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THE
BOTANICAL GAZETTE
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS
Bgents
THE CAMBRIDGE UNIVERSITY PRESS
» LONDON AND EDINBURGH
THE MARUZEN-KABUSHIKI-KAISHA
TOKYO, OSAKA, KYOTO, FUKUOKA,
THE MISSION BOOK COMPANY
SHANGHAI
THE
BOTANICAL
GAZETTE
EDITOR
JOHN MERLE COULTER
VOLUME LXIII
JANUARY-JUNE 1917
WITH
JTY-FIVE PLATES AND ONE HUNDRED AND FOUR FIGURES
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS
">
1^
Published
January, February, March, April, May, June, 191 7
Composed and Printed By
The University of Chicago Press
Chicago, Illinois. U.S.A.
TABLE OF CONTENTS
Oenothera Lamarckiana mut. velutina (with plate I) Hugo DeVries
Influence of the leaf upon root formation and
geotropic curvature in the stem of Bryophyllum
calycinum and the possibility of a hormone
theory of these processes (with thirty figures) Jacques Loeb
Prothallia and sporelings of three New Zealand
species of Lycopodium. Contributions from
the Hull Botanical Laboratory 222 (with
plates II and III) ------ Charles 7. Chamberlain
Prothallia of Lycopodium in America. Contribu-
tions from the Hull Botanical Laboratory 223
(with twenty-one figures) ----- Earle A . Spessard
Similarity in the effects of potassium cyanide and
of ether (with one figure) -
A comparative study of winter and summer leaves
of various herbs. Contributions from the Hull
W. J- V. Osterhout
Botanical Laboratory 224
7. P. Stober
Imperfection of pollen and mutability in the genus
Rosa (with plates IV- VI) -
Morphology of Keteleeria Fortunei. Contributions
from the Hull Botanical Laboratory 225 (with
plates VII and VIII and three figures)
The pollination of Vallisneria spiralis (with plate
IX and six figures)
Tolerance of fresh water by marine plants and its
relation to adaptation ------
Temperature and life duration of seeds. Contribu-
tions from the Hull Botanical Laboratory 226
(with five figures)
A report on some allocthonous peat deposits of
Florida. Part II: Morphological (with plates
X and XI)
The response of plants to illuminating gas. Con-
tributions from the Hull Botanical Laboratory
227 (with six figures)
PAGE
I
25
51
66
77
89
Ruth D. Cole no
A. H. Hutchinson 124
Robert B. Wylie 135
W. J. V. Osterhout 146
James F. Groves 169
Carl C. Forsaitk 190
Sarah L. Doubt 209
VI
CONTENTS
[volume lxiii
PAGE
The supposed action of potassium permanganate
with plant peroxidases - H. H. Bunzell and Heinrich Hasselbring
Leaf nectaries of Gossypium (with plates XII and
XIII and one figure) ------ E. L. Reed
The reaction of plant protoplasm - A. R. Haas
Environmental influences on nectar secretion.
Contributions from the Hull Botanical Labora-
tory 228 - - Leslie A. Kenoyer
Development of embryo sac and embryo in
Euphorbia Preslii and E. splendens (with
plates XIV-XVI) ------- Wanda Weniger
The development of the ascocarp of Rhizina
undulata Fr. (with plates XVII and XVIII) - Harry M. Fitzpatrick
Problems of plant pathology ------ F. L. Stevens
Flowers and insects. XX. Evolution of ento-
• mophilous flowers ------- Charles Robertson
Does the temperature coefficient of permeability
indicate that it is chemical in nature ? - - W.J. V. Osterhont
A study in physiographic ecology in Northern
Florida. Contributions from the Hull Botani-
cal Laboratory 229 (with ten figures) - - Laura Gano
Permeability of certain plant membranes to water.
Contributions from the Hull Botanical Labora-
tory 230 (with two figures) ----- F. £. Denny
Arbores fruticesque Chinenses novi. I - Camillo Schneider
Peculiar effects of barium, strontium, and cerium on
Spirogyra (with two figures) ----- 5. 5. Chien
Development of Dumontiafiliformis. II. Develop-
ment of sexual plants and general discussion of
results (with plates XIX-XXII and seven
figures) ---------- Grace A . Dunn
Permeability of membranes as related to their com-
position. Contributions from the Hull Botani-
cal Laboratory 231 (with six figures) - - F. E. Denny
Sexuality of filament of Spirogyra (with plates
XXIII-XXV) -------- Bert Cunningham
Orange rusts of Rubus (with one figure) - - - /. C. Arthur
Arbores fruticesque Chinenses novi. II - Camillo Schneider
225
229
232
249
266
282
297
307
317
337
373
398
406
425
468
486
=;oi
516
VOLUME LXIIl]
CONTENTS
vil
Briefer Articles
Henry Harold Welch Pearson (with portrait) Charles J. Chamberlain
Soil moisture index
PAGE
A freezing device for the rotary microtome (with
one figure)
A method for ' producing conductivity water suit-
able for water culture experiments (with one
figure) ----------
Manipulating microscopic organisms in staining -
The Botanical Station at Cinchona -
IsO
Francis Ramaley 151
N. L. Gardner 236
R. B. Harvey 321
/. Ben Hill 410
D. S. Johnson 412
Current Literature 81,153, 240, 323, 414, 524
For titles of book reviews see index under
author's name and reviews
Papers noticed in "Notes for Students" are
indexed under author's name and subjects
DATES OF PUBLICATION
*
No. i, January 15; No. 2, February 15; No. 3, March 15; No. 4, April 16;
No. 5, May 16; No. 6, June 19.
ERRATA
Vol. LXIII
P. 50, line 17 from top, for fig. 15 read fig. 14
P. 50, line 18 from top, for fig. 16 read fig. 15; also insert fig. 16 after leaf
P. 80, last line, for have connection read have no connection
P. 142, legend of fig. 4, for verticle read vertical
P. 272, line 16 from top, for fig. 15 read fig. 18
P. 277, line 2 from bottom, for 5 read 6, and insert between 4 and 6 the fol-
lowing: 5. The nucellus forms a beaklike prolongation, which disintegrates
after the embryo is formed.
aiLLl Lilt ^lllULJKJ 13 1^1111V,*J.
P. 279, line 14 from top, for 5 read 3
\
VOLUME LXIII
NUMBER I
THE
Botanical
Gazette
JANUARY ran
OENOTHERA LAMARCKIANA MUT. VELUTINA
Hugo DeVries
(with plate i)
One of the rarest mutations of Oenothera Lamarckiana is that
changed
hybrids
more
striking because in hybrid combinations these twins ap
and, as it seems, easily. But in the same way many o
tions, which apparently might reasonably be expected
muta
must
may
very rare. Why some mutations are common and others r;
still an open question.
From the behavior of the twin hybrids in crosses we
deduce that the mutant velutina must be in the main recessive to
the parent species, and that the mutant laeta should be dominant
over the velutina. If there were but one character involved, this
would mean that the mutant laeta must be externally like O. La-
marckiana, and the same conclusion would have to be admitted
if there were more characters indissolubly bound together. This
being granted, the laeta could, of course, never be expected to
appear as a mutant.
For some years, however, my cultures tend to show that the
mutations observed in the group of the Oenotheras are far more
compound phenomena than I was formerly inclined to assume.
This also seems to be the case with the splittings which so often
1 De Vries, Hugo, On twin hybrids. Bot. Gaz. 44:401-407. 1907.
2 BOTANICAL GAZETTE [january
occur after hybridization, and especially with those which appear
in the first hybrid generation. If we apply this view to the twin
hybrids laeta and velutina, the possibility is at once revealed that
the components of this group of characters might not always be
so indissolubly connected, and that some deviating combination
of these qualities might still produce a mutant laeta, different from
the type of Lamarckiana. As a matter of fact, a pure and com-
plete mutant velutina has appeared in my cultures, but a laeta
has never been seen as a mutant. In crossing this velutina with
the parent species, however, twin hybrids arose, one of which may
be designated as laeta, as will be shown later.
The question whether the characters of mutants and of hybrids
among the Oenotheras are single or built up of a less or greater
number of theoretically independent units now seems to be one of
principal interest to me. Until now, however, the analysis of
the qualities of the twin hybrids laeta and velutina has been diffi-
cult and unreliable on account of the presence of the hereditary
qualities of their other parent. We can make inferences from these
by comparing the twins issued from the crosses of different species
with O. Lamarckiana, but we can hardly expect to get a complete
analysis in this way. The mutant velutina is free from these
specific admixtures, and therefore may afford a better material for
experiments in this direction. I intend to study it from this point
of view by means of a number of crosses, most of which I made
during the summer of 191 5, and shall give here only a description
of the mutant itself, and of those hybridizations which give proof
of its right to the name of velutina.
In order to avoid the confusion which might easily arise from
the similarity of the names O. Lamar ckiana hyb. velutina and O.
Lamar ckiana mut. velutina, I will give a synonym to the latter and
call it 0. Lamarckiana mut. blandina, or briefly 0. blandina. In
descriptions the use of this latter term will be obviously the easier.
O. blandina has throughout its life and in all its organs a paler tinge
than O. Lamarckiana.
O. blandina is, in all respects and at every stage of its evolution,
strikingly different from O. Lamarckiana and easily recognizable.
Its marks become visible with its very first leaves, when still in the
1917] DeVRIES— OENOTHERA 3
about
At the time when the
seedlings must be planted in larger boxes, their marks are fully
reliable, even in hybrid mixtures. Their leaves are narrow and
a pale yellowish green, whereas those of 0. Lamarckiana are broad
and a deeper green. As the rosettes increase the number and the
typ
some weeks more
are ripe for transplanting into the garden, O. blandina is clearly
a type of its own and can easily be counted off in the mixtures.
In May the rosettes of O. Lamarckiana gradually become very stout,
but those of 0. blandina remain slender. The leaves are so narrow
as not to touch each other regularly nor to cover the ground
between them. They resemble those of O. rubrinervis, but lack
the brittleness, the typical bending of the petiole and blade, and the
specific color of this form. Moreover, they show a high degree of
fluctuating variability in their color. This is always gray, on
account of the hairiness of the surface, but it varies between a
normal green and a more or less pale and yellowish tinge. The
paler they are, the poorer they are in chlorophyll, and therefore
the palest individuals soon begin to show a slower growth. They
stay behind the others the more, the paler they are. These differ-
ences increase if the culture is densely planted, and even at the time
of flowering the paler individuals may be seen to be much weaker
and shorter than the others. In ordinary cultures, however, when
the plants are at a distance of 20 cm. or more from their next
neighbors, and grown in a well manured soil, these differences
gradually disappear and are no longer visible when the first flowers
open. In order to fertilize pale individuals beside the green ones,
I had to mark them in early youth. From the self -fertilized seeds
of the green ones the seedlings are on the average less pale than
those of the paler parents, but the difference, although obvious and
unmistakable on the beds in springtime, soon disappears as the
summer begins. From time to time there is even a partial vari-
ability, such as, for instance, a green branch on a stem with pale
leaves. This shows that there is no racial difference between the
green individuals and the pale ones, even as in the cases of Oeno-
thera (Lamar ckianaXatrovir ens) gracilis and of O. (Lamar ckianaX
4 BOTANICAL GAZETTE [january
Hookeri) velutina. 2 Since making these experiments (1912-1913)
I have cultivated O. blandina so as to reduce the paleness of its
leaves to the first youth of the rosettes, and to have no diminution of
the individual strength of my seed-bearing specimens on account of it.
At the time of flowering the plants are much more slender than
those of O. Lamarckiana, and are in their main features very much
like the velutina hybrids of 0. biennisX Lamar xkiana and of 0.
Lamar ckianaXO. biennis Chicago, and especially like the latter,
with which in some instances they can easily be confounded. The
leaves on the stem are narrow, reaching about two-thirds the
breadth of those of Lamar xkiana if compared by equal length. In
the beginning they are folded along their midvein, but later they
become flattened, and this curious character may then be seen
only in the bracts of the inflorescence. The bubbles, which are so
characteristic of the leaf blades of O. Lamar xkiana, are absent in
the mutant. I shall designate this lack of bubbles by the term
"smooth."
The flowers of O. blandina are cup-shaped, whereas those of the
or less quadrangular. The size is the same,
more
bright, and the stamens show no marked
pollen is very large in both cases. Th<
gma
widely spread out above the anthers, the distance being even some-
what larger in the mutant (1 cm. against 0.5cm.). The flower
buds are almost twice as thick in the mutant, more regularly and
more deeply colored with red brown lines and spots, and much
more hairy. This color and this hairiness extend over the tube of
the flower and the ovary, and in a less degree over the top of the
stem and
mng bracts. The small free tips at
thick in O. blandina but thin in O
The differences of the fruits are small, except for the hairiness.
The most striking character of O. blandina, however, is seen at the
end of the flowering period, when the spikes are long and the lower
fruits begin to ripen. At that period the spikes are very slender,
with few fruits and long internodes, whereas on the spike of O.
Lamar xkiana the fruits are densely crowded. I counted the fruits
3 Gruppenweise Artbildung. Berlin, 19 13, p. 164, where O. atrovirens still bears
the name of O. cruciata {fig. 73) ; and p. 116, fig. 46. for the twin hybrids of O. Hookeri.
19 1 7] DeVRIES— OENOTHERA 5
on a length of half a meter in the middle part of the spike, at the end
of September, and found 30 of them on 0. blandina, but 75 on O.
Lamarckiana, both on very vigorous annual specimens. From
this the internodes of the spike are 1 . 7 against o . 7 cm., or more than
twice as long as those of the parent species. The average numbers
of flowers which open on a spike during an evening are inversely
proportional to these figures. For many crosses I have castrated
five successive flower buds of 0. Lamarckiana on one day and
pollinated them the next day, whereas the crossing of 5 flowers on
a spike of O. blandina usually lasts 4 or more days, which makes
quite a difference in the technical work.
Of course, there are a number of distinguishing points of less
value, but their description would remain vague unless strict
averages could be given; and since all characters are more or less
dependent upon the conditions of soil and culture, it is doubtful
whether even averages would be reliable. I shall return to this
point in the description of the hybrids.
In comparing this description with that given in my book on
Gruppenweise Artbildung for O. (Lamar ckianaXO. biennis Chicago)
velutina, it will easily be seen that the two belong to the same type.
In the garden, when groups of 10-30 plants are compared, this
similarity is of course far more striking. It is at once clear that
O. blandina must be a true and pure velutina.
If we now try to resume this description in such terms as to
distinguish a number of probable units, the combination of which
might constitute the type of velutina, I might propose the following:
(1) slender stature; (2) long internodes of the flower spike; (3)
leaves narrow, folded longitudinally and smooth, that is, without
bubbles; (4) flowers cup-shaped; (5) hairiness of all organs;
(6) abundance of red color in the younger parts. It is obvious,
however, that some of these points may go together and depend
upon one unit, but on the other hand it must be conceded that this
list may be far from complete. Most of these assumed units are
recessive to the corresponding qualities of O. Lamarckiana, but
the smoothness is dominant over the bubbles, which are evidently
due to a lack of growth parallel to the surface of the blade of the
leaf. This enables us to separate smoothness from the larger part
6 BOTANICAL GAZETTE [jaxuary
means
dealing with the hybrids.
I shall now describe the origin of O. blandina and the pedigree
of the race derived from it. As a matter of fact, this mutant did
not arise directly from O. Lamarckiana, but through another
mutant race as an intermediate. This was the fertile race of
0. lata issued from an original fecundation of my normal 0. lata by
means
Grupp
is race is described in my
256, 257. In the fourth
from
specimens
in 1907 ar
specimens
Besides these, the cultures consisted of
mutants
lans. The size of 1
percentage figures.
The full name <
small
(mut. 1888 toXmut. 1895 semilata) mut. 1
lg out the fecundation of the lata specimens
by the pollen of
derived seuaratelv from one mutant
from
pollination. The seeds of the first mutant were sown in
before
from
i and 45 others which wen
)th groups were uniform
color already mentioned
like the simultaneous culture of the third
lin, and for this reason this first line h£
continued
mutant of 1008 were sown in 10 12 and
a culture of 67 flowering plants, all of which repeated the type of
their parent. Besides these, I sowed part of the seed somewhat
later in the season (June), and obtained a large group of rosettes
of radical leaves, of which, however, only one survived our long,
wet winter. This specimen flowered in 1913 on the main spike
and on a number of branches, was very vigorous, but not strikingly
stouter than the annuals of that summer.
1917] DEVRIES— OENOTHERA 7
In 191 2 I saved the seeds of 4 self- fertilized plants separately.
Two of them had been green from their first youth and the two
others had been of a pale color in the beginning. The result was,
in 1 9 13, a small but distinct advantage of the two first sowings over
the two latter sowings. I have chosen the first ones for the crosses
to be described later on, and repeated this third generation in 19 14
in order to give the plants more space and a better manured soil,
and to compare such vigorous individuals with others growing in
a dry and poor soil. The results of this comparison have been
described elsewhere; they showed that the seeds produced by the
two groups were different. Almost all the seeds of the strong plants
contained a healthy germ, but among the seeds of the weaker indi-
viduals there were about 25 per cent of empty ones. The germi-
nation showed even a larger difference, giving about 80-90 per
cent of seedlings for the normal seeds and only about 50 per cent
for those of the weaker plants. 3 I shall return to this phenomenon
in the second part of this article.
The fifth generation was derived, in 191 5, from seeds of 4 self-
fertilized individuals of 19 14, chosen as the best ones among the
stronger of the two groups. Sixty plants from one parent were
planted in my experimental garden on good soil and with plenty
of space, in order to be used for crosses. The remainder embraced
about 3000 plants (between 600 and 800 from each parent) and
were set out in another garden in order that the degree of muta-
bility of this race might be studied. It was found to be rather
small, although almost all of these plants have flowered and have
been carefully tried at different stages of their evolution, from
their germination to the time when their last flowers faded away in
August and their first fruits ripened.
The result of these repeated inspections has been that 4 mutants,
belonging to one type, were discovered, but that no other deviation
could be observed. This gives a percentage figure of o . 1 . If we
compare this with the table given on p. 337 of my Gruppenweise
Artbildung, we see that 0. blandina falls into the group of those
mutants (O. nanella and O. rubrinervis) , the mutability of which has
3 Uber kiinstliche Beschleunigung der Wasseraufnahme in Samen durch Druck.
Biol. Centralbl. 35:175. 1915. In this article O. blandina has been provisionally
designated as O. Lamarckiana mut. nov. B.
8 BOTANICAL GAZETTE [January
become much smaller than that of the parent species, which latter
is given there as 2 . 2 per cent. The transition of one or more unit
characters into the inactive condition was considered there as
the probable cause of this change, and the same conception
may obviously be applied to our present case.
Although the mutability of O. blandina is thus seen to be very
small, it does not follow that it is wholly absent for other mutations
than the one mentioned. Casual mutations parallel to those of
O. Lamarckiana may be expected to appear from time to time,
either in the pure strains or after hybridizations with other, still
less mutable, species. This has occurred once in my garden.
Among the offspring of a cross between O. blandina and O. Cocke-
relli, a species from Colorado, an individual arose in 191 5 which
showed the marks of O. lata combined with those of O. Cockerelli, and
agreed with the description given in my book (p. 254). It proves
that the mutability of O. blandina into lata is not wholly absent.
The mutation from 0. blandina, 4 specimens of which occurred
in my culture of 191 5, was a strikingly new type, quite different
from all the mutations produced by O. Lamarckiana and its deriva-
tives until now. It was distinguished at once by its linear leaves,
which could be seen in the boxes before the young plants were
planted out on the beds. The 4 mutants were brought into the
glass-covered part of my garden, where 2 of them have flowered.
The 2 others remained small, produced stems, but died in the fall
before making any flower buds. Of the flowering specimens one
was also small and therefore was not used as a seed-bearer, but the
other reached about 1 m. in height, was very richly branched, and
bore, from July to October, many hundreds of flowers and fruits.
All these flowers had the same type, consisting of narrow petals
instead of the large cordate ones of the parental form. The petals
did not belong to the type called cruciata, inasmuch as they had not
the least sign of the sepalody characteristic of O. cruciata and its
allies. Their color was uniformly yellow, not differing from that
of O. Lamarckiana. The breadth varied from 0.5 to 1.5 cm. for
a length of 3 cm. The form was ovate, with some small indenta-
tions along the margin, and the tip was narrowed and more or less
spirally twisted. This latter mark, which was best visible during
1 9 1 7] DE VRIES— OENOTHERA
9
the time of the most abundant flowering, has induced me to choose
for this mutation the name of 0. spiralis.
As to the other marks, they were probably all evolved under
the influence of the very narrow leaves, which could not produce
food enough for very stout individuals or organs. The leaves
measured 5-6 mm. in breadth by a length of 8-10 cm.; they were
smooth (without bubbles) as in the parent, not folded longitudi-
nally, only a little hairy, and dark green. The internodes were
% long, reaching 2 cm. or more, and the foliage was therefore thin and
the whole habit slender. The flower buds were less hairy than in
0. blandina, but more so than in 0. Lamarckiana, and broader than
would be expected from the narrow petals. The stigma was above
the anthers, which contained a good supply of pollen, making
artificial self-pollination and crossing: quite easy. The fruits were
thin
more
It should be pointed out that the origination in 4 specimens,
one from one parent and the 3 others together from another parent,
is analogous to the production of 0. blandina itself, which arose in
3 specimens from one lot of seeds. It points to an internal condi-
tion of heritable mutability and suggests the expectation that
under a better climate and with more suitable conditions of culti-
vation the number of simultaneous mutations in the same direction
might increase sensibly.
Crosses of O. blandina with other species. — In order to
give proof that 0. blandina is really the mutant velutina, I made
some crosses with such species as are known to split 0. Lamar ck-
iana and some of its other derivatives into the twin hybrids laeta
and velutina. It is obvious that with the loss of the active qualities
must
The
must
give
In other words, the crosses with these species must be expected to
must
crosses
0. Lamar ckiana .
io BOTANICAL GAZETTE [jaxuarv
Under normal conditions the splitting of this latter species occurs
in nearly equal groups of both the twins, but as a matter of fact
the external circumstances are, with us, often such as to diminish
the percentage of laeta quite sensibly. These deviations, however,
have been amply studied in my work on Gruppenweise Artbildung;
they show what size the cultures must be in order to prove the
absence of laeta. I cultivated 60-80 offspring for each culture, and
repeated the same cultures during 2 years, making on the average
140 specimens for each cross. The first year I compared them with
the hybrids laeta and velutina derived from the corresponding
crosses of my new dimorphic mutant O. cana* which happened to
be at hand in a complete set; but the second year I have sown the
twin hybrids issued from crosses of 0. Lamarckiana itself with the
same species as were used for the crosses of O. blandina. The
material is externally the same in both cases, and quite as good for
the comparison, but in the latter instance the proof is a more direct
one. I grew the hybrids of O. blandina and the control cultures
side by side, and compared them from the beginning of germi-
nation in February until the ripening of the first fruits in Septem-
ber. The differences between the two twins of a cross are large
and striking, 5 from their very first leaves, and it was therefore
impossible that a laeta among the hybrids of 0. blandina could have
escaped observation. As a matter of fact, no single laeta appeared,
although altogether over 500 hybrids were cultivated.
For these crosses I chose 2 heterogamic and 2 isogamic species,
and made the combinations in both groups in the opposite direc-
tions, so as to use 0. blandina twice as a pistil and twice as a pollen
parent. I made these pollinations in 1913, in the third generation
of my race, choosing the most vigorous individuals which had had
a normal green color from their very youth. The crosses with the
heterogamic species were O. syrticola Bartlett 6 XO. blandina and
0. blandinaXO. biennis Chicago. Those with the isogamic forms
*De Vries, Hugo, New dimorphic mutants of the Oenotheras. Bot. Gaz.
62 : 249-280. j£g,y. 5. 1916.
s For descriptions and photographs as well as for colored plates of the twins, see
Gruppenweise Artbildung.
6 This is the O. muricata L. of my Gruppenweise Artbildung.
1 9 1 7 ] BE VRIES—OENO THERA 1 1
were 0. HookeriXO. blandina and O. blandinaXO. Cocker elli. 1
These combinations would have given the twins laeta and velutina
if O. Lamarckiana had been used instead of 0. blandina. Now.
however,
showing
mutant
From
only
in the velutina condition. The former
as a cure mutant
8
I shall now describe the single crosses as briefly as possible.
O. syrticolaXO. blandina was made on 2 biennial plants of the
first named species in July 19 13, the pollen of a green blandina being
used in the one case, and that of a pale green one in the other case.
The seeds of the first one were sown in 19 14, those of the other in
191 5. Both of them gave cultures of 70 healthy offspring, making
specimens
fruits
com
June, before flowering. They were
1 9 14 with the twins of O. syrticolaXO. cana, and in 191 5 with those
from a cross of O. svrticolaXO. Lamarckiana. made in 101^ on a
evidently
specimen of the same group of biennial plants a;
with 0. blandina. All of the 140 hybrids were
and exactly like those of the control cultures.
O. blandinaXO. biennis Chicago. — This cross was made on two
specimens of 1913, the pollen of the same parent plant being used
in both of them. They gave uniform cultures of 60 and 80 plants,
of which 25 and 10 were allowed to make long spikes of flowers and
fruits. The others were annual plants also, but were thrown away
in June, as soon as they reached a height of 30-40 cm., and showed
their marks so as not to leave the least doubt concerning their
velutina qualities. In 19 14 I compared them with the hybrids of
0. canaXO. biennis Chicago, and in 19 15 with th
first
figures of these species
course
admitted to be possible. As a matter
see
Grupp
12 ' BOTANICAL GAZETTE [january
second, from
indi
viduals of all these crosses reached, in September, a height of more
m
of their evolution, like the velutina of the controlling cross.
O. blandinaXO. Cockerelli. — Seeds of only one cross of 1913
were tried, both parents being annuals. One part was sown in
1914, another in 191 5; size of the cultures, 60+80= 140 specimens,
of which 25 and 21 flowered. One of the latter was the lata mutant
previously mentioned. In June 19 14, there was not the least doubt
concerning the identity of all the 60 specimens with O. (canaX
Cockerelli) velutina, but in 19 15 those young plants which had not
been planted out in order to flower were a little too crowded.
I therefore pulled out those which were indubitably velutina, and
planted all the dubious ones on a separate bed, giving them just
as much space as in ordinary cultures. About one-half of these
(11 plants) flowered in September, but all of them displayed, at
that time, the characters of 0. (Lamar ckianaXCockerelli) velutina,
so as to leave no room for doubt. No laeta has appeared among
the offspring of this cross.
0. HookeriXO. blandina. — Only one Hookeri was crossed in
1 9 13 with one specimen of blandina of my race. The seeds gave
60 offspring in 1914 and 85 in 191 5, of which 25 and 10 flowered.
In the crosses of O. Lamarckiana and its derivatives with this
Californian species, the velutina have almost the features of 0.
Hookeri itself, showing only a small influence of the other parent.
I compared my hybrids in both years with first generation hybrids,
using for the comparison both the reciprocal crosses of O. cana of
1913 in one year and the hybrids of a cross 0. HookeriX Lamarck-
iana of 1909 in the next year. Although the specimens, which were
not allowed to flower, made stems of only a few centimeters, or
0. Hookeri was strongly pronounced in them. All of them
long narrow leaves of velutina , and no laeta occurred in tl
culture of 145 plants.
Resuming these details, we see that 565 hybrids of O. i
with splitting species have been studied, and that all of th
type of
the
crosses of 0. Lamarckiana and of 0. cana.
t
i9i 7] DeVRIES— OENOTHERA 13
Crosses of O. blandina with O. Lamarckiana. — If the laeta
qualities have become latent and inactive in O. blandina, we should
expect that this mutant would have acquired the property of
splitting itself these qualities in O. Lamarckiana. The confirma-
xpectation must
from
mutants
may give rise to the same hybrid twins as the parent species, we
may expect O. blandina to split them also. I made both the
reciprocal crosses with the parent species and one with the dwarf,
and all 3 cases have corroborated my conception. I made the
crosses in 19 13 in the third generation of my race, and cultivated
the first generation in 19 14, repeating it in 1915. The splitting
occurred in all 3 cases as expected, giving nearly equal groups of
the two types. One of these types exactly corresponded to O.
blandina itself; in comparing it from its first youth up to the time
of flowering and fruiting, I could not discover any difference.
This one should be considered as the velutina, therefore, and will
be called 0. (Lamar ckianaX. blandina) velutina a.s.o. The other
type was evidently a laeta. During some stages of its evolution
it was almost wholly like O. Lamarckiana, but later it changed its
appearance and displayed some of the characters which usually
distinguish the different forms of the hybrid laeta from their parents.
For this reason I shall call it O. (LamarckianaXblandina) laeta, or
briefly O. blandina laeta, implying by this name only the presence
of one or more characteristics of the laeta type, but not necessarily
all of them.
According to the species which determine the splitting in
O. Lamarckiana, the types of hybrid laeta may be divided into two
groups. One of them is small-flowered and ordinarily tall, corre-
sponding to the rigida type described and figured in my book
(PP- 73, 80, 81). To this type appertain the laeta produced by
O. biennis, O. muricata, 0. Cockerelli, and 0. biennis Chicago. The
typ
embraces only the O. (H
Lamarckiana) laeta and its reciprocal. The flowers have the same
size in both parents, and therefore this size is not changed in the
hybrids. In the cross of O. Lamarckiana and O. blandina the same
rule prevails, the flowers of the hybrid being not rarely even some-
what stouter than those of the parents.
H
BOTANICAL GAZETTE [january
0. blandina laeta shows the greatest affinity to 0. Hookeri laeta,
not only in the flowers, but also in other respects, as, for example,
in the stature at the time of flowering, which in both hybrids comes
much nearer to that of O. Lamarckiana than any of the small-
flowered hybrid laeta. Far more interesting, however, is the simi-
larity in its behavior in the second generation, after self-fertilization.
The Hookeri laeta are the only laeta as yet known to split; all laeta
of other extraction and all the velutina as yet studied give a uniform
progeny. But the Hookeri laeta split in every generation into
laeta and velutina which are exactly like the original twins. 9 The
same phenomenon is seen in O. blandina laeta , although as yet I have
only cultivated one second generation from one cross. This was
O. blandinaXO. Lamarckiana , made in 19 13. The first generation
in 1914 gave 59 per cent velutina and 41 per cent laeta, and the
progeny of the latter split into the same two types in 191 5, giving
67 per cent velutina and 3$ per cent laeta. Why the large-flowered
laeta should split, but the small-flowered type remain constant, is
a question which will have to be studied later.
O. blandina laeta has been, throughout its whole evolution,
exactly the same type in the 3 crosses already mentioned, and whose
progeny I cultivated in both years side by side. In the seed pans
and the transplanting boxes the young plants are almost exactly
like O. Lamarckiana, resembling this form far more than any of the
hybrid laeta do. This condition prevails until the beginning of
flowering, during which period the leaves of the stem are somewhat
broader and less covered with bubbles than in the parent species.
This difference is then seen to increase gradually and becomes
evident in the lower bracts of the inflorescence, which are broad,
especially at their base, smooth, and wholly or almost without
bubbles. As the spike develops, the difference from the parental
type becomes greater. The fruits are less crowded and somewhat
stouter, and the plants gradually reach a greater height than
specimens of O. Lamarckiana planted at the same time and under
the same conditions. Although the differences are still small,
apart from the smoothness of the leaves, the plants of O. blandina
laeta cannot be mistaken for Lamarckiana during all the time of
flowering, which may last more than 2 months.
' See the pedigrees in Gruppenweise Artbildung, p. 131.
1917] DeVRIES— OENOTHERA 15
It seems probable that the increased breadth and the dimin-
ished bubbles of the higher leaves of the stem and of the bracts of
the inflorescence are expressions of a single change, which must
consist in a thorough stretching of the blade parallel to its surface.
If this be so, we may conclude that the bubbles, which are so
characteristic of O. Lamarckiana, are due to some deficiency in this
stretching and thereby constitute a recessive character. If this
conclusion be granted, the smoothness of the leaves of O. blandina
must be dominant in its crosses with 0. Lamarckiana, and in this
way be transferred to both of its twins, causing the one to be a laeta
instead of a pure Lamarckiana. We are thereby provided with
a beginning of an experimental analysis of the marks of mut.
velutina, as already discussed.
Here I might insert some considerations concerning the mutative
origin of O. blandina. We have seen that 0. Lamarckiana and
O. nanella, when crossed with this new form, repeat its characters
in part of the offspring. In the same way a mutant velutina may
be produced by the conjugation of a mutated sexual cell with
a normal one. Thus it is not necessary to assume the accidental
meeting of two mutated gametes, which would obviously make the
chance of the mutation occurring very much smaller still. It is
sufficient to suppose that only the female elements of the original
O. laeta have mutated in this way, although we cannot know whether
this change might not have taken place in the male cells. And
since O. blandina behaves as an isogamous species, both hypotheses
seem to be equally probable. In both cases mutants of the laeta
type should be expected to appear also, but as they would be very
rare and not discernible in the beginning from the Lamarckiana
specimens which always develop out of a part of the seeds of 0. lata,
they would surely have been overlooked in the years 190 7- 1908,
when the mutation into blandina occurred.
I shall now give a more detailed description of my experiments.
The crosses were made in 19 13 and the first generation was culti-
vated twice for every cross, once in 19 14 and once in 191 5.
O. blandinaXO. Lamarckiana. — A biennial specimen of the
latter form was chosen and its pollen placed on the stigma of two
individuals of the thoroughly green type of 0. blandina. The seeds
of one cross were sown in 19 14, and those of the other in 191 5.
16 ' BOTANICAL GAZETTE [january
The first culture consisted of 23 laeta and 34 velutina, making a
total of 58, with 41 per cent laeta. In 191 5 the figures were 46
laeta and 39 velutina, or 54 per cent laeta in 85 specimens. Although
the size of the cultures was small, they evidently point to a division
in nearly equal groups. The two types were clearly different from
the beginning and could easily be counted out in June before the
production of the stems. In 191 5 I separated them in March, at
the time of planting into the boxes, in order to control my esti-
mate later on, and in April planted the laeta in one group and the
velutina in another half of the bed. In 19 14 I had 25 and the
following year 10 flowering plants, half of which belonged in each
case to the laeta type and the other half to the velutina type. The
laeta have already been described; the velutina were in no respect
and at no time different from ordinary O. blandina.
The second generation from seed of one of the velutina plants
embraced 30 flowering and 40 younger specimens, all of which
exactly repeated the marks of their parent. From the seeds of one
self -fertilized laeta, however, I got the splitting group already
described. Its two types were the same as in the previous gen-
eration. I recognized the splitting in the seed pan, but counted
them only in June after planting out 15 laeta and 15 velutina. All
in all I had 80 plants, of which 26 were laeta and 54 velutina, or
33 per cent laeta, which is somewhat less than in the first generation.
All the 30 specimens of the bed richly flowered and ripened their
first fruits before being thrown away.
O. LamarckianaXO. blandina. — A biennial plant of the species
was crossed in 19 13 with a green individual of the mutant. The
seeds were sown partly in 19 14 and partly in 191 5. They gave
the same two types as in the reciprocal cross. During the whole
lifetime there were no visible differences. In the first year I had
60 plants with 22 per cent laeta, and in the second year 108 speci-
mens with 25 per cent laeta; the remainder were velutina.' Of
these, 25 and 10 flowered, in about equal groups for both types,
having been recognized and sorted out at the time of planting.
The other plants were cultivated till the end of June.
O. blandinaXO. nanella. — Two green individuals were ferti-
lized in 1 9 13 by the pollen of my race of O. Lamarckiana mut.
1917] DeVRIES— OENOTHERA 17
nanella; the seeds of the one were sown in 19 14 and of the other
in 191 5. There were no dwarfs in this first generation, but only
laeta and velutina, which were just like those of the crosses already
described. I had 90 and 72 plants, with 74 and 67 per cent laeta.
There were 25 and 10 flowering plants belonging equally to the two
groups; the others were large rosettes in June.
If we compare the percentages of laeta given with one another we
find for O. blandinaXO. Lamarckiana 41 and 54 per cent, for the
reciprocal cross 22 and 25 per cent, and for the experiment with
the dwarfs 74 and 67 per cent; finally, for the second generation of
the first cross 33 per cent. The average of all these figures is 45
per cent laeta , which comes as near to equality of the two groups
as may be expected. The deviations from this mean are probably
due mainly to the choice of the parents and to their cultural condi-
tions.
O. rubrinervis XO. blandina. — besides the 3 crosses already
mentioned and discussed, I have also made the two reciprocal
crosses with my race of 0. rubrinervis. In the first generation they
split in the same way, the only difference being that instead of
the laeta another type arises. This is the subrobusta, which appears
in the hybrid splittings of O. rubrinervis with other derivatives of
1
O. Lamarckiana, as described in my Gruppenweise Artbildung.
No differences were observed, although the comparison lasted from
germination till the ripening of the fruits. The other type was the
same as in the crosses already dealt with, and exactly like the
parental type of O. blandina.
The cross was made in 19 13 between an individual of my pure
race of O. rubrinervis and a specimen of the third generation of
0. blandina. One part of the seeds was sown in 1914 and another
in 191 5. In the first year I had 60 plants with 32 per cent blandina,
and cultivated 18 laeta and 7 blandina until the ripening of their
fruits. In the last named year I had 77 specimens, of which 61
per cent were blandina and of which 5 laeta and 5 velutina were left
to flower. All in all, the cultures embraced 137 plants, with 45
per cent blandina. The others were all subrobusta and not different
from the subrobusta cultures of those years resulting from other
crosses.
18 BOTANICAL GAZETTE [january
O. blandinaXO. rubrinervis. — For this cross I used two speci-
mens of 0. blandina of the third generation in 19 13, the one being
a pale green and the other a normal color. In 19 14 each of the
cultures embraced 60 plants, of which 25 flowered. The percent-
ages for blandina were 48 for the green, but only 20 for the pale
parent. For this reason I repeated the latter culture in 191 5 and
obtained from 70 plants 47 per cent blandina. The types of sub-
robusta and velutina in these cultures w r ere exactly the same as those
from the reciprocal cross.
The percentages given are obviously of the same type as those
for the splitting into laeta and velutina and come as near to equality
for the two types as may be expected under ordinary conditions of
cultivation. I propose to grow the second generation next summer.
The viability of the seeds of O. Lamarckiana mut. velu-
tina. — Besides the external differences between our new mutant
and the parent species, there is another mark which lends a high
interest to the new form. This is found in the seeds. The seeds
of O. Lamarckiana differ from those of almost all other species (with
the exception of 0. suaveolens) in containing a large proportion of
empty grains, even under the most favorable conditions of life.
More than one-half of the seeds have no germ at all, although
externally they are, as a rule, not distinguished from the normal
ones. Renner 10 has studied the development of these empty
seeds and found that their germ is fecundated and undergoes one
or two cell divisions, but then stops and dies off. He considers this
phenomenon as a hereditary character of the species. It runs
parallel, in this respect, to the rudimentary ovules described by
Geerts, which are characteristic of the whole group of the Oeno-
theras. Besides this type of empty seeds a less or larger number
usually occur which stop their development at a much later stage.
The proportion of these can be diminished by a better culture,
and therefore they may be considered as a result of the crowding
of the seeds in the capsules, combined with the limited amount of
nourishment available for them.
Our new mutant velutina produces hardly any abortive seeds,
at least under normal conditions of culture. I tried the seeds from
10 Renner, O., Befruchtung und Embryobildung bei Oenothera Lamarckiana.
Flora 7:115-150. 1914,
i9 1 7] DEVRIES— OENOTHERA 19
purely pollinated capsules of 4 specimens of my culture of 191 5,
which was the fourth generation of my race. I took them carefully
out of the fruits, mixed those of 5 successive capsules of the same
spike, and counted 200 grains from each lot. I soaked them in
water, pushed this into their seed coats by means of a pressure of
8 atmospheres for about 24 hours, and afterward laid them out to
germinate in small glass tubes in a stove at i<
C. rr Within
the larger part of the seeds germinated, giving percentages of
85, 84, 73, and 70 for the 4 lots. I then opened the remaining
grains and found fully developed germs in almost all of them.
The percentage of germs, being the sum of the two trials, came to
99, 96, 96, and 93, and there is no doubt that if they had been left
in the stove for a longer time, almost all of the resting germs would
have shown signs of germination.
The proportion of rapidly germinating grains and that of empty
ones depend in a high measure upon the external conditions of life.
During the summer of 19 14 I cultivated 2 lots of individuals from
seeds of the same parent plant, giving to one of them the ordinary
favorable conditions of my garden, and keeping the others in a dry
soil without manure. The seeds of the 2 most vigorous specimens
of both lots, taken from self-fertilized capsules, were tried. They
contained 99 and 99 per cent of germs for one group, but only 72.5
and 7*. c ner cent for the. other oroun. The
same
the amount of grains which germinated within the first
ie figures were 80-88 per cent in one case and 53 per cer
other
case.
12
hereditary property of producing about
mutation
the visible changes in the external structure. The same
accompanies the mutation into gigas, rubrinervis, and some n
lata
0. scintillans, 0. cana* and
J method has been followed in all the experiments to be described in the text.
It is described in the following papers; The coefficient of mutation in Oenothera
biennis L.
kiinstliche Beschleunigung
Wasseraufnahme in Samen durch Druck. Biol. Centralbl. 35:161-176. 19*5-
"Biol. Centralbl. 35:174-175, where 0. blandina was provisionally indicated as
mut. nov. B.
20
BOTANICAL GAZETTE
[JANUARY
I made a series of crosses in order to study the nature of this
latent mutation of O. blandina. They led to the discovery of some
points which seem to deserve a more thorough study than I could
give them until now.
In the first place, it is to be expected that in crosses with those
species which do not produce such empty seeds the high figures of
both parents will simply be repeated. I tried these cases, deter-
mining the amount of normally developed germs in lots of 200 seeds
each, after the method already described. I made the crosses in
1914 and 1915, and in most cases in both the reciprocal directions.
The seeds were taken from 5 successive fruits, and carefully pre-
pared so as not to lose any small grains. The results are given
in table I.
TABLE I
Cross
Percentage of germs*
Cross
Cross
Reciprocal
O. biennis Xblandina
O. biennis Chicago X "
0. Cockereili X "
0. Hookeri X "
O. syrticola X "
99
95
99
94
87
89
95
91
83
91
94
87
* The dash ( — ) means that the cross has not been tried.
some
in 191 5 and tried their seeds after self-fertilization. I got almost
the same figures: O. blandinaXChicago 86 per cent, 0. HookeriX
blandina 97 per cent, and O. syrticolaXblandina 93 per cent.
In trials with other species the hereditary property of O.
na of making germs in only one-half of its seeds :
normal condition of producing almost only norma
3 in the same way in crosses with O. blandim
The
results are given in table II.
be expected that those mutants
<es give high percentages after self-fertilization will do the same
:heir crosses with the velutina mutant (table III).
The crosses were made in 1915. O. rubrinervis is the same
used in my Grupp
O. erythrina is
mutant from Lamarckiana, of the type of the hybrid form
ista of that book; and 0. deserens is a mutant from 0. rubri-
t^m
'9i7l
De VRIES— OENOTHERA
21
nervis, originated through the loss of the typical red color, but
without change in the brittleness of the stem. These new mutants
will have to be dealt with in another article.
TABLE II
Cross
Culture
O. blandina
a
XLamarckiana. . . .
s\ . . . .
X nanella .
O. LamarckianaX blandina
1914
1915
1915
1914
Percentage of germs
94
97
99
90
Reciprocal
95
The most interesting question in this situation, however, is
that concerning the seeds of the first generation of the crosses
between O. Lamarckiana and 0. blandina. I made the crosses in
TABLE III
Cross
Percentage op germs
O. blandina X rubrinervis
u Xerythrina. ,
u X deserens . .
Reciprocal
97
100
1914, cultivated the hybrids in 1915, and tried their self-fertilized
seeds during the winter. From each of the 3 crosses I had 5 vigo-
rous specimens of the laeta type, and an equal number of the
velutina type. I shall deal with the laeta first (table IV).
TABLE IV
Self-fertilized seeds of laeta specimens of the first generations
Cross
■— 1 % _ ,
O. LamarckianaX blandina. . . .
O. blandina XLamarckiana
" ■ XnaneUa
Percentage of germs
97
96
95
95
92
36
43
4i
39
The 3 crosses may be taken as instances of one type and com-
bined on this ground. We see that a splitting occurs, n indi-
viduals having the high percentages of the one patent, and 4 others
/
22
BOTANICAL GAZETTE
(JANUARY
having the low figures of O. Lamarckiana. This splitting may be
considered, therefore, as amphiclinous, 13 73 per cent of the hybrids
belonging to the one and 27 per cent belonging to the other parental
type. The splitting is analogous to that of the cross O. Lamarck-
ianaXnanella, which gives, under ordinary circumstances, in the
*
first generation about 78 per cent tall and 22 per cent dwarfish
specimens. It must be pointed out, however, that here the germs,
which belong to the next generation, are dealt with as a mark of the
first generation. In this respect they may be compared with the
rudimentary ovules of Geerts, which are not fertilized.
I tried also the blandina plants of the same crosses, but had
fertilized only two specimens of each, which is too few to study
this phenomenon. I found 77 and 69 per cent, 67 and 60 per cent,
and 71 and 70 per cent of good grains among their seeds. It is
remarkable that all of these plants had about the same figure, which
is far less than that of the specimens of the pure race of O. blandina
(about 95 per cent), but a splitting did not show itself.
The same difference as between the laeta and extracted velutina
was shown by the subrobusta and the velutina from the crosses with
O. rubrinervis. I found the figures as given in table V.
TABLE V
Cross Hybrid
Percentage of germs
0. rubrinervis X blandina
subrobusta
m
blandina
a
97
96
70
80
96
96
68
75
0. blandina Xrubrinervis
96
0. rubrinervis X blandina
z? v
0. blandina Xrubrinervis
m
It is possible, however, that this difference is only an effect of
the higher exigencies of the plants of the type of blandina y since we
have already seen that their amount of good grains is easily dimin-
ished by an unfavorable culture. Moreover, this character is not
a constant one, for in trying the blandina plants of the second gen-
eration I found their contents of normal embryos complete, no
single empty grain being found in lots of 200 seeds of two such
plants.
** Uber amphikline Bastarde. Ber Deutsch. Bot. Gesells. 33:461-468. 1915.
1917] DeVRIES— OENOTHERA 23
It is necessary, of course, to study the progeny of the laeta
plants with a high and of those with a low percentage figure.
Until now, however, I have had only an opportunity to study the
offspring of one laeta of the first type, since I happened to have
fertilized only that one in 19 14. Its seeds contained 96 per cent
of germs. I cultivated 15 specimens of laeta from these seeds, and
found, for self -fertilized seeds of each of them, percentages between
91-97, with a mean of 95. In this instance, therefore, the high
percentage seems to be constant.
The main result of this inquiry is that O. Lamarckiana mut.
velutina has lost the property of the parent species of producing
about one-half of empty grains, that this property is recessive to
the normal production of almost only good grains, and that a split-
ting is observed in the first generation, which seems to follow the
type of amphiclinous hybrids, as in the case of O. LamarckianaX
0. nanella. A further study is required to elucidate these points,
especially the behavior of the seeds as a mark of the generation
which produces them.
Summary
1. O. Lamarckiana mut. velutina = 0. blandina arose from my
family of 0. Lamarckiana mut. lataXsemilata among seeds of the
third generation saved in 1904, in 3 specimens. Of one of these
I cultivated a second generation and of one of the others 4 suc-
cessive generations, embracing together over 3000 plants.
2. All these plants were exactly alike with the exception of
4 mutants which constituted a new type, O. spiralis. The muta-
tion coefficient was 0.1 per cent, or about the same as for O.
rubrinervis and O. nanella, and much smaller than that for
0. Lamarckiana.
3. For the appearance of the original mutation only one sexual
cell needs to be mutated, since in combining with a normal gamete
it may give rise to 0. blandina, as is shown by the splitting of both
the reciprocal crosses of this form with 0. Lamarckiana. The
into nearly equal groups of specimens like
and
4. 0. Lamarckiana mut. velutina resembles the hybrids of the
>e of velutina so much as to be considered one of them. Among
24 BOTAMCAL GAZETTE [january
them it is the most like 0. (LamarckianaXO. biennis Chicago)
velutina, without the marks of the second parental species, however.
It is slender, with long internodes in the spike, and with flowers as
large as those of O. Lamar ckiana.
5. 0. Lamar ckiana mut. velutina is distinguished from its parent
species in a very striking character. It has lost the property of
producing about one-half of empty grains; almost all of its seeds
contain healthy and well developed germs and germinate easily.
This new quality is dominant over that of the parent. It is the
same as in almost all the older species of the genus.
6. Moreover, O. mut. velutina is distinguished from O. Lamarck-
iana at least in one other dominant character, the smoothness of
its leaves at the time of flowering. Secondly, it is distinguished
in quite a number of characters, which seem to be more or less
independent of one another, namely, slender stature, long inter-
nodes of the flower spike, narrow and longitudinally folded leaves
and bracts, and cup-shaped flowers. Besides these, the richness
in red color and the hairiness of all organs, especially in their youth,
are very striking marks.
7. In crosses with those species which split O. Lamar ckiana and
some of its other derivatives into the twin hybrids laeta and velu-
tina, the O. mut. velutina produces only hybrids of the velutina type.
8. In crosses with O. Lamar ckiana and O. nanella, these forms
are seen to be split by O. mut. velutina into twin hybrids, which
correspond to the twins produced by other species with them, but
which, of course, lack the characters of those other parents. The
twins of 0. blandina may be considered as pure laeta and pure
velutina, therefore, the former having smooth leaves and bracts
in the summer, the latter being identical with O. blandina itself.
9. The study of our new mutant reveals the existence of at least
two recessive characters in 0. Lamarckiana, namely, the bubbles
of the leaf blade and the presence of typical empty seeds.
Botanic Garden
Amsterdam
EXPLANATION OF PLATE I
At the right, Oenothera Lamarckiana mut. velutina (O. blandina) ; at the
left, O. blandina mut. spiralis.
BOTAMCAL GAZETTE, LXIII
ELATE I
Di \ RIES on <>i AOIIfKRA
INFLUENCE OF THE LEAF UPON ROOT FORMATION
AND GEOTROPIC CURVATURE IN THE STEM OF
BRYOPHYLLUM CALYCINUM AND THE POSSIBIL-
ITY OF A HORMONE THEORY OF THESE PRO-
CESSES
Jacques Loeb
(with thirty figures)
In two former publications 1 it was shown that while the stem
of Bryophyllum calycinum prevents or retards the development of
roots and shoots in the notches of a leaf, conversely the leaf acceler-
ates the development of roots and shoots in a stem ; since in a stem
deprived of all leaves the roots and shoots develop later and grow
more slowly than if a leaf is left on the stem. The two phenomena
found a common explanation in the assumption that the leaf
furnishes substances to the stem which accelerate the organ forma-
tion in the latter, while if these substances are not "sucked away"
from the leaf by the stem they will accelerate the growth of roots
and shoots in the notches of the leaf. These substances may be
water or solutes.
In these experiments it was noticed that the leaf has also an
accelerating effect upon the geotropic curvature of the stem.
When stems of Bryophyllum are suspended horizontally by 2
threads in a jar saturated with water vapor, they will bend, becom-
ing convex on the lower, and concave on the upper side (fig. 1),
and this bending continues until finally the stems assume the shape
of a U. This geotropic bending is a slow process when the stem
contains no leaf, but is considerably accelerated if a leaf is left on
the stem (fig. i). The position of the leaf has a great influence,
not only on the velocity of the geotropic bending and the region of
the stem in which it occurs, but also upon the formation of organs
in the stem. The description of this influence and of the appar-
ently close connection between the two groups of phenomena will
form the subject of this paper.
j Loeb, J., Bot. Gaz. 60:249-276. 1915; 62:293-302. 1916.
25]
[Botanical Gazette, vol. 63
26
BOTANICAL GAZETTE
[JANUARY
cm. long, were selected for these
and the
2
nodes
Straight stems,
experiments. The
removed, the pieces chosen for experimentation containing about
4-7 or 8 nodes. Each stem was suspended horizontally by 2
threads (fig. 1), one at each end, in a jar the bottom of which was
filled with water.
The jar was loosely
wi
so that the stems were surrounded by an atmosphere almost com
pletely saturated with water vapor*
Fig. i
their growin
her surprised to find that stems deprived of
should show geotropic curvatures. These
curv
(%. 1)
the stem, both nodes and internodes, bent
We shall see later that the bending was accom
an increase in the length of the
the
stem, while the upper side of the stem
quence of this growth.
1917]
LOEB—BR ] OPH YLL UM
27
I. Influence of the presence and absence of leaves
Fig. 1 illustrates the influence of the presence and absence of
curvature
The
stems to the right had no leaves and bent very
other leaves were removed) and bent much more
(while
The
photograph was taken on the eleventh day after the experiment was
begu
It is noticeable also that the stems containing leaves
Fig. 2
formed roots (in their basal nodes) much more rapidly than the
stems deprived of all leaves. This experiment, representing the
accelerating influence of the apical leaves upon both root formation
and geo tropic curvature, never fails; and the same may be said of
most of the experiments described in the following pages.
11. Influence of the position of the leaf on the stem upon
geotropic curvature and organ formation
In the following experiment only one leaf was left on the stem.
It was found that it made a great difference whether this leaf was
at the apex or at the base. This is illustrated by fig. 2. On the
2S
BOTANICAL GAZETTE
[JANUARY
hand in the photograph are 6 stems havin
the apex,
reached <
the base.
stems
stems having
this case the curvature is generallv much
/
/
/
*
/
Fig. 4
when the leaf is at the apex. Both groups of stems had been sus-
pended horizontally and both had been put into the jar at the same
time. The photograph was taken on the eleventh day. This
experiment also is always successful.
