strands, and the two apices

are similar in all respects.

430 ' BOTANICAL GAZETTE [MAY

In cross-sections the equality of the two branches is just as
apparent. Fig. 9 shows a section of the central cylinder below a
dichotomy at a distance of about half a year’s growth from the
two tips. The central part of the cylinder is filled with immature
tissue, which can be distinguished approximately into xylem and
phloem areas. The shaded areas represent fully differentiated
xylem made up on the outer side of protoxylem tracheids, and on
the inner side of larger metaxylem elements. As differentiation
proceeds in this species, the metaxylem portions meet in the
middle of the cylinder and become more or less continuous, and the -
phloem occupies the indentations or bays between the xylem
strands. Surrounding the cylinder there is a clearly marked
endodermal sheath in the form of an irregular layer of cells, only
the inner contiguous walls of wh‘ch are thickened at this stage of

Fics. g—11.—Cross-sections of central cylinder of forking stem, xylem areas
shaded; small cross-hatched areas indicate leaf traces; X52.

development. In fig. 11 the whole sheath is shown, but in figs.
9 and 10 only the thickened cutinized walls are to be seen. As
the dichotomy proceeds the xylem strands change position but
little, the sheath from opposite sides pushing inward until the
division into two similar cylinders is complete. In this mode
of branching no branch gaps of any kind are formed in the sheath
or xylem or phloem. The length of stem between figs. 9 and
10 was 0.65 mm.; and between figs. 10 and 11 it was o.5 mm.
It will be noted that there are eight xylem strands in fig. 9, and
that in each of the two branches there are five. The new strands
are not formed by a division of old ones, but arise de novo out of
meristematic tissue. The beginnings of these strands may be
seen in fig. ro.

As shown by Jones (5), the protoxylem strands in Lycopodium
are constant neither in number, shape, nor position. New strands

1920] SMITH—BULBILS OF LYCOPODIUM 431

may arise either by branching of preexisting strands, or from the
meristem. I have also found that a strand when traced upward
may gradually diminish in size and ultimately disappear. In the
stem of which figs. 9, 10, and 11 are sections, the leaves were 9-
ranked, and this ranking continues in both the branches, not-
withstanding the reduction of protoxylem strands from nine to five.
As shown many years ago by CRAMER (2) and HEGELMAIER (4),
there is no relation between the number of orthostichies and the
number of xylem strands. The leaf traces of Lycopodium, so far
as they have been investigated, are mesarch in structure (7, 8).
They are so in L. lucidulum. The trace separates very gradually

Fics. 12-15.—Fig. 12, tangential section of young bulbil: 1, first pair, 3, third
pair of lateral leaves; fig. 13, radial section of bulbil rather older than fig. 12; 2,
first pair of median leaves; 4, first leaves of bulbil proper; 38; fig. 14, longitudinal
section of stem tip and young bulbil: 2b, “supporting” leaf; /t, leaf trace; bi, bulbil
trace; X23; fig. 15, longitudinal section of older bulbil, leaves numbered in order
of appearance; r, root tip; ro.

from the protoxylem of the central cylinder, traverses the peri-
cycle for a short distance, and then pierces the endodermis, after
first pushing it out into the form of a little pocket (figs. 10, 11).
The separation of the leaf trace causes no gap or disturbance in
the central cylinder. Immediately above and below the point of
exit the sheath closes. The leaf trace at first consists only of
spiral tracheids, but later is surrounded by deeply staining cells,
presumably phloem.

The vascular strand of the bulbil does not at all resemble that
of a branch. It is a single strand, similar in every way to a leaf

432 BOTANICAL. GAZETTE [MAY

trace in its relation to the central cylinder and its passage through
the cortex (fig 14). Not until it reaches the outer part of the cortex
or the decurrent base of the bulbil does it exhibit any essential devi-
~ ation from a leaf trace. Here it widens into a narrow tangential
band of cells, and presently gives off laterally two small traces to |
the first leaves of the bulbil (fig. 12). The middle part continues
and presently widens into a radial band whose outer portions be-
come the traces of the second pair of leaves (figs. 13, 15), and so
on until four pairs of traces have separated from it. ‘These facts
make it clear that the “supporting” leaf is undoubtedly a lateral
organ. In the bulbil proper in connection with the appearance of

LR a
eg FDO

16

Fics. 16, 17.—Fig. 16, cross-section of vascular bundle of bulbil where first root
is given off; 320; fig. 17, cross-section of bundles of bulbil and root below origin of
root: b, bulbil bundle; 7, root bundle; 320.

the first root a much greater change occurs. In a young bulbil,
even before the vascular tissues are differentiated, the tip of this
root is outlined as a mass of deeply staining meristematic cells.
A second and smaller root develops nearer the tip of the bulbil

(fig. 5). Both of these roots connect with the vascular strand of
~ the bulbil on its adaxial side and, turning downward and laterally,
remain imbedded in the parenchyma and separated from it by
slime and crowded tissue.

Fig. 16 shows the junction of the root cylinder and the axis
of the bulbil, and fig. 17 is a section below this. In both of these
it can be seen that the bulbil axis is still essentially a leaf trace,
but above the junction of root and axis all resemblance to a leaf
trace is lost. The arrangement of the tracheids is somewhat like

1920] SMITH—BULBILS OF LYCOPODIUM 433

that of a root, but much more irregular. Sometimes it is distinctly
diarch (fig. 18), more commonly it is horseshoe-shaped, and some-
times almost a complete ring, often with a few tracheids in the
center (fig. 19). Surrounding the whole xylem area there are one
or two irregular layers of cells, probably a pericycle, and outside
these an indistinct sheath (this feature is shown only in fig. 16).
This irregular arrangement continues until the fifth and sixth
pairs of leaf traces are given off and also the second root. Above
that the tissues are still meristematic in the ripe bulbil. The
bulbil, like the leaves, is well supplied with stomata, and photo-
synthesis proceeds actively. The cause of the accumulation of
starch in the bulbil proper and not in the base seems to lie in the
absence of phloem in the neck of the bulbil. Here the cells are

Fics. 18, 19.—Cross-sections of bundle above origin of first root; <320

entirely wanting which elsewhere in the bulbil surround the xylem
strand, and which I have regarded as phloem, although the sieve
plates have not been identified. The detachment of the bulbil
proper is brought about by a disorganization, apparently a gelatini-
zation, of the walls of the xylem cells in the neck.

When a ripe bulbil is kept on damp soil it soon germinates.
Both roots penetrate the soil and branch repeatedly, and from the
tip of the bulbil a slender stem is put forth. On this stem the new
leaves, although scattered, are from the first arranged spirally.
JONEs (5) traced the development of the vascular cylinder in the
young plants growing from bulbils of L. Selago and L. serratum,
and concluded that the original simple bundle becomes successively
diarch, triarch, etc., by division of the xylem. My observations
on L. lucidulum do not agree with this conclusion. I find, in
agreement with JONES, that the young stem at its attachment with

434 BOTANICAL GAZETTE [MAY

a

the bulbil is diarch, having two masses of xylem with one phloem
mass between, but followed up for nearly an inch, it never be-
comes triarch. The xylem becomes horseshoe- or ring-shaped,
much as in figs. 17 and 19, changing constantly, and there is no
hint as to how the multiprotoxylic condition of the adult stem
arises. The irregularity and continual change in the xylem of
these young stems are comparable to the conditions described by
Miss WIGGLESWORTH (12) in young Lycopodium sporophytes
growing from gametophytes.

HEGELMAIER’s statement that the bulbils replace leaves in the
phyllotaxy is confirmed by an examination of the relation of bulbil
and leaf traces. On following these back in cross-sections to their
junctions with the xylem strands of the central cylinder, the
bulbil traces are found in close succession. In many cases they
represent successive leaves; in other cases a leaf trace stands be-
tween two bulbil traces; but in every case examined the bulbil
traces all fell within a single leaf spiral.

Conclusions

_ 1. The bulbil is not the homologue of a branch, since it has
a simple vascular strand with mesarch concentric arrangement;
whereas branches have a vascular system with complex exarch
radial arrangement. Furthermore, it is not a reduced dichotomy
or the equivalent of the bulblets of Lilium or Allium.

2. It is not the homologue of a sporangium, for the reason,
among others, that it receives a prominent vascular strand, a
feature which is lacking in the sporangia of all Lycopodiales.

3. It is a transformed leaf, retaining the position, dorsiventrality,
and in great measure the vascular strand of a leaf. It may perhaps
be homologized with the bulblet of a fern produced so early in the
history of the leaf bearing it that the latter exhibits the leaf
character only while inside the cortex of the stem.

Further observations on the bulbils and habits of L. lucidulum

In the literature of the subject, I do not find any recognition of
the periodicity of the bulbils. In L. lucidulum they are quite as
responsive to season as the sporangia. The latter begin to form

1920] SMITH—BULBILS OF LYCOPODIUM 435

in autumn in preparation for the next year, and continue to form
when growth is renewed in the spring. Then, beginning some time
in June, for more than two months the apex develops a succession of
sterile leaves, in the midst of which two to four bulbils may make
their appearance, always near each other and on one side of the stem,
on that side of a branch which is farthest from the other branch.
The primordia of the bulbils increase rapidly in size, pointing
vertically upward at first like the young leaves, and thén gradually
becoming horizontal. They reach maturity in September. Since
the bulbils are formed but once a year and their bases are persistent,
it follows that they furnish a means of measuring the annual
increment of growth in length. There are other but less accu-
Tate means of estimating a year’s growth, by the old sporangia
whose walls do not completely disappear for several years, and
also by a difference in the length of sporophylls and sterile leaves.
The annual growth in plants bearing bulbils can be determined
quite easily for the last ten or twelve years, and in some cases
even for twenty years. It is surprisingly small, averaging about
One inch.

The possibility of determining the age of any given part of the
Stem leads to some interesting observations. For instance, it can
be shown that the metaxylem matures very slowly, not being fully
differentiated until well into the second year. The cortical zones,
characteristic of most Lycopodium stems, are not differentiated
until the third year. It is also possible to calculate the frequency
of dichotomy of the stems. The commonest interval between
successive dichotomies is four years, but intervals of two, three,
five, and six years also occur frequently. I have never found a
stem branching in two consecutive years.

Like several other species, L. lucidulum has the old stem
horizontal and rooted, and the young and greener stem upright.
By means of the bulbil bases it is clearly shown that the upright
part is six or seven years old. Observations from year to year
show that the plants, although adding annually one inch to their
length, maintain the same average height. Each year a part
of the erect stem, equaling a year’s growth, becomes curved
and finally horizontal. Fig. 20 represents the situation in four

436

successive years.

BOTANICAL GAZETTE [MAY

Decapitated plants are not killed, but, having

no means of renewing the apical meristem, they cease to grow or

successive yéars.

divide. Fig. 21 represents such a decapitated
stem in three successive years, the upright por-
tion shortened each year by the equivalent of a
year’s growth. Whether such a stem will finally
become altogether horizontal, I do not yet know,
nor have I yet been able to discover the cause of
the regular change in direction from upright to
horizontal. Observations in the field seem to
show that root contraction is not the determining
cause (stem tips decapitated in 1915 were found to
be dead in the summer of 19109).

Some interesting data can also be gathered in
regard to the behavior of the roots. These, as
in many other species of Lycopodium whose

tips are erect or sloping (6, 7, 9), do not pass
straight out through the cortex, but turn downward. In L. Selago
ese roots “arising at the apex pass obliquely, then directly
down through the middle cortex and only appear at the outside
beneath the soil’? (6). The same description is true of L. luci-
dulum, except that the roots do not originate at the apex, but
begin. at some distance behind the apex; how far behind is
not clear. They rarely form within the first year’s growth.
Apparently they increase in number in the older parts of the
erect stem; but as small roots might easily be overlooked in
freehand sections, I am not quite certain that new roots may
form in parts of the stem as old as five or six years. These
roots, in the upright part of the stem, remain small, usually less
than 6mm. in length.’ As they do not emerge to the outside
until in a part of the stem at least six or seven years old, it is
evident that they must be in a dormant or slowly growing condition
within the cortex for as many as two to five years. The downward
growth in the cortex is not very great, the distance between the
junction with the central cylinder and the point of emergence to
the outside varying from 6 to1s mm. Reaching the soil, they
grow rapidly, quickly reaching a length of several inches.

1920] SMITH—BULBILS OF LYCOPODIUM 437

Summary
The origin and vascular bundles of branches, leaves, and
bulbils are described, and the conclusion is reached that the bulbil
is comparable to a leaf rather than to a branch.

2. The accumulation of starch in the bulbil proper is ascribed
to the absence of phloem in the narrow neck joining it to the base,
and the detachment of the ripe bulbil to the disorganization of the
xylem walls in this region.

. The rate of growth is estimated from the persistent bases
of the bulbils, and observations are made on the habits of the
plant.

McMaster Unrversiry

Toronto, CANADA

LITERATURE CITED

- CAMPBELL, D. H., Mosses and ferns. London and New York. 1895.

- CRAMER, C., Ptesscnnieisiogache Untersuchungen (NAGELI and

_CRAMER) 3:1855; cited by C. E. Jones.

3- GOEBEL, K., Organographie der Pflanzen. Jena.

4. HEGELMATER, F., Zur Morphologie der Gattung Mote Bot. Zeit.
30:775-779, 780-8or, 805-819, 821-833, 837-851. 1872.

5. Jones, C. E., The morphology and anatomy of the stem of = genus
Tiycabadinas: Trans. Linn. Soc. London. II. Bot. 7:15-35. pis.2. 1905.

6. SAxeLBy, E. Mary, The origin of the roots in Lycopodium pial Ann.
Botany 22:21-53. pls. 2. 1908.

7- SEWARD, A. C., Fossil slant, vol. 2. 1910.

8. hia E. W., On Leas: setae in Lycopodium. Bot. Gaz.
48:138-145. pl. I. 190

9. SToKEy, Arma G., The pets of Lycopodium pithyoides. Bot. Gaz.
44:57-63. pls. 2. 1907.

10. STRASBURGER, E., Die Coniferen und die Gnetaceen. 1872.

, Einige Bemerckungen iiber Lycopodiaceen. Bot. Zeit. 31:81-95,

Q7-I10, 115-119. 1873.

. WIGGLESWorTH, GRACE, The young sporophyte of Lycopodium compla-

natum and L. clavatum. Ann. Botany 21:211-234. pls. 2. 1907.

oH

al
wv

TENDRILS OF SMILAX’
AGNES ARBER
(WITH PLATE XXII)

The nature of the tendrils of Smilax has excited perhaps more
controversy than almost any other problem arising out of the normal
vegetative morphology of flowering plants. It is unnecessary to
deal here in detail with the voluminous literature which has grown
up about the subject, since this task has been excellently performed
by Doin (4), who himself holds the opinion that the tendrils are
trichome structures, an opinion which does not seem to the writer
to be well founded. It will suffice to group together the various
_alternative views which he has enumerated, and to attempt to
test them, from the standpoint of the phyllode theory (1), by a
study of a typical species, Smilax herbacea L. (fig. 1). The views
which different authors have promulgated may be considered as
follows, under five heads:

1. That the Smilax tendrils are metamorphosed stipules, or
outgrowths of the apical region of the leaf-sheath.

Both these possibilities seem to be excluded by the fact that
the tendrils arise from the petiole, immediately above the sheath,
it is true, but entirely disconnected from it both externally and as
regards their vascular system.

2. That the Smilax tendrils represent a bipartite ligule, each
tendril being a demi-ligule.

This alternative is ruled out because, as Giiick (5) and DoMIN
(4) have shown, there is occasionally a definite ligule in addition
to the tendrils. It is also discounted for the same reasons that
make the first view untenable.

3. That the Smilax tendrils are either metamorphosed leaflets,
segments, or lobes of a compound leaf, or lateral free nerves whic
become detached before the others.

grant from the Dixon Fund of the University of London. The writer as to
; rial t

ie
the Curator of the Cambridge Botanic Sei
Botanical Gazette, vol. 69] {438

1920] ARBER—TENDRILS 439

If any of these related alternatives held good, we should expect
to find the vascular structure of the tendril showing some affinity
with the vascular structure of the midrib or lateral veins of the
“lamina” of the Smilax leaf. The midrib and lateral veins of the
blade, however, are each characterized by an arc of bundles (fig. 4),
while the tendrils have an irregular closed ring (fig. 3 B).

4. That the Smilax tendrils are metamorphosed trichomes or
emergences.

The high development of the vascular system of the tendrils
seems to make it impossible to accept this theory. The emergences
on the stem of Smilax itself, which on this view must be homol-
ogous with the tendrils, are non-vascular, as are the paired glands
at the base of the leaf of Tamus communis L., whose position at
first glance suggests a comparison with the tendrils of Smilax.

5. That the tendrils of Smilax represent ‘‘un double prolonge-
ment latéral des éléments cellulo-vasculaires du pétiole.”

This view, which was suggested by Cios (2) more than half a
century ago, and has been more recently supported by Grtick (5),
seems to contain the germ of the true explanation, although, in the
form in which CLos enunciates it, it is essentially descriptive rather
than morphological. The writer wishes to propose a related but
more comprehensive view, which interprets each of the tendrils of
Smilax as equivalent in morphological value to the petiole, and as
having originated through a dédoublement or chorisis of that organ.

An analogy may perhaps be suggested with the stamen pha-
langes of Hypericum Elodes Huds., which sometimes consist of three
members, and which very probably have arisen by secondary
chorisis of an ancestral single stamen. A closer analogy is indicated
by Queva’s (7) comparison between the anatomy and insertion
of the tendrils of Smilax and the stalks of the leaflets of certain
Dioscoreaceae with compound leaves. It seems by no means
impossible that, in this family, the compound character of the leaf
may also be due to chorisis of the petiole giving rise to three equiva-
lent organs."

* The writer hopes to deal in a ~ paper with the genera subject of _eompoane

leaves among monocotyledons, and t y have played
in their origin.

440 BOTANICAL GAZETTE [MAY

It is unnecessary to follow the relations of the vascular system
of the petiole and tendril of Smilax in detail, since this has already
been done by Qureva. The general equivalence of the vascular
structure in these organs is shown in fig. 3B. It may perhaps be
objected that the occurrence of a ring of bundles in the Smilax
tendril, instead of being an indication of homology with the petiole,
may merely represent that skeletal arrangement which best enables
the tendril to perform its special function. The weight of this
criticism, however, is lessened when we realize that in the leaf
tendrils of another member of the Liliaceae (Gloriosa superba L.,
fig. 6), which approach radial symmetry in their external form quite
as closely as do the tendrils of Smilax, the plan of the vascular
system remains purely dorsiventral, although the amount of xylem
increases considerably in passing from the lamina to the-tendril
(figs. 7, 8). The leaf tendrils of Fritillaria verticillata Ledebour,
and of Polygonatum cirrhifolium Royle, resemble that of Gloriosa
in structure.

According to the phyllode theory advocated by the writer (1),
the blade of Smilax is not equivalent to the lamina of a dicotyledon,
but is merely a ‘“‘pseudo-lamina”’ representing an expansion of the
upper region of the petiole. The thickened tip (fig. 5 ap) which
characterizes the blade of some members of the genus, for example
S. mauritanica Poir., is possibly the last relic of the unexpanded
petiolar apex. Each tendril on this interpretation is equivalent
to the petiole+pseudo-lamina. On the other hand, in Gloriosa the
leaf seems to be reduced to the sheath or leaf-base alone, the tendril
representing the specialized tip of this leaf-base.

Petiolar tendrils, with the blade entirely, or almost entirely,
aborted, are not unknown among dicotyledons, as, for example, the
first leaves of a species of Tropaeolum described by DARWIN (3)-
In connection with Smilax, it is perhaps significant that a tendency
to torsion of the petiole or leaf-base is by no means rare among
monocotyledons. Cases are known, for instance, in the Com-
melinaceae, Amaryllidaceae, Zingiberaceae, and Gramineae, as
well as in the Liliaceae, to which Smilax belongs (6). In most
of these instances the torsion, even in the extremest examples,
merely leads to resupination of the leaf; but in Gloriosa this power

1920] ARBER—TENDRILS 441

of twisting of a region which, although now apical, seems in reality
to be part of the leaf-base, has been utilized in tendril formation.
It is interesting that Polygonatum includes both species with twisted
leaves and also species whose leaves have tendril apices resembling
those of Gloriosa. Similarly in Smilax the torsion capacity of the
petiole seems to have fulfilled itself on 1 specialized lines in the pro-
duction of a climbing organ.

It may be noted in passing that the blade of Smilax often con-
forms to a shape which is one of the most characteristic among
those adopted by the pseudo-lamina of monocotyledons, its outline
being entire and more or less ovate, with a base which is cordate
or somewhat sagittate (fig. 1). Forms of this type, as has been
pointed out in a previous paper (1), are not only known in
the Liliaceae, but recur in the Alismaceae, Pontederiaceae, Dios-
coreaceae, Araceae, and Orchidaceae. This list may now be
increased by the addition of Cyanastrum cordifolium Oliver, of the
Haemodoraceae; and certain species of Commelina among the
Commelinaceae.

To the writer, the whole organization of the leaf of Smilax
is best explained according to the phyllode theory, and the inter-
pretation suggested has been reached from this standpoint. At the
same time, however; the view here propounded, of the origin of the
tendrils of this genus through chorisis of the petiole, in no way
depends upon this general theory. There is nothing to prevent
its independent acceptance by those who do not share the conviction
that the leaves of monocotyledons are invariably of the nature of
petiolar or leaf-base phyllodes.

Summary
In this paper the conflicting views hitherto held regarding the
nature of the tendrils of Smilax are briefly considered, and it is
concluded, on grounds of anatomy and external morphology, that
these tendrils are equivalent to the petiole in morphological value,
and have arisen through chorisis or dédoublement of that organ.

Ba.Lrour LABORATORY
CAMBRIDGE, ENGLAND

442 BOTANICAL GAZETTE [May

LITERATURE CITED

1. ARBER, AGNES, The phyllode theory of the monocotyledonous leaf, with
special reference to anatomical sichopeuain ipa Botany 32:465-501. 1918.

2. Cros, D., Les vrilles des Smilax ni p Bull. Soc. Bot. France
4: 984-087. 1857. -

3- Darwin, C., The movements and habits of climbing plants. London.
Paee

MIN, K., Morphologische und phylogenetische Studien iiber die ae
Pare Ann. Jard. Bot. Buitenzorg 24:117-326. pls. 23-33.

5. Gritcxk, H., Die Stipulargebilde der Monokotyledonen. VVerhandl, eee
hist.-Med. Vanes Heidelberg. N.F. 7:1-06. pls. 1-5. 1901.

6. Hanscrre, A., Phyllobiologie: Leipzig. 1903.

7. QuEvA, C., Recherches sur l’anatomie de l’appareil végétatif des Taccacées
et des Dioscorées. Mém. Soc. Sci. Lille. pp. 457. pis. 18. 18094.

EXPLANATION OF PLATE XXII

In all sections xylem is indicated in black, and phloem and undifferentiated
bundles in white.

Fic. 1.—Smilax herbacea L.: single leaf showing sheath (s), tendrils (¢),
and petiole (p); .

Fic. 2.—Smilax herbacea L.: A, transverse section of very young lamina
and accompanying tendrils; Sasttie tissue too young to be well differentiated ;
petiole as yet sindeveiped: B, actual attachment of tendrils; these sections
illustrate large size of tendrils relative to lamina in embryonic stage; X31
circa.

Fic. 3.—Smilax herbacea L.: transverse sections of mature leaf; A, through
leaf sheath; B, through petiole and tendrils, showing relative orientation of
organs; X1Iog circa.

Fic. 4.—Smilax herbacea L.: transverse rail ae to base of lamina
passing through midrib (mr) and main lateral (ml) ; 9 cir

Fic. 5.—Smilax mauritanica Poir.: A, pen lamin with ‘thickened apex
(ap); x3; B, transverse section through apex; X19

Fic. 6.—Gloriosa superba L.: leaf with apical oe .

Fic. 7.—Gloriosa superba L.: transverse section ee ee lateral
veins fused so that only midrib ge 2 laterals show; X31 Cir

Fic. 8.—Gloriosa superba L.: transverse sections of sidiick leaf showing
transition from apex of limb (A) ‘a a of tendril (C); 31 circa.

PLATE XXII

BOTANICAL GAZETTE, LXIX

SMI\ILAX
tendrils

lamina~

oe 8

Embry ome Leaf.

GLORIOSA

Tendril

SMILAX

Go

Base 4 tendril

S MILAX

Base of Lamina

Axdel. mr. rae Apex of oe g
GLORIOSA

ARBER on SMILAX

CURRENT LITERATURE

MINOR NOTICES

Engler’s Syllabus.—The seventh edition of Engler’s Sy/labus' had marked
a great progress beyond the sixth; 135 pages of text had been added and the
usefulness of the book was greatly increased by the introduction of illustrations.
No such radical changes were made in favor of the eighth edition, which
appeared in the summer of 1919. The number of illustrations remained the
same, although some were replaced by new ones, and the text was only in-
creased by 11 pages. A few groups, for instance the gymnosperms, show
considerable changes. Here the fossil families have received more attention.
The Cycadofilicales, which were not mentioned in the seventh edition, are
now discussed. Also the Filicales are rearranged and are now headed by the
Marattiales. Comparatively few changes are made in the angiosperms. The
chapters on plant classification and the outline of floral regions are rewritten
by ENGLER himself, and the new literature finds consideration throughout the
book. Probably ENGLER and Gite did the best od could while handicapped
by lack of literature from English speaking coun

The rapid growth of the Syilabms from Pete sonstitea has undoubtedly
suffered a setback through the war. Nevertheless, the book is still the most
convenient outline of the generally eases beeen which bears ENGLER’S
name, and as a very handy index to his iche Pflanzenfamilien it remains
indispensable to the student of botany. 4 might be added that its oars for
American purchasers is about 150 marks.—A. C. Noé.