1917]
LOEB—BRYOPHYLLUM
29
It is noticeable, incidentally, that while the leaf at the base
accelerates the shoot formation, the one at the apex accelerates
root formation. The more rapid geotropic curvature occurs in
those stems in which the root formation is favored.
Aside from the influence of the position of the leaf upon the
velocity and extent of the curvature, an equally striking influence
exists between the position of the leaf and the localization of the
curvature
When the leaf is at the anew, the curva
I
Fig. 5
ture appears near the second node behind
asally from) the leaf (figs. 3, 4), and is
confined chiefly to this region and possibly
to the next node located more basally.
The drawing was made 10 days after the
experiment began.
Figs. 5, 6, and 7 are drawings of stems
with one leaf left at the base suspended in
the same jar simultaneously. In this case
little curvature takes place and the curva-
hich
Fig. 6 is an extreme case. It
increases with the length of the pi
basal leaf. The photograph in fig
the localization of curvature accor
at the apex or at the base.
In the experiments thus far men
is near the region where the leaf is located.
It seems that the amount of curvature
also
of the
When the leaf is left on the upper
3°
BOTANICAL GAZETTE
[jAN'U AR Y
horizontally suspended stem, the geotropic bending is slower than
when it is on the lower side, but the bending will also be much more
rapid and more intense when the leaf is left at the apex (figs. 8, 9,
10) than when it is left at the base (figs. 11, 12, 13). In the latter
case the bending is again slight, and what little curvature occurs
is confined to the immediate neighborhood of the basal leaf. Fig. 13
is an extreme case. If the leaf is at the apex,
curvature.
the curvature takes
of the second node or behind (basally from)
the second node.
ft
A study of these stems revealed a remark-
able correlation between root formation and
stated already
when the leaf is located at the apex it favors
root formation in the rest of the stem, and
when it is at the base it favors shoot forma-
tion but inhibits root formation in the whole
stem located apically
■
the leaf.
agrees with the idea that the leaf sends root-
forming substances toward the base and shoot-
forming substances toward the apex. We notice that the geotropic
curvature is favored or accelerated most in those stems in which
an apically located leaf is left, and in such stems root formation is
favored also. The correlation between root formation and geo-
tropic curvature is still more striking, however, if we consider the
location of the roots formed- When the leaf left is at the apex,
1917]
WEB— BR YOPH YLLUM
3*
obvious in r, figs. x. 4, 8, 0. and
the second (and often the fourth) node
>ic curvature also begins. This is
When the leaf left
base, the root formation is considerably less (as
curvature) , and what there is of root formation
mam
basal node
When
namely,
base, root formation is more favored when the
\
\
I
1
is below, as in figs, n, 12, and 13, than when it is
appeared as yet in the leafless basal node on the
upper
series of experiments
were started simultaneously.
This tendency of the roots to form more easily
in the nodes of the under side of a horizontal stem
is an important link in the chain of circumstances
connecting root formation and geotropic curvature, since the
growth causing this curvature is confined to the cortex of the
under side of the stem.
stems
in. Experiments on stems split longitudinally
order to find out the mechanism of geotropic curvature,
were split lengthwise and suspended horizontally in jars
saturated with water vapor. Each half stem had
either at the apex or at the base. Figs. 14-20 gh
the
periments on the seventeenth
\
\
>
y
Fig. io
IQI7]
WEB— BR YOPH YLL UM
33
Figs. 14, 15, 16, and 17 give the appearance of the lower halves of
the stems (that is, stems suspended horizontallv in such a wav that
I
/
/
/
Fig.
11
Fig. 12
«
Fig. 13
the cortex was below, and the cut surface above) on the seventeenth
day. When the apical leaf is preserved, the bending is rapid and
extensive, as in fig. 17. When the basal leaf is preserved (figs. 15,
34
BOTANICAL GAZETTE
[JANUARY
or it is confined to the
front of the basal leaf
(fig. 1 6). When
Fig. 14
place, more rapid and extensive than in fig. 15, but less rapid than
when the apical leaf is left, as in fig. 17. In the other halves of the
stem which were suspended with the cortex above (figs. 18, 19, 20),
practically no geotropic bending takes place, for the reason that
Fig. 15
the geotropic bending of the stem of Bryophyllum
is due, as we shall see, to the active growth of the
cortex on the lower side, which is lacking in those
halves in which the cut surface forms the lower
side, as in
18-20.
drawings
made on the seventeenth day of the experiment.
21 gives an indication of how regularly the
results described in figs. 14-17 occur.
It was of interest to study the reaction of split stems in which
the leaf was above and the cortex below. For this purpose it was
necessary to split the stem only to the apical or basal node in which
the leaf was preserved (figs. 22, 23), but not in its entire length.
1917]
LOEB—BR YOPII YLL UM
35
When the leaf is at the apex and above (fig. 22), geotropic curvature
of the stem occurs, but not so ranidlv as when the leaf is helnw-
the location of the curvature is again in the region of
and basally from the second node behind (basally from)
When the leaf is at the base and above
(fig. 23), no curvature ensues, at least for a long time.
The drawings were made on the seventeenth day.
The correlation between root formation and geo-
tropic curvature is again striking. When in a longi-
tudinally split stem the apical leaf is preserved and
the cortex below, as in figs. 18 and 22 , root forma-
tion occurs in the second node behind the leaf, in the region
36
BOTANICAL GAZETTE
[JANUARY
where the curvature also occurs. Roots appear also at the
basal nodes and sometimes at the cut basal surface of these
Fig. i 8
stems. When the basal leaf is preserved and this leaf is below
(fig. 15), no root formation takes place generally, or not for a long
Fig. 19
time at least; while when the leaf is above (fig. 23), such root
formation takes place in the basal node on the
under side of the stem opposite the leaf. When
the cortex is above and the leaf at the apex, root
formation will occur, but chiefly or most rapidly
in the basal node, and later in the next or the 2
nodes next to them (fig. 20). When the leaf is
at the base or when the stem has no leaf, no root
formation occurs in the cases where the cortex
above, at least for a long time.
Fig. 20
1
1917]
LOEB—BR YOPH YLL UM
37
iv. Mechanism of geotropic curvature in Bryophyllum
CALYCINUM
periments
definite idea concerning the mechanism of the geotropic ben
Immediately after the stems were split, marks were made
and
then the stems were suspended horizontally, one-half of the split
stems having their cortex below, the others having their cortex
Fig. 21
above. Stems with an apical leaf were used for the purpose (like
17, 20). After 10 days, when the halves with the
those in figs.
cortex below had bent strongly, the displacement of the marks
was ascertained. It was found that the marks on the halves in
which the cortex was above and which had not bent were practically
unchanged. The same was true of the marks in the non-bent
regions of the other halves, where the cortex was below; while a
growth of 15-20 per cent of the original length had taken place in
the bent convex region of those stems having their cortex below.
38
BOTANICAL GAZETTE
[JANUARY
\
Stems split lengthwise and with a leaf left at the most apical node
were put horizontally into a jar saturated with water vapor. One-
\ half of the stems w r ere put with the cortex above
\ (fig. 20), and one-half with the cortex below (fig.
17). Only the latter bent geo tropically, the others
\ showing only a slight concavity on the upper side.
which may have been partly of a geotropic char-
acter, but which more
likely was for the greater
entire!}' , due
\
\
1
1
.
»
Fig. 22
\
\
\
\
\
\
\
Fig. 23
the longitudinal direction
tendency
19 1 7] LOEB—BR YOPII YLL UM
39
experiment was begun June 2 1 and the measurements were
i July i. The original length of each piece of stem before
from
final
length could be ascertained by direct measurement. First it was
found that the length of the split stems which had been suspended
with their cortex above was not altered, as shown in table I.
TABLE I
Length of split stems placed horizon-
tally WITH CORTEX ABOVE (iN CM.)
At beginning of experi-
ment (June 20)
At end of experiment
(July i)
9.0
11. o
10. o
14.0
9.0
10.8
10. o
13.8
Obviously no growth had taken place in these halves; there
may possibly have been a slight shortening, but if this was the case
it was so small that it was within the limits of error of measurement.
An altogether different condition was found in the other halves
of the stems which had been suspended horizontally with their
cortex below. Here an increase in length was found in the bent
part of the stem, while the apical and basal ends which had not
bent were practically unaltered also in regard to length. We
designate the apical unbent region A, the central bent region of the
stem B y and the unbent basal region C. The measurements of
4 stems are given in table II (p. 40).
It is obvious that an increase in length of 15-20 per cent took
place in 10 days in the bent central region of the stem (basally from
or around the second node behind the apical leaf), while the unbent
basal and apical regions showed no distinct alteration of length.
Fig. 24 is a photograph of marked whole stems 9 days after the
beginning of the experiment. The stems had been suspended
horizontally in the jar; all had one apical leaf left. That part of the
cortex which was below had stretched, while the cortex above was
shortened. The India ink marks were 1 cm. distant and were
made at the beginning of the experiment. The photograph shows
the change in the position of the marks on the convex and concave
sides in the bent region of the stem.
4Q
BOTAXICAL GAZETTE
[JANUARY
It is highly probable, if not certain, that the increase in length
on the lower side of the horizontally placed stem takes place pri-
marily in the cortex of the bending region and not in the pith
or wood. This follows from the behavior of these 2 parts when
the cortex of a bent (split or whole) stem is removed, and the
rigidity of the cortex is compared with that of the pith and
wood taken out.
TABLE II
Stem I
Stem II
Stem III
Stem IV
Region of stem
measured
Begin-
ning of
experi-
ment
End of
experi-
ment
Begin-
ning of
experi-
ment
End of
experi-
ment
Begin-
1 ning of
experi-
ment
End of
experi-
ment
Begin-
ning of
experi-
ment
End of
experi-
ment
A : non-bent api-
cal part
B: bent central
part
3.0 cm.
4.0
2.0
3 . 2 cm.
4-9
2.0
3.0 cm.
3-0
3.0 cm.
5 7
3.0
4.0 cm.
6.0
5.0
4.0 cm.
7.0
50
4.0 cm.
4.0
4.0
4.1 cm.
4.85
C: non-bent
basal part ....
415
If we remove the cortex on the lower (convex) side of a split
geotropically bent stem, like that in fig. 17, we find that the rigidity
of the cortex in the bent region is much greater than that of the
wood or pith ; the latter appears soft in comparison with the cortex
of the bent region on the convex side of a geotropically bent stem.
It is possible also that the increase in the rigidity of the cortex in
this region may be due to a thickening of the cortex, a point which
needs further investigation. Whatever the cause of this increase
in rigidity may be, we reach the following conclusion regarding the
mechanism of the geotropic bending of a horizontally suspended
stem of Bryophyllum calycinum.
On the lower side of such a stem in a region the location of
which depends upon the presence or absence, and, in the former
case, upon the location of the leaf in the stem, the cortex begins to
grow in length (and possibly in thickness). The wood, pith, and
cortex on the upper side undergo no such growth. This increase
in length (in one region) of the cortex on the lower side leads to
a bending of the stem in which the lower side of a horizontally
suspended stem becomes convex, the upper side concave.
1917]
WEB— BR I OP II I LLUM
4i
»
Fig. 24
42 BOTANICAL GAZETTE [january
Our investigation shows that this growing region of the cortex
coincides with the region where early roots are formed. This
suggests the possibility that the geotropic growth of the cortex on the
lower side of a horizontally suspended stem is due to a cause which is
either closely associated or identical with the cause of root formation.
If we assume with Sachs that there are specific root-forming
substances, then the question presents itself whether we are not
forced also to ascribe the geotropic curvature to the existence of
specific geotropic substances or hormones; both substances having
the tendency to collect on the lower side of a horizontally sus-
pended stem; and both substances stimulating growth, the one of
roots, the other of the cortex. On the basis of such an assumption
we might understand why no or only an insignificant geotropic
curvature takes place in a split stem when the cortex is on the
upper side, the reason being that the geotropic substances settling
at the lower side find no cortex which can grow and cause geotropic
bending. This assumption will of course be a mere hypothesis
until the existence of such hormones can be demonstrated directly.
v. Further experiments on the influence of the position
OF THE LEAF UPON THE GEOTROPIC BENDING OF A STEM
When we remove the cortex on the upper or lower side of a
horizontally suspended stem of Bryophyllum calycinum (without
removing the wood and pith), an extensive bending of the stem
takes place instantly (fig. 25), the side on which the cortex is
removed becoming convex. The mechanism of this phenomenon
becomes clear on the assumption that the cortex is under a tension
longitudinally which shortens the wood and pith. If this tension is
removed on one side of the stem, the wood and pith on that side
can stretch, while the wood and pith on the opposite side are held
in check by the cortex. This leads to a considerable curvature
whereby the side on which the cortex is preserved becomes concave
(fig. 25). This curvature due to cortex tension is much stronger
than the curvature which takes place instantly w r hen we split a stem
longitudinally. In this case not only the cortex but also the wood
and pith are removed on one side of the stem, and hence the tend-
ency of this side to stretch is considerably less than if only the cor-
.
\
.
1917]
WEB— BR YOPII YLLUM
43
removed
In the former case the
stretching
force of wood and pith on the side where the cortex is removed is
lacking. Such stems show in a striking way the influence of the
position of the leaf upon the geo tropic curvature.
More than a dozen stems whose cortex was removed on
upper side were suspended horizontally (fii^s. 26, 27). Each stem
had one leaf left, one-half of the stems having the leaf at the base
the
(%
while
I. Only the
leaf at the
able
d
any geotropic bending. This shows that
the geotropic growth of the cortex must
be considerably less when the leaf is at
when it is at the apex.
Fig. 25
When the cortex was above (lie:. 2O and the leaf
the curvature due to the effect of the removal of the cortex
on one side of the stem, which takes place instantly after the
operation .
When the leaf is left at the apical end and the cortex below, as
in fig. 27, the curvature occurs again in the region of the second
node behind (basally from) the leaf; and in that node on the lower
side the first roots develop (fig. 27). These drawings were made
9 days after the beginning of the experiment. If all the leaves are
removed on such a stem it is no longer able to bend geotropically.
44
BOr.4AVC.4Z. GAZETTE
(JANUARY
vi. Further variation of these experiments
It is well known that the so-called geo tropic "stimulus" goes
around a corner, that is, around an incision. If we assume that
the so-called "stimulus" is the flow of a liquid, we need not be sur-
prised that it is able to go around a corner or around an incision in
a stem. In a former paper (see footnote i) we have shown that
I
the "inhibition" of the stem upon the growth of the notches of a
Fig. 26
leaf also goes around a corner in a leaf when incisions are made into
such a leaf; and the mysterious character of the phenomenon dis-
appeared with the recognition of the fact that the "inhibition" is
the flow of certain substances (water or solutes) from the leaf into
the stem through a system of interlinked channels which allows
a flow in a zigzag around incisions.
same conceDtion will
ain in our opinion why a geo tropic "stimulus" will flow around
ncision in a stem, the "stimulus" like the "inhibition" being
flow of certain substances through the leaf or stem respectively,
[ncisions were made into each internode of stems of Bryophyllum
stems
calycinunty at a, b, c y and d in figs. 28 and 29. The
pended horizontally in a jar saturated with water vapor
Six
1
t
1917]
WEB— BR YOPII YLLUM
45
stems
2 leaves at the basal node (fig. 29). All of the stems with the leaf
(th
unbent.
afte
remained
lavs. In
Fig. 27
time the bending of the stems with the leaf at the
apex proceeded and the stems assumed the typical
U-shape. The stems with the leaves at the base
remained unbent. The stems with the leaf at the
apex also formed roots (on the lower side of the
stem) ; the stems with leaves at the base formed
no roots or did not form them until much later.
vii. Formation of roots in passively bent stems
We have seen that in stems suspended horizontally the roots
have a tendency to form on the under side in the same region where
the bending occurs. They form also at the basal nodes, both the
upper and lower, but this fact does not concern us in this connec-
tion. The tendency of the roots to form on the lower side in that
region which becomes convex might suggest the possibility that
the root formation occurs in the convex region, not because it is
the lower side, but because the convexity in itself might in some
way favor root formation. The following experiment shows that
the roots form on the lower side of a stem regardless of whether this
lower side is concave or convex.
46
BOTANICAL GAZETTE
[JANUARY
Stems were bent passively and fixed in this bent position by
ing their ends to a piece of wood (fig. 30). Such pieces were then
suspended in
xperiments
were made a year ago, before the writer was aware of the influence
of the position of the leaf upon geotropic curvature and root forma-
tion, and in the expectation that passive bending of a stem would
lead to the production of roots on the convex side of the stem.
be
numerous
were
was concave.
order to understand the details of this
figure it should be stated that the photograph
was taken 2 months after the beginning of the
experiment. The apical part of the stem had
been horizontal in the beginning, but had since
bent upward, the bending taking place behind
the second node. The side on which the roots were formed, there-
fore, had originally been the under side. The roots formed all
along the lower side of that part of the stem which at first was in
a horizontal position. Besides the small apical leaves, a large older
leaf had been left on the stem, and from this leaf the stem was
suspended. At the base of this large leaf and of the next 2 nodes
a strong root formation took place. This is what we should expect
on stems in which a leaf is left on the upper side.
Fig. 30 also illustrates in another way the influence of gravi-
tation on root formation. The reader will notice that in the
>
t
*
in 1 7]
WEB— BR YOPHYLL UM
47
stem
node. This occurs only after a long time and
side of a stem.
from
The experiment demonstrates, therefore, that roots will form
on the concave side of a passively bent stem of Bryophyllutn caly-
cinum if this side is the under side of such a stem.
viii. Theoretical remarks and summary
theoretical remarks may be brief. We believe
ts show first that in Bryophyllum calycinun,
a
Fig. 29
stances which induce root formation
have a tendency to collect on the lower
side of a horizontally placed stem,
although roots may appear also in
nodes on the upper side (especially at
the basal nodes), under special condi-
tions which will be discussed in another
paper
this
a horizontally suspended stem of Bryophyllum will become concave
on the upper side, and that this curvature, which will give such a
piece a U-shape, is due to a longitudinal growth of the cortex on
the under side of the horizontally suspended stem.
2. We have seen that a leafless stem bends much more slowly
than a stem in which one or more leaves are preserved; and we find
4 8
BOTAXICAL GAZETTE
[JANUARY
also that the roots form more slowly in a leafless stem than in a
stem with leaves. We find also that in a general way the
>
v
w
*&r*.
^^^m
Fig. 30
amount of curvature and the amount of root formation vary in
the same sense.
i9 1 7l LOEB—BR YOPH YLL UM
49
3. Both phenomena
formation
the stem.
>phyll
preserved
very
localized
from
curvature
of a U with the concave side above. In such stems an extensive
and rapid root formation will take place first in the second and
fourth nodes behind the leaf on the lower side and also in the most
basal nodes. The second and fourth nodes behind the leaf are
kinds
curvature
of the growth of roots. It should be pointed out also that in
Byrophyllum the axes of successive nodes are always at right angles
to each other, so that the favored nodes, the second and fourth
behind the most apical one, all have the same orientation. It is
structural
curvature center around
behind
otherwise leafless stem.
4. If in a horizontally suspended stem only one leaf is left at the
base of the stem (and on the lower side) the curvature is usually
considerably less than in a stem with a leaf in the apex. The
curvature in a stem with a basal leaf is confined to the region behind
or around the leaf. It harmonizes with our previous statements
that in such stems little or no root formation takes place, and that
the root formation which occurs is confined to the node opposite
the basal leaf and to the basal cut surface. When the piece of
internode left behind the basal leaf is long, a more extensive curva-
ture may occur than when the piece of internode left is short.
5. This difference in the influence of the apical and basal leaf
can be made more striking when either the flow of substances in the
stem is retarded (for example, by incisions in the stem) or when
the resistance to the bending is made greater (by removing the
cortex on the upper side of a horizontally placed stem whereby the
5°
BOTANICAL GAZETTE
[JANUARY
latter becomes concave on the lower side). In such cases geo-
tropic curvature becomes possible only in stems with a leaf at the
apex, but not in stems with a leaf at the base.
6. All these experiments become intelligible on the assumption
that each leaf has a tendency to send shoot-forming substances
toward the apex and root-forming substances toward the base of
*
the stem. If it could be proved that in Bryophyllum calycinum
a specific substance (hormone) is responsible for the geotropic
growth (in the cortex of the lower side of a horizontally suspended
stem), we might say that both substances show a tendency to
collect on the lower side of a horizontally placed stem, and that the
flow of both is influenced in the same way by the leaf. The apical
leaf sends both substances toward the base of a stem, while the
basal leaf acts as if it had a suction effect upon geotropic substances
contained in the apical region. Such an idea su
the fact that a leafless stem has the center of its geotropic curvature
in the middle (fig. 15), while a stem with a leaf at the base has
either no curvature (fig. 16) or has it only in the region of the leaf
While in Bryophyllum the hypothetical geotropic hormone is
from
forming hormone
m
be asso-
would
plants the hypothetical geotropic substance
ciated with the shoot-forming hormone. This
fact that in certain fir trees a horizontal branch next to the apex
may suddenly become negatively geotropic when the apex is cut
off. After the decanitation the
he decapitation the (hypothetical) geotropic substance
e was flowing to the apex now can flow into the hori-
:hes next to the apex, and the one which by chance
more of the substance than the others will be the first
to become vertical.
;he mechanical advantage due to
continued flow of these substances
becomes
Rockefeller Institute for Medical Research
New York City
1
PROTHALLIA AND SPORELINGS OF THREE NEW
ZEALAND SPECIES OF LYCOPODIUM
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 222
Charles J. Chamberlain
(with PLATES II-IIl)
Few botanists have even seen the prothallia of Lycopodium, and
most of those who have had such a privilege are indebted to one
man, Bruchmann of Gotha; fewer still have made any investiga-
tion of the subject. The reason prothallia and sporelings of
Lycopodium have not been so extensively studied as those of the
ferns is not lack of interest, but difficulty in germinating the spores
or finding prothallia growing naturally. In 191 1 I collected adult
plants of several New Zealand species of Lycopodium and made
some effort to find prothallia, but my time was too limited for
such slow, uncertain work. However, Professor A. P. W. Thomas,
at that time botanist of the University at Auckland, very kindly
gave me prothallia and sporelings of 3 characteristic New Zealand
species, Lycopodium laterale, L. volubile, and L. scariosum. Pro-
thallia and sporelings are known in so few species that it seems worth
while to give some account of this material.
Since the literature of the subject was examined with consider-
able care, all of the original papers cited being available, and since
E. A. Spessarb, a student of mine, is announcing in this issue of the
Botanical Gazette the first discovery of the prothallia and spore-
lings of several American species of Lycopodium, a historical resume
may be of service to those who are in favorable localities and who
might wish to study the subject.
Historical
Treub (7) introduced his classic account of the prothallium of
Lycopodium cernuum with the remark that the history of the subject
could be given in a few words, since it was necessary to cite only
3 or 4 investigators. Spring (2), Hofmeister (3), DeBary (4),
Fankhouser (5), and Beck (6) are mentioned ; but neither Spring
5 1 ] {Botanical Gazette, vol. 63
52 BOTANICAL GAZETTE [january
nor Hoemeister ever saw any prothallia. DeBary, and later
Beck, germinated the spores of L. inundatum, and Fankhouser
found a few prothallia of L. annotinum.
Treub overlooked the English surgeon, John Lindsay (i), who
nearly ioo years before had germinated the spores of the very species
with which Treub was dealing. Lindsay was also the first to
raise ferns from the spores. Having noted very young ferns grow-
ing in the open in Jamaica, he sowed the spores (" farina") and
watched their development. It was in connection with this work
that he tried L. cernuum. His own account is interesting: "I
have very lately sown that fine farina or dust contained in the
anthers of a species of the genus Bryum y namely, Bryum caespiti-
tium y or one very like it, and also the farina of Lycopodium cernuum.
-
There is a vegetable growth taking place where they were sown
which I hope will prove to be their young plants." Later, in a
letter to Sir Joseph Banks in regard to Bryum caespititium and
Lycopodium cernuum, he states that he had repeatedy sown them
both, and in proper situation found that they grew very readily.
There were no further figures or descriptions of either the Bryum
or Lycopodium.
Spring's failure to germinate spores brought him to the curious
conclusion that Lycopodium, and also Psilotum and Tmesipteris,
*
consist exclusively of male plants, the females having been destroyed
in some geological catastrophe. At this time it was generally
believed that the spores, if they should germinate, would develop
directly into the leafy plants. A few years later, Hofmeister
opposed this view and predicted that the spores would give rise to
prothallia bearing antheridia and archegonia, and that the leafy
plant would arise from the fertilized egg; but all attempts to prove
his theory by germinating the spores resulted in failure.
DeBary succeeded in germinating the spores of L. inundatum,
and in 9 days obtained prothallia consisting of 7 cells; but repeated
*
attempts failed to produce more advanced stages, except that one
prothallium was observed which had reached the 1 i-cell stage. The
prothallia soon died.
In 1873, Fankhouser, in Switzerland, found prothallia and
sporelings of L. annotinum growing naturally. This fortunate find,
1917] CHAMBERLAIN— LYCOPODIUM 53
i together with the results of DeBary, who had described early
stages of L. inundatum from cultures, made it possible to make a
general outline of the development from the germination of the
spore up to the adult pro thallium with sporelings attached.
i Beck sowed the spores of various species under various condi-
tions, but L. inundatum was the only one to germinate and the pro-
thallia did not get beyond the 10-cell stage. He asserted that
after 2 years the spores of L. clavatum showed chlorophyll and
looked as if they were about to germinate, but no cell division
occurred.
Fankhouser's DaDer aDDeared, i men have made
contributions to our knowledge of these peculiar prothallia. In
Treu
Javanese species. In
1885, Bruchmann (8) began his patient and persistent researches
upon the difficult temperate species with subterranean prothallia
which had baffled all previous investigators; and in 1887, Goebel
(10) found prothallia of L. inundatum, so that, with the stages
secured by DeBary, he was able to give a connected account of
this species.
Treub began his series with an investigation of L. cernuum.
He germinated the spores of this familiar tropical species and some
of the prothallia reached the early antheridium stage before the}
died. However, he found abundant material growing wild, and
so had a complete series from the germination of the spore to the
adult prothallium with embryos and older sporelings.
The prothallia are green and grow on the surface of the sub-
stratum, the largest reaching a height of 2 mm. When the spore
germinates, a more or less spherical body is formed, about 8 or 10
cells in diameter.
which Treub
the "primary tubercle," an alga-like filament then develops, at
divid
cylindrical body is formed more
primary
The
tip of the cylindrical portion is profusely branched, and at the base
and
The
embryogeny is particularly interesting, since the fertilized egg does
54 BOTANICAL GAZETTE [January
v>
not develop directly into a leafy plant, but produces a protocorm
with protophylls, resembling a miniature Phylloglossum.
Treub (9) next dealt with L. Phlegmaria, another familiar tropi-
cal species, epiphytic upon trees. The prothallia are found on the
tree trunks just below the surface of the humus, but they have no
chlorophyll, being entirely saprophytic and abundantly supplied
with an endophytic fungus. The main body is tuberous, about
2 mm. in diameter, more or less spherical or somewhat elongated,
and has several branches extending in various directions. The
*
branches vary from 1 to 6 mm. in length and bear antheridia or
archegonia or reproductive bodies which Treub called "propagula.
The antheridia and archegonia are usually at the tips of the
branches, not at the base as in L. cernuum. The propagula are
of two general types, one consisting of scores or even hundreds of
cells forming a flask-shaped body with a slender stalk of one or two
cells; the other is much smaller, more or less spherical in shape,
and consists of only a few cells, usually not more than 2 or 3, with
the outer walls very much thickened. In the first type the propag-
ula break off at the stalk and grow directly into new prothallia,
while in the second type there is a more or less prolonged resting
period. The first type seems to correspond to the gemmae of
liverworts and mosses, and the second type seems to correspond
to the brown bulbils of mosses.
Treub was not able to germinate the spores, and he believed
that most of the prothallia found in nature come from propagula,
prothallia from spores being comparatively rare.
The accounts of the development of antheridia, archegonia,
and embryo are very complete, but the vascular anatomy of the
sporeling is not described.
endo
fungus, and are the only <
from the spore to the adult
gonia
simple filament
days the prothallia developed to the primary
SH rested for several months, and finally resumed
completed the life history. As in L. cernuum, a
lindrical bodv several cells in thickness
i9i 7l CHAMBERLAIN— LYCOPODIUM 55
ments then develop and behave in the same manner, so that there
are several branches. The antheridia and archegonia are formed
at the tops of these branches, there being no leaflike organs as in
L. cernuum and L. inundatum.
The prothallia of L. carinatum, L. Hippuris, and L. nummularis
forme are all of the L. Phlegmaria type, those of L. carinatum bearing
such a close resemblance that Treub (ii) warns prospective col-
lectors against collecting in localities where both species occur,
since it is impossible to distinguish either the prothallia or the
embryos. The prothallia of L. Hippuris are similar, but are more
vigorous and the branches are thicker. Treub was not able to
disentangle complete prothallia of L. nummular ij or me from the
substratum and so had to write his account from fragments. He
did not find any endophytic fungus.
The final paper in Treub 's (12) series dealt with the embryo of
L. cernuum. The series of stages was very complete, from embryos
consisting of a few cells, through the protocorm stages, and up to
sporelings with a few leaves. After the embryo has developed a
protocorm with protophylls resembling a small Phylloglossum, a
definite growing point is organized which develops into a leafy
axis and at the same time the first root appears. Treub indicated
the course of the vascular bundles, but did not make any further
study of the anatomy. He regarded the protocorm as a recapitula-
tion of a Phylloglossum stage in the ancestry of Lycopodium.
In 1884, the same year that Treub (7) began his research upon
tropical forms, Bruchmann (8) found 3 prothallia of L. annotinum y
and thus began a series of researches which extended over 25 years
and resulted in clearing up the life-histories of the much more
difficult temperate species. Bruchmann's first paper appeared in
1885, but Treub's first account, although dated 1884, appeared
at about the same time, so that neither knew the other was working
upon prothallia. Bruchmann's (13) most extensive work, which
gained him the prize of the Paris Academy of Science, appeared in
1898, and contained descriptions of L. clavatum } L. annotinum, L.
complanatum, and L. Selago. All were found growing in the Thur-
inger forest near Gotha, but the germination of the spores and
earliest stages in the development were lacking. The development
56 BOTANICAL GAZETTE [january
of antheridia, archegonia, and embryos are very clearly described.
Ten years later this account was supplemented by a very complete
description of L. complanatum. Although Bruchmann (15) had
made repeated efforts to germinate the spores of various species, he
met only the failures which had discouraged other botanists; but
finally his perseverance was rewarded and he was able to give a
complete account of the germination and early development of
L. clavatum, L. annotinurn, and L. Selago. The surprising feature
is the long-delayed germination. The spores of L. Selago germi-
nated in 3-5 years, and the development of antheridia and arche-
gonia was complete in 6-8 years; L. clavatum and L. annotinurn
were even slower, germinating in 6-7 years and requiring 12-15
years to complete the development of antheridia and archegonia.
Bruchmann suggests that possibly the periods might be shortened
artificially if the proper stimuli could be discovered. All the species
reported in Bruchmann's various papers are subterranean and
saprophytic, but the spores germinate independently and develop
to the 4 or 5-cell stage, and at this stage the fungus must enter or
there will be no further development.
L. salakense, which Treub (ii) succeeded in keeping in cultures
throughout the whole life history, is green, aerial, has no fungus,
and germination takes place in a few days. L. cemuum is also
aerial and green and germinates with equal promptness, but it does
not develop beyond the primary tubercle stages unless the fungus
enters. L. inundatum in DeBary's cultures developed to an early
primary tubercle stage with some chlorophyll and then died. The
subsequent work of Goebel (10), who found prothallia growing
naturally, proved that this species also has an aerial, green prothal-
lium with an endophytic fungus. In L. cemuum and L. inundatum ,
however, the fungus infection is much slighter than in the sapro-
phytic species.
So far as I have been able to determine, there is only one paper
which makes any mention of the prothallia of New Zealand species
of Ly co podium, and this paper by Hollo way (16) deals primarily
with the anatomy of the sporophyte. The investigation, both in
the field and in the laboratory, is of such high grade that we hope
Holloway will sometime give us an extended account of the pro-
>
1917J CHAMBERLAIN— LYCOPODIUM 57
thallium and the anatomy of the sporeling. The varied species,
ranging from epiphytes to ground forms, with prothallia ranging
from the green, leafy aerial type to the deepest subterranean
tuberous type, make New Zealand an ideal nlace for such a studv.
Material and observations
in
disposal. Lycopodium later ale has a stout creeping rhizome, with
numerous erect branches, and cones borne laterally; L. scariosum
has a somewhat similar habit, except that the cones are terminal;
L. volubile is the most beautiful species of the genus, bearing a
striking resemblance to Selaginella as it trails along the ground
or over bushes; but, unlike Selaginella, it keeps well after being
gathered and is much used for table decoration.
PROTHALLIA
L. laterale. — The only reference I have been able to find in
regard to the prothallium of this species is in Holloway's (16)
paper. He says "in the case of L. laterale prothallial plants were
found in two localities, growing on recently overturned marshy
soil. The prothallus of this species corresponds to the type of
L. cernuum, is small and short-lived, and is situated at the surface
of the ground."
I had at my disposal 3 prothallia w T ith protocorms attached and
one older protocorm entirely free from the prothallium. In the
first 3, each of the protocorms bore 2 fully grown protophylls; the
older protocorm bore 10 protophylls. Two of the prothallia with
their young plants are shown in figs. 1 and 2, the exact size being
indicated in fig. ia. The older protocorm with its 10 protophylls
is shown in fig. 3. In fig. 1 the particles of sand and soil are not
represented.
The upper half of the prothallium projects above the surface
of the soil. There is a more or less spreading crown of leafy lobes,
abundantly supplied with chlorophyll, and at the base of the inner
face of these lobes the antheridia and archegonia are borne. It
seems evident that the base of the prothallium was first to develop,
but no sharply differentiated primary tubercle, like that shown in
58 BOTANICAL GAZETTE [january
Treub's figures of L. cernuum, was found in these specimens.
However, the base of the prothallium is more pointed than in
L. cernuum, and this pointed base may represent the primary
tubercle.
In proportion to the size of the prothallium, the protocorm is
much more massive than in L. cernuum. There is no single,
definitely organized growing point giving rise to all the protophylls,
but rather a series of points, each giving rise to a protophyll.
Stoma ta are abundant almost to the base of the protophyll; they
are of the simplest type and open into a loose parenchyma with
large air spaces. The transverse section is circular and shows a
single weak vascular strand extending a short distance into the
protocorm and ending blindly, without uniting with the strands
of neighboring protophylls. The protuberance shown in front of
the large protophyll in fig. 2 might be mistaken for the growing
point from which the leafy axis is to be developed, but that point
is formed much later, after several protophylls have appeared.
The prothallium and protocorm shown in fig. 2 are similar, but indi-
cate that there is considerable variation in both structures. Out-
lined against the protocorm is a second embryo.
The much older protocorm (fig. 3) indicates that the protophylls
arise at irregular points, although there is a general progression,
so that the protocorm resembles a very short horizontal rhizome.
The 2 protophylls in the foreground are evidently the first ones
formed, and the 3 much smaller ones at the left are the latest. The
leafy axis of the permanent plant has not yet appeared. This
specimen and also those shown in figs. 1 and 2 were sectioned, but
the soil prevented satisfactory results. However, the sections
showed the position of sex organs, the distribution of the fungus,
and the relation of the protocorm to the prothallium. These
features are shown, in a very diagrammatic way, in fig. ib.
L. later ale belongs definitely to the type represented by L.
cernuum and L. inundatum, since it has a short-lived green prothal-
lium and an ephemeral protocorm with protophylls preceding the
permanent leafy plant. L. salakense also belongs here, since the
prothallium is green, and in its earlier stages behaves like that of
L. cernuum; but it differs from the other 3 in having no endophytic
I.
1917] CHAMBERLAIN— LYCOPODIUM 59
y fungus. Whether it has a protocorm stage is not known. Treub
j failed to find sporelings when he made his first investigation; later,
in his work on the embryogeny of L. cernuum, he figures a proto-
corm stage in L. salakense.
It is interesting to note that the protocorm stage has been found
only in L. cernuum, L. salakense, L. inundatum, and L. later ale, all
of which have spores which germinate, giving rise to green short-
lived prothallia. The spore-bearing plants of all 3 species, as well
as that of L. salakense, grow upon the ground. No green prothal-
lium or a protocorm phase in the embryogeny has yet been
reported for any epiphytic Lyco podium.
L. volubile. — The only reference to the prothallium of this
species is by Holloway (16). He says "the prothallus is large,
firm, and long-lived. Healthy prothalli were seen still attached to
sporelings which were as much as 10 cm. in length. Generally the
prothalli are subterranean, being buried 1-4 cm. in depth; in several
instances, however, they were observed growing on the surface of
the ground, and the upper portion of the prothallus was then well
supplied with chlorophyll."
The material at my disposal included 9 prothallia and 2 spore-
lings, one of them still attached to the prothallium (figs. 4-9). All
belong to the subterranean tuberous type, and 4 of them (figs. 4,
5, 8, and 9) show a primary tubercle. Although the material is
somewhat limited, it is evident that there is considerable variation
in size and form.
The endophytic fungus is most abundant midway between the
center and the surface, and is entirely lacking in the crown, in the
upper part of the depression within the crown, and in the axis of
the prothallium. Cells with considerable fungus abut directly
upon those with none at all, making a sharp contrast (fig 12). A
detail is shown in fig. 13.
The crown is differentiated into two regions in some places, only
the inner one of which bears archegonia and antheridia, as shown
in figs. 5 and 6 ; but even in these 2 prothallia some portions of the
crown show no such differentiation, and the prothallia shown in
figs. 7 and 8 have uniformly rounded crowns with no indication of
two regions. While most of the sex organs are on the swollen rim
6o ' BOTANICAL GAZETTE [jaxuary
of the crown, they are not confined to this region, but occur in
scattered patches within the rim on any part of the depressed region.
A sectional view of a typical distribution of archegonia, antheridia,
and the fungus region is shown in fig. 14.
The antheridia vary in size, shape, and output of sperms. They
form hemispherical projections, with a nearly spherical mass of
sperms; or they project scarcely at all, in which case the mass of
sperms is not quite so regular. In a few cases, the sperm mass was
elongated, making the topography bear some resemblance to that
of an archegonium. In all cases, only one layer of cells separates
the sperms from the surface, so that the essential course of develop-
ment is uniform. A typical view is shown in fig. 15.
The foot of the sporophyte is strongly haustorial, and the cells
surrounding it have some starch but very little protoplasm or other
visible contents; consequently, the food supply must come largely
from the fungus region and must be in a liquid condition even at
a considerable distance from the foot. This is quite different from
the condition in some gymnosperms, where only a single layer of
cells may separate the haustorial cells of the embryo from those
containing an abundance of food material in solid form. The foot
is small and the vascular strand does not extend into it, but extends
in an unbroken line from the shoot into the root, which is very late
in developing. However, a few elongated cells, which do not
become lignified, bend away from the main axis and point toward
the foot.
L. scariosum. — The only description of this species is that given
by Holloway (16), who says "the prothallus of L. scariosum was
discovered in two localities. Like that of L. volubile, it appears
to correspond to the L. clavatum type. It is large, firm, and long-
lived, and in every case was found deeply buried (2-6 cm.)." Three
specimens of this species were available and all had reached matur-
ity, one bearing a young plant 18 mm. long, and the other two
showing the foot and base of younger sporophytes which had broken
off. Both prothallium and sporeling are larger and coarser than
in L. volnbile, as can be seen by comparing figs. 9 and n, which are
drawn to the same scale. The prothallium is densely infested by the
fungus, which has about the same distribution as in L. volubile.
1917] CHAMBERLAIN— LYCOPODIUM 61
. . Origin of the subterranean habit. — That the green leafy
prothallia represent the original type from which the subterranean
forms have diverged can scarcely be doubted. The species with
green, leafy prothallia (L. cernuum, L. inundatum, L. salakcnse,
and L. later ale) have spores which, in the first 3 species, are known
1 to germinate immediately; while in all those with subterranean
prothallia the spores germinate only after a long resting period.
It would seem that some change has occurred in the spore which
has delayed the germination; and then only such spores as reached
*
a protected situation would survive to germinate at all. Germinat-
ing in protected situations, with little or no light, the prothallia
naturally would assume the forms of subterranean, dependent
structures. That this has been the order of regression is indicated
I by the fact that the leafy crown has not been lost altogether, but
I only modified. In L. annotinum, as described by Bruchmann, the
I prothallium is subterranean and saprophytic, but still retains some
I of the leafy appearance ; in L. later ale the crown is sometimes broken
[ up into separate fleshy cushions which may represent leafy lobes ; in
more extreme cases, there is merely a swollen, fleshy rim to repre-
sent the leafy structure. The position of antheridia and archegonia
is about the same as in the green, leafy forms.
If those who are expert in hastening the germination of seeds
which normally have a long resting period, could find some way to
make the spores of L. annotinum, or some such species, germinate
immediately, it would not be surprising if green, leafy prothallia
should appear.
anatomy of the sporophyte
structure of the adult sporophvte Lycopodi
still presents some difficult problems, although investigations like
those of Hill and others have cleared up some of the phases. How-
ever, it seems likely that the final solution will come through a
comparative study of sporelings, intermediate stages, and adult
plants. Treub (7), Bruchmann (13), Miss Wigglesworth i
and Holloway (16) have figured and described a few section-;
material has been scanty or other features of the problem have so
but
little attention.
portant feature
62
BOTANICAL GAZETTE
[JANUARY
It would be dangerous to draw any serious conclusions from a
study of 2 or 3 sporelings, all of which had reached the leafy stage;
but, in the present condition of the subject, it seems worth while
to describe a few features. The study was made from the sporelings
shown in figs. 9-1 1.
In L. volubile the foot is quite small, and although somewhat
larger in L. scariosum y no vascular strand extends into it, but a few
cells, not lignified, point in its direction. The vascular strand
extends in an unbroken line from the tip of the stem to the tip of
the root, which in both species is late in appearing.
The sporeling of L. volubile shown in fig. 9, and that of L.
scariosum shown in fig. 10, were sectioned transversely down to
the crown of the prothallium, and the portion below the crown was
then cut longitudinally. It would have been much better if trans-
verse sections had been continued throughout. In both species
the leaves are surprisingly like the protophylls of L. later ale.
Throughout a considerable portion of their length the transverse
section is circular, and even in the broader middle region the leaves
are thick and spongy, consisting almost entirely of very loose
parenchyma with large intercellular spaces and a single vascular
strand. Stoma ta are irregularly scattered over the entire surface
(fig. 16). The adult leaves in both species are rather thin.
In L. scariosum the shifting topography of the stele is a conspicu-
ous feature, especially in the upper, leafy region ; in the lower half
of the sporeling, where there are only a few scale leaves with no
leaf traces, the arrangement is more uniform. Near the middle of
the leafy portion, a hexarch, pentarch, and tetrarch condition occurs
within a vertical distance of 1 mm. Throughout the lower one-
third of this specimen the stele is rather constantly tetrarch; but,
just above the foot a few sections show a triarch and even a diarch
stele. That the leaf traces connect with the protoxylem points
is evident at a glance; but whether the leaf traces determine the
topography is not so clear. However, it is significant that the
stele is more complex in the leafy region and that it attains its
greatest complexity in mature plants with larger leaves and vigorous
leaf traces. In various places there are indications of the banded
arrangement characteristic of the adult stele.
19 1 7] CHA MBERLAIN—L YCOPODIUM 63
)
The differentiation of the vascular tissues is interesting. A
short distance below the meristem the large cells which are to form
the largest tracheids are easily recognized, and some of the
cells of the points of the radial structure can be distinguished,
although lignification has not yet begun. Very soon the points
of the radial structure begin to lignify and are then marked off
very sharply from the surrounding tissues (fig. 17). These patches
of lignified tissue consist almost exclusively of coarsely pitted
tracheids. It is possible that there are some spiral vessels, but it
looks as if practically all of the spirally marked cells belong to the
leaf traces. If protoxylem is to be identified by spiral and annular
markings, very little of the tissue which becomes lignified at this
early stage would satisfy such a criterion; but the tissue is so
well defined and becomes lignified so far in advance of the rest of
the xylem, and is so sharply marked off from the large cells which
in longitudinal view have the typical scalariform marking, that it
may very properly be called the protoxylem. It should be recalled
that in the cycads spiral vessels in the protoxylem are largely
'confined to the seedling, the protoxylem of the adult plant consisting
almost exclusively of tracheids.
The study of the root was not satisfactory. Near the tip the
bundle is C-shaped and diarch with the phloem in the sinus.
The sporeling of L. volubile is comparatively slender and in
every way more delicate than that of L. scar io sum. In the upper
leafy portion the stele is quite regularly radial and tetrarch; but
from the secondary root (r in fig. 9) down to the pro thallium the
structure is regularly or irregularly triarch. In connection with the
more uniform topography of this stele, it should be noted that the
leaves and their single vascular strand are not nearly so robust
as in L. scariosum. The adult stele has the banded arrangement.
The differentiation of the tissues of the stele proceeds as described
for L.
scariosum.
Summary
1. Lyco podium laterals has a green, leafy prothallium, and there
is a protocorm-protophyll stage in the embryogeny. L. volubile
and L. scariosum have subterranean prothailia with no protocorm
stage, but the early leaves have the structure of protophylls.
64 BOTANICAL GAZETTE [january
2. In L. scariosum and L. volubile the sporeling has a radial
stele. The adult plants have a banded stele.
3. The outer part of the ray of the radial structure consists
almost exclusively of pitted tracheids with scarcely any spiral
vessels, but becomes lignified long in advance of the large tracheids
of the metaxylem, and should be regarded as the protoxylem.
University of Chicago
LITERATURE CITED
i. Lindsay, John, Account of the germination and raising of ferns from the
seed- Trans. Linn. Soc. 2:93-100. pi. 18. 1794.
2» Spring, A. F., Monographie de la famille des Lycopodiacees. 1842.
3. Hofmeister, W., Vergleichende Untersuchungen hoherer Kryptogamen.
1851.
4. DeBary, A., Sur la germination des Lycopodees. Ann. Sci. Nat. Bot.
IV. 9:30-36. pi. 4. 1858 (published almost simultaneously in other
places).
5. Fankhouser, L., t)ber den Vorkeim von Lycopodium. Bot. Zeit. 31: 1-6.
pi. r. 1873-
6. Beck, G., Einige Bemerkungen iiber den Vorkeim von Lycopodium.
Oesterreich. Bot. Zeit. 30:341-344. 1880.
7. Treub, M., Etudes sur les Lycopodiacees. I. Le prothalle du Lycopo-
dium cernuum L. Ann. Jard. Buitenzorg 4:107-138. pis. 9-17. 1884.
8. Bruchmann, H., Das Prothallium von Lycopodium. Bot. Centralbl.
21:23-28, 3°9~3 I 3- P 1 ' T - l88 5<
9. Treub, M., Etudes sur les Lycopodiacees. II. Le prothalle du Lycopo-
dium Phlegmaria L. Ann. Jard. Buitenzorg 5:87-114. pis. 11-22. 1886;
III. Le developpement de Pembryo chez L. Phlegmaria. 5:115-139*
pis. 23-31. 1886.
io* Goebel, K., Uber Prothallien und Keimpflanzen von Lycopodium inun-
datum. Bot. Zeit. 45:161-168. pi. 2. 1887.
11. Treub, M., Etudes sur les Lycopodiacees. IV. Le prothalle du Lycopo-
dium salakense. Ann. Jard. Buitenzorg 7:141-146. pis. 16-18. 1888;
V. Les prothalles des Lycopodium carinatum, nummular if or me y et Hip-
puris. ibid., 146-150. pi. 19.
12. , Etudes sur les Lycopodiacees. VI. L'embryon et la plantule du
Lycopodium cernuum L. Ann. Jard. Buitenzorg 8:1-14. pis. 1-5- 1890;
VII. Les tubercles radicaux du Lycopodium cernuum L. ibid. i5~" 22 '
pis. 6-12; VIII. Considerations theoretiques. ibid. 23-37.
13* Bruchmann, H., tJber die Prothallien und die Keimpflanzen mehrerer
Europaischer Lycopodien. pp. 119. pis. 1-8. 1898.
BOTANICAL GAZETTE, LXIII
PLATE II
\
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f
I
4
6
•••/
r
k
p
CHAMBERLAIN on LYCOPODIUM
BOTANICAL GAZETTE, LXIII
PLATE III
ir-V
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k:7-
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!-'.'-■
v. # l*-W
i I I
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.
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■
.-,
■
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.
14
13
17
CHAMBERLAIN on LYCOPODIUM
1917] CHAMBERLAIN— LYCOPODIUM 65
com-
14. Wigglesworth, Grace, The young sporophytes of Lycopodium
planatum and L. clavatum. Ann. Botany 21:211-234. pi. 22. 1907.
15. Bruchmann, H., Die Keimung der Sporen und die Entwickelung der
Prothallien von Lycopodium clavatum^ L. annotinum, und L. Selago.
Flora 101:220-267. figs. 35. 1910.
16. Holloway, J. E., A comparative study of the anatomy of six New Zealand
species of Lycopodium. Trans. New Zealand Inst. 42:356-370. pis.
31-34- 1910-
EXPLANATION OF PLATES II-III
Fig. 1. — Lycopodium later ale: prothallium with leafy crown at left and
bearing, at right, a protocorm with 2 fully grown protophylls and one young
protophyll; X 20 (fig. 1a shows this plant natural size; fig. ib is sectional view).
Fig. 2. — L. later ale: prothallium, at right, bearing a protocorm with 2
protophylls and also a second embryo; the soil and sand have not been re-
moved; X20.
Fig. 3. — L. later ale: protocorm with 10 protophylls; X6.
Fig. 4. — L. volubile: prothallium showing primary tubercle at base; the
crown is very even; X 10.
Fig. 5. — L. volubile: prothallium showing crown with numerous arche-
gonia and antheridia; primary tubercle at base; Xio.
Fig. 6. — L. volubile: prothallium with archegonia and antheridia; the
crown is lobed ; Xio.
Fig. 7. — L. volubile: large, irregular prothallium; Xio.
Fig. 8. — L. volubile: prothallium with 2 young sporophytes; Xio.
Fig. 9. — L. volubile: prothallium with sporeling; a secondary root is
shown at r; X4.
Fig. 10. — L. scariosum: prothallium with sporeling; X4.
Fig. 11. — L. scariosum: lower part of a young sporeling showing roots
and foot; X4.
Fig. 12. — L. volubile: diagrammatic view of prothallium with foot and
lower part of sporeling.
Fig. 13. — L. volubile: detail of prothallium.
Fig. 14. — L. volubile: diagrammatic sectional view of prothallium showing
archegonia, antheridia, and distribution of fungus, the latter indicated by
shading.
Fig. 15. — L. volubile: portion of prothallium showing antheridia.
Fig. 16. — L. volubile: transverse section of leaf.
Fig. 17. — L. scariosum: transverse section of stem of sporeling before the
large tracheids become lignified; px, protoxylem; p, phloem.
Fig. 18. — L. scariosum: same sporeling lower down; large tracheids have
become lignified.
Fig. 19. — L. scariosum: same sporeling showing indication of banded
arrangement.
*
PROTHALLIA OF LYCOPODIUM IN AMERICA
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 223
Earle Augustus Spessard
(with twenty-one figures)
Since Bruchmann's great work upon the prothallia of the
European species of Lyco podium appeared in 1898, and probably
before that date, numerous attempts have been made to find
prothallia in America; but, so far as the writer has been able to
■
determine, no successful searches have been reported. |
While taking a correspondence course in botany with Professor
Charles J. Chamberlain, he suggested that I avail myself of
the opportunities afforded by my location in a Lycopodium region
and make a thorough search for prothallia. In accordance with
his suggestions and directions, the work was undertaken and has
resulted in the finding of 21 prothallia and over 50 sporelings,
representing 5 species: L. clavatum, L. complanatum, L. annotinum,
L. obscurum, and L. lucidulum. It is also a pleasure to acknowledge
my indebtedness to Dr. W. J. G. Land for valuable suggestions.
The first specimen, that of L. complanatum , was found May 22,
19 16. During the same month and in September of the same
year, 6 more of this species, 8 of L. clavatum, 3 of L. obscurum, 2 of
Z,. annotinum j and 1 of L. lucidulum were dug up, making 21 in >
all. Although the first sporeling bearing a foot, which indicated
that a pro thallium was recently present, was found on April 10,
1915, it was not until May 20, 1916, that a second was found 10
miles from it. During this interval approximately 150 days were
spent crawling over the ground, among and around the dense beds
of adult sporophytes.
At first these tedious and futile efforts would seem to indicate
that prothallia are rare. Yet, when it is noted that 17 of the 21
specimens were obtained from an area not more than 10 m. square,
only about one-fourth of which was actually dug up; and further-
more, that as many as 6 were yielded by one small space 4 cm.
Botanical Gazette, vol. 63]
[66
1917] SPESSARD—PROTHALLIA OF LYCOPODIUM 67
square, it seems probable that prothallia are rather abundant.
The probability is even greater since the discoverer of these 21
prothallia was almost absolutely ignorant of the appearance of
Ly co podium prothallia.
The discovery of the original locality was almost an accident.
It is a place where one would least expect to find Lycopodium
prothallia, at least those of L. complanatum , L. clavatum, and
Z,. annotinum, since it is almost completely bare of adult sporo-
phytes of these 3 species. I was wandering about looking for
Morchella, when by chance I caught sight of an old sporeling of
L. clavatum, growing in an exposed position between some winter-
green plants. An examination of the soil showed no prothallium.
No adult sporophytes were within sight; but a sporeling is a good
sign, and this encouragement led me to make the final successful
search two days later.