A dictionary of botany.—ScHNEIDER and LINSBAUER’Ss? dictionary of
botany lists about 7000 technical terms which are accompanied by short
definitions and cross-references, or by articles of sometimes considerable
length. ScHNEIDER had published the first edition with the help of a large
staff of collaborators, and the second edition was left to the care of Lrys-
BAUER, who is HABEREANDT’S successor in Graz (Austria). The text is
preceded by a short bibliography of botanical treatises and periodicals. ly
German books are listed, and the Annals of Botany and the BoraNIcaL
Gazette are the only English and American periodicals which are mentioned.
Most illustrations are rather old and well known to all students of botany.
Modern plant morphology is largely neglected, except that the embryology

* ENGLER, ApDoLF, and Girc, Ernst, Syllabus der Pflanzenfamilien. 8. Auflage.
8vo. pp. xxxv-+395. figs. 457. Berlin. 1910.

? SCHNEIDER, C. K., and Linspaver, Kart, Handwérterbuch der Botanik.
2. Auflage. 8vo. pp. xxi+824. figs. 396. Leipzig. 1917.

443

444 BOTANICAL GAZETTE [may

of the gymnosperms and angiosperms contains a few illustrations from articles
by CHAMBERLAIN and Miss Pace which had been published in the BoTANICAL

whose death they were revised by Kupart in Graz. In these articles the
work of SEWARD is never mentioned, and Scort is hardly considered.
articles on plant genetics are more up-to-date, and best of all are those on
physiology and anatomy.

The lack of knowledge with regard to American and English botanical
literature is very pronounced in many German publications. The geologists
in Germany know more English because they have to read the publications of
the U.S. Geological Survey.—A. C. No&.

Origin and development of Compositae.—SMALL3 has assembled in book
form his papers on the origin and development of the Compositae, which
appeared in the New Phytologist during 1917-1919. It is an application of
our knowledge of evolution, heredity, and geographical distribution to the
immense amount of material presented by this great family. This study has
been carried on for ten years, and “in so far as success has been achieved in
the unravelling of the tangled skein of descent of this particularly large group of
angiosperms, it is due to the recognition of new criteria and the critical revision
of the old criteria.””—J. M. C.

Joseph Dalton Hooker.—BoweEr’ has written a most interesting account
of Sir JosepH Datton Hooker for the series of booklets issued by the “Society
for Promoting Christian Knowledge,” under the general title ‘Pioneers of
Progress,” and the subtitle “Men of Science.” The titles of the brief chapters
suggest the contents: Birth and education; Foreign travel; Kew; Author-
ship; The species question; Personal characteristics; Hooker’s position as 4
man of science. The author and his style form a combination that insures
authoritative statements and interesting presentation.—J. M. C.

Flowering plants and ferns.—Under this title W1LuIs published the first
edition of his manual and dictionary in 1897. A second edition appeared in
1904, a third in 1908, and now a fourth edition has been published The

is to supply a convenient summary of information about plants, and
the result is a very convenient book of reference. The most noteworthy feature
of the present edition is the incorporation of all the parts of the earlier editions

3 SMALL, James, The origin and cia ml of the Compositae. pp. xi+334-
pls. 6. London: William Wesley & Son.
4 Bower, F. O., Joseph Dalton ee pp. 57. New York: Macmillan Co.
1910.
s Wituis, J. C., A dictionary of the flowering plants and ferns. Fourth edition.
pp. xii+712+liv. Cambridge: The University Press. 1919. New York: G. P.
Putnam’s Sons.

1920] CURRENT LITERATURE 445

into one general dictionary, and the omission of the former part dealing with
morphology, classification, geographical distribution, economic uses, etc.
There are approximately 20,000 entries, so that a wealth of eee aee is
available at a minimum of trouble.—J. M. C.

NOTES POR. STUDENTS
Tropical rain forests.—Two recent.contributions have added considerably
to our knowledge of the ecology of tropical rain forests, especially as bo
present quantitative data concerning habitat and also the vegetation. The
first by Brown® deals with the vegetation of a portion of the Philippine
Islands, and the second by McLEAN? with some of the rain forest near Rio de
Janeiro, Brazil, and is the continuation of a report already noticed.’ This rain
forest of Brazil is regarded as the climax type for a large portion of the country.
A biological spectrum of the Raunkiaer type would show an enormous pre-
ponderance of woody plants arranged in three distinct strata, the ground
flora being comparatively open. There is a great diversity of species, with
the Leguminosae as the most prominent family, and the Rubiaceae and Pipe-
raceae important among the undershrubs. —- and mpcopods are largely
limited to rocky spots. C ndant in the upper canopy
and notably lacking below. ‘Buttressed tree ase are rare, in spite of the
frequency of violent winds, but thorny stems are frequent even in large trees.
The floristic diversity and the contrasting uniformity of appearance, especially
in leaf form, are ascribed to (1) the antiquity of prevailing conditions, and
(2) the peculiarity of the environment. The soil is shallow and pervious,
with a water-holding capacity of about 40 per cent, and an average water
content of 10 per cent. It is deficient in mineral nutrient material and par-
ticularly in calcium carbonate. The humus content is about 3 per cent.
ycorhiza are very abundant. A very considerable amount of rain is inter-
cepted by foliage and evaporated into the air, thus reducing the rainfall
efficiency. Light measurements made with photographic exposure meters
show the btn ratio of the light outside and that within the deep forest to
be 1:0,06; so e spectroscopic measurements, however, tend to show that the
Photosynthetic efficiency of the shade illumination is relatively greater than
the a
The se of the forest are in general characterized by their larger size,

epidermis, reduced and undifferentiated mesophyll, and occasional epidermal

° Brown, W. H., Vegetation of the pagy aie Mountains. hea Agric. and Nat.
are Bur. Sci. ‘Pub. 13:434. pls. 41. figs. 30. Manila. 19
7 McLean, R. C., Studies in the vo of tropical rain fonts with special
reference to the forests of South Brazil. Jour. Ecol. 7:121-172. figs. 10. 1910.
8 Bor. Gaz. 69:92-94. 1920.

446 BOTANICAL GAZETTE [MAY

papillae. The leaf area of the sun foliage is approximately the same as that
of the shade leaves, but the latter are decidedly larger and narrower. Red
coloration is common in the young shade leaves, and such leaves are shown
to have a higher rate of respiration. The percentage of carbon dioxide within
the forest is shown to be high, and here light is doubtless the limiting factor
of photosynthesis.

BROWN agrees with McLEAN in recognizing valley and mountain forest
types, and in addition describes a distinct transition form. The lowland type
of the part of the Philippines a consideration i is the Dipterocarp forest
and extends to an altitude of 600 m. It exhibits distinct strata or stories
composed of vegetation 40, 20, ea Io m. high respectively. Epiphytes are
largely phanerogams, and are confined chiefly to the largest branches of
the tallest trees. Buttressed trees and cauliflora are developed by many
species, while the ground covering is characterized by rattans in the rosette
stage. On a typical plot there were 22 first story species, 43 second story
species, and 23 lower story species.

e midmountain forest extends from 600 m. to an elevation of about
d shows two stories of about 18 and 8 m. in height. One typical
association is termed the Quercus-Niolitsea forest from the most abundant
genera. The undergrowth is less dense, but the ground cover of ferns and
erbaceous plants is better developed than in the Dipterocarp forest.
Epiphytes are also more abundant, and include more cryptogams. Above
goo m. a montane forest is developed, exhibiting a single stratum of vegetation
some 10 m. high, and known as the “mossy forest” from the great abundance
of mosslike plants.

As developed on Mt. Maquiling this last may be termed a C 'yathea-Astronia
association from the two most prominent genera. The herbaceous groun
cover is dense; mosses, filmy and other ferns, Selaginella, orchids, and lianas are
abundant, many growing as epiphytes. Trees are low and contorted in habit.
Statistical analyses are made of all types of forest, the size of the trees as well
as their floristic relationship being given. Detailed data regarding rates 0:
growth of trees seem to show that they are proportional to the heights of the
various forest types. Stations were located in these forests, and at them
measurements were made of environmental factors, including temperature,
light, evaporation, rainfall, humidity, soil moisture, and wind velocity. Many
data were collected and are presented in tables and graphs. Some of the most
interesting conclusions based upon these are: (1) humidity is high at
elevations, and the atmosphere is practically saturated at all times under
the montane forest; (2) temperature gradually decreases with rising eleva-
tion; (3) evaporation in all forests is much less than in the mesophytic forests
of the United States, and decreases rapidly with increasing altitude; (4) there
is a pronounced, although not severe, dry season; (5) only at low elevations
does there appear to be sufficient decrease in soil moisture during the dry
season to have any harmful effect on vegetation; and (6) the increase in her-

1920] CURRENT LITERATURE 447

baceous vegetation with increasing altitude is due to increased soil moisture
and decreased rate of evaporation.

An analysis of the foliage shows that leaves with entire margins are more
abundant in the lower stories than in the upper, and at lower elevations than
at higher ones. Classified according to the system devised by RAUNKIAER,

for the most part, Dipterocarp forest, respectively 4: 79: 9; for the mid-mountain
forest 4:61:5; and for the mossy forest 8:8:0, showing a decided decrease in
leaf size with increase in elevation.

The Philippine vegetation is made more attractive to the reader id
numerous good photographs reproduced on excellent plates.—Gro. D. FULLER

Transpiration studies.—A series of papers by SAYRE? contains some

interesting results regarding si tee from hairy leaves. The leaves of

e in, Verbascum Thapsus, offer more resistance to water loss in dark-

ness than in light, in still air thst in yey and respond rather more to changes

in environment than do the smooth leaves of tobacco, Nicotiana sp. The

removal of the hairs of the mullein leaves resulted in no change of resistance
d

entirely cuticular it appears that, in this plant at least, hairs as a
covering affording protection against a intensities of wind and light
are quite inefficient an ay be disregar stomatal water loss is

a e

20-40 times the cuticular, and only the fatter i is influenced by the removal of
the hai

oisabodos humidity, evaporation, and sunshine were recorded along

increasing the resistance of the leaf to water loss while stomata are open, but
as of no effect after stomata are closed by darkness.

The tobacco and Verbascum Thapsus show a rhythm in the transpiration
curve in darkness for one day only succeeding a day of normal light exposure,
but V. Blattaria exhibits no such rhythm under the same conditions.—
Geo. D. FuLLER.

9 Sayre, J. D. , Comparative transpiration of tobacco and mullein. Ohio Jour.
Sci. 19: 422-426. ke I. 1919
, Factors pect variations in the rate of transpiration. Loc. cit.
19: : 401-500. Sigs. 9.
, The ani of hairy leaf coverings to the resistance of leaves to transpi-
ration. hex: cit. 20:55-75. fig. 7. 1920.

448 BOTANICAL GAZETTE [MAY

A new rubber—Hatt and GOODSPEED,” in connection with the war
demand, have investigated a possible native source of rubber, studying
especially Chrysothamnus. They found rubber of high grade in C. mauseosus,

d ry

presented by Hati.™ Of these varieties, 12 were examined and all found to
contain rubber. The shrub grows readily from seed and matures in 6-8 years.
The largest stands occur in Colorado, Nevada, and Utah; and it is estimated
that the total amount of rubber present in wild shrub is over 300,000,000 lbs.

Chrysil is not a latex rubber, but occurs in individual cells. The results
of 180-chemical analyses and 80 microscopical examinations are tabulated.
The rubber occurs in the plants in greatest abundance about the soil line,
being present in the root in only the upper parts, and occurring in small
amounts in young twigs and leaves. The best varieties for rubber are those
growing in alkaline soils, so that the culture of this rubber-yielding plant could
be developed extensively in alkaline regions unsuitable for other crop plants.

The authors” also give an account of the occurrence of rubber in other
species of Chrysothamnus and in Haplopappus. They also append a long
list of species, chiefly Compositae, in which no rubber was found.—J. M M. C.

Philippine bamboos.—In a recent bulletin Brown and FiscHEer® have
presented much interesting data regarding the taxonomy, ecology, and
economic value of Philippine bamboos. Nine genera, including 30 species,

regarding market pages —, see of much more interest to ecologists is a
series of accurate ord a period of 20 weeks. Growth
rates of 2 m. per week are not uncommon, ea several shoots showed a weekly
growth in excess of 3 m.—Geo. D. Futter.

Salix.—_ScHNEIDER,™ in continuation of his studies of American willows,
has discussed the section Adenophyllae, recognizing 8 species, one of which
(from California) is described as new. The discussions and descriptions are
very full, and are accompanied, by complete citations of collections, so that
taxonomists will be at no loss as to the plants referred to.—J. M. C

* Hat, H. M., and Goopspeen, T. H., Chrysil, a new rubber es searing
nauseosus. "Univ, Calif. Publ. Bot. 7: rBa--264, pls. 18-20. figs. 6.1

u 2 om H. M., Chrysothamnus nauseosus and its varieties. ee 7: 159-151.
19

ALL, H. M., and Goopsprep, T. H., The occurrence of rubber in certain west
Hae Poor shrubs. Tdem 4: 265-278. figs. 2. ss 9.
8 Brown, Wa. H., and Fiscuer, A ci ja bamboos. P.I. Dept. Agric.
and Nat. Res., Bur. ve Bull. 15: pp. 32. mee 33. 1918
SCHNEIDER, CAMILLO, Notes on American widows: VII. Jour. Arnold Arbore-
tum 1: eas tiga:

- VOLUME LXIX NUMBER 6

ELE
DOFANIGAL:: GAZETTE
JUNE 1920

ECOLOGICAL SUCCESSION OF MOSSES
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 266
Reavicks Tivion” |
(WITH TWO FIGURES)

The work on which the present study in moss succession is
based has been confined, with the exception of that done at Mount
Carroll, Illinois, to what may be termed the Chicago region.
This includes localities showing the typical plant associations
within about 40 miles of the city of Chicago. Since the deep
rock canyon type of topography is entirely absent in this region,
a study has been made of the Carroll Creek canyon, east and west
of the town of Mount Carroll, which lies in nearly the same latitude
as Chicago and about 125 miles west. The work was begun
during the summer of 1916 and continued through the years of
1917 and 1918.

The acnenchabie for the plant associations here employed is
largely that used by Cow zes (3) in his ecological work carried on
about Chicago and other localities. Some of these terms may be
traced back to WARMING (13), or perhaps farther. The first
botanist to make use of this classification by which WARMING
divided all plants into xerophytes, mesophytes, and hydrophytes
in connection with bryophytes was WaRNSTORF (14). Since that
time Evans and Nicuots (5) have employed these terms in describ-
ing the mosses of Connecticut. The terms hydrarch and xerarch
were employed by Cooper (2), and are here given the same mean-
ing. The terminology for the classification of the moss species has

449

450 BOTANICAL GAZETTE [JUNE

been confined wherever possible to that given by Grout (7). The
writer is under great obligation for the verification of all species
and the entire classification of many to Mrs. ELIZABETH BRITTON,
of the New York Botanical Gardens, Mr. Georce B. KAISER,
curator of the Sullivant Moss Society, and Dr. LeRoy ANDREWS,
of Cornell University, and for many suggestions and other valuable
assistance to Dr. HENRY C. CowLes and Dr. GeorcE D. FULLER,
of the University of Chicago.

Description of region

The city of Chicago occupies a part of the land once covered
by Lake Chicago (9). This was a post-glacial body of water
formed in the depression between the Valparaiso moraine and the
edge of the retreating ice sheet as it slowly moved northward.
That the water remained comparatively stationary at certain
levels for a considerable length of time after the recession first
began, is proved by the presence of at least three distinctly defined
old lake beaches. The Glenwood beach marks the edge of the
Valparaiso moraine, and is the beach first formed by the impounded
water; the Calumet beach was formed at a later period when the
water was about 20 ft. lower than at the Glenwood stage; the
third or Tolleston beach records a period when the water had
receded until it was 20 ft. below that of the Calumet. The beach
of the present lake is not far from 20 ft. lower than the level of
the Tolleston stage of Lake Chicago, making the surface approxi-
mately 60 ft. below that of the original body of water. Going
northward along the west shore of Lake Michigan one crosses, in
the vicinity of Rogers Park, several old beach ridges of the Tolleston
stage. Here the present lake is eroding material deposited by the
older body of water. Farther north, about Winnetka and Glencoe,
these old beaches have disappeared, and the lake is encroaching
upon a bluff of morainic clay, where may be found all stages of
clay ravines, from freshly eroded gullies to old ravines in an
advanced stage of mesophytism. ‘These ravines have their origin
in the small streams which have cut back into the surrounding
oak upland. Facing the lake the bluffs are in some places entirely
bare of vegetation, while in others they have become well covered

1920] TAYLOR—SUCCESSION OF MOSSES 451

with various species of trees and shrubs, such as Thuja occidentalis,
Juniperus communis, and Shepherdia canadensis. On such stab-
ilized blufis, as well as in. the mesophytic ravines, mosses form a
conspicuous part of the ground flora. At other points north of
Glencoe old dune formations are being eroded. The dune associa-
tions, however, are much better shown at the south end of the
lake, so that no study of mosses on dune sand has been made along
the west shore.

At the south end of Lake Michigan is an extensive sand dune
formation reaching southward for some distance. The finer par-
_ ticles of the material eroded on the west shore are carried by the
water currents toward the south and there washed up on the beach.
The prevailing winds blowing from the lake catch up this fine sand
as it becomes dry and carry it farther inland, thus continuing year
after year the process of dune building (3). At almost any point
which has been left undisturbed by man may be found all stages,
from the bare foredune, through the series of cottonwood, pine,
early oak, and the well established mixed oak dune formations.
At Miller, Indiana, where a part of this work was carried on, the
pine dunes are especially well illustrated to the south and east of
the Grand Calumet River. This stream, which rises in eastern
Indiana and flows almost directly west as the Little Calumet,
makes an abrupt curve south of Calumet Lake. It formerly
flowed eastward as the Grand Calumet, in a course nearly parallel
with that of the Little Calumet, to its outlet into Lake Michigan
north of Miller. Later, sand dunes began to form across the mouth,
and the stream, being extremely sluggish, was not able to remove
the accumulating deposit and was forced to find a new outlet, its
present mouth near South Chicago, thus following the path of least
resistance. The Grand Calumet now remains as a nearly stagnant
body of water which is rapidly filling up with typical pond vegetation.
The dune slopes south and east of this part of the river form one
of the best moss habitats to be found in the dune complex. Much
of the natural flora near the lake and along both banks of the
river is being destroyed by the building of cottages. The level of
the water in the Calumet has been raised by a dam recently built
across the stream farther west. This has not only flooded the low

452 BOTANICAL GAZETTE [JUNE

‘marshy land near the old outlet and many of the pine pannes
north of the river west of Miller, but has submerged the lower part
of a transition oak-pine slope south of the river where a special
study of mosses had been begun in 1916-1917. Another similar,
but perhaps somewhat more mesophytic, habitat is found near
Tremont, Indiana, several miles east of Miller on a slope approxi-
mately at the same distance from the lake, and south of a smaller
stream, Dune Creek, which also flows nearly west for some distance
and here empties into Lake Michigan. This also shows a transi-
tion from the conifer to the deciduous type of trees, but contains
some more mesophytic species, such as Liriodendron Tulipifera and
Acer saccharum, not found at Miller. Mosses are even more
abundant here than on thé transition slope along the Calumet.

In addition to the region about Tremont and Miller the dune
formations have been studied also at Paul, Pine, Long Lake, and
Buffington, all located in Indiana. In all these places the same
general conditions are met. Starting at the Lake Michigan beach
and going southward may be found, in fairly regular order, first
the foredune and cottonwood dune on which there is almost
constant shifting of sand, followed by the slightly higher and more
nearly established pine dune. This is often succeeded by a transi-
tion region of mixed oak and pine which merges into the oak dune
proper, so that the oldest of the series and the one farthest from
the lake is that of the established mixed oak dune on which
Quercus alba and Q. velutina are dominant. These older dunes lie
on the border line between the beech-maple climax region of the
eastern United States and the oak-hickory climax which seems to .
be typical near the Mississippi River. For this reason it is some-
what difficult to determine whether these oak forests belong to the

latter climax type, or are subclimax associations which will in
time develop into the beech-maple type (3).

South of the dune complex just mentioned is another inter-
esting type of topography very completely described by SHELFORD
(10). This is a low swampy area made up of long shallow ponds
or lagoons, nearly 100 in number, sepafated by ridges and extend-
ing almost parallel to the present lake shore. These ridges were
formed by the building up of barrier beaches along the former

1920] TAY LOR—SUCCESSION OF MOSSES 453

shore line, thus cutting off portions of the lake, which then became
lagoons. At one time these ponds drained either into the Calumet
River or directly into Lake Michigan. Much of this drainage has
been cut off by railroad embankments built across the ridges and
lagoons, so that these depressions now exhibit a characteristic pond

ora. Some of the ponds have reached the shrub or swamp-forest
stage; others are dominated by an almost pure stand of cat-tails
or bulrushes; still others, ecologically younger, have a consider-
able area of open water. The ridges in most cases are covered
with oak forests.

In addition to the lagoons, hydrophytic habitats are to be

found in various swamps and bogs which lie within the Chicago
region, all of which offer excellent conditions for bryophytic
development. These may be divided into two main types, those
which have developed from deep kettle lakes and those which have
been formed from shallow lakes or ponds. The former type is
illustrated by the bogs at Mineral Springs and Hillside, Indiana;
while the latter is represented by the swamp forests at Thornton,
Illinois, and Furnessville and Wilhelm, Indiana. The Mineral
Springs bog has been developed by marginal encroachment of
vegetation on the bottom and by formation of a surface mat in
which Decodon verticillatus has played an important part. The
progression has passed beyond the open water of floating vegeta-
tion stage, and even the early stages of mat formation seem to be
somewhat telescoped; but here and there are small areas in which
either the cat-tails, the bulrushes, or the sedges are dominant.
This fen association merges into the shrub stage in which Rhus
vernix, Cephalanthus occidentalis, and Alnus imcana are most
abundant. Beyond the shrub association is the tree area with
Larix laricina, where in places the quaking condition is still quite
evident. In the drier portions of the forest Betula lutea, a tree
rare in the vicinity of Chicago, makes its appearance. The,Hill-
side bog seems to have had the shrub stage, which here comes in
on a dense growth of Sphagnum, continued until the substratum is
comparatively dry, the forest stages having been subjected toa
much greater retardation than is the case at Mineral Springs.
The other swamps mentioned have been produced by marginal

454 BOTANICAL GAZETTE [JUNE

growth of plant life on the bottom only. The Thornton swamp
lies directly south of Chicago and between the Valparaiso moraine
and the Calumet beach line. The Furnessville swamp is east of
Mineral Springs, and at about the same distance from Lake
Michigan. Both of these swamps have reached the forest stage
of development, although there may be standing water in the
depressions in the early part of the season. The third swamp, that
at Wilhelm, is ecologically of a more advanced type. There is
little standing water at any time, and the trees (oak, beech, and
hard maple) indicate the approach of the climax forest.

Nearly all of the other associations under consideration are
located on morainic drift, either within the region once occupied
by Lake Chicago or on the moraine forming the uplands about its
borders. Within the Chicago Lake area this till material has
been somewhat worked over by water action, but not to a degree
sufficient to entirely destroy its drift character. On the east bank
of the Des Plaines River, just below its junction with the Sag, is
the town of Lemont, Illinois. Here there is an outcrop of lime-
stone which forms several small rock ravines. An abandoned
stone quarry in the vicinity, as well as a stone wall at Palos Park
and a quarry at Thornton, offer very similar pioneer rock surface
habitats. East of Lemont near Palos Park on the edge of the
Valparaiso moraine is an upland oak forest which is probably a _
subclimax forest. Excellent secondary successions in cut-over oak
forest in various stages toward reforestation are found south of
Lemont near Joliet. East of Joliet along Hickory Creek near New
Lenox are much more mesophytic oak-hickory upland forests.
At other places we find climax forests of the beech-maple type-
At Smith, Indiana, 4 few miles east of the Wilhelm swamp forest,
and at Otis, Indiana, southeast of Chicago, are primeval wood-
lands containing beech and hard maple of very large size, placing
them without question in the climax area of the eastern United
States. Along the Des Plaines River south of the northern
boundary of Cook County, near Wheeling, Illinois, are mesophytic
forests on uplands in which the presence of Acer saccharum indicates
a greater degree of mesophytism than is frequently met with so
far west in northern Illinois. No Fagus grandifolia has been

1920] TAYLOR—SUCCESSION OF MOSSES 455

found in this region; but the maple may herald the coming of the °
climax forest of beech and maple. Directly east of Wheeling,
along the lake shore at Glencoe, the upland forests are dominated
by oak, although maple is present in the ravines.

The Carroll Creek canyon is a narrow valley with high and in
many places nearly perpendicular walls of limestone. The stream
meanders back and forth across the ravine and frequently washes
against the rock wall. All successions, from the first pioneer
lichens and liverworts to trees with decidedly mesophytic under-
growth, may be found within a short distance of each other. This
is by far the best moss habitat which has been included in the
present study. Although no evaporation data are available upon
this region, it is probable that the excess of humidity over evapo-
ration is greater than in the Chicago region proper; while the
absence of dust from factories and smokestacks may also be a
factor in favor of more luxuriant moss development.

Plant successions

All the successions studied may be placed in two general groups,
xerarch successions and hydrarch successions.

XERARCH SUCCESSIONS

Under the xerarch series are included all successions which
have developed from or through xerophytic stages even though not
xerophytic at the present time. Among the most important of
these within the Chicago region are the successions on dune sand.

SAND DUNE SuUCCESSION.—The lake beach, while not strictly a
dune formation, must necessarily be included in the dune series
leading back from the lake. Here the sand is constantly being
moved, either by the waves or, when dry, by the wind. Even
' during the summer the waves frequently wash over a space several
rods in width; while in winter the effect of water and ice is felt still
farther inland. Very few plants are able to gain a hold under
such unfavorable conditions. Occasionally a few annual seed
plants can be found; and sometimes upon the upper beach seed-
lings of the cottonwood and willows, as well as a few grasses, begin

456 BOTANICAL GAZETTE : [JUNE

a precarious existence. Mosses are entirely absent, no evidence
having been found even of early germination stages. In addition
to the continual change in the surface there is exposure to high
evaporation, another factor very unfavorable to plant life.

The foredunes are a result of the obstruction offered to the sand
laden winds by plants or other obstacles. Among the plants which
may act as windbreaks are Populus deltoides, Prunus pumila, Salix
glaucophylla, and Salix syrticola; or grasses, as Ammophila arenaria
and Calamovilfa longifolia. There is no indication that mosses
ever form a part of the flora. Exposure to evaporation and danger
of smothering by sand are probably nearly or quite as great here
as on the beach itself. As we enter the cottonwood dune, which is
the first of the dune series characterized by trees, we still find
constant shifting of sand. Evaporation, however, because of the
shade cast by the trees, is somewhat less than in the earlier associa-
tion. Gradually the sand increases in height about the trees, which
continue to grow by adventitious roots (3). In time deposit of
refuse from the cottonwoods and growth of ground flora add to
the humus content as well as lead to stabilization of the sand.
Occasionally under the larger trees or on the more protected lee-
ward side of the dune a few mosses may win out in the competition
and live. The first species to appear are such xerophytic forms as
Ceratodon purpureus, Bryum ventricosum, and B.caespiticium. Tf wel
sheltered, these mosses may continue on into the Pinus Banksiana
association; or if exposed by change in direction of wind, may be
entirely killed out before the cottonwoods are replaced by pines.
In no place on the cottonwood dune does there seem to be any
considerable growth of mosses. The species mentioned form only
scattered tufts or cushions, although in most cases sporophytes
are borne freely. Either germination of spores does not often
occur, or the young plants do not survive the unfavorable environ-
ment. These species probably do not spread so readily by vege-
tative growth as do many others.

From the cottonwood to the pine dune we usually find 4
gradual transition, in which Pinus Banksiana begins to appeat
more and more abundantly until the cottonwoods have been
eliminated. At about this time Pinus Strobus becomes mixed

1920] TAY LOR—SUCCESSION OF MOSSES 457

with P. Banksiana on the more mesophytic slopes; and eventually
may form a pure stand. During even the early pine stages we
may find a thick undergrowth of Juniperus communis, with or
without Arctostaphylos Uva-ursi. These may last until the oaks
begin to encroach upon the pines.’ Both the juniper and the
pines produce a dense shade throughout the year, and by shedding
needles form a layer of slowly decaying débris. Under the juniper,
particularly on north facing slopes, we find the most abundant
moss growth of the dune series. Beyond the juniper, where
Arctostaphylos is very thick, mosses may. be present but are less
continuous. The bearberry is a plant of low trailing habit, and has
the effect of shutting out the relatively small amount of light
which penetrates through the dense covering of conifers, and renders
photosynthesis on the part of the mosses: difficult. The most
abundant species of moss under the juniper is Thuidium delicatulum,
ordinarily considered very mesophytic. Here it forms a thick
continuous mat frequently excluding all seed plants as well as most
other moss species, and extending beyond the juniper in many
places. In this moss mat is a much smaller quantity of T. recogni-
tum, not mixed with the 7. delicatulum but growing in similar
places and forming small but distinct portions of the mat. A
still smaller amount of 7. abietinum appears occasionally. Scat-
tered through the Thuidium in very small quantities are two
other mesophytic species, Hylocomium triquetrum found at Paul,
and Calliergon Schreberi found at Miller. Both species are common
in the mesophytic forests farther north (2). About 15 other species
of mosses occur upon the pine dune. Some of these are found
occasionally under the juniper, but more often on the sand in open
places free from juniper, around the bases of trees, or on half-decayed
sticks. The most common of these are Ceratodon purpureus,
Dicranum scoparium, and Funaria hygrometrica, all of which are
species of fairly varied habitat. Much the same condition has
been found in all of the pine dunes studied. The mosses are most
abundant in total quantity and are most luxuriant on north
facing slopes, which in this region are also lakeward facing slopes.
A greater number of species occur here than elsewhere in the
dunes, unless it is in the transition oak-pine regions, where many

458 BOTANICAL GAZETTE [JUNE

of these species continue on as relics while new ones make their
appearance.

Just west of the pine dunes at Miller and south of the Grand
- Calumet is such a transition region of mixed pine and oak. Along
the slope near the river is an abundant growth of mosses, but
nowhere except close to the water do they form as complete a cover-
ing as in the pine association. Toward the top of the slope they
become scattered, and there is also a decrease in the number of spe-
cies. Thuidium delicatulum continues on the lower slope with some
T. recognitum. Other types found among the conifers are mixed
with new species, one of the most common of which is Fissidens
cristatus. Other forms, either new or now much more abundant,
are Mnium cuspidatum, Thelia Lescuriit, Anomodon rostratus,
Climacium americanum, and Rhodobryum rosewm.

As mentioned previously, another ecologically more advanced ~
transition slope occurs south of Dune Creek near Tremont, Indiana.
Conditions here are even more favorable for mosses than at Miller.
The presence of such trees as tulip and hard maple before the pines
are entirely gone would indicate a telescoping of the oak stages and
the rapid advance of the climax forest. The same relative dif-
ference in scattered moss patches on the upper slope and almost
continuous mat near the base is noticeable here as at Miller. The
most conspicuous species is Aulacomnium heterostichum, bearing
numerous sporophytes. Other mesophytic species not mentioned
before are Bartramia pomiformis, Catharinea undulata, and Dic-
— ranella heteromalla. Anomodon attenuatus occurs in dry situations,
usually on tree bases. As already mentioned, both of these
transition slopes are near the lake, north facing and south of
streams. In striking contrast to these are transition slopes directly
south of the pine dunes, farther from the lake, and not in close
proximity to streams. Here we see a rapid thinning out of the
moss flora. The more mesophytic species disappear entirely and
only a few new forms come in. These resemble the types found at
the xerophytic tops of the more mesophytic transition slopes.

In the early stages of the oak dune proper, either farther west
along the Calumet or south of the pine dunes at Miller as well as
at Paul and Furnessville, the mosses are still scattered. In

1920] TAYLOR—SUCCESSION OF MOSSES 459
ravines, however, on slopes with a northern exposure or otherwise
protected from desiccation, certain species may be fairly frequent.
Thelia Lescurii, a gray-green moss growing in loose mats, is
dominant and sometimes covers areas of several square feet.
Anomodon rostratus also appears frequently, and A. attenuatus
occasionally. Climacium americanum and Rhodobryum roseum
may be found in sheltered spots but not in large quantities.
Ceratodon purpureus is characteristic in open, less shaded places,
while Catharinea undulata occurs here and there. A thick con-
tinuous moss carpet is never found among the oaks as in the pine

TABLE I
PRESENCE OF MOSS SPECIES IN ASSOCIATIONS OF SAND DUNE SUCCESSION

Species Cottonwood Pine sme Oak Beech-maple
Anomodon rostratus.....].......... Lg P 1 ER ee Ripe aie Seer
Bryum ventricosum..... P i ee is ee es
ryum caespiticium..... Ls Rit ead pacer eae Lah thoes asany far itioy eae Alteae

Catharinea undulata....|.......... Pe tg Ae P
Ceratodon purpureus. . P r P | ee en ea
cium americanum..|.......... P P oe ping ta yw canes
Fissidens cristatus. .....|... ss» 0: r P Pe ae ak
Funaria hygrometrica...|.......... ig Pr Pore i.e
Leucobryum glaucum....{........-. ig P Be yt
Mnium cuspidatum.....|.......... P P EES RereaO ROE
ocobryum roseum .. 7. fo0000 6.5 sk eee os P | de ae aes
Thuidium delicatulum...}........ i Pp Po et.
Thuidium recognitum...}.......... r Pr Pos
a gn oo eve ke P Po es
I Lo a an pecs P Po a |

dune.

As we go still farther south into the later stages of the

oak associations, the moss flora becomes less, until about the only
species left are Thelia Lescurii and Catharinea undulata in shaded
places, with Ceratodon purpureus and rarely Bryum argenteum
where the sand is more exposed. In forests where white oak is
dominant and the forest floor is free from fallen trees, as is the
case in many oak forests in this region, Catharinea undulata is
usually the only moss species to survive. Table I shows the suc-
cession of mosses as they have been found in the xerarch series of
the sand dunes. P indicates presence of species. Only the
species which occur in two or more associations are included.

460 BOTANICAL GAZETTE [JUNE

Why is it that we find this great variation in the moss flora
within such a relatively small area as that included within this
dune complex? There seem to be at least three causal factors
which are worthy of special consideration. First is the constant
transportation of sand; second, the exposure to high evaporation;
third, and in this case of least importance, competition with other
plants. Mosses, because of their low growing habits, are not able
to endure covering. Even with such a genus as Sphagnum,
which is able to continue upward growth year after year, and which
has tall erect stems, it is not unlikely that a deposit of sand or
sediment would entirely destroy its power of regeneration. There
is much less probability that other species which do not have
this advantageous habit could contend successfully against cover-
ing. Numerous places occur within this region where, through
rejuvenation of some dune area, the sand is being carried over
more or less mesophytic regions. North of the Grand Calumet
near Miller are dunes which have reached the pine stage and >
which contain many of the species of moss found in the pine dunes
south or east of the river. Recent changes, largely due to man,
have brought about rejuvenation of the dunes to the windward.
The mosses are now in many places early destroyed by smother-
ing, because of the fine sand accumulating about them, and the
whole slope, once mesophytic, is undergoing a retrograde succession.
Thus it seems quite certain that any dynamic condition which
will lead to covering will also bring about the death of any mosses
already existing, as well as preventing the growth of the pioneer
species. Contrary to the once common opinion, the soil of the
new dune is not dry, except near the surface. The water table is
always high, and it is necessary only to remove a thin layer of sand
to find moisture, even during dry weather. The exposure to
evaporation may be great, and this without doubt is the leading
cause of the xerophytic structures to be found in dune plants,
rather than non-availability of the water supply (6). The work
of FULLER gives data upon evaporation in the dune associations,
secured in this same region north of Miller. The results regarding
the difference in the evaporation rate verify in a marked degree
the conclusions to be drawn from the location of the xerophytic

1920] TAYLOR—SUCCESSION OF MOSSES 461

and mesophytic types of moss. Stations for the location of the
atmometers were selected in the cottonwood, pine, and oak associ-
ations near Miller, and for the beech-maple association at Otis,
Indiana. The last, however, is upon morainal clay and not on
dune sand. It is not necessary to enter into a detailed account of
these results. Fig. 1, taken from FuLter’s work, shows the
average of the mean daily evaporation rates in these associations
for the three seasons 1910, 1911, and 1912. Fig. 2 indicates the
curves for the average of the mean daily evaporation rates in the
four associations for the growing seasons of these years.

The absence of mosses on the beach and the foredune is due
to the continual change in the surface material and the exposure

0 10 20

Cottonwood dune
Pine dune

Oak dune
Beech-maple forest

Fic. 1.—Average of mean daily evaporation rates for the 4 associations for
Seasons Ig10, IQII, 1912.

to evaporation. Competition with other plants does not enter
into the question. There is not the struggle with wave action on
the foredune as on the beach, but there is still constant movement
of sand by winds. The plants forming the nucleus of the foredune
Cast little shade, so that both desiccation by sun and wind and the
probability of being covered by sand are as great as on the beach
below. The cottonwood dune is higher, the trees afford much
more shade, humus begins to accumulate, and as the dune tends
toward stabilization there may be much greater protection from
wind on the leeward side. However, even on a moderately windy ©
day fine sand is deposited over the ground vegetation so that
there is still the struggle to overcome the tendency to covering,
and for opportunity for photosynthetic work on which the life of
the mosses depends. Evaporation by exposure to bright sunlight
and strong winds, while still high, may be somewhat less than on

462 BOTANICAL GAZETTE [JUNE

the foredune. All of these causes tend to exclude any but the
most hardy species, and even these are never abundant. The

MAY JUNE JULY AUGUST SEPTEMBER OCTOBER
SS
3 \ fed.
tt Hon i
ine Hs:
i Bie
ICT mie
| I] Guinea i: oe
[ \ I \ os
¥i
\ ae
SN
NI
Z as 7
15. Lue \ fe 2
\ a ‘ eh Em
aa 7 NlST H. i ie
ne a iat . ae
rie : ACE
\—iL et eal
5 i “he
Cottonwood dune-—————_______ e x ¥ cs fh 2
ok ee ee vatleca et
Oak dune ie
Beech-maple forest — — = —

Fic. 2.—Average pes mean daily evaporation rates in the 4 associations for grow-
ing seasons Igi0, Igtt, 19
struggle with other plants is not important, since there are always
many unoccupied places, and the supply of available moisture is
plentiful.

1920] TAY LOR—SUCCESSION OF MOSSES 463

In the pine dune there is a much greater difference in the effect
of the first two-factors, moving sand and evaporation. It is here
and in the mesophytic transition regions that the third factor
enters into the causal conditions. According to the results of the
evaporation work done by FULLER, the pine dune shows the lowest
evaporation rate to be found among the tree associations of the
dune series, other than the climax forest. It is still more significant
that the rate is lower during the early summer and late fall,
the most vital part of the season for mosses. The débris upon
the ground aids in the absorption of moisture during rains. The
moisture as it slowly escapes from the soil is confined near the
surface by the close canopy of the juniper, and also by the dense
overhead covering of pines. All of this leads to a high degree of
humidity during spring and autumn, the seasons of greatest rain-
fall, not found elsewhere in the dune associations. In midsummer
evaporation may surpass that of the oak dune (fig. 2), but the
mosses by that time have passed their period of vegetative growth,
and in many cases the production of sporophytes also. The matur-
ing of sporophytes in other species, such as Thuidium, is carried on
late in the season when humidity again rises. The fact that we
find 7. delicatulum as the dominant species under the juniper
indicates decidedly mesophytic conditions, for except as a relic
this species usually occurs only in moist habitats. Another reason
for its dominance seems to be its ability to endure shade.. Either
there is no competition with other plants under the juniper or
such plants have been crowded out, while Thuidium thrives best
when well shaded. Other plants become competitive beyond the
juniper where herbaceous vegetation, including several typically
northern species, becomes more frequent. Thuidium less often
covers extensive areas, and seed plant y even be found germinat-
ing on the mosses. In places more favored by light the mosses are
likely to lose out altogether or be forced to take refuge on sticks
or bases of trees. Another factor which seems worthy of consider-
ation is that Thuidium grows directly on the slightly decayed
needles of the conifers. These probably produce a chemical
condition of the soil which effectively eliminates many other
plants. While the pines also shed their needles, there is much

464 BOTANICAL GAZETTE [JUNE

less material of this kind where the juniper is absent. The com-
petition with shifting sand is nearly absent unless the dune is being
rejuvenated. The deposit isso slight that it does not seem to retard
either the germination of spores or spread by vegetative growth. -

The two mesophytic transition regions from conifer to oak
offer nearly as favorable moss habitats as do the pine slopes. Many
of the species are relics from the more shaded former conditions,
but which now are losing out, largely it would appear by encroach-
ment of other light tolerant mosses, rather than because of competi-
tion with herbaceous plants. The shade is much less; especially
during late fall and early spring. Many of the mosses are scarcely
evident during midsummer. Most of them produce many spo-
rophytes and mature thé spores early in the year. That the
relative humidity is at times increased by nearness to the water
was quite evident on several trips to Miller-when the weather
previously had been warm enough to raise the temperature of the
water of the Calumet. A strong cool wind from the north carried
the mist, which was ascending from the river, directly over the
transition slope. It was not learned how frequently this happens,
but a considerable amount of moisture must be deposited during
even a few hours of such a mist. This difference in humidity and
water supply is probably one of the chief causes of variation in the
luxuriance of the mosses on these slopes and on those farther from
the lake, and not in the vicinity of other bodies of water. The
- evaporation rate at other times is very likely higher than on the
pine dune, but unfortunately there are no data for evaporation on
these transition slopes. Neither competition with other plants
nor movement of sand is a very important factor, unless it may be
the latter near the top of the slope.

On the oak dunes we again have an evaporation rate higher
than that of the pine dune, except in midsummer. The sparse
undergrowth in many places gives little protection from the
hot sun which penetrates through the foliage of the oaks.
During the spring and fall there is great exposure to somewhat
desiccating winds. On many of the more mesophytic northward
slopes where mosses might be expected there is often a dense
growth of vernal herbaceous plants which seem to have crowded

1920] TAYLOR—SUCCESSION OF MOSSES 465

out the mosses, until the latter are found only on decayed sticks
or bases of trees. A few relics from the pine association occur
here and there. On some slopes and in ravines where herbaceous
forms have not taken full possession, mosses are more common.
As previously mentioned, these are somewhat xerophytic species
which appeared only rarely in the earlier succession, together wit

some relics from the former association. It is possible that the
roots of the herbaceous plants, because of the need for moisture,
rob the surface soil of its water and thus make it more difficult for
mosses to secure a sufficient supply. Competition, therefore, can
be said to be the great limiting factor on the more mesophytic
slopes; while low humidity and high evaporation seem to be
more important on those facing the south, where neither mosses
nor herbaceous plants are very abundant. Sand laden winds are
not of much importance unless the area is near a rejuvenating
dune. In the older stages of the oak succession the forest becomes
more mesophytic. There is less evaporation and higher humidity,
with entire lack of covering by sand. Humus has now accumulated
to a degree necessary for the growth of many more species of seed
plants. Apparently these have become so successful as to cause
almost total elimination of the mosses, which have contributed
to their own extinction by adding to the humus content. Only in
exposed paths or roads, on decaying logs, or sometimes on tree
bases, do the mosses continue to exist at all. Old logs are rare in
these woods, and only bases of old trees are favorable habitats, so
that in the advanced oak association in this region the moss flora is
often almost confined to a few species which spring up in paths or
tracks left by the feet of animals.

We may summarize the causal factors for presence or absence
of mosses in’ the dune succession as follows. Mosses are excluded
from the flora of the beach and foredune by great exposure to
desiccation and to covering by sand. Xerophytic species may
appear on the cottonwood dune, but are prevented from becoming
conspicuous by these same two factors. Mosses suddenly become
abundant in the pine dunes, their growth being favored by high
humidity and low evaporation during spring and fall, a result
largely of the shade cast by the pines and juniper. Competition

466 BOTANICAL GAZETTE [JUNE

with other plants begins, but is not of great importance; while
that with shifting sand has nearly ceased. Whether the moss
flora of the transition conifer-deciduous regions resembles more
nearly that of the former or of the latter type seems to depend
chiefly on local conditions, such as adjacent bodies of water and
exposure to winds, greater humidity tending to increase the growth
of mosses, and a high evaporation rate bringing about their destruc-
tion. In the oak dunes the higher evaporation leads to elimination
of the relic species, while it may also lead to the appearance of new
xerophytic types. Competition with other plants, especially vernal
herbs, becomes a deciding factor, while that of moving sand may be
omitted from consideration.

MoRAINAL CLAY SUCCESSIONS.—The early stages of moss
succession on morainic drift were studied near Glencoe, Illinois.
On newly eroded bluffs along Lake Michigan mosses are absent,
and in fact do not appear until after other vegetation has begun to
take possession and the surface is no longer subject to very active
erosion or slumping. On slopes partly covered with Juniperus
communis, with or without Thuja occidentalis, mosses, while con-
spicuous, do not form a mat of large extent. The species are almost
identical with those on sand at Miller. Anomodon rostratus, Thelia
Lescurii, and Thuidium delicatulum are the most common. The
same similarity on dune sand and morainic clay bluffs has been
noted by Cowtrs (3) for the higher plants. Neither do mosses
appear in the early stages of ravines while vertical erosion is active.
In later stages, however, they become important and may take no
inconsiderable part in stabilization of the surface. Unfortunately
it was not possible to study ravines of all degrees of mesophytism,
so that the exact period at which mosses appear was not deter-
mined. Most of the work was done in ravines having sides of
rather gradual slope covered with a subclimax forest and meso-
phytic undergrowth. A vertical succession, not so evident on the
dune slopes, is here a noticeable feature. In one such ravine
Polytrichum commune is conspicuous among the arbor vitae at
the top. Just below this is a good display of Catharinea undulata.
About midway down the slope is a mixture of mesophytic species
such as Bartramia pomiformis, Dicranella heteromalla, Anomodon

1920] TAYLOR—SUCCESSION OF MOSSES 467

rostraius, and Mnium cuspidatum; while the lower third of the
slope is nearly covered by one hypnaceous species, Plagiothecium
deplanatum. ‘The entire surface is well supplied with herbaceous
undergrowth, but this has not yet been able to supersede the
mosses, which, because of absence of decaying woody material,
are andl almost entirely on the ground. As the ravine widens
and enters upon its second period of denudation, more light enters,
and the mosses are gradually eliminated by their being a favorable
habitat for the germination of seedlings of higher plants which can
endure a greater degree of evaporation.

The oak uplands adjoining these ravines are characterized by
an extremely impoverished moss flora with the exception of Catha-
rinea undulata, which may occur frequently. This is almost
equally true of the oak-hickory morainal forests at Joliet, New
Lenox, and Palos Park. Catharinea undulata is present in all,
Physcomitrium turbinatum occurs along paths, and at Palos Park
Leucobryum glaucum is an occasional species. At Wheeling,
Illinois, just west of Glencoe on the Des Plaines River, are upland
morainal forests which are much more mesophytic than those
just mentioned. Of these we may make two general divisions:
those which have been pastured so that there are few shrubs and
the herbaceous growth is almost confined to grasses, and those
which have a mesophytic undergrowth both shrubby and her-
baceous. In the unpastured woods, as a marked contrast with the
other oak woods just mentioned, mesophytic mosses are common
both on logs and on the ground. Among these are Thuidium
delicatulum, Mnium cuspidatum, Catharinea undulata, and Clima-
cium americanum. In the more open woods which have been
partly cut over and subject to grazing, these same species continué
on as relics, but are less abundant than before. With these may
be Leucobryum glaucum, Dicranum scoparium, Polytrichum com-
mune, and Ceratodon purpureus. It is not unusual to see, rather
large areas given over to Leucobryum and Dicranum alone or mixed
with Polytrichum, Catharinea, and Thuidium. Close to the river,
however, along the well drained bluff, we once more find only
Catharinea on mounds and Physcomitrium with sometimes Funaria
_ hygrometrica along paths and in tracks.

468 ; BOTANICAL GAZETTE [JUNE

What is probably the ultimate forest of the region and the
climax of the morainic series, the beech-maple type, is seen at
Otis and Smith, Indiana. No mosses except Catharinea have been
found in these forests in any place except on decayed wood or in
water holes, In ravines in the Otis woods where humidity is
higher (figs. 1, 2) mosses are a little more common, not growing on
the ground, ud on sticks, stumps, or bases of trees. These are
almost invariably some species of Hypnaceae.

Of the three leading causal factors mentioned for the sand
association, water erosion may be substituted for wind erosion
and covering. As long as very active denudation continues on a
ake bluff or ravine slope, resulting either in a gradual wearing
down of the surface or in slumping, mosses have no chance to be-
come established. While evaporation on the bare slope may be
excessive, neither that nor competition with other plants is the
primary factor. In the later stages, however, these become the
two determining conditions. Wherever the arbor vitae and
juniper are present we have a repetition of approximately the same
conditions as under the pines and juniper on the dunes. The
arbor vitae is near its southern limit at Glencoe and does not
form a thick cover, and for this reason has less influence as a shade
producer than has the pine. On the other hand, the juniper
may be just as dense and as effective in producing shade and in
retaining moisture as in the former situation.

Uxricu (12) has made a study similar to that by FULLER in the
ravines at Glencoe. Three stations were used which correspond
roughly to the three elevations on the ravine slope just described,
and the results justify the supposition that evaporation is the
main cause of such a difference. The station near the top in what
would correspond to the Polytrichum area showed the highest rate
of evaporation; that on the middle of the slope or the regiori of
mixed mesophytic mosses gave a lower rate; that at the bottom
or the area of Hypnaceae gave a still lower rate during a part of
the season, although at times it was slightly in excess of that mid-
way up the slope. This is exactly what we would expect from
the nature of the species present and a comparison of the conditions
in other regions where they are found. Competition with other

1920] TAY LOR—SUCCESSION OF MOSSES 469

plants is no doubt an important factor on many such slopes, as
they offer. conditions increasingly favorable to other ground flora.
Erosion decreases in importance as a determining factor in pro-
portion as the mesophytism increases. When the ravine reaches
its second denudation period, accompanied by greater sunlight
and evaporation, the mesophytic mosses are eliminated along
with the other mesophytic undergrowth; but these may reappear
when the slope has once more attained a relatively permanent
condition, and continue on until the climax association is reached,
or may even iieane into this association if logs and stumps are
present.