Lying to the northwest of Marquette, Michigan, are a brewery
and the remains of an old pesthouse. To the east of this pest-
house, about 700 m., is an open space bordering an open pasture
on the north, a small wooded swamp on the east, and a wood com-
posed of second growth poplar and maple on the west. A path
runs to the northwest from the road which leads from Marquette
to the pesthouse. Beside this path, at the distance indicated
from the pesthouse, 18 of the 21 prothallia and most of the spore-
lings were found. The other prothallia and sporelings were found
in two separate stations, the one half a mile, the other two miles
from this one described.
The soil is mainly sand, covered in places by a very thin layer
of humus; that within the edge of the wood is a black sandy loam.
The specimens of L. annotinum and L. lucididum shown in figs. 9
and 10 are the only ones which were found in the sandy loam where
the ground is constantly shaded in summer. This specimen of
enorm
■hile
All the other
specimens and most of the 50 sporelings were found in open,
exposed, sandy places. The topography is uneven, rocks jutting
up here and there between water-logged regions. Scattered about
on the elevated regions are numerous small sandy knolls covered
68
BOTANICAL GAZETTE
[JANUARY
partly by Polytrichum, and sometimes by a species of grass. In
many spots these knolls are absolutely bare save for a few plants
of P olytrichum . It was in these knolls that all but 2 of the 21
prothallia were found, as well as most of the sporelings.
Figs. 1-8.
specimen
openings
form the lobes entirely, Xs; figs. 4, 5, prothallia of L. obscurum (?), crown is double,
XSJ figs. 6-8, prothallia of L. clavatum; in fig. 6 the antheridial lobes are marked as
in figs. 1 and 2; in fig. 7 the lobed edge is double; Xio.
The frequent occurrence of sporelings and prothallia on these
small, bare, exposed elevations suggests the idea that those spores
which fall in such localities are first of all beaten into the ground
*
1917] SPESSARD—PROTHALLIA OF LYCOPODIUM 69
by the frequent rains; later, they are covered over by the shifting
surface sand, and are finally conveyed to a favorable depth by the
percolating soil water. No experiments were made to see whether
this is the correct interpretation; but it was this idea which led
to investigate the knolls. This observation was heeded in all
me
and
more
So far as the elevation of the knolls is concerned, too much
mportance
The fact that they are
elevated somewhat and exposed as they are to the air currents
merely causes them to be covered by leaves less frequently than
wooded regions near them, and
more
ported thither. This idea is corroborated by the fact that many
sporelings of L. lucidulum and L. annotinum, as well as 3 prothallia,
were found in the middle of a trail which is frequently used by
hunters. In these instances the spores were clearly trampled into
the soil until they found the depth required for their growth into
prothallia. I suspect that future observations may show that the
prothallia of L. annotinum and L. lucidulum require more moisture
than the other species mentioned. The 3
ment
specimens I found of these 2 species, although the surface indica-
tions were similar, grew in decidedly wetter places.
In searching for prothallia, soil was removed with forceps.
This method was not very satisfactory, however, and 4 of the
prothallia were broken or pierced by the forceps before they were
seen. It would be better to remove the soil to a depth of 10 cm.
wash it through a coffee sieve. This would not only avoid
ianger of damaging Drothallia, but would increase the proba-
and
bility of finding young stages. The specimens grew at depths
the
varying between 1 and 7 cm. The species growing nearest
surface is L. lucidulum; the one growing deepest is L. obscurum.
In one hole 2 kinds, L. clavatum and L. obscurum, were seen within
2 cm. of each other.
The prothallia of L. clavatum and L. annotinum grow with the
wrinkled side toward the surface, and the primary tubercle pointed
downward; that of L. lucidulum grows erect and the sporeling
•
t
-
r«r
Figs 9-15.— Fig. 9, prothalhum bearing a sporeling of £. lucidulum, the only
specimen found, showing 4 paraphyses, archegonia, primary tubercle, rhizoids, and
an enlargement made by foot of sporeling, X6; fig. IO) prothalhum of L. annoknum
bearing 3 sporehngs, smallest one just emerging from upper tip of lower lobe of game-
tophyte, natural size; fig. n detailed drawing of largest sporeling shown in fig. 10,
X3; fig. 12, old sporeling of L. clavatum with foot still present, having lost erect habit
of younger sporehngs and assumed trailing habit of adult, X2; fig. 13, sporeling and
portion of gametophyte of L. obscurum, rest of gametophyte being like corresponding
portions ot ng. 5 , X4. 25; fig 14 diagram showing leaf contour of sporehngs of L. lu-
cidulum (I), L. annohnum (a), L. clavatum (c), and L. obscurum (0); fig. 15, diagram
showing general profile of leaves of sporehngs, the leaf being directed upward in
L. lucidulum (I) drooping m L. annotinum (a), directed upward but bearing bristle in
L. clavatum (c) bending downward then upward in L. obscurum (0), leaving the
stem almost at a right angle.
1917] SPESSARD—PROTHALLIA OF LYCOPODIUM 71
arises straight out of the end lying immediately beneath the
surface of the soil. The habit of growth cannot be stated defi-
nitely for L. obscurum and L. complanatum. The specimen of
L. complanatum shown in fig. 3 was found in the same position as
the specimen of L. obscurum shown in fig. 13. All the other
specimens of L. obscurum and L. complanatum which I collected
were disturbed before I saw them, and consequently their exact
position was not determined, except the one in fig. 1 which grew
vertically. In size, the prothallia of figs. 4 and 5, are very similar
to that of fig. 13. This resemblance in size, together with a common
external contour, are my only reasons for assuming that these 3
specimens belong to the same species. But here arises a difficulty.
mm m
mm
find the two growing in exactly the same position. This may
mean two things; either the prothallia I have classed with L. com-
planatum , except no. 1, might as readily belong to L. obscurum ,
or the prothallia of L. complanatum grow in various positions in
regard to the directions of their axes. If the axis of a prothallium
of L. complanatum can be shown to grow always in a vertical
position, and if that of L. obscurum can be shown to grow always
in a horizontal position, the identification of the two species will
then become a very simple matter if care be taken w r hile hunting
for them. I can only regret that this important point must be
left for future observation to settle. 1
Adult sporophytes of L. cfavatum and L. annotinum were rare
in this immediate locality, only one small patch of each having
been found. A few plants of L. complanatum were found. L.
obscurum and L. lucidulum grow in small clumps throughout the
region.
The 50 sporelings belong mainly to L. clavatum, but a few were
found of all the other species mentioned in this paper except
L. complanatum. Since the sporeling is the first guide in the
x On November 5, 19 16, after this paper had gone to press, the writer found a
large specimen of L. obscurum with sporeling attached. It was of the same color
and shape as and grew horizontally like the prothallium labeled L. complanatum in
fig. 3. This bears out the suggestion that all the prothallia classed with L. com-
planatum, except no. 1, very probably belong to L. obscurum.
72 BOTANICAL GAZETTE [January
search for prothallia as well as in their identification, I have given
2 diagrams in figs. 14 and 15 to show the specific differences between
the juvenile leaves of the 4 species of sporelings which I obtained.
If the descriptions of these 4 species as given in Gray's Manual
are followed carefully, the specific differences may readily be
determined. The leaves of L. clavatum terminate in a bristle
even in a stage as young as that sporeling of L. annotinum shown
in figs. 10 and 11. I have not been able to separate sporelings of
these 2 species at such a young stage or younger by any other
character than by the presence or absence of the terminal bristle
on the leaf. At such a stage the leaves have not yet assumed
such very definite directions of growth as they do a little later,
and as indicated in a and c of fig. 15. The sporeling of L. obscurum
is easily identified by the 6 rows of leaves which early assume the
characters peculiar to this species. Of course in the sporeling
stage the leaves are fewer and more spreading than in the adult,
so that a hurried examination would scarcely show the relationship
between the two. I actually thought I was digging for a pro thai-
Hum of L. annotinum while removing the soil from around the
sporeling shown in fig. 13, and it was not until all the sand had
been removed from among the rhizoids of the prothallium, and
after the leaves had been examined under a lens, that I discovered
my error. The sporeling of L. lucidulum cannot be confused in
any way with the sporelings of any of the species I have mentioned.
However, one may very readily believe that he is digging up a
genuine one only to find that peculiar winged bud at the bottom
of it. Yet, although I have experienced this disappointment a
hundred or more times, through it I have observed that the spore-
lings bearing a foot grow just a trifle deeper in the ground. Gener-
ally the bud lies nearly or wholly on the surface, and unless it is
rotted away, is readily seen. The sporeling of Z,. lucidulum looks
exactly like one of the plants which grows from a bud, except that
it has a distinct foot. Both bear leaves like an adult plant. Some
of the plants in the vicinity are Morchella, Polytrichum Acer,
Populus, Pteris, Gaultheria, Rhus, and Poly gala.
The largest specimen of L. annotinum (fig. 10) measured 10
X7 mm. It bore 3 sporophytes, one of which reached only 0.5
IQI71
SPESSARD—PROTHALLIA OF LYCOPODIUM
73
cm. above the ground, and another had just emerged
mm
In color it resembled closely the gametophyte of
Botrychium virginianum. The specimens of L. clavatum were
much smaller and almost white
6.5X5 mm. to 5X3 mm. Th
mm., and the smallest 2X1 mm
from
jment measured
and 8 show the <
specimens
fragments were more twisted and wrinkled than
Figs. 16, 17. — Fig. 16, antheridium of L. clavatum in sperm mother cell stage,
X365; fig. 17, archegonium of L. cotnplanatum immediately before neck canal cells
break down, the lowest neck canal cell being double, X365.
these, but both the fragments and the entire specimens showed a
distinct crown on the border, which in one case (fig. 7) was double,
the inner crown having an irregular outline. Each of the entire
prothallia showed the primary tubercle very distinctly, near the
middle, on the ventral side.
The prothallia of L. cotnplanatum were all entire except one
which had the lower portion broken off. Seven of these prothallia,
74 BOTANICAL GAZETTE [januaxy
illustrated by figs, i, 2, and 3, bore a single crown which was more
or less lobed. In section (fig. 19) these lobes proved to be masses of
antheridia. The crown on each of the 3 prothallia of L. obscurum
(figs. 4, 5) was double. An accident to the sections prevented a
study of the relation between the lobes and the location of the sex
organs in these prothallia. The crown was unequal in every
specimen of L. complanatum and L. obscurum , and the lobes
appeared only at one side, as shown in fig. 3.
The one prothallium of my collection which may cause some
readers to question is that of L. lucidulum. I have found 10
sporelings and only one prothallium, but this single prothallium
fortunately has a sporeling attached. This fact alone would not
serve to convince a botanist in doubt of its genuineness. However,
there are 5 reasons why I am convinced of its nature. Fig. 9
shows these 5 points. They are (1) archegonia, (2) paraphyses,
(3) rhizoids, (4) a primary tubercle, and (5) the sporeling arises
from it like the sporeling of any recognized gametophyte; there is a
foot, and a primary root originates at the point where the stem
breaks through. Certainly all these features cannot be connected
with a young plant of L. lucidulum of asexual origin or with an
associated fungus growth.
■
This prothallium of L. lucidulum, which, like that of L. obscurum,
I believe is new to botanists, shows some very interesting evolu-
tionary points. The body is somewhat cylindrical, but not entirely
so. It is somewhat more flattened longitudinally than the figure
shows. In this figure the flat side is turned toward the reader.
Near the middle it makes a short twist toward the left. In general
outline it looks like a prothallium of L. complanatum in the making,
but on the upper lobed region are 4 paraphyses. Such a feature
suggests a transition stage between the Phlegmaria type of prothal-
lium, as represented by L. Selago, and such a form as L. com-
planatum. The specimen contained no chlorophyll so far as I was
able to determine.
Among the 50 sporelings gathered there was a variation in age
between 1 and 5 years. Each season's growth above the soil
could be determined definitely by the alternate regions of longer
and shorter leaves on the species L. clavatum and L. annotinum.
3
r
1917]
SPESSARD—PROTHALLIA OF LY COP ODIUM
75
Fig. 11 shows in detail the largest sporeling of L. annotinum grow-
the prothallium represented in fig. 10. The sporeling of
from
serves
possible,
may obtain still bearin
It is very
figures of
^podium prothallia given in the various papers upon
mistake other forms
The sex organs may
identification
20
21
Figs. 18-21. Fig. 18, diagram of tissue regions in prothallium of L. clavatum
(antheridia and archegonia indicated) ; fig. 19, diagram of median region of prothallium
of L. complanatutn, the fungus-infected region being indicated in this and fig. 18 by
dotted shading; fig. 20, detailed sketch of fungus-infected region, showing its location
beneath the epidermal tissue, X75; fig. 21, single cell with endophytic fungus coiled
within (fungus passes freely from one cell to another by piercing the cell wall), X75°-
them is im
The number and variety
confusing.
appearances to small
ers which grow in the soil of a wood are be
Some of them are surprisingly similar in
complanatutn
of L.
I do not
threw away some genuine specimens
appeared to be tubers. I know t
even sectioned them in paraffine
prothallia.
and
7 6
BOTANICAL GAZETTE
[JANUARY
To establish definitely whether the forms that I have collected
are genuine prothallia of Lyco podium, therefore, I have drawn figs.
16, 17, 20, and 21 to show an antheridium, an archegonium in
which the lowest of the neck canal cells is double, and 2 detailed
sketches of the fungus-infected region. The diagrams in figs. 18
and 19 indicate the tissue regions shown by sections of 12 prothallia.
This article seeks to establish the fact that the prothallia of
Lyco podium have been found in America; to make known to those
botanists who may later desire to find prothallia for themselves,
what the conditions were under which the specimens collected
were found; and to announce the discovery of 2 new species of
Lycopodium prothallia, namely, L. obscurum and L. lucidulum.
Concerning the development and structure of the American
Lycopodium gametophytes, the writer hopes to deal in a later paper.
Marquette, Mich.
:
SIMILARITY IN THE EFFECTS OF POTASSIUM
CYANIDE AND OF ETHER
W. J. V. OSTERHOUT
(with one figure)
The writer has pointed out that typical anesthetics, such as
ether, chloroform, and alcohol, produce a temporary decrease in
permeability. 1 In view of the fact that anesthesia is looked upon
by some as a form of asphyxiation, it seems desirable to investigate
the manner in which permeability is affected by KCN, which not
only acts as an anesthetic, but also inhibits oxidation to a
remarkable degree.
The experiments here described were made in 191 2, in con-
nection with a series of experiments on anesthetics, of which a brief
announcement has already appeared. Since then a paper by
Krehan 2 has been published which states that KCN produces a
transitory increase of permeability which soon disappears. The
writer is unable to confirm this statement, as will appear from
the following account.
The experiments were made on tissues of Laminaria Agardhii.
The permeability was measured by determining the electrical resist-
ance in the manner described in previous publications. 3 The KCN
employed was Kahlbaum's best, and the distilled water was pre-
pared with especial care. A solution of KCN of the same con-
ductivity as the sea water (about o. 381M) was prepared. This was
added to the sea water and its effect on the tissues was observed.
The following experiment will serve to illustrate the procedure.
A lot of tissue which had in sea water a resistance of 1140 ohms
was placed in sea water to which had been added a solution of
KCN 0.181M in sufficient auantitv to make the concentration
1 Osterhout, W. J. V., The effect of anesthetics upo
N.S.37: 111-112. 1913.
*Internat. Zeit. f. Phys. Chem. Biol. 1:189. 1914-
* Osterhout, W. J. V., The permeability of protoplasm
antagonism. Science N.S- 35:112-115. 1912.
77]
Science
[Botanical Gazette, vol. 63
78
BOTANICAL GAZETTE
[JANUARY
o.oiM. 4 The resistance rose rapidly to 1170 ohms, where it
remained for 10 minutes , after which it began to fall. The results
are given in table I and fig. 1.
TABLE I
Electrical resistance of Laminar ia saccharina
Time in minutes
In KCN 0.01M in
sea water
In sea water
O
1 140
1160
1160
IISO
IOIO
910
810
710
1080
IO
O
20
O
30
1070
O
IIO
200
O
'ZOO
O
400
IO70
1200 OHMS
1000
All readings were taken at 14 C. or corrected to this temperature.
The resistance of the apparatus was 250 ohms; hence the
resistance of the tissue (the net resistance) at the start was 11 40
250=890 ohms. We may
put the permeability as equal
to the conductivity, or, for
convenience, as equal to the
conductance; hence the
permeability was 1 + 890
0.001124. The maximum
net resistance was 11 70
250=920 ohms, and the
permeability was 1^920
0.001087. Hence the loss of
permeability was (o . 001 1 24
o . 001087) -7-0.001124 = 3.3
per cent.
Similar experiments were
made with other concentra-
tions from 0.002M up to 0.381M (solution of KCN without sea
water). The results were irregular, and it is not possible to say
* This mixture had the conductivity of sea water. The sea water after the
addition of the KCN was slightly alkaline to litmus. The hydrogen ion concen-
tration of 0.01M KCN* in sea water was 1.4X10— *° as determined by the gas
chain. The alkalinity tends to make the rise of resistance less pronounced.
5 HOURS
Fig. 1
i9i 7] OSTERHOUT— POTASSIUM CYANIDE AND ETHER 79
without numerous additional experiments at exactly what concen-
tration the maximum decrease of permeability occurs. It seems
doubtful whether it amounts to much more than 3 or 4 per cent
at any concentration.
In KCN o.38iM s (without sea water) there was in some cases
a rise in resistance, followed by a rapid fall, and in other cases the
resistance did not rise, but fell from the start. It is probable, how-
ever, that in these cases there was a transitory rise which dis-
appeared before the end of the first minute, at which time the
first measurement was taken.
The experiments demonstrate that there is a temporary de-
crease of permeability instead of a temporary increase as described
by Krehan. At no concentration was a temporary increase of
permeability observed. Whenever the permeability began to
increase, it continued to increase steadily until the tissue was
dead. The concentrations employed ranged from 0.002M to
0.381M. It may be added that the method of plasmolysis, which
was employed by Krehan, cannot be relied upon to give as accurate
measurements of permeability as the determination of electrical
i resistance.
If tissue be allowed to remain in KCN until the resistance has
fallen about 100 ohms, it will often completely regain its original
resistance on being transferred to sea water. But if the resistance
be allowed to fall much beyond this, recovery is usually incomplete
and the greater the fall of resistance (beyond the point where com-
plete recovery is possible) the less the recovery.
The concentrations of KCN necessary to produce a decrease of
permeability are very much smaller than the corresponding con-
centrations of ether, chloroform, and alcohol. This accords with
the fact that it also takes less KCN to produce narcosis. The
period of decreased permeability cannot be prolonged as much by
means of KCN as by means of the other anesthetics mentioned.
This agrees with the fact that organisms can be kept longer under
* The hydrogen ion concentration was 7X10- 13 as measured by the gas chain.
This is sufficiently alkaline to cause a considerable fall in resistance (cf. Jour. Biol.
Chem. 19: 335. 1914). The concentration of KCN was determined by weighing
out the requisite amount, but owing to the presence of alkali it was really less than
0.381M.
I
80
BOTANICAL GAZETTE
[JANUARY
narcosis without injury by means of ether, chloroform, and alcohol
than by means of KCN.
*
The fact that KCN resembles typical anesthetics (such as
ether and chloroform) in producing a temporary decrease in per-
meability does not, in the opinion of the writer, show that anesthesia
is a form of asphyxiation. It seems quite probable that the
decrease of permeability and the anesthesia produced by KCN
have connection with its effect on oxidation.
Laboratory op Plant Physiology
' Harvard University
CURRENT LITERATURE
NOTES FOR STUDENTS
Oenothera genetics. — Heribert-Nilsson 1 discusses the data from his
studies of Oenothera Lamar ckiana, suggesting what he calls a Mendelian inter-
pretation of the mutating tendency of this species. The character with which
he worked was the red pigmentation found in the leaf nerves of some of his
plants and absent in others. He concludes, that the red-nerved and white-
nerved plants form a distinct discontinuous variation; that the white-nerved
plants are pure recessives and when selfed or intercrossed produce only white-
nerved plants; that a homozygous dominant is not formed, and that there-
fore a strain of pure red-nerved plants cannot be produced, but all red-nerved
plants when selfed or intercrossed will produce some white-nerved plants.
Finding the average ratio of red-nerved to white-nerved plants in O. Lamarck-
tana and most of its "mutants " to be 2 . 68 : 1, or nearly 3:1, instead of 2 : 1 as
would be expected when no positive homozygotes are formed, he adopts the
explanation proposed by Wilson in explaining the work of Cuenot with
yellow mice. According to this explanation, most of those positive female
gametes which would normally be fertilized by positive male gametes, but which
for some reason cannot be so fertilized, are fertilized by recessive male gametes.
This would produce an average ratio of the red-nerved to white-nerved plants
a little lower than would be the case under normal genetic behavior, thus
accounting for a ratio of 2.68:1 instead of 3:1. It should not be forgotten,
however, that the work of Castle removed the necessity for this interpre-
tation in the case of yellow mice, and thus lessened its value as an interpreta-
tion of this sort of deviation from expected ratios.
In "gigantea" (the gigas type) the author interprets the observed ratios
1
as modifications of 3 : 1, 15 : 1, 63 : 1, and 255 : 1, and concludes that in this type
the red-nervedness is probably produced by any one of four factors. He also
finds that the factor or factors for red leaf nerves affects other morphological and
physiological characters of the plant.
Having thus striven for a Mendelian interpretation of the behavior of
red vs. white nerves, the author presents his observations on the mutation
ratios of O. Lamarckiana and its mutants, or, as he calls them, " Kombinante,"
and suggests the following explanation of the mutating tendency of this species.
O. Lamarckiana is dependent upon a number of groups of multiple factors, the
majority of which cannot be produced in a homozygous dominant condition,
1 Heribert-Nilsson, N m Die Spaltungserscheinungen der Oenothera Lamarck-
iana. Lunds Univ. Arsskrift 12:4- 131. 1915.
81
82 BOTANICAL GAZETTE [january
and the various mutants are plants which result when one or more of these
groups are in a homozygous recessive condition. This might be represented
graphically thus: 0. Lamarckiana^ Aa Aa Aa aa; Bb Bbbbbb; Cc Cc cc cc,
etc., where in every group at least one of the factors would be present in the
positive condition. A mutant = aa aa aa aa; Bb Bb bb bb; Cc Cc cc cc, etc.,
where in at least one of the groups none of the factors are present in the positive
condition. This interpretation is thought to explain the occurrence of differ-
ent ratios of mutation, for if there were 4 such independent multiple factors
for the Lamarckiana character, a given mutant dependent upon the absence
in the following percentage : 1.2 per
cent when all of the 4 factors are heterozygous 53.7 per cent when only 3 of the
4 factors are heterozygous; n. 1 per cent when only 2 of the 4 factors are
heterozygous; 33.3 per cent when only 1 of the 4 factors is heterozygous.
At several points in his paper the author points out that since different
strains of O. Lamarckiana yield different series of mutants it cannot be an
elementary species, as DeVries claims, but must be a group of elementary
species, the free intercrossing of which makes 1
occur
ordinary
The assumption of extensive
link
mission of hereditary characters through the sperms differing from those pos-
sessed by the eggs of the same individual), and the assumption that one sort
of sperm may hinder the activities of another sort of sperm, are not in strict
Mendelian
Oenothera genetics. — Ben C. Helmick
Mutation in Matthiola annua, a "Mendelizing" species. — In a preliminary
paper under the foregoing title Frost 2 has published certain conclusions in
regard to the origin of Mendelian dominants which are sure to arouse no little
interest. Until the full account appears it will be impossible to judge of the
validity of Frost's interpretation of his discoveries, but the discoveries them-
selves are obviously of prime importance, interpret them however we may.
According to his own view, he has observed the origin by mutation of 8 differ-
ent dominant Mendelian varieties from a single strain of stocks. To show that
this would be a discovery of the highest theoretical significance, it is only
needful to point out that similar evidence is extremely meager, and in prac-
tically every case not as well attested as one might wish. The list of new
dominants which have arisen by mutation is practically exhausted when we
have mentioned Keeble's giant Primula and Collins' albinistic maize, for
the case of Gates' Oenothera rubricalyx is still in dispute.
Frost states that the individual mutations of his Matthiola cultures
obviously are not extracted recessives, but heterozygous dominants; that they
seem to be due to definite changes in the germ plasm distinct from the recombi-
ard B., Mutation in Matthiola
Amer
•
191 7l CURRENT LITERATURE 83
nations involved in ordinary Mendelian phenomena; that the mutative changes
concern various characteristics of the plant, but that the factor for each new-
type is regularly inherited as a unit, sometimes showing linkage with another
factor pair, so that we may suppose, in some cases at least, that the essential
change is limited to a portion of one chromosome. The very first test of these
conclusions would demand that the mutations reproduce the mutational type
in 75 per cent of their progeny in the first generation, and that 25 per cent of
the progeny be homozygous dominants. This condition apparently is satisfied
in the case of only 1 mutation of the 8, and until the data appear we have no
basis for an independent judgment as to whether the progenies of the second
generation were large enough to prove the point at issue. Except from this
one mutation, no homozygous mutational type has segregated from any of the
supposed heterozygous dominants. In the mind of one who is familiar with the
group of the evening primroses a suspicion naturally arises that Frost's muta-
tions are not Mendelian at all, but that they show the type of behavior familiar in
Oenothera lata DeVries, and recently discovered in mutations from O. stenomeres
and O. pratincola. These mutations always give progenies consisting of a mixture
of the parental and mutational types. In the case of 0. lata the cytological
explanation is now so well known as hardly to require comment; it certainly
suggests that a cytological examination of the Matthiola mutations would not
be amiss. Reciprocal crosses between the mutational and parental types
might also throw light on the possible analogy between the evening primroses
and stocks, for in such types as Oenothera lata mutational characters are
carried only by part of the female gametes, and by none of the male gametes.
All that Frost tells about the Matthiola mutations so exactly parallels what is
found in Oenothera that one can hardly refrain from suggesting, in the absence
of data supporting his own interpretation, that instead of discovering new
Mendelian dominants he has found in a widely distant group some of the per-
plexing phenomena which critics of the mutation theory persist in regarding
as peculiar to Oenothera. More and more facts are coming to light in groups
other than Oenothera which do not fall into line according to Mendelian expec-
tations. As an example of what looks like mutation in the DeVriesian sense,
one thinks of the rogues of peas, investigated by Bateson; as an example of
matroclinic, non-segregating hybrids, quite comparable to those of Oenothera,
we have the cases in Primula, recently reported by Pellew and Durham.
If the type of heredity shown by Oenothera lata were found to apply to the
mutations of Matthiola, it would be almost as interesting as the discovery of
new Mendelian dominants. — H. H. Bartlett.
Respiration in succulents.
exhibit
in their respiratory processes and periodic changes in acidity with light and
darkness has been known for a long time. Richards* has investigated these
* Richards, Herbert M., Acidity and gas interchange in cacti. Carnegie
Inst., Washington, Publication no. 209. pp. 107. 1915.
84 BOTANICAL GAZETTE [january
periodic acidity changes and the respiratory ratios in cacti, a group heretofore
not sufficiently studied. Extensive work has been done, principally with
Opuntia versicolor, with results in general agreement with what is already
known regarding respiration in succulents. The paper presents a large mass
of data, and considers the influence of light, temperature, oxygen supply, and
wounding on the acidity of the tissues, and devotes considerable space to the
relation of acidity, light, temperature, oxygen, etc., to the rate and ratio of
gas interchanges. The production of the acid, chiefly malic acid in cacti, is
thought to be due to lack of oxygen in the tissues, owing to anatomical struc-
tures which, to restrict transpiration, restrict the other gas exchanges as well.
During the night the acid accumulates, because the chief factors capable of
causing deacidification, namely, light, high temperature, prolonged darkness,
and unusually high oxygen pressures, are absent.
The true respiratory quotient for cacti is low, and can be measured accu-
rately only when acidity is stationary or rising. For during falling acidity,
the approach of the ratio to the typical ratio, unity, is not real, because the in-
creased C0 2 is furnished merely by the decomposition of the acid, which is not
considered a respiratory process. Some of the minor points brought out are
that while C0 2 production closely parallels rise and fall of temperature, it lags
behind by about an hour, maximum and minimum C0 2 production being
reached about an hour later than maximum and minimum temperature; and
that total acidity increases more rapidly than the acid concentration of the
juice. This is reasonably traced to greater hydration of the colloids in the
■
presence of the acids, and to an increased osmotic pressure in. the cell sap
leading to greater turgidity.
The main point of interest to physiologists is the interpretation of the
phenomena, which differs somewhat from that of Nathansohn, who looked
upon the breaking down of the acids by day as a completion of the respiratory
process at a time when C0 2 could be used in photosynthesis. This view makes
the C0 2 production during deacidification a source of respiratory energy, and
at the same time of great biological significance in conserving the raw materials
for photosynthesis. Richards considers the acid the end product of respira-
tion rather than an intermediate product. The breaking down of the acid by
day is due chiefly to light, aided by the accompanying high temperature. The
reaction is photolytic and not respiratory, probably takes place in the cell
sap, and therefore probably yields its energy not in connection with the living
protoplasm. He points out that C0 2 production during deacidification may
be so rapid as to exceed photosynthetic use of the gas, and states that
"whatever of energy there may be from the final oxidation of the acid
outside the sphere of protoplasmic activity is simply the result of anatomical
peculiarities of the plant, the advantages of which may well outweigh this
loss."
The whole problem of acidity and gas exchange under life conditions is
necessarily a very complex one because so many variable factors are involved,
1917] CURRENT LITERATURE 85
and a careful reading of the paper emphasizes this fact. Conclusions must
therefore be drawn with considerable care. — Charles A. Shull.
Insects and plant diseases. — Although both botanists and entomologists
have realized for a long time that insects are carriers of organisms of plant
diseases, very little attention has been given to the study of the subject.
However, there is now a tendency to take up this line of investigation. Four
papers have come to the reviewer's desk recently.
Rand*
Smith
both
summer and the winter carrier of the Bacillus tracheiplilus which causes the
wilt of cucumbers and other cucurbits.
In a later paper by Rand and Enlows,* the authors not only confirm the
conclusions given by Rand in the first paper, but also include the 12-spotted
cucumber beetle (D. duodecimpunctata) as an important summer carrier of this
organism. In experiments by the same authors, the squash bug (Anasa
tristis), the flea beetle (Crepidodera cucumeris), the melon aphis (Aphis gossypii),
and the 12-spotted lady beetle (Epilachna borealis) did not transmit the
disease.
Another paper by Hyslop 6 on Triphleps insidiosus and corn rots gives
conclusive evidence that this insect is the carrier of the fungi causing ear rots.
In view of the fact that this insect has been considered beneficial since about
188 1, Hyslop's studies are of more than ordinary interest.
A fourth paper by Stewart and Leonard 7 records their results with a
number of experiments and comes to the conclusion "that all of the sucking
bugs found in the nursery are of more or less importance in producing fire
blight infections and must be considered tout ensemble. The relative importance
of each species is difficult to determine. By virtue of their method of feeding
and prevalence during each season, certain species are undoubtedly more
destructive than others. On the other hand, under special conditions when
a certain species is found in large numbers it may become of considerable
importance. Usually the tarnished plant bug is more injurious than the leaf-
hopper from the fact that the greater percentage of leaf-hopper punctures
occur in the leaf tissue. ,, — Mel T. Cook.
4 Rand, F. V., Dissemination of bacterial wilt of cucurbits. Jour. Agric.
Research 5:257-260. 1915.
s Rand, F. V., and Exlows, Ella, M., Transmission and control of bacterial
wilts of cucurbits. Jour. Agric. Research 6:41 7~434- 1916.
6 Hyslop, J. A., Triphleps insidiosus as the probable transmitter of corn ear rot
(Diplodia sp. Fusarium). Jour. Econ. Entomology g:435~437- I 9 l6 -
'Stewart, V. B., and Leonard, M. D., Further studies on the r6le of insects
in the dissemination of fire blight bacteria. Phytopath. 6:152-158. 1916.
86 BOTANICAL GAZETTE [January
Taxonomic notes. — Bailey 8 has published in advance some of the changes
in nomenclature that will appear in the Standard Cyclopedia of Horticulture.
The changes selected for publication involve the names of ioo species and
varieties, and some of the changes affect North American species. For example,
the retention of Mains in Pyrus involves changes in 24 names; while a new
interpretation of Statice as contrasted with Limonium calls for changes in 43
names. The author pays his respects to a certain type of taxonomic work as
follows: "It has been the desire, in the compilation of the cyclopedia, to accept
new generic limitations with caution. The temper of the present times is to
find differences, as opposed to the tendency of the immediately preceding
1
workers to find agreements. The analytic intention is the mark of syste-
matic work in this generation, as the synthetic intention was the mark of the
past generation. There is reason to expect a return from the method of dis-
union to the method of relationships; and as a work designed for the use of
horticulturalists, who cannot be skilled in bibliography and pedantry, should
be conservative, I have thought it best, so far as possible, to avoid unnecessary
and fantastic sub-divisions."
Conard 9 has revived the discussion concerning certain generic names of
our water lilies. With the help of even the more conservative manuals, we
were accustoming ourselves to say Castalia when we thought of Nymphaea,
and to say Nymphaea when we thought of Nuphar. Now Conard has shown
that the valid generic name for the white water lilies is Nymphaea after all,
and for the yellow pond lilies is Nuphar.
Fernald 10 has discussed the species of Sabatia usually recognized as
occurring in New England, and has described a new species (S. Kennedyana)
occurring in Massachusetts and Rhode Island. — J, M. C.
Life cycles of bacteria- — Lohnis and Smith, 11 in a preliminary communi-
cation, present some of their conclusions from a study of 42 strains of bacteria.
All of these strains showed life cycles "not less complicated than those of other
microorganisms "; and the authors are inclined to believe that this may be
true of all species of bacteria. The forms studied live alternately in an organ-
ized and in an amorphous stage, the latter being called a "symplastic" stage,
because in this stage the separate cells undergo "a thorough mixing." From
this "symplasm" new individual cells arise in various ways. In all cases what
are called " regenerative units" become visible, which increase in size, and
* Bailey, L. H., Nomenclatorial transfers. Rhodora 18:152-160. 1916.
9 Conard, Henry S., Nymphaea and Nuphar again. Rhodora 18:161-164,
1916.
10 Fernald, M. L., The genus Sabatia in New England. Rhodora i8:i45~ x 5 2 '
pi. 121. 1916.
11 Lohnis, F., and Smith, N. R., Life cycles of the bacteria. Jour. Agric. Research
6:675-702. pis. 1-7. fig. 1. 1916.
1917] CURRENT LITERATURE 87
later "either by germination or by stretching become cells of normal shape."
A direct union of two or more individual cells was also observed, the significance
of which was not studied. The authors state that "the life cycle of each
species of bacteria studied is composed of several subcycles, showing wide
morphological and physiological differences. They are connected with each
other by the symplastic stage. Direct changes from one subcycle into another
occur, but they are rather rare exceptions." It is obvious that if such life
cycles are established for bacteria in general, a new field is opened up in bacte-
riology. — J, M. C.
Cane sugar and translocation. — Boysen- Jensen 12 concludes that cane
sugar plays an important role in the germination of pea seeds. In the first
stages of germination the cane sugar present in the ungerminated seed is used
both as building and respiratory material, as is evident from its reduction in
amount during the first few days of the process. In the second stage of ger-
mination cane sugar is the translocation form of the starch, as is shown by the
following facts: (1) there is a higher concentration in the cotyledons than in
the axillary organs; (2) the concentration rises with time in the isolated
cotyledons and falls in the isolated axillary organs; (3) only inconsiderable
amounts of reducing sugars are present in the cotyledons. The author
cites several investigations showing the frequent appearance of cane
sugar as the translocation form of starch, and concludes by saying
that either monosaccharides or disaccharides may be translocation forms
of starch, depending upon the character of the plant part. — William
Crocker.
Cabbage yellows. — Gilman 13 has investigated this disease and the relation
of temperature to its occurrence. It is a wilt disease caused by Fusarium
conglutinans, which is a facultative parasite living in the soil, and under certain
conditions becoming destructive to cabbage. It has a high optimum tem-
perature and is very resistant to drying. Inoculation experiments were
largely successful in inducing the disease, the failures being due obviously to
variations in the virulence of the cultures and in the susceptibility of the host.
Control plants remained entirely free from the disease. The appearance of the
characteristics symptoms is dependent upon a temperature of 17-22 C. or
above, lower temperatures preventing the occurrence of the disease. Field
observations through three seasons confirmed this relation between the occur-
rence of the disease and high temperature. — J. M. C.
"Boy
bei der Keimung von Pisum sativum. Jahrb. Wiss. Bot. 56:43 1-446. 1915- Pfeffer's
Festschrift.
» Gilman-, J. C, Cabbage yellows and the relation of temperature to its occurrence.
Ann. Mo. Bot. Gard. 3:25-84. pis. 2. figs. 21. 1916.
ilduhg des Rohrzuckers
88 BOTANICAL GAZETTE [january
Rot of potato tubers. — Hawkins, 14 continuing his studies on the effect of
various fungi on their hosts, has investigated the effect of Fusarium oxysporum,
F. radicicola y and F. coeruleum on the sugar content, both sucrose and reducing
sugar, pentosans, methyl pentosans, galactans, dry matter, starch, and crude
fiber of the potato tuber. The crude fiber content of the tubers was not reduced,
m
starch and methyl pentosans were not affected appreciably, while the content
of the other substances was reduced. It is interesting from the point of view
of resistance to fungus invasion that the least digestible forms occur in greatest
proportions in the skin and cortical regions of the tuber. Fusarium oxysporutn
and F. radicicola were found to secrete sucrase, maltase, xylanase, and diastase.
The diastase, like the malt diastase that Brown and Morris worked with, is
incapable of attacking ungelatinized potato starch. — George K. K. Link.
Phytoplankton of the oriental tropics. — Ostenfeld 1 * has published a list
of the phytoplankton of one of the straits of the Malay Archipelago. The
list is based chiefly upon a large collection of drawings made by P. Th. Juste-
sen in 1909 and 1910, while residing at one of the small military stations in the
Dutch Indies. The list includes 100 species, the largest group being the
diatoms, with 56 species representing 23 genera. The Peridiniales constitute
the other large group, including 40 species in 11 genera, the largest genera
being Ceratium with 17 species, and Peridinium with 12 species. The general
character of the plankton is said to be that of a "tropical neritic plankton/'
very much like the plankton examined by Cleve and Ostenfeld from the
Malay Archipelago and the Gulf of Siam. — J. M. C.
Branched prothallia. — Miss Wuisx 16 has investigated the early stages of the
gametophytes of the Polypodiaceae in reference to branching, subjecting them
to various culture conditions. She observed branching in cultures of 15 species
representing 9 genera. Branching, which was both dichotomous and mono-
podial, was not a response to any one type of culture medium, but appeared
on distilled water, on soil, and on various nutrient solutions. Branches did
not appear at any definite period in the life history of the gametophyte, but
were formed by any cell of the filament, by divisions of the last cell of the fila-
ment, and from the margin and apex of the expanded portion of the pro thallium.
The author has concluded that a definite relation exists between branching
and nutrition. — J. M. C.
14 Hawkins, Lon A., Effect of certain species of Fusarium on the composition
of the potato tuber. Jour. Agric. Research 6:184-196. 1916.
^Ostenfeld, C. H., A list of phytoplankton from the Boeten Strait, Celebes.
Dansk Bot. Arkiv 2:no. 4. pp. 18. figs. 10. 1915.
x6 Wuist, Elizabeth D., Branched prothallia in the Polypodiaceae. Bull. Torr.
Bot. Club 43:365-383- figs. 15. 1916.
•
VOLUME LXIII
NUMBER 2
THE
Botanical Gazette
FEBRUARY 1917
A comparative study of winter and summer
LEAVES OF VARIOUS HERBS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 224
I
J. P. Stober
Introduction
The structure of most plants varies with the habitat and even
with the varying conditions of the same habitat. This has been
emphasized by Grevillius, 1 Chermezon, 2 Cowles, 1 Starr, 4
and others. Grevillius made an extensive comparative study of
vegetation growing on the island Oland. He compared the plants
of a dry, rocky, treeless plain (alvar) with the same species growing
*n favorable regions. The former he calls alvar forms; the latter,
normal forms. The alvar forms, in general, were more hairy and
had a more highly cutinized and thicker epidermal wall, a more
compact palisade parenchyma, and more closely crowded stomata
than the normal forms.
These structural peculiarities due to environmental changes
may be observed readily in almost any plastic plant. Oenothera
1 Grevillius, A. Y., Morphologisch-anatomische Studien iiber die xerophile
Phanerogamen vegetation der Insel Oland. Bot. Jahrb. 23:24 108. 1897.
2 Chermezon, H., Recherches anatomiques sur les plantes littorales. Ann. Sci.
Nat. Bot. 12:117-313. 1910.
* Cowles, H. C, The ecological relation of the vegetation of the sand dunes of
Lake Michigan. Bot. Gaz. 27:95-117, 167-202, 281-308, 3 6 *-39 r - l8 99-
4 Starr, Anna M., Comparative anatomy of dune plants. Bot. Gaz. 54:
26 5"-3°5- JO 12 -
89
9<D BOTANICAL GAZETTE [February
biennis, for example, when growing in a dry, sterile soil and exposed
to strong wind and maximum sunlight, is found to have smaller
and thicker leaves, more perfectly developed palisade parenchyma,
a more hairy and a more densely cutinized epidermis, and, in
general, a more xerophytic structure than the same species growing
under more favorable conditions.
A similar structural difference is apparent in summer and
winter leaves, or in stem and rosette leaves. Winter leaves, as
the name implies, exist during the winter, which, in our latitude,
is the most unfavorable season of the year. During the winter
transpiration becomes relatively excessive because of the reduced
rate of absorption, and plants are thus put to the severest test.
Sometimes for days at a time the ground is frozen and absorption is
practically zero; while during the warmest part of the day con-
siderable transpiration may take place. The plant is thus exposed
to the danger of desiccation. Moreover, during the night the most
exposed leaves may freeze hard. Toward noon of the following
day they may thaw out, presenting a wilted condition as if killed
by scalding. However, it is surprising how quickly such leaves
will revive as conditions again become more favorable. No sooner
is the absorption of soil water resumed than the leaves once more
become turgid and resume their wonted appearance, apparently
none the worse for the ordeal through which they have passed.
Since winter leaves are exposed to such severe conditions, it
would be natural to suppose that they must be quite xerophytic
in structure. While this is true to a certain extent, in some respects
they are less exposed to unfavorable conditions than stem leaves.
This is especially true of winter leaves occurring in rosettes. In
rosettes the internodes are extremely short and the leaves thus
become closely crowded and overlapping. Since epinasty pre-
vails during the winter, these overlapping leaves lie almost flat on
the ground, thus affording maximum protection for each other from
sudden changes of temperature, as well as from high winds and
excessive transpiration. It is seldom that winter leaves die as the
direct result of freezing, and when it is borne in mind that such
leaves have a low water content and a high osmotic pressure, thus
insuring easier absorption of soil water, the protection would seem
/
igi7l STOBER— WINTER AND SUMMER LEAVES 91
am
)le, regardless of any special protective structures. The stem
leaves, on the other hand, are usually borne some distance above the
ground and exposed to greater intensity of light, stronger winds,
and greater extremes in temperature, humidity, and transpiration.
Method of study
Most of the plants used in this comparative study were collected
in the region about Chicago; the remainder, in eastern Penn-
sylvania. In order to simplify matters, all winter leaves, whether
produced in
runners, or on basal
designated
be designated as cauline or stem leaves.
Leaves for study were killed, fixed, and preserved in a 4 per
cent solution of formaldehyde in 50 per cent alcohol. Delafield's
haematoxylin was used as a general staining reagent. Sections
were also treated with chloriodide of zinc, the cellulose wall
turning blue, while the cuticle and cutinized portions of the
epidermal wall turned yellow\ Alcannin tincture
I of zinc.
yellow. Alcannin tincture imparts a pink
much slower in its action than chloriodide
Unless otherwise specified, all observations were made on the
middle of the leaf, from the midrib to the margin. All observations
and measurements were made with f , |, and T V in. (oil immersion)
objectives, and with a 1 in. micrometer eyepiece with divisions of
0.1 mm. Camera lucida drawings were made of portions of the
epidermis for measurement and comparison of epidermal cells and
stomata. Chloral hydrate was used as a clearing agent for leaves
to facilitate the study of air spaces and packing of mesophyll tis-
sues. Most measurements and counts represent an average of
5-20, depending upon the degree of variability of the objects meas-
ured. Measurements are expressed in microns, and counts rep-
resent the number in the field under low or high power, which is
indicated in each case.
same species (
cases where the plants could readily be secured) were studied at
different times and the results compared. These results varied
only slightly when the plants came from the same habitat, but
usually differed considerably in plants from different habitats.
Q2
BOTANICAL GAZETTE
[FEBRUARY
With such a tendency to variation in plants, few measurements
and counts can be regarded as absolutely fixed, but the final results
in any case do not materially affect the principles involved.
Epidermal hairs
There is considerable variation in the kind, number, size, and
distribution of epidermal hairs, not only in different plants of the
same species, but also on different leaves of the same plant, or even
on different parts of the same leaf. Some plants, such as Oenothera
biennis, vary greatly when grown under different physical condi-
tions. In a low, moist, and comparatively shady habitat the leaves
of Oenothera are thin, and the hairs rather weak and comparatively
few and scattered. On a dry slope or bank along the roadside,
the leaves are decidedly thicker, and the hairs stouter and very
much more abundant; while under intermediate conditions corre-
sponding variations have been observed.
Oenothera is an extremely plastic plant, responding readily to
changed conditions of environment. Leonurus Cardiaca, Lepidium
virginicum, Cap sella Bursa- pastor is, and others also show some
variations, but not to the same extent as Oenothera. Verbascum
Blattaria, on the other hand, is glabrous no matter under what
physical conditions it may be growing. Occasionally, when grow-
ing on a dry bank along a dusty roadside, a few hairs may be
found on the ventral side of the midrib of the lower stem leaves and
upper rosette leaves. This plant is extremely rigid and does not
at all, or but slightly, yield to changing conditions of environment.
It is perhaps a good illustration of a congenital mesophy te.
In studying the number and distribution of hairs, Oenothera
biennis y O. rhombipetala , Leonurus Cardiaca, Lepidium virginicum,
Cap sella Burs a- past or is, and Hieracium paniculatum were selected
as types. Care was taken to collect both the stem and rosette
plant of each species in the same or as nearly the same habitat as
possible. Five plants of each species were studied, and the counts
for each particular kind of hairs were averaged and tabulated.
The field of the low power of the microscope was adopted as the
unit area of observation, and the average of 5 or more counts was
taken as the number for each area under observation.
s
1917] STOBER— WINTER AND SUMMER LEAVES 93
From the tabulated results of observations made on these
species of plants and a careful study of a number of other species,
the following conclusions can be formulated. (1) Epidermal hairs
most
stem
rosette leaves. On the basal leaves of both stem and rosette are
found the smallest number of hairs. (2) Hairs are also more
abundant on the lower than on the upper surface of the leaf,
usually being most abundant on the ribs, veins, and margin of the
leaf. (3) Hairs are most abundant toward the base of leaves,
although in basal stem and rosette leaves the reverse is usually the
case. (4) Young leaves are more hairy than older ones. This
may be due partly to the fact that in young immature leaves the
epidermal cells have not yet reached their mature size and there-
fore the hairs will of necessity be more crowded than in a mature
leaf. This diminished hairiness in older leaves also may be due in
part to the fact that hairs in the course of time may break off, or
for some reason or other drop off, and thus reduce the number per
unit area of surface. (5) Exposure to sun, wind, and other desic-
cating influences tends to increase the hairiness in the upper stem
leaves. Transpiration, wind, moisture, and character of soil are
undoubtedly potent factors in determining hair production, but
that these are not the only factors is clearly shown by the fact
that
from buds, and therefore most
most hairv, sometimes
most hairy
where the leaf is most protected from those influences that would
ordinarily tend to produce hairiness. It is difficult also to see why
Verbascum Thapsus and V. Blattaria should grow side by side, the
other extremelv hairv. So far as hairiness
the
seem
tal meso
It is difficult also to see that hairiness is beneficial to plants,
and that these epidermal outgrowths protect the plant against
excessive transpiration, against the ravages of animals and para-
sites of various kinds, against excessive sunlight, etc., when Ver-
bascum Blattaria, entirely devoid of hairs and with only a >lightly
94 * BOTANICAL GAZETTE [February
thicker epidermal wall, is fully as successful in the struggle for
existence as V. Thapsus growing by its side, so thoroughly pro-
tected by an abundance of epidermal hairs. It is not difficult to
see that the woolly coating may be advantageous to young leaves,
just emerging from the bud ; but it is extremely difficult to find any
advantage in the few simple and stellate hairs scattered over the
leaves of Lepidium and Cap sella.
Stomata
In over two-thirds of all the plants studied the stomata were
found to be more abundant on stem than on rosette leaves. Some-
times this difference in number is only slight, but sometimes, as in
Mitella diphylla, Lepidium virginicum, Monarda punctata, Aquilegia
canadensis , Campanula rotundifolia, Capsella Bursa- pastoris, and
Geum album , this difference is considerable. Stomata are also
most abundant on the lower side of the leaf. This is true of about
80 per cent of all the plants studied.; This difference is most pro-
nounced in leaves that have their upper and lower sides well devel-
oped, such, as the broad mesophytic rosette leaves. Narrow,
xerophytic stem leaves, such as have both sides almost equally
exposed to light and air, have approximately the same number of
stomata on both sides. The more xerophytic the leaves, the
greater are the number of stomata as compared with the corre-
mes
>phytic leaves. As a rule, the size of stomata is
correlated with the number. The larger the number of stomata
on a given leaf surface the smaller they are. This was found to be
true in over 60 per cent of the specimens compared. Broad meso-
phytic rosette leaves have fewer but larger stomata on a given sur-
face than the corresponding narrower, more xerophytic stem leaves.
In these there is a larger number of stomata per unit surface, but
the stomata are decidedly smaller in size.
There also seems to be a correlation between the number and
size of stomata, and the size of epidermal cells. The broad rosette
leaves have, as a rule, larger epidermal cells. With these larger
cells are associated fewer but larger stomata.
Anterior-posterior orientation of stomata is noticeable in the
stem leaves of Campanula rotundifolia, Linaria canadensis, Arabis
(HI
1917] STOBER— WINTER AND SUMMER LEAVES 95
lyrata, A. brachycarpa, A. laevigata, and Satureja glabra; and in
both stem and rosette leaves of Artemisia candata and Lechea
villosa. All these leaves are linear or oblong. Not all linear or
oblong leaves have their stomata longitudinally oriented, but such
1
orientation is characteristic of linear and oblong leaves, especially
if the epidermal cells are longitudinally elongated.
The stomata of the species investigated are not sunken below
the surface in either stem or rosette leaves, except in the sand dune
xerophytes, Artemisia canadensis and A. caudata, where they are
depressed about half the thickness of the epidermis. In a few
instances the stomata seemed even to be elevated slightly above
the surface. In Mitella diphylla, Leonurus Cardiaca, Aquilegia
canadensis, and Chelidonium majus, the stomata are confined to
the ventral surface of the leaf.
Rosette stomata are not only larger but also more elongated
than stem stomata. Stem stomata are not only smaller but also
more nearly round than rosette stomata. Perhaps the number
of stomata ought to be correlated with the mass of the chloren-
chyma. The smaller number of stomata in the broad, thin
(frequently thicker than stem leaves), mesophytic rosette leaves,
when compared with the smaller mass of chlorenchyma to be
aerated, may be relatively as abundant as the larger number per
unit surface in the long, narrow, thick xerophytic stem leaves,
where a larger mass of chlorenchyma must be aerated through a
given surface area; that is, the number of stomata is correlated
with the amount of chlorenchyma to be aerated, and not with
the mere surface area of the leaf. The number of stomata also
seems to be correlated with the thickness of the cuticle and
cutinized outer wall of the epidermis. The greater the thickness,
the less is the possibility of gases passing through, and the greater
is the need for stomata. It is probably for these two reasons, the
greater mass of chlorenchyma per leaf surface and the greater
thickness of the cuticle and cutinized outer wall of the epidermal
cells, that xerophytic leaves have an increased number of stomata
in a given surface area. The relatively thinner and frequently
more shaded rosette leaves are broader and have a thinner cuticle,
a thinner outer epidermal wall, and a greater development of air
96 BOTANICAL GAZETTE [February
lacunae. Such leaves need fewer and are provided with a smaller
number of stomata. Stomata are not needed for transpiration, since
transpiration is believed to be a necessary evil. It seems strange,
therefore, that in xerophytic leaves, where there is effected the
greatest protection against the loss of water by the development of
a thick cuticle and a thick outer epidermal wall, there should be
the development of a large number of stomata, thus facilitating the
loss of water from the plant through stoma tal transpiration.
In leaves whose outer epidermal wall and cuticle are thin, there
is less need of stomata to facilitate exchange of gases in photo-
synthesis and respiration, since under such circumstances consider-
able interchange of gases can take place through the epidermis.
There is no doubt that mesophytic rosette leaves with a reduced
number of stomata have an ample supply of stomata to meet their
needs. Moreover, rosette leaves are close to the soil and are there-
fore more advantageously situated for the intake of carbon dioxide
than are stem leaves. In stem leaves the pressure of C0 2 cannot
accumulate beyond 0.0003 A, or about o. 22 mm. Hg, since above
this pressure it diffuses outward. But in rosette leaves close to the
ground, where the exhalation of C0 2 from the soil often increases
the C0 2 to 10 or more times the normal amount, a much higher
pressure of C0 2 may accumulate. This increased amount of C0 2
in rosette leaves is available for carbohydrate synthesis in all cases
where the leaves are not too much shaded. But since plants under
normal conditions receive much more energy of sunlight (about
4 or 5 times as much) than is necessary to synthesize the small
amount of available C0 2 , rosette leaves are most advantageously
situated for photosynthesis in spite of the reduced number of sto-
mata and the diminished amount of light. These facts have an
important bearing upon the development of chlorenchyma and
air spaces in rosette leaves.