In the open oak forests the moisture supply in air and soil
probably is again largely the controlling condition, as in the oak
forests on dune sand. Other plants do not occupy the ground to
so great an extent as to exclude mosses because of lack of space
alone, and there is little probability that the mosses would be-
come shaded to a sufficient degree to shut out the light and prevent
the necessary photosynthetic work. Just why there is so great
a scarcity of mosses in the more mesophytic oak or oak-hickory
forests, as well as in the beech-maple climax, both of which pro-
_ vide relatively high humidity and low evaporation rate (6), has
not been fully determined. Competition with other plants may
be accountable to a great extent, but even this does not seem
sufficient to cause the almost complete elimination of mosses from
these forests. In some places there is a continuous succession of
dense ground vegetation during most of the growing season, which
might be able to prevent the development of mosses; but in other
Places the vernal flora does not seem to be followed by a con-
spicuous aestival flora, yet mosses are not present. Perhaps the
competition with the vernal flora in its prime, when most mosses
attain their greatest growth, may be sufficient to prevent both
spore germination and vegetative growth at this time, so that
presence or absence of ground vegetation later in the year is of
little consequence. The fact that when old logs are present,
mosses are common upon them when not found on the ground,
would indicate that they had not been able to hold their own
against the herbaceous plants. Another factor which may have a

470 BOTANICAL GAZETTE [JUNE

decided influence is that of the chemical change in the soil due
to increase of humus. Just what the difference is which seems
favorable to the germination of the seedlings of the climax trees
and not to those of the former association, and how much of this
difference is chemical and how much physical and related to
light, are questions for future solution. Whatever it is, it would
probably affect mosses as well as other plants. That an acid
condition of the substratum alone is not detrimental is indicated
by the luxuriant growth of many species on decaying wood and
upon needles of conifers.

The great abundance of mosses in the upland oak-forests along
the Des Plaines River seems to be related to the slightly greater
humidity of the atmosphere and larger supply of available soil
moisture. There are indications that much of this region has
been and still is at certain seasons somewhat swampy, so that
there may be some question whether it belongs in the xerarch
succession proper or should be placed in the hydrarch swamp
series. While the final outcome would be the same in the two
series, the intermediate successions would differ to a very large
degree. The presence of the relic species in the grazed woods
or partially cut-over land seems to be explainable by the fact
that they are mosses of wide extremes of habitat, and are highly
light tolerant. The change in environment appears to have taken
place so gradually that the mosses have been able to become
adapted to the greater xerophytism without themselves being
materially altered. :

The successions on morainic drift may be summed up in a
few points. Mosses are entirely absent on the newly eroded
bluffs and in the early stages of the ravines. They do not become
conspicuous in the ravines until a rather advanced state of
mesophytism has been reached, but they probably play an impor-
tant part in the stabilization of the clay surface and addition of
humus, which hasten the advance of the seed plants. Mosses
appear in the conifer stage on the blufis, forming part of the heath
mat under the juniper. They are most abundant in the middle
aged ravines, before the second xerophytic stage is initiated by the
widening of the ravine and decrease of the angle of the slope.

1920] TAYLOR—SUCCESSION OF MOSSES 471

- On the oak upland and in most oak and oak-hickory forests of
the subclimax type mosses are nearly absent, particularly where
decayed logs are not to be found. The same paucity of mosses
occurs in the beech-maple climax forests of this region, where
competition with other plants or chemical conditions of the soil
may be the leading cause. The increase in moss flora along the
Des Plaines River at Wheeling seems to be a result of former and
present better supply of moisture in soil and atmosphere.

Rock succESsIONS.—The rock successions are poorly repre-
sented in the Chicago region. The early pioneer stages of lichens
and mosses, however, can be distinctly traced at Lemont, Illinois,
near the Des Plaines River, on rocks of Niagara limestone which
have recently been exposed, on the sides of an old stone quarry,
on a cliff in an open pasture, and in several small ravines. The
early crustose lichens are followed by Brywm argenteum and
Grimmia apocarpa. Ceratodon purpureus seems to succeed these
or even to appear with them on the flat rock surfaces, either on the
top of the cliffs or on the bowlders. Many rocks have been exposed
during recent excavations in straightening the channel of the
stream. . These are frequently well covered with crustose lichens,
and the first moss to invade the lichen zone is Bryum argenteum,
so that in this case at least this species is a pioneer moss. Else-
where on rocks it seems often to come in later than Grimmia. At
the mouth of the ravines, wherever the rocks are still exposed to
xerophytic conditions, the struggle is going on between the mosses
and lichens. The pioneer mosses usually smother out the crustose
lichens, but in turn may be covered up by small species of the
foliose lichen group. The mosses here never become very abundant,
nor do they occupy large spaces. On the vertical faces there are
numerous small cracks and pits in the rock which offer a better
hold for typical crevice species, such as Funaria hygrometrica and
Gymnostomum® rupestre. Crevice forms are somewhat more
abundant in the cracks of a stone wall at Palos Park where the
mortar has disintegrated. At the quarry near Thornton, where
the horizontal surface of the limestone has been denuded, there
are numerous patches of Funaria hygrometrica and Ceratodon pur-
pureus. Within the limits of Chicago, at Stony Island, although

472 BOTANICAL GAZETTE [yuNE

the rocks have been long exposed, only very depauperate specimens
of these same species occur. The later stages of the rock suc-
cession are absent. All of these places, with the exception of
Stony Island, are surrounded by agricultural lands, and whatever
has been the natural fate of this series has been too nearly obliter-
ated by man to allow of its determination. At Stony Island the
top of the rock is covered with prairie vegetation. The presence
of a few oak trees seems to indicate that without the intervention
of man the grasses would have been followed by an oak forest.
The conditions at Lemont may have been much the same. In the
ravines themselves the mosses belong almost without exception
to the Hypnaceae and are without sporophytes, and hence are
difficult to determine. Brachythecium digastrum is a rather com-
mon species.

The Carroll Creek ravine, where humidity is much greater
and there is considerable seepage of moisture over the rock sur-
face, is a much more favorable habitat for mosses than are the
rock outcrops in the Chicago region. The number of species is
not large, but those which do occur are plentiful and they form a
thick covering over the rocks. Wherever the stream comes in
contact with the rocks, and in other very moist places, liverworts
are the first plants. Above the liverwort zone, or on rocks less
closely in contact with the water, is the zone of crustose lichens.
These are usually followed by foliose lichens, although quite
often the pioneer mosses may succeed the crustose and contend for
possession with the foliose lichens. The first moss is Grimmia
apocarpa. On rocks in the open, exposed to strong insolation the
greater part of the day, this species is abundant both on horizontal
and vertical surfaces. Accompanying this is Brywm argenteum,
which may occur almost if not quite as early, and in even greater
quantity, particularly on horizontal surfaces.

his region offers the best illustration of a very definite suc-
cession of mosses on mosses. Here a second or even third moss
stage is common and may occur on rocks in the open as well as on
ose in mesophytic shaded places in the ravine. The species
which constitute the later stages differ in the two situations. In
sunny places Bryum argentewm frequently forms the second stage,

1920] TAYLOR—SUCCESSION OF MOSSES 473

with some Hypnaceae as the third vertical layer. An especially
good example of this was found on a low rock situated on a hill-
side in an open pasture, and at some distance from the stream. The
top of the rock sloped a little in the downhill direction and was
slightly lower than the ground at the upper edge, but was perhaps
2 feet above the ground at the lower side. Numerous bushes
overhung the upper border, but the lower part was exposed to
full sunlight. On the shaded vertical face was a small quantity of
a liverwort and an extensive growth of crustose lichens. The
liverwort did not grow over the edge at the top, but the crustose
lichens which had spread over much of the upper surface were
being overgrown by foliose lichens. Growing among and over
these was Grimmia apocarpa. Overlying the edge of the Grim-
mia and in many places entirely covering it was Brywm argenteum,
forming a thick compact mat over a large part of the remainder of
the rock, except at the upper side where soil had washed over the
surface from the ground in contact with it above. Here Brachy-
thecium acuminatum, growing partly on the soil, was extending out
over the Bryuwm, forming a third moss layer. Small patches of
lichens and of Grimmia here and there indicated that these at oné
time had been pioneer plants over the entire surface. When the
two more mesophytic species came in, they had developed more
rapidly on the part of the rock which received the most moisture
from the ground and which was also somewhat shaded by over-
hanging bushes.

*In shaded places along the creek in the ravine proper several
species of Anomodon form the moss stage following the pioneers.
As would be expected, the change in species occurs more rapidly
in spite of the slope of the rock, which more nearly approaches the
perpendicular. In some places the cliffs are quite closely covered
with Juniperus virginiana and deciduous trees and shrubs. Under
these and often overhanging the edge of the cliff is an undergrowth
of Taxus canadensis, reminding one of the Juniperus communis
under the pines in the dune region, except for the greater meso-
phytism which is indicated by the herbaceous flora. On vertical
rock faces, well shaded and with water dripping over the surface,
a luxuriant mass of Anomodon viticulosus is the only common

474 BOTANICAL GAZETTE [JUNE

species. On surfaces with a more gentle slope, where the moisture
supply is somewhat less but still plentiful, this species, either
alone or with Anomodon rostratus, forms the second moss stage.
Where exposure to evaporation is greater, Anomodon rostratus
alone, of the two species, occurs. Under the Taxus is a close moss
carpet in which Thuidium delicatulum forms the third moss layer,
and the second species is ordinarily Anomodon rostratus, which has
smothered the Grimmia except at a very few points. Other species
which help to make up this moss carpet often several inches thick
are Climacium americanum and Rhodobryum roseum. This seems
to be a moist habitat even during very dry periods. Another even
better successional series was found on a rock on a more gradual
slope, well shaded by deciduous trees of an older ecological associ-
ation, and well above the level of the stream. This rock projected
out a short distance from the bank, leaving a small space between
the rock and the ground below. On this protected lower surface
Fissidens cristatus formed a complete covering and in places
extended up over the edge of the rock. Growing over this on the
upper surface and reaching down over the edge at some points
was a thick mat of Anomodon rostratus. Upon the Anomodon
was a third stratum of Thuidium delicatulum and a small quantity
of Entodon cladorrhizans, in all forming a compact mat of consider-
able depth. No traces remained of the typical pioneer mosses.
The lichens showed occasionally under the Fissidens. On the
Anomodon were patches of a powdery lichen and also of a fruticose
species, showing that these may develop on the mesophytic mosses.
Climacium and Rhodobryum again formed a small part of the last
moss stage. Growing in this carpet of moss were such plants as
Pilea pumila, Geranium maculatum, small ferns, and tree seedlings,
indicating that the next succession is to be that of the vascular
plants. Many such examples of the vertical succession of mosses
are to be found throughout this ravine.

Such a moss carpet has been described by Cooper (2) for the
rock surfaces on Isle Royale, and by Braun (1) for the conglomer-
ate rocks near Cincinnati, Ohio.

At the top of the perpendicular cliffs there seems to be no
special variation in mosses. Backward from the margin the same

1920] TAYLOR—SUCCESSION OF MOSSES 475

pioneer xerophytic species soon give way to the more mesophytic
ones. From the edge there is usually a rather abrupt slope upward
for a few rods, which is thickly wooded, in most cases with oaks
sparsely sprinkled with red cedar, and here and there a white pine.
The undergrowth is decidedly mesophytic, and on the rocks are
the same mosses already given for the other moist shady habitats.
Immediately beyond the strip of wooded land are cultivated
fields.

In comparing the sparse moss flora on rocks of the Chicago
region with the very luxuriant display along Carroll Creek, where
general climatic conditions must differ only slightly, one at once
begins to search for the cause of the variation. While the rock
exposures around Chicago are not extensive, they are sufficient
to serve as a basis of comparison. The rock in both cases is
dolomitic limestone, not differing enough in structure to be an
important factor. The only outcrop which is near enough to
Lake Michigan to be affected by the greater humidity is that of
Stony Island, and that is, if anything, more barren than are the
other regions. The cliffs and ravines at Lemont are not close to
the stream as are those at Mount Carroll, but are on what was
probably the river bluff at some past period when the stream
contained much more water than at present, in all probability
when the Des Plaines River was the outlet of the old Lake Chicago.
Now the cliffs are not near any body of water, and in the ravines
are only small streams which are nearly dry a part of the year.
The stone quarry at Thornton is being worked by a cement factory,
so that the exposure, with the exception of the rocks along the
top, is too recent to afford any information. The amount of
moisture which could come from the pool of water in the bottom of
the quarry cannot be great enough to affect the flora on the
horizontal rock surfaces above. The quarry at Lemont has been
abandoned for some time, and much of the bottom is overgrown
with weeds and grasses. The pools of water in the depressions
may add slightly to the humidity of the air in the immediate
vicinity; while the vegetation growing up from below and that
overhanging from the upper edge of the rock undoubtedly adds
to shade and contributes to a lower rate of evaporation. The

476 BOTANICAL GAZETTE [yuNE

rocks near the Des Plaines River, thrown out in straightening the
channel, have also been exposed for only a short time. It would
seem therefore that the recent exposure in some cases and the
distance from bodies of water sufficiently large to locally affect the
humidity may be two of the reasons for the poor development of

rupicole species. Another probably greater factor, at least for
Stony Island and Thornton, is the large amount of dust which
accumulates on vegetation, very effectually hindering photo-
synthetic work. At Stony Island there is much fine coal dust
from smokestacks and trains, as well as dust from factories.
At Thornton a large quantity of fine white dust thrown off from
the cement factory accumulates in a thin layer and forms almost
a crust, after light rains, on the foliage of all plants. There is less
dust at Lemont, where there is a somewhat better development of
mosses, but still much more than along Carroll Creek, which is
bordered only by forests and farm lands, and is far from any
factories. The later stages of succession on the rock outcropping
near Chicago, as stated before, have been greatly interfered with
by man. Evidently the change from pioneer conditions is ex-
tremely slow, and there is no development of true forest, so that
all moss stages beyond the pioneer are so far wanting.

Returning once more to the Carroll Creek ravine, in great
contrast to the Chicago region there is a narrow valley flanked
by steep rock walls upon which direct sunlight falls for only a short
number of hours each day. That this has much to do with the
lower evaporation and higher humidity is indicated by the more
mesophytic undergrowth and the greater luxuriance of mosses on
all undisturbed north facing slopes. Whatever moisture enters
the air through evaporation from the stream will be carried away
slowly, since such a valley is well protected from winds. Another
condition which also points to the moisture from the water as
an important factor is that the greater growth of mesophytic
mosses is found at places where the stream in its meanderings
comes close to the rock wall, either on the north or south side of
the ravine, and that the mosses are more luxuriant than in other
places with a similar exposure but farther from the water. An
additional cause may be found in the length of time in which snow

1920] TAY LOR—SUCCESSION OF MOSSES 477

remains upon these north facing slopes. In places sheltered from
the warm spring sunlight the snows melt slowly, and the moisture
soaks into the humus instead of running off rapidly, as it must do
on such an incline when the snow melts more quickly. It is well
known that in general the moss flora becomes more conspicuous
as we go north into the cold temperate regions. This condition
is comparable to that of the northern habitats where much of the
snow disappears under the action of sunlight and not of rains.
Since these slopes are exposed to a lower degree of insolation even
during the summer, the mosses are never subject to extreme desic-
cation. This cannot be true of the rock habitats which lie within
_ the Chicago region.

The great economic importance of such a moss covering is
demonstrated by the growth of seedlings of higher plants upon
the moss mat, which leads to the initiation of the tree associ-
ations. Herbaceous plants grow to maturity and produce seed
on moss covered rocks, with the roots obtaining nutriment only
from the decayed moss material. The slower growing tree seed-
lings can exist in a like manner for several years, by which time
their roots may be able to penetrate through the crevices or
between the rocks to the soil below. Mosses are very hygro-
scopic and quickly absorb water during rains, but give it up
slowly. Several days after rains water can be pressed from these
mosses even though seepage is not an important factor. In
addition to this is the immense value of a moss covering on rock
Slopes to conserve the water supply and prevent flooding of the
adjacent land along the lower course of the streams. The great
value of mosses in relation to the conservation of moisture and
their effect upon the soil was observed by OLTMANNs (8). He says:

A moss carpet acts as a sponge. A dense low carpet with countless capil-
lary spaces between leaves and rhizoids absorbs capillary and superficial water,
but obtains little or none by suction from soil and internal conduction. Con-
sequently living and dead carpets of moss imbibe and evaporate approximately
the same amount of water. A carpet of moss does not desiccate the soi
they dry it to a less degree than does other vegetation, and they protect ‘dry
easily heated soil from desiccation.

Evans and Nicwots (gs) also discuss the economic value of
mosses in such situations.

478 | BOTANICAL GAZETTE [JUNE

The moss successions on rock surfaces may be summarized
under two main heads: (1) There are at least four factors which
are of special importance in accounting for the better moss develop-
ment on rocks along Carroll Creek than in the Chicago region:
the greater humidity in the former place because of nearness
to a stream and lessened exposure; a lower evaporation rate
due largely to the fact that the rocks are sheltered from direct
rays of the sun for a greater number of hours each day; the slow
_ evaporation of the large quantity of water taken up by the moss
mat during the gradual melting of the snow, and consequent
lack of desiccation; and the freedom from atmospheric dust,
common about any large city, which tends to retard photo-
synthesis. (2) Mosses are of special value on a rock substratum,
as soil formers, to form a habitat for herbaceous plants, to initiate
the early tree associations, to conserve water supply and to prevent
floods by too rapid run-off, and to add to the aesthetic beauty of
the landscape.

RIVER BLUFF SUCCESSION.—Another somewhat xerophytic
habitat is that of a high river bluff as seen’ at Thornton, Illinois.
In this region Thorn Creek, a comparatively small stream, has
cut down much below its former level, resulting in drainage of
the adjacent land and a consequent lowering of the water table.
The trees along the bluff are deciduous and sufficiently scattered
to allow penetration of the sun’s rays, even during the summer.
Because of grazing there is no shrubby undergrowth. Here are
such mosses as Catharinea undulata, Leucobryum glaucum, Cera-
todon purpureus, Funaria hygrometrica, Polytrichum commune,
and Physcomitrium turbinatum, all of which are quite abundant.
All of these, except the last, are found in the neighboring swamp
forest. Catharinea, which is usually found only in the mesophytic
forest, is probably a relic from a previous period of greater meso-
phytism. Polyirichum, while often found in rather dry places,
seems usually to originate in mesophytic or even swampy habitats,
so that it also is likely a relic. Leucobryum and Funaria have @
wide range of habitat, and may be either relics from a more moist
condition, or pioneers on soil constantly becoming more xerophytic
at the surface. Ceratodon and Physcomitrium are doubtless sub-

1920] TAYLOR—SUCCESSION OF MOSSES 479

sequent species, as they are found only in somewhat xerophytic
species.

We have, therefore, a retrogressive succession indicated by the
moss flora, which is a mixture of relic or antecedent, typically
mesophytic species and the subsequent xerophytic forms. Such
retrograde successions are not uncommon wherever surface condi-
tions of soil water and exposure to evaporation have undergone
rather gradual modification.

HYDRARCH SUCCESSIONS

Under this heading have been included all successions originat-
ing in water or very moist habitats, with the exception of the moist
rock succession already described.

FLOODPLAIN SUCCESSION.—This succession was studied at
several points along the Des Plaines River, as at River Forest,
Riverside, on the east bank at Wheeling, and also along Carroll
Creek. The work has been of importance only for its negative
value in establishing the fact of almost entire absence of mosses
in such associations. Late in the season a few immature plants may
sometimes be found, but these seem never to reach maturity if
growing on soil, although a few well developed sporophytes may be
found on plants growing on logs above the high water level. The
true floodplain is subject to inundation during spring rains and
during high water at any season. A great quantity of fine alluvial
sediment is carried over the land and settles to the bottom with
the recession of the water, leaving a crustlike layer of variable
thickness over the ground and on any vegetation which may be
present. The moisture conditions, except during the flood period,
are favorable to spore germination; but the frequent deposit of
fine material, particularly at the period when the moss plants
would begin the season’s growth, seems to be sufficient to destroy
the ephemeral protonema which by any chance may begin to
develop. The immature plants found later in the season probably
come from late germination of spores which have escaped destruc-
tion or which have reached the floodplain from the surrounding
uplands after the spring inundation.

Evaporation on a floodplain is not excessive, and the available
supply of soil moisture is high, so that these two conditions

480 BOTANICAL GAZETTE [JUNE

cannot cause the absence of mosses. Competition with the abundant
herbaceous flora either in the spring or summer is only a secondary
cause, if worthy of consideration at all. If competition were a
prime factor, we should find somewhere in the floodplain succession,
either in the horizontal series from the water back to the upland
or in the series from the standpoint of time from the floodplain
formed by the younger stream as it begins deposition, up to the
old floodplain of the mature river which has nearly reached base
level, an association in which mosses take an important part. This
has not been observed on any of the floodplains under consideration.
It is not, therefore, a case of being crowded out by other plants,
but rather an inability to survive the unfavorable dynamic con-
ditions along a depositing stream, which are as effective in elimi-
nating mosses as was the active erosion of the earlier stages in the
stream’s development.

SPRING STREAM SUCCESSION.—At Otis, Indiana, and New Lenox,
Illinois, are numerous springs, the water of which is highly impreg-
nated with iron compounds. As the water comes in contact with
the oxygen of the air, bog iron ore is produced which builds up
mounds about the outlets of the springs until the water can no
longer force its way to the top for escape, and finds a lower exit
where there is less resistance to be overcome. Very frequently
numerous species of plants make up a large part of the foundation
structure of the tufa. Taking part in this tufa formation is 4
coarse moss, Brachythecium rivulare. The chemical substances in
the water penetrate the plant tissues which, as they grow old,
resist decay and form a porous rocklike mass. In the larger
stream forming the outlet of such springs at New Lenox are ,
several species of Amblystegium growing on submerged sticks and
stones, but these do not enter into the tufa formation. A few
other species, not typically water forms, grow on sticks which
emerge from the water. -

A somewhat comparable case of the formation of travertine in
the waterfalls of the Arbuckle Mountains in Oklahoma has been
described by Emic (4), in which-the two mosses Didymodon topha-
ceus and Philonotis calcare are the species involved. Still another
species, Cratoneuron filicinum, has. recently been collected by

1920] TAYLOR—SUCCESSION OF MOSSES 481

Cow es at Turkey Run, Indiana, where it is a common species aid-
ing in the tufa formation in the waters of similar mineral springs (11).

POND AND LAKE SUCCESSIONS.—The pond and lake successions
may be classed in two general groups based on the ecological
development. The early successions are represented in the
Chicago region by two subdivisions, the pine pannes examined at
Miller and the lagoons of Buffington and Long Lake, Indiana.
The later successions may be found in the swamp forests at Wilhelm
and Furnessville, Indiana, and Thornton, Illinois, and the bogs at
Mineral Springs and Hillside, Indiana.

Early stages of pond succession. —Pine pannes.—The pine
pannes are depressions among the dunes, so low that water which
seeps through the sand from the lake, or in this case partly from
the Grand Calumet River, reaches the surface or even may rise
above it. Some of the depressions may be quite dry during the
summer; others may have sufficient water to withstand ordinary
summer drought, and remain wet throughout the year. Surround-
ing the more or less circular body of water in the center of the
larger depressions is a border of pines of the same species as pre-
viously mentioned for the pine dunes. As a general rule we do
not find a typical pond flora even in the center, probably because
the quantity of water may be subject to great variation during the
year. Sedges and marsh grasses are common, especially near the
margin. Only one species of moss forms an extensive growth,
‘namely, Campylium stellatum. It may be entirely submerged in
the shallow water, but seems to thrive equally well along the edge
where it emerges, and, as a relic from a former hydrophytic condi-
tion, may even be found on the higher ground at the edge of the
tree zone. It is not a floating species in the pannes and is not
found in deep water, yet it is the same species which forms much
of the substratum. of the floating islands in the lagoons at Buf-
fington. While it cannot be considered as a tufa former, it aids
materially in filling up such depressions. On the higher land
among the trees other mosses are either absent or, if present, are
of the same species as already given for the early pine dunes.

Lagoons.—The lagoons at Buffington have been described in
the first part of this paper. The water is much deeper than in

482 BOTANICAL GAZETTE [JUNE

the pannes, and the vegetation varies from the submerged species
in deep water to the forests on the drier ridges. Floating in the
deeper lagoons and sometimes emerging in the more shallow ones
is a large quantity of Drepanocladus fluitans, D. aduncus, and
Campylium chrysophyllum, and perhaps other closely related
species. Around the margin of many lagoons are C. stellatum,
already mentioned for the pine pannes at Miller, and Bryum
ventricosum, which has also been found ‘at Long Lake and Pine
in much the same situations. In the larger lagoons are several
floating islands, of which C. stellatwm forms a large part of the
foundation. In the larger lakes about Chicago, such as Wolf and
Calumet lakes, the same marginal soil species of moss occur, but
so far none has been found floating or submerged in the deeper
water.