Epidermal cells
In monocotyledonous plants the epidermal cells are usually
elongated. In dicotyledonous plants they are generally elongated
along the ribs and larger veins, but elsewhere they may be polygo-
nal and nearly isodiametric in outline, or entirely irregular. The
1917] STOBER— WINTER AND SUMMER LEAVES 07
shape of the leaf, to a certain extent, determines the shape of the
epidermal cells. In narrow and elongated, or linear, leaves, such
as those of the stems of Arabis brachycarpa, A. lyrata, Linaria
villosa, and Artemisia caudata, the epidermal cells also are elongated
or linear. In such elongated or linear cells the lateral walls are
quite regular. The upper epidermal cells, however, are usually
more regular than the lower, except in such stem or rosette leaves
as are almost equally exposed to light. Such leaves have both
surfaces almost equally exposed to desiccating influences, hence the
shape and size of the epidermal cells on both sides of the leaf are
practically the same. This is very apparent in such xerophytic
stem leaves as those of Linaria villosa, Arabis lyrata, A. brachy-
carpa, A . laevigata, and Campanula rotundifolia.
The shape and size of epidermal cells vary greatly, not only in
different species and in individuals of the same species, but even
in stem and rosette leaves of the same individual. There may
even occur considerable variation in different parts of the same leaf.
Thus in Leonurus Cardiaca the sinuosity of the lateral walls increases
slightly from the lower to the upper stem leaves. In Geum album
the sinuosity seems to increase from the upper to the lower rosette
leaves. In Lepidium virginicum the sinuosity is practically the
same from the upper stem leaves. to the lowest rosette leaves.
However, the sinuosity in the lower epidermis, in the case of
Lepidium, is greater than in the UDDer eDidermis. The lateral
epidermal cells are, as a rule, more sinuous t
epidermis, and in the majority of instances
per cent)
stem
culminates under the most
conditions. Increased transpiration tends to produce relatively
straight lateral walls. Hence we find the epidermal walls of the
stem
than the lower side.
th stem and rosette leaves less sinuous
ace, since stem leaves are more xerop
d the upper side of leaves more xerop
Sinuosity of lateral epidermal walls i
significance to plants. It may add a lit
•t>
epiderm
98 BOTANICAL GAZETTE . [February
for substances passing from cell to cell. No chloroplasts are
present in epidermal cells except in guard cells, and, to a slight
extent, in winter leaves of Leonurus Cardiaca.
As to size, the upper epidermal cells are larger than the lower,
and, with few exceptions, the epidermal cells of rosette leaves are
larger than those of stem leaves. In 80 per cent of all observations
made the epidermal cells of rosette leaves were found to be larger
than those of stem leaves. The size of epidermal cells is somewhat
correlated with the size of leaves, the larger leaves haying the
larger epidermal cells; but there are so many exceptions to this
that such a general statement is not warranted.
The vertical diameter of epidermal cells is greater, as a rule,
in rosette than in stem leaves (true of 80 per cent of cases), in the
upper than in the lower epidermis, and usually increases from
the apex toward the base of the leaf. In the middle rosette leaves
the maximum diameter is usually found in the middle of the leaf.
In Capsella there is a gradual increase from the upper stem to the
lowest rosette leaves. As a rule, the maximum diameter is attained
in both the middle stem and rosette leaves.
Blade, epidermal wall, and cuticle
The blade decreases in thickness from the apex to the base
of the leaf. It also decreases from the upper to the basal leaves.
This is less apparent in middle leaves, where the leaf sometimes
increases in thickness from apex to base, or where the maximum
thickness of the blade occurs in the middle of the leaf. Those
most
Rosette
yes are thicker than stem leaves, owing to a greater development
spongy parenchyma. This is true more particularly of the
middle and basal stem
stem
especially the apical portions of those leaves, are frequently thicker
than the corresponding portions of rosette leaves. The blade, in
most instances, also appears thicker than the blades of stem leaves.
Notable exceptions are Arabis lyrata, A. laevigata, Linaria cana-
densis, Leonurus Cardiaca, Campanula rotundifolia, and Monarda .
punctata. All these species, except Leonurus Cardiaca, have either
linear or oblong lanceolate stem leaves, while the basal leaves
1917] STOBER— WINTER AND SUMMER LEAVES 99
are broad and thin.
almo
m
The outer epidermal wall is decidedly thicker in stem tha
rosette leaves. In each of the 3 types considered, Lepidium
ginicum, Capsella Bursa- pastor is, and Chrysanthemum Leucat
and
from each other, thus exDosiner them
the
to air, sunlight, and desiccating winds. The rosette leaves, on
other hand, are close to the ground and considerably shaded;
hence we should naturally expect this difference in thickness of
epidermal cell walls. There is a slight tendency for the wall to
diminish in thickness from the apex to the base of the leaf. The
maximum thickness is usually reached in middle stem and apical
rosette leaves, while the maximum thinness is probably to be found
in the lowest rosette leaves. The outer epidermal wall on the
upper surface of the stem leaves is but slightly thicker than that
of the lower, especially in those upper stem leaves that grow
obliquely upward so as to expose both surfaces almost equally. In
the lower stem and rosette leaves this difference is much greater,
the epidermal wall on the lower side being considerably thinner.
The thickness of the cuticle varies with the thickness of the
outer epidermal wall, the thickest wall having the thickest cuticle.
The cuticle of the stem leaves of the types treated is decidedly
thicker than that in the rosette leaves. It is thicker on the upper
than on the lower surface of the leaf, except in the upper stem
leaves, where both surfaces are about equally exposed. Here
the lower cuticle is almost as well developed as the upper. The
greatest decrease in thickness of cuticle is observable in the basal
rosette leaves.
In interpreting the facts set forth it must be borne in mind that
only middle stem leaves are compared with middle rosette leaves,
and that whatever conclusions may be deduced must rest upon
this comparison. Most plants have their rosettes better protected
than their shoots. In 83 per cent of 30 plants observed, the cuticle
is thicker in rosette than in stem leaves. In at least 75 per cent
of the number the epidermal wall is also thicker in rosette than
in stem leaves. Thus it seems that when the effective means of
*
ioo BOTANICAL GAZETTE , [February
protection of the middle stem leaves and the middle rosette leaves
are compared, the preponderance of protection is in favor of the ro-
sette leaves. However, it must be borne in mind that the difference
in thickness of wall and cuticle in a number of instances is so slight
as to be almost negligible. Moreover, in notable instances the stem
leaves have a decidedly thicker wall and cuticle. This is true of
Chrysanthemum Leucanthemum, Capsella Bursa-pastoris, Artemisia
caudata, Satureja glabra, Scutellaria parvula, and others. Chrys-
anthemum has broad, spatulate rosette leaves on long slender
petioles, while the stem leaves are oblong or oblanceolate, and have
a decidedly xerophytic form and structure. The stem leaves of
Lepidium, Capsella, Satureja, and, to a certain extent, Scutellaria,
in like manner have a decidedly xerophytic form and structure as
compared with their corresponding rosette leaves. Artemisia is
one of those sand dune xerophytes whose stem and rosette leaves
are finely dissected and almost equally exposed, and hence almost
equally xerophytic in form and structure. In such mesoxerophytes
as Verbascum Thapsus, whose leaves are thoroughly protected by
a woolly coat of branching multicellular hairs, the difference in
protection of stem and rosette leaves is also slight! Some plants,
therefore, seem to have xerophytic shoots and mesophytic rosettes;
others show a tendency to xerophytic rosettes and mesophytic
shoots; while in still others the distinction is not evident.
Chlorenchyma
The apical, middle, and basal stem and rosette leaves of certain
plants were studied with a view to determining the similarities and
differences of the chlorenchyma of the corresponding regions of the
stem and rosette leaves of the same plant. For example, an
apical stem leaf and an apical rosette leaf would be selected for
comparative study. Sections through the apical region of the
stem leaf were then studied and the results compared with those
obtained from a similar
rosette leaf. Sections th
the
the
leaves were similarly studied and compared. After the apical
leaves were thus studied, the middle stem and middle rosette leaves,
as well as the basal stem and basal rosette leaves, were similarly
1 9 1 7 ] 5 TOBER—WIN TER A ND S UMMER L EA VES i o I
studied. The thickness
ma
of the palisade layers of cells, and the average size of the cells of
each layer, together with the size, shape, and arrangement of the
cells of the spongy parenchyma, were the leading points of obser-
vation in this comparative study. All measurements are expressed
in microns, and were made approximately 8oo m from the midrib
of the leaf. For want of space the tabulated results cannot be
given; a general summary in each case must suffice.
Lepidium virginicum. — In the upper stem leaves the palisade
parenchvma is almost eauallv develoDed in both the uDDer and
lower side of the leaf. This may
stem
illuminated. In the middle stem leaves a lower palisade tissue is
found only in the apical region of the leaf. No lower palisade
layers are found in the lower stem leaves or in any of the rosette
leaves. The palisade layers of the upper stem leaves are quite
compact. The cells reach a maximum length in the middle stem
leaves. In the basal stem leaves the cells become la
more
rounded, the layers are less closely packed and less definitely organ-
ized. The palisade cells of the rosette leaves are larger, having
a decidedly greater diameter, and on the whole are less compactly
arranged than in stem leaves. The upper and middle stem leaves
have the thickest outer epidermal wall and cuticle. This is also
true
epider
basal leaves
tern
Capsella Bur$a-pastoris. — The outer epidermal wall of stem
leaves is thicker in the upper than in the basal leaves, attaining a
maximum in the middle leaves. The cuticle is proportionally
thickest in the upper leaves and thinnest in the proximal part of the
basal leaves. Similar conditions obtain in the rosette leaves,
except that the contrast between apical and basal cells is less pro-
nounced. Palisade tissue is best developed in both upper stem
and upper rosette leaves. Palisade cells are slightly longer and
decidedly thicker in rosette than in stem leaves. The cells of the
102
BOTANICAL GAZETTE
[FEBRUARY
spongy parenchyma are decidedly more irregular in rosette leaves,
and the tissue contains a maximum of air spaces. Palisade tis-
sue is least developed in basal stem and rosette leaves, as well as
in the basal region of the leaves themselves.
Chrysanthemum Leucanthemum. — The outer epidermal wall
and cuticle of the upper and middle stem leaves are very much
alike in thickness, but both are decidedly thicker than the corre-
sponding epidermal wall and cuticle of the basal stem leaves,
the latter being only about one-half as thick. Rosette leaves do
not differ much from each other in the thickness of epidermal
wall and cuticle, but the maximum thickness may probably be
found in the middle leaf. Rosette leaves, as a whole, have a
thinner epidermal wall and cuticle than stem leaves, being only
*
one-half to two- thirds as thick. The palisade tissue is better
developed, as a whole, in stem than in rosette leaves, and decidedly
better developed in both stem and rosette leaves in apical and
middle leaves than in basal leaves. The spongy parenchyma is
slightly better developed in rosette leaves and in both kinds of
■
basal leaves. Here is found also the maximum development of air
spaces.
Oenothera biennis.- — The stem leaves are thickest in the apical
region and gradually become thinner toward the base. There is
also a gradual increase in thickness from the apical to the basal
stem leaves. The upper rosette leaves are thickest in the apical
region and become thin toward the base of the leaf. In the middle
and lower rosette leaves the greatest thickness is found in the
middle region. From this region they gradually become thinner
toward both the apex and base of the leaf.
The spongy parenchyma in stem leaves gradually diminishes
from the apical to the basal region of the leaf, but there is a gradual
increase in amount from the apical to the basal leaves. In the
upper rosette leaves the spongy parenchyma also gradually de-
creases from the apex of the leaf to the, base. In the middle and
lower rosette leaves, however, the greatest percentage of spongy
tissue is found in the apical and basal regions. In stem leaves the
palisade tissue is most developed in the apical region and least in
the basal region. The maximum development is probably found
1917]
STOBER— WINTER AND SUMMER LEAVES
103
in the apical and middle regions of the basal leaves. The palisade
cells of rosette leaves are decidedly broader or thicker than those
in stem leaves, but are relatively slightly longer. The maximum
development is found in the apical and middle regions of the leaf,
or in those parts of the leaves having the greatest exposure to light
and other desiccating influences.
The largest epidermal cells are found in the middle region of both
stem and rosette leaves. It is also in the middle of leaves that
both upper and lower epidermal cells have the greatest vertical
diameter. The outer epidermal wall and cuticle of stem leaves
are thickest in the apical leaves, and gradually become thinner
toward the basal leaves. In the upper stem leaves the outer
wall and cuticle diminish from the apical to the basal region. In
the middle and basal stem leaves there is less difference, and in the
lowest leaves there is practically no difference in thickness of the
epidermal wall and cuticle in different regions. In the upper stem
-
leaves there is not much difference in the thickness of the epidermal
wall and cuticle of the upper and lower sides of the leaf; but in the
lower stem leaves the thickness is decidedly greater in the upper
than in the lower epidermis. The greatest difference in thickness
is found in the lowest leaves.
In rosette leaves the situation in thickness of epidermal wail
and cuticle is similar to that found in stem leaves. In the upper
rosette leaves, however, there is a greater difference in thickness
of wall and cuticle between the aDical and basal regions of the leaf.
The hairs on both stem
abundant on the midrib %
The
most abundant on the upper stem
diminish in number and size to the basal leaves, where they are
quite small (except on veins) and only half or even less than half,
as abundant. On the upper leaves they are longer and more
abundant on the lower than on the upper surface, and increase in
length and abundance from the apex to the base. On the middle
stem leaves they are similar in si
in number from
the
therwise the situation is similar to that
104 BOTANICAL GAZETTE [February
leaves. On rosette leaves the hairs are slightly more abundant
on the upper than on the lower surface, and gradually diminish in
size and number toward the basal leaves. On the lower side of the
basal leaves there are very few hairs except along the margin,
where they are long and abundant. The chlorenchyma contains
an abundance of needle-shaped crystals of calcium oxalate, arranged
in bundles (raphides) . These raphides are slightly more abundant
iu rosette than in stem leaves.
Verbascum Blattaria. — In this species the palisade tissue is
best developed in the floral leaflets and in the upper stem leaves.
Here the layers are well organized and compact, and the cells
reach their maximum length. In the basal stem leaves the palisade
cells vary considerably in length, some being quite long, while
others are quite short. Moreover, the layers are poorly organized.
In the middle and upper stem leaves 3 layers are well organized,
a fourth layer being only partly organized. In the basal leaves
there is no trace of a fourth layer. The thickness, or transverse
diameter of the palisade cells, also increases appreciably from the
upper to the lowest stem-leaves. In rosette leaves there is a grad-
ual increase in the size of palisade cells from the upper to the basal
leaves. In the latter the palisade tissue is poorly developed, the
cells being very irregularly and loosely arranged, and scantily
supplied with chloroplasts.
With the exception of a few hairs on the ribs of rosette leaves and
lowest stem leaves, this plant is devoid of hairs. The basal stem
leaves and rosette leaves have the largest epidermal cells, which
also have the largest vertical diameter. The upper epidermal cells
of both stem and rosette leaves always have a decidedly greater
vertical diameter than the cells of the lower epidermis.
The floral leaflets and upper stem leaves have the thickest outer
epidermal wall and cuticle. In these leaves there is very little
difference between the upper and lower epidermis. In the upper
rosette leaves we also find a thicker epidermal wall and cuticle,
but the difference is less pronounced than in stem leaves.
A summary of the comparative study of the upper, middle,
and lower stem leaves and the corresponding upper, middle,
and lower rosette leaves, based upon the 5 species just considered,
»
1917I STOBER— WINTER AND SUMMER LEAVES 105
and in addition Leonurus Cardiaca and Verbascum Thapsus, is
as follows.
In general the lowest stem and rosette leaves, as well as the
basal part of all leaves, are most protected and most shaded, and
therefore have the most mesophytic structure. The leaves are
thinnest; the outer epidermal wall and cuticle are thinnest; the
palisade parenchyma is developed most poorly; and spongy
parenchyma, containing a maximum of air spaces and a minimum
of chloroplasts, is developed most highly.
The upper stem leaves are relatively xerophytic in structure.
This is especially true of the apical region of these leaves. We
frequently find the maximum thickness of leaf, maximum thick-
ness of epidermal wall and cuticle, and a maximum development of
palisade tissue, which in many instances develops almost equally
on both sides of the leaf. The middle and lower stem leaves are
almost invariably thinner than the corresponding rosette leaves.
The spongy parenchyma is better developed in rosette than in
stem leaves. This was true of 75 per cent of all sections studied.
The palisade parenchyma in stem leaves is better organized,
more compact, and the cells relatively longer and narrower as
compared with the thickness of the leaf. In rosette leaves the
layers of palisade tissue are frequently less perfectly organized,
less compact, and the cells larger. Palisade cells of rosette leaves
are decidedly broader and usually longer than those of stem leaves;
but the amount of palisade tissue and the length of the cells,
when compared with the average thickness of the leaves, are less
in rosette than in stem leaves. The absolute length of palisade
cells in the first layer is greater in rosette leaves than in correspond-
ing stem leaves in 70 per cent, in the second layer in 55 per cent,
and in the third layer in 28 per cent of all sections studied. In 30
per cent of all stem sections studied the second palisade layer was
not developed. The same was found to be the case in 29 per cent
of rosette sections studied. Likewise, the third palisade layer was
not developed in 81 per cent of all stem sections studied, or in 66
per cent of all rosette sections studied. The number of sections
considered in each case was the same (75 stem and 75 rosette sec-
tions). With the exception of the upper stem leaves, where the
io6
BOTANICAL GAZETTE
[FEBRUARY
upper and lower epidermis frequently have an outer wall of approxi-
mately equal thickness, the upper epidermis has a thicker wall than
the lower. In 93 per cent of the cases the outer epidermal wall
and cuticle of stem leaves were found to be thicker in stem than in
rosette leaves. The thickest epidermal walls are usually found in
the outer two-thirds of upper stem leaves. On the other hand,
rosette leaves have epidermal cells with the largest vertical diameter
and contain a maximum of air spaces.
Lepidium virginicum and Capsella Bursa- pastor is produce both
summer and winter rosettes. When these rosettes are compared,
it is found that summer rosettes have slightly thicker leaves
(thinner in Capsella), a thicker cuticle, and a thicker outer epider-
mal wall. The palisade parenchyma also is better developed.
There are frequently more layers, and the cells are longer and
narrower. These differences are most pronounced in Lepidium.
Summary on chlorenchyma. — Typical xerophytic leaves
have a relatively compact and well developed palisade tissue; also
a relatively small amount of spongy parenchyma with small air
spaces. The mechanical tissue is usually also better developed
than in mesophytic and shade leaves. Since rosette leaves are
usually broad, close to the ground, frequently more or less shaded,
and therefore in most respects better protected than stem leaves,
it should not be surprising if the former were found to be more
mesophytic than the latter. That this seems to be true, at least
of the forms studied, is shown by the following deductions.
1. Rosette leaves, as a rule, have a greater amount of chloren-
chyma than stem leaves. This is true of at least 80 per cent of all
plants studied.
2. Rosette leaves have a greater amount of spongy parenchyma
than stem leaves, although the percentage of the chlorenchyma
is slightly greater in the latter than in the former.
3. The percentage of air spaces in both palisade and spongy
parenchyma is also greater in rosette than in stem leaves. This
is true of about 86 per cent of all plants studied. In a considerable
number of instances, however, the differences are slight.
4. The number of palisade layers is much the same in both
kinds of leaves, but the average length of palisade cells, in at least
\
V
1917] STOBER— WINTER AND SUMMER LEAVES 107
80 per cent of the types studied, is greater in rosette than in stem
leaves. This is correlated perhaps with the greater thickness of
the chlorenchyma in the former. The thickness of palisade cells,
in at least 90 per cent of all cases, is also greater in rosette than in
stem leaves.
5. The average size of spongy parenchyma cells is also greater
in rosette than in stem leaves. This is true of about 90 per cent
of all plants studied.
6. Sclerenchyma tissue seems to be about equally well developed
in ribs and veins of both kinds of leaves. The conductive tubes
in veins of approximately equal size have a slightly larger lumen
and a wall slightly thicker in rosette than in stem leaves. The
conductive system of rosette leaves is better developed in rosette
than in stem leaves, although this rule is not without exceptions.
On the whole, therefore, it may be said that, so far as the
structure of chlorenchyma is concerned, stem leaves are more
xerophytic in structure than rosette leaves, although the latter
appear to be more xerophytic so far as the greater thickness of
epidermal wall and cuticle are concerned. In some instances the
xerophytic character of stem leaves, as compared with the rosette
leaves of the same plant, is so pronounced as to be easily detected
with the naked eye.
Conclusions
1. Hairs are most abundant in the upper stem leaves and
decrease to the basal leaves; they are also most abundant in
the upper rosette leaves and decrease to the basal leaves. In
general, however, the stem leaves are more hairy than the rosette
leaves.
2. Stomata are usually smaller, more nearly round, and more
abundant, per unit area, on stem than on rosette leaves.
3 . As a rule, the epidermal cells of rosette leaves are larger than
stem
The
shape of the cells is usually correlated with the shape of the leaf.
4. The blade of rosette leaves is thicker than that- of stem
leaves, chiefly owing to a greater development of spongy paren-
chyma. This is not true, however, of stem leaves that are long,
1
io8 BOTANICAL GAZETTE [febrtjary
narrow, and of a decidedly xerophytic form and structure as com-
pared with rosette leaves.
5. The outer epidermal wall of rosette leaves is thicker , as a
rule, than in stem leaves. The maximum thickness occurs in
middle stem and apical rosette leaves. The thickness of the
cuticle varies with the thickness of the epidermal wall, the thickest
walls having the thickest cuticle. Rosette leaves in the large
majority of instances have the thickest cuticle. The preponder-
ance of epidermal protection is in favor of rosette leaves. In stem
leaves of xerophytic form the preponderance of epidermal protec-
tion is in favor of stem leaves.
6. In a comparison of the different stem and rosette leaves of
the same plant it is obvious that the lowest stem and lowest rosette
leaves, as well as the basal part of all leaves, have the thinnest
epidermal wall, thinnest cuticle, the most poorly developed palisade
tissue, the maximum development of spongy tissue and air spaces,
and the minimum development of chloroplasts. The upper stem
leaves are relatively xerophytic in structure, especially in the
apical region of these leaves. The middle and lower stem leaves
are usually thinner than the corresponding rosette leaves. The
palisade parenchyma in stem leaves usually is better organized,
more compact, and the cells relatively longer and narrower, as
compared with the thickness of the leaf, than in rosette leaves.
The thickness of palisade cells of rosette leaves is greater, in most
cases, than in stem leaves. This is also true of the absolute length
in the great majority of instances.
7. When the chlorenchyma in middle stem and middle rosette
leaves is compared we may conclude: (1) that rosette leaves, in
most cases, have a greater amount of chlorenchyma than stem
leaves (this is especially true of spongy parenchyma) ; (2) that in
most cases rosette leaves also have more air spaces than stem
1
leaves; (3) that there is little difference in the number of palisade
layers in the two kinds of leaves, but in most cases the absolute
size of the palisade cells (length and thickness) is greater in rosette
than in stem leaves ; (4) that the average size of cells of the spongy
parenchyma is also greater in rosette than in stem leaves; (5) that
sclerenchyma tissue is about equally developed in both kinds of
f
1917]
STOBER— WINTER AND SUMMER LEAVES
109
leaves, but the conductive tissue is slightly better developed in
rosette than in stem leaves.
On tfre whole, typical rosette leaves, where there is consider-
able shading and protection, are decidedly more mesophytic than
stem leaves. In winter leaves on stolons or runners there is a
tendency toward greater xerophytism than in stem leaves, but
on the whole the rosette leaves are more mesophytic in structure
than stem leaves.
•
f
In conclusion, I desire to acknowledge my indebtedness to
Dr. H. C. Cowles and Dr. J. M. Coulter for helpful suggestions
and advice in this work.
Allbright College
Myerstown, Pa.
*
IMPERFECTION OF POLLEN AND MUTABILITY IN
THE GENUS ROSA*
Ruth D . Cole
During the winter
(with plates iv-vi)
of 1915-1916 I made a study of all the
hich specimens
6
This was done in connection with work on other genera of the family
Rosaceae, notably on Rubus and on Crataegus; and it has been
interesting to note that in all 3 genera there is indication of a large
amount of hybridism, and that the multiplication of species is
startlingly great.
From the Arnold Arboretum of Harvard
I have
been able to obtain flower buds of 32 different species of Rosa.
sissima, 3 of R. rugosa, and 2 of R. virginiana.
taken when on the point of opening, thus ma
spino
buds
maturity
tking sure of the
They were then preserved in alcohol until
time as it was possible to examine them
I prepared sections of about half of the species gathered, with
iew to determining how many showed sound pollen and how
many
imDer
parts.
set pollen. For this purpose the buds were first imbedded
>idin to make sure that there would be no shrinkage of the
Sections were cut with the microtome, stained with Heiden-
haematoxylin and safranin, and finally mounted in balsam.
' nearly a century it has been known that one of the most
important and most
is imDerfect Dollen.
>erfect pollen. Dutrochet 1 in 1832 recognized the morpho-
logical sterility of the hybrid and pointed out that pollen abortion
is a criterion for hybridism. Gaertner, 2 in 1849, speaks of the
*Contribution from the Laboratories of Plant Morphology of Harvard University.
trochet, Henri
Gard. Mag. 8:500. 1832.
im
Pflanzenreich. Stuttgart. 1849.
Botanical Gazette, vol. 63]
[no
1 9 1 7] COLE— POLLEN OF ROSA 1 1 1
'
importance of the pollen conditions in determining the fertility of
a hybrid as follows:
Die wichtigste Theil der Befruchtungstheile der Bastarde 1st der Pollen.
Es ist nun aber zu bemerken, dass ein vollkommen normal gebildeter Pollen
sein Ovarium nicht absolut zu befruchten vermag, weil manche mit wirklich
potentem Pollen bestaubte Blumen nicht selten doch abortiren und unbefruch-
tet abfallen : obgleich in der Regel von dem Vorhandensein eines vollkommenen
Pollens bei den reinen Arten auf die Fruchtbarkeit einer Pflanze geschlossen
werden darf.
Since, therefore, imperfect pollen is a well known characteristic
of hybrids, and one of the easiest means of identifying them, it is
from an examination of the pollen of the species of Rosa that their
probable genetical status can be determined most easily. The
thin sections through the anthers, when examined microscopically,
give one a remarkably clear view of the pollen grains in all positions
in anthers in all parts of the different buds.
Gaertner is again in harmony with our modern ideas in his
observations concerning the difference between perfect and imper-
fect pollen grains, or, as he calls them, fertile and infertile; for even
a hybrid may have the means, however imperfectly developed, of
reproducing its kind. Gaertner states as follows:
Die Gestalt und Grosse der Korner des Pollens der Bastarde in der nam-
lichen Anthere ist weit mehr verschieden, als man es nach Fritzsche und
H. V. Mohl in den der reinen Arten zuweilen antrifft.
In den Antheren aller fruchtbaren Bastarde, befinden sich kleinere und
grossere Korner mit einander vermischt in verschiedenen Verhaltnissen zum
Theil ausserst kleine von verschiedenen Graden der Unformigkeit langlichte,
eingeschrumpfte, Ieere Balge, ohne fliissigen Inhalt — am deutlichsten findet
man
Aus der Grosse und Qualitat
manchen Fallen mit ziemlicher Zuverlassigkeit auf die Fruchtbarkeit oder Un-
fruchtbarkeit eines Bastards schliessen.
Die reine Farbe bezeichnet in den meisten Fallen die Potenz des Pollens.
bemerkt
wenn
off nen .
Der Inhalt des Pollens der Bastarde ist sehr verschieden und auch selbst
bei den fruchtbaren gering, meistens fehlt er aber ganzlich und der Pollen ist
dann trocken und ballt sich nicht Wenn der Pollen seine regelmassige
Gestalt und Grosse hat so enthalt er gewohnlich eine flussige olige Materie.
H2 BOTANICAL GAZETTE [February
That is, normal pollen is perfect morphologically, fully formed,
and having normal protoplasmic contents; while abnormal or
lm
the contrary, is usually shrivelled and has little or no protoplasmic
makinsr the eram auite lm
The pollen of Rosa is largely in the last named condition, imper-
fect, and therefore probably sterile to a considerable extent. Of
Arboretum
lm
slightly intermingled; that is, showing only i-io per cent bad
pollen. Seventeen show a very large percentage of imperfect
grains (about 50-100); and the remaining 20 show 10-50 per cent.
this enormous degree 01 intertill ty 01 pollen m the genus prob-
ably accounts for much of the difficulty systematists seem to have
encountered in establishing species. Engler and Praxtl 3 speak
of the genus thus:
. Die allbekannte, von Dichtern aller Kulturvolker gepriesene Rose bildet
eine scharf umgrenzte Gattung, die sich durch den Bau der Blutenachse den
Sanginsorbeae und Pomoideae, durch den iibrigen Bliitenbau den Potentilleae
durch die Tracht insbesondere der Gattung Rubus anschliesst. Sie ist fast
uber die ganze nordliche gemassigte Zone verbreitet, geht auch in die Gebirge
der Tropen liber, fehlt jedoch auf der Suedl. Halbkugel.
Die Zahl der Arten kann man bei mittelweiter Fassung des Artbegriffes
auf etwa 100 ausschlagen, doch sind schon allein aus Europa mehrere hundert
Arten niederen Ranges beschrieben worden.
The last edition of Gray's Manual recognizes 15 species of wild
roses of the eastern United States and Canada, and in the last
edition of Field, forest , and garden botany, in which are included
cultivated species and varieties, there are 24 species. 4 Nine of the
wild species, so-called, of Gray (M.), I have been able to obtain
from the Arnold Arboretum, also 4 of the cultivated species. The
20 odd species remaining that I have analyzed are importations,
hybrids, etc., grown specially in the Arboretum. Of the 3 divisions
made of the species of Rosa according to the percentage of bad pollen
present, I shall first take up the group in which the proportion was
3 Die natiirlichen Pflanzenfamilien (p. 46).
and
garden botany by (F.F.G.).
»
i9i 7] COLE— POLLEN OF ROSA 113
less than 10. In this group are R. rugosa, R. cinnamomea, R. Kelleri,
R. pendulina, and 7?. Moyesii.
R. rugosa (figs. 5, 13) has almost no imperfect grains as may be
seen in the figures, practically all of the grains being perfectly
formed and full of protoplasmic contents. Fig. 5 shows the pollen
y teazed out of the anthers on to a slide. Fig. 13 is a cross-section
through an anther, showing the pollen grains in their normal posi-
tions in the loculus of the anther. It is worth while to note also the
generous quantity of pollen in the single loculus. Gray (F.F.G.)
\ groups R. rugosa among the principal types of exotic garden roses
mixed
??
com
instance, with R. rubiginosa (fig. 6) is its geographical seclusion
on the islands of Japan. The varieties of R. rugosa show evidence
of contamination, as will be shown later.
R. cinnamomea and the 3 other species in this group (R. Keller i,
R. pendulina, and R. Moyesii) have not been figured. All may be
found in the Arnold Arboretum. They are all practically without
imperfect pollen grains, R. pendulina comes from the mountains
of Europe, and R. Moyesii comes from China.
In the second and much larger group the percentage of imperfect
pollen is 10-50. In this group are R. spinosissima altaica, R.
spinosissima (garden variety hybrid), R. spinosissima, and R.
spinosissima hispida; also R. spinosissima paniculata (garden
variety). R. spinosissima fulgens (garden variety), because of
its larger percentage of undeveloped grains, belongs to the third
and last group. With these are R. Harrisoni (garden hybrid), i?.
gymnocarpa, R. Manetti (garden hybrid), R. blanda, R. seraphini,
R. ^ichuriana, R. no. 306 Wilson, R. pratincola, R. multijlora, R.
( davurica, R. acicularis, R. hemispherica, and R. ferruginea. Of R.
_ rugosa alba and R. virginiana alba, which properly belong in this
group, I shall speak later in connection with other varieties of th<
same species in the third group.
R. spinosissima and its 5 varieties present some very interesting
conditions. Fig. 12 is a cross-section of the typical anther of the
, so-called species. It is very clearly seen that about 40 per cent of
! the trains in the Iriniln* are shrivelled and without DrotonlasniiC
*
114 BOTANICAL GAZETTE [February
contents; and the contrast between these and the perfect grains
is very marked.
In comparing the species R. spinosissima with the recog-
nized garden hybrid, a variety of the species and called R. spinosis-
sima garden variety hybrid (fig. 10), the latter shows less pollen
in the loculus, but about the same percentage of shrivelled grains.
R. spinosissima paniculata, another garden variety, has only about
10 per cent of its pollen grains undeveloped; while still a third
garden variety, R. spinosissima Jul gens , has a larger percentage than
any of the group I have examined. This last, as may be seen in
fig. ii, has an abundance of pollen grains in the loculus, but about
50 per cent of them appear as tiny, shrivelled cells.
The two remaining varieties of R. spinosissima, R. spinosissima
altaica and R. spinosissima hispida, are apparently the least con-
*
taminated of the varieties. The first, a Siberian rose (fig. 8), has a
considerable amount of pollen in the loculus, and only about 10
per cent of its grains are bad. The second (fig. 9) presents an
almost identical situation; and this is a European variety of the
same
Harrisoni
hybrid .
typ
being im
entirely shrivelled. Gray (F.F.G.) described "R. Eglanteria L.
a yellow Eglantine rose. Like a sweetbriar, but lower. Austrian
briar, Persian vellow, and Harrison's vellow are forms of this."
specimens
exam
hybridism
developed pollen usually accepted as indicatin
Manetti, another garden hybrid (fig. 17), presents a condition
;ous to that found in R. Harrisoni. R. gymnocarpa, a north-
n North American rose, is much less contaminated than the
ro, only about 20 per cent of its pollen grains being imperfect.
e remaining species of the group under discussion present
ions more or less similar to those already described. R.
phini has
numerous
1 9 1 7l COLE— POLLEN OF ROSA 1 1 5
R. no. 306 Wilson, a Chinese wild rose, shows about 15 per cent
bad pollen; R. pratincola has about 25 per cent of its pollen grains
undeveloped; R. multiflora has about 20 per cent bad pollen. The
last is a rose native to Japan and China, and cultivated here.
Gray (F.F.G.) records it among the principal types of exotic
p garden roses: "R. multiflora Thunb. from Japan and China.
Hardy in the Middle States, a double form of an old garden rose,
1 the single form not common. Polyantha roses are offshoots of
this chiefly through hybridization with R. indica"
R. davurica is a Siberian rose which shows more imperfection of
pollen than R. spinosissima altaica, having 25-30 per cent of its
pollen undeveloped, in contrast with 10 per cent in the other
species. R. acicularis, another rose native to Siberia, is in a
similar condition of probable contamination; this species is now
wild in the Northern Hemisphere- R. hemispherica is a Persian
yellow rose, probably like R. Harrisoni, an offspring of R. Eglanleria.
I I examined the variety R. hemispherica plena, and found the pollen
I in bad condition. The last of the species in the group is R. fer-
** ruginea. native to the mountains of central Europe, and here also
the pollen was to a large extent abortive, a condition interesting
when compared with that found in R. pendulina, likewise a native
of the European mountains, but almost without bad pollen.
In the third group are those species with 50-100 per cent bad
pollen. This group is not quite as large as the second group, but
presents conditions even more interesting. It includes R. kam-
chatica, R. cordifolia, R. rugosa plena, R. rugosa alba, i?. rugosa
arnoldiana, R. oxyodon, i?. rubiginosa, R. setipoda, R. mollis, R.
macrophylla, R. canina biserrata, R. arvensis, R. gallica, R, alba,
R. damascena, R. virginiana plena, and R. Virginian a alba.
Since the conditions as they appear in the species R. rugosa have
I already been shown, I shall first take up its 3 varieties. R. rugosa
*
plena has every appearance of a typical hybrid, as evidenced by a
large degree of sterility in its pollen (tig. 14). It seems clear that
about 90 per cent of the pollen is abnormal; and the contamination
is still more marked when we compare it with R. rugosa (fig. 13).
R. rugosa alba (fig. 15) is not in such bad condition as R. rugosa
plena, for in this case only about 40 per cent of the grains are
Il8 BOTANICAL GAZETTE [February
Three species of this last group remain to be mentioned. R. seti-
gera shows a large percentage of microsporic degeneracy. R. virgini-
ana plena with about 90 per cent of its pollen bad, and R. virginiana
alba with but 25 per cent of its pollen imperfect, are varieties
of the R. virginiana Mill, of Gray's Manual. The latter, known
sometimes as R. lucida Ehrh., is a dwarf wild rose found on the
margins of swamps and rocky shores from Newfoundland and
eastern Quebec to New York and eastern Pennsylvania.
The preceding statistics show clearly that the species of Rosa are
in a very marked degree characterized by abnormal pollen. It is
true likewise that abnormal pollen is largely sterile. Pollen sterility
for nearly a hundred years has been recognized by plant breeders
prominent
Lybrids; and another well known
extreme variabilitv. Since both
extreme pollen sterility and variability are prominent
of hybrids, the conclusion seems inevitable that most of the so-called
species of Rosa are in reality hybrids.
This conclusion is most interesting when viewed from an evo-
lutionary standpoint. Are new species the result of gradual
changes or sudden leaps? The answer to this depends largely
upon the definition of the term species. In the lower vascular
plants the conditions of spore abortion and hybridization appear
to be very rare. The term species in these cases, therefore, is
used to distinguish groups of plants wholly distinct from one
another and probably genetically pure. Jeffrey 6 has shown by
microscopical investigation that morphologically sterile pollen
does not occur in plants that are monotypic, isolated geographically
or through the time of flower maturity. He has likewise made a
comparison of the "conditions of sporogeny found in the lower
gymnosperms
enormous m
;enic features of the angiosperms in which multiplication o
5 has run riot." In this comparison he found that in tin
forms of Embryophyta, from the Bryophyta to the gymno
sperms, "
ism
6 Jeffrey, E. C, Some fundamental morphological objections to the mutation
theory of DeVries. Amer. Nat. 49:5-21. figs. 7. 1915.
*
r
191 7] COLE— POLLEN OF ROSA 119
absence." Among the gymnosperms he examined Cycadales,
Ginkgoales, Coniferales, and Gnetales, and found "a single species
of Abies with evidence of abortive pollen grains of hybrid origin."
The photomicrographs of Lycopodium complanatum and Pin us
divaricata (figs, i, 2) show clearly the morphological condition typi-
cal in both genera, fertile spores uncontaminated by any abnormal,
sterile grains. Jeffrey states that "the genus Pinus is very old
and its species accordingly very distinct"; and he has not yet
found "the slightest evidence of hybridization here or in other
numerous and widely distributed species of conifers, other than the
Abies mentioned above."
In the angiosperms, on the contrary, hybridism as a condition
widespread in nature is commonly recognized. For example, in this
country and in Europe systematic botanists agree that hybridism
is extremely common as a natural condition in certain genera of
the Rosaceae. Brainerd has shown that a great many "natural
hybrids" of Rosa and Rubus, occur; and Jeffrey 7 in a recent
article says as follows :
Not only are certain of the Rosaceae recognizable as hybrids on account
f of their transitional external features of organization, Mendelian phenomena,
J etc., but certain others which have not revealed themselves as hybrids in these
J ways are clearly such as a result of a study of their spores Taking
j morphological features into account, as well as the data of the systematic
J botanists, there are three kinds of individuals; pure species, recognized species
I with pollen showing they are concealed hybrids or crypthybrids, and recog-
I nized hybrids or phenhybrids.
! These 3 classes, typical of many angiospermous genera, make
it difficult to determine
form a species
therefore, the term
from that in which
lower vascular plants. Clearly crypthybrids should not be species
same
morphologically normal genera. But they are generally admitted
by the systematist as good species because of their relative con-
stancy and the absence of observed intergrading types, though
the morphological conditions are undoubtedly those of hybrids.
7 Jeffrey, E. C, Spore conditions in hybrids and the mutation hypothesis of
DeVries. Bot. Gaz. 58:322-336. pis. 22-25. 1914.
120 BOTANICAL GAZETTE [February
Now if crypthybrids could justly be called true species, it might
possibly be admitted that they to some extent support the muta-
tion theory of DeVries. But unfortunately they are frequently,
although not universally, very variable, and this variability would
appear on morphological grounds to be the result of hybridization.
On the other hand, the natural hybrid or phenhybrid found in
the angiosperms and resulting from a cross between distinct species,
with no segregation as in Mendelian crosses, but a blending of the
parent characters, may breed true to these respective characters,
in which case a new and distinctive form is perpetuated, and to this
the systematist may justly give a specific rank. Such forms, how-
ever, are usually characterized by a large amount of sterile pollen,
unlike the true species in which the pollen is morphologically perfect.
Hence the term species is used here in a sense somewhat different
from that ordinarily implied.
In proportion to the extension of the term species, the number
of species has grown astonishingly. This multiplication of species
is probably largely due to hybridization, judging from the morpho-
logical data afforded by the Rosaceae; and generally the new
a : 99
species are crypthybrids. Hoar 8 of this laboratory has been
investigating Rubus and has reached results corresponding to those
recorded here with regard to Rosa. Hybridism appears to be even
more rife in Crataegus, and the multiplication of species is likewise
greater, as is shown by the result of work carried on by Miss Lora
Standish. 9
many of t
Arboretum
and how many are true species and phenhybrids. Take the 3
groups as presented according to their pollen sterility. To the
first group only can the term species be accurately applied, that is,
in the strict sense of the word as used of species of Pinus and
Lycopodium; for only in this group is the percentage of sterile
members may
some
8 Hoar, C. S., Sterility as the result of hybridization and the condition of the
pollen in Rubus. Bot. Gaz. 62:370-388. 1916. x
9 Standish, Lora, What is happening to the hawthorns? Jour. Heredity
7: 266-279. 1916.
19 1 7l COLE—POLLEN OF ROSA 121
In the second group there are 3 phenhybrids and 3 garden
varieties probably of hybrid origin though not so designated. The
remaining 14 are crypthybrids, several of which are treated as
species in standard systematic works; as for example, R. blanda
with 20 per cent of its pollen grains abortive, and R. rubiginosa with
f pollen almost completely undeveloped.
In the third and last group I find 3 phenhybrids; one natural
hybrid of known parentage, R. alba; two recognized hybrids,
R. rubiginosa regarded as derived from R. canina, and R. damascena
which is allied to R. centifolia and parent with R. indica of "hybrid
perpetual roses"; and two garden varieties of R. rugosa which are
also of recognized hybrid origin. The remaining 12 of this group
are crypthybrids.
• These crypthybrids of Rosa are particularly interesting in con-
nection with the several theories of the origin of species. We
know that they are common not only in the Rosaceae, but, as has
been shown to be probable, also in the Onagraceae and other
families of the angiosperms. Such forms, though recognized
I* as species, obviously cannot rank with pure species in the sense in
which that term is applied to gymnosperms, etc., in evolutionary
discussions; for, as Jeffrey has recently stated (see footnote 6),
"The conduct of such forms is conditioned more or less by their
mixed blood."
In this connection it is interesting to note the conditions pre-
sented by Oenothera Lamarckiana and other species of the genus
as described by DeVries and other authors. Here we have, as is
the case in Rosa, a considerable degree of variability accompanied
by a large amount of pollen sterility. Upon Oenothera and forms
manifesting similar peculiarities DeVries has mainly based his
mutation hypothesis.
To go back to the original question, are new species the result
of gradual changes or sudden leaps ? The Darwinian hypothesis,
as has been pointed out, is in large measure supported by the
species of Pinus. But, as I have shown, the term species when
used of Pinus has an altogether different significance from that
which it has when used of Rosa; and consequently, the problem of
evolution as presented by the species of Rosa must be an entire ly
f
•
122 BOTAMCAL GAZETTE [February
different one. There must be careful distinctions made between the
3 classes of individuals; and the search for the true solution of the
problem of the origin of species becomes thereby a matter of great
complexity. As for the mutation hypothesis of DeVries, the
morphological and systematic evidence set forth with regard to
the conditions in Rosa, and the similar conditions brought out
with regard to Rubus, Crataegus, and the Rosaceae as a whole,
seem to lend it little support, since the mutability here is obviously
the result of hybridization in nature.
Conclusions
i. The species of Rosa are characterized by a large amount of
abortive pollen and also by great variability.
2. Both pollen sterility and variability have long been recog-
nized as two main characteristics of hybrids.
3. The species of Rosa, therefore, are largely of hybrid origin.
4. On account of the great number of crypthybrids and phen-
hybrids in angiosperms, the term species has a very different
meaning from that which it has when applied to the lower vascular
plants and the gymnosperms.
5. The mutability of the species of Rosa cannot properly be
used in support of the mutation hypothesis, since this phenomenon
is obviously the result of hybrid contamination in nature.
In conclusion the writer wishes to express her most sincere
thanks to the Director of the Arnold Arboretum for permission to
collect material; and to Professor E. C. Jeffrey for advice and
assistance.
)
Harvard University
EXPLANATION OF PLATES IV-VI
PLATE IV
Figs. 1-6. — Pollen.
Fig. 1 . — Lycopodium complanatum; X 1 2 5 .
Fig. 2. — Pinus divaricata; X125.
Fig. 3. — Rosa alba; X250.
Fig. 4. — Rosa alba; X375.
Fig. 5. — Rosa rugosa; X250.
Fig. 6. — Rosa rubiginosa; X375.
BOTAXR AL GAZETTE, LXIII
PLATE IV
1
2
W
3
4
5
6
COLE on ROSA
BOTASIi. M. GAZETTE, /.Mil
PLATE V
r
•
^>
p •
v
*
7
8
i
5 *W V /CD
9
10
*
11
12
COLE on ROSA
BOTANICAL GAZETTE, LXIII
PLATE VI
13
14
15
16
I
*
17
18
COLE on RO \
«*
*
1917]
COLE— POLLEN OF ROSA
123
PLATE V
Figs. 7-18. — Transverse sections of anther.
Fig. 7
Fig. 8
Fig.
9
Fig. 10
Fig. 11
Fig. 12
Rosa oxyodon; X125.
-Rosa spinosissima altaica; X 1 2 5 .
Rosa spinosissima hispida; X 1 2 5 .
Rosa spinosissima (gard. var. hyb.); X125
Rosa spinosissima fulgens; X 1 2 5 .
Rosa spinosissima; X125.
1
Fig. 16.
Fig. 17.
PLATE VI
Fig. 13. — Rosa rugosa; X125.
Fig. 14. — Rosa rugosa plena; X125.
Fig. 15. — Rosa rugosa alba; X125. .
Rosa kamchatica; X250.
Rosa Manetti; X125.
Fig. 18. — Rosa Harrisoni; X125.
MORPHOLOGY OF KETELEERIA FORTUNEI
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 225
A. H. Hutchinson
(WITH PLATES VII AND VIII AND THREE FIGURES)
Since its discovery by Fortune, Keteleeria has aroused interest
as an endemic Chinese conifer. It was found first near the temple
of Foo Chow Foo, and reports of recent explorers locate it near
ancient shrines. Whether Keteleeria, as seems most probable in
the case of Ginkgo, was a sacred tree and has been preserved by a
religious order is a matter of conjecture.
Because of limited knowledge, even of the gross structure and
characteristics, it is not surprising that the form now known as
Keteleeria has been variously placed by systematists. Lindley
named this form Abies jezoensis, mistaking it for a Japanese
species of that name (14). Murray, in 1862, showed that the
form in question differed from A bies jezoensis and called it A bies
Fortunei after the original discoverer. In 1868 Carriere made a
new genus Keteleeria, naming it after Keteleer, a Belgian horti-
culturist. Parlatore placed the same form under the genus
Finns, as P. Fortunei; by Bentham and Hooker it was classified
with Tsuga; Bentham and Masters again placed it in the genus
Abies; while by Engler it is described under Abies.
Carriere's reasons for making a new genus were that the
form in question differs from Picea, since it has erect cones; it
cannot be included with Abies because the cone scales are persistent;
and at the same time, in habit and general aspect it resembles
Podocarpus. Further, Pirotta (14) states that a new genus is
justified because of the arrangement of the staminate strobili
("fiori maschili ,? ). The bud of the staminate strobili is borne
either in the axils of the leaves of the preceding year or at the apex
of a branch. Pirotta regards the cone clusters as true " inflores-
cences." Each " inflorescence " consists of a short peduncle
dilated at the apex into a receptacle-like body which is invested
Botanical Gazette, vol. 63]
[124
'
1917] HUTCHINSON— KETELEERIA 125
by scales; the lower scales are short, those above becoming increas-
ingly longer. The " flowers" are situated on the margin of the
dilated peduncle in the form of a circle or false crown, one or two
"flowers" being situated near the center of the receptacle. The
number of staminate cones in a cluster ranges from 6 to 10. It is
rather remarkable that the other genus of Abietineae (Pseudolarix)
which shows such an arrangement of staminate cones is also an
endemic of China. Pirotta regards this character of sufficient
importance to warrant the division of Abietineae into the Eua-
bietineae, including those forms whose staminate strobili are
single (Abies, Picea, Pseudotsuga, Tsuga), and the Pseudoabie-
tineae, including those forms whose staminate strobili are in
clusters (Keteleeria and Pseudolarix) .
Pirotta (15) has examined also the anatomical structure of
the root, stem, and leaves. The root is characterized by a primary
axial resin canal, by secondary canals arranged irregularly in the
secondary wood, and by the presence of resin-bearing "idioblasts
in the secondary cortex. In the branches there are resin canals
and mucilage-bearing "idioblasts" in the primary cortex only.
The leaves are bilateral and contain 2 marginal resin canals and
also mucilage "idioblasts" in the mesophyll.
The vascular anatomy has been studied also by Holden (ii),
who says "Keteleeria has the wood structure of Abies. Ray
tracheids are entirely absent even in such primitive structures as
•'
the first annular ring, cone-bearing branches, cone axis, and are
not recalled after wounding, although there is an abundant forma-
tion of traumatic resin canals."
Radais (17) has classified conifers according to the distribution
of the resin ducts ("caneau secreteurs") in the megasporophylls.
Upon this basis Keteleeria is placed with Cedriis and Picea, cross-
sections of the sporophyll, about the middle of the seed, showing
a
in
Pseudotsuga, and Abies the}' are situated in the inner parenchyma;
and in Pin us, in the outer parenchyma only. This classification,
according to the admission of the author, is "surtout artiiiciel."
The anatomy of the staminate strobilus has been described
• Aase (i). The general tendency in the evolution of conifers
•
126 BOTANICAL GAZETTE [February
from
scale is noted; in the first group the bract and scale are separate
almost to the base of the appendages, and both are about equally
prominent. To this group belong Keteleeria, Pseudotsuga, species
of Abies, and species of Larix.
M
multiplication of the cells in the
male gametophyte follows the sequence characteristic of the
Abietineae.
primary
and second the 2 polar (" prothallial ") cells are cut off, the third
resulting in the formation of the antheridial cell and the tube
nucleus (figs. 1-5). This stage is the most advanced found in
available material, and is believed to be the stage at which the
pollen is shed. With respect to the development of the male
to
time
emble
with others whose nuclei and cells are unequal and differently
placed indicates that the degree of development depends upon
conditions, rather than being foreordained. When inclosed by a
wall containing little cytoplasm the nucleus soon disintegrates.
Fig. 4 shows 3 nuclei which are "prothallial" in nature; the third
under ordinary conditions would be regarded as antheridial; in
-
Pinus and might be contrasted with Abies and Picea. The
appendage-like outgrowths of the exine and the inflation of the
region between the exine and intine, caused by this growth, result
in the production of wings, such as are characteristic of the
Abietineae.
The mitoses involved in the development of the male gameto-
phyte are similar to those described for Abies and Picea (12,13).
In each of the first 3 mitoses the spindle fibers become oriented in
such a way that they surround the polar nucleus; later they radiate
from it, appearing in cross-section as tufts of fibers. This pecul-
iarity of the mitotic figure doubtless is associated with the unequal
apportionment of the cytoplasm to the resulting nuclei, an in-
equality which results in more favorable conditions for the more
centrally placed nucleus.
In Keteleeria the development of the male gametophyte is not
uniformly as described. Fig. 5 shows 4 nuclei medianly placed
and almost equal in size. The association of such gametophytes
1917] HUTCHINSON— KETELEERIA 127
this case the nucleus corresponding in origin to the tube nucleus
has taken the central position. In the struggle the nucleus which
is most centrally placed gains the ascendency, the others being
crowded to the wall.
Morphology of the ovulate strobilus.-
me
of the ovulate strobilus. — The anatomy of
jVL has been studied by Aase (i). "In Keteleeria
Fortunei one bundle originates near the base of the gap in the
strobilus cylinder and supplies the bract. It remains undivided
throughout its course. Two bundles, one from each side of the
gap, supply the scale; the two bundles soon unite, forming one
inverted bundle, that is, its xylem faces the xylem of bract."
However, in the early stages the strands connected with the 2
ovules are separate. The evidence supports the theory that the
scale with its megasporangia represents a fertile bud in the axil
of the bract.
The material studied shows that at the time the pollen is shed
the megasporangium has reached the mother-cell stage. There is
only one megaspore mother cell and it is the fourth cell from the
epidermis (fig. 9), characters which still further emphasize the
relation of Keteleeria to the Abietineae.
Sieve tubes. — The sieve tubes of Keteleeria are large, 8-10X
200-400JU, and are well differentiated. Concerning the sieve tubes
of gymnosperms, DeBary (5) states that "the oblique terminal
faces are directed toward the radial planes. Sieve plates are placed
in one or two longitudinal rows over the terminal faces and the
remainder
form
spots separated by high intervening portions. These spots are
coarsely latticed, while in the cavities of the coarse lattice the very
delicate sieve structure is seen." The appearance as seen in a
described, and this
structure
H
and
fig. 6. However, transverse and tangential sections show no
ncrs r\r Hpnrp^i'nnc in the walls of the sieve tubes. The
thicken
appearance of "delicate sieve structures' ' described for radial
, sections is caused by the presence of granular inclusions in proto-
plasmic aggregations which are situated on either side of groups
128 BOTANICAL GAZETTE [February
of perforations in the sieve tube walls. The protoplasmic masses
are connected by delicate strands which penetrate these perfora-
tions (figs. 7, 8).
The general tendency in the modification of sieve tubes from
the lower to the higher vascular plants is toward an increasingly
smaller number of sieve plates. First, there is a decrease in the
number of walls upon which the plates occur. In some ferns each
sieve tube wall contiguous with the wall of a similar cell bears
sieve plates, while in most angiosperms they occur on the terminal
walls only. Again, there is a tendency toward diminution in the
number of plates on a given surface. In ferns (5, p. 180) there are
several rows of plates, or they may be closely crowded together;
-
in Vitis there are a number of elongated plates on the oblique
septae; in cucurbits there is a single plate. In Keteleeria the
occurrence is limited to the walls seen in radial sections and the
oblique terminal walls. This is true of gymnosperms in so far as
the records are available. The plates are arranged in a single
interrupted series of groups. In this respect Keteleeria is much
more advanced than Encephalartos (5, p. 181, fig, 78); the latter
has plate groups closely distributed over the radial faces. More-
over, the plate groups are much less numerous on the radial faces
in Keteleeria than on the oblique terminal faces. This is a further
advance toward the condition in angiosperms. It seems probable
that the investigation of other forms in this respect would give
valuable evidence with reference to genetic relationships.
Embryo. — The embryo of Keteleeria is of considerable morpho-
em
meristem
1
characters heretofore unknown among gymnosperms (2, 7, 8, 9, 10).
Pirotta (16) has described the seedling.
In the embryo, as found in the mature seed, the following
regions occur: cotyledons, leaf bud, and primary root. Beginning
at the exterior, a cross-section of the root, taken near the central
region (figs. 24, 25), shows the coleorhiza, the cortex, the region of
meristematic cells and mucilage cells, and the central axis.
There is a cotyledonary tube which extends throughout approx-
imately two- thirds of the length of the embryo. The cotyledons
1917]
H U TCHINSON—KE TELEERIA
129
terminal
is about one-sixth of that of the tube. At the base the tube is in
the form of a hollow cylinder (fig. 19) above; the inner surfaces
become rectangular, then star-shaped in outline (figs. 16, 17);
finally, the 4 cotyledonary tips become separate (fig. 16).
Occasional seedlings of Abies and Finns have been described
(7> 8, 9, 10) having limited cotyledonary tubes, but no such pro-
nounced structure as occurs in Keteleeria has been recorded.
Although the material did not show the earlier stages,' it seems
evident that the situation here is similar to that existing in angio-
sperms (3, 4); that cotyledons, whether several as in Coniferales,
two as in dicotyledons, or one as in monocotyledons, are all similar
in origin; that the cotyledonary growth is, primarily, that which
results from a meristematic ring about the leaf bud, the number
of cotyledons being dependent upon the number of the loci of
increased growth. In Keteleeria the major part of cotyledonary
elongation is uniform throughout the entire ring of the growth
region.
With the exception of the central axis, the regions of the
primary root are similar to those of other conifers; in Keteleeria
this region is continuous throughout, while in other conifers
described it is broken by the meristematic region. It is evident
that such a modification in structure is due to the nature of the
meristem. Since the meristem of certain conifers, including
Keteleeria, is being described in another paper, details may be
omitted here.
The differentiation of tissues as they occur in the embryo of
the mature seed is advanced beyond the stage usual for conifers
(7, 8, 9, 10). In the primary root the first cells to become differ-
entiated are those which later become mucilage tubes (shown in
black, figs. 15-27). The cells cease to divide and become vacuolate
(fig. 11); the nucleus disintegrates; the cells are greatly elongated
by division and growth of the surrounding cells and become muci-
laginous in content. Similar cells, except that they are much
shorter, are formed in the coleorhiza. The cells of the cortex
become filled with food materials, generally in the form of starch
(fig. 12). The cells forming a hollow meristematic cylinder about
!3°
BOTANICAL GAZETTE
[FEBRUARY
the central axis divide in either of two planes (fig. 13). The first
em elements
lem, become differentiated in the cotyledons; there
are 4
in
1
V>T
Fig. i.
Transverse section of a branch showing epidermis, cork cambium,
>
cortex with resin ducts, phloem, xylem, pith, and a leaf trace.
from near
tube. Th
protoxylem
16-20).
significant
in the leat bud (stem
time there is no xylem present in the primary root
1917]
HUTCHINSON— KETELEERI A
I3i
r
The 4 meristematic regions of the cotyledonary tube, with
which the protoxylem is associated, and also the meristem of the
leaf bud, connect with the hollow meristematic cylinder of the
primary root. The central axis extends beyond this junction
point, thereby modifying the structure generally known as the
cotyledonary plate (fig. 15) (7, 8, 9, 10).
I
Fig. 2. — Mature ovulate cones
\
Summary
The following characters of the form in question warrant a
genus Keteleeria, belonging to the Abietineae.
1. Ovulate strobilus. — (1) The cones are erect (text fig. 2); (2)
the scales are persistent (text fig. 2); (3) the scale and bract are
separate nearly to their bases (text fig. 3); (4) there is a single
megaspore mother-cell (fig. 9).
132
BOTANICAL GAZETTE
[FEBRUARY
2. Staminate strobilus.
staminate
clusters on a fertile branch (text fig. 3); (2) there are 2 abaxial
microsporangia on each sporophyll; (3) the pollen is winged (figs.
1-5).
3. Male gametophyte. — The pollen is shed in the 4-celled stage,
consisting of 2 polar cells, the antheridial cell, and the tube nucleus
(figs. 2-3).
Fig. 3. — Above, megasporophylls with scale and bract separate nearly to the
base; below, fertile branches bearing groups of staminate strobili; between, 2 winged
seeds.
4. Vascular anatomy.— -(i) Resin ducts do not occur in the sec-
ondary wood except as traumatic responses (text fig. 1) (11);
(2) there are no ray tracheids nor are thev " recalled bv wound-
ing" (11).
5. Embryo.— (1) There is an extensive cotyledonary tube
(figs. 15-20); (2) a central axis extends throughout the primary
root (fig. 15).
1917] . HUTCHINSON— KETELEERIA 133
6. Leaves. — {1) The leaves are spirally arranged on ordinary
branches; (2) there are 2 very closely associated vascular strands
and 2 marginal resin ducts (15).
7. Sieve tubes. — These present single interrupted rows of plate
groups on the radial and oblique terminal faces. Paired proto-
plasmic accumulations, one on either side of each plate, are con-
. nected by strands which penetrate small perforations in the
intervening walls (figs. 6-8). The sieve tubes are more numerous
on the oblique terminal faces, an advance toward the angiosperm
condition.
8. Cotyledonary tube. — This is significant in connection with
the theories of the origin of polycotyledony.
The writer wishes to express his thanks to Professor J. M.
Coulter and Professor C. J. Chamberlain for material provided
and for advice and direction during the progress of the investigation.
University of British Columbia
LITERATURE CITED
Gaz. 60:277-313. 1915.
iporophylls of conifers. Bot.
2. Coulter, J. M., and Chamberlain, C. J., Morphology of gymnosperms.
Chicago. 1910.
3. Coulter, J. M., and Land, W. J. G., The origin of monocotyledony.
Bot. Gaz. 57:509-519. 1914
4- -, ibid. Ann. Mo. Bot. Gard. 2:175-183. 1914.
5. DeBary, A. (Bower, F. O., and Scott, D. II.), Comparative anatomy of
the phanerogams and ferns. 1884.
6. Haberlaxdt, G. (Drummoxd, M.), Physiological plant anatomy.
McMillian. 19 14.
7
mnosperms
Ann. Botany 22:689-712. pi. 35. 1908
8. . ibid. Ann. Botany 23: 189-227. pi. 15. 1909
9. -, ibid. Ann
10. , ibid. Ann
1909
11. Holden, R., Ray tracheids in the Coniferales. Bot
pis. J, 2. 1913.
Abies balsamm. Bot.
figs
13- , The male gametophyte of Pkea canadensis. Bot. Gaz. 59:287
300. pis. 15-19- fig- *• 1915-
134 BOTANICAL GAZETTE [February
Pirotta, R., Sul genere Keteleeria di Carriere (Abies For tunei Murr
Bull. Soc. Toscana Orticultura 12:1-8. 1887.
t
!g # ? Sulla struttura anatomica della Keteleeria Fortunei. Rend.
R. Acad. Lincei 6:561-565. 1890.
16. , Sulla germinazione e sulla struttura della piantina della Keteleeria
Fortunei. Ann. R. Inst. Bot. Roma 6:31-34.
Radais, Maxime, Anatomie comparee du fru
Nat. Bot. 14:165-368. 1894.
Ann. Sci.
EXPLANATION OF PLATES VII AND VIII
Figs. 1-5. — Male game tophyte; X1630.
Fig. 1. — First polar cell and second primary mitosis.
Figs. 2, 3. — Two polar cells, antheridial cell, and tube nucleus; in fig. 3
the wall which later cuts off the antheridial cell has not yet been formed; the
radiating fibers may be noted.
Fig. 4. — Three nuclei have been crowded to the wall ("prothallial cells ")>
tube nucleus is central.
Fig. 5. — Four medianly placed nuclei, alike in size and structure.
Figs. 6-8. — Sieve tubes with sieve plates; X1630.
Fig. 6. — From a longitudinal radial section.
Fig. 7. — From a longitudinal tangential section.
Fig. 8. — From a transverse section, a cell from the pith ray being shown
also .
Fig. 9. — Megasporangium showing megaspore mother-cell.
10-14
embry
Fig. 10. — Cells from meristem of cotyledon.
Fig. 11. — Cells becoming differentiated to form mucilage tubes.
Fig. 12. — A cortical cell.
Fig. 13.
Lells from meristem ot primary root.
Fig. 14. — From protoxylem of cotyledonary tube.
Figs. 15-27. — Semidiagrammatic drawings of the embryo; X40.
Fig. 15. — Longitudinal median section; attached numbers indicate region
from which accompanying transverse sections have been taken.
Figs. 16-27. — Transverse sections.
Fig. 16. — Cotyledons.
Figs. 17-20. — Cotyledonary tube, showing meristematic region and
protoxylem (black).
Fig. 20. — Cotyledonary tube and leaf bud.
Fig. 21. — Junction
tyledonary
and
Figs. 22, 23. — Cortex, region of meristem, and central axis.
Figs. 24, 25. — Showing 4 regions; coleorhiza, cortex, region of meristem,
mucilage tubes; also central axis.
Fig. 26. — Section of coleorhiza, cortex, and central axis.
Fig. 27. — Section of coleorhiza and central axis.
BOTANICAL GAZETTE, LXIII
PLATE VII
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HUTCHINSON on KETELKERIA
i
BOTANICAL GAZETTE, LXIII
PLATE VIII
* ' *
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17
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19
22
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20
23
26
21
24
HUTCHINSON on KETELKIRIA
:
4
THE POLLINATION OF VALLISNERIA SPIRALIS
Robert B. Wylie
(WITH PLATE IX AND SIX FIGURES)
Vallisneria has long been counted one of the classic examples
of cross-pollination. Living vegetatively as a submersed aquatic,
its dioecious flowers are brought together at the surface of the water
in most ingenious fashion. These highly specialized flowers present
the strongest contrasts, not only in size and structure, but in
behavior as well, and give this plant its rank as one of the climax
types with respect to floral differentiation. Specializations of
such evident advantage for cross-pollination in a form so admirably
situated for vegetative propagation seem to emphasize the impor-
tance of sexuality, or at least of seed production, in the higher
plants.
While the general method of pollination in Vallisneria is well
known, many interesting facts seem never to have been published,
and the underlying principle has not been emphasized. The
figures current in textbooks are highly generalized, and some of
them are far from accurate. The story which they are intended
to illustrate is likewise incomplete or in some cases highly distorted.
In any event, neither figure nor story has done justice to the inti-
mate history of pollen transfer in this remarkable plant.
It will be noted at once that the following account diverges
radically from that suggested by Kerner's (i) beautiful and
widely copied figure. A comparison shows that these differences
relate not only to the size and structure of the flowers, but are even
more fundamental in character. Kerner emphasizes the fact
that pollination is brought about through the contact of flowers
floating on a level water surface; there follows an outline of a
method of pollen transfer through the special agency of the surface
film of water. The general drawing (pi. IX) is based on photo-
graphs of living flowers, measurements, and camera drawings of
parts.
135J
[Botanical Gazette, vol. 63
136 BOTANICAL GAZETTE [February
The epigynous seed-bearing flowers of Vallisneria are borne
singly, each within its spathe at the end of a long scape, sometimes
over a meter in length, which anchors the floating flower to the short
upright stem at the bottom of the pond. Upon reaching the sur-
face of the water through the elongation of this axis, the spathe
opens at its outer end, but remains as a partial investment of the
ovary until the seeds are nearly mature. The 3 spoonlike sepals
soon separate, disclosing the 3 bifid stigmas which are coiled in the
center of the flower (pi. IX). These fleshy stigmas are densely
clothed with the stigmatic hairs, and their snowy whiteness con-
stitutes the most conspicuous part of the flower. Rudimentary
petals and slender staminodia are present, but as they seem func-
tionless their discussion may be deferred to a subsequent paper.
The anchoring scape usually elongates sufficiently to permit the
opening flower to assume an inclined position in the water as it is
carried to one side by wind or current. The ovary, which is
20-25 mm. long before fertilization, is usually straight until the
flower opens and has taken its position at the surface; later it
often curves considerably in response to gravity, thus bringing
the floral parts more nearly parallel with the surface of the water.
This bending of the ovary at this stage is quite marked in plants
growing in aquaria where the flowers are left undisturbed for some
time.
The exposed floral parts are waxy and consequently are not
wetted by the water, with the result that the flower comes to rest
with a portion of its weight resting on the sepals and margins of
stigmas supported by the surface film. This produces a slight
depression of the water about the flower, perhaps 15 mm. in
diameter, which is abruptly declined at its inner margin next to
the pistillate flower. This sloping surface film plays an important
part in capturing the floating staminate flowers, and later is
intimately bound up with the actual transfer ,of pollen to the
stigmas. Too much emphasis cannot be laid on the complete
dependence of this plant upon the surface film of water for its
pollination processes.
The staminate flowers are borne crowded numerously within
the globose spathe which remains short-stalked at the bottom of
1917] WYLIE—VALLISNER1A 137
the pond. A count of several of these flower masses showed an
average of over 2000 flowers packed within each spathe, the whole
group the homologue of the single pistillate flower w 7 hich is solitary
within its spathe. The staminate inflorescence resembles a large
fern sorus surrounded by an indusium. This similarity is carried
further by the striking resemblance of the slender-stalked unopen
staminate flowers to polypod fern sporangia. Massed within the
spathe these flowers are joined to the axis by slender pedicels of
varying length, so as to completely fill the space between the
stem and the spathe.
The pollen-bearing flowers are very tiny, less than 1 mm. in
diameter before opening, and are simple in structure. The floral
parts consist of 3 sepals, 2 functional stamens, and rudiments of
petals. The sepals are of unequal size and are not symmetrically
disposed; 2 are similar and stand nearly opposite; while the third
and smaller one is placed laterally between them. This reduced
sepal is the first to open. Numerous tapering and curved hairs
cover the region about the base of the stamens and are doubtless of
some importance, although their functions are not clear. The
2 stamens stand close together and have their parallel filaments
united up to a point near the anthers (pi. IX).
At maturity the tip of the spathe opens slightly and the stami-
nate flow r ers begin detaching from their slender stalks. The upper-
most are the first to be shed, and 2 or 3 days may be necessary to
empty a single spathe. These detached flowers rise slowly through
the water to the surface and there very slowly open. In this
respect Vallisneria stands in sharp contrast to the writer's (2)
observations on Elodea canadensis. In that form the staminate
flowers upon release dart to the surface and there fairly explode,
scattering their pollen on the surface of the water. In Elodea,
that the sepals of the
however, it is the free floating pollen that fun<
neria the pollen retained in the anthers has
reaching the stigmas. Svedelius (3) 'reports
detached staminate flowers of Enalus acoroides snap back upon
reaching the surface of the water, although the pollen is retained
in the anthers. In Elodea canadensis, and perhaps in Enalus, the
snap of the sepals seems to be due in part at least to the release of
138 BOTANICAL GAZETTE [February
gases imprisoned between the floral parts under water. The writer
(4) has noted elsewhere that in Elodea ioensis, which has a long-
stalked staminate flower, a bubble of gas is generally associated
with the partly opened sepals, giving extra buoyancy to the sub-
merged flowers, which tug at their anchorage like captive balloons.
No prolonged observations w r ere made on the possible perio-
dicity in the release of the staminate flowers of Vallisneria, although
doubtless there is a relation between their detachment and the
gases given off by the plant during times of brighter illumination.
On one occasion it was observed that as the sun came up from
behind a building and its direct rays fell on the spathe of the
staminate inflorescence the rate of detachment was considerably
increased for a time. In Elodea canadensis (2) there is a correla-
tion between the coming of strong light in the morning and the
rate of detachment of the staminate flowers. Svedelius reports
that the staminate flowers of Enalus acoroides are released mainly
(if not exclusively) at periods of low tide. This habit is of peculiar
significance from the fact that at high tide the pistillate flowers of
that plant are wholly submerged and pollination would be impos-
sible. No explanation of this relation was suggested in the paper.
The sepals of the staminate flower of Vallisneria completely
invest the stamens until some time after the flower reaches the
/
surface. They then slowly recurve, the smaller one being first
to open (pi. IX), and as it touches the w r ater it seems to function
in orienting the flower so that when the pair of lateral sepals open
there are formed 3 boatlike structures which engage the surface
film and float the flower. This tiny flower, with its upraised
stamens and pollen mass, is so snugly fitted to the surface film by
its 3 broad areas of contact that it is kept in equilibrium under
all ordinary circumstances. They are rarely overturned, even by
rather vigorous agitation of the water, but maintain a strict right
angle to the surface film. So slender an object as a needle if thrust
into the water among these floating flowers and slowly withdrawn
will be covered by the flowers that have been drawn up with the
film of water about the needle and may be seen standing out
radially from it on all sides. Once overthrown, however, they are
not again righted, but lie partly under water.
J
r
\
1917]
W I LIE— VA LLISNERIA
139
This definite engagement with the surface film does not hinder
the free movement of the staminate flowers on the water. In
open areas they are caught by every passing breeze and are hurried
along the surface of the water. On windy days they go scudding
by the observer like tiny flecks of foam. Where the plants grow
abundantly they often mass along the windward shores in broad
zones of snowy white (fig. 1).
The anthers dehisce before the flowers open, and the sticky pollen
from the pair of stamens of a given flower usually forms a single
pollinium (pi. IX). Even if the products of the 2 anthers form
W** .
iJ^
.
Fig. 1. — Floating staminate flowers along margin of East Okoboji Lake in north-
western Iowa; the dead fish shown near center of picture was about 8 inches long.
separate pollen masses, these lie so close together as to be prac-
tically tangential, and are never widely separated, as shown by
Kerner (i). Seen under
moderate ma
masses
;leam like <
al in form
The microspores, which are
smoo
adhesi\
rubbed
in holding the spores to the
ma tic hairs.
limited
5
by the wind,
spores to the flower, but varying considerably.
The floating staminate flowers are carried aloi
and coming within the radius of the declined surfac
pistillate flower slide into the little depression, where they are
140
BOTANICAL GAZETTE
[FEBRUARY
retained.. In this manner possibly as many as 50 stamina te flowers
may be caught in a single depression, thus forming conspicuous
white patches on the surface of the water. It is interesting to
note how successfully these areas of associated flowers hold together
even when the water is quite rough. Cowles (5) mentions these
film pockets, but gives no details other than to compare them with
those of Elodea canadensis. In this
latter form, as previously described
(2), the floating pollen grains are
caught in the depressions that are
formed about the tiny pistillate
flowers. Svedelius speaks of a sim-
ilar " capturing" of the pollen-bearing
flowers in Enalus ac oroides, but does
not attribute this to the influence of
the surface film, although obviously
the case closely parallels that of
Vallisneria.
The sepals of the innermost of
the captured stamina te flowers in
Vallisneria are of course in contact
with the margins of the pistillate
flower (fig. 2), but later arrivals are
held back as they form only a single
layer in the depression. It should
Fig. 2* — Flowers floating on
surface of water in a small aqua-
rium surrounded by black paper;
pistillate flower in center.
be noted at this time that contact between flowers on a level water
surface, such as Kerner figures, could not lead to pollen transfer, as
the pollinia are upraised over the center of the flower. But with any
slight declination of the film about the pistillate flow r er, even in quiet
water, there might be contact between the innermost pollinia
and the stigmas (fig. 2). Obviously, however, any movement
resulting in a further depression of the pistillate flower would cause
the surface film to become more abruptly declined r thus tipping
the staminate flowers more sharply inward
and thereby
2-6
flowers floating at surface of water when subjected to submergence by pulling on scape
of pistillate flower.
917]
W YLIE—VA LLISNERIA
141
>
^
making conditions more favorable for pollen transfer. The upward
movement of the water due to a passing wave might serve to
temporarily depress the floating pistillate flower weighted by its
long stalk. Should the movement be sufficient to make taut the
anchoring scape, even for an instant, the depression would become
cuplike, with the inner staminate flowers standing at right angles to
its nearly vertical walls (fig. 4).
Many of the pollen masses would
thus be forced directly into the stig-
mas, although the outer ones would
still be held back at some distance.
At a certain
stage
of depression,
however, the lateral pressure of the
water breaks the surface film above
the flow r er; the sides of the cup snap
together, roofing it over; and a con-
siderable number of staminate flowers,
with the pistillate flower, are thus
shut tightly together in a
common
bubble beneath the surface of the
water (fig.
It should be noted
com
turned the staminate flowers, and
that these are now inverted UDon the
Fig. 3. — Positions assumed with
slight tension on scape of pistillate
flower.
the
stigmatic surfaces.
photograph for fig. 5 was taken th
the
staminate
To
the right may be seen a number
that were released from the depr
the
the
again to the surface; the bubble breaks, and most of the flower^
resume their original relations at the surface of the water (fig. 6).
Examination, however, shows numerous pollen grains or even
entire staminate flowers scattered over the surface of the stigmas.
Fig. 6 shows that
grou]
floating staminate flowers,
142
BOTANICAL GAZETTE
[FEBRUARY
stigmas
released when the group was submerged, has again entered the
film pocket. This resulted from being blown into the radius of the
declined surface.
Each passing wave thus brings a shift in the position of the
flowers and furthers the wearing away of the pollinia upon the
the time that the pistillate flower is at the surface
the events outlined may
be repeated hundreds of
times with varying de-
grees of submergence.
At all times, of course,
there may be additions
to the group from the
free floating staminate
flowers.
Attention
Fig. 4. — Pistillate flower has been pulled
should be directed to
the fact that any degree
farther down in water; depression is cup-shaped, of depression is helpful,
and staminate flowers stand at right angles to the j i.i i.
verticle walls.
com
mergence
probably occurs frequently, is not necessary to adequate pollination.
When the pistillate flower is finally withdrawn into the w T ater by
the coiling of the scape, numerous pollen-bearing flowers may be
trapped in the bubble of air that forms about the retreating floral
parts as they disappear beneath the surface. As the 1
1m
5 volume of
the pollinia
more and more strongly into the stigm
Obser-
vations on isolated patches of pistillate plants show that the scapes
will coil somewhat without
the
flowers are present. At the first favorable opportunity the writer
plans to make a study of the flowering habits of marked plants
in the field to determine the length of time the flowers remain at
the surface, and the influence of pollination upon the time of their
retreat.
Despite the dioecism and complete separation of the flowers in
Vallisneria, pollination seems to take place with remarkable
/
IQI7]
W YLIE— VA LLISNERIA
143
V
•■
certainty, provided both kinds of flowers are near together in the
I
same body of water. No doubt the pollen-bearing flowers often
ride the surface of the water for considerable distances. They
will float for days, and the pollen seems to withstand desiccation
for a long time. In our laboratory aquaria the decline of micro-
spores seems to be due to the attacks of fungi, and collections from
the field often show hyphae among
the spores.
From 200 to 450 ovules line the
walls of the ovary, so that the entire
pollen output of several staminate
flowers would be necessary for fer-
tilization, even if all the spores germi-
nated. Fertilization seems to take
place with certainty, for few ovules
fail to develop into seeds. Scores of
supernumerary pollen tubes are fre-
quently seen lining
the walls or
wandering through the ovarian cham-
ber among the ovules. Many of these
meandering pollen tubes form enlarge-
ments at their distal ends similar to
those previously reported for Elodea
canadensis (2).
Fig. 5. — With further depression
the water has closed over the
flowers, now shut together in a
common bubble; out-turned bases
Turning now to KERNER'S widely of staminate flowers may be seen
Copied figure illustrating his descrip- on all sides, while pollen masses are
, : * . , lt . r T r ii- • being pressed directly into stigmas;
tion of the pollination of Valhsneria near by are ^ ^^earing
Spiralis, one is Struck by the many flowers that escaped when others
points of contrast with the foregoing were caught in the bubble (these
account. His illustration shows a
• •[•.
ved during time of exposure
pistillate flower
with long
slender
and so are blurred in picture).
ovary which, relative to the spread of the floral parts, is only about
one-third of the diameter of that in our form. The spathe invests
only the base of the ovary, whereas in ours it extends up almost to
the sepals. The wide-spreading sepals are shown as straight, while
the broad stigmas are flattened, outstanding, and raised entirely
above the surface of the water. The stigmas, as shown in the
144
BOTANICAL GAZETTE
[FEBRUARY
figure, have margins fringed with long hairs and spread much more
widely than in our plant. Finally, the whole pistillate flower in
Kerner's figure is placed in such relation to the surface of the
water that it could be sustained there only on the supposition that
it is supported by a stiff stem.
Similarly, Kerxer has figured the stamina te flower as markedly
different from ours. It is represented
as having 3 equal and symmetrically
sepals; the stamens are
figured with long filaments at right
angles and protruding beyond the
margins of the sepals. Tiny clusters
of pollen grains crown these wide-
spreading filaments, carried after the
arranged
fashion of the spar torpedo well over
the margins of the flower. Com-
pared with its companion blossom,
the staminate flower is figured as
many times larger than in our plant.
These and many other minor
points of difference suggest that
Fig. 6.— Release of tension on Kerner's account is highly general-
the scape has permitted submerged fc^j and per haps intended to convey
flowers to come again to surface; , . e . „«
pollen and some entire staminate ^ a general account of the pollina-
tion in this plant. It may only be
accidental that most of the depar-
tures from the conditions found in our plant are necessary to make
possible his proposed plan of pollen transfer. On the other hand,
it may be that the European plant is essentially different from ours
of the same name ; if so, ours should be described as another species.
That there may be considerable difference between the forms on the
two continents is further supported by Turpin's (6) figures, which
show slender stamens somewhat divergent, and
flowers may be seen on stigmas.
stigmas
very
different from those found in our form. In so far as one can
depend upon published figures, it would seem
divergent plants are included in the species
pi rati
BOTANICAL GAZETTE. LXIII
PLATE IX
i
V
I
WYUE on VALLISXERIA
I
1917] WYLIE—VALLISNERIA 145
The writer would welcome photographs, drawings, or specimens
from distant regions for purposes of comparison.
In conclusion, it seems clear that Vallisneria offers a remarkable
series of specializations mainly related to pollination at the surface
of the water. A few aquatic plants have solved the problems of
pollen transfer under water, and so may carry out their entire
life history as submersed plants. A good example is seen in Cerato-
phyllum demersum L., which is pollinated below the surface and so
may flourish at considerable depths in clear water. Neither Vallis-
neria nor Elodea shows any evidence of transition to subsurface
modes of pollination, although this would seem to be a desirable
goal for all aquatic flowering plants. On the contrary, they are
perhaps carried further and further from this possible habit by their
devices favoring pollination in air. Their specializations not only
bespeak long association with water, but also constitute a remark-
able series of adaptations to pollination at its upper limit through
the agency of the surface film.
State University of Iowa
Iowa City, Iowa
LITERATURE CITED
1. Kerner, Anton, Pflanzenleben. Leipzig. 2:129-131. 1891.
2. Wylie, Robert B., The morphology of Elodea canadensis. Bot. Gaz
37-" 1-20. 1904.
3- Svedelius, Nils, On the life history of Enalus acoroides. Ann. Roy. Bot
Gard. 2:267-297. 1904.
4- Wylie, Robert B., A long-stalked Elodea flower. Bull. Lab. Nat. Hist
State Univ. Iowa 6:43-52. 19 13.
5- Cowles, Henry C, Textbook of botany. New York. 2:838. 1911.
6. Lotsy, J. P.. Vortrage iiber botanische Stammesgeschichte. Jena. 3:642
fig- 427. 1911-
EXPLANATION OF PLATE IX
A general drawing representing a group of associated flowers as they
depression.
depressed; free floating staminate flowers outside the
TOLERANCE OF FRESH WATER BY MARINE PLANTS
AND ITS RELATION TO ADAPTATION
W. J. V. OSTERHOUT
Some effects of distilled water on r
asm
have been
the
Further investigations on this
remarkable dmerences between marine
tolerance of fresh water.
p and
the same plant, with respect to their
ese differences are interesting from
their
a physico-chemical standpoint, and significant because of
bearing on the theory of adaptation.
It is commonly supposed that most marine plants are killed
by exposure to fresh water. 2 Some instances have recently come
rapidity
violacea.
observation in which death occurs with g
example of this is furnished by Polysiph
within a minute
:n pure distilled water, many of the cells
This is clearly shown by the fact that
if they are replaced in sea water at the end of a minute they become
disorganized and never recover. This effect of distilled water is
not due to the presence of toxic substances acquired during distilla-
the
Spirogy
hairs. Moreover, the same effect is produced by water taken
directly from ponds, rivers, and springs.
On the other hand, there are species which are quite tolerant
of fresh water. Some years ago the writer 3 found marine algae
growing along the sides of a steamboat
xposed
some
They were also exposed daily to concentrated sea water and to
strong sunlight, under which they reached a relatively high tempera-
ture,
blue-
included representatives of the red,
lgae, and were associated with a
somew
1 Bot. Gaz. 55:446. 1913.
2 Cf. Pfeffer, Pflanzenphysiologie 1:415
3 Univ. Calif. Publ. Botany 2:227. 1906.
Botanical Gazette, vol. 63]
[146
i9i 7l OSTERHOUT— ADAPTATION 147
fauna. One who is inclined to attribute this remarkable tolerance
of fluctuations in salinity to a process of gradual adaptation will
meet with many difficulties.
The writer recently had an opportunity, on the island of Mount
Desert, Maine, to observe plants which are subjected to both fresh
and salt water. At the mouths of brooks, in situations between tide
marks
surprisingly
the
the
some places tide pools are found in the beds of brooks.
When the tide is out these
the
and flows in a gentle current over it. The depth of the fresh water
may be as much as 7 inches, and that of the salt water 2 or 3 feet.
The line between the two layers is sharply marked. 6 In such places
one portion of a plant may be exposed for several hours a day to
fresh water, while the remaining portion is always in salt water.
seemed
plant.
What enables these plants to survive under such unusual cir-
cumstances ? The current explanation is that they have gradually
adapted themselves to these conditions. The eel grass might be
4 As soon as the plants are covered with salt water by the rising tide, the fresh
water no longer affects them, since it flows over the surface of the salt water without
mingling much with it.
5 Among the species which endure 6 hours of fresh water alternating with 6 hours
of salt water may be mentioned the following, which were kindly identified by
Dr. W. G. Farlow: Gomontia sp., Enteromorpha intestinalis, Monostroma Blyti,
Fncus vesicidosus. Some of these species, for example E. intestinalis and M. Blyti\
endure much greater exposure to fresh water. Mr. F. S. Collins has noted that Ilea
fulvescens (Rhodora 5: 175 and 6:20; also Green algae of N.A., p. 206), Enteromorpha
tnicrococca (Torr. Bull. 18:336; also Green algae of N.A., p. 204), and Pilinia minor
(Green algae of N.A., p. 292) stand exposure to fresh water. See also Pfeffer,
Pflanzen-physiologie 1:415 and Oltmaxxs, Morph. u. Biol, der Algen 2:173-183.
( x 905.
pools
J f roT n one layer to the other without any sign of inconvenience. The boundary
between the two layers is easily made visible by stirring; water-logged vegetable
there.
pool sinks
148
BOTANICAL GAZETTE
[FEBRUARY
cited as an especially good example; its leaves are exposed alter-
nately to fresh and salt water, but its roots, being covered by mud,
are exposed to comparatively little change in salinity. The theory
of adaptation might lead us to expect that the leaves of such plants
would be much more tolerant of fresh water than the roots. This
expectation is most strikingly confirmed by experiments, which
show that the root cells of these plants are killed by fresh water in a
few minutes, while the leaf cells can stand exposure to fresh water
for several hours.
the argument must
make experiments with specimens of eel grass taken from
remote
opportunity
mouths of streams, where no
water occurs. In these plants
find the same differences between root and leaf with resp
ir ability to withstand fresh water that we find in plants gr
the mouths of streams.
We must suDDose, therefore, that characters which seem
in this case nresent from
must be ascribed to entirely diff
so true of many cases which at
Doubtless
instances of adaptation.
7
5 is much significance in the fact that leaf cells may
much longer exposure to fresh water than the roo
same
[it. One might be inclined to explain this by differ-
1 wall rather than by differences in the protoplasm,
the cell wall in the root is usually more permeable
the
that
the case here, however, for when leaf cells and root cells are placed
side by side in hypertonic sea water, they are plasmolyzed with
equal rapidity, and when replaced in ordinary sea water they recover
at the same rate; this shows that their permeability to water and
to the salts in the sea water is about the same in both cases.
Another consideration shows that the difference in the behavior
of the cells cannot be due to differences in their permeability to
water. This is the fact that death is not primarily due to absorp-
7 Experiments with other species growing at the mouths of brooks showed that
individuals which have had no opportunity for adaptation to fresh water show a
great tolerance of it.
1917] OSTERHOUT—ADAPTA TION 149
tion of water. In the process of dying the majority of cells exhibit
little or no increase in size, showing that they absorb little or no
water. Certain exceptional cells may swell and even burst, but
this is not the rule. 8 Moreover, the cells die in isotonic cane-sugar
solutions, although not as rapidly as in distilled water. 9
We must look, therefore, for another explanation of these effects.
It has been pointed out by Loeb that when death occurs in distilled
water it must be due to diffusion from the protoplasm of substances
which are necessary to its normal activity, and that doubtless the
most important of these are inorganic salts. The reason why some
protoplasm is more tolerant of distilled water may be that it parts
less readily with certain salts which are combined (chemically or
mechanically) with it.
It may also be true that the less tolerant protoplasm consists
more largely of substances (globulins or other colloids) which
undergo a change of state as soon as the concentration of salts
falls below a certain limit. In order that the cell should be intoler-
ant of distilled water the globulin (or other substance) need not
constitute a large part of the protoplasm, for it might, even in
small quantity, play an extremely important role, such as that
of a protective colloid or of a constituent of the plasma mem-
bers. These effects would be very simply explained by such an
assumption.
Laboratory of Plant Physiology
Harvard University
8 In some cases failure to swell may be due to the rigidity of the cell wall, but
certain cells which have no rigid cell wall fail to swell under these conditions.
9 This has been shown for certain animal cells by Loeb, Pfluger's Archiv 97:406.
1903.
BRIEFER ARTICLES
HENRY HAROLD WELCH PEARSON
(with portrait)
Professor H. H. W. Pearson, professor of botany in the South
African College at Cape Town, died November 3, 19 16. He was born
at Long Sutton, England, in 1870, and was educated at Cambridge,
receiving the M.A. degree in 1900 and the Sc.D. in 1907. He was
assistant curator of the Cambridge herbarium from 1898 to 1899,
and then went to the Kew
Gardens where he remained
until
1903
From Kew he
went to the South African
College, where his principal
work was done. His thor-
ough training in taxonomy
enabled him to utilize at
once the opportunity of a rich
and little studied flora, and
he made numerous contribu-
tions to the Flora of South
Africa, Flora Capensis, Philo-
sophical Transactions, Geo-
graphic Journal, Annals of
Botany, and other periodi-
cals. His researches were
not confined to taxonomy.
There were ecological papers
upon South African cycads
and morphological studies of Welwitschia and Gnetum, two genera in
which he was so deeply interested that he not only spent a great deal of
time and money, but eagerly endured the hardship of collecting material
in distant and almost inaccessible places.
In a letter dated September 8, 1916, he states that he has in press
two papers on Gnetum, and that he was to make another trip to Damara-
Botanical Gazette, vol. 63] [150
r*
)
I
1917I BRIEFER ARTICLES 151
land in January to study Welwitschia and get material for further investi-
gation. In the same letter he writes: "I don't think there is the least
chance for peace before September, 191 7. I wish I could get away from
I present occupations and take a part, but I am not encouraged by the
authorities. "
Five years ago, while studying cycads in South Africa, it was my
good fortune to become acquainted with Professor Pearson, and to be
entertained in his home. He was a vigorous, kindly man, intensely
interested in his work and enthusiastic over the botanical possibilities
of South Africa.
Mountain
me a magnificent site for a botanical garden, at that time only a dream
or a vision; but with him a vision was followed by meditation, and then
by determined effort to make his dream come true. The visions which
he saw during such strolls have materialized in the National Botanic
I Gardens at Cape Town, with an unsurpassed location, and with such a
J rapidly growing collection of plants that the place is already one of the
great gardens of the world.
! By his untimely death — he was only 46 years old— science has lost a
great botanist, but it is to be hoped that his high ideals of scientific work
will still remain to guide the botanical policies of South Africa. —
J. Chamberlain, University of
SOIL MOISTURE INDEX
Outdoor botanists in thinking of any plant are likely to associate
with it some measure of its soil moisture relation. The terms xerophy te,
mesophyte, and hydrophyte naturally come to mind, or at least the con-
that
With college students, however,
no such association of ideas is likely to occur unless special attention is
directed to the subject. This may be done by requiring the student to
examine the habitat, note the associated species, and estimate the water
requirements. Such a plan was tried the past summer at the Uni-
Mountain
For
this purpose a scale, which may be called a "soil moisture index/' proved
useful. A rule of the laboratory required that every plant studied should
be recorded with an index number, this to be criticized and perhaps
altered by the instructor.
The index numbers form a scale from 1 to 10 with the following
significance: (1) lithophytes; (2) plants of driest, sterile soil; (3) hyper-
xerophytes; (4) xerophytes; (5) xero-mesophytes; (6) mesophytes;
152
BOTANICAL GAZETTE
[FEBRUARY
(7) plants of wet meadows or moist forest; (8) marsh plants; (9) plants
partly submersed; (10) plants growing in water.
In using the index most plants will be grouped around 4, 6, 8, and 10.
This will be the case especially with students who have had little experi-
ence in field work. Later, when a finer discrimination is developed, the
intermediate numbers will be employed more often. If extreme nicety
is desired, decimals may be used. They will be satisfactory in the study
of some particular community, as a meadow or a prairie, in which the
student becomes acquainted with relative moisture requirements of a
number of species. If less accuracy is required, plus and minus signs
furnish a useful means of distinction. Thus, the elms may be called
no. 6, the red maple 6+, and the red oak 6 — . Students in desert and
arid regions will need to work out the meanings of the index figures 2
and 3. Others will probably be content with calling all xerophytes
no. 4. A plant that occurs in a number of different habitats may be
indicated by two or more numbers, as, for example, Achillaea lanulosa
There is no deep philosophical conception underlying the use of the
scale and no instrumentation is intended in connection with it. It
merely emphasizes the importance of water in the substratum and
furnishes a suitable terminology for description and a vocabulary for
thinking about soil moisture relations. It is possible that in research
work on floristics the use of this or some other suitable scale may be
found desirable. Perhaps workers in different localities might agree on
typical plants to represent the different index numbers. The scale may
well be used for a better understanding of transition areas, such as
occur between meadow and marsh or between meadow and dry grass-
land. Any piece of vegetation may be given an index number if the
indexes of its component species (previously determined in other situa-
tions) be averaged. Thus one might recognize a no. 6 meadow, a
no. 6.5 meadow, or a no. 7 meadow.
Colorado, Boulder, Colorado.
Ramaley, University of
> l
CURRENT LITERATURE
BOOK REVIEWS
Evolution
A book by Lotsy 1 is the most recent contribution to the literature of evo-
lution. The author is evidently handicapped by the intricacies of English
spelling and punctuation, for there are scores of instances of misspelled words,
incorrect punctuation, and faulty idiom. It is to be regretted that these types
of elementary error were not eliminated by the publisher, for the book-making
is otherwise excellent. Perhaps the commonest error is that of ignoring the
accepted canons of word division at the end of a line. With great frequency
monosyllabic words are divided and words are broken in the middle of a syllable.
Unfamiliarity with English idiom also leads frequently to strikingly awkward
expressions. For example, on page 29, the following meaningless sentence
occurs: "This species undoubtedly are in an uninheritable way." On page
I 120 this paragraph occurs just as quoted: "While hare and rabbit don't pair
in nature, a male hare doubtless would do so if sufficiently long isolated with
Jr female rabbits, in the absence of male rabbits on an island, as ressorts from
the experiments of Mr. Houwink, showing that the hare looses its inborn aver-
sion of a tame rabbit, if it is taken soon after birth from its mother, and sucked
by a tame rabbit foster-mother." Similar passages are frequent.
Another peculiar type of error is in the use of "e.g." and "i.e."; for the
author reverses our usage constantly. He has also invented another abbre-
viation which serves him well, using "f.i.," apparently for "for instance."
Not infrequently Dutch and German words are substituted for English, as
"bij" for "by," "unter" for "under," and "alle" for "all." Any English
writer, in an evening's work, could have edited the book into acceptable
form and it is to be regretted that some such editing was not done.
Apart from these most obvious mechanical imperfections the book is of
considerable interest, in that it serves to emphasize the importance of hybrid-
ization as a factor in evolution. The author's position, however, is an extreme
one, in that he holds hybridization to be the sole cause of variation. The
principal ideas that form the backbone of his argument are as follows.
1. Linnean species, or Linneons as he calls them, are not species at all, but
artificial groups of intercrossing types, that are constantly giving Mendelian
ratios. All so-called mutations are merely extracted recessives, which if iso-
lated produce new pure types.
1 Lotsy, J. P., Evolution by means of hybridization. 8vo. pp. viii+166. The
Hague: Martinus Nyhoff. 19 16.
153
154 BOTANICAL GAZETTE [February
2. A real species is "a group of individuals of identical constitution, unable
to form more than one kind of gametes; all monogametic individuals of identi-
cal constitution consequently belong to one species."
3. A "Linneon," says Lotsy, "is a vestigial group of a once much larger
group of differently constituted types, born of a cross, which is apt to simulate
a species by the overwhelming majority of the dominant types it contains, as
a result of free-intercrossing, combined with a favoring of the dominants by a
process of selection, weeding out the weaker or more conspicuous recessives;
this uniformity being more apparent then real, because pure dominants are
indistinctible, in most cases, from dominant-hybrids."
4. In another place the author states briefly his idea of the causal factors
of evolution. "The vera causa of the production of new types consequently
is: crossing; the vera causa of their extinction: the struggle for life; the
selection resulting from the latter is by no means a revival, but is the sign of
the struggle of the doomed." Just what is meant one can only conjecture by
the context.
In taking the position that no variations or mutations arise except as the
result of crossing and subsequent segregation, the author throws out of court
the mutants that have arisen in such carefully controlled experiments as those
of Morgan and his pupils on Drosophila. He challenges the reader to produce
a single case of mutation in a true species, which, according to him, is a type
that produces only one kind of gamete and shows no variability in Fj and F 2
generations. In other words, if a mutation does occur it may be taken as
prima facie evidence of impurity in the stock. Such an argument leads
nowhere. '
The author follows his theory to its logical conclusion and attempts to
show that even classes and orders must have been the result of crossing. We
fail to see the necessity of forcing a theory, that seems fairly reasonable when
applied within limits, to such an absurd length. If we object, we are told
that "a formation of new classes is not in action at the present moment, so
that it is illegitimate to claim that one who wants to explain evolution must
demonstrate how such a formation of new classes goes on."
In conclusion, the reviewer would like to recommend the reader to the
second edition of this book, which, if it ever appears, will doubtless be a con-
siderable improvement on the first. — H. H. Newman.
MINOR NOTICES
Forestry for boys. — In a volume dedicated to the youth of America and
manner
the problems and processes of tree growth, forest development, and forest
utilization. The extent and economic value of our forests are well emphasized
2 Moon, F. F., The book of forestry. 8vo. pp. xvii+315. figs. 64. New York:
Appleton. 1916. $1.75.
r
*
1917] CURRENT LITERATURE 155
and the importance of their conservation made clear. The harvesting and
' utilization of the timber crop is described in an interesting manner, as well as
the training and duties of the forester. Some attention is given to such forest
industries as maple sugar making, nut growing, resin production, and wood
distillation. A word is said about the value and care of shade trees, and a
glance is taken at the future possibilities of forestry, everything being treated
t in a non-technical way likely to interest the "Boy Scout" and many of his
I elders. The latter part of the book is devoted to very brief descriptions of some
50 trees, each being illustrated by a small drawing of leaves and flowers or fruit.
I While neither a textbook nor a scientific treatise, it is interesting and seems
well suited to the purpose of interesting the public and more particularly the
boys, in the forest and the forester as they concern the happiness and pros-
perity of our land. — Geo. D. Fuller.
Soil bacteriology, — A laboratory manual of soil bacteriology by Fred 3
is intended as a guide to teachers and students in courses given in soil bacte-
riology. The subject is logically developed and directions are given in clear,
concise form. There is perhaps no branch of bacteriology so intimately
associated with chemistry as soil bacteriology, and therefore considerable
I attention is given to this phase of the subject. There are a number of excellent
I illustrations in the book, and one of the most valuable features is the fairly
complete assortment of recipes for preparing culture media suitable for the
study of soil bacteria. Special sections deal with methods of quantitative and
qualitative chemical methods of analysis. Provision is made at the conclusion
. of exercises for the student to record results in tabular form, a feature which
adds materially to the value of the book-
It is being realized in agricultural schools that the study of soil bacteriology
is of eminent importance, and this manual will undoubtedly be appreciated by
those interested in such courses. — P. G. Heinemanx.
North American flora. — The first part of Vol. 21 begins the Chenopodiales
by presenting the Chenopodiaceae monographed by Standley. 4 There are
195 species recognized, distributed among 27 genera. A new genus (Meiomeria)
is based upon Cheno podium stellatum S. Wats. The large genera are A triplex
(96 species, 20 of which are new), Cheno podium (52 species, 13 of which are
new), and Dondia (20 species, 7 of which are new). New species are also
described in Salicomia (2) and Efidolepis. One of the remarkable features of
the family is the number of small genera, 13 being represented by a single
species, and 4 by 2 species. In fact, 177 of the 195 species are included in 4
of the 27 genera.
Fred
i2mo. pp. 170
Philadelphia: Saunders Co. 1916. $1.25.
4 Xorth American Flora 21: part 1. pp. 1-93. Chenopodiales: Chenopod
by P. C. Standley. New York Botanical Garden. 19 16.
156 BOTANICAL GAZETTE [February
The sixth part of Vol. 9 concludes the presentation of the Agaricaceae by
Murrill, 5 5 genera being presented, which include 165 species, 16 of which
are described as new. The largest genus is Clitocybe, with 88 species and
including 13 of the new species. The part closes with a list of corrections and
a bibliography for the volume. — J. M. C.
Jackson's glossary.— A third edition of this well known volume has
appeared. 6 The development of subjects in botany and the consequent
nology
true
a
jw edition imperative. Especially is this
recently coined terms" in ecology. No
isary
trustw
>rthy as such a book can be. It
contains approximately 21,000 terms, so that it must be fairly representative
terminology. With
ossary
J. M. C.
Correspondence of Linnaeus. — Under the editorship of Hulth, the
correspondence of Linnaeus is to be published in a series of volumes, the first
one of which has just appeared. 7 The collection includes letters "from and to"
Linnaeus. The extent of the correspondence is indicated by the fact that this
first volume, of over 400 pages, includes 49 correspondents listed under the
first two letters of the alphabet. Most of the letters are in Latin, and give an
period. — J
ology
NOTES FOR STUDENTS
Cecidiology. — Three interesting American papers on the histology of galls
have been published recently and demonstrate the increasing interest in the
study of pathogenic structures.
Stewart 8 presents a very interesting paper on the anatomy of Peri-
dermium galls. The studies were made from Peridermium cerebrum Pk. on
Piniis Banksiana Lamb. Galls of various ages were used, but all of them
from young branches. It appears that the infection usually takes place during
the first year's growth of the shoot. The woody portion of the gall was very
distinct from the normal tissue. The author summarizes his results as follows:
5 Op. ciL Agaricaceae, by W. A. Murrill. 9:375-426. 1916.
6 Jackson, Benjamin Daydon, A glossary of botanic terms, with their derivation
and accent. 8vo. pp. xii+428. Philadelphia: Lippincott. 1916. $3.00.
' Hulth, J. M., Bref och Skrifvelser af och till Carl von Likne. Vol. I.
Adanson-Brunnich. 8vo. pp. viii+429. Upsala: Akademiska Boktryckeriet.
1916.
8 Stewart, Albax, Notes on the anatomy of Peridermium galls. Amer. Jour.
Bot. 3:12-22. 1916.
f
1917] CURRENT LITERATURE 157
"(1) both an alternate and an opposite arrangement of bordered pits in the
radial walls of the tracheids; (2) an unequal thickening of the walls and
% lumina of the tracheids; (3) very short tracheids with blunt end walls, which
resemble parenchyma cells except in the pitting; (4) cells which are transi-
tional between tracheids and parenchyma cells in the pitting; (5) the presence
of true wood parenchyma cells; (6) a small production of thin- walled summer
tracheids; (7) a probable absence of bars of Sanio from many of the tracheids;
(8) an increase in the number of rays in the gall wood; (9) a tendency toward
the production of multiseriate rays; (10) ray tracheids which are transitional
between those of hard and soft pines; (11) the presence of a balled or whorled
arrangement of tracheids in the tangential sections; (12) a great increase in the
number of resin canals in the gall wood, but no such increase in the uninfected
wood close by. The examination of this gall has revealed so many points of
anatomical interest that a further study of this subject seems to be worth
while. On this account the author expects from time to time to issue other
papers on the anatomy of Peridermium galls on pines and other conifers."
It remains for someone to make a study of the very early stages of this and
many other abnormal plant growths.
Rosen 9 has made a study of the histology of the grape leaf gall. The
author has made a study of this gall from its very earliest stages to its maturity.
He summarizes his results as follows: "(1) the Phylloxera vastatrix leaf gall
P starts to develop on embryonic bud leaves; in 24 hours the insect produces
I a depression at the periphery of which hairs are formed on the upper surface of
the leaf; the depression is due to a lessened growth of the attacked mesophyll;
(2) after 3-4 days of insect attack the lower half of the leaf tissue which sur-
rounds the portion in which the proboscis is inserted has proliferated enor-
mously; the whole thickness of the leaf in the region immediately around the
proboscis shows no proliferation; that portion of the leaf which is beneath the
insect does not proliferate, but the upper half at the sides of the insect grows
and forms the walls of a large insect cavity; upper epidermal cells and several
layers of mesophyll cells in the portion of the gall below the insect show peculiar
thickening and dissolution of their cell walls; (3) gall development depends
upon leaf development; when the leaf reaches its maximum size, after 12-15
days of development, the gall becomes mature; (4) a mature gall shows but
j slight cuticular development and very few stomata; the mesophyll is a huge
mass of compact, thin-walled, partly empty cells, some of which are under-
sized, and others enormously elongated; the vascular elements are scattered
by wedges of parenchyma cells; many unicellular and multicellular hairs grow
out from the gall; (5) chemical work on this gall shows it to be a structure in
which anabolic processes are lacking, and in which large amounts of simple
sugars and simple proteins are present; (6) the development of this gall does
9 Rosen, Harry R., The development of the Phylloxera vastatrix leaf gall. Amer.
Jour. Bot. 7:337-360. 1916.