Wherever mosses appear, either floating or along the margin
of ponds, they aid greatly in the conversion of depressions into
land by promoting the advance of other terrestrial plants. There
seems to be little difference in the mosses of the pannes and lagoons,
except that which can be accounted for by the more shallow water
in the former, which may subject the plants to seasonal periods of
desiccation, and which would prohibit anything in the way of
floating mosses or of floating islands. In both cases it is quite
evident that mosses are an important class of plants in the early
stages of the pond successions.

Late stages of pond or lake succession—Swamp forests.—When
comparatively shallow ponds and lakes pass from the aquatic con-
ditions, the progress toward the later associations is by growth of
vegetation upon the bottom along the margin. Waste material
accumulates. In time the open water in the center is entirely
eliminated, and a swamp results, which, depending on local con-
ditions, may pass into a prairie where mosses take little part, oF
into a forest where they may be of prime importance. The Thorn-
ton and Furnessville swamps are illustrations of the latter type of
development in rather early stages, while that at Wilhelm gives a
later condition much more mesophytic. The first two are still
characterized by depressions and hummocks, which are rarely
encountered in the Wilhelm forest. Although humidity, shade,

1920] TAY LOR—SUCCESSION OF MOSSES 483

and other factors of environment do not differ widely in the three
areas, only five moss species have so far been found common to
all. These are Ceratodon purpureus, Mnium cuspidatum, and
Catharinea undulata on higher land or on logs, and Brachythecium
rutabulum and Amblystegium radicale in low wet places. All
except the first are mesophytic species. The Ceratodon occurs
rarely and then on sticks which are in rather dry locations in the
open or along the margin of the swamps. Sphagnum and Leuco-
bryum are found only at Thornton, the former growing on the
ground in depressions, and the latter on hummocks. Wilhelm far
surpasses the other forests in the total quantity of the moss flora.
Thuidium delicatulum grows abundantly on decaying logs and
occasionally on the ground, and is perhaps the most conspicuous
species with the exception of Mnium cuspidatum. Thuidium
recognitum and Anomodon rostratus are found in smaller quantities,
usually on logs or tree bases., Several of the very mesophytic
species, such as Climacium americanum and Rhodobryum roseum,
are common both on logs and on the ground. The shade is dense,
and decaying plant material forms a thick layer on the forest
floor. The moss display is of greater luxuriance than elsewhere
in the Chicago region and is a close rival of that of the Carroll
Creek ravine.

Bog forests.—The two bogs studied within the limits of the
region under consideration are the tamarack bog of Mineral Springs
and the Sphagnum bog near Hillside. Several typical associations
in the ecological development can be distinguished: the sedge mat,
shown at Mineral Springs; the shrub stage, well developed in both
bogs; and the tamarack tree association at Mineral Springs. An
additional division might be made of the Sphagnum moss associ-
ation at Hillside, but this is a slightly different line of development
rather than another ecological association.

As stated before, the bog successions are distinguished in
origin from the pond successions, in that they are formed on
sedge mats which grow out over the surface of deep lakes, form-
ing quaking bogs, which may remain in a very unstable con-
dition for many years. The first association to be found at Mineral
Springs at the present time is a mixture of bulrushes, cat-tails, and

484 BOTANICAL GAZETTE [JUNE

sedges, all of the early aquatic plants having disappeared. Mosses
are about equally conspicuous over the whole of the sedge mat,
and consist chiefly of six species, all long-stemmed and of some-
what upright habit of growth. They form a rather close packing
about the roots of the other plants. All are very hygroscopic and
grow partly submerged. The most noticeable is Calliergon cordi-
folium. The others are Campylium stellatum, C. hispidulum,
Drepanocladus aduncus, D. fluitans, and Brachythecium rivulare.

In the shrub association, where the shade is somewhat in-
creased, these species continue, but decrease in quantity. New
species do not seem to come in until the late shrub or early tree
associations which again show no distinct line of demarcation,
but merge into each other. It is here that we get the first develop-
ment of Sphagnum in the Mineral Springs bog. S. palustre occurs
usually in low wet depressions and has not formed a very extensive
growth either among the shrubs or in the tree association nies
it becomes more abundant.

Cooper (2), in his paper on the mosses of Isle Royale, discuises
the presence and absence of Sphagnum in bogs. He concludes that
Sphagnum comes in on the sedge mat following sedges of low growing
habits, which produce little shade and offer only slight obstruction to
the spread of the moss by vegetative growth. The inference is that
Sphagnum does not germinate in shade, although it may spread

into forests by vegetative growth from outside regions.
: This theory does not hold for the swamps and bogs of the
Chicago region. In the Mineral Springs bog the most common
sedges are relatively large and coarse. At Hillside the early sedge
stages are past, but the species still present are all tall and coarse.
In the former bog Sphagnum does not appear on the sedge mat;
in the latter S. recurvwm has in most places entirely replaced all
early associations. At Mineral Springs S. palustre begins in the
transition shrub-tree area, and becomes most abundant among
the tamaracks, where it is frequently found entirely disconnected
with any present Sphagnum region even in the transition associ-
ation. There is no evidence that it has spread from a less shaded
place of germination on the sedge mat, and there seems to be no
explanation of its presence other than that it has been able to-

1920] TAYLOR—SUCCESSION OF MOSSES 485

start under the shade of the trees and shrubs. North of the Mineral
Springs bog is a low, flat, sandy plain covered with shrubs and marsh
grass. The undergrowth is a compact mass of Sphagnum. In
many old lagoons which have reached the shrub stage or which have
a rank growth of swamp grasses, Sphagnum is growing in rather
dense shade, but whether it originated in shade or sunlight cannot
now be determined. Another case which is similar to that of
Mineral Springs is the presence of S. subsecundum in isolated
patches in the depressions of the Thornton swamp. There is no
connection whatever with outside Sphagnum areas. In fact, no
Sphagnum has thus far been discovered in the open regions around
the swamp. Many of these patches are in the interior of the
forest, and all are well shaded during the summer. It is quite
true that in both the Mineral Springs bog and the Thornton swamp
the trees are bare of foliage during the winter season, and there-
fore sunlight will reach the ground during the early spring. This
argument, however, can be applied equally to the sedge association,
where there is little shade from the coarse sedges until the new
growth has begun. In this region, therefore, it appears that
Sphagnum must be able to germinate under shade, and that it
may be present in forests without having reached these habitats
by vegetative encroachment from outside areas. This conclusion
is borne out by work done upon the germination of Sphagnum by
GrorcE L. Bryan. The results of the study have not yet been
published, and I am indebted to the kindness of W. J. G. LAnp of
the Botanical Department of the University of Chicago, under
whose direction the work was carried on, for permission to refer
to the results. BryAN made many careful experiments upon the
germination of Sphagnum spores under various conditions of soils
and sunlight, and found that germination occurred in all degrees
of sunlight and in darkness itself. Apparently there is some other
determining factor which controls the presence of this group of
mosses.

The tamaracks form a border about the bog. On the outer
margin they are being displaced by other bog trees, as Betula
lutea and Nyssa sylvatica. The tamaracks grow on hummocks, while
the depressions between them may be very wet or even filled with

486 BOTANICAL GAZETTE [JUNE

standing water. A large number of species of moss which have
not been found in the previous bog associations occur here, on the
ground, on sticks, or on logs. Calliergon cordifolium, the two
species of Campylium, the Brachythecium, and Drepanocladus
aduncus continue, often on partly submerged sticks. In slightly
higher situations, but on ground that is still very wet, are
Leucobryum glaucum, Climacium americanum, and Thuidium
delicatulum. With the exception of Leucobryum, these species
are also found on logs and sticks. Amomodon rostratus comes
in where there is less moisture, particularly about tree bases.
Here, as in the other mesophytic moss habitats, the soft hygro-
scopic mass of moss tissue forms a favorable place for the ger-
mination of tree seedlings and the seeds of other plants. As one
approaches the higher land adjoining the sand dune to the north,
the moss growth becomes less in quantity, but does not change
very much in species until the dune itself is reached.

In the Hillside bog, a large part of which has reached the
shrub stage, but in which there is much less water than at Mineral
Springs, Sphagnum recurvum has been, and in places still is, the
dominant vegetation. It must have reached a very luxuriant
development in the recent past, but is now on the decline. In
many places Aulacomnium palustre forms a second moss stage
growing on Sphagnum, and this is frequently accompanied by
_ Polytrichum commune. Cooper describes such an association in
the Sphagnum bogs on Isle Royale. The bog itself has not yet
developed the tree association, although with respect to moisture
conditions it has advanced much beyond the bog at Mineral Springs.
It is surrounded by climax beech-maple forest, and it is quite likely
that this will be the fate of the bog if left to nature’s influence.
In the adjoining beech-maple forest Catharinea undulata is again
the only moss of any prominence.

Table II represents the hydrarch succession from open water
of lagoons and ponds to the climax forest. Once more the great
importance of pioneer mosses in the advancement of the higher
plant associations is shown. The economic value of shallow
ponds is slight; while on the other hand they may be very injurious
in that they harbor larvae of insects, harmful to man, so that the

1920] TAYLOR—SUCCESSION OF MOSSES 487
elimination of such swampy regions may be very desirable. By
the filling up of. depressions the area may be made productive
either as prairie or forest. The poorly drained deeper ponds are
probably as little to be desired from an economic standpoint, since
the water will not support the life of aquatic animals of commercial
value. Consequently any natural agency which will further the
change from hydrophytic to mesophytic conditions will add to the
number of acres of productive land reclaimed from a state of
total non-productivity, and also lead to better health conditions
for the inhabitants of the surrounding country.

TABLE II

PRESENCE OF MOSS SPECIES IN ASSOCIATIONS OF HYDRARCH SUCCESSION

Species

Open water

Sedge mat

Tamaracks

Swamp forest

Beech-maple

Amblystegium — ‘
Anomodon rostratus. .

Drepanocladus aduncus. :

Drepanocladus fluita

Dicranum scoparium. . ..

Entodon cladorrhizans.. .
la

ey

dat
Polytrichum commune...

uidium delicatulum. .
uidium recognitum

slew ew ee en ee

ale ee we ee ewe

oe

roa ah ae ey oe ee i

oe ee

es eee ee ee

ee

Se a a

SS ce ee ee

eee ewww eae

ee

ee

obryum roseum. ..
Shepsntion ual haldanianum. .

ee

66 4b tee eo

+ 46 V8 886. 0 8

ee a

ee er)

ee

ee

oe gece eee

ee a ee ed

rr

a Ba-ha-la~Ea-hacla-ha-hae]

Se a ee a ee

Co ee ee ee

aw He-la~lan Bala Bar ka~las)

Cee, ee 8 86
ee ee ee
ee ee ey
a
ee a ee
ad Se 8 ede Se

ee

e H6) eee ew Rae
eC ee ee ee ed
ae ee a eee)
see ee eeeee
nee ee 8 8 6 ee
see ee we woe
er er ee ee
ee ee

a

The pannes about Miller are mostly of recent origin and are not

within easy reach of other habitats of aquatic mosses. This may
account for the fact that the few species are present. The mosses
found growing in all of these ponds, so far as observed, propagate
vegetatively only, or with very rare spore production, thus virtually
prohibiting their spread into distant ponds except when carried by
birds or other animals. As previously mentioned, these mosses must
be able to make a good recovery after periods of desiccation, and
must also be able to resist covering to some extent, as these pannes

488 . BOTANICAL GAZETTE [JUNE

are subject to occasional dry seasons and frequent deposit of sand.
The presence of the mosses soon leads to accumulation of humus
over the sandy bottom and initiates the growth of semihydrophytes.

In the lagoon region is a far more extensive pond area, both
as to actual number of ponds and variation in ecological develop-
ment, caused by depth and size as well as by age of the individual
lagoons. The chance for transfer of mosses from one pond to
another is much better; the variation in depth permits the growth
both of floating and fixed species, while the greater age has allowed
time for accumulation of more humus, which leads to the introduc-
tion of still other species, as well as perhaps a more luxuriant
growth of all. With these conditions comes the rapid advance of
the shrub and forest or prairie successions. In the swamp forest
the moss flora becomes increasingly a dominant factor in humus
accumulation as the ecological succession advances toward the
climax, but begins to decline with the close approach of the heech-
maple association. This appears to be a result both of competi-
tion with other ground flora and of the smaller supply of available
water near the surface.

Very little work has been done in determining conditions for
plant life in the bogs, but from the xerophytic structures of many
bog plants, and the shallow root systems of the trees, COWLES
concludes that, while moisture is plentiful, the chemical content
of the water is such as to have a toxic effect upon the root develop-
ment of plants, and to prevent absorption of water to a great
extent. In other words, this is a physiologically xerophytic habitat
for seed plants. It is not known how far this may influence the
development of mosses; that it is not very injurious is proved by
the great abundance of some species, such as Sphagnum. On the
sedge mat the shade may be considerable when cat-tails are
abundant, but the sun’s rays reach the ground more directly than
in the forest. The humidity near the ground is probably greater
than among the trees, but evaporation at times is also much greater.
The mosses occupy the small spaces around the roots of the fen
plants and often cling closely to them, forming a packing between
the stems, but there are no large masses. In some places there is
a luxuriant growth of marsh forget-me-not and other species of

1920] TAYLOR—SUCCESSION OF MOSSES 489

low growing seed plants which nearly smother out the mosses.
The increase in shade and possibly other conditions in the late
shrub stage and early tree association apparently are unfavorable
for most of the old herbaceous species, and new ones. have not
taken their places, so that there are large areas unoccupied by such
ground vegetation. As in the pine dune, so also here we may have
toxicity produced by decay of conifer needles. This probably does
not greatly retard the moss development, although it may account
in part for the change in species. With herbaceous plants, on the
other hand, it may result in almost total elimination. The rapid
increase of quantity and number of species of moss in the early tree
association, therefore, is directly related to these environmental
conditions. The greater shade and lower temperature are both
more favorable to moss growth, and added to these is the lack of
competition with other plants.

As the tamaracks are replaced by deciduous trees, the mosses
give place to herbaceous seed plants. The chemical condition of
the subsoil changes, more humus accumulates, moisture and
humidity decrease. The mosses now are crowded out of their
former locations until, with few exceptions, they persist only on
sticks, logs, and tree bases, and we find in their place many ferns
and seed plants. Competition seems to be the great cause of the
elimination. Some general conclusions regarding the pond and
lake successions of mosses are as follows.

Very few mosses appear in the pannes, but those which are
present are coarse and aid in filling up the depressions. The
lagoons are favorable habitats for floating species, while other
mosses are abundant along the margin. Both produce material
which is added to the muck on the bottom and which provides
nourishment for other plants. Still other species assist in the
formation of floating islands. In the bogs a few species of semi-
aquatic mosses appear in the early fen stage in considerable quan-
tities. There is a slight decrease in quantity in the shrub stage.
A marked increase in quantity and number of species is evident in
the early tamarack association and continues until the tamaracks
are replaced by deciduous trees, making the tamarack the domi-
nant moss association. In the later deciduous association there is

490 BOTANICAL GAZETTE [JUNE

a continuous decline in the moss flora until the climax beech-maple
forest is reached. Competition with other plants seems to be the
determining factor as the successions advance beyond the semi-
hydrophytic.

Conclusions

1. In the successions on sand, mosses are most abundant, both
in number of species and in total quantity in the stage; in which
they first become very noticeable, the pine stage; and they decrease
through the early oak stages to either the oak or the beech-maple
climax.

2. In the swamp and bog successions the greatest dominance
of mosses is found usually in the swamp or bog forest association,
which may or may not directly precede the climax.

3. The mosses found in running spring water and in stagnant
water are of different species, but nearly all belong to the same
family, the Hypnaceae.

4. The succession on floodplains is unimportant because of
constant deposit of sediment over the germinating mosses.

5. Mosses are among the highly important pioneer plants on
bare rock surfaces, and continue abundant far into the forest
association,

6. From an economic standpoint mosses are of the ante
value in several respects. They are soil formers and provide
favorable habitats for germination of higher plants. They assist
largely in forming the surface mat over deep lakes and in filling
up shallow bodies of water. They may take part in building
up rocklike substances, as tufa. They help to make up floating
islands on which higher plants may grow. They conserve moisture,
and give it up slowly, thus aiding in the prevention of disastrous
floods in the. surrounding regions. They prevent erosion of clay
or sand surfaces.

1920] TAYLOR—SUCCESSION OF MOSSES 491

LITERATURE CITED
< Buavw, E. Lucy, The vegetation of conglomerate rocks of the Cincinnati
region. Plant World 20:380-392. 1917.
., Ecological succession mosses on Isle Royale, Lake
Superior. Plant World 15:1
she H, C., The plant nas of “Chae and vicinity. Chicago. °

N
ie
S
a}
eI
Se
=
Ln

ie
.

Eat Fas ., Mosses as rock builders. Bryologist 21:25-27. 1918.
, A. W., and Nicuots, G. E., The bryophytes of eee
Hadid. 1908.
6. FuLter, G. D., Evaporation and soil moisture in relation to the succession
of plant associations. Bort. GAZ. 58:193-234. 1914.
7- Grout, A. J., Mosses with a hand lens and microscope. New York.

on
. .

1905.

8. Orrmanns, F., Uber die Wasserbewegung in der Moospflanze und ihrer
Einfluss auf die Wasservertheilung im Boden. Cohn’s Beitrage 4:1887.

9. SALISBURY, R. D., and ALDEN, Wa. C., The geography of Chicago and its
environs. Chicago. 1899.

10. SHELFORD, V. E., Animal communities in temperate America. Chicago.
1913.

tr. Taytor, ARAVILLA M., Mosses as formers of tufa and of floating islands.
Bryologist 23:38-39. rgr9.

12. Utricu, F. T., The relation of evaporation and soil moisture to plant
succession in a ravine. Bull. Ill. State Lab. Nat. Hist. 12:1-16. 1915.

13. WARMING, Euc., Lehrbuch der dkologischen Pflanzengeographie. 2d

' German ed. 121-122. 1902.

14. WARNSTORF, C., Kryptogamenflora der Mark Brandenburg 1: 20-25.

1903.

OVULIFEROUS STRUCTURES OF TAXUS CANADENSIS .
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 267
A. W. DUPLER |
(WITH PLATE. XXIII AND SIXTY FIGURES)

Introduction

Following a recent paper (13) in which the writer gave a descrip-
tion of the staminate structures of Taxus canadensis Marsh., this
paper deals with the ovuliferous structures, namely, the primary
shoot, the secondary shoot, and the ovule, describing both the
development and vascular features, together with a discussion of
the morphological questions raised by these. structures. The
purpose in this investigation was twofold: (1) to compare T. cana-
densis with the European T. baccata, and (2) to look for new evi-
dence bearing on the morphological problems of these structures
in.the genus. While no pretense of finality is made in this con-
nection, it is thought that some additional evidence has been
secured bearing on these problems. Since the female gametophyte
has already been described (12), only such reference is made to it
as may be necessary. Fora statement as to materials and methods,
the reader is referred to previous papers (12, 13). |

Historical

Taxus has engaged the interest of botanists for a long time, the
ovulate features, the gametophytes, and the early embryogeny
especially receiving attention. The literature dealing with the
ovulate structures is quite extensive, much of it being found in
connection with descriptions and discussions of other conifers, and
is based almost entirely upon J. baccata, very little dealing spe-
cifically with T. canadensis. The two forms are similar (6), and
much which has been written will apply equally well to both forms.
It would be impracticable to include a complete summary of all that
has been published on the subject, a a See summary sufficing,
Botanical Gazette, vol. 69] [492

1920] DUPLER—TAXUS CANADENSIS 493

more complete references being available in the accounts of
- STRASBURGER (35), RApAtsS (24), and WorspDELL (39).

The earlier work was based largely on external features, and
attempted to homologize the structures with those of the angi-
osperm flower. This attempt seemingly persisted much later with
Taxus than with most other conifers, the gymnospermy of Taxus
not being quite so soon recognized as in other forms. The bulk’ of
the literature deals with the more theoretical questions, the actual
descriptive work not being so extensive. The discussion of the
_ literature will be presented in the text of the paper, in connection
with the several topics, in this way avoiding repetition and pre-
- senting each topic in more complete form.

Ovuliferous bud

As previously pointed out (13), three types of buds are formed
in the axils of the leaves of a current season’s shoot, namely, vegeta-
tive, staminate, and ovuliferous. The differentiation of the last is
first recognized by the appearance of the rudiment of a secondary
axis in the axil of one of its uppermost scales (fig. 1), this rudiment
appearing early in July. The ovuliferous bud begins early in the
spring, as a conical rudiment in the axil of a young leaf, shortly
after the beginning of the growth of the vegetative shoot, forming
usually nearer the tip than the staminate buds. STRASBURGER
(36) found the first differentiation of the ovuliferous bud in
T. baccata to occur about August 1. The structure can be dis-
tinguished by external features with certainty only when the
ovule has reached such size as to protrude beyond the scales,
usually not until spring. JAGER (15) says that the ovuliferous bud
of T. baccata is evident about February 1, being slightly yellowish,
and the vegetative bud being reddish brown; but this is hardly a
safe criterion, owing to color variations.

Primary shoot

GENERAL FEATURES.—The ovuliferous organ in Taxus consists

of two structures: the primary ovuliferous branch, or, as it is more

generally known, the primary shoot; and the secondary shoot
on which the ovule is borne. The primary shoot arises directly

494 BOTANICAL GAZETTE [JUNE

in the axil of the leaf, and, as STRASBURGER (35) pointed out for
T. baccata, begins with two transverse scales, following which are
a number of scales in spiral order, in the axil of one (or two) of

base; fig. 5, median longitudinal section of primary shoot, secondary shoot, and
ovule, such as fig. 4; figs. 1, 2, X24; fig. 5, X17.

which the secondary shoot (or shoots) arise. The scales of the
primary shoot are very similar to the scales of the staminate

1920] DUPLER—TAXUS CANADENSIS 495

strobilus already described (13), having very thick epidermal walls,
especially on the outer surface, stomata on the inner surface, and
rather large air spaces. They are brownish and lack chlorophyll.

During its first season the primary shoot is a dwarf branch of
limited growth, and the development of the secondary shoot

results in its tip becoming pushed aside (fig. 2) and remaining

dormant for a time. Externally this gives the appearance of a
single structure with a terminal ovule, a situation which may
explain some of the earlier views as to the position of the ovule.
VaN TIEGHEM (37) apparently was the first to point out this
behavior of the primary axis. According to SCHUMANN (31), and
also PILGER (23), the primary axis ends blindly, and the so-called
tip of the primary shoot is the knob of a reduced side shoot which
may at times grow out to form a second secondary shoot. When
this occurs the primary axis may form a short knob between the
two secondary shoots. This view does not agree with the facts and
has received but little support.

SECOND SEASON’S GROWTH.—The tip of the primary shoot —
remains dormant until the next spring, when its growth is renewed,
resulting either in its continuation as a dwarf structure, as in the
first season, or in its growth as a leafy shoot, like that from the
ordinary vegetative bud, a fact first noted for T. baccata by STRAS- —
BURGER (35). This leafy shoot may bear only a few small leaves
(fig. 3) and develop no further during the second season, the sub-
sequent behavior of such small shoots not being known. It also
may develop as an ordinary leafy branch, differing in no way from
other leafy branches except in bearing the secondary shoot at
its base (figs. 4, 5), and, like any other vegetative branch, bearing
vegetative and reproductive buds of the next season. Occasionally
the primary axis remains dormant as a vegetative bud for a season
or more. In such cases the reproductive nature of the first season
can be told only by the scars of the old secondary shoot (fig. 6).
Normally, however, the primary shoot continues its dwarf and
reproductive character for the second and later seasons, producing
a few scales as in the preceding season, with one or two new sec-
ondary shoots on the new growth. It has been generally assumed
that the primary shoot produces fruiting structures for only one

496 BOTANICAL GAZETTE [JUNE

season, and that the maturity of the secondary shoot with the
ovule results in the death of the primary shoot as well. This is
not the normal situation, as usually only the secondary shoot
with the ovule drops from the primary shoot, which remains in the
axil of the leaf, a branch scar showing the place of detachment
at the secondary shoot from the primary shoot (fig. 6). Detach-
ment of the secondary shoot is probably accomplished normally
by the formation of an absciss layer across the base of the shoot.
The region of abscission is marked by a narrow layer of platelike
cells, rich in protoplasm, outside of which is a layer (5-6 cells wide)
of cork tissue, and whose outer border consists of radially elongated
cells which form a conical cap to the scar (fig. 7). When collec-
tions of T. canadensis for this study were first begun, in the autumn
of 1913, it was noticed that ovulate buds were to be found on older
as well as on the current season’s growth, as has since been pointed
out for T. baccata by Miss AAs (1). This is not due to dormancy
of buds which had failed in development, as might usually be
assumed, but to the persistence of the primary shoot year after
year, producing one or two new secondary shoots each season.
This renewal of growth is contemporaneous with that of the
primary shoots of new branches, beginning early in the spring,
although not becoming recognizable externally until later in the
summer, when it can be distinguished by the slight projection which
appears at the base of the secondary shoot (fig. 8). Growth is
slow, and by the middle of July is arrested, as in previous seasons,
by the growth of the new secondary shoot (fig. 9). As these
observations show, the primary shoot is a persistent structure and
may produce secondary shoots season after season, or become a
leafy shoot, the situation being evidence against regarding the
primary shoot with its spared shoot as representing a compound
strobilus.