158 BOTANICAL GAZETTE [February
not seem to support the theory that the insect injects some chemical into the
leaf which causes gall formation; (7) intumescences produced by chemical
sprays result from entirely different kinds of hyperplastic responses than
hyperplastic gall growth; (8) the investigation establishes the fact that the
proboscis may pass through the entire thickness of the leaf; (9) the insect
remains fixed, and that portion of the leaf in which the proboscis is fixed is
marked by lack of growth as compared with the huge outgrowths which sur-
round it; (10) the continuous sucking action by the insect at one fixed point
for fifteen days is believed to be the initial stimulus for gall development/ '
Another very interesting paper is by Wells, 10 who has made a study of
the galls of our common American hackberry. The purpose of the paper as
stated by the author is as follows: " (1) to present a survey of the known insect
and mite galls of Celtis occidentalis L. ; (2) to elucidate the history of the normal
gall-bearing parts of the hackberry and that of the galls; (3) to study com-
paratively the structures treated, pointing out any significant conclusions and
generalizations that may be attained in such a study.' ' The author gives
excellent descriptions of the external and histological character of the galls
and concludes the paper with the following summary: "(1) there are 17 known
species of zoocecidia occurring on Celtis occidentalis, belonging to 4 orders of
arthropods (Acarinae 1, Lepidoptera 1, Hemiptera 5, Diptera 10); all are
heteroplasias, that is, those forms of hyperplasias (abnormal increase in size
through cell proliferation) whose cells and tissues differ from the normal; all,
be it noted, are built up on the basis of the same germ plasm, namely, that of
the single species of the plant mentioned; (2) the acarinous and lepidopterous
galls are kataplasmas of those forms of heteroplasias whose cells and tissues
do not vary widely from the normal; each shows specific and characteristic
inhibition of differentiation; (3) the hemipterous and dipterous galls are proso-
plasmas of those forms of heteroplasias whose cells and particularly whose
tissue forms differ fundamentally from those of the normal parts; (4) in the
prosoplasmas the types of cells found are closely comparable to those of the
normal plant parts, but the tissue forms discovered are fundamentally new;
no analogous structure forms are to be found in the tissues of the normal plant
or its allies; (5) in the dipterous prosoplasmas, since the gall's specific tissue
form characters are related to the species of insect, we have the unique case
of the 'overlapping' of the hereditary constitution of an animal on that of the
plant in the sense that factors associated with the insect determine the form
character locally, rather than those normally associated with the plant's germ
plasm; these latter plant factors suffer suppression; (6) it is suggested that in
the field of zoocecidiology we probably have a unique place, heretofore unrecog-
nized, to attack the problem pertaining to the mechanism used in the expression
of hereditary characters." The paper is well illustrated. — Mel T. Cook.
10 Wells, Bertram W., The comparative morphology of the zoocecidia of Celtis
occidentalis. Ohio Jour. Sci. 16:249-290. 1916.
p
1917] CURRENT LITERATURE 159
Transpiration studies. — Among the more recent devices for the investi-
gation of the conditions affecting transpiration is the porometer devised by
Darwin, 11 which has attracted the attention of several workers, leading to
improvements by Balls 12 and by Jones 15 resulting in self-recording instru-
ments. Knight 1 * then somewhat simplified the device, and later, assisted
by Laidlaw, 1 * produced an automatic instrument that is probably better than
its predecessors for most forms of stomatal investigations. All agree in
measuring the stomatal opening by the rate at which air passes through the
stomata with a given pressure. A rather careful study by Knight 16 of the
methods to be employed in avoiding errors in the use of the porometer is sug-
gestive to future investigators in this field. Among the interesting results
obtained by this method there may be mentioned those of Darwin, and of
Laid law and Knight, who found indications that upon severing a leaf from
a stem and allowing it to wilt, a temporary opening of the stomata immedi-
ately preceded the closure accompanying wilting.
■
In a recent investigation Trelease and Livingston 17 have made a com-
parison between the porometer and the standardized cobalt chloride paper
methods, and have obtained results showing a general agreement of data from
I the two. In the daily march of transpiring power the two are in close accord
I during the morning hours up to about 8 :oo a.m., but from that hour until 11:00
I a.m. the porometer index continues to increase, while the cobalt paper index
*i tends to decrease. After 11 :oo a.m. the influence tending to decrease becomes
evident in the porometer index also. This is taken to indicate that the poro-
meter measures the diffusive capacity of the stomata, but fails to take into
account other influences affecting foliar transpiring power. The divergence
J in the two records, therefore, may be an index of non-stomatal influences upon
transpiration. On account of the limited data, these workers are not inclined
J to press this conclusion, but it appears to be an extremely probable suggestion.
*
IX
Darwin, F., and Pertz, D. F. ML A new method of establishing the aperture
of stomata. Proc, Roy. Soc. London B 84:136-154. 191 1.
12 Balls, W. L., The stomatograph. Proc. Roy. Soc. London B 85:33-44. 1912.
13 Jones, W. N., A self-recording porometer and potometer. New Phytol. 13:
353-3 6 4- i9 I 4-
14 Knight, R. C, A convenient modification of the porometer. New Phytol.
14:212-216. 1915.
15 Laidlaw, C. G. P., and Knight, R. C, A description of a recording porometer
and a note on stomatal behavior during wilting. Ann. Botany 30:47-56. figs. 3.
1916.
16 KNIGHT, R. C, On the use of the porometer in stomatal investigation. Ann.
Botany 30:57-76. 1916.
17 Trelease, S. F., and Livingston, B. E., The daily march of transpiring power
porometer
Jour. Ecology
4:1-14. figs. 2. 1916.
160 BOTANICAL GAZETTE [February
An investigation upon a much larger scale, resulting in an abundance of *
data, is reported by Briggs and Shantz. 18 It was carried on at Akron,
Colorado, and the transpiration was determined by weighing plants potted in
sealed cans upon the automatic scales recently described by the same authors. 19
Solar radiation, wet-bulb depression, evaporation, air temperature, and wind
velocity were also measured, and the relationship between these physical factors
and transpiration was shown. The plants employed were wheat, oats, sorghum,
rye, alfalfa, and Amaranthns retrojlexus, the hourly rate throughout the entire
day being determined, the number of determinations ranging from 6 for
Amaranthus to over 40 for alfalfa. The resulting data are expressed in tables
and graphs which also serve to express their relationship with the physical
factors. Correlation coefficients and method of least squares are also used to
analyze these relationships and give some interesting results. Space permits
the citing of their final conclusion only, to the effect that their results agree
with those of other investigators that plants under conditions of high trans-
piration do not respond wholly as free evaporating systems, even if bountifully
supplied with water. It is interesting to note that none of the plants here
studied show the mid-day drop reported by Trelease and Livingston, by
Shreve, and by other observers at the Desert Laboratory.
Muenscher 20 has used the method of determining water loss by weighing
and then making counts and measurements of the number and size of the
stomata of Phaseolus, Ricinus, Zea, Primula, Impatiens, Pelargonium, Triticum,
and Helianthus. He found no constant relation between the number and
size of stomata in relation to unit area of leaf surface and the amount of trans-
piration. He also concludes that the amount of transpiration is not governed
entirely by stomatal regulation. His work, however, does not show any
explanation for any other control.
In one of the most recent publications upon this subject, by Bakke and
Livingston, 21 data are given upon the daily march of foliar transpiring power of
different leaves of plants of Xanthium and Helianthus. These serve to empha-
size the fact that the control of foliar transpiration by the plant is a complex
one, especially as there is a great range in transpiring power among the differ-
ent leaves of the same plant with considerable variation in time of the diurnal
maxima. No very definite relation is established between age of leaves and
their behavior, except that the oldest ones always show a low daily range of
18 Briggs, L. J., and Shaxtz, H. L., Hourly transpiration rate on clear days as
determined by cyclic environmental factors. Jour. Agric. Research 5:583-649. 1916.
19 j ,\ n automatic transpiration scale of large capacity for use with freely
exposed plants. Jour. Agric. Research 5:117-132. 1915.
Muenscher, W. L. C, A study of the relation of transpiration to the size and
number of stomata. Amer. Jour. Bot. 2:449-467. 1915.
21 Bakke, A. L., and Livingston, B. E., Further studies on foliar transpiring
power in plants. Physiol. Researches 2:51-71. 1916.
20
1917] CURRENT LITERATURE 161
transpiring power and usually low maximum index values. In addition to the
transpiration data, this paper contains a description of an improved apparatus
for providing a standard evaporating surface.— Geo. D. Fuller.
Fossil cycads. — The second volume of Wieland's 22 memoir on American
fossil cycads represents a large amount of additional work on material with
* structure preserved, and in particular of a new monocarpic trunk from the
Black Hills discovered by Dr. N. H. Darton. It is replete with admirable
line drawings and half-tones representing both external form and internal
structure. The material is in addition illustrated by 58 superb plates in helio-
! gravure. The whole constitutes an achievement of which American paleo-
botany may well be proud.
Although the volume is described as systematic in its contents, it con-
j tains much that is of interest to the anatomist and the evolutionist. Con-
siderable space is devoted to the anatomy of trunks of cycadeoidean forms,
and the fact that the fibrovascular tissues are much more woody than in the
I living representatives of the cycads is emphasized. This is the consequence
of the narrow rays and the sparse parenchyma, both features of contrast to the
living cycadean cylinders. The author apparently has not found in American
Mesozoic material the interesting reduplication of the central cylinder recently
described by Stopes in a publication of the British Museum. This situation is
interesting as it tends to discredit the hypothesis of Worsdell that the redu-
plication of the cylinder in cycads is a vestige of the complex system of fibro-
vascular bundles found in certain species of Medullosa, etc. The situation in
fact is comparable rather with that found in vines, and it is interesting to note
in this connection that it is not improbable that the cycadeoidean genus
Anomozamites was a climbing plant. The author emphasizes the statement
that the mucilage cavities of the cycadeoidean forms were isolated cysts and
did not constitute a system of canals as in living cycads.
Certain interesting statements are recorded in regard to the leaves, although
most of these represent only elaborations of facts already known. The leaf
trace departs from the cylinder as a large horseshoe-shaped strand which passes
directly toward the leaf base, breaking up into numerous bundles in transit.
This situation is in marked contrast to conditions in the living genera where
numerous strands take their exit from the cylinder for each leaf and pursue a
circuitous course through the cortex toward the leaf base. It is obvious that
the cycadeoidean forms, so far as their anatomy is known, were unilacunar,
that is, there was a single gap in the cylinder of the stem for each foliar supply;
while in the living Cycadales the vascular system of the leaf is multilacunar.
The cycadeoidean condition is obviously more primitive, as it is found in the
reproductive axis and occasionally in the seedling of living forms. The ana-
22 Wieland
Carnegie Inst.
Washington, Publication 34. 19 16.
l62
BOTANICAL GAZETTE
[FEBRUARY
tomical conditions in the Cycadophyta as regards the number of foliar gaps for
the vascular supply of the leaves illustrate the danger of using the number of
leaf gaps as a phylogenetic criterion, as has recently been attempted in the case
of the dicotyledons. The leaf supply of the cycadeoidean forms was dis-
tinguished from that in the petiole of existing cycads by the strong development
of secondary growth in the bundles on the upper side.
The reproductive structures are considered in some detail in the light of
additional facts. The reviewer, however, expresses a regret, which will doubt-
less be common to those interested in the evolutionary history of the seed plants,
that so little further information has been secured in regard to the crucial
apical region of the seed. The author still maintains his earlier position in
regard to the cycadeoidean origin of the angiosperms. Although he is sup-
ported in this view by a number of eminent European paleobotanists, perhaps
it is open to question whether a hypothesis which finds little valid support in
the anatomical organization of either the reproductive or vegetative structures
will in the long run prove acceptable. The Goebelian character of the author's
morphology is everywhere apparent, but most strikingly perhaps when he
ventures to compare the seed of the Pteridosperm with an angiospermous
flower. Surely this is carrying the Goebelian definition of an organ as the tool
of a function to its logical reductio ad absurdum.
The memoir under discussion contains a wealth of facts to which it is
impossible to do justice in a review. It will rank with those of Berry as a
most notable recent contribution to American mesozoic paleobotany. —
E. C. Jeffrey.
*
<
The cohesion theory. — The cohesion theory of sap ascent has received
much attention in recent years, and much supporting evidence has been
brought out;
Jost 2 3
substantiated, and that all we need to do now is to find out w r here the cohering
water columns are located. He believes much experimental work is still neces-
sary to determine whether this theory is correct. Proceeding from early
experiments of Sachs and others, and using mainly such plants as Sanchezia,
Cobaea, Biota, and Chamaecyparis, he has made a quantitative study of water
delivery by the basal portion of decapitated plants, as compared with the
transpiration need of the top before and after cutting. The principal experi-
ments attempt to determine the influence of suction upon the rate of water
delivery by the root, and to determine whether continuous negative pressures
can be maintained by a transpiring plant. As suction and pressures of only
one or two atmospheres were used, the experiments seem to the reviewer little
adapted really to test the cohesion theory; and considerable space is occupied
experiments
23 J 0S t, Ludw
Bot. 8:1-55. 1916.
Zeitschr
1917] CURRENT LITERATURE 163
will have value no doubt in preventing useless attempts along the same lines.
However, they provide Jost the opportunity to discuss the cohesion theory
and to present his own views of it.
The actual results add little that is new. He found that suction on the
root causes an increase in water delivery, especially in plants which normally
exude sap on being cut, and that greater suction causes a greater root excretion
of water than low suction. But there seems to be no proportion between
amount of suction and rate of water delivery, as should be the case if the root
acts merely as a filter in water intake. The maximum suction possible with
an air pump could never cause a delivery sufficient to cover even a moderately
estimated transpiration need. Completely surrounding the root with water,
or replacing the atmosphere about the roots with hydrogen, or excessive cooling
of the roots, leads to noticeable decrease of water delivery, even with strong
suction.
Tensions existing in the water columns of the intact plant were demon-
strated by the rapid intake of water by freshly cut tops, although the plants
previously had been kept in condition of low transpiration. Suction on the
cut end of the top, or pressure exerted upon it, produces only a temporary
decrease or increase respectively in water intake by the top. It was found
that plants could continue transpiration essentially undiminished at real
negative pressures of 15-25 cm.
Jost comes to the conclusion that, even in low plants like Cobaea, Chamae-
cyparis, etc., just as in tall trees, very considerable negative pressures must
exist, if we assume that the osmotic pull of transpiring leaves must pull in
sufficient water through a passive filter-like root.
In the concluding section he questions whether it is possible for high
negative pressures to exist continuously in the stems of plants, and proceeds
to answer the question by subjecting stem tissues to high gas pressures. In
Ficus Carica he found all the vessels easily penetrated by air, this experience
running counter to the recent work of Renner and Holle, which shows that
there may be two kinds of vessels present, storage and conducting, the latter
being more or less impermeable to air, and providing the cohering water
columns. In such a case as Ficus, Jost thinks that those who hold to the
cohesion theory must suppose either that there are no cohesion phenomena in
plants with nothing but tracheae, or that certain vessels remain with cohering
water columns by pure accident, or that in closed vessels entirely different
conditions obtain from those which have been cut. The question of unbroken
columns is vital to the cohesion theory, and those who adhere to it must expect
to be called upon to prove the existence of cohering columns of water which
can remain unbroken under the reduced or negative pressures involved in nor-
mal transpiration. The conservative view of so prominent an authority on
plant physiology will help us to maintain a balanced perspective with reference
to this important problem. — Charles A. Shull.
164 BOTANICAL GAZETTE [February
Genetical investigations of maize endosperm. — Fujll and Kuwada 24
have noted chemical differences between the red and the purple pigments of
the aleurone cells of maize, as indicated by differences in their solubility in
alcohol and in i per cent aqueous solution of sodium carbonate, and in their
color reactions with acids and alkalies. They state that the two pigments occur
either separately or together in the same seed. The latter fact, if substantiated,
should prove of interest to geneticists working with maize. The authors
suggest that variations in intensity of aleurone color may be accounted for in
part by the triploid nature of the endosperm, whereby reciprocal crosses may
differ in having either i or 2 doses of the dominant factor concerned and F 3
seeds differ in having either 1, 2, 3, or no doses. A cumulative effect of domi-
nant factors is assumed. They are apparently in error in attempting to
apply the same assumption to red color of wheat, where, so far as known
to the reviewer, the color is in the pericarp (diploid) rather than in the
endosperm.
The genetical significance of the triploid nature of maize endosperm was
earlier pointed out by Hayes and East 25 in reporting results of crosses between
races with corneous and with floury endosperm. In reciprocal crosses between
flinty and floury varieties xenia did not occur. In F 2 a 1:1 ratio was obtained
whether the F t was self-pollinated or cross-pollinated by either the flinty or
the floury parent. A half of each class of seeds resulting from self-pollination
bred true and the other half again segregated. When Fi was cross-pollinated
by the flinty parent, all the corneous seeds bred true and all the floury ones
proved to be hybrid, while the reverse was true when Fi was crossed back to
the floury parent. Two hypotheses are offered to account for the results:
(1) the endosperm develops from the fused polar nuclei without double fertil-
ization, or (2) the two polar nuclei dominate the single second male nucleus.
A plant, pure for white endosperm but hybrid for endosperm texture, polli-
nated by a pure yellow corneous seeded race, gave a 1 : 1 ratio of corneous and
floury seeds, all of which were yellow, thus demonstrating double fertilization
and indicating the second hypothesis, that two doses of a factor for floury
endosperm dominate one dose of the corneous factor and vice versa. Crosses
of popcorn with both floury and dent types gave results more difficult of
analysis, owing in part, the authors suggest, to differences in seed size, but
two independent factor-pairs are indicated in at least some of the cases. It is
also thought that two factor-pairs are concerned in the inheritance of sharp
points characteristic of rice pop-corn. — R. A. Emerson.
24 Fujn, Kexjiro, and Kuwada, Yoshinari, On the composition of factorial
formula for zygotes in the study of inheritance of seed characters of Zea mays L.,
with notes on seed pigments. Bot. Mag. (Tokyo) 30:83-88. 1916.
2 s Hayes, H. K., and East, E. M., Further experiments on inheritance in maize.
Conn. Agric. Exp. Sta. Bull. no. 188. pp. 31. pis. 8. 1915.
1917] CURRENT LITERATURE 165
Genetics of flax. — Miss Tammes 26 has made a genetical study of the flower
characters of 6 varieties of the common flax, Linum itsitatissimum. These
varieties consisted of 3 dark blue, 1 light blue, and 2 white varieties. Besides
the color of the flower, with which she worked chiefly, she studied the color of
the anthers, the color of the seeds, the shape of the petals, the color of the veins
in the petals, and the number and viability of the seeds produced. These
latter characters she finds correlated with the color of the flower and dependent
upon the same factors. The several varieties are described and their genetic
formulae given, after which the author presents in tabular form the expected
ratios and the observed results in the second and third generations. She
concludes that the blue color is the result of two complementary factors, B and
C. The presence of these two factors alone produces the light blue flowers, and
the dark blue is brought about by the action of an intensifying factor A co-
operating with B and C. Unless both B and C are present the flower will be
white. The factor A acts as an intensifier only on the light blue of the petals
and has no effect on the color of the anthers, on the color of the seed, or on the
color of the veins in the petals. The factor B is not only one of the necessary
factors for the production of the blue flower color, but even without the
cooperation of C brings about the blue color of the anthers and the brown
color of the seeds, prevents the crinkling of the petals which, were it not present,
would be caused by the presence of C, and overcomes the tendency of C to
lessen the number and viability of the seeds. The factor C, besides producing,
with B, the blue color of the flower, brings about, when in a homozygous con-
dition, a deeper pigmentation of the veins in the petals; and causes, when B
is absent, a crinkling of the petals and a lessening in the number and viability
of the seeds. In respect to the color of the anthers, which results from the
presence of B } it is pointed out that although the 6 varieties studied are in
agreement with the interpretation given, there is a variety, which has not yet
been studied, that has blue flowers and yellow anthers. As this is contrary to
the conclusions arrived at from the 6 varieties investigated, the author suggests
that the factor B may be, not a single unit, but a complex, with some essential
part or factor lacking in the variety with blue petals and yellow stamens. On
the other hand, B may be a unit and the blue anthers may be lacking because
some other necessary factor besides B is lacking in that variety. An investi-
gation of this problem is promised. — Ben C. Helmick.
Physiological temperature and moisture indices. — In extending his studies
of the derivation and use of indices of temperature in relation to plant growth,
Livingston 2 ? distinguishes 3 classes of such indices. The first is the sum-
26 Tammes, Tine, Die genotypische Zusammensetzung einiger Yarietaten der-
selben Art'und ihr genetischer Zusammenhang. Extrait Recueil Trav. Bot. Xeer-
land. 12:217-278. 1915.
3 7 Liyixgston, B. E., Physiological temperature indices for the study of plant
growth in relation to climatic conditions. Physiol. Researches 1 : 399-420. figs. 4. 1916.
166 BOTANICAL GAZETTE [February
mation of the daily mean temperature, above a certain fixed minimum, through-
out the growing season. Such indices of temperature efficiencies for plant
growth have been used largely by phenological students, notably in Merriam's
"law of temperature control." An advance upon this method was suggested
by Livingston, 28 based upon the supposition that growth rate may follow the
chemical principle of van't Hoff, doubling with each increase of temperature
of io° C, and the present publication proposes to give the indices a value
based upon physiological experiment. Lehenbauer's 29 recent experiments
upon the growth rate of maize seedlings at different temperatures affords data
for the derivation of these indices which surpass those formerly proposed
in taking account of the recognized principle of temperature minima, optima,
and maxima; and also in showing a much greater rate of increase of index
value with rising temperature between 2° and 32 C. Charts showing the
climatic zonation of the United States according to each of the 3 classes of
indices are suggestive and interesting for study and comparison. The third
method clearly surpasses the others in correctness of principles involved, and
its indices are used by the same author 30 in deriving a single index for
both temperature and moisture. As a measure of the moisture conditions, the
ratio of annual rainfall to annual evaporation as suggested by Transeau is
used, and this ratio is multiplied by the summation index of temperature effi-
ciency for the same period, and the product is the proposed moisture- tempera-
ture index. The general scheme is a good one, and the resulting zonation of the
United States is interesting in spite of the utter inadequacy of the evaporation
data. It may be doubted also whether this rainfall evaporation ratio expresses
the moisture conditions which determine plant growth as well as the soil
moisture-evaporation ratio suggested by the reviewer. It is true that here
again the lack of data will prevent the effective use of this ratio for years to
come. — Geo. D. Fuller.
Taxonomic notes. — Collins and Howe, 31 in studying specimens of red
algae from Bermuda, southern Florida, and North Carolina, have recognized
4 new species of Halytnenia.
Safford 32 has published Desmopsis as a new genus of Annonaceae, to
include 5 species from Mexico, Panama, and Costa Rica, that differ in several
important characters from the Old World Desmos (Unona Vahl).
28 Livingston, B. E., Box. Gaz. 56:349-375. 1913.
29 Lehenbauer, P. A., Growth of maize seedlings in relation to temperature.
Physiol. Researches 1:247-288. 1914.
30 Livingston, B. E., A single index to represent both moisture and temperature
conditions as related to plants. Physiol. Researches 1 1421-440. fig. 1. 1916.
-* 1 Collins, F. S., and Howe, M. A., Notes on species of Halytnenia. Bull. Torr.
Bot. Club 43:169-182. 1916.
32 Safford, W. E., Desmopsis, a new genus of Annonaceae. Bull. Torr. Bot.
Club 43:183-193. pis. 7-9. fig. 1.
1917] CURRENT LITERATURE 167
In the last number of Hooker's I cones Plantarum (V. upls. 3051-307 5 ,
June 19 16), the following new genera are described and figured: Pappobolus
Blake (Compositae) , Mischopleura Wernham (Ericaceae), Neowollastonia
Wernham (Apocynaceae) , Dalzielia Turrill (Asclepiadaceae) , Eriolopha Ridley
(Zingiberaceae) , Chloachne Stapf, Uranthoecium Stapf, and Danthoniopsis
Stapf (Gramineae). In addition to these 8 new genera, 7 new species are
described.
Koidzumi, 33 in continuing his studies of Castanaceae, has recognized
Synaedrys Lindl as a genus, extending it considerably, and has included under
tties transferred from Quercus. He also lists 234 species as remaining
Q
Bermuda
including 86 species representing 36 genera. New species are described in
Collema
West, 3 * in continuation of his studies of algae, has described a new marine
genus of the Volvocales (sub-family Carterieae), naming it Platymonas. He
also describes new species in Chlamydomonas (2) and Pteromcmas. — J. M. C.
Eocene floras. — The geographic area covered in the recent monograph by
Berry 36 is the mainland south of latitude 41 and east of longitude 100. The
Antillean and Mexican regions are not included even for comparison on account
of meager information in regard to them. The memoir is monumental in its
character, consisting of nearly 500 quarto pages and 117 plates. A few ferns
and monocotyledons are described, and no conifers. Most of the illustrations
represent impressions of dicotyledonous leaves. The only anatomical illus-
trations are of a Cupressinoxylon and a Laurinoxylon, which are of the con-
ventional and vague nature that too often characterizes such illustrations in
publications of the U.S. Geological Survey. Apparently the Survey either
should not publish anatomical data at all or intrust their preparation to some
one equipped with a modern anatomical training. An important and valuable
feature of the work is the attempt to correlate the presence of fossil forms with
the principles of phytogeography. This appears to be very well done and is
not open apparently to the grave objections which present themselves in the
case of the conifers of the Mesozoic, which for the most part have been wrongly
identified from their impressions and consequently cannot be used safely in
33 Kom^uMi
, _ — y
(Tokyo) 30:185-215. 1916.
II. Bot. Magazine
160. 1916.
Riddle, Lincoln W., The lichens of Bermuda. Bull. Torr. Bot. Club 43:145-
1916.
* West, G. S., Algological notes. XYIH-XXIII. Jour. Botany 54: 1-10. Jigs. 7*
36 Berry, E. W., The Lower Eocene floras of southeastern North America. U.S.
Geol. Survey. Professional paper 91. Washington. 1916.
168 BOTAMCAL GAZETTE [February
discussing geographical distribution. The author sets a high example for
American systematic paleobotanists. It is to be hoped, however, that the
paleobotanical activities of the U.S. Geological Survey will not in the long run
be confined to the systematic side, but that they will be extended, as has
already been done in the case of European countries, to the crucially important
although less abundant structural remains. — E. C. Jeffrey.
Lower Eocene plants. — Berry 37 has published an extensive paper on the
plants of the Lower Eocene of southeastern North America, being the result
of several years of work on the fossil plants of the southern coastal plain.
Naturally, much of the report deals with the stratigraphic relations illustrated
by the plants, but the systematic descriptions are of great botanical interest.
The orders represented, 34 in number, range from Pyrenomycetes to Rubiales,
but 29 of the orders are angiosperms. Caenomyces is a new genus of Pyreno-
mycetes, including 6 species. The pteridophytes are represented by 5 new
species, and Meniphylloides is proposed as a new genus of ferns. The gym-
nosperms are represented by 2 new species, one in Zamia and the other in
Anthrotaxis, while 4 new species, representing as many genera, belong to the
monocotyledons.
The bulk of the report, however, deals with the dicotyledons, 228 new
species being described, distributed among 96 genera, among which are 7
new genera as follows: Paraengelhardtia ( Juglandaceae) , Kni ghtio phylhtm
(Proteaceae) , Dalbergites (Leguminosae) , Sterculiocarpiis (Sterculiaceae) ,
Bombacites (Bombaceae), Dillenites (Dilleniaceae), and T ernstr oemiies (Tern-
stroemiaceae). One of the marked features in the composition of this dicoty-
ledonous flora is the abundance of leguminous plants, of which 53 new species
are described, 12 of which, for example, belong to Cassia. In addition to the
new species assigned definitely to recognized families, 14 new species are de-
scribed under form genera of uncertain relationship. — J. M. C.
Conjugate nuclei in Ascomycetes. — In a brief article, Miss Welseord 38
notes the fact that conjugate nuclei are common in the hyphae of well nourished
mycelia of Botrytis cinerea and Sderotinia Libertiana. In poorly nourished
mycelia the paired nuclei are absent, as the nuclei under such conditions have
time to move considerable distances apart before successive divisions occur.
Miss Welsford observes that if conjugate nuclei occur generally in the myce-
lium of Ascomycetes, their presence in the ascogenous hyphae does not have
the sexual significance usually attributed to it. — H. Hasselbrixg.
» Berry, E. W., The Lower Eocene floras of southeastern North America. U.S.
Geol. Survey. Professional paper 91. pp. 481. pis. 117. figs. 16. 1916.
& Welsford, E. J., Conjugate nuclei in the Ascomycetes. Ann. Botany 30:415-
417- figs. 4* 1916.
VOLUME LXIII
NUMBER 3
THE
Botanical
Gazette
MARCH 1917
temperature and life duration of seeds
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 226
James Frederick Groves
(with FIVE figures)
Introduction
In this investigation I have sought to determine the extent to
which a study of the laws of the life duration of seeds at high
temperatures (50-100 C.) will explain the process of degeneration
of air-dried seeds at ordinary storage temperatures. In this con-
nection it seemed especially desirable to determine: (a) the tem-
perature coefficient (Q I0 ) for the death rate or life duration of seeds;
(b) to what extent the formula which Lepeschkin (22) applied
as a time-temperature formula for the coagulation of proteins and
as a life duration-temperature formula for active living plant cells
can be applied as a life duration-temperature formula to dry seeds;
and (c) how far the temperature coefficient (Q I0 ) on the one hand,
and the Lepeschkin formula on the other, when applied to actual
measurements at high temperatures serve as a means of approxi-
mating the life duration of air-dried seeds at ordinary storage
temperatures. With these questions in mind a number of deter-
minations have been made on wheat of the Turkey-red variety.
Historical
The effects of high tempera tun
the attention of investigators. In
Just
Trifolium prate n
showed that
C, and that
169
170 BOTANICAL GAZETTE [march
at lower temperatures (time of exposure not given) the speed of
germination fell with heating. Hohnel (17) in 1877 found that
most seeds with a moisture content below 3 per cent would endure
a temperature of no-125 C. for 15 minutes. In 1902 Dixon (13)
summarized the earlier work on high temperatures of seeds as
follows: "(a) imbibed protoplasm resists 30-40 C. more than the
optimum temperature; (b) dry protoplasm resists ioo° C. more than
the optimum temperature of the protoplasm of imbibed seeds
?>
time
temperature
time of germination
tat 30-60 per cent o
j
may be exposed to a temperature of 98 C. without losing their
ability to germinate, if first dried at 6o° C. for 24 hours and then
heated to 98 for 10 hours.
The cause of the loss of viability in old seeds has been a matter
of considerable discussion and investigation. Duvel (14) states
that seeds retain their viability longest in conditions which permit
least respiration, implying that the food materials are exhausted.
Acton (i), by a careful analysis of old and new seeds, found that
there was but a slight difference in their food content. In the
course of these investigations he discovered that there was consider-
able diastatic and proteolytic enzyme action in new seeds, while in
old seeds there was none. He assumed, therefore, that the loss
of viability is related to the loss of enzyme activity. The investi-
gations of Thompson (31), Waugh (m), and others furnish some
V
evidence for this conclusion. They found that old seeds with a
low percentage of germination, when soaked in enzyme solution,
showed an increase in viability. Brocq-Rousseau and Gain
(8, 9, 10, 11) in their earlier work found that enzymes gradually
disappear with age. They tested 300 species of seeds and found
sam
century.
enzymes in sam
as old as 200 years. In some cases the retention of enzymes was
attributed to the hard coats of the seeds, and the loss of viability
was stated to be due to some cause other than degeneration of
enzymes. Aspit and Gain (3) found enzyme activity in seeds
1917] GROVES— DURATION OF SEEDS 171
long dead and in seeds killed by anesthetics. Miss White (33)
found no increase in the germination of seeds soaked in enzyme
solutions, but rather a decrease due to an increased fungal action.
She found the life duration of Triticum to be 17 years, with no loss
of enzyme activity. According to her work the enzyme theory of
the loss of viability is not tenable.
Some very significant work has been done on the time-
temperature relation of coagulation of protein both in vitro and
in the living cell. Buglia (7) found that the time required for the
coagulation of blood serum varies with the temperature used.
The time of coagulation was found to be a logarithmic function of
the temperature. Chick and Martin (12) found that the time
required to precipitate egg albumen and haemoglobin from solu-
tion varies with the temperature and with the concentration of
the solution. Lepeschkin (22) showed that the death of active
plant cells by supramaximal temperatures is due to the coagulation
of the cell protoplasm. He applied a logarithmic formula to express
the relation of temperature to the time of coagulation of proteins
in vitro as well as in the living cell. By the application of this
formula to the determined time for coagulation at any two tempera-
tures, one can calculate the time necessary for coagulation at any
other temperature. On this basis Lepeschkin calculated the life
duration of active Tradescantia cells at 20 C. to be $$ days, and
at zero to be 3 years. He believes that the life duration of plant
cells is very much longer than indicated because of a redispersal
process, carried on by the active living cells, which counteracts
the coagulation process.
The results of many workers in this field have been well sum-
marized in a recent monograph by Kanitz (20), who has brought
together the literature from several related subjects. He shows
that in general the effect of temperature upon the rate of chemical
processes is governed by the Van't Hoff law, that is, the coefficient
for a rise in temperature of io° C. (Q I0 ) is 2 to 3. From the experi-
mental results at any two temperatures the value of Q I0 may be
calculated from the following equation (referred to as formula 1
and formula 2) :
IO IP (log * a -lpft k t )
Qio=[ k ) or (?i~=io
172 BOTANICAL GAZETTE [march
Method
In order to obtain constant temperatures for heating the seeds,
rmostat
It consisted of an
external water bath heated by an electric stove. In this bath was
placed a similar vessel of smaller dimensions which was closed at
the top and connected with a water-cooled reflux condenser.
Methyl or ethyl alcohol or mixtures of methyl or ethyl alcohol
with water was used for temperatures 64-99 C. The tempera-
ture during the time of an experiment showed a fluctuation of less
than =±=o?i C. For lower temperatures, where the time was much
prolonged, the usual water-jacketed incubator was used. This
was well wrapped with heavy woolen blankets. The temperature
of the incubator was regulated by the automatic electric apparatus
devised by Land (21). It gave a very equable temperature,
showing a straight line on the drum of an ordinary recording
thermometer.
The seeds were heated in the thermostat by inserting securely
corked test tubes, each containing 100 selected seeds, through
perforations in the top of the inner vessel. These test tubes were
suspended by threads passed through the perforations, and the
threads were then secured by corks which closed the openings.
Many of these tubes were inserted at the same time and removed
in duplicate at successive intervals. Seeds were heated in the
in which k 2 is the rate of reaction obtained at temperature t 2 , and
ki the rate of reaction obtained at temperature h.
Many processes in living organisms show a temperature coeffi-
cient approximately that of the Van't Hoff law within certain
temperature limits. Some of these show high values of Qi at
lower or at critical temperatures. High values of Q I0 are found f
also for life duration and for coagulation or denaturing of proteins.
Kanitz (20) brings out more clearly the relation of tempera-
ture to the rate of life processes by recalculating Q I0 at the various
temperature intervals instead of giving only the average coefficient
for the whole temperature range. In this way it is found that in
many cases Qi is not a constant at all intervals of temperature,
but shows decreasing values with rise of temperature.
-
1917]
GROVES— DURATION OF SEEDS
173
Water
Supply
lank
Condenser
5 Team Outlet
Under Water
Thermcmeter
Containing 5eed
External Water Bath
Alcohol Water Bath
Electric Heater
Thermostat for Heating Seeds.
Fig. 1
174 BOTANICAL GAZETTE [march
incubator in a similar manner by inserting the tubes through
perforations in the top. This avoided the main source of tempera-
ture fluctuation in the incubator, opening the door.
After the seeds were heated they were sterilized by washing
for 2 or 3 minutes in a n/$o solution of silver nitrate. While in
this solution the seeds were stirred thoroughly in order to free them
of all air bubbles. Then they were washed thoroughly in sterile
distilled water to remove the excess of silver nitrate which would
injure the seedlings when germinated. Sckroeder (28, 29) has
permeable
many
seeds confirmed his conclusions. The importance of sterilizing
the seeds is realized when we consider that in some cases the
germination was delayed as much as 20 days. Miss Muller (25),
in her work on germination of heated seeds, found that after 10
days seeds were either germinated or destroyed by mold. By
some
from
growth for several weeks.
After sterilizing and washing, the seeds were germinated in large
Petri dishes containing a layer of moist cotton covered with a
layer of filter paper. The dishes were sterilized at 140 C, and
maintain
conditions.
tempera
germination
moisture
from time
time, and only very slight variations occurred in any one of the
3 moisture content experiments. The Duvel (15) method was
used parallel with the ordinary oven drying method and the two
gave concordant results. Since the Duvel method requires less
than an hour to make a test, it was possible to check the moisture
content before filling the tubes for each trial.
Results
The effects of heating seeds is well shown in table I, which is
a daily record of the germination of a time series heated at 87? 5 C.
Seeds were considered normally germinated when both root and
p
1917]
GROVES— DURATION OF SEEDS
175
stem had broken through the seed coat. When only the root or
the shoot appeared, the seeds were considered partially germinated.
Partial germination is represented in this table by the figures
in small type. The delay in time of germination as the time of
exposure increased is strikingly shown here. The controls usually
TABLE I
>
Record Sheet No. 21
Temp: 87. 5 'C. Moisture
Turkish Red Wheat
April 10, /9I4.
EH^i i£
Cont/vt
7 Mm.
dM/n
9M/n
lOM/n
H Mm
/2Min
l3M/n.
92 92
o
o
98 98
/o //
/J
/4
/7
/£>
98\98
98 98 98
98198
SS 6/
64167
■f
7a\7e 7e 72 73 74
6
/0\e5\30 35
/
/
/
/
59\59
8 /O
4
Rgr \Cen?
/&►/■ W/t
v
fbr Cent \5er/7?>'r?0.
vr/i
/
/8 25 28 32
4
j
o
o
O O
germinate in about 2 days, while some of the treated seeds were
delayed for 18-20 days. The relation between time of heating and
the percentage of germination is shown in the table. There is a
gradual decrease in the percentage of germination with increased
time of heating. After the delayed seeds germinate their growth is
much slower than that of unheated seeds. It should be noted
that the effects here of heating are similar to those produced by
the aging of seeds stored at room temperature. This indicates
176 BOTANICAL GAZETTE [march
that there may be a similar change in the two cases. The change
occurs rapidly at the high temperature, but slowly at the low
temperature.
Some investigators have used the time required to kill all
seeds as the end point. In this work we have selected the time
required to kill 75 % per cent of the seeds as the end point. This is
more desirable because there seems to be considerable discrepancy
in the resistance of a few stronger seeds. This end point for 12 per
cent moisture and various temperatures was obtained as shown in
table II. While there are some irregularities, there is a definite
relation between temperature and time of exposure necessary for
killing 75 per cent of the seeds.
The time-temperature formula suggested by Lepeschkin (22)
has been used here to calculate the life duration of the seeds. By
determining the time required to kill seeds at any two definite
temperatures, the time for killing seeds at any other temperature
can be calculated. The formula (referred to as formula 3) is:
T=a—b log Z
in which T is the temperature in degrees Centigrade, Z is the time
in minutes, and a and b are constants. If the loss of viability
of seeds during storage is a matter of coagulation of cell proteins of
the embryo, this time-temperature formula for the coagulation of
proteins should be applicable as a temperature-life duration formula
for seeds. In experiment the life duration determined must be at
relatively high temperatures, ranging from 50 to ioo° C. for
air-dried seeds.
In formula 3 constants a and b may be calculated by substitut-
ing the time and temperature of any two trials and solving for a
and b in the two equations. This is the
by Lepeschkin (22). In order to weigh all determinations equally,
the constants in this paper are calculated by the method of least
squares. The values of the constants and the life duration found
in each experiment were substituted in the equation and the theo-
retical temperatures were calculated. The values are shown in
table II- A comparison of these found and calculated temperatures
shows that a comparatively close agreement exists. The dis-
crepancies are within the limits of experimental error.
me
t
1917]
GROVES— DURATION OF SEEDS
177
b
Fig. 2 is a time
curve representing the experi-
mental data shown in table II for wheat with 12 per cent
w
40
6C
90
/OO
J40
60
/6C
^oo ex
e*o
eoo Xfo
Fro. 2
TABLE II
Germination record of Turkey-red wheat 12 per cent moisture; theoretical
temperature calculated by the formula T—a~b\ogZ; T is temperature (Centigrade);
Z is time in minutes; a and b are constants; = 96.87; 6=10.4; value of Q> as cal-
culated by method of least squares = 10. 14.
Time in minutes
7
8
9
10
18
45
So
5°
120
315
Calculated
temperature
Experimental
temperature
88.
87.
87.
86.
84.
S3-
79
79-
79-
75-
70.
i°C.
s
o
5
6
7
7
2
2
2
9
Q
10
89
. 2° C.|
87
■7
87
5
87
5
84
4
84
4
78
9 \
79
1
78
5
75
8
7i
3 J
6.0Q
(10 3)
12.94
(7-6)
Predicted life duration: 50* C, about 22.3 days; 25 C, about 15.5 years; 20 C, about 46.9
; o°C, about 393 years.
moisture
orclinates
degrees Centigrade and the
time. Except for
gularities which
178
BOTANICAL GAZETTE
[march
occur at 78 and 79 , there appears a marked agreement in the
data and the points representing the experimental data approxi-
n for
mate a smooth curve. Table II shows the value of Q*
experimental temperatures as calculated by formula 2.
tables II-IV partial germination is represented by the figur
parentheses.
In
ea,ooa
Fig. 3
Table III shows the found and calculated data for wheat with
9 per cent moisture. The calculated temperatures were obtained
by the same method as those in table II, and here as before there
is a close agreement between the theoretical and observed values.
express
time-temperature
Practically all of the points representing
smooth
Table III shows
Q I0 for experimental temperatures as calculated bj
formula
1917]
GROVES— DURATION OF SEEDS
179
Table IV shows a limited number of data for wheat with 17. 5
per cent moisture. As would be expected, the time required to
TABLE III
Germination record of Turkey-red wheat 9 per cent moisture; theoretical tempera-
ture calculated by formula T=a — blogZ; T is temperature (Centigrade); Z is time
in minutes; a and b are constants; = 100.8; 2> = io.4; value of Q ro as calculated
by method of least squares = 9 . 23.
Time in minutes
8
27
45
I40
435
810
2340(1.6 days).
7200(5.0 days).
19440(13.5 days)
Calculated
temperature
91 4° C.
859
83.6
82.1
78.5
73-4
70.5
65 7
60.6
56.2
Experimental
temperature
90. 8° C.
85-7
84.2
835
79.8
74-4
70.8
66.0
60.6
56.3
10
13-49
(". o)
7 03
(90)
8.51
(10.2)
Predicted life duration: 50" C, about 53.4 days; 25° C, about 37.3 years; 20° C, about in. 2
years; o° C, about 938 . 5 years.
kill such seeds at the temperatures used in the former experiments
is exceedingly short. The error due to the time required for the
TABLE IV
Germination record of Turkey-red wheat 17.5 per cent moisture; theoretical
temperature calculated by formula T=a— b log Z; T is temperature (Centigrade);
Z is time in minutes; a and b are constants; = 81.73; £ = 8.04; value of Q m as
calculated by method of least squares for last 4 temperatures = 1 6 . 45 .
Time in minutes
3°-
3-75
40.
5-5-
8.0.
230.
140.0.
440.0.
Calculated
temperature
77
77
76
75
74
70
64
60
9
1
9
8
5
8
5
5
C
87
83
83
79
74
70
64
60
1
6
1
5
7
5
4
6
C.
Experimental
temperature
Q
10
2.22
(7-6)
4.90
(90)
19.71
(9 9)
o Predicted life duration: 50° C, about 6. 1 days; 25 C, about 21.6 years; 20 C, about 64.4 years;
o C, about 2800 years.
seeds to attain the temperature of the bath is therefore very appar-
ent here. The data of this table are expressed also as a time-
i8o
BOTANICAL GAZETTE
[march
temperature
Here again there is close agreement
Q
10
1 the calculated values,
perimental temperatures
Table IV shows
formula
arithm
time for wheat with 9, 12, and 17. 5 per cent moisture
of the constants is found to have a common value in 1
Since one
I
Currr storing relation
Si&Hmm ffmftrafvr* and
t/fffi.
Moisture '(7.5 %
60 SO /00 £0 /40 J*0 #0 200 220 240 260 280 J00 J20 J40 J60 JOO 400 420 440 4§S
Fig. 4
per cent moisture curves, they are parallel. Since they were
obtained under identical conditions, one may surmise that the
curves in which temperatures in degrees Centigrade are plotted
against time in minutes are parallel. Sufficient data are not avail-
able with the 17.5 per cent moisture content at experimentally reli-
able time intervals to justify a conclusive generalization. The
curve for the 17.5 per cent moisture content deviates upward
from a straight line in the lower time range. This is due to the
fact that a considerable part of the short period of exposure was
consumed in heating the seed up to the temperature of the
bath. s *
1917]
GROVES— DURATION OF SEEDS
181
>
TEMPERATURE COEFFICIENT
The temperature coefficient (Q I0 ) of the life duration of wheat
was found to vary with the moisture content. The average value
for 9 per cent moisture, calculated by the method of least squares,
is 9.23; for 12 per cent moisture, 10.14; and for 17.5 per cent
working with barley grains,
moisture, 9.83. Goodspeed (16),
found a coefficient varying from 10 to 16 as calculated by Kanitz
(20). The result obtained by Goodspeed is marred by the lack
Fig. 5
rmination and control of the moisture
Since the
seeds were soaked for only one hour previous to heating, they had
maximum amount
Such seeds, when
temperatures
time, show considerable difference in
by calculation, according to formula
I find
Q I0 , and on
from
Av res
(c
I
182 BOTANICAL GAZETTE [march
average coefficient of 1.47 per degree Centigrade. I have calcu-
lated his data according to formula 2 and find the value of Qi to
vary from 5 to 88. There is a definite break in his data which pre-
vents them from falling on a smooth curve. This is probably
due to some uncontrolled factor in experimentation. I find that
the data in other articles cited here, both on life duration and
coagulation of proteins, give smooth curves.
The Qio coefficient for life duration of animals, so far as worked,
is very much larger than for plants. Loeb (23) found a Qi value
varying from 240 to 1450 for fertilized sea urchin eggs, while for
unfertilized eggs he found a value of 600. Moore (24) found a
Qio value varying from 485 to 3900 for the stems of Tubular ia
crocea.
The Qio value for the coagulation of proteins shows a wide
a
variation for the various proteins or different conditions of the same
protein as calculated by Kanitz (20). Chick and Martin (12)
found a value of 14 for haemoglobin and 635 for egg albumen. I
have calculated the value of Qi for Buglia's (7) data and find it
to be about 15 for blood serum, 760 for fresh muscle, 45 for neutral
albumen, and 240 for neutral concentrated albumen.
The low Qio coefficients found for plants mean that they can
endure various supramaximal temperatures for relatively long
periods as compared with animals with the larger Q I0 coefficients.
This may be of great importance to plants, since in many habitats
they are unable to avoid intense radiant energy. The radiant
energy is largely absorbed and the plants attain temperatures as
much as 2 8° C. above the air temperatures, and certainly several
degrees above the maximal for growth (2, 6, 26, 30). In general
the animal is able to avoid such superheating through locomotion.
As bearing on this point many more determinations are needed
both on animals and on plants of a variety of habits and habitats.
The difference between the temperature coefficients for plants
and animals shows itself in an experimental way. There is the
possibility of employing a much greater range of temperature in
plant material. In the investigations on animals previously
cited the range used is about io° C, while in investigations on
plants the range is 20 C. or more. In plants a much greater range
»
I
1917] GROVES— DURATION OF SEEDS 183
would be possible were it not for the fact that the small coefficients
give life durations too long for convenience in experimentation at
temperatures not considerably above the maximum.
The difference between plants and animals in the size of the
coefficients manifests itself in another way. In the investigations
with animals the temperatures used are largely below 45 C, while
with plants it is not uncommon to use temperatures above 70 C.
and obtain an easily measurable life duration. The maximum
temperature usable is determined also in part by other factors, such
as percentage of water present and the general attunement of the
particular plant to the temperature. The lower the percentage
of water in the seed, the higher the temperature that can be used
with it. It is probable also that in forms like Ulothrix and Hy-
drurus, having maxima below 24 C. (27), the possible experimental
temperatures would not run so high.
Discussion
The rather close agreement between calculated and- found
time-temperature formula for the coagu
lation of protein can be applied as a temperature-life duration
formula
ments.
accumulation
I make it possible to find some other equation which expresses more
J adequately the relationship between the variables involved. In
the experiments on wheat of 9 and 1 2 per cent moisture the average
deviation of the observed from the calculated temperatures is
less than 1 per cent. The corresponding average deviation for
the 17.5 per cent moisture content is about 8 per cent. The
unexpectedly large error with the 17.5 per cent moisture content
is due to the previously noted fact that a considerable part of the
time of exposure is consumed in heating the seeds up to the tempera-
ture of the bath. The uniformly increasing deviation of the
observed temperatures with short periods of time shows that
greater accuracy is possible with long time exposures.
While in many reactions there is a consistent decrease in the
value of the coefficient Q I0 as the temperature increases, we do not
find such a trend here. Compared with animal tissue, the value of
1 84
BOTANICAL GAZETTE
[march
the coefficient is small and compares in magnitude with the value
*
found by other workers on plant tissue. The range in the value of
the coefficients is small, as indicated by the fact that the data fall
on comparatively smooth curves. The coefficient Q I0 as calcu-
lated from the data (for 12 per cent moisture) in table II by the
method of least squares is 10.14. When the temperature and
time-differences in formula 2 are so small that they are comparable
with the errors of observation then the numerical evaluation of
Q I0 becomes highly inaccurate. But when the time and tempera-
ture differences are large enough to render ineffective the errors
of observation, then the calculated coefficient Qi is comparable
with the value obtained by the method of least squares.
The coefficient Q J0 for 9 per cent moisture content was found to
be 9.23 as calculated by the method of least squares from the
data in table III. Similarly, the coefficient for 17.5 per cent mois-
ture content was found to be 16.45 when calculated by the same
method, using the 4 highest time observations in table IV. The
4 lowest time observations were ignored on account of the inaccu-
racy introduced by the time required for the seeds to attain the
temperature of the bath, as previously explained.
A number of longevities have been calculated by formula 3
for the low temperatures at different moisture contents. With
the relatively short range of temperatures used in these experi-
ments, considerable error may appear in predicted longevities,
especially at low temperatures. When such calculated longevities
are compared with observed values, they are found usually to be
considerably too large, indicating that other processes may also
be effective in causing loss of viability. Since hard-coated seeds
have long vitality records, it seems quite possible that this is
related to the absence of oxygen and low water content.
Much more work is needed to determine how nearly one can
thus approximate longevities from measurements made at high
temperatures. Determinations should be made on the life duration
of seeds with low moisture content. Also similar determinations
should be made for a long-lived seed, such as sweet clover, for
which we have reliable records of longevity, as well as short-lived
(
1917] GROVES— DURATION OF SEEDS 1S5
seeds, such as Drosera, willow, and poplar. A series of determina-
tions should also be made on seeds at constant temperature with
variations in moisture content to ascertain the relations existing
between moisture content and life duration.
The data show that the Lepeschkin formula applies as a
temperature-life duration formula for seeds at the temperatures
used in these experiments, but there are several considerations
that may limit its application at lower temperatures, including
ordinary storage temperatures. (1) Increase of acidity of seeds
will hasten the coagulation of the cell proteins; such a change is
known to occur in the seeds of certain Rosaceae (15a), at least if
stored in the imbibed condition. (2) Lepeschkin (22) found that
in active plant cells a redispersal of cell proteins is going on coin-
cidentally with coagulation. As a consequence, at high tempera-
tures where the coagulation was rapid, the found and calculated
life durations agree closely; while at lower temperatures, where
redispersal is prominent, the calculated life durations are much
shorter than the found values. In seeds the calculated values are
usually much greater than records of longevity at room tempera-
tures. This indicates that the redispersal process is not going
on in relatively dry seeds, or, if it is, it is more than counteracted
by some other process. (3) A slight error in the value of the
constant b in formula 3 will give a relatively large absolute error
for a life duration at low temperatures such as o° C. At higher
temperatures the absolute error becomes less. (4) The lower
the water content of seeds, the more heating they withstand and
the greater the longevity at moderate and lower temperatures.
This law has its limits, for excessive drying is itself injurious. In
seeds that will endure desiccation, injury sets in with a reduction
of the water content considerably below 2 per cent, while in forms
like Drosera it appears before air-dry condition is reached. The
formula, of course, is limited to degrees of desiccation less marked
than those producing injury. (5) It is possible that slow oxidation
may limit the longevity of seeds. If this be true, hard seeds with
their coats impervious to gases along with their constant low per-
centage of water are in an especially favorable condition for the
i86
BOTANICAL GAZETTE
[march
marked longevity which they show. Wheat seeds stored in absence
of oxygen might give longevities more comparable with calculated
values.
Summary
i. The life durations of wheat with 9 per cent moisture at the
various temperatures are:
Life durations in
minutes
8
27 45
\
A1Z
810
2340
7200
19440
[
~-r— -TkJU
Temperatures in de-
grees Centigrade . . .
90.8
85.7
84.2
835
79.8
74-4
7 o.8
66.O
6O.6
S6.3
2. The life durations for 12 per cent moisture are:
Life durations in minutes . . .
Temperatures in degrees
7
8
Centigrade
92
9
10
.287.
7
87. 5
87-5
J 5
84.4
18 45
84.4
78.9
5°
50
120 XI
315
79-i 78.5 75-8
7i -3
3. The life durations for 17.5 per cent moisture are:
Life durations in minutes
Temperatures in degrees Centigrade
30
3-75
4.0
5-5
8.0
23.0
140.0
87.1
83.6
83,1
79-5
74-7
70S
64.4
440.0
60.6
4. The application of the Lepeschkin formula at high tempera-
tures as checked by actual measurements gives an average error of
0.6 per cent for 9 per cent of moisture; 0.8 per cent for 12 per
cent of moisture; and 8. 25 per cent for 17.5 per cent of moisture.
5. The data available for testing the application of the formula
at storage temperatures are exceedingly limited. White found
that 25 per cent of wheat would grow after being stored for 8.5
years. Assuming that they w T ere exposed to an average tempera-
ture of 20 C. and had an average moisture content of 12 per cent
according to formula 3, applied to the experimental data of this
paper, they should have a life duration of 15.5 years. However,
since the variations and averages of temperature and moisture,
together with other conditions, are not known, we are not justified
in pushing comparisons too far.
1917] GROVES— DURATION OF SEEDS 187
No definite trend appears in the value of the coefficient Q
10
*-^
limits. For wheat wi
from
average of 9.23; for 12 per cent moisture the range varies from
4.8 to 12.6 with an average of 10. 14; while for 17.5 per cent the
range varies from 2 to 20 with an average of about 10 for the whole
scope of the experiment.
7. Since the range of temperature used in these experiments
is comparatively short, we are not justified in placing too much
emphasis on predicted longevities at low temperatures. Such
longevities as have been calculated by formula 3 are large when
compared with observed longevities by White and others.
8. This work shows possibilities of throwing some light on the
nature of the processes of the loss of viability in seeds in storage
conditions. It also makes possible a quantitative statement of the
significance of various storage conditions, especially moisture
content and temperature, upon the longevity of seeds.
*
I wish to acknowledge many helpful suggestions by Dr. William
Crocker and Dr. Sophia Eckerson, under whose direction this
work has been done. I am also indebted to Mr. L. L. Thurstone of
the Carnegie Institute of Technology for aid and advice in making
mathematical calculations.
University of Wyoming
Laramie, Wyo.
LITERATURE CITED
1. Acton, E. H., Changes in reserve material of wheat on keeping. Ann.
Botany 7:383-387. 1893.
2. Askenasy, E., t)ber die Temperatur, welche Pflanzen im Sonnenlicht
annehmen. Bot. Zeit. 33:442-455. 1875.
J
propriete diastasique.
8-60
4- Ayres, A. H., The temperature coefficient of the duration of life of Cera-
fnium tenuis simum. Bot. Gaz. 52:65-69. 1916.
5. Becquerel, P., Recherches sur la vie latente des graines. Ann. Sci. Nat.
Bot. 5:193-320. 1907.
6. Blackman, F. F., and Matthaei, A., Quantitative study of CO* assim-
ilation and leaf temperature in natural illumination. Proc. Roy. Soc.
London B 76:402-460. 1905.
i88 BOTANICAL GAZETTE [march
7. Buglia, G., Uber die Hitzegerinnung von fliissigen und festen organischen
Kolloiden. Zeitsch. Chem. und Ind. der Kolloide. 5:291-293. 1909.
8. Brocq-Rousseau, and Gain, E., Sur Texistence d'un peroxydiastase dans
les graines seches. Compt. Rend. Acad. Sci. 145:1297-1298. 1907.
9. , Sur la duree des peroxydiastases des graines. Compt. Rend.
Acad. Sci. 146:545-548. 1908.
10. , Oxydases et peroxydiastases des graines. Rev. Gen. Bot. 21:55-
-
62. 1909.
11. , Sur la presence de Famylase dans les vieilles graines. Compt.
Rend. Acad. Sci. 148:359-361. 1909.
12. Chick, H., and Martin, A. J., On heat coagulation of proteins. Jour.
Physiol. 40:404-430. 1910.
13. Dixon, H. H., Germination and high temperatures. Notes from Bot.
Sch. of Trinity Coll. Dublin 5:176-186. 1902.
14. Duvel, J. W. T., Vitality and germination of seeds. U.S. Dept. Agric,
Bur. PL Ind. Bull. no. 58. 1904.
15. , A moisture tester for grain and other substances and how to use it.
- U.S. Dept. Agric, Bur. PI. Ind. Cir. 72. 1910.
15a. Eckerson, Sophia, A physiological and chemical study of after-ripening.
Box. Gaz. 55:286-299. 1913.
16. Goodspeed, H. T., Temperature coefficient of the duration of life of barley
grains. Bot. Gaz. 51:220-224. 191 1.
17. Hohnel, F., Welche Warmgrade trokens Samen ertragen, ohne ihre
Keimfahigkeit einzubiissen. Wissenschaftlich-praktische Untersuchungen
auf dem Gebiete des Pflanzenbaues. 2:77-88. 1877.
18. Jodin, M. V., Sur la resistance des graines aux temperatur elevees. Compt.
Rend. Acad. Sci. 129:893-894. 1899.
19. Just, L., tJber die Wirkungen Temperaturen auf die Keimfahigkeit der
Samen von Trifolium. Bot. Zeit. 33:51-52. 1875.
20. Kanitz, Aristides, Temperatur und Lebensvorgange. Gebriider Born-
traeger. Berlin. 191 5.
21. Land, W. J. G., An electrical constant temperature apparatus. Bot.
Gaz. 5 2 -*39i-399- 1911-
22. Lepeschkin, W. W., Zur Kenntnis der Einwirkung supramaximal
Temperaturen auf die Pflanze. Ber. Deutsch. Bot. Gesells. 30:703-714-
1913
J., liber Temperaturkoeffizienten
Thiere und iiber die Ursache des natiirlichen Todes. Archiv. Ges. Physiol.
124:411-427. 1908.
24. Moore, A. R., The temperature coefficient of the duration of life in
Tubular ia crocea. Arch. Entwicklungsmech. 29:287-289. 1910.
25
keimlingen ertragenen hi
heiten. 23:193-198. 1913.
Weizen-
Zschr. Pflanzenkrank-
1917] GROVES— DURATION OF SEEDS 189
26. Pearson, H. H. W., Observations on the internal temperatures of Euphor-
bia virosa and of Aloe dichotoma. Annals Bolus Herb. 1 141-66. 1914.
27. Pfeffer, W., Plant physiology, Eng. ed. Vol. I. pp. 76. 1913.
28. Schroeder, H., Uber die selecktivpermeable Hiille des Weizenkornes.
Flora 102:186-208. 1911. See Review Bot. Gaz. 52:79-80. 1911.
29. , Uber die Einwirkung von Silbernitrat auf die Keimfahigkeit von
Getreidekornen. Biol. Centralbl. 35:8-24. 191 5.
30. Smith, A. M., On the internal temperature of leaves in tropical insolation.
Ann. Royal Bot. Gard. Peradeniya 4:229-298. 1909.
31. Thompson, A., Zur Verhalten alter Samen gegen Ferment losungen.
Gartenflora 45:344-345. 1896.
32. Waugh, F. A., Enzymatic ferments in plant physiology. Science N.S.
6:950. 1897.
33. White, J., Ferments and latent life of resting seeds. Proc. Roy. Soc.
B 81:417-442. 1909.
I
A REPORT ON SOME ALLOCTHONOUS PEAT DEPOSITS
OF FLORIDA 1
PART II: MORPHOLOGICAL
Carl C. Forsaith
I
(WITH PLATES X AND Xl)
Previous to the eighteenth century the question concerning the
origin of coal was not debatable, since it was taken for granted that
it had arisen as a result of special creation, or during the Noachian
deluge by sedimentation (14). About 100 years ago, however, the
increasing value of coal in the industrial world led many investiga-
tors to seek a scientific solution for the problem. One of them,
Von Beroldingen, came to the conclusion in 1778 that coal was
transformed peat similar to that now found in swamps. After this
first step in the right direction, many other students formulated
theories as to how the process had taken place. Out of the result-
ing heterogeneous mass of contentions only two tenets have sur-
vived, namely, the allocthonous and autocthonous modes of peat
and coal formation. All modern students of the problem are
agreed that ancient beds have been produced by an accumulation
of organic detritus derived from the old lycopod flora, but there
*
are important differences of opinion still as to the method by which
this has been accomplished.
Since detailed and elaborate presentations of the drift and in
situ hypotheses have found a place in many publications upon the
subject, more than a brief review of them would be superfluous in
this connection (8, 9, 10, 11, 14, 15). Those favoring the first
doctrine maintain that these accumulations of much comminuted
plant debris, commingled with the more resistant elements, such as
spores from vascular cryptograms, carbonized wood (the " mother of
coal"), cutinized parts of plants, etc., were deposited very slowly
in the bottoms of permanent and open bodies of water, similar to
1 Contribution from the Laboratories of Plant Morphology of Harvard Uni-
versity.
Botanical Gazette, vol. 63]
[190
igi7] FORSAITH—ALLOCTHOXOUS PEAT 191
the method characteristic of lacustrine peat beds. Those opposing
this doctrine, the autocthonists, reject the idea that this represents
a sedimentation of plant derivatives in open water, but contend that
it consists of a gradual amassing of successive generations of lowland
plants by prostration in situ. The strata, thus exposed, were
preserved from decay by a permanent though concealed water sup-
ply, as is true and characteristic of the upper stratum of peat
deposits in our swamps.
The solution of this vexatious problem, as to which of the two
processes is the more probable, has been attempted for the most
part by geologists, and naturally enough they have sought explana-
tion topographically. To be sure, the results obtained by numer-
ous investigators in this direction have furnished many valuable
data relative to the formation of coal beds, although many of the
proofs upon which their conclusions are based are open to serious
objection. For example, the presence of stigmarioid roots in
coal beds and the supporting shales has been hailed frequently as
valuable testimony for an autocthonous origin of the strata in which
such structures are found. A broader survey of the problem shows
that these rootlike organs are by no means conclusive ground for
this deduction, since they also occur quite commonly in cannel
coal (a type universally agreed to have been formed in open water),
and consequently, a statement which argues equally for either
process is unreliable. In this same connection it might be well to
mention the quality of the so-called "fire clays " usually found below
coal beds. Those who believe that the majority of our coal seam
were laid down in situ see in the material conclusive proof that this
inorganic layer was at one time the subsoil of swamps, owing to an
absence of certain minerals which, in their opinion, could have
disappeared in no other way than through extraction by growing
plants. They fail, moreover, not only to show that this chemical
state could not have been brought about by prolonged leaching, but
also to account for similar strata in regions which reveal no evi-
dence that they at one time supported forests. In like manner,
other topographical features might be shown to present similar
objections in favor of sedimentation or an accumulation in place,
but this will suffice to illustrate that megascopic investigation alone
192 BOTAXICAL GAZETTE [march
is inadequate for reaching substantial conclusions, and therefore
it becomes necessary to seek some other means of attack, such as the
microscopical study of the material itself. It is evident that the
anatomy of coal and peat must be determined before the process
whereby they have been formed can be demonstrated clearly.
Studies of the formation of peat, and consequently coal, may be
divided into 3 main .classes: (1) topographical, 2 (2) ecological,
and (3) anatomical.
Topographical features have been considered sufficiently to
show that they, especially in relation to coal, are not entirely reli-
able as a final factor in determining the origin of all classes of
organic deposits. The ecology of peat forming plants likewise is
limited in its application, and accordingly will receive only a brief
consideration, for two reasons. In the first place, literature is
quite complete in its descriptions of the usual zones of growth
in sw^amps, including careful enumerations of all species of plants
characteristic of them (2, 6, 10, 11). In the second place, these
plants as such enter but little into the formation of the major
part of our peat deposits. Even in swamps only a very small
proportion (4-6 per cent) has been derived directly from this flora
growing in situ. As will be shown later, by far the greater portion
of our peat deposits represents a sedimentation of macerated
plant material in open bodies of water, and as such is not dependent
upon any one zone of growth, but rather upon all indiscriminately.
For this reason, the two first named branches of the discussion will
not be considered further, except for an occasional reference in
connection with the microscopical studies of several characteristic
peat beds.
Before discussing any special bog, however, it may be well to
introduce a brief description of allocthonous and autocthonous
peats as they appear under the microscope. It is possible, of
course, to discern with reasonable certainty the methods by which
any of our present peat deposits have been accumulated, since
one has but to choose his material from clearly defined areas; that
is, samples selected from modern lakes present detritus which
3 Forsaith, C. C, A report on some allocthonous peat deposits of Florida. Part I :
Topographical. Bot. Gaz. 62:32-52. 19 16.
t
19 1 7l FORSAITH—ALLOCTHONOUS PEAT 19s
has been deposited in open water, while the very upper stratum
of swamps is as equally typical of a cumulative origin in place. A
microscopical examination of preparations from open lake deposits
shows much minute material, both organic and inorganic. The
inorganic constituent may be quite variable, depending upon the
character of the surrounding country. If the shores and bottom of
the pond are of a sandy nature, and the environment much broken
by hills or mountains, a condition favorable for rapidly flowing
streams, much sand may be found. On the other hand, if the land
is quite level and densely forested, the buoyancy of inflowing streams
is much reduced, and the inwash from the shores does not carry any
large amount of inorganic material on account of a turflike pro-
tection. Consequently, the peat found in such regions will be
more or less free from earthy inclusions. This difference in the
mineral content of peat in rugged and level tracts is significant, and
may throw light upon the topography of coal beds during the period
of deposition. All available evidence indicates that the external
characters of coal beds were very similar to those just mentioned,
inasmuch as the land was flat and heavily forested.
Other inclusions found in peat are the calcareous remains of
Char a, limy silts, diatomaceous tests, and the shells of mollusks.
In addition to these mineral substances, which are small in amount,
there occurs the more strictly organic material, derived from more
or less macerated portions of plants and minute organisms of sedi-
mentary origin. Some of the most conspicuous of these elements,
as well as the most important from the scientific standpoint, are
pollen grains of the Abietineae and catkin-bearing angiosperms,
and spores from ferns, fungi, etc., representing bodies quite analo-
gous to the microspores and megaspores so habitually found in coal.
It is especially important to note that normally autocthonous
peats do not show the characteristic spore content so universally
found in open water formations. In addition to this microspore
material, one finds upon an examination of lacustrine samples a
rather large volume of amorphous material. Imbedded in the
flocculent matter, there appear ingredients the form of which is
more intact, such as woody and herbaceous plant fragments,
idioblasts from water lily stems, strips of cutinized epidermis, etc.
194 BOTANICAL GAZETTE [march
\
Besides these plant remains there are certain animal derivatives
characteristic of allocthonous peat; for example, ejecta from fish and
small aquatic animals, often containing pollen, diatoms, and bac-
teria; chitinized portions of insects; spicules from fresh water
sponges; infusorial bodies; and shells of mollusks and protozoans.
In contrast to the usual inclusions in allocthonous peat (pollen,
diatoms, spicules, idioblasts, etc.) there is the strictly autocthonous
peat composed of more or less disorganized plant debris. A
superficial examination of this material shows a light brown fibrous
or dark brown granular texture, depending upon whether or not
the included plants are herbaceous or woody. If the substance
is more completely decayed, owing to prolonged maceration and the
action of fungal enzymes (unhindered by a constant water covering
as is true of allocthonous layers) , the fallen plants may become so
structureless that they resemble humus rather than peat. Under
the microscope this form appears quite homogeneous in contrast
to the more fibrous and less decayed in situ peats, but seldom do
the distinguishing features of lacustrine peat appear, only a tangled
mass of roots, stems, and leaves in all stages of decay.
Thus it is apparent that there are two distinct types of peat,
presenting structures each peculiar to itself, dependent upon the
mode of deposition. If a specimen of coal, therefore, can be
shown to present a structure analogous to either of these two more
recent formations, it is but natural to assume that its composition
i
is due to similar processes of deposition. Strangely enough, this
has not been the usual mode of reasoning. Although it is authori-
tatively asserted that by far the greater number of the peat deposits
in the United States are allocthonous in origin, a diametrically
opposite view is maintained in respect to the genesis of coal beds.
Consequently it will be the object of this paper to show (i) that
these two types of peat are microscopically distinct; (2) that some
of the bogs (especially swamps) are not, as is usually believed, of
in situ derivation, but filled lakes in which the peat mainly repre-
sents the lacustrine or open water phase; and (3) that coals in
general show clearly the organization of allocthonous peat.
The methods used in carrying out these investigations were as
follows: Samples of different types of peat were carefully chosen
*
1917] FORSAITH—ALLOCTHOXOUS PEAT 195
from localities throughout a wide range extending from eastern
Canada to Florida. The numerous deposits were so selected
that all stages in the formation of peat beds were inspected, includ-
ing large and small deep lakes with sandy shores; filled lakes where
the zones of growth have entirely covered the former body of water
with a layer of accumulated vegetation; large and small shallow
lakes; and swamps and river estuaries. At every station a vertical
series of samples was secured at 1 ft. intervals. The probings
were made over a sufficient area to allow an estimation of the depth
and extent of each deposit. The specimens were obtained by the
use of a probe devised by Davis (3), and stored in cloth sacks. A
careful record was made concerning the topography of the region,
the gross character of the material, and the depth from which it
was taken. These specimens were later studied microscopically in
order to determine the correlation between the grosser structures
and the minute anatomy in respect to the mode of deposition.
Turning to the more detailed consideration of the several pro-
gressive steps in bog formation, Lake Weir in Florida may be con-
sidered as an example of the first stage. Sandy shores surround
this body of water, and probings show that there are no accumula-
tions of organic detritus nearer than 100 yards off shore; while
beyond this there appears a quite extensive stratum of lacustrine
peat. A gross examination of the material showed a consistent
homogeneous mass, the grayish color of which is due to a calcareous
silt. In addition, there appears a very large amount of diatoma-
ceous and limy remains of extinct plants and water animals. The
more peatlike content manifests itself as pollen of abietineous and
amentiferous derivation, amorphous matter, root fragments (the
stigmarioid rootlets so characteristic of certain samples of coal),
and herbaceous and ligneous elements from the higher plants.
Attention may now be directed to the more organic peats in
order to establish their relation to coal more definitely. In the
first place, I shall consider two forms, the one modern and the
other ancient, the origin of which is undoubted, namely, lake peat
and cannel coal. Samples of lacustrine ''muck" were found in
the centers of Lakes Newman, Orange, Griffin, Harris, Apopka,
Eustis, and many others in Florida, New Hampshire, Massa-
196 BOTANICAL GAZETTE [march
chusetts, and eastern Canada. In general, the samples obtained
by probings were deep brown and plastic. They were fine and
uniform in texture, without large or fibrous inclusions. As the
topographical features around Lake Harris, in Florida, dispel any
doubt as to the allocthonous genesis of the stratum there found,
preparations from it will be discussed in detail. Fig. 1 represents
a sample taken from near the top, and a careful study of it shows
clearly pollen grains imbedded in an amorphous mass of drifted
and windblown floatsam, ejecta from water animals, etc. A
small spore may also be observed. Sponge spicules and idioblasts
from water lily stems likewise appear.
A deposit very similar to the one just described was found
in Lake Dot, a small dumb-bell shaped body of water near Eustis.
This lake is very interesting as an example of those deep bowl-like
depressions, known as "lime sinks " (12), which are caused by a
subterranean solution of the underlying limestone, so that the roof,
becoming too thin to support its own weight, falls. Fig. 2 illus-
trates a section 3 feet from the top of a 9 ft. layer, and the characters
pictured were found by a study of the entire series to be uniform
throughout. It will be seen that this sample presents the usual
structureless material, ejecta, idioblasts, and pollen. In fact,
such structures as are usually encountered in lake "mud," but
absent from autocthonous deposits.
The central layers of the peat in Lake Eustis furnished the
material shown in fig. 3, which shows several diatoms of the Stauro-
nesis and Navicula type, in addition to spicules from decayed fresh
water sponges. The section also shows 3 specimens of the amoe-
boid Arcella. Other features already found to be characteristic of
lake precipitations are idioblasts, pollen, etc. Fig. 4 represents
a sample of peat much like those just considered, except that there
are more plant fragments. The section from which this sample
was taken depicts the type of peat found in Lake Orange a mile off
shore, and the topography of the region, as well as the microscopical
structure of the material, shows it to be of undoubted lacustrine
*
origin. Although many other deposits throughout a wide range
were studied, these 4 illustrations are sufficiently characteristic of
all deep water formations, as well as the lower layers of bogs, to
1917J FORSAITH—ALLOCTHONOUS PEAT 197
same
demonstrate the distinctive features of all such lacustrine accumula-
tions.
It is at least significant that cannel coal, which is universally
considered to be of open water derivation, should manifest the
structures so generally found in lake peat. Both of these fuels,
when microscopically examined, present a considerable spore
content. In fact some of the cannels (especially tasmanite) as
well as their modern homologues were found by Jeffrey (7) as a
result of studies of a great number of carefully prepared sections
to be almost entirely sporiferous. A somewhat clearer idea of
this correlation may be obtained by a reference to fig. 5, which
exhibits the organization of Kentucky cannel coal as it appears
under the microscope. Scattered throughout the section there
may be seen numerous light bodies, which are the flattened spores
of vascular cryptogams (homologues of the spores and pollen shown
in the illustrations of allocthonous peat). The long grayish
bands are indicative of metamorphosed bits of wood. Separating
amor
spores and lignitoid fragments are dense black masses of
>hous organic material. In comparing this illustration with
fig, 4, it is apparent that both the recent and prehistoric deposits
show a striking anatomical similarity. Thus it would appear
that whenever a peat and coal show like organization it has been
brought about by the same methods of deposition. It will con-
sequently be assumed in the sequel that similarity of structure, as
between peat and coal, implies an identical mode of origin.
Since the next stage in peat formation is illustrated by those
areas where the zones of growth are starting to form around the
shores, an example will be given. The shores around Lake Orange
in Florida show this fringe of water plants quite well. The peat
derived from this vegetation consists of fragments of amphibious
angiosperms, among which rushes, water lilies, pond weeds, etc.,
are common. Although the plants which are found in this zone
vary systematically in wide ranges, the peat formed by them is
uniform. Since the parts of plants which enter into the composi-
differences
omi
Although it is allocthonous, samples taken from this deposit are of
19S BOTANICAL GAZETTE [march
a light brown spongy nature. Fig. 6 presents a preparation from
this material, and it will be seen that there are many parts of plants
in a perfect state of preservation due to a perpetual covering by
water. Other structures more definitely related to lake peats are
idioblasts and parts of insects.
Florida is especially favorable for studies of this type of peat,
owing to an abundance of "saw grass" {Cladium) marshes about
Lakes Harris, Griffin, Apopka, and in fact generally throughout the
Everglades. If one were to rely solely upon a superficial examina-
tion of this material, representative of the later stage in herbaceous
marsh development, he would reach the conclusion that these
deposits have been formed by a growth of herbaceous plants in
situ. A detailed examination of samples from different depths,
however, shows that this is not a correct interpretation. On the
contrary, these paludal accumulations, with the exception of the
uppermost layers, are obviously allocthonous. A sample secured
3 ft. from the bottom of the marsh bordering Lake Harris is pictured
in fig. 7. This illustrates conclusively that the material has not
been formed in situ by a gradual amassing of fallen plants, but
rather by a floating together of drifted and wind-blown matter
similar to that characteristic of deeper lake deposits, as indicated
in figs. 1-4. The usual structures found in lacustrine peat, shown
in fig. 7, are pollen grains, idioblasts, plant fragments, ejecta, and
formless drift. Although no sponge spicules and diatoms appear in
the illustration, it should be added that they are of common occur-
rence. This kind of peat is usually encountered in the lower four-
fifths of "saw grass" marshes, as determined by vertical series of
samples. The upper layer, nevertheless, has been accumulated in
a different manner, since the microscope reveals only the tangled
remains of fallen herbaceous plants, and the structures usually
found in open water deposits are conspicuously absent. It is prob-
able that this distinct change in the process of deposition was
accomplished at some time when the material had so collected that
the mass w r as above w r ater, for a part of the year at least, so that
plants perishing in place were allowed to become more or less
reduced owing to exposure, and not permitted Jo float away and
become precipitated among the usual sedimentary detritus. It is
19 1 7] FORSAITII—ALLOCTHOXOUS PEAT 190
apparent that this peat, a very common type in the Florida lake
region, is not, as is ordinarily supposed, of autocthonous derivation;
but, on the contrary, is almost entirely allocthonous. It would
thus appear that the development of this form of deposit is in
accord with the general principle of sedimentation for peat and
f coal in general.
One of the most interesting phenomena in relation to the forma-
tion of peat beds is that illustrated by completely or nearly filled
lakes. As has previously been stated, there are several distinct
steps in the process, beginning with an open lake surrounded by
sandy shores, of which condition Lake Weir served as an example.
The next is seen where the herbaceous zone has crept in from the
shores, as illustrated by the "saw grass" marshes around Lake
Harris. The third stage is the conversion into a bog as a result
of drainage and the introduction of woody plants, which marks the
end of the process. Consequently, the value of this last formation
as a peat builder has in all probability been overestimated, since
the detritus formed by it directly comprises but a small proportion
of the whole, especially in the more tropical areas where perpetual
exposure is favorable to destructive activities. A series of samples
from one of these beds, if studied only superficially, shows two
ma
mat of fallen plants and roots, and the lower layer consisting of a
somewhat homogeneous mass of minute debris. This older plastic
material is believed by many w r riters to have resulted from a more
prolonged period of reduction of detritus similar to that found in the
upper part of the bed. This conclusion, derived from gross
examinations alone, is nevertheless misleading, and on this account
it seems advisable to refer to microscopic investigations. A bog
near Leesburg will serve to illustrate. A topographical study of this
area showed that it was at one time either an arm of Lake Harris
or a connecting link between Lake Harris and Lake Griffin. At
the present time the filling processes have reached completion, and
the entire area is now dry land bearing a dense forest of coniferous
and deciduous trees. Probings in several localities showed about
15 ft. of peat resting upon a stratum of bluish clay (the initial stage
of "fire clays" usually found under coal beds). Above this lamina
200 BOTANICAL GAZETTE [march
there occurs a layer of fine black peat, similar in form to that now
found in the open lakes. This is the "completely decomposed
stratum" just mentioned. Fig. 8 shows a microscopical section
taken 3 ft. from the bottom, and further studies of the figure
reveal in addition to the usual structureless drift, woody and
herbaceous plant fragments, pollen, spores, spicules, etc., all of *
which have been preserved from decay by a perpetual water cover
and natural acidity. It is manifest that this material does not
represent the final stage in the reduction of fibrous peat, but rather
an accumulation of drifted and wind-blown matter which was
precipitated at some time when lacustrine conditions prevailed.
This relation is still more obvious when it is demonstrated to be
similar in the most exacting detail to that already shown to be
characteristic of present lake deposits and illustrated in figs. 1-4.
amorphous mass, there appears a light brown
material
"saw grass"
marshes. Fig. 9 shows photomicrographically the true nature of
the substance. In addition to root fragments across the illustra-
tion, there appears the usual disorganized material, pollen, spores,
and spicules, all of which indicate an allocthonous origin. An even
clearer idea of the lacustrine nature of this peat may be obtained
by reference to fig. 10. In the upper right hand corner of the
figure is a much distorted fragment from some herbaceous plant,
amorphous matter, and ejecta. The most noticeable, as well as
one of the most significant, features, however, is a fern sporangium
and a sponge spicule which could not occur in juxtaposition except
through sedimentation in open water.
Microscopical studies of this vertical series indicate that about
the time when the last of the herbaceous material had been de-
posited, the accumulated mass was above water level, thus furnish-
ing a somewhat drained soil for the grow r th of more woody plants.
Consequently the amphibious species were forced to move on, and
their place w r as taken by woody trees and shrubs. This later
growth in turn built up a layer of autocthonous peat which shows
the remains of comminuted material, but none of the structures
so characteristic of the allocthonous layers below. In securing
these samples some difficulty was experienced in forcing the probing
*
19*73 FORSAITH—ALLOCTHOXOUS PEAT 201
instrument through the tangled cypress logs and roots, which resisted
decay more than the dicotyledonous trunks and settled through
the oozelike mass below. Although these structures are not general
in peat beds, they are by no means uncommon, and in all probabil-
ity have homologues in coal beds, a fact which has led to the idea
that they are indicative of an autocthonous origin for coal. Like
all other megascopic evidence, however, the interpretation of these
structures is open to question, since conditions like those in the bog
just mentioned might have prevailed in the past, and fallen logs
settled through the unresisting lake peats below the growing
stratum.
It must be apparent that allocthonous peats in this region are
vastly predominant over those laid down in place, which is quite
in accord with the statement of Davis (15), namely, "the fact [is]
that at the present time peat deposits of this type [lacustrine] are
numerically more important than any other in regions w r here peat
formation is common." The even more pronounced dearth of
accumulated generations of plants in situ in this region than is usual
in the more northern bogs is without doubt due to climatic condi-
tions, which in w r armer localities are more favorable to the destruc-
tive action of fungi. Since Florida now has a climate similar to
that generally ascribed to the coal-forming periods, it seems logical
to infer that strictly in situ depositions were equally scarce during
ancient times. This phenomenon is well illustrated, in fact, by
several swamps in Florida where the sandy floors do not present
any quantity of autocthonous peat. For example, in an extensive
swamp near Gainesville there appears a dense growth of cypress,
pine, and dicotyledonous trees growing up through an almost
impenetrable tangle of fallen trunks in all stages of decay. One
can hardly imagine a more favorable location for the accumulation
of autocthonous peat, but in spite of this, an examination showed
but a few inches of humus-like substance derived from comminuted
plants.
Although these Florida peats present conditions of environment
more like those which formerly prevailed over the entire earth,
some attention should be paid to the more northern deposits, as in
all discussions of the problem of coal formation, they are mentioned
202 BOTANICAL GAZETTE [march
as the counterpart of "autocthonous" coals. A bog of this type
near Fresh Pond in Cambridge, Massachusetts, will serve as an
example. Samples were taken in the usual way throughout the
entire 30 ft. of the deposit. With the exception of the extreme
upper stratum, the samples present a uniformly brown plastic
consistency, similar to that found in open lakes. A subsequent '
examination revealed that the lower 28 ft. were singularly constant
in respect fro structure, and composed of the usual amorphous
material in which were imbedded pine, larch, and amentiferous
pollen; spores and sporangia of ferns and fungi; vast quantities
of diatomaceous tests and sponge spicules; minute fragments of
roots, stems, and leaves of the higher plants; and animal deriva-
tives such as insect parts, water organisms, and ejecta from aquatic
creatures. All of these structures are very similar to those shown
in figs. 1-4, with the exception of unimportant northern and southern
floral differences. There also appeared in this layer some indica-
tions of carbonized woody fragments which had been washed into
this former lake from a region swept by a prehistoric forest fire,
and there deposited. This fact is significant, since such structures
are of common occurrence in coal sections in juxtaposition with
unburned material, precluding the possibility of deposition in situ
(7) . These inclusions, together with the wonderfully perfect preser-
vation of the debris even in the very lowest strata, dispel any doubt
that it is of an allocthonous origin, and not one brought about by
an accumulation of fallen plants which later decay to a structure-
less mass (the " completely decomposed peat" of many writers).
The next swamp to be considered is a so-called "Sphagnum
bog" in Auburn, New Hampshire. This deposit is found in depres-
sions between long irregular ridges, in the form of the letter Y,
about 2 miles in length and half a mile in breadth. In the cen-
tral portion there occurs a chain of more or less circular ponds sur-
rounded by the usual zones of growth, the inner zone of which is
distinctly sphagnoid. A series of tests showed a layer of lacustrine
peat about 27 ft. in depth. Above this and near the ponds there
is a floating "mat" of Sphagnum and other plants about 1 ft.
in thickness. Back from the shores there appears a tangled mass
of roots and fallen plants above this mossy stratum. Excepting
i9i 7] FORSAITH—ALLOCTHOXOUS PEAT 203
this thin autocthonous deposit, all the microscopical sections showed
a
muck" formed by sedimentation similar in composition to that
already described for the bog in Cambridge and in more south-
ern regions. Material from several lakes in eastern Canada was
-
minutely examined, and structural evidences of allocthonous peat
were found to correspond so closely to those in the United States
that any further discussion of them is unnecessary.
Since the shallow or intermittent lakes are not favorable to an
accumulation of any appreciable amount of peat, owing to periods of
drought and constant agitation by waves, they will receive but
brief consideration. Many of this type were observed around
Zellwood and Lake Tohopikaliga in Florida, and several small
ponds in New Hampshire. In all there was little peat, especially
in the south, where there are distinct wet and dry seasons favoring
the destruction of whatever material may have gathered during
periods of inundation.
There now remains only one distinct kind of fresh water peat to /
nam
:ly, that found in river estuaries. One example
at Pablo Creek near Jacksonville, Florida, will be discussed.
Topography indicates that the space between two elevations was
once occupied bv a river a mile in breadth. This broad stream
6
filled its bed with
r accumulated so t
by an allocthonous layer of peat, excepting the channel of a mean-
dering river. Tests showed a uniform deposit about 12 ft. in depth.
Fig. ii shows
g. n snows tne microsco
)ical character of the material, and
studies of the entire vertical series indicate a general uniformity.
It will be observed that coniferous woody fragments are very
abundant, as indicated by a uniseriate ray in tangential section
and an absence of vessels. There are also present the more evident
lacustrine derivatives, such as a broken sponge spicule, pollen,
amorphous material, and a group of spores. These structure>
indicate that the deposit, like those found in the now open and
filled lakes, has arisen by similar processes of deposition in open
water.
The peat illustrated in fig. 11 is especially favorable for com-
parison with thin sections of the more lignitoid coals (bituminous)
204 BOTAXICAL GAZETTE [march
as shown in fig. 12. This pictures a microscopical section of
bituminous coal from Perry County, Ohio. Crinkled bands of
com
figu
coal are present as flattened spores, appearing as light bodies im-
bedded in a dense black amorphous matrix. Both the lignitic coal
amount
material in addition to the more obviously lacustrine derivatives,
such as spores, etc., which have been shown to be characteristically
amp peats. It seems
must
similar process, and for this reason any coal showing a high spore
content should be considered as having been formed in the same
manner which obtains in present deposits; that is, in open water,
and not by an accumulation of fallen plants in situ, as stated by
the older geological publications upon this subject (1, 5, 11, 14* 1 5)-
Since it is generally admitted that natural factors, such as
climate and topography, have been instrumental in the formation
of our coal beds, it is obvious that a correlation between past and
present phenomena is essential for a precise understanding of ancient
and modern peat deposits. In regard to climate, competent investi-
gators are quite agreed that there was a somewhat warm and humid
atmosphere over the earth during the Carboniferous and later
peat-forming epochs. This supposition is corroborated by obser-
vations of fossil remains characteristic of the different periods which
show a usual lack of annual rings. The nearest parallel to these
climatic conditions of growth is now found to prevail only in semi-
tropical and tropical regions. Because of the importance of these
considerations, the writer has chosen many of his illustrations from
the semitropical peat deposits of Florida, since they present a
closer analogy to coal beds than do the more northern organic
strata. It has already been pointed out that there is a sur-
prising lack of autocthonous accumulations in this locality in
contrast to an abundance of lacustrine deposits. This dearth of
land-formed peat is clearly dependent upon the rapid decay of
exposed land plants in zones without a winter season. Accelerated
disintegration under these conditions is sufficiently pronounced to
1917] FORSAITH— ALLOCTHONOUS PEAT 205
I
prevent any appreciable amassing of vegetable matter other than
that protected by a continuous covering of water. Studies of coal
sections indicate that similar processes were as effectual in the
past, for there is a universal deficiency of strictly autocthonous coals
as revealed by the microscope (8).
Although this prehistoric lycopod flora, growing on the low-
lying shores of ancient lakes, was different from that which now
enters into the formation of peat, the process by which fragmentary
material was derived from this cryptogamic growth was un-
doubtedly the same. Jeffrey (8), as a result of his studies of
sections of coal from all over the world, has found that all categories
from cannel to anthracite show spores of arboreal cryptogams
in varying amounts, just as the peats of today show different pro-
portions of pollen. In addition to the many spores carried into
these carboniferous lagoons by the wind, sluggish streams brought
microscopic debris in all stages of decay. This detritus was pre-
cipitated, and the allocthonous peat was augmented by an age-long
process of sedimentation. A continuance of such conditions
mass
m
swamps. This bog-loving flora did not, however, add in any appre-
ciable degree to the substance already accumulated, owing to their
rapid decay in a fallen state, both as a result of a warm climate and
its less resistant organization. In fact, all microscopical evidence
points to a condition very similar to that already described for
recent peat deposits, the major part of which is quite conclusively
shown to be of drifted derivation.
Another fact which supports the allocthonous theory of coal
formation, is the vast predominance of lacustrine peat over in situ
deposits at the present time. This fact has been well illustrated
by the several strata already mentioned, such as those found in
lakes (swamps), and river estuaries. The phe-
filled
warm
almost
Thus it is apparent that the mode of peat formation, as illus-
trated by its anatomical structure and topographical features, shows
strikingly similar analogies in coal. It must be assumed, therefore,
206 BOTAXICAL GAZETTE [march
that the major part of our coal beds, like peat deposits, does not
represent a gradual accumulation of successive generations of
fallen plants in swamps, but rather a long continued and peaceful
sedimentation of wind-blown and drifted plant fragments and
minute organisms in the depths of open bodies of water.
In conclusion, the writer wishes to express his sincere thanks to
the Committee of Sheldon Traveling Fellowships of Harvard Uni-
versity for the granting of a fellowship, the stipend of which has
made possible these investigations; to Professor R. Thaxter of
Harvard University for samples of peat; and to Professor E. C.
Jeffrey for advice during the course of the work.
Harvard University
LITERATURE CITED
i. Chamberlin, T. C, and Salisbury, R. D., Geology. 3 vols. New
York. 1904-1906.
2. Davis, C. A., The ecology of peat-forming plants in Michigan. Report
Mich. State Geol. Survey. Lansing. 1907.
3. , The uses of peat for fuel and other purposes. U.S. Bur. Mines,
Bull. no. 16, pp. 214. Washington. 1911.
4. Fordyce, W., A history of coal. London, i860.
5. Geikie, A., Textbook of geology. London. 1893.
6. Harper, R. M., Preliminary report on the peat deposits of Florida.
Florida State Geol. Survey, 3d Ann. Rept. pp. 206-375. Tallahassee. 191 1.
7. Jeffrey, E. C., On the composition and qualities of coal. Economic
Geol. 9:730-742. 1914
8. ■, The mode of origin of coal. Jour. Geol. 23:218-230. 191 5.
9. , The nature of some of the supposed algal coals. Ptoc. Amer.
Acad. 46:273-290. 1910.
io- Potoxie, H., Die recenten Kaustobiolithe und ihre Langerstatten. Berlin.
1908.
11. Renault, B., Sur quelques Microorganismes des combustibles fossiles.
Extr. Bull. Soc. Ind. Minerale 14:1-460. 1900.
12. Sanford, S., and Matson, G. C., Geology and ground waters of Florida.
U.S. Geol. Survey, Water Supply Paper no. 319, pp. 50. 1913.
13. Scott, D. H., Studies in fossil botany. London. 1900.
14. Stevenson, J. J., Formation of coal beds. Proc. Amer. Phil. Soc. 50:1-
116, 519-643; 51:423-553; 52:31-162. 1911-1913.
15. White, D., Davis, C. A., and Thiesson, R., The origin of coal. U.S.
Bur. Mines, Bull. no. 38, pp. 390. 1913.
I
1917] FORSAITH—ALLOCTHONOUS PEAT 207
EXPLANATION OF PLATES X AND XI
PLATE X
Fig. i. — Composition of allocthonous peat from Lake Harris in Florida;
grayish background represents amorphous mass of organic derivation in which
there are imbedded abietineous pollen grains, appearing as oblong bodies with
2 laterally attached air sacs; an idioblast from a water lily is pictured in
lower left hand corner as a series of spinelike appendages radiating from a
common center; other inclusions are dense black ejecta from amphibious
animals, and spindle-shaped fresh water sponge spicules.
Fig. 2. — Sample of similar constituents from Lake Dot.
Fig. 3. — Material from Lake Eustis in which there are idioblasts, pollen,
spores, spicules, ejecta, and structureless matter; in upper left hand corner
there appear 3 specimens of the amoeboid Arcella; diatoms of Stauronesis and
Navicula type occur in upper and lower portions of figure respectively.
Fig. 4. — Magnified view of peat from Lake Orange 1 mile off shore; besides
characteristic structures, strips of epidermis and an herbaceous plant fragment
appear, cells of which are still intact.
Fig. 5. — Organization of Kentucky cannel coal, X250; scattered through-
out the section are numerous light bodies, flattened spores of vascular crypto-
gams (homologues of the spores and pollen shown in the illustrations of
allocthonous peat) ; the long grayish bands are indicative of metamorphosed
bits of wood ; separating spores and lignitoid fragments are dense black masses
of organic matter.
Fig. 6. — An herbaceous peat from Lake Orange near shore; fragments of
roots, etc., manifest cell structure clearly; evidences of drifted material are
present, as an idioblast and the mouth part of some insect.
PLATE XI
Fig. 7. — Sample of "saw grass" (Cladium) peat 3 ft. from bottom of a
marsh bordering Lake Harris; exemplifies the usual inclusions characteristic of
allocthonous peat.
Fig. 8. — Preparation of peat 3 ft. from bottom of a bog near Leesburg,
Florida, in which are pollen, spores, spicules, ejecta, and other allocthonous
inclusions; also woody and herbaceous fragments of plants, cells of which i
still intact.
Fig. 9. — Nature of peat above the deep brown plastic layer illustrated
in fig. 8; in addition to usual sedimentary matter, intact fragments of her-
baceous plants may be seen.
Fig. 10. — Another sample from the same horizontal plane with a much
distorted plant fragment in upper right hand corner; below and to left of this,
sponge
Fig. 11.
Jacksonvill
almost entirely composed of lignitoid plant fragments
208
BOTANICAL GAZETTE
[march
origin for this wood is furnished by a uniseriate ray in tangential section and
an absence of vessels; indications for a sedimentary origin for this stratum are
manifest as a sponge spicule, abietineous pollen, and a group of spores in upper
right hand corner.
Fig. 12. — A bituminous coal from Perry County, Ohio, X250; crinkled
bands of compressed wood are especially obvious in upper and left hand parts;
evidences of an allocthonous origin for this coal occur as flattened spores,
appearing as light bodies imbedded in a dense black amorphous matrix.
«
BOTANICAL GAZETTE, LXIII
PLATE X
v. &
I
•
1
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v»
2
n
3
~*~
*- A*-> 4fe
■ \
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5
IORSAITH on PEAT
I
>
/
BOTANICAL GAZETTE, LXIII
PLATE XI
9
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11
12
FORSAITH on PEAT
THE RESPONSE OF PLANTS TO ILLUMINATING GAS
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 227
Sarah L. Doubt
(WITH SIX figures)
Introduction
Owing to increasing loss of plants in greenhouses, and of shade
trees along city streets, it has seemed worth while to work out
simple accurate methods by which gardeners, florists, and forest-
ers may detect gas injury. This study falls into two divisions:
(1) injury to greenhouse plants due to presence of gas in the air;
and (2) injury to trees and bedding plants due to leakage in the soil.
It is hoped that as a result of this work any florist or gardener may
be able to determine readily the presence of illuminating gas in the
air. The presence of gas in the soil as shown by injury to trees is
more difficult to determine.
Considerable work has been done in this laboratory on the
effect of illuminating gas and its various constituents upon plants.
Crocker and Knight (i) showed that the buds and flowers of
carnations are extremely sensitive to traces of illuminating gas
in the air. Three days' exposure, 1 part in 40,000, killed young
buds and prevented the opening of those which already showed the
petals. The flowers were closed by 12 hours' exposure to 1 part
in 80,000. One part ethylene to 1,000,000 parts of air prevented
opening of the buds, and 1 part in 2,000,000 caused the flowers to
close. Their work showed that ethylene is the constituent which
is most toxic to plants. Harvey and Rose (6) showed that the
relatively high toxicity of ethylene holds for many different species
of plants. Crocker, Knight, and Rose (2) found etiolated sweet-
pea seedlings to be extremely sensitive to gas, and suggest the use
of them as test plants for traces of gas. Harvey (8) suggests the
use of the castor bean for the same purpose.
Little is known about the effect of gas on trees. Stone (9)
has made a number of observations in the field, which led him to
209] [Botanical Gazette, vol. 63
2IO
BOTANICAL GAZETTE
[march
many
succumb
to attacks of fungi or of insects. He believes these
secondary causes are often blamed for the total injury.
Rather striking formative effects have been noted by a number
of writers. Stone observed abnormal tissue in the cortex of stems
of Carolina poplar, proliferation tissue in the lenticels of willow,
and increased root development in cuttings of the willow exposed
to gas. Harvey and Rose (6) found that gas and ethylene cause
tubercle-like growths on roots of Catalpa and Ailanthus.
Methods
The gas used in this investigation was that of the Peoples Gas
Company
It averages about 4 per
n monoxide. The ethyl-
from
monox
phuric acid and washed in the usual way. It contained 90 per
cent ethylene and 10 per cent air impurities,
ide was generated from oxalic
acid, washed and analyzed. E;
acid and concentrated sulphuric
ch of these was mixed with air to
same volume nercentaee as exists in illuminatin
mixtures
the illuminatin
&
and the air-gas
gas.
Three general methods of exposing plants to gas were used:
(1) the flowers only were treated with gas; (2) potted plants were
sealed in wardian cases and measured amounts of gas added; and
(3) root systems were treated with a slow stream of gas in the
soil.
1. To determine the limit of toxicity for the flower of the calla
lily (Zantedeschia ethiopicd) the method employed by Crocker
and Knight (i) upon carnations was used. A 20 liter carboy was
inverted over the flower bud and a rubber stopper fitted about
the petiole and made gas-tight with vaseline. Gas was forced
into this 20 liter bottle through a tube inserted in a second hole
in the stopper. A measured amount (800 cc. or 4 per cent) of illu-
minating gas was forced in, and the pinchcock closed. A control
plant was put under identical conditions, except that no gas was
used. When the bottles were removed 11 days later, both flowers
1917] DOUBT— ILLUMINATING GAS 211
opened and were of normal size. The one treated with gas showed
slight discoloration on the spathe. Four per cent of illumina-
ting gas, then, slightly injures the inflorescence of the calla lily.
Further results on the calla lily are given later.
2. Exposure of entire potted plants was made in two wardian
cases (each of about 1000 liters capacity); one case was used for
exposure to gas and the other case was used for the control plants.
The plants were placed in the cases by the removal of a pane of
glass which was later sealed into place with the vaseline-clay
mixture used by Crocker and Knight. The plants were kept
under moisture conditions as nearly optimum as possible. During
the winter season the temperature varied between 15 and 20 C.
with day and night. The experiments were carried on from Jan-
uary to July. In April the temperature became so high in the cases
as to injure the plants. The cases were then given a coat of white-
wash. As the temperature again rose, the cases were moved out-
side and partly shaded. Plants were treated for 2 days, then the
cases were opened, the plants removed, and the cases aired by
means of an electric fan. After watering, the plants were returned
to the case and following renewal of gas were left 2 days more.
They were then removed and the immediate and the after effect
of the gas noted. Since the control plants were in no case injured,
it is clear that the response of the other plants was due to the gas.
Types of responses
1. Leaf fall. — In certain concentrations of ethylene or of illumi-
nating gas, Mimosa, Lycopersicum, Salvia, Datura, Coleus, and
Hibiscus
The
formed. The older the
less gas was required to cause the older leaves to drop. The
youngest leaves were least affected.
2. Rigor.
Mimosa
when subjected to large amounts of gas. Mimosa showed imper-
fect rigor, lost sensitiveness to touch, but was somewhat injured
by the gas. Coleus was completely anesthetized, with no ill after-
effects. Fitting (5) found that heat rigor or rigor from lack of
oxv
212 BOTANICAL GAZETTE [march
by nematodes.
Results of treatments
In the following records, plants are arranged in the order of
their sensitivity to gas. All amounts of gas indicated are in parts
per million of air (ppm) .
Lathyrus odoratus. — With iooo, ioo, 75, and 50 ppm illuminating
gas, the leaves turned yellow and died. Ethylene 8 ppm caused
the leaflets to fall off; 5 ppm caused the leaves to become yellow
and die; 2 ppm caused death of the older leaves; and 0.1 ppm
still caused noticeable injury, although less than in the other cases.
Salvia splendens. — With 25,000 ppm illuminating gas, the older
leaves fell off, while the younger ones showed epinasty; 9000 and
8000 ppm caused epinastic response of the petioles; 1 1000 ppm
1 In all cases of epinasty the leaves drooped, but the blades and petioles remained
rigid. In some cases the halves of the blades folded together somewhat (fig. 4)-
3. Epinasty of petioles. — Suitable concentrations of illuminating
gas and of ethylene produced epinasty in petioles or flower stalks.
In Lycopersicum and Salvia this response is often so marked as to
produce complete spiral coils. The petioles of Ricinus, Datura,
Coleus, and Hibiscus, and the flower stalk of calla lily also showed
epinasty in traces of these gases. The bending may be near the
blade or the bud, as in calla lily leaf and flower; all along the petiole,
as in most younger leaves; or very near the stem, as in most older
petioles (figs. 1-5).
4. Proliferation tissue in lenticels, leaf scars, etc. — In the pres-
ence of traces of illuminating gas or of ethylene, soft spongy tissue
developed in the lenticels (Hibiscus and Sambucus), at leaf scars
(Lycopersicum) , or at more or less extensive regions along the stems.
In the roots of the apple and pear the abnormal tissue developed
just outside the vascular cylinder, but it is not determined whether
it was produced by the cortex or the pericycle. Deep longi-
tudinal cracks developed in the bark of the stem. These appeared
on the apple, pear, ash, and Hibiscus, and to a less degree in Sam-
bucus, Grevillea, and cottonwood.
5. Root tubercles. — Traces of these gases produced tubercle-
like growths on the roots of Grevillea, Sambucus, Populus, apple,
pear, and Hibiscus. In the tomato similar tubercles are produced
1917]
DO UB T—ILL UMINA TING GA S
213
caused the oldest leaves at the base of the stem to fall off and the
younger leaves showed epinasty; 100, 50, and 25 ppm still caused
marked epinasty. With ethylene, 5 ppm caused some leaf fall,
marked, and some petioles showed a com
coil (figs. 3, 4); 2 ppm
o . 1 ppm still caused e
12.5 ppm caused no res
o . 2 and
W
r
1
2
Figs, i, 2. — Fig. 1, Lycopersicum esculent urn: plant at left has been treated for
12 hours with 50 ppm carbon monoxide; plant at right has been treated for 12 hours
with 8 ppm ethylene; the former appears perfectly normal, while the latter shows the
distinct epinastic response characteristic of gas poisoning; note spiral coiling of one
petiole; fig. 2, Lycopersicum esculentum: control at left; plant at right has stood for
1000 ppm illuminating
a few hours longer
would cause leaf fall, but as they stand the leaves show strong epinastic response;
down
Mimosa pudica. 2 — With illuminating gas, 60,000 ppm caused
lm
ppm
vinal
movement; after a day the leaflets turned yellow and fell
off; then some petioles fell; some of the youngest leaves were
2 With Mimosa all amounts of gas used caused the plants to lose their sensitive-
touch. After recovery they regained it.
3 The leaflets folded and the leaves drooped as they do at night or after stimu-
lation, but recover}- was complete after removal.
ness
214 BOTANICAL GAZETTE [march
uninjured. With ethylene, 8 and 5 ppm caused the same response
as the preceding; 2 ppm caused some leaf fall but the injury was less;
0.2 ppm resulted in the fall of a few leaflets, but all leaves showed
sensitiveness by folding together; 0.1 ppm caused some leaflets [
to fall. With carbon monoxide, 50 ppm caused a clear response;
leaflets folded and petioles drooped ; no leaflets fell ; the plant lost
its sensitiveness to touch; recovery was complete after two days
in air.
Ricinus communis* — With illuminating gas, 60,000 ppm caused
imperfect rigor, some leaves falling; 100 ppm caused falling of the
older leaves and epinasty of all others; 50 ppm caused marked
epinasty but no leaf fall. With ethylene, 8 and 5 ppm caused most
of the leaves to fall, the youngest showing epinasty; 2 ppm caused
no leaf to fall, but all the leaves showed epinasty; 0.2 and 0.1
ppm caused a less marked response, but epinasty was still evident
(fig. 5). With carbon monoxide, 50 and 12.5 ppm caused no
response.
Datura Stramonium. — With illuminating gas, 60,000 ppm caused
partial rigor; 4000 ppm caused all the leaves except the youngest *
to fall; 500 ppm caused falling of the oldest leaves; epinasty of
the younger leaves was very similar to that of Ricinus; 50 ppm
caused epinasty of the older leaves. With ethylene, 8 ppm caused
the older leaves to fall, the younger leaves showing epinasty;
5 ppm caused less leaf fall, but the remaining leaves showed epi-
nasty; with 2 ppm there was no leaf fall, but evident epina§ty;
with o . 2 and o . 1 ppm there was evident epinasty. With carbon
monoxide, 50 ppm gave no visible response.
Lycopersicum esculentum. — With illuminating gas, 35.000 ppm
caused the older leaves to fall, the root growth was stimulated on
the stem above the ground, and epinasty occurred; 5 26,000, 1000,
« The epinastic response is very striking in this plant. The cotyledons, leaf blades,
and petioles, all show the characteristic turning. The petioles droop about 90 from
their normal position, so that instead of making an angle of about 45 with the stem
above the leaf, they droop until they make an angle of about 45 with the stem below
the leaf. The blades and petioles are rigid after turning, and usually recover their
normal position after a couple of weeks with no gas present (fig. 5).
* On the older leaves this was near the blade; on the younger leaves it was near
the stem. In some cases this growth caused a spiral coil of the petiole (fig. 1).
1917]
DOUBT— ILLUMINATING GAS
215
75, and 50 ppm caused the same kind of response, but the degree
was lessened somewhat. With ethylene, 8 and 5 ppm caused fall
of the older leaves, the younger leaves showing epinasty (fig. 2),
developed o
this amount
ppm
leaf fall;
response.
ppm
o . 1 ppm caused no
ppm
Coleus sp. — With
no leaves fell, and after removal from the cases recovery was com-
1
•
3
4
Figs. 3, 4. — Fig 3, Salvia splendens: plant at right was treated with 2 ppm ethyl-
ene; after 12 hours it showed distinct epinastic response; plant at left, appearing
normal, received 12.5 ppm carbon monoxide; fig. 4, Salvia splendens: control plant
and one which has been treated for 18 hours in 1000 ppm illuminating gas; epinastic
growth of petioles is clear and leaf blades show a folding together of the sides, which is
characteristic of presence of considerable gas.
plete;
ppm
hours exposure; 6000 ppm caused falling of about half the leaves,
the older being the ones affected;
1000
fall, the younger showed epinasty, and the youngest were unaf-
fected; 100 ppm caused slight epinasty of the younger leaves, and
With ethylene, 5 ppm
this is close to the limit
response
caused the oldest leaves to fall, while the younger, except those at
the tip, showed epinasty; 2 ppm caused no leaf fall, and epinasty
was slight; 0.2 ppm caused no response. With carbon monoxide
12.5 ppm caused no response.