TERMINAL PRIMARY SHOOT.—Several cases were found in which
the primary shoot was a terminal structure of the leafy branch
(figs. 10, 11), the terminal bud having developed as a primary
ovuliferous structure, bearing a secondary shoot. That this may
continue to function as a primary shoot for more than one sea-
son is shown by the presence of a secondary branch scar a little

Fics. 6-11.—Fig. 6, long section of primary shoot showing scars of secondary
shoots of two previous seasons; primary axis remaining dormant, not producing
secondary shoot the season collected; 24; fig. 7, detail section through scar (note
shaded abscission layer and corklike wound tissue external to it); Xr14o0; fig. 8,
primary shoot with mature ovule and projection at base of ovule showing external —
appearance of a normal second season’s growth of primary shoot; fig. 9, longitudinal
section of primary shoot showing half-grown ovule of current season and young ovule
of next season (primary axis tip shown below younger ovule); X17; fig. 10, terminal
pri shoot; fig. 11, longitudinal section of terminal primary shoot (leaf base
shown at lower end of figure; note branch scar, left by secondary shoot of preceding
season, and that primary axis tip has begun growth for third successive season);
aril shown at base of ovule; X17.

498 BOTANICAL GAZETTE [JUNE

distance below the tip of the primary axis (fig. 11), in which the
tip of the primary axis has also begun its renewal of growth for
the third successive season. No case was found in which it was
known that a terminal primary shoot later became functionally
vegetative; but in view of the occasional behavior of the primary
shoot as a leafy shoot, it is very possible that a terminal primary
shoot may again become vegetative in function.

YS\ OSL

13 14 15

©) —s a)
16 (6) 17 18

Fics. 12-1 ao as at different levels showing at supply from leafy shoot
to primary shoot: fig. 12, vascular cylinder of leafy shoot; fig. 13, trace to fertile leaf
and formation = vascular strands to primary shoot; et 14, apap strands for
primary shoot separated from main cylinder, showing branch gap; fig. main axis
cyl closed with primary axis cylinder and bundle of fertile leaf pies removed;
fig. 16, primary axis cylinder closed; figs. 17, 18, bundles to lower scales of primary
shoot, first pair being normally transverse, as — remainder usually spiral with
Reinet a second transverse pair, as in fig. 18 .

VASCULAR FEATURES.—STRASBURGER (35) was the first to
describe the vascular supply of the primary shoot of 7. baccaia,
and it is essentially the same in T. canadensis. The primary shoot
receives two bundles from the axis of the leafy shoot (figs. 12-1 5)-
These bundles meet at their edges (fig. 16) and form a complete
vascular cylinder, which then gives off traces to the lateral scales
(figs. 17-20). At the level of the fertile scale the cylinder organizes

1920] DUPLER—TAXUS CANADENSIS 499

into two large bundles, which pass into the axis of the secondary
shoot (figs. 19-22), only a very weak vascular supply passing into
the arrested primary axis tip. If there are two secondary shoots,
each receives a pair of vascular bundles (figs. 23-27). Should
the primary axis grow out into a leafy shoot the next season, a
normal vascular cylinder develops, and the vascular supply to the
secondary shoot has the usual features of an axillary. structure
(figs. 28-30). The normal continuation of the primary shoot in
its dwarf character during the next season results in a vascular
supply to the new growth, similar to that of the preceding season.
The vascular tissue of the new growth develops in connection with
the bases of the bundles which passed to the secondary shoot of the
preceding season, so that a series of sections shows a continuous
vascular strand throughout the entire secondary shoot axis, broken
by the small scale traces and by a wide gap at the level of the
secondary shoot scar, where the bundle supply to the secondary shoot
had passed off from the main axis. This gap, however, does not
have the ordinary features of a branch gap, being really the leaf
gap of the fertile scale subtending it, the bundle supply of the
detached secondary shoot being in lateral connection with the main
axis at all points, and not separated from it as in ordinary branch
gaps (fig. 32; cf. figs. 13, 14). The previously arrested and rudi-
mentary condition of the axis tip accounts for this behavior. The
xylem portion of the cylinder is relatively narrow, growth being
slow and uniform. Shoots more than one year old do not usually
show any growth ring excepting in the region of the secondary
branches of the preceding seasons, where the limit between the
xylem of the first and second season’s growth is very distinct.
The xylem is endarch in the cylinder, but in the scales centripetal
wood may appear, although the scale traces in general are quite
short, frequently ending in the base of the scale.

MORPHOLOGICAL NATURE.—The morphological nature of the ©
primary shoot has been the subject of some question. It seems
clear that in Taxus the primary shoot is to be regarded as a vegeta-
tive shoot of limited growth, persistent for an indefinite period,
producing secondary fruiting shoots season after season, as a dwarf
shoot functioning only in this way. It may become a vegetative

500 BOTANICAL GAZETTE ; [JUNE

32

Fics. 19-33.—Figs. 19-22, series showing bundle supply from primary shoot to

_ Secondary shoot, also transition from normal primary cylinder (fig. 19) to organiza-

.

ntinuous with primary lind: for normal
axillary structure); fig. 33, through branch scar (with crossed lines), and fertile
scale; X24.

1920] DUPLER—TAXUS CANADENSIS 501

shoot of unlimited growth, however, then having both the vege-
tative and reproductive possibilities of any other branch. The
occasional behavior of the terminal bud in becoming a dwarf
primary shoot recalls a similar behavior in Ginkgo, although one
must not infer too much as to relationship on this account.

Secondary shoot

GENERAL FEATURES.—The primordium of the secondary shoot
first appears as a lateral structure in the axil of one of the upper-
most scales of the primary shoot (fig. 34), soon becoming conical
(fig. 35). It is generally stated that the terminal scale is the fertile
one, but one or more small scales usually appear above the fertile
one, as was pointed out in T. baccata by VAN TreGHem (37). Dif-
ferent writers have assigned definite scales of the primary shoot
as the fertile one in T. baccata, VAN TreEGHEM claiming the eleventh,
STRASBURGER (36) the eighth or thirteenth, and Pricer (23) the
seventh; but this varies and is of no special importance. Fre-
quently two of the scales are fertile and two secondary shoots occur,
the tip of the primary shoot then appearing between them (fig. 36).
In Torreya there are usually two secondary shoots on a primary
shoot, but STRASBURGER’s account that in rare cases in Torreya
the primary shoot behaves as a secondary shoot, and bears a third
ovule above the two secondary shoots, does not apply to Taxus.

The rudiment of the secondary shoot develops rapidly, producing
the three pairs of decussate scales*in rapid succession, the cyclic
arrangement of which is in contrast with the spiral arrangement of
the scales of the primary shoot. The first pair stands transversely
to the fertile scale. VAN TrecHem held that while the scales are
decussate there is an indication of a spiral tendency, a view
necessary to his theory that the ovule is an axillary structure of
the sixth scale of the secondary axis. Practically all investigators
agree as to the decussate nature of the scales, as there seems to be
no basis for regarding the scales as having a spiral arrangement.
The scales of the secondary shoot are considerably larger than
those of the primary shoot, and contain chlorophyll, the outer
epidermis being heavily cutinized, and stomata occurring on the
inner surface. In the early stages these scales protect the young

502 BOTANICAL GAZETTE [JUNE

ovule, but shortly before pollination the tip of the ovule protrudes
from between the scales, and with its development they become
relatively less conspicuous.
OVULE
HistoricAL.—The ovule of Taxus has been the subject of con-
siderable discussion among botanists. The earlier taxonomists,
such as LINNAEUS (17) and Jussteu (16), regarded the ovule of

yD

Fics. 34-42.—Fig. 34, long section of primary shoot showing lateral axillary rudi-
ment (r) of secondary shoot; fig. 35, older stage, rudiment become conical; fig. 36,
rudiments of two secondary shoots, primary axis tip between; fig. 37, axis tip of
secondary shoot showing bulge indicating beginning of integumentary zone; fig. 38,
older stage showing integumentary zone more distinct and differentiation of arche-
sporium (for detail see fig. 61); fig. 39, older stage showing young integument and
position of sporogenous tissue (inclosed by dotted line); fig. 40, young ovule about
time of pollination, showing barrel-shaped integument and large open micropyle;
figs. 41, 42, older ovules and closure of micropyle by plug tissue (for details see figs. 66,
67); te 34-39, X80; figs. 40-42, X36.

1920] DUPLER—TAXUS CANADENSIS 503

all conifers as a pistil. TRew’s observations, in 1767, that the
ovule of conifers receives the pollen directly, the representation
of TreEw’s observations by TARGIONI-Tozertt in 1810 (RADAIS 24),
and Brown’s (6) announcement of gymnospermy introduced a
fertile topic for debate. For a time these newer views met strong
opposition, R1cHARD (25), for instance, declaring that there are
no plants with naked ovules or without an ovary, and holding that
the ovular integument was the perianth and the nucellus the pistil
of the flower. BatLLon (2) was also a vigorous opponent, holding
the ovule to be a 2-carpel ovary with a single orthotropous ovule.
PARLATORE (22), SPERK (34), with others, and even STRASBURGER
(35) for a time also held to the ovarian theory of the ovule.
Another group, among whom were SCHLEIDEN (29), A. BRAUN (5),
SACHS (26), and others, accepted BROwNn’s view as to gymnospermy.
STRASBURGER later accepted the same interpretation, and the
question of the gymnospermy of Taxus has been generally accepted.

The morphological position of the ovule has not been so
definitely settled, and it may yet be regarded as an open question
whether it is a lateral structure, foliar in origin and only secondarily
terminal, or a true terminal structure, unrelated to the scales in
its origin. The first of these views depends upon the assumption
that the ovule in gymnosperms must always be related to sporo-
phylls, present or suppressed; the second that the ovule may arise
from the axis itself, independent of lateral organs. Among the
early workers SCHLEIDEN (30), SCHACHT (28), and others regarded |
the ovule as terminal to the branch. On the other hand, Don (11),
Caspary (7), and others held to the foliar origin of the ovule.
Van TiecHEM (37), using the anatomical method as a basis of
interpretation, concluded from the orientation of the bundles that
the ovule represents the first and only leaf of a shoot of the third
order in the axil of the sixth bract of the secondary shoot, a view
also accepted by STRASBURGER (35). SACHS (26) regarded the
ovule as secondarily terminal, the bract nearest the ovule playing
the réle of the carpel, but later (24) changed his opinion, admitting
the ovule to be terminal and a modified stem. STRASBURGER also
abandoned his earlier position and held that the ovule is strictly
terminal on the axis tip, that no relation to the last pair of scales

504 BOTANICAL GAZETTE [JUNE

oe,

can be found, and that there is no ground for VAN TIEGHEM’Ss view.
Macunvs (18), pointing out the cauline origin of the ovule in Nazas,
spoke of it being similar to the situation in Taxus, in which he
regarded the ovule as terminal. Later workers have more generally
accepted the terminal nature of the structure. CELAKOvSKY (8)
held that the sporangium is terminal to the axis. WorsDELL (38)
accepted and championed this view, stating that “‘anatomy points
clearly to the fact that no axial foliar appendage of any kind exists
upon which the sporangium is inserted, the cylinder of the axis
being directly continuous into the base of the sporangium.”
JAGER (15) speaks of the nucellus in T. baccata being formed by the
vegetative tip of the secondary shoot. Miss AAsE (1), in a recent
study of this problem, points out that the vascular supply to the
ovule is ‘‘contrary to what should be expected” for an axillary
structure. She also suggests the possibility of a fusion of sporo-
phylls to form a single structure.

For a solution of the problem two groups of facts can be used
directly, the origin and development of the ovule, and its vascular
‘supply; the latter will be treated in connection with the vascular
features of the secondary shoot as a whole. There are no known
abnormalities with which one can compare the normal situation.
Torreya apparently presents a similar situation, and thus gives no
additional line of evidence.

ORIGIN OF OVULE.—The first indication of the ovular nature
of the end of the shoot is the beginning of the integument as a ring
around the tip of the axis (figs. 37, 38), and the axis tip itself becom-
ing the nucellus, as claimed by both StrrasBuRGER (36) and JAGER
(15) for T. baccata. There is nothing in the position of the ovule
to indicate that it is a lateral structure, and so far as its ontogenetic
origin gives'a clue one must conclude that the ovule is strictly
terminal, cauline in origin, and unrelated to any of the scales. If
the scales represent sterile sporophylls phylogenetically, as is
most probable, their sporophyll character has been completely
abandoned and the axis itself becomes the sporangium, as in some
of the angiosperms, where cauline ovules are not uncommon.
That the vascular features sustain this view will be indicated
later.

1920] DUPLER—TAXUS CANADENSIS 505

MEGASPORANGIUM.—In T. baccata STRASBURGER (36) pointed
out the hypodermal origin of the archesporium, describing it also
for Larix europea. In T. canadensis the sporogenous tissue is
also hypodermal in origin, the archesporium becoming differentiated
very early in the development of the nucellus while it is yet cone-
shaped and the integumentary zone in a rudimentary: condition
(figs. 38, 61). It may consist of a single cell or a small plate of
cells. The periclinal division of the archesporium results in the
primary wall cell and the primary sporogenous cell (fig. 62). The
wall cell, together with other adjacent cells of the nucellus, divides
repeatedly by periclinal divisions, building up a considerable mass
of tissue between the sporogenous tissue and the epidermis, the
cells of this tissue being in radial rows, at the inner ends of which
are the sporogenous cells (figs. 63-65). Morphologically this is
the outer portion of the many-layered wall of the megasporangium,.
and together with the epidermis constitutes the upper portion of the
nucellus. The later development results in a considerable mass
of sporogenous tissue (fig. 64), out of which one or more cells func-
tion as megaspore mother cells (fig. 65), as pointed out in my
previous paper (12). While I have no preparations showing divi-
sions of the primary sporogenous cells, the amount of sporogenous
tissue present indicates that this takes place, contrasting with the
situation in which the primary sporogenous cell functions as the
megaspore mother cell, as is probable in most conifers.

GROWTH OF NUCELLUS.—By the formation of the integument
the nucellus becomes limited to a knob, at first conical; but with
the development of the megasporangium it soon becomes rounded.
From the growth of the wall, as just described, there develops a
considerable mass of tissue above the sporogenous tissue. At first
this tissue seems to be uniformly meristematic, but later division
becomes confined to the inner portions, the outer cells and the
epidermis becoming radially elongated. I was not able to find any
actual periclinal divisions of the epidermis, but the position of the
cells in the layers next to the surface (fig. 65) would indicate such
divisions as STRASBURGER (36) found in the development of the
nucellus of T. baccata, giving a several-layered epidermis. The
nucellus, therefore, is composed of two morphological entities,

506 : BOTANICAL GAZETTE [une

the epidermis and the sporangium. The nucellus increases in
diameter by anticlinal divisions of both epidermis and sporangium
wall. Basal growth takes place also, so that the sporogenous
region becomes situated in the focal center of the oval nucellus
(figs. 40-42). From this time greater meristematic activity occurs
in the peripheral regions contiguous to the line where nucellus and
integument meet, resulting in the enlarged base of the nucellus.
The tapetal function of that portion of the nucellus immediately
surrounding the developing gametophyte, and the digestion of the
nucellar tissue in the enlargement of the endosperm have already
been described (12). The growing endosperm presses upon and
stretches the nucellus so much that at maturity it is but a thin
layer surrounding the endosperm.

A feature of interest is the extent of the boedons. of the nucellus
from the integument. In the earlier stages of development the
two structures are entirely free from one another, a condition which
persists until about the time of fertilization. The chalazal region
now becomes the center of great meristematic activity, resulting
in the development of the aril and the zonal growth of nucellus
and integument as a united structure, so that at maturity the
freedom of the nucellus from the integument is only partial.
HoFrMEISTER’S (14) statement that in 7. baccata the separation
between the “nucleus” (nucellus) and the integument extended
entirely to the base was most probably based on young ovules.
Freedom of nucellus and integument occurs in Paleozoic seeds
belonging to the Cordaitales, such as Cordianthus, and is perhaps a
primitive feature retained by most modern gymnosperms only
during the early stages in the development of the ovule. That
freedom of the two structures should persist longer in some forms
than in others is not surprising, and has been regarded as having
morphological significance. Taxus, Torreya, and some others are
alike in retaining this feature for some time, the relative amount
of it being correlated somewhat with the size of the seed, basal
growth of the ovule being more extensive in some forms than in
others. OLIVER (21) has called attention to the basal intercalary
growth of the ovule in Torreya, which results in raising both
nucellus and integument. He also suggests that the lower portion

1920] DUPLER—TAXUS CANADENSIS 507

of the seed is phylogenetically younger than the apex, where nucellus
and integument are free from one another, introducing a problem
already suggested by STRASBURGER (36) as to the real limits of the
morphological ovule.

INTEGUMENT.—The development and structure of the integu-
ment of T. baccata have been described rather completely by
*STRASBURGER (35), BERTRAND (3), and JAGER (15), and are not
different in T. canadensis. The integument arises as a zone of
meristematic tissue surrounding the young nucellus (figs. 37-39).
Uniform growth in the entire zone results in a cylindrical, barrel-
shaped integument surrounding the young nucellus (fig. 40), and
extending some distance above it. At first the integument is
uniform in thickness, six or more cell layers thick. The integu-
ment is 2-lipped from the early stages in its development, the lips
alternating with the upper pair of scales. This feature has led
some workers to interpret the integument as two carpels, and others
as the fusion of two sporophylls. This 2-lipped character persists
to the mature seed, but probably has no more morphological
significance than has a similar and more pronounced feature in the
ovules of many other conifers, especially the Abietineae, in which

no foliar significance is attached to this character.

Up to the time of pollination the micropyle is relatively large
(fig. 40). At pollination it is filled with the pollination droplet.
At this time the inner wall of the integument is smooth, but soon
after pollination becomes closed by the centripetal radial growth
of a portion of the inner epidermis of two sides (figs. 41, 42, 66, 67).
Closure of the micropyle in this way takes place even if the ovule
is not pollinated, my preparations showing no difference in this
respect between pollinated and unpollinated ovules. JAGER found
cases in T. baccata in which the micropyle had not yet closed at the
time of fertilization, although usually taking place soon after pol-
lination. In Juniperus both NorEéN (20) and Nicuots (19) claim
the failure of micropyle closing unless pollen of Juniperus has
entered it, foreign pollen having no effect. Experimental data
on this point would be of interest. It would seem that the pollina-
tion droplet would be a more likely growth stimulant in this region
than the presence of a pollen grain on the somewhat distant nucellus,

508 ‘BOTANICAL GAZETTE [JUNE

or of pollen tubes within the nucellar tissue. JAGER also speaks of
a ring-formed thickening at the outer end of the micropyle, a
feature not present in 7. canadensis.

' In its later development increase in thickness occurs below the
tip region, while growth in length is largely the result of chalazal
activity. In cross-section the young ovule is practically circular
in outline, but as it develops it becomes more elliptical, and, espe-*
cially in the upper portions, pronouncedly 2-ridged, the ridges
corresponding with the lips. Frequently there are three ridges,
occasionally four, the 2-lipped character, however, remaining con-
stant. STRASBURGER records finding very rare cases of 5-ridged
integuments. These ridges have been regarded as the midribs
of fused sporophylls, but, as shown later, are associated with the
vascular supply of the ovule and do not necessarily indicate a
sporophyll character of the integument.

The histology of the integument has been accurately described
for T. baccata by both STRASBURGER (35) and BERTRAND (3), @
description which will also hold for T. canadensis. Before the
hardening of the seed coat the following regions (fig. 68) are to
be recognized: (1) the outer epidermis of large papillate cells,
covered with a very heavy cuticle; (2) the hypoderm, large thick-
walled cells, which become filled with brownish-red contents and
give color to the seed coat; (3) a sub-hypodermal layer of small
radially elongated cells; (4) a thick tissue of small irregular. cells,
extending to the inner epidermis, next to which the cells are
longitudinally elongated; ‘and (5) the inner epidermis, which in
the micropyle region forms the plug tissue (fig. 67), and below, as
far as free from the nucellus, consisting of elongated thick-walled
cells containing a dark staining material. Below the union of
the nucellus and integument the boundary between the two is not
distinct. Large secretory cells are abundant in the inner tissue,
and along the 2-keeled sides the strands of vascular elements
traverse the integument. Formation of the stony character of the
seed coat begins at the apex and extends downward, involving all
_ the tissue of the integument excepting the epidermis and hypoderm,
the cells becoming “stony,” with very thick walls pierced by proto-
plasmic connections (fig. 69). The penning begins very soon

1920] DUPLER—TAXUS CANADENSIS 509

-after fertilization, and by seed maturity has reached the base of
the seed. In the meantime the aril has developed, surrounding
the hard nutlike seed.

AriL.—In the young ovule there is no indication of the aril,
but about the time of pollination the aril primordium begins to
develop as a ring at the base of the ovule (fig. 40). Its early
development is contemporaneous with the chalazal growth of the
ovule. In its early stages it is a flat saucer-shaped structure
(figs. 5, rr) of greenish color and of slow growth until the seed is
nearly matured and the seed coat hardened. Then there is very
rapid: growth; it soon becomes cup-shaped and reaches its mature
condition, that of a large red fleshy cup inclosing the hard seed
(figs. 8,43). The chalazal portion is a tissue of small cells, traversed
by the vascular elements which supply the hard integument. The
sides of the aril consist of “very large delicate-walled cells, filled
with a watery material, the long cells being extended radially and
obliquely upward. The epidermis is a narrow layer of small pig-
mented cells, and contains gm numerous stomata, oriented
longitudinally.

The morphological nature of the aril has been one of the mooted
questions in the taxads, having been regarded as: (1) a special —
outgrowth surrounding the ovule, (2) a carpel, (3) representing the
ovuliferous scale of other forms, (4) a second (outer) integument,
and (5) the fleshy layer of a single integument. RicHaRD (25)
regarded the aril as the equivalent of the collar of Ginkgo, an
accessory structure formed from the flower stalk. Briumer (4)
thought of it as a carpel, and BAILLon (2) as an expansion of the
axis surrounding the ovary. PARLATORE (22) seems to have been
the first to regard the aril as the morphological equivalent of the
ovuliferous scale of other forms, a view followed by CELAKovskyY (8)
and WorsDELL (39), both claiming the ovuliferous scale of conifers
to be the morphological equivalent of the ‘“epimatium” of the
podocarps, of the outer fleshy layer of the ovule of Torreya and
Cephalotaxus, and of the aril of Taxus. Srnnortt (33), in his study
of the podocarps, holds a similar view with reference to Cephalo-
taxus, the logic of which would be to regard the aril of Taxus in the
same light. STRASBURGER (35), with BAILLOn (2), regarded the aril

510 BOTANICAL GAZETTE [JUNE

Fic. 43.—Semi-diagrammatic longitudinal section through primary shoot with
hoot and portion of mat le, X17; outlines of primary and secondary
shoots and aril of ovule made with camera lucida, ovule inserted diagrammatically;
outlines of vascular supply also made with camera; note young ovule of next season

removed from aril, and limit of camera outline of slide from which drawing was made;
at ends of dotted lines across vascular tract indicate cross-section drawings
corresponding to these levels.

1920] DUPLER—TAXUS CANADENSIS 511

as an outgrowth of the axis, discoid in nature, a view also held of
the ovuliferous scale of other forms. BERTRAND (3) and SCHUMANN
(31) both held the aril to be a special structure, the former regarding
it as a proliferation of the cortical parenchyma at the base of the
integument (which he regarded as the equivalent of the ovuliferous
scale). JAGER (15) regards the aril as a second or outer integument,
basing his argument on the similarity in origin of the integument
and the aril.

It will thus be seen that the structure is one which has given
considerable difficulty in its interpretation, some of the explana-
tions being perhaps more ingenious than reasonable. The carpel-
lary nature of the aril no longer held sway after the acceptance of
the gymnospermy of Taxus. That the aril may be a special
structure arising from the axis and having no morphological sig-
nificance seems an unnecessary way of avoiding the problem, and
while possible is hardly probable. The view which regards it as
equivalent to the ovuliferous scale of other forms has’ more in its
favor, the chief objections to the idea for Taxus being the cauline
origin of the ovule, independent of any recognizable sporophyll,
and the belated appearance of the structure. It is hardly reason-
able for the ovule to be present for so long and to reach such an
advanced stage in development before the appearance of the struc-
ture on which it is supposed to be produced. Accepting the aril
of Taxus and the fleshy layer of Torreya and Cephalotaxus as
homologous structures, there is involved the difficulty of explaining
why the aril should be free in one form and organically attached in
the others, if representing the ovuliferous scale in all. The entire
absence of.a vascular supply in the aril of Taxus, excepting the
strands which pass through its basal portion, makes impossible an
interpretation based on its vascular features.

The question of two integuments or one seems to be partly a
matter of terminology. Distinction needs to be made between
the idea of two integuments, an inner and an outer one, and the
idea of a single integument of three layers, the outer fleshy one
of which may be more or less free from the other two. COULTER
and Lanp (10) have described the situation in Torreya taxifolia,
and speak of the outer fleshy layer of the ovule as the outer integu-
ment. Concerning Torreya, COULTER and CHAMBERLAIN (9g) state

-512 BOTANICAL GAZETTE [JUNE

that ‘‘it is a natural thing to see in these three layers character-
istics of the testa in cycads, Ginkgo, and the older gymnosperms,
and to conclude that the two integuments have arisen from a
single one by delaying the development of the region that becomes
the outer fleshy layer. These facts and the inference seem to hold
good also in the case of Taxus, the only difference being that the
outer fleshy layer (aril in this case) remains distinct from the
inner one.” In Taxus this freedom of the aril and hard integument
extends to the base (fig. 43), probably due to the fact that the
development of the aril begins relatively late. CouitTer and
Lanp’s figure of the ovule of Torreya at the mother cell stage shows
considerable growth of the fleshy layer, while a corresponding
stage (fig. 40) in Taxus shows but the beginning of the aril primor-
dium. In Torreya there is a much greater and earlier chalazal
growth of the ovule, resulting in a larger seed than in Taxus, the
bulk of which is produced below the point of juncture of the fleshy
layer and the hard coat.

In Taxus the inner fleshy layer may be represented only by the
inner epidermis, and possibly a few layers of cells in the basal
portion of the ovule, and is practically absent. The remainder
of the seed coat becomes hardened, with the exception of the
epidermis and hypoderm. It hardly seems reasonable to regard
these two layers of cells as representing the outer fleshy layer, but .
rather that their failure to develop the stony character is due to
their superficial position. “The probability is that the stony
layer would not develop superficially in any event, so that it would
not be necessary to regard a layer or two of cells overlying it (the
hard coat) as representing the outer fleshy layer (CouLTER and
CHAMBERLAIN 9, p. 418). The inference is that the outer fleshy
layer is lacking in the Pinaceae, and from the same reasoning the
outer layer of the seed coat in Taxus need not be regarded as an
outer fleshy layer. Even the claim for two integuments in the old
_ Cordaitean seeds is based on weak evidence, and the seed coat
there “may correspond to the outer fleshy layer and stony layers
of the single integument of cycads and Ginkgo”? (CouLTER and
CHAMBERLAIN 9, p. 174). Scott (32) also calls attention to the
possibility of this view. It is likely that only a single integument

t

1920] DUPLER—TAXUS CANADENSIS 513

occurs in all known gymnosperms, excepting the Gnetales. In the
older forms it is more or less distinctly differentiated into the three
layers; in the modern forms one or more layers become “reduced,”’
as the outer fleshy layers in most conifers and the inner fleshy
layer in such forms as Taxus. On the other hand, the taxads are
pronounced in the retention of the outer fleshy layer, Cephalotaxus,
Torreya, and Taxus showing an excellent series both in the delay
in appearance and in the freedom from the stony layer, Taxus
showing both these features in greatest degree.

Attempts have been made to relate the taxads to the cycads
on account of the fleshy character of the ovule, regarding Cephalo-
taxus and its relatives as bridging from cycads to conifers. The
- cycadean origin of the conifers does not harmonize with the known
facts, however, and the attempt to relate all gymnosperms with
fleshy seeds in a common phylogeny is almost as absurd as to
attempt to construct a human “family tree’? on the same basis.
The tendency to “‘fleshiness’’ is too scattered to have any phyloge-
netic significance in a broad sense, although it probably has value
within the narrower limits of small groups.

VASCULAR FEATURES

The vascular supply of the secondary shoot of T. baccata has
been described by VAN TIEGHEM (37), STRASBURGER (35, 36),
and Miss Ase (1). VAN TreEGHEM was the first to apply anatomical
criteria to the morphological nature of the ovule, and concluded
from the origin, orientation, and structure of the vascular supply *
that the ovule is a lateral structure, representing the first an
only leaf of a branch of the third order arising in the axil of the
“sixth scale’? of the secondary shoot. According to his deserip-
tion, after the fertile scale has received its vascular supply, two
bundles leave the axis, turn in such a way that the xylem is oriented
outward, and these two bundles then penetrate the ovule, where,
after forming a “‘small vascular cup,”’ they give off, ordinarily two,
sometimes three, or even four or five, branches into the integument.
He also gave the bilateral symmetry of the ovule as one of
the reasons for regarding it as axillary, bilateral symmetry
being characteristic of leaf structures as contrasted with stem

514 ‘ BOTANICAL GAZETTE [JUNE

structures. STRASBURGER (35) described the bundle supply to
the three pairs of decussate scales and to the ovule, accepting
VAN TIEGHEM’S interpretation of the situation. Later he reversed
his earlier view and regarded the ovule as terminal, there being
nothing in the course of the bundles to give a clue to the lateral
position of the ovule. He described the bundles in the integument
as consisting of long, thin-walled elements, but containing no
tracheids. Miss Aase describes the vascular supply to the ovule
and the fusion in pairs of the four bundles from the axis as different
from cases in which the united bundle is to supply an axillary
structure, the pair consisting of “‘one bundle from each side of the
bract bundle of the next lower pair, and not oné from each side
of the bract of the last pair.”” Miss Aas also pointed out the con-
centric character of the bundles in the base of the ovule, and the
possible ending of one of the bundles before reaching the ovule.
From her study the suggestion is made that there may have been
a fusion of sporophylls to form a single structure, implying “the
reduction of the ovules to one, the complete fusion of two sporo-
phylls to the integument of the ovule, and finally the reduction
of the vascular supply to each sporophyll to the single weak bundle
in the wing of the ovule.’’ She concludes, however, that ‘‘ further
investigation is necessary.’

In T. canadensis the essential facts‘are not materially different
from those of T. baccata, and a brief statemeat of the situation will
be sufficient. The secondary axis receives two large bundles from
the cylinder of the primary shoot (figs. 21, 44), these uniting at
their edges and forming a closed cylinder (fig. 45). The traces
to the first pair of scales are given off near this level (fig. 46).
Traces are then given off to the second pair of scales (fig. 47), above
which the gaps formed by the first pair of traces are closed, giving
again two large bundles in the cylinder (fig. 48). The bundles to
the third pair of scales are given off directly above those to the
first pair (fig. 40), these bundles being usually quite short, at times
not even reaching to the scale, but ending in the cortex itself. The
main cylinder now consists of four bundles, two on each side, the
pairs being separated by the gaps formed by the third pair of scale
bundles. The two bundles of each pair turn through an angle of
45° and unite laterally (fig. 51), closing the gap formed by the second 3

‘eaeet 7. 59 60
IGS. 44-60.—Figs. 44-52, series of transverse sections through young ovule
haut age aaa in fig. 11) showing normal vascular situation at various levels,
corresponding to dotted lines figured in mature ovule of fig. 43; fig. 44, two bundles
from primary shoot; fig. 4s, closed cylinder; fig. 46, bundles to first pair of scales;
fig. 47, bundles to second pair of scales; fig. 48, cylinder above second pair of scales;
fig. 49, bundles to third pair of scales; fig. 50, cylinder of four bundles in base of ovule;
fig. 51, two bundles resulting from pairing of four cylinder bundles; fig. 52, cross-
section of young ovule, showing two vascular strands in integument and cyclic
arrangement of three pairs of scales; X 2
Fics. 53-60.—Series of sections through mature secondary shoot and base of
aril showing vascular supply to 3-ridged integument and relation of xylem and phloem
in mature condition (note corresponding levels in fig. 43); fig. 53, bundles to second
pair of scales; fig. 54, to third pair of scales, one of four bundles of norma! cylinder
lacking; figs. 55-57, each of three bundles remaining distinct, becoming broader
tangentially at higher levels, and in fig. 57 showing scattered tracheids outside phloem;
fig. 58, concentric bundle with narrow zone of continuous xylem next to phloem;
fig. 59, concentric bundle consisting of small phloem strand surrounded by scattered
eids; ie 60, three phloem strands as they pass from aril to seed; X24.

516 BOTANICAL GAZETTE [JUNE

pair of scale bundles. At the base of the ovule there are then but
two bundles, with xylem and phloem in normal position, and not
showing the inverse orientation claimed for T. baccata by VAN
TrecHEM. Miss Aase’s figures of T. baccata also show normal
orientation at this level. These two bundles become more widely
separated and enter the integument at opposite sides (figs. 43, 52),
_ whence they traverse the integument almost to the tip of the ovule,
their position being indicated externally by the ridges on the integu-
ment. As Miss AasE pointed out, one of the four bundles may
terminate before reaching the base of the ovule (figs. 53-56), in
which case the odd bundle may behave in the same way as the
fused bundle. Ovules with three or four vascular bundles in the
integument occur with some frequency, such situations occurring
as a result of the failure of the fusion of one or both bundles,
in which case each bundle is continued into the integument
(figs. 53-60). Frequently when one of the four bundles of the

normal cylinder is absent (figs. 54, 55) a 3-ridged integument
"results, no fusion taking place, but each bundle remaining distinct
(figs. 53-60).

At the level of fusion the bundles are oval (fig. 51), and the
fusion bundle remains this shape for some distance into the chalaza
of the ovule. At a higher level they begin to widen laterally
(figs. 57, 58), whether fusion has taken place or not, until near the
upper level of the chalaza they reach their greatest width, both
radially and tangentially. They then suddenly become narrow,
and pass into the hard integument as narrow strands (figs. 43, 60).
The bundles are endarch throughout their course, and at the base
of the aril are collateral. Higher up, however, scattered xylem
elements, consisting of short spiral-marked tracheids with bordered
pits, appear outside the phloem (figs. 57, 58), and in the upper
portions of the aril base the bundles consist of the phloem strand
surrounded on all sides by the loosely distributed short tracheids
(fig. 59). The tracheids occur only in the aril portion of the chalaza,
the bundles as they pass into the integument consisting only of
few thin-walled elements of phloem tissue.

It would seem that the vascular supply to the ovule favors the
interpretation of it as terminal and cauline in nature. The vascular

1920] DUPLER—TAXUS CANADENSIS 517

supply arises equally from the two sides of the axis cylinder, the
entire cylinder being involved in the supply. The bundles as they
pair and fuse arise from opposite the second pair of scales and
alternate the third pair of scales, an anomalous situation if the
ovule were axillary to either of the third pair of scales. The ovule
bundle supply is a direct continuation of the axis cylinder, the
fusion of the bundles in the base of the aril closing the gap above the
second pair of scale bundles. The orientation of the bundles is
normal and presents no difficulty. The course of the bundles being
opposed to the idea of an axillary origin is also against the view
that there may have been a fusion of sporophyll with integument,
and that the integumentary bundle is a vestige of that fusion.
The presence of vascular bundles in the integument of gymnosperms
is sufficiently common to ‘cause no surprise in such forms as the
taxads, nor is there any more argument for the sporophyll nature
of the integument there than there might be in the cycads, where
sporophyll and ovular integument are not confused, unless it be
necessary to supply a theoretical sporophyll for a terminal cauline
ovule.

The terminal cauline nature of the ovule is a (Oe simpler
interpretation of the facts, according both with the ontogenetic
origin and the vascular supply. While this is an unusual situation
for a gymnosperm, it is not out of harmony with a tendency
among the seed plants, a tendency expressing itself frequently in
angiosperms and not necessarily impossible in gymnosperms.

Summary

1. The ovuliferous bud arises in the axil of a leaf early in the
season, and matures the next year.

2. The ovuliferous organ consists of the primary shoot and the
secondary shoot with the ovule.

3. The primary shoot is to be regarded as a vegetative branch
of limited growth, bearing only reproductive axes (secondary
shoots). While of limited character, at times it may become a
- functional vegetative shoot like any other vegetative branch.

4. The primary shoot is a persistent structure, functional for
several successive seasons.

518 BOTANICAL GAZETTE [JUNE

5. Occasionally the primary shoot may be terminal to a leafy
branch.

6. The secondary shoot consists of three pairs of decussate
scales and a terminal ovule.

7. The ovule arises as a direct continuation of the axis, there
being nothing in its origin to indicate that it is a lateral structure.

8. The archesporium arises from the hypoderm. ‘The sporoge-
nous tissue consists of a considerable mass of cells, out of which
one or two may function as megaspore mother cells.

9. The aril is regarded as the morphological fleshy layer of a
3-layered seed coat, delayed in appearance and physically separate
from the hard stony layer. 7

10. The ovule receives its vascular supply direct from the axis
cylinder, contrary to any axillary nature, and in harmony with
the view that it is a cauline structure.

The writer acknowledges obligations to Professors JoHN M.
CoutTer and CHarLes J. CHAMBERLAIN, under whom the study
of Taxus was begun.

Juntata COLLEGE
HUNTINGDON, Pa.

LITERATURE CITED

x. AASE, HANNAH, Vascular anatomy of the megasporophylls of conifers.
Bot. GAz. 60:277-313. figs. 196. 1915.

2. BAILLon, H., Recherches organogéniques sur la fleur femelle des Coniféres.
Ann. Sci. Nat. Bot. IV 14:186—-199. pls. 12, 13. 1860.

3- Bertranp, C. E., Etude sur la teguments seminaux des vegetaux phanero-
games gymnospermes. Ann. Sci. Nat. Bot. VI 7:57-92. pls. 9-14. 1878.

4. BLUME, , Rumphia. 3:1847 (as given by STRASBURGER 35, and
RADAIS 24).

5. Braun, A., Uber das Individuum der Pflanze. 1853.

6. Brown, R., Character and description of Kingia, a new genus of plants
found on the southwest coast of New Holland, with observations on the
structure of its unimpregnated ovule and the female flower in Cycadaceae
and Coniferae. Trans. Linn. Soc. 1825; Captain Kino’s voyage, ap-
pendix b, Bot. pp. 529-559. London. 1826.

7. CasPaRY, R., De Abietinearum floris feminei structure morphologica.
Ann. Sci. Nat. Bot. IX 14:200-209. 1860.

1920] i DUPLER—TAXUS CANADENSIS 519

8.

‘aa
Nv

=)
?

Ma
op

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taxifolia. Bor. GAz. 39:161-178. pls. I-3

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plants called Coniferae. Sg Linn. Soc. 18:163. 1839; also Ann. Sci.
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LinnaEvs, C., Genera Plantarum, 1737; 6th ed. 1764.

. Macnus, P., Zur Morphologie der Gattung Naias L. Bot. Zeit. 27: 769-

773. 1869; also, Beitrige zur Kenntniss der Gattung Naias L. Berlin.
1870.

Nicuots, C. E., A morphological study of Juniperus communis var.
depressa. Beih. Bot. Centralbl. 25: 201-241. pls., 8-17. figs. 4. 1910.

. Norén, C. O., Zur Entwickelungsgeschichte des Juniperus communis.

Upsala Universitets Arsskrift. pp. 64. pls. 4. 1907

. Oriver, F. W., The ovule of the older gymnosperms. Ann. Botany

17:451-476. pl. 24. figs. 20. 1903.

PARLATORE, F., Studi organographica sui flori e sui frutti delle Conifere.
Opuscula biitinten: 1864.

Pircer, R., Taxaceae in ENGLER’s Das Pflanzenreich. 1903.

Rapats, M. L., Anatomie comparée du fruit des Coniféres. Ann. Sci.
Nat. Bot. VII 165-968. pls. 1-15. 1804.

Ricuarp, L. C., Commentatio botanica de Coniféres et Cycadeis. Post-
humous work ediced by his son, ACHILLE RicHARD. 1826. Stuttgart.
Sacus, J., Lehrbuch. 1868.

, Lehrbuch. 2d ed. 1870

Scaacur, H., Lehrbuch der pene und Physiologie der Gewichse.
Theil IT. shes,
ScHLEIDEN, M. J., Einige Blick auf die Entwickelungsgeschichte. Wieg-
mann Beetaaht p. 289. pl. 8. 1837; also, Beitrage zur Botanik. p. 26. 1837.
signification morphologique du placentaire. Ann. Sci.
Nat. Bot. Il 12:373-376. 1839.

§20 BOTANICAL GAZETTE [JUNE

31. SCHUMANN, K., Uber die weiblichen Bluten der Coniferen. Abh. Bot.
Ver. Prov. Brandenburg 44: 1902.

32. Scott, D. H., Studies in fossil botany. 2d ed. London. 1909.

33- Stnnotr, E. W., The morphology of the reproductive structures in the
Podocarpineae. Ann. Botany 27:39-82. pls. 5-9. 1913.

34. SPERK, G., Die Lehre von der Gymnospermie in Pflanzenreich. Mem.

1879.

37. VAN TieGHEM, Px., Anatomie comparée de la fleur femelle et du fruit des
Cycadées, des Coniféres: et des Gnetacées. Ann. Sci. Nat. Bot. V 10: 269-
304. pls. I 3-16. 1869

38. WorsDELL, W. C., Observations on the vascular system of the female
“flowers” of Coniferae. Ann. Botany 13:527-548. pl. 32. 1899.

, The structure of the female “flower” in Coniferae; a historical

study. Ann. Botany 14:39-83. 1900.

39-

EXPLANATION OF PLATE XXIII

All figures were made with a camera lucida excepting figs. 2, 4, 8, 10, and
part of 43. Text figures have been reduced to one-third and plate figures to
one-half original size. The _ of magnification of the figures is shown in
connection with the description:

Fic. 61.—Archesporial initial showing hypodermal position; X475-

Fic. 62.—Two archesporial he divided, each forming primary wall cell
and primary sporogenous cell; 47

Fic. 63. file rete wall cells divided and beginning formation of mega-
sporangium wall; 475.

Fic. 64. Mar Ss cali showing several-layered wall and central mass of
sporogenous tissue (detail of fig. 39); 475.

Fic. 65.—Portion of nucellus showing several-layered epidermis (cells
without nuclei), megasporangium wall mere With nuclei), and sporogenous
tissue (shaded) with group of megaspores; X475.

1G. 66.—Portion of integument showing beginning formation of plug
tissue; M2I0.

Fic. 67.—Mature plug tissue; X 210. ‘

Fic. 68.—Detail showing integumentary regions, outer papillate epidermis
with heavy cuticle, hypoderm of large cells, sub-hypodermal layer, and
internal tissue; inner epidermis not shown; X 210. :

Fic. 69.—“Stony cells” from hard integument showing protoplasmic
connections; 210.

BOTANICAL GAZETTE, LXIX - PLATE XXIII

- _DUPLER on TAXUS

ROT OF DATE FRUIT!
J. G. BRown
(WITH FIVE FIGURES)

In the autumn of 1917, Dr. A. E. Vinson of the Arizona Experi-
ment Station brought to the writer a small box of dates from the
Yuma date orchard with the request that the organism with which
they were badly infected be determined. The fruits were care-
fully examined, but it was impossible to give the requested infor-
mation without further investigation; and it was suggested by
Professor THORNBER, Botanist of the Station, that since the
problem concerned food conservation it would be especially
profitable to attack it at once. The advice was acted upon, and
the results are partly set forth in this preliminary paper.

For the purpose of observing the disease in the field, a trip was
made to the orchard in December 1917, and a careful inspection
of trees and fruit was undertaken. A glance at the figures will
show that abundant evidence of disease was not difficult to find.
The ground under many of the trees was thickly covered with the
spoiled fruit (fig. 1), and numerous clusters still hanging to the
trees suggested a severe attack of “‘plum pockets,” for a large per-
centage of the fruit had become mummified (fig. 2). Some of the
fruit on the ground was covered with molds, and similarly infected
fruit was found wedged between the leaf bases and tree trunks
and on the ground half buried in the soil. Of the several varieties
of date palms comprising the orchard, the Deglet Noor appeared
to be the favorite host. It was stated that the year had been an
especially bad one, about go-95 per cent of the crop being infected.
The fruit was selling at the orchard at 35-45 cents per pound.
Since many of the trees produce from 200 to 400 pounds of salable
fruit under normal conditions, the loss was considerable.

Both Yuma and Tempe date orchards were affected much less
by the rot in 1918 than in 1917. Table I gives precipitation and

t Preliminary paper.

[52x [Botanical Gazette, vol. 69

[JUNE

BOTANICAL GAZETTE

avages of date rot disease; note mum-

<
d

ing ©

mies still hanging to tree and on ground.

Fic. 1.—Deglet Noor variety show

w
my
ee
ce
ey
Ss)
By
x
a)
me
)
w
9
T
>
S
&
6

Various stages of date rot and mummification

FIG. 2.

524 BOTANICAL GAZETTE | [JUNE

temperature data for the Yuma date orchard covering the two
years. Table I suggests that the greater prevalence of the fungi
concerned in the rot of the date fruit in 1917 was possibly due to
the more favorable conditions of moisture and temperature during
April, May, and June, while flowering and fruit setting were in
progress. From observations it appears probable that infection
occurs at that time. The spring and summer of 1917 had not
only an excess of moisture over the same period of 1918, but were
also cooler, so that this additional moisture was more effective.

Symptoms.—The fruits showed two main symptoms. Some
were flecked with rusty brown spots from the size of a pinhead to
areas almost covering one side of the fruit (fig. 4); others showed
soft spots varying in size and partly translucent, as though soaked
with water or oil (fig. 5). The brown spots gradually increased in
size, often coalescing, forming a dark chocolate margined area
oval in outline, with depressed, light cream or grayish centers on
which clusters of spores finally appeared in pustules (fig. 4, third
fruit, third row). The soft spots also enlarged to a similar
extent, giving an appearance of rot. In both cases the ruptured
epidermis allowed excessive water loss, resulting in the final
mummy stage. Mummified fruits sometimes remained for a time
in situ, but sooner or later fell to the ground (figs. 1 and 3).
The exposed sweet pulp, in the early stages of the soft spots,
attracted swarms of small flies and other insects which hovered
in and around the fruit clusters, and probably aided materially in
carrying the infection.

Examination of the trees revealed numerous brown spots on
petioles and ribs of leaves, which also extended down the rhachi
of fruit clusters. This suggested a relation between fruit spot and
leaf spot, which appears to be confirmed by the laboratory experi-
ments so far completed. In the Tempe date orchard palms three
years old already showed the brown spots on the leaf bases.

LABORATORY STUDIES.—Cultures have been made from the
spots on leaves, rhachi, and fruits collected in both orchards. The
medium used was date agar, prepared according to the method
described by SHEAR and Stevens? for prune agar by substituting

? Suear, C. S., and Stevens, N. E., Bur. Pl. Ind. Circ. no. 131.

-

BROWN—ROT OF DATE FRUIT

——————

he

i
ff
ae
Fume 2
viel
‘a2 4
fry
i

$

H

3.—Cluster of date fruit from left side of tree shown in fig. 1, showing most
of fruit fallen, owing to attack of spot and rot fungi

BOTANICAL GAZETTE [JUNE

526

£-o—

Le + S'v+ | £°E4 Le 6'1+ L£+4/c31+ | get | &-o4+ T*r+ | Or} [oc +* +++ yeuuon
__ way anjredaq
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£161
SainjeJadwia} aAT}e1edw0)
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Jaquiasa(y |JaquiaAoN | 1940399 |saquiazdag | ysndny | Ane aune Av | [udy | yore | <eemiqaa | Arenuef
I ATAVL

Fic. 4.—Progressive stages in mummification of date fruit, due to spot fungus;
spots conte brown at first, then dark chocolate to black, margined with lighter
depressed centers.

528 BOTANICAL GAZETTE [JUNE

dates for prunes. Infected spots in all three situations gave
typical Alternaria spores similar to those found in pustules. Be-
sides this fungus, two species of Aspergillus and one species of

Fic.

G. 5.—Stages in rotting and drying out following attack of Alternaria, Asper-
gillus, ibd Pontcdlinn: showing spots having a water-soaked appearance at firs

Penicillium usually appeared. The method of inoculation con-
sisted in the removal of a block of infected tissue with a flamed
scalpel after sterilization of the surface. The fungi appearing on
the agar have all been isolated and grown in pure culture. Onold

1920] BROW N—ROT OF DATE FRUIT 529

agar cultures numerous perithecium-like, carbonaceous structures
have appeared, which are now under histological and physiological
investigation. In no instance, thus far, have they produced spores
on artificial media, nor do they appear on infected material that
has been examined.

An important phase of the daté rot problem is the difficulty
with which stored fruits are kept. Since another investigator is
working on methods of preserving date fruit, it will suffice to
state that the same saprophytic molds that occur in infected
petioles, rhachi, and fruits on the tree are likely later to ruin the
packed crop.

ConcLusions.—From the writer’s preliminary observations and
experiments, it appears probable that the primary cause of rot
and mummification of the date fruit is the attack of Alternaria.
This attack paves the way for the entrance of saprophytic Asper-
gillus and Penicillium species which bring on the disintegration of
the pulp. Commonly all three fungi appear in cultures from the
same infected spot. Attack of the spot fungus, unaccompanied by
the saprophytic Aspergillus and Penicillium, results in mummi-
fication without the appearance of rot.

LITERATURE.—There appears to be no literature available on
diseases of the date in this country, a statement borne out by
communications from the Bureau of Plant Industry. Some
European investigators have mentioned a species of Sterigmato-
cystis as the cause of the rot of date fruit in Africa, but this fungus
has not yet appeared on any of the Arizona material examined.
Meliola has also been mentioned in connection with the spot of
the leaf of date palms, but it also is absent from cultures made in
this laboratory. Further study is needed to determine the species
of Alternaria, Aspergillus, and Penicillium isolated in cultures.
This work, together with histological investigation and inoculation
experiments, is already under way, and it is hoped that a further
report may be ready soon.

AGRICULTURAL EXPERIMENT STATION

UNIVERSITY OF ARIZONA
Tucson, ARIZ.

CUBRRENI:LILERATURE

BOOK REVIEWS

Inbreeding and outbreeding

The latest of the series of “Monographs on Experimental Biology” is by
East and Jones.t The book is noteworthy in bringing together in conven-
ient form critical data on an important subject, which have heretofore been
neither well organized nor readily accessible. Some will object to certain
conclusions, but they enhance the value of the book as a monograph, and all
assertions are supported by striking evidence.

Chapter i describes the nature of the problem, discusses its sociological,
agricultural, and evolutionary significance, and emphasizes the necessity of
proper experiments for its solution. Chapter ii outlines briefly the position
of cross-fertilization in the evolution of reproduction in plants and animals.
The conclusion is that those organisms which were able to cross with others,
at least occasionally, have dominated the organic world. For DARWwIN’s
negative proposition, ‘Nature abhors perpetual self-fertilization,” a positive
substitute is provided in, “‘Nature discovered a great advantage in an occa-
sional cross-fertilization.”

Chapter iii is a very condensed description of the réle and behavior of
chromosomes in plant and animal reproduction. Sex determination and sex
linked inheritance are also included, although the reviewer doubts whether
these are necessary. Chapter iv presents MENDEL’s law, wisely using a
1:2:1 ratio as the type illustration, linkage, and the factor hypothesis, with
particular emphasis on the inheritance of quantitative characters. The réle
of the factor as a mathematical concept, similar to the chemical atom, is ably
presented. Chapter v discusses mathematically the effect of various types of
inbreeding upon the heterozygosity of a population. Chapter vi presents

d A.
and of Darwin, G. H. SHULL, and of the. wathors themselves on plants. The
emphatic conclusion is that inbreeding is not injurious merely by reason of
the consanguinity; apparent evil results are due merely to the isolation of
certain recessives.

Chapter vii describes the experiments of Kotreuter, KnicHt, GART-
NER, NAUDIN, MENDEL, Focke, Darwin, East and Haves, RoBerts, COL-
Lins and Kempton, GERNERT, and SarGERET on hybrid vigor in plants.

* East, E. M., and Jones, D. F. , Inbreeding and outbreeding. 8vo. pp- 285.
figs. 46. Philad shia ¥ a | Lippincott Co. 1919. $2.50.

539

1920] CURRENT LITERATURE 531

The results involved increase in size (number as well as size of cells), weight,
yield, early flowering, longevity, resistance to climate and disease, seed viabil-
ity, and ease of vegetative propagation. Foreign pollen immediately produces
larger endosperm (maize) than does own pollen in different seeds of the same
ear No selective fertilization in favor of foreign pollen is associated with
hybrid vigor.s Those characters which are quickest to be modified by exter-
nal factors also show the greatest degree of hybrid vigor on crossing. On
hybrid vigor in animals, which is less noticeable, the work of Castte is
described, and that of some others briefly mentioned. Chapter viii sketches
provid

n
h ‘dominance of linked factors.’4 The faint possibility of g
“‘hybrid” vigor is discussed. Chapter ix discusses the relation of the problem
to sterility. Two distinct types of sterility occur: (1) inbreeding may isolate
sterile strains in the same way that it isolates other characters; and (2) rather
wide crosses may produce a sterile F, because through the degree of difference
between the uniting germ plasms “the precise and complex machinery govern-
ing gametogenesis cannot do its work in the normal manner, and sterility
results, although under the same conditions, developmental (somatic) cell
division goes on as usual.”
Chapter x sketches the réle of inbreeding and outbreeding in evolution.
It contains a number of interesting speculations, among which the most
striking are that hybrid vigor may be pictured as the efficient cause of the ©
establishment of the sex habit itself, and of the rise of the sporophyte genera-
j , th

r inbree
ing to isolate the combinations desired.”’ The practical utilization of hybrid
vigor is pictured also, a fairly common practice in live stock , @ rare
one in plants other than maize, for which the authors commend a double
crossing system.

The two concluding chapters present applications to the human race.
Although avowedly less exact than the earlier chapters, these are in a sense
the most interesting of all, as may appear in the following summarizing quo-
tations.

“Owing to the existence of serious recessive traits there is objection to
indiscriminate, irrational, intensive inbreeding in maf; yet inbreeding is the
surest means of establishing families which as a whole are of high value to

2 Jones, D. F., Bearing of heterosi louble fertilizati Bor. Gaz. 65:324-333-

Sigs. 3. 1918.
3 Bor. Gaz. 68:150. 1919. + 4Bor. Gaz. 66:70. 1918.

532 BOTANICAL GAZETTE [JUNE
the community. On the other hand, owing to the lex nature of the mental
traits of the highest type, the brightest examples of inherent ability have come
and will come from chance mating in the general population, the common
people so-called, because of the variability there existent. There can be no
permanent aristocracy of brains, because families, no matter how inbred, will
remain variable while in existence and will persist but a comparatively short
time as close-bred strains. But he is a trifler with little thought of his duty to
- the state or to himself, who, having ability as a personal endowment, does not
scan with care the genealogical record of the family into which he enters.”
“The hybridization of extremes is undesirable because of the improbability
of regaining the merits of the originals, yet hybridization of somewhat nearly
related races is almost prerequisite to rapid progress, for from such hybridiza-
tion comes that moderate amount of variability which presents the possibility
of the superindividual, the genius. .... Further, there must be periods of
more or less inbreeding following racial mixtures, if there is to be any high
probability of isolating desirable extremes. A third essential in the produc-
tion of racial stamina is that the ingredients in the melting pot be sound at
the beginning, for one does not improve the amalgam by putting in dross.”

One of the most valuable features of the book is the admirable bibliog-
raphy of 225 titles.—M. C. CouLTEr.

NOTES FOR STUDENTS

Temperature and the cobalt chloride method of measuring transpiration.—

In the improvement by LivincsTon and SHREVES of STAHL’s cobalt method of
measuring transpiration, one question has remained unanswered, namely, Is
it sufficiently accurate to regard the temperature of the slip as it lies on the
leaf as being the same as that of the surrounding air? SHREve‘ has answered
this question by making use of a thermo-electrical method for measuring leaf
temperatures. This method differs from previous ones in the avoidance of
the wounding of the leaf and the resulting temperature complications. Using
this method, SHREVE has demonstrated that both in the determination of the
index of transpiring power by cobalt slips, and in the standardizing of the
slips themselves over a porous evaporating surface, no error results from
using the temperature of the air surrounding the apparatus instead of the
temperature of the slips themselves.—S, V. EATon

5 Livincston, B. E., ‘The resistance offered by leaves to transpirational water
loss. Plant World 16:1-35. 1913.

Livincston, B. E., and Sureve, E. B., Improvements in the method for deter-
mining the transpiring power of plant suriates by hygrometric paper. Plant World
19: 287-309. 1916

° SurevE, E. B., A thermo-electrical method for the determination of leaf tem-
perature. Plant World 22:100-104. figs. 2. 1919.

———., The réle of temperature in the determination of transpiring power of
_ leaves by hygrometric paper. Plant World 22:172-180. Sig. I. 1919.

1920] CURRENT LITERATURE 533

Anatomy of strand plants.—The eastern shore of Madagascar, charac-
terized by uniformly high temperature, constant winds, and considerable rain-
fall, has as its principal strand communities two associations characterized
respectively by Ipomea Pes-caprae and Barringtonia. The plants of the
ormer have been examined by DENnts,’ who finds them, thus exposed to con-
ditions of high transpiration, induced by great insolation and rapid air move-
ment, almost without any special development of epidermal protection, but
possessing varying degrees of fleshiness with water-storing tissue rather well
developed. One group shows isolateral fleshy structure with the water tissue
centrally placed, another possesses bifacial leaves, less fleshiness, and periph-
eral water tissue. These structural tendencies toward fleshiness are related
by the author to the saline character of the beach; the development of water-
storing tissue and the early lignification of the roots to the high rate of trans-
Piration; and the abundance of palisade tissue to brilliancy of both the direct
and the reflected sunlight. The details of structure are given in the text and
in the drawings of leaf sections —Gro. D. FULLER.

Snow and timber line.—From studies made in the Pyrenees, BoucEt®
has reached conclusions regarding the influence of snow upon alpine and sub-
alpine vegetation not unlike those of SHAw? from a study of the Selkirks
more than a decade ago. In the higher altitudes the duration of the snow is
related to the local topographic relief, and its persistence during the growing
season profoundly influences the character of the vegetation. In depressions
it collects during the winter and remaining late in the season gives rise to a
rather mesophytic herbaceous community consisting of a mixture of lowland
and alpine forms. In contrast, the relative absence of snow upon the ridges and
at the same altitude produces a xerophytic vegetation in which trees and woody
plants are conspicuous. Thus the upper limit of trees or timber line is much
higher upon ridges than along depressions.—Gro, D. FULLER.

Action of enzymes on cellulose.—PRINGSHEIM and MAGNUS-VON
MERKATz® point out that dextrines from both starch and glycogen are split
to maltose by diastase. They raise the question whether diastase has a
similar effect on cellulose dextrine. By using MADSEN’s acetylization method
they gained cellulose dextrine from cotton that was soluble in water and

7 Denis, Marcet, Recherches anatomiques sur quelques plantes littorales de
Madagascar. Rev. Gén, Botanique 31:33-52, 115-120, 129-142. pl. 1. figs. 12. 1919.

8 Boucet, J., De l’influence des neiges sur la répartition des différents végétaux
a méne altitude dans les Zones élevées des Pyrénées. Rev. Gen, Bot. 30:305-320.
1918, :

9 SHaw, C. H., The causes of timber line on mountains; the réle of snow. Plant
World 12: seoibh. Jigs. 4. 1909.

GSHEIM, H., and MaGNus-von unin , A., Fermentversuche an Zel-

lulose abbauprodukten. Hoppe-Seyler Zeit. Physiol. ‘Chen! 10§:173-178. 1919.

534 BOTANICAL GAZETTE [JUNE

gave no osazone reaction. The dextrine thus obtained is strongly reducing

to Fehling’s solution, and is considered by the authors as the end dextrine of

llulose. Diastase will not split cellulose dextrine. They also derived
od

cattle, the intestine, and the pancreas bore no enzyme that would split zello-
iose. They conclude that the splitting of this substance in the alimentary
canal of the cattle must be due to cellulose bacteria——Wa. CROCKER

Ecological diversity and generic coefficients.—The principle first enunci-
ated by JaccarpD, and noted in this journal,” that the ratio between species
and genera, or the generic coefficients, varies inversely with the diversity of

UFRE
santas Diversity of ecological conditions was found at altitudes of 1100 m.
to 2000 m. in the valley of Baréges, where the generic coefficient for rusts was
20 per cent and for all fungi 40 per cent. Contrasted with this were the
uniform conditions in a wheat field showing generic coefficients for its fungi of
70 per cent, and upon sand dunes with coefficients ranging from go to 100 per
cent.—Gro. D. Futter.

Lignins.—PRINGSHEIM and MAGNUS,” in a study of lignins, have obtained
some interesting results. When wood or straw is treated with sodium hydrate
in the cold, all the acetic acid liberated is derived from the lignins of these
materials. When these materials are boiled with sodium hydrate, either

under pressure or otherwise, most of the acetic acid formed is derived from
the lignins; but a small part is derived from the cellulose and none from the
pentoses. The lignin of the white beech yields about 37.85 per cent of its
weight of acetic acid, and the lignin of conifer wood about 19.48 per cent.
—Wa. CROCKER

Dioecism in Thalictrum.—SCHAFFNER™ has studied Thalictrum dasycar pum
in reference to intergrades between the monoecious and dioecious condition.
It seems to be a peculiarly favorable form for this purpose, and almost every
conceivable intermediate in the expression of “maleness’” and ‘“femaleness’’
wasfound. The author rightly calls attention to the fact that the physiological
and ecological factors concerned in these various expressions must be taken
into consideration for an understanding of the evolutionary Sogo! leading
from the bisporangiate to the monosporangiate condition.—J. M

* Bot. GAz. §7:540. 1914.
"= DUFRENOY, J., nO — et coefficients génériques. Bull. Trim. Soc.
me ate Fr. 35:27-46. 19
HEIM, H. rae M acnvs, H., anh den Acetylgehalt des Lois, Hoppe-
ee Bae 3 Physiol Chem. 105:179-186. 19
4 SCHAFFNER, J. H., Dioeciousness in tatiodi dasycarpum. Ohio Jour. Sci.
20:25-34. I9I9.

1920] CURRENT LITERATURE 535

Fungi of North Carolina—CoKeEr® has published a systematic account
of certain genera of fungi occurring in North Carolina, illustrated by remark-
ably fine plates. Craterellus is represented by 7 species and Cantharellus by 12.
Eomycenella, Tragia, and Nyctalis are each represented by a single species.
very complete key to the genera of gill fungi (55 genera) is also included.
—J.M

New genus of Pyrenomycetes.—Fitzpatrick™ has described a new genus
(Rostronitschkia) of Pyrenomycetes from Porto Rico and Jamaica, parasitic

the leaves of Gesneria albiflora. The species has been known for some
time, and described by ReEum (in litt.) as a new species of Nitschkia
(N. nervinicola). Fitzpatrick has concluded that it is distinct enough from
that genus to be entitled to separate generic rank.—J. M. C.

Mutation.—Costantin” has published a full discussion of the states
of the theory of mutation, weighing the evidence for and against it, as presented
in the extensive literature of the subject. His conclusion is that, in spite of
the violent assaults against it, “la theorie de la mutation reste debout.”
The details of the discussion will be well worth consulting by those interested
in this controversy.—J. M. C.

Suspensor of Capsella.—SovEcEs® has made a remarkably detailed study
of the early embryogeny of Casella, especially in reference to the suspensor.
The numerous details cannot be repeated in a brief review, but they should
become familar to morphologists. That so much could be obtained from a
form so commonly studied is remarkable.—J. M. C.

Tropical American Eupatoriums.—RosInson,” in continuing his studies
on the South American species of Eupatorium, has paid particular attention
to those of Peru and Bolivia. In the present contribution 37 new species
are described, and a review of the Peruvian material recognizes 82 species.

1, ME: .

%3 CoKER, W. C., Craterellus, Canthareilus, and related genera in North Carolina;
with key to the genera of gill fungi. Jour. Elisha Mitchell Sci. Soc. 35:24-48.
bls. 17. 1919.

6 Frrzpatrick, H. M., Rostronitschkia, a new genus of Pyrenomycetes. Mycologia
11:163-167. pl. 17. 191

1 CosTANTIN, J., La mutation, état actuel de la question. Ann. Sci. Nat. Botan-
ique X r:iii~xxxli. tg19.

8 Sources, R., Les premiéres divisions de l’oeuf et les différenciations du suspen-
seur chez le Capsella Bursa-pastoris Moench. Ann. Sci. Nat. Botanique X 1:1-28.
Jigs. 69. 1919.

% Ropinson, B. L., I. On tiokcel: American Compositae, chiefly Eupatorieae.
II. A recension of the Eupatoriums of Peru. Proc. Amer. Acad. 55:1-88. I919.

536 BOTANICAL GAZETTE [JUNE

Fumaria a Rupicapnos.—Pucs.LEy” has published a very detailed
revision of Fumaria and also of Rupicapnos whose species were formerly
included in Fumaria. In Fumaria 46 species are recognized, 6 of which are
new; in Rupicapnos 20 species are recognized, 7 of which are new.—J. M. C.

New genus of Rubiaceae.—REHDER™ has described a new genus (Tetra-
plasia) of Rubiaceae from the Liukiu Islands, an evergreen shrub endemic to
the islands. It is thought to belong to the Vanguerieae, and is most closely
related to Plectronia and Vangueria.—J. M. C.

New conifers.—WI1son” has discussed four new Korean conifers, one, a
Thuja, having been described in 1919 by Nakai. The others described by
‘WILSON are a new species and a new form of Abies, and a new form of Larix.

ls Me

2 PucsLey, H. W., A revision of Fumaria and Rupicapnos. Jour. Linn, Soc.
Bot. 44:233-355. pls. 9-16. 1919.

* REHDER, ALFRED, Tetraplasia, a new genus of Rubiaceae. _ Jour. Arnold
Arboretum 1:190-191. 1920.

727 Witson, E. H., Four new conifers from Korea. Jour. Arnold Arboretum
1:186-190. 1920.

GENERAL INDEX

Classified entries will be found under Contributors and Reviewers. New

names

and names of new genera, species, and varieties are printed in bold face type; syno-

nyms in italic.

Abeliophyllum
\bietineae, polyembryony among 153
\frican plants 360
\leurone oar inheritance in maize 407
pine vegetation of Central Andes 354
\lway, F. J., work of 352
oromorpha 18, ete
hiatoees of prairie
indes, alpine enctaeine _ oun 354
\ntarctic

270; island Se prs 95
Aposporella 11, elegan
Apple bark, oxidase activity of 218

na 20

aaa [ote en Se ahr 2
=

ret, 4 of 95

etteitteieatn
Auerswaldia Cociopbie 248

~ 2
Bakke, A. L., eat * Ang
B , Phi

am
Paey, effet of st high @ and low tempera-
Bellamy, ~ W., work of 357

¥. work of 354
Biological fluids, wea Sai of 269
En G. R. 193
Blasia, s permatogenesis in 258
Blix, R., work of 356
ore J at of 533
— ., ‘Joseph Dalton Hooker”

Rove G., work of 188
Braun- oar J., work of 184
Brown, J. G

rown, W. a men of 445, 448

Buchholz, 4, ete
Bulbils of Lycopodium lucidulum 426

C
Cacti, carbohydrate economy of 91
ppernaigg W. A., work of 353

=.

vegetation

Cantharosphaeria chilensis 3
Capsella, Miri’ of 535

Carbohydrate economy of cacti 91
Carbon Vtoxide, effects on roots 3
, ‘Tidal lands” 350

Catacauma, ‘Ocoteae 251; palmicola 251;
urbanianum 252

Catacaumella Gouaniae

Catalase activity in vent cells 356

Cellulose, ee of enzymes on 533

Chamberlain, . 192

Chaney, R. W., Hepa of 192

Cheeseman, T. F

.. work of 95
Child, C. M. work a 187, 188, 357
vumber i n Sequoia, 348

r, W. e work of 535

Colotada grasslan ds’ 358; sedge asso-
ciations in in 360

Compositae, origin and development of

Conifers, new
Contributors: hes, Agnes 337, 438;
Arthur, J. M. 271; by, G. R. 193;
Brown, J. 521; Buchholz, J. T.
153; Chamberlain, C. J. 192; Clay-
berg, H. D. 28; Coulter, J. M. 96,
359, 360, » 448, 535,_ 5393
Coulter, M. C. 407, 530; Cowles, H. C.
350, 356; Crane, M. P. 3 rocker,
- 94, 96, 356, 357, 358, 533, 5345
orsey, M. J. 301; ff, G. H. 341
Dupler, A. W. 492; Eaton, S. V. 269,

272, 357, 532; Fuller, G. D. 92
183, 185, 192, 270, 272, 351, 354, 358)
359, 360, ae: 448, 533, 534; Good-

upt, A. W. 318;

Langdon, LaDem: :
Hy 9F ; Noyes, H. A. 332; Over-
holser, E. L. 273; Phillips, T. G. 168;
, 18; Rose, . 218;
a: . W. 88,

Schertz, rtz, F. M. 733 harp,
258; Shull, Cs. A. 287, 361; Smith,
R. W. 426; Snow, Laetitia M. 297;

$37

538

Stevens, F. L. 248; — Aravilla
; Thaxte

scute sae st edie’ 179
Correlations

5
- 96, 359, 360, 444, 448, 534,
535) 5

couee M1 C. 407, 530

dates H.C. 350, 3 56; work of 184
Crane, M. P. 348

Crocker, W. 94, 9°, 356, 357, 358, 533, 534
Crop centers 56

Cytology of gigantism 192

D
ae: on” rot of 521
., Wor 533
Diant gms of water plants
Dicotyledonous us woods, pre structure

Digby, L , work of 88

269
Portoricensis 249

Dufren renoy, J. work of 350, 534
Duggar, M., work of 269
Dupler, hi
Du Rietz, C. Ek. ee of 184

E
are “Inbreeding and out-
Eaton, S. ah 289, 272, 357, 5

Ecol ossil plants seca? * statistical
83" ap 185; terms and concepts of

E. “oat

bf ”

Beological diversity and generic coeffi-
ts 534
pets of Verbena 64

=]
Be

American 535
of water by leaves 358

INDEX TO VOLUME LXIX

[JUNE

F

Farlow, be ages boipr — of 83
Farmer, i of 9
Fermentation Babs

Fertilization of Verbena 61

oO
ork o

Flood, restiry, G, work of Phe BS

Flowering gona and a

Folsa of 2

ossombronia cristula, life history of 318
rk of 90

Fraser, H. C. I., wo

Fries, T. ee f a

Fruitfulness and ao eas 259

Fuller, G. D. 92, 183, 185, 192, 270,
272, = 354, "358, 359), 300, 445, 447,
448, 533, 534; work of 185

a

Fungi, biology ack culture of 188;
ecology of 359; North Carolina
535; tyrosin in x

Fun, ungus-parasites of insects 1

Gams, H., work of 184
Geoglos ossaceae, devon of 34
and Soohinieal diver-

Goce coefficients
sity 5 -
Geotr esponse, chemical and physi-

cal c anges durihg 168
96

rmination
igantism, c ileay of 192
pe E. “Syllabus der Pflanzenfamilien”
Glonzella rubra 254
Goodspeed, i 348; work of 448
Grass embr

Nectandrae

of go
Guignardia, —— 2553
255; Tetrazygiae 255

Hall, H. M., work of 448
Halstedia i

A. w
Hayden, Ada, work of 272
Hooker, Joseph Dalton 444
I .
ae of 359
Inbreeding and Nig dtesar g 53°
Insects, fungus-parasites of

a

1920]

Johnson, D. S
Johnson, J., work of 9
Jones, P., “Inbreeding and out-
breeding” 530; work of 5
Jones, H. A. 127
Jérgensen, W., work of 191
K
Kanda,

M. 54
Kidd, is a of 190
Kneiffia
Kraybill, HL. R. 218
eagt ©
lg dg 17; Termitarius 17
va, effects of carbon dioxide

Lanta LaDema M. 189, 2
patti graces of water ae 358

Lignin:
Tiliecelae a ars tse In 337

Linsbauer, “‘Handworterbuch der
Botanik”
Livingston, B. E., work of 532

Lloyd, F. C, work o acho
Lutman, B. F., work o:
Enchaadiins susan: ‘bulbils of 426

M

McLean, R. C., work = 3), 445
Mahoganies, identifica
Maize, inheri e of pipe color in
407; pao ang ee coleoptile
aple seeds, er, nid. of 127
_ arkle, M. §. ork of 3

Mosier, plant 96
Muiaria, curvata 10; fasciculata 11
e9

Muiogone Medusa
Mutation 535

N
Nakai, T., work of 96

Noé, A
me Carolina, Sung of 535
332

- Noyes, H. A.

Oliver, F. W., “Tidal lands” 350
Ophio, ‘oglossaceae, p — membrane
in 237

INDEX TO VOLUME LXIX

539

Osmotic agar in skye 272
Osmunda, mitosis in 88

Overholser, E. L. 2 :
Ovuliferou ivictaee Sof Taxus canadensis

Oxkinse activity of apple bark and salts
218
i xe

Parasitism 357
avillard, J., de se 183, 184
of 2

Petiolar glands in plum

Petoskey-Wa a8 abe cals upland
societies 0

Phacoiothopels — 252

Phillips, T. G. 1

Phyllodes in ‘itates 337

Phyllosticta bonduc 2 se

Physalospora Hoyae

Pi aeons mete a ia T Ocbdaalcemicese

237
ine, petiolar glands in
Polyembryony among Abltineae 153

i
9)
ar
ws
wn
os

H. ork of
’yrenomycetes, aw genus of 535 ©
R
Ramaley, F., pon of 358, 360

tk of 96
” Bower's * Jose Dalto
r 444) Carey’s "Rida lands”

“Origin | and hae geen 0
Willis’ “Dictionary of
444

3
e on 332;
351

540

Rose, D. H. 218

Rose, R. C. 218

Rot of date fruit 521
Rubber, a new

Ru biaceae, new genus of 536
Rupicapnos 53 At

Russell, G. A., work of 96
Rydberg, Pr oe cae of 360

S

of 448

Botanik”® 4
— Spot pagar study of 127; temper-
and rate of moisture intake 361
, chromosome number in 348
Chants HL Ix a of 352
Sharp, L. W. 88, 258; work of 90
Shaw, a. Be aoe of ae

Stiles, \ Ww. , work of 190, IQ

Strood plants, anatomy of 533
seed, chemical analysis of 72
of Capsella 535
Svanberg, O., work of 358
=
Taylor, Aravilla M.
Taylor, R. H. 273 ey
pig canadensis, ovuliferous structures
0

‘gece effect on barley 9
Tendrils of Smilax 438 bes

INDEX TO VOLUME LXIX

rk
., “‘Handwéorterbuch der.

[JUNE 1920

Thaxteriola 14; nigromarginata 15
Thellung, A., work of 360

ranspie iration in tropical rain forests 92;
method of measuring i studies 447
Trees of Pennsylvania

nee rain iaeits es transpiration

Turrill, W. B., work of 270
Tyrosin in fungi 191

U

Uleodothis Pteridis 248
Umbelliferae, new genus of 360
Uromyces, abbreviatus 204; amoenus
210; bauhiniicola 201; Bidentis 212;
erod :
hyalinus 213; oc meaaipion 203; mon-
tana 214; M es 208; nevadensis
207; Pavoniae ae Rudbeckiae 215;
short cycle 193; Solidaginis 209
Tranzschelii 206

Verbena, field and laboratory studies of
54

et ater see diaphragms of 297
NESS 259

amanouchi, S., work £ 90
fay cells, catalase a betivity in 356

Z
Zignoella algaphila 256