216 BOTANICAL GAZETTE [march
Hibiscus rosa-sinensis. — With illuminating gas, 9000, 8000, and
4000 ppm caused all leaves to fall; new leaves developed in 2-3
weeks after removal from the case; the lenticels on the stem were
filled with spongy white tissue; with 1000 ppm the older leaves
fell, and the younger leaves showed epinasty; with 100 ppm only
slight epinasty was evident. With ethylene, 8 ppm caused dis-
tinct epinasty; 2 ppm caused slight epinasty, but this is near
the limit for response. With carbon monoxide, 12.5 ppm caused
no response.
alypha tricolor. — With illuminating gas, 25,000 ppm
some
ppm
8000 and 1000
Acacia horrida. — With illuminating gas, 8000 ppm caused fall
of many leaves; 1000 ppm caused fall of some leaves several days
after treatment.
Euonymus japonicus. — With illuminating gas, 20,000 ppm
caused most of the leaves to fall; 8000 ppm caused the older
leaves to fall; 1000 ppm caused a few of the older leaves to fall.
Citrus decumana. — With illuminating gas, 20,000 and 8000 ppm
caused most of the leaves to fall after removal from the case;
1000 ppm caused the older leaves to fall.
Zantedeschia ethiopica. — With illuminating gas, 40,000 ppm
caused the flower spathe to become somewhat discolored, but the
plant seemed uninjured; 10,000 ppm caused epinasty in the young
leaves, the petioles being arched next to the blade; 9000, 8000, and
1000 ppm caused the youngest leaf and the peduncle to show
epinasty as above. With ethylene, 5 ppm caused slight epinasty
of the youngest leaf; 2 ppm caused no response.
Pelargonium zonule. — With illuminating gas, 25,000 and 4,000
ppm caused no visible response during 4 days of treatment, but all
leaves fell in 3-6 days after treatment had stopped; 6 100 ppm
caused no response. With ethylene, 8 and 2 ppm caused no
response. With carbon monoxide, 12.5 ppm caused no response.
Begonia luminosa. — With ethylene, 8 ppm caused some epinasty
at the base of the leaf blade. With carbon monoxide, 50 ppm
caused no response.
6 When new leaves developed, they were without the variegated zone.
1917]
DO UB T—ILL UMINA TING GA S
217
I
peciosa. — With illuminat
20,000 ppm caused
some
Populus deltoides.'
000 ppm caused some leaf fall, and
to fall; 8000 ppm caused epinasty.
With illuminating gas, 35,000, 2^.000
other leaves died and fell off;
ppm
Ficus elastica. — With illuminating gas, 20,0c
older leaves to fall during treatment; 8000 ppm <
older leaves to fall about a week after treatment.
Figs. 5, 6. — Fig. 5, Ricinus communis: plant at right, appearing normal, stood
for 2 days in 50 ppm carbon monoxide; plant at left stood in 8 ppm ethyl
for 2
response
note that direction of leaf blades is altered as well as that of petioles; fig. 6, Roots
(Pyrus communis at right; P. Mains at left): the 3-pronged root of pear has had 100
liters of illuminating gas forced into the soil during 40 days; notice swollen condition
of underground parts, also numerous "tubercles"; the root of apple received 160
uminatin
similar to that of pear.
Croton tiglhim var. Sanders.
ppm
illuminating
leaves: 8000
000
000 ppm
slight epinasty.
Tulipa (several varieties). — With illuminating gas, ic
caused injury of the flower buds and the tips of the younger leaves
rolled up; 4000 ppm caused no visible injury.
7 These were cuttings rooted in sand and grown in flower pots.
218 BOTANICAL GAZETTE [march
Hyacinthus (several varieties). — With the same quantities of
illuminating gas, the responses were identical with those of the
tulip.
Carica Papaya. — With illuminating gas, 20,000 ppm caused the
older leaves to fall and the younger leaves to show epinasty.
Caladium esculentum. — This showed no response with 75 ppm
illuminating gas, 8 ppm ethylene, or 50 ppm carbon monoxide.
Lupinus perennis. — This showed no response with 8 ppm
ethylene or 50 ppm carbon monoxide.
Eriobotrya japonica, Phoenix canariensis, Conocephalus sp.,
Canna (King Humbert and other varieties), Achyranthes Lindini,
Cytisus canariensis, and Alternant her a sp. showed no response with
20,000 ppm illuminating gas.
Poly podium, Aspidium, and Asplenium. — With illuminating
gas, 60,000, 8000, and 4000 ppm caused no response.
The preceding data are summarized briefly in table I. The
plants are grouped according to their sensitiveness to gas: very
sensitive, less sensitive, and resistant. The minimum concentra-
tion necessary to produce a response is given in each case.
The following plants showed no response to illuminating gas
or to ethylene in the concentration used: Caladium esculentum,
Lupinus perennis, Eriobotrya japonica, Phoenix canariensis, Con-
ocephalus, sp., Canna, Achyranthes Lindini, Alternanthera sp.,
Cytisus canariensis Poly podium, Aspidium, and Asplenium.
Root treatment of trees
Two or three year old trees were used for the root treatment.
They were treated in flower pots during the winter and early spring,
and then the work was carried on out of doors upon young trees
which had been growing in the soil for a year or more.
The potted plants were set on tripods and glass tubing was run
through the cork plug in the bottom of the pot. Connection was
made with a wash bottle and the rate of gas flow through this
wash bottle was controlled by means of a brass stopcock. The
gas was forced out from the inverted carboys by means of water
from a raised tank. All rubber connections with glass tubing were
as short as possible, gas tight, and the gas w r as "water sealed" in
1917]
DOUBT— ILLUMINATIXG GAS
219
the inverted carboys. By means of the brass stopcocks and glass
tubes drawn out to a fine point in the wash bottles, the rate of flow
of the gas could be regulated at will. To keep the soil from plug-
TABLE I
Plant
Gas used and amount in parts
per million (ppm)
Response
Very sensitive plants
Lathyrus odoratus. .
Salvia splendens. . .
Mimosa pudica ....
Ricinus communis. .
Datura Stramonium
« a
Lycopersicum esculentum
..
a
u
a
Coleus sp
Hibiscus rosa -sinensis ....
Acalypha tricolor
Acacia horrida
Euonymus japonicus
Citrus decumana
Zantedeschia ethiopica . . .
Pelargonium zonale
Begonia luminosa
Fuchsia speciosa
Populus deltoid es
Ficus elastica
Croton tiglium
Tulipa (several vars.) ....
Hyacinthus (several vars.)
Carica Papaya
Illuminating gas, 25
Illuminating gas, 25
Illuminating gas, 50
Illuminating gas, 50
Illuminating gas, 50
Ethylene, o. 1
Illuminating gas, 50
Ethylene, o. 2
Ethylene, o. 1
Leaflets died and fell off
All leaves showed epinasty
Some leaflets fell; others
showed epinasty
Epinasty shown by the leaves
Epinasty shown by the young-
er leaves
Close to the limit for the
response
Epinasty
Epinasty shown by the leaves
No response
Less sensitive plants
Illuminating gas, 100
Illuminating gas, 100
Illuminating gas,
Illuminating gas,
Illuminating gas,
Illuminating gas,
Illuminating gas,
1000
1000
1000
1000
1000
Illuminating gas, 4000
Ethylene, 8
Illuminating
Illuminating
Illuminating
Illuminating
Illuminating
Illuminating
Illuminating
gas,
gas,
gas,
gas,
gas,
gas,
gas,
8000
8000
8000
8000
10,000
10,000
10,000
Slight epinasty shown by the
younger leaves
Epinasty shown by the older
leaves
Epinasty
Some leaves fell
Some leaves fell
Some leaves fell
Youngest leaf arched at the
base of the blade
Leaves fell several days after
treatment
Slight epinasty
Epinasty
Some leaves fell
Some leaves fell
Slight epinasty
Flower buds somewhat injured
Flower buds somewhat injured
Older leaves fell, the younger
showed epinasty.
ging the glass tube inserted in the pot, a small vial with a slit along
the side of the cork was fitted over the end of the tube inside the
melted
flower pot. The pot was then dipped into
to prevent too much escape of gas through the lower part of the pot.
220 BOTANICAL GAZETTE [march
When the trees were treated in the open ground, glass tubes
12-24 inches long, depending upon the size of the trees, were buried
close to the side of the tree. ' The same precaution was used here
to prevent clogging.
The following are the results for each tree or plant treated,
the length of time treated, and the amount of illuminating gas
passed into the soil. In no case could the odor of the gas be
detected on a handful of the soil or escaping in the air. The
temperature range was 12-20 C.
Acer Negundo. — A young tree was treated for 45 days and given
60 liters of gas. There was no visible effect above or below ground.
Acer saccharinum.- — Treated 42 days and given 140 liters of
gas, the parts above ground were unchanged. The stem below
ground, however, was swollen, soft, and cracked longitudinally.
A section showed proliferation tissue produced just outside the
vascular cylinder^
Chrysanthemum hortorum. — One plant, being treated 42 days
and given 80 liters of gas, was killed, no proliferation tissue being
produced or other visible changes. A second plant was treated 28
days and given 60 liters of gas. Some roots grew up out of the
ground, probably due to loss of geotropic response.
Fraxinus americana. — Treated for 42 days and given 120 liters
of gas, the parts above ground were unchanged. Below ground
the stem was swollen, soft, and cracked longitudinally. Sections
showed that abundant proliferation tissue was produced just out-
side the vascular system.
Grevillea robusta. — One specimen was treated 33 days and given
40 liters of gas. After 2 weeks gummy matter exuded from a slight
crack in the stem just above the ground. A second plant was
treated 48 days and given 40 liters of gas; and a third was treated
31 days and given 19 liters of gas. The roots of all three showed
spongy white masses of tissue at short intervals, with no epidermis.
Many roots were dead. The underground parts of the stem were
swollen, due to the development of spongy, white tissue.
Hibiscus rosa-sinensis. — A plant was treated 15 days and given
40 liters of gas. The leaves showed epinasty for 2 days and then
fell off. After 4 days' treatment, white spongy tissue developed
i9i 7] • DOUBT—ILLUMINATING GAS 221
in the lenticels just above ground. The underground parts were
enlarged to three times their normal size. The cortical tissue was
white and spongy. The bark split longitudinally and dropped off.
Small tubercles developed on many roots. The xylem and phloem
appeared normal. These results with Hibiscus agree with those
of Harvey and Rose (6) .
Lycopersicum esculentum. — One plant was treated 24 days and
given 20 liters of gas, while a second plant was treated 18 days and
given 20 liters of gas. After a few hours' treatment, the lower
leaves began to show the epinastic response, falling after 2 days.
Many more roots developed on the stem above ground than on the
control plant. Roots grew up out of the ground, probably due to
loss of geotropic sensitiveness. Tubercles occurred on the roots.
The control plants showed some tubercles, but the number was
greatly increased upon the treated plants. Nematodes were
present in many of these tubercles.
Poa pratensis. — One sod was treated 38 days and given 60
liters of gas; a second 25 days with 60 liters; a third 5 days with
40 liters; and a fourth 8 days with 40 liters. There was no response
in any case.
Populus deltoides. — Treated 81 days and given 60 liters of gas,
the roots developed many small " tubercles," being swollen to
twice the normal size at these points. The tissue was soft and
spongy. The stem showed no visible effect above ground; below
ground it was swollen and rigid,
Pyrus communis. — Treated 40 days and given 100 liters of gas,
there was no visible response above ground, but all underground
parts were swollen. Longitudinal cracks appeared, in which was
soft spongy tissue. All the roots were irregularly enlarged, all the
proliferation tissue being in the cortex (tig. 6) .
Pyrus Malus. — Treated 62 days and given 160 liters of gas, the
response was very similar to that of the pear (fig. 6).
Ricinus communis. — Treated 45 days and given 80 liters of
gas, all leaves except the youngest fell. The underground part
of the stem was swollen and cracked longitudinally.
Salvia splendens. — One plant was treated 18 days and given
20 liters of gas, and another plant was treated 42 days and given
222 BOTANICAL GAZETTE [march
80 liters of gas. Some leaves fell and others showed epinasty;
but the underground parts showed no effect.
Sambucus canadensis. — Treated 60 days and given 60 liters
of gas, the roots were killed. Some roots w r hich were still living
showed " tubercles" similar to those upon Populus. The stem
below ground was somewhat swollen, due to the development of
spongy white tissue in the lenticels.
Ulmus americana. — Treated 9c days and given 180 liters of
gas, after 3 weeks the bark cracked vertically just above the sur-
face of the ground. After 6 weeks, 2 small limbs died and were
removed. About half the leaves fell during the treatment. Near
■
the close of the treatment the underground parts were dead and
cracks extended throughout the bark and cortical tissue. There
was a small amount of proliferation tissue just outside the vascular
system.
Practical suggestions for florists
To detect illuminating gas in a greenhouse, the florist should
provide himself with some vigorous plants of one of the following:
tomato, castor bean, scarlet sage, Jimson weed, or sensitive plant.
These should be grown in pots so that they may readily be handled,
and should have from 6 to 1 2 or more leaves. They must also be
in vigorous condition; otherwise they may not respond should
illuminating gas be present. These should be placed at various
locations throughout the greenhouse and left 24-48 hours with
poor ventilation. All the plants named will respond to traces of
illuminating gas within this period at ordinary temperatures-.
With only a trace of gas present in the air, the epinastic
response of the leaves will be very noticeable if these plants are
compared with normal plants without gas. This bending down
of the leaves will increase with the concentration of the gas present
in the air. All these plants will drop their leaves with a concen-
tration below the limit of the odor of gas. The older leaves fall
first, the younger leaves being retained until there is 1 part of
illuminating gas to 1000 of air.
Summary
1. The following plants are admirably adapted for use as test
plants for illuminating gas in greenhouses: Lycopersicum escu-
i9i 7l DOUBT— ILLUMINATING-GAS 22$
lentum, Salvia splendens, Mimosa pudica, Ricinus communis,
Datura Stramonium, and Dianthus Caryophyllus. The response
of each is definite, striking, and not easily mistaken.
2. Traces of gas (50 ppm of air) cause the epinastic growth of
the petioles of all these plants, with the exception of the last. The
flower buds of the carnations are blighted by these amounts. One
part of illuminating gas per 1000 of air causes leaf fall in the follow-
ing plants: Lycopersicum esculentum, Salvia splendens, Mimosa
pudica, Datura Stramonium , Ricinus communis, Coleus sp., and
Hibiscus rosa-sinensis. Both the amounts (50 ppm of air and
1 part per 1000 of air) are far below the limit of odor. Repeated
trials showed that it was impossible to detect less than 0.25 per
cent of illuminating gas (1 part to 400 of air) by the sense of smell.
3. Amounts of ethylene corresponding to the gas mixture gave
similar responses; 2 ppm of air caused epinastic grow r th of the
petioles of Lycopersicum esculentum, Salvia splendens, Mimosa
pudica, Ricinus communis, and Datura Stramonium; 8 ppm of
air (equivalent to 200 parts of illuminating gas) caused some leaf
fall in the 5 plants named.
4. Poa pratensis and Acer Negundo are very resistant to gas,
having shown no response to concentrations injurious to all other
forms tested.
m
there is enough present to be detected by odor: Caladium escu-
lentum, Lupinus perennis, Eriobotrya japonica, Phoenix canariensis,
Conocephalus sp., Canna, Achyranthes lindini, Alternanthera sp.,
6. The following
the soil: Pvrus Mains
Polypodi
Ulmus
Populus deltoides, and
Catalpa, and Sambucus
of the stems below th
Grevillea robusta, Catalpa speciosa,
ericana. Apple, pear, ash, elm,
Elm, ash, and
iust above the
surface of the ground.
7. The following bedding plants are injured by gas escaping
into the soil: Lycopersicum esculentum, Salvia splendens,* Ricinus
communis, and Chrysanthemum hortorum. Chrysanthemum i-
224 BOTANICAL GAZETTE [march
killed outright; the others drop their leaves or show epinastic
growth of the petioles.
8. Young trees at least are injured by leakage of illuminating
gas too slight to be detected by odor. The foliage shows no injury,
and one would not be likely to suspect gas poisoning from the
appearance of the tree above ground. Judging from my results
with trees, their killing by illuminating gas is a very slow process,
going on for months or years. It is certain that enough gas to
cause an odor in the vicinity of trees would be enough to injure them
seriously.
I am indebted to Dr. William Crocker for suggestions and
help during the progress of the work.
Winona Federated College
Winona Lake, Ind.
7
Harvey, E. M., Some effect
Bot. Gaz. 60:193-214, 191 5.
8.
laboratory air. Bot. Gaz. 56:439-442
1913
9. Stone, G. E., Effect of escaping illuminating gas on trees. Mass. Exper.
Sta. Report pp. 180-185. 1906.
10. , Effects of illuminating gas on vegetation. Mass. Exper. Sta.
Report DD. a v-60. ion.
<
LITERATURE CITED
1. Crocker, Wm., and Knight, L. I., Effect of illuminating gas and ethylene
upon flowering carnations. Box. Gaz. 46:259-276. 1908.
2. Crocker, Wm., Knight, L. I., and Rose, R. C, A delicate seedling test.
Science N.S. 37:390. 1913.
3- , A new method of detecting traces of illuminating gas. Science \
N.S. 31:636. 1910.
*
4« , Effect of various gases and vapors upon the etiolated seedling
of the sweet pea. Science N.S. 31:635-636. 1910.
5- Fitting, Hans, Untersuchungen iiber die vorzeitige Entblatterung von
Bltiten. Jahrb. Wiss. Bot. 49:187-263. 191 1.
6. Harvey, E. M., and Rose, R. C, The effect of illuminating gas on root
systems. Bot. Gaz. 60:27-44. 191 5.
THE SUPPOSED ACTION OF POTASSIUM PERMANGA-
NATE WITH PLANT PEROXIDASES
Herbert H. Bunzell and Heinrich Hasselbring
Reed 1 has recently reported experiments which he believes
throw a new light on the mechanism of oxidation in living tissues.
The experiments relate to the reactions involved in the process of
oxidation by means of peroxidases. To a horseradish extract, which
in itself was incapable of bringing about the oxidation of potassium
iodide or of gum guaiac, he added concentrated potassium per-
manganate solution until the permanganate was no longer reduced.
He then added a small excess of horseradish extract to reduce any
free permanganate present. On filtration a clear, rather deep
yellow solution was obtained, which, when mixed with solutions
of potassium iodide, gum guaiac, or pyrogallol, caused rapid
oxidations of those substances. Reed's interpretation of these
experiments is that the peroxidase of the horseradish extract com-
bines with oxygen from the permanganate, thus forming a new
compound which readily gives up oxygen to other compounds.
He concludes, therefore, that in oxidation processes catalyzed by
peroxidases two reactions are involved: first, a combination of the
peroxidase with oxygen from substances acting as oxygenases;
and second, a transfer of this oxygen to the substances oxidized by
means of peroxidases. Thus he believes the mechanism of oxi-
dation in living tissues is explained.
Contrary to Reed's belief, this interpretation throws no new
*
mechani
Traube
Kastle and Loevenhart. Moreover, since manganese com-
themselves
mixtures
with wjiich he worked to peroxidase activated by ox
postassium permanganate is at least open to questi
x Reed, G. B., The mode of action of plant peroxidases. Box.
1916.
225]
That the
[Botanical Gazette, vol. 63
226 BOTANICAL GAZETTE [march
presence of peroxidases is not necessary to bring about the observed
reactions is shown by the following experiments:
i. Two-tenths of a gram of dried white of egg was dissolved
in 10 cc. of water. To this solution 2 drops of saturated solution
of potassium permanganate were added. The pale brown filtrate
from this mixture gave intense oxidase reactions with guaiac, J
potassium-iodide-starch, and pyrogallol.
2. One gram of Witte's peptone was dissolved in 20 cc. of
water and 5 drops of saturated potassium permanganate solu-
tion were added. With the pale brown filtrate the 3 oxidase
reactions just mentioned were carried out. All were strongly
positive.
3. To about half a gram of tyrosin mixed with water 2 drops
of a 5 per cent solution of potassium permanganate were added.
The brownish mixture gave a clear brown filtrate which oxidized
potassium iodide, guaiac, and pyrogallol.
4. One-half gram of tyrosin was dissolved in hot water. To
the boiling solution 3 drops of a 5 per cent solution of potassium
permanganate were added. The pale brown filtrate from the
mixture gave the 3 oxidase reactions. This filtrate was boiled
and allowed to stand overnight, but no further precipitate was
formed. The filtrate still gave all the oxidase reactions.
5. To a solution of 1 gram of glucose, 2 drops of a saturated
potassium permanganate solution were added. The mixture was
warmed until the purple color had given way to light brown.
The filtrate gave the oxidase reactions distinctly. Fructose treated
in the same way gave strong reactions with guaiac and with
notassium-iodide-starch, but none with pyrogallol.
6. To a boiling solution containing 3 drops of a 5 per cent
potassium permanganate solution in 10 cc. of water, glycerine was
added drop by drop until the purple was replaced by brown. The
filtrate from the brown precipitate was pale straw-colored. It
gave all the oxidase reactions.
7. One cc. of salicylic aldehyde reduced quickly in the cold
2 drops of a 5 per cent solution of potassium permanganate, form-
ing a brown precipitate. The pale straw-colored filtrate gave
reactions with potassium-iodide-starch and with guaiac.
I
L
roi-I BUNZELL & HASSELBRIXG— PEROXIDASES 2 2*]
8. Methyl alcohol and ethyl alcohol when gently warmed
reduced potassium permanganate to a colorless solution, which
when filtered from the brown precipitate gave no oxidase
reactions.
9. Formaldehyde and acetaldehyde reduced potassium per-
manganate in the cold, giving brown or black precipitates and
colorless solutions which gave no oxidase reactions. This result
xpected from
alcohol.
10. A trace of manganese peroxide shaken up in water oxidized
guaiac, potassium iodide (in neutral solution), and pyrogallol.
In all these experiments, a large excess of the organic com-
pounds was used, so that the solutions would be free from potassium
permanganate in the sense in which Reed considered his solutions
free from unreduced potassium permanganate. The potassium
iodide reactions were carried out in solutions of the same strength
as those used by Reed. In all cases the reagents and control
mixtures failed to give the oxidase reactions. The brown filtrates
as well as the colorless ones contained manganese.
It appears from these experiments that in the reduction of
potassium permanganate by organic substances in neutral solu-
mansanese are formed
which
of per-
manganic acid are still capable of carrying out oxidations. When
permanganate
manganese
compounds no longer gives the
oxidation reactions described. By careful reduction both stages
can be obtained with the same compound (glycerine, glucose).
Inasmuch as the brown solutions contain manganese not
reduced to its lowest state of oxidation, and since manganese
peroxide itself brings about the oxidation of guaiac, potassium
iodide, -and pyrogallol, it becomes extremely probable that the
oxidation phenomena observed by Reed were brought about by
peroxides of manganese and not by activated plant peroxidases.
Moreover, since a number of substances acting on potassium per-
manganate give mixtures which oxidize other compounds, there is
no evidence in Reed's experiments that the reduction of the
1
<
228 BOTANICAL GAZETTE [march
potassium permanganate was brought about by plant peroxidases.
His conclusions, therefore, drawn from reactions which are common
to many organic substances and which are not known to be proper-
ties of peroxidases, are too sweeping for the experimental grounds
upon which they are based.
Bureau of Plant Industry
Washington, D.C.
!
>
¥
<
4
I
'
*
LEAF NECTARIES OF GOSSYPIUM
E. L. Reed
(WITH PLATES XII AND XIII AND ONE FIGURE)
■
On the midrib and sometimes on the other principal veins on the
underside of leaves of Gossypium, certain nectar glands are found.
All species of cotton, with the possible exception of G. tomentosum,
w
t
*-.
!
Fig. i.— Nectar gland on a leaf of Gossypium hirsutum
possess these glands, which are usually oval or pear-shaped, some-
times even sagittate in form. Taylor (i) says "these gland
are usually small, rounded, shallow pits, with a floor of round-
topped secreting cells"; and Watt (2) states that "these midrib
lands may be elongated and elevated portions of the veins that
Or
2 29]
Botanical Gazette, vol. 63
230 BOTANICAL GAZETTE [march
become pale colored or assume a pink tinge, and then rupture
lengthwise, or they may be circular or oblong warts which open
into distinct pits." Tre lease (3) points out that the glands begin
to secrete at about the time the seedling has expanded 4 leaves,
and that the nectar is secreted most abundantly at night. Saf-
ford (4) states that "they .... occur on all leaves of cotton
• .... in the form of vagina ted glands." He gives a photograph
by Howard, of the United States Department of Agriculture, of a
cross-section of a nectar gland of the cotton leaf.
The glands described in this paper are from Gossypium hirsutum.
They are oval-shaped depressions, filled with closely crowded
multicellular papillae and surrounded by a thick wall of epidermal
cells (text fig. 1 and fig. 7). In all cases observed the glands
became visible on the cotyledons about the time the first pair of
true leaves developed; they began to secrete a little later. Sections
were made of the cotyledons as soon as they were fully expanded; of
the second and third pair of true leaves at different stages of
development; and also of mature leaves. A section through a
gland of a mature leaf is shown in fig. 7 and one through that of a
young leaf in fig. 9. These glands are of epidermal origin .and
consist of numerous multicellular papillae (text fig. 1). Their
organogeny is as follows:
The epidermal cells from which the glands arise cease to develop
normally and become papillate (fig. 1). The papillae are next cut
off by transverse walls (fig. 2) . The cells thus formed divide again
in the same plane; this may be repeated once or twice, and results
in the formation of short pedestals consisting of 2, 3, or 4 cells
(figs. 3-6). The terminal cell of each papilla then divides by a
vertical wall into two (fig. 10). These in turn divide by walls at
right angles to the first cross wall into 4 cells (fig. 10). The latter
divide by periclinal walls into 4 central and 4 peripheral cells
(fig. 1 1) . Lastly, each of the external cells divides by a wall at right
angles to the surface, and thus a peripheral layer of 8 cells is formed
(fig. 12). The development of the papillae of these glands bears a
remarkable resemblance to that of the antheridia of Riccia (5).
College Station
Texas
BOTANICAL GAZETTE, LXIII
PLATE XI I
>
REKD on LEAK NECTARIES
BOTANICAL GAZETTE, LXIII
PLATE XIII
REED on LEAF NECTARIES
*
1917]
REED— LEAF NECTARIES
23 1
LITERATURE CITED
J
Bull. no. 131, Part V, Bur.
Plant Ind., U.S. Dept. Agric.
Watt, George, Wild and cul
3. Trelease, William, Nectar, its nature, occurrence, and uses. Published
John
W. Edwin
5. Campbell, D. H., Mosses and ferns.
EXPLANATION OF PLATES XII and XIII
PLATE XII
Fig. 1. — From transverse section of leaf showing papillate cell.
Fig. 2. — First cell of pedestal cut off by cross wall.
Figs. 3, 4, 5, 6.— Multicellular papillae showing pedestals with varying
number of cells.
PLATE XIII
Fig. 7. — Vertical section through gland near one end showing papillae
and elongated cells; some of the latter have divided horizontally, and have
formed the wall of the gland.
Fig. 8. — Vertical section through young gland showing first stage in
formation of wall (right side of figure) .
Fig. 9. — Vertical section through midrib showing young papillae.
Fig. 10. — Cross-section of several papillae showing first and second
vertical division.
Fig. 11. — Cross-section of papilla showing periclinal walls.
Fig.
12.
Cross-section of mature papilla showing divisions subsequent to
those shown in fig.
11.
THE REACTION OF PLANT PROTOPLASM
x\, R. Haas
most im
metabolism. It is not, however, the apparent reaction (or total
im
the actual reaction, as shown by the gas chain or by indicators.
The total acidity includes both undissociated and dissociated acid,
while the actual reaction depends only upon the latter.
In the case of a buffer solution 1 the total acidity may be very
high, while the actual acidity may be very low. The higher the
total acidity in this case the more difficult it becomes to change
the actual reaction by the addition of acid or alkali. This applies
to protoplasm, w r hich always has the properties of a buffer solution
(since it contains carbonates, phosphates, proteins, etc.). Hence
asm
may
actual acidity.
So far as the writer is aware, no determinations of the actual
reaction of plant protoplasm have been made by means of the gas
chain (except a single determination of pineapple juice made by
Reed 2 ). Only a few determinations have ever been made 3
means of indicators.
6
number
some
their unusual acidity.
cms
determine the acidity of the iuice bv means
The gas chain used was essentially the form described by
HlLDEBRAND
Chemie
Berlin. 19 14.
2 Unpublished results.
* Cf. Friedenthal, H., Zeit. Ailg. Physiol. 1 .-56. 1902. It is not known whether
in these experiments the proper precautions were taken to crush all the cells and to
secure plant juices which had as high an acidity as the cell contents.
4 Hildebraxd, J. H., Jour. Amer. Chem. Soc. 35:869. 1913.
Botanical Gazette, vol. 63] * [232
<
1917]
HA A S—PROTOPLA SM
233
method
tance.
M
6
crushed
which is first expressed contains a much lower concentration of
electrolytes than that which is obtained when greater pressure is
crush more
It is obvious that when
pressure is first applied and sap is squeezed out through the intact
plasma membrane, the electrolytes may largely be retained within
the cell because they are not able to pass freely through the
membrane. It is desirable, therefore, to grind the tissue and
rupture all of the cells. This was accomplished by thoroughly
grinding the tissue in a mortar. Only a little tissue was ground
at a time, and the grinding was continued until microscopic
examination showed that all the cells were ruptured.
TABLE I
I
Material
Actual acidity
of CO*-free undiluted
juice as determined
by tbe gas chain
Total acidity as
determined by ordinary
titration methods
Lemon (fruit)
Cranberries (fruit), fresh material, peeled
and unpeeled
Grapefruit (fruit)
Apple (fruit)
basal part
Rhubarb (leaf-stalk)^ hltermedi f t K e {*"*•■ "
v '* green part below\
leaf blade /" '
Orange (fruit)
Pineapple (ripe fruit), juice standing 2
hours
Pineapple (ripe fruit), fresh juice
Green pepper (fruit)
Eggplant (fruit)
0.006N
0.004N
0.001N
0.0004N
0.0007N
0.0005N
0.00022N
0.00016N
0.00009X
0.000035X
o 000003 8X
0.000002N
0.9172X (ripe fruit)
o . 3 i94N\ (overripe,
o.3493N/soft fruit)
o. 1927X
O.071 iX
0.1578*
0.1681X
0.0941X
0.1377X
determining
means
>nt of hydrogen. The results of the deter-
minations are given in table I. The results in all cases represent
the average of two or more closely concordant determinations.
Mameu
6
Marie, C. H., and Gatix, C. L., Determinations cryoscopiques effectives sur
des sues veggtaux. 1912.
Dixon
234 BOTANICAL GAZETTE [march
The figures of the table show that the actual acidity bears no
fixed relation to the total acidity, and that great variations are to
-
be found in different plants, as well as in different tissues of the
same plant.
The figures for actual acidity are surprisingly high in the case
of the lemon and of the cranberry, especially in view of the
prevalent opinion that protoplasm demands a neutral or nearly
neutral reaction for normal metabolism. It is of interest, there-
fore, to inquire whether the figures represent the actual acidity of
the protoplasm. In the lemon the acid juice is contained in sacs,
the walls of which are composed of living cells, while the cavity is
produced by the disintegration of cells. Reed 8 has shown that
the living cells of the walls contain oxidases whose activity is
promptly inhibited by the acid contained in the cavity of the sac.
Since the oxidases are active in the living cells, it follows that the
protoplasm is by no means as acid as the juice in the sacs, and
hence the figures given in table I cannot apply to the protoplasm
in the case of the lemon.
With the cranberry the case seems to be different. In this
fruit there are no sacs such as are found in the lemon; the juice is
contained entirely in the cells. It is important, therefore, to
ascertain whether these cells are dead or alive. In order to test
this, the outer colored layer of cells was removed and the following
results were obtained on the colorless cells:
Eosin failed to penetrate unboiled peeled cranberries, but
penetrated readily into the boiled peeled cranberries. The diffi-
culty due to the precipitation of eosin in acid solutions was obvi-
ated by frequent renewal of the eosin solution.
2. Ripe cranberries can be peeled without staining the white
tissue beneath, while this is not possible in overripe, soft
cranberries.
3. Unboiled, peeled cranberries in a red watery extract of cran-
berry peeling were unstained after several hours, while the indicator
readily penetrated the boiled peeled cranberries.
All these tests go to show that the living cells of the cranberry
have an actual acidity which is extremely high. It is quite pos-
8 Reed, G. B., Box. Gaz. 57:528. 1914.
1
IQI?]
HA A S—PRO TOP LA SM
235
sible, however, that the acid sap is contained in vacuoles rather
than imbibed in the protoplasm proper.
Summary
1. The actual acidity and the total acidity of a number of
plant tissues were determined.
t
2. There is no constant relation between the two, but great
variations occur in different plants and in different parts of the
same plant.
3. In one case (cranberry fruits) the surprisingly high actual
acidity of o . 004N (as determined by the gas chain) was found in
the living cells.
Laboratory of Plant Physiology
Harvard University
BRIEFER ARTICLES
A FREEZING DEVICE FOR THE ROTARY MICROTOME
(with one figure)
A few years ago Osterhout 1 figured and published an account of a
simple freezing device to be used in connection with various sorts of
sliding microtomes. Later 2 he published an account of a simple freezing
microtome in which he made use of a knife of a plane for cutting on
account of its rigidity. In each of these devices, the freezing chambers
being stationary, they are both adaptable to the use of brine, carbon
dioxide, or other substances for freezing. These devices have been of
considerable service in the preparation of sections of living tissues.
However, if one wishes sections in large quantity and of uniform thick-
ness, and particularly if thin sections are desired, it is found that a
sliding microtome of almost any construction is inadequate, and to
manipulate it requires considerable dexterity.
It occurred to the writer that the Osterhout apparatus for freezing
with brine might be modified in such a way as to make it usable with a
rotary microtome of any make, and thereby increase its efficiency and
enlarge the usefulness of both pieces of apparatus. The adaptation was
made and the results have proven so satisfactory that a brief account
of the apparatus seems desirable.
The accompanying photograph of the apparatus will serve as a basis
for the description. It is simple and easy to construct, consisting of a
2X10 board 3.5 ft. long for the base, and 2 upright pieces fastened at
the base and braced by a cross-piece about one-third of the distance up.
A bolt passes through the base and the center of the cross-piece, and
another through the upright pieces just above the cross-piece to make
the apparatus firm. The upright has been lengthened in this case to
receive larger receptacles than were originally used. The wheel is 20
inches in diameter and 1 . 5 inches thick, making the whole device about
5 ft. high. The wire to hold the pails is firmly fastened in the middle
to the grooved wheel. The rubber tubing is of stiff white rubber. When
1 Osterhout, W. J. V., A simple freezing device. Bot. Gaz. 21:195-201. figs. 6.
1896.
, Univ. Calif. Publ. Bot. 2:73. 1904.
Botanical Gazette, vol. 63] ■
[236
'.♦
►
1917]
BRIEFER ARTICLES
237
to
P
Fig. 1
238 BOTANICAL GAZETTE [march
the freezing mixture is put in, the 2 pails should balance. An important
though simple detail is the proper adjustment of the brace to hold one
of the pails up until the water runs through the tubes and freezing box
into the other pail. This, as is shown in the accompanying illustration,
is made of a piece of hard wood about o. 75 inch square, fastened at the
upper end to the wheel by a heavy screw, the hole in the brace being
large enough so that it may move freely. The brace must be long
enough for its lower end to rest on the cross bar when the lower pail
is kbout 3 inches above the base board. When the lower pail receives
over half of the water it will move slowly to the base board, the lower
end of the brace will pass over the cross bolt and hang perpendicularly
by the side of the higher pail. As soon as this pail is emptied it should
be lowered, and this should be attended to with promptness, for it is
necessary that the water be kept in constant circulation to obtain the
maximum freezing efficiency.
. A very important part of the apparatus of course is the freezing
chamber. This will have to be made to order to fit the particular micro-
tome one is using, and the size depends upon one's needs. The one
which seems to be of general use and which is employed by the writer is
constructed as follows: A rod of brass about 2 . 25 inches long is hollowed
out about 1 inch deep for the chamber, leaving walls thick enough so
that a firm cap can be screwed on. The other end of the rod is trimmed
down, making a stem of the desired size to fit the particular microtome.
Two tubes with inside diameters 7-8 mm. and o. 75 inch long are welded
into the chamber a few millimeters apart on one side. The faucets,
one in each pail, should be large enough for a free flow of the water into
the tubes and should be shielded on the inside of the pail by copper
gauze. A second faucet should be put into one pail to be used to
remove surplus water.
The freezing chamber, of course, must be in a horizontal position
while the object is being frozen. A half gallon bottle with a hole in the
cork large enough to receive the stem as shown in the illustration is very
convenient.
It is highly desirable to have a section collector if one is cutting
much material. This may be made of a block of wood about 1 inch thick,
hollowed out on one side, leaving enough margin on 3 edges around the
cavity so that it will fit snugly against the knife, a little vaseline being
used to prevent leaking. The box may be clamped on in various ways.
th
they
'
1917] BRIEFER ARTICLES 239
by removing the knife carrier and all attached thereto from the remain-
der of the machine. Gum arabic of medium consistency is used to
freeze the objects in. A layer 2-3 mm. thick should be frozen on the
chamber before placing the object on for cutting. By this means it is
possible to obtain a large number of sections in a very short time, greatly
facilitating the study of algae, fungi, and other soft tissues of either
plants or animals in which only cell forms and cell relations are being
studied. Likewise it is exceedingly useful in preparing cross and
longitudinal sections of leaves, soft stems, etc., for class use. It is also
inexpensive. One can run the machine 8 hours with no difficulty on
40 lbs. of ice.
In orienting the material for cutting, 2 methods may be followed.
Segments of the material may be piled on top of each other on the
freezing chamber and covered with gum arabic and frozen. After trim-
ming to the desired form the material may then be removed, properly
oriented, and quickly refrozen to the chamber. This is desirable only
in cases in which the material is too delicate to stand on end or on edge
if cross-sections are to be made. In the other method one takes the
material, for example, segments of leaves a few millimeters long, dampens
them in gum arabic, and piles them one upon another on a knife blade,
after which the whole pile is tipped over onto smooth frozen gum on the
freezing chamber. With a little care the whole pile may be made to
stand on edge and may be frozen in position for cutting cross-sections.
N. L. Gardner, University of California.
CURRENT LITERATURE
-
^ NOTES FOR STUDENTS
Phenomena of parasitism. — Two further contributions to a series of
studies begun by Brown 1 on the parasitism of Botrytis cinerea have appeared.
In the first of these, Blackman and Welsford 2 describe the microscopical
details of the process of penetration of the cuticle by the germ tubes; in the
second, Brown 3 deals more specifically than in his former paper with the
action on the cuticle of extracts and exudates of the germ tubes.
Blackman and Welsford observed in the earliest stages of penetration
a slight indentation of the outer epidermal wall as a result of the action of the
germ tube, which is held fast to the cuticle by a mucilaginous sheath whose
presence was made evident by means of a suspension of silver particles. The
actual penetration of the cuticle is accomplished by a narrow peglike out-
growth from the tip of the germ tube. No swelling of the cuticle or of the sub-
cuticular layers previous to penetration was observed, and in no case was
an injury to the epidermal cells or subepidermal cells apparent before the
breaking of the cuticle. Soon after the penetration of the epidermis, the cells
of the palisade layer begin to disintegrate, and with the advance of the hypha
the cells of the spongy parenchyma also are killed. The toxic action of the
fungus extends considerably beyond the region actually invaded. After a
portion of the leaf tissue had been killed, other hyphae were observed to pene-
trate through the stomata, probably as a result of the diffusion of food sub-
stances from the dead cells, for primary infection though a stomate was
never seen.
From their observations the authors conclude that the cuticle is ruptured
by mechanical pressure exerted by the germ tube and not by the solvent action
of any substance secreted by it. They believe that the germ tube is enabled
to exert the pressure necessary for the indentation of the cell wall and pene-
tration of the cuticle by virtue of the gelatinuous sheath which holds the germ
tube in place. It is not clear, however, how the germ tube is thus enabled to
bring about an indentation of the cell wall over an area more extensive than *
that covered by the tip of the tube itself, as shown in some cases (notably
1 Rev. Bot. Gaz. 61:79. 1916.
2 Blackman, V. H., and Welsford, E. J., Studies in the physiology of parasitism.
II. Infection by Botrytis cinerea. Ann. Botany 30:389-398. pi. 10. figs. 2. 1916.
* Brown, Wm., Studies in the physiology of parasitism. III. On the relation
between the infection drop and the underlying host tissue. Ann. Botany 30:399-406-
1916.
240
I
1917] CURRENT LITERATURE 241
r
fig. 8). It appears not improbable that these may be accidental depressions,
for in many cases of actual penetration figured such indentations are not
evident.
In the study of the action on the cuticle of extracts and exudates of germ
tubes, Brown found that when the extract of germ tubes was placed in con-
siderable quantity on intact leaves and petals of Viola, Petunia, Dahlia, Vicia
Faba, and Begonia her aclae folia, no effect was produced; but in experiments
with Tropaeolum, Geranium, Rosa, and Fuchsia a varying number of discolored
spots appeared on the surfaces covered by the drops. The action in these
cases was attributed to possible wounds in the cuticle. All the extracts were
tested also on wounded leaves and petals, and in those cases in which no action
was observed, the corresponding experiments on uninjured leaves and petals
were rejected. Thus conclusions were drawn only from extracts known to be
active.
When spores were sown in drops of liquid on the surface of leaves, the dis-
coloration appeared first around the margin of the drops where the spores
germinated earliest. When such drops, containing germinating spores, were
displaced slightly on the leaf, the discoloration due to the action of the spores
appeared within the area originally outlined by the drop and none in the new
area occupied. Infection drops cleared of spores had no action on the most
sensitive petals.
With reference to the possibility of the production of oxalic acid in suffi-
cient quantity to cause the death of tissues under the uninjured cuticle, Brown
found that solutions of n/40 oxalic acid and of n/20 potassium oxalate placed
on the leaves had no effect within a period of 1 2 hours, the time required for the
germinating spores to produce discoloration. The maximum concentration
in the infection drops, it was shown, could not exceed n/800.
These experiments seem to show quite clearly that cuticle-dissolving sub-
stances are not present in the extracts made from germ tubes of Botrytis
cinerea, and that such substances, if they exist, do not diffuse into the surround-
ing medium to any considerable extent. The conclusion that chemical action
is entirely excluded seems somewhat too sweeping, however, for there still
remains the possibility of such action at the point of contact of the germ tube
with the cuticle by substances which cannot be obtained in extracts in an active
state. The possibility that oxalic acid occurs in sufficient quantities to injure
cells through the cuticle seems to be definitely excluded.
The observation that the germ tubes of Botrytis cinerea exude no substances
which are capable of diffusing through the cuticle and killing the cells below
corroborates the histological study of Blackmax and Welsfokd, according to
which the cells underlying the cuticle are not injured before the cuticle has
been perforated. In this respect, the behavior of Botrytis cinerea differs from
that of Sclerotica Libertiana, in which DeBary observed a killing of the host
cells before penetration of the cuticle.— H. Hasselbrixg.
242 BOTANICAL GAZETTE [march
Leaf size in plant geography. — Rauskiaer, 4 whose name is associated
with the system of biological types or life forms, has recently submitted another
means of quantitative estimation, so far as the unit chosen is a recorder of the
biological value of a climate. He regards the size of the leaf as the outstand-
ing character, and using the simple leaf as a standard, has proposed a system
of leaf classes (Bladst^rrelsesklasser). In the plan submitted there are 6
different classes or divisions: (i) leptophyll, 25 sq. mm.; (2) nanophyll, • «
9X25 = 225 sq. mm.; (3) microphyll, 9^25 = 2025 sq. mm.; (4) mesophyll,
9^X25 = 18225 sq. mm.; (5) macrophyll, 9^X25 = 164025 sq. mm.; (6) mega-
phyll, which is limited by the upper limit of macrophylls. Originally he
planned to use the number 10 with 25, but from a large number of trials, both
by himself and several of his colleagues, 9 was found to give a better differ-
entiation. In using 9, it is easy to make subdivisions, large, medium, and
small, if desired. Raunkiaer is of the opinion that it is an easy matter to
place the various leaves in their right classes, but in order to facilitate matters,
a graphical representation of the various limits of surface area is pictured,
and by the use of this scheme the leaves may be correctly grouped. Thus, if
a leaf has an area which is less than 25 sq. mm., it is a leptophyll; if larger
than 25 sq. mm. but smaller than 225 sq. mm., it is a nanophyll, and so on.
In using such a method, Raunkiaer contends that it is possible to obtain
the biological factor for climate as far as it influences leaf size. By the use of
such a scheme, comparisons may be made readily between two climates which
have varying effects. One may compare formations which vary at different
points, and also determine the relation between a series of associations which
are somewhat similar. To prove his point he has selected and analyzed
several European evergreen shrub formations.
He suggests that the leaf "size classes" are not the only quantitative units
to be employed, but shows that these units lend themselves rather readily to
the statistical method. A system which would in some way estimate such
structural features as stomatal protection, stomatal opening, or hairiness,
would also give significant results. The difficulties would naturally be many,
but they should not hinder the attempt.
Ecologists and physiologists no doubt will be in hearty sympathy with
Raunkiaer's move in placing ecology upon a basis that is at least somewhat
quantitative. We all are in accord with his concluding sentence (translated
somewhat literally): "by such means only will it be possible to pass beyond
the tourist plant geographer's superficial and vague determinations." — A. L.
BakkeJ
Mountain grassland. — Many of the valleys of the Colorado Rocky Moun-
tains have their comparatively level floors covered with grasslands of somewhat
« Raunkiaer, C, Om Bladst0rrelsens Anvendelse i den biologiske Plante-
geografi. Botanisk Tidsskrift 34:225-240. 1916.
*
1917] CURRENT LITERATURE 243
varied types, presenting ecological problems of peculiar interest. The more
xerophytic type of such grassland has been studied in South Boulder Park by
Ramaley 5 and by him designated "dry grasslands' ' in contrast to the more
mesophytic "meadow." One of the most interesting problems of the park is
the relationship of these two phases of grassland, and one must regret that it
has been so slightly touched upon in the present paper. Another deficiency
is the limited number of data regarding the environmental factors. Some soil
moisture studies seem to show that the growth water is not abundant in any
association, although unfortunately the relationship of the soils of which wilting
coefficient determinations were made and those whose water content were
studied is not clearly apparent. Wilting coefficients ranging from 3.5 to 7.6
indicate to some extent the coarse texture and low water-retaining power of the
soil which, combined w r ith such climatic factors as short summers, high winds,
and an annual rainfall of 28 inches, tend to retard the development of meso-
phytic vegetation.
A most interesting seasonal succession is described, ranging from a pre-
vernal period extending from May 1 to June 15 and characterized by the bloom-
ing of Mertensia Bakeri and Thlaspi purpurascens, through well marked vernal,
early and late aestival, to an autumnal in which the bloom is almost entirely
limited to late grasses and blue gentian.
The series of associations involved in the xerarch succession here in progress
proceeds from one characterized by Erigeron multifidus and Selaginella densa
on recently exposed soil, through others in which Carex stenophylla associated
with certain Leguminosae and Compositae such as Aragallus Lambertii and
Chrysopsis villosa gradually give place to others in which grasses become
increasingly abundant and important. The author regards the ultimate
grassland vegetation as an association in which the grasses represented by
Muhlenh
Whether
this will pass eventually to the more mesophytic meadow, and it in turn be
replaced by forest, seems at present to be a probability not demonstrated. In
spite of this and other unsolved problems, the present discussion, together with
the careful analyses of the same author 6 previously published, very greatly
advances our knowledge of these interesting grasslands.— Geo. D. Fuller.
Taxonomic notes. — Berry 7 has described a new species of Zamia (Z.
mississippiensis) from the Lower Eocene of Missisippi. It has "slender,
graceful leaves and much reduced oinnules suggestive of Z. floridana"
« Ramaley, F., Dry grasslands of high mountain park in northern Colorado.
Plant World 19:249-270. figs. 6. 1916.
, The relative importance of different species in a mountain grass-land.
# - —
Bot. Gaz. 60:154-157. 1915.
grassland. Bot. Gaz. 62:70-74. 1916.
^ Berry, E. W., A Zamia from the Lower Eocene. Torreya 16:177-179-
mountain
?■
244 BOTAXICAL GAZETTE [march
Blake, 8 in "A revision of the genus Poly gala in Mexico, Central America,
and the West Indies/' recognizes 137 species, 39 of which are described as new.
There are also numerous new combinations and new names, and a general
reorganization of the classification.
Brixton, 9 in connection with an account of the vegetation of "the little
known island of Anegada," one of the Virgin Islands, has described a new
Acacia {A. anegadensis) and a new lichen (Arthonia anegadensis).
Britton, 10 in his eighth paper on West Indian plants, describes a new
Cy perns from Jamaica; lists the West Indian species (16) of Stenophyllus,
including a new species; lists the Cuban species (15) of Galactia, with 4 new
species; lists the Cuban species (5) of Machaonia, with 2 new species; presents
the Cuban genus Heptanthus, recognizing 6 species, 5 of which are new; and
publishes 5 new species from Porto Rico, 9 new species from Cuba, and 21 new
species from the Isle of Pines, by several specialists.
Burt, 11 in continuing his studies of North American Thelephoraceae,
has monographed the genus Hypochnus, recognizing 31 species, 13 of which
are new species, and 12 are new combinations.
Burt, 12 in his seventh paper on the Thelephoraceae of North America,
presents the genus Septobasidium. It does not belong to the Thelephoraceae,
because its basidia are not simple, but it is included "merely for the con-
venience of students of the Thelephoraceae." The North American forms
include 17 species, 10 of which are described as new.
Christensen 13 has described a new genus (Maxonia) of ferns founded
on Dicksonia apiifolia Swartz. The species (M. apiifolia) is represented by
specimens from Jamaica and Cuba, while a variety (M . apiifolia duale) occurs
in Guatemala, and is Nephr odium duale Donn. Smith.
Dixon 14 has reported upon a collection of mosses from Borneo, showing
that our knowledge of the moss flora of the tropics is comparatively meager.
The list includes 133 species, 13 of which are described as new. Attention is
called especially to the "peculiar ecological distribution of the remarkable and
striking genera Syrrhopodon and Calymperes." — J, M. C.
8 Blake, S. F., Contrib. Gray Herb. no. 47. pp. 122. pis. 2. 1916.
•Britton, N. L., The vegetation of Anegada. Mem. N.Y. Bot. Gard. 6:565-
580. 1916.
— , Studies of West Indian plants. VIII. Bull. Torr. Bot. Club 43:441-
469. 1916.
11 Burt, E. A., The Thelephoraceae of North America. VI. Ann. Mo. Bot. Gard.
3:203-241. 1916.
13 , The Thelephoraceae of North America VII. Ann. Mo. Bot. Gard.
3:3i9-343- figs- *4- 1916.
13 Christensen, Carl, Maxonia, a new genus of tropical American ferns. Smiths.
Miscell. Coll. 66: no. 9. pp. 4. 19 16.
x * Dixon, H. N., On a collection of Bornean mosses made by the Rev. C. H.
B instead. Jour. Linn. Soc. Bot. 43 : 291-323. pis. 26, 27. 1916.
■a
19*7] CURRENT LITERATURE 245
*-
Mosaic disease of tobacco. — Allard 15 has recently presented good evi-
dence to combat the theory of Woods and of Heintzel that oxidases are
responsible for the mosaic disease of tobacco, in which he showed that the
disease was dependent upon a specific infection. A more recent paper by
Allard 16 describes in detail a study of the properties of the so-called "virus"
of the mosaic disease of tobacco. Healthy plants were inoculated with the
virus after filtration through a Livingston atmometer porous cup, after fil-
tration through powdered talc, after precipitation with ethyl alcohol, after
treatment with formaldehyde, with hydrogen peroxide, with precipitates of
aluminum and nickel hydroxides, and after subjecting the virus to high and
low temperatures. Plants were inoculated also with water extracts of the
dried mosaic tobacco, made after extracting with ether, chloroform, and other
solvents. The infectious principle was retained by filtration through Living-
ston atmometer porous cups and by powdered talc, although the filtrates
gave intense peroxidase reactions. Alcoholic solutions of 75-80 per cent
destroyed the infective principle, while 45-50 per cent solutions did not, but
carried down the infectious principle with the precipitate. Virus treated
with one part formaldehyde in 800-1500 parts of solution gave an infection.
Stronger solutions gave no infection, although they still gave strong
peroxidase reactions. Ether, chloroform, carbon tetrachloride, toluene, and
acetone failed to extract either the infective principle or the peroxidase
from dried material. The virus was killed at temperatures near ioo° C,
but when subjected to a temperature of — 180 C. for 15 minutes it was
not weakened. In every case controls were carried out with tap water and
with the untreated virus. From the results the author concludes that
neither enzymes nor the constituents of healthy sap can be responsible for the
disease, and that since the pathogenic agent is highly infectious and capable
of increasing definitely, there is every reason to believe that it is an ultra-
microscopic parasite of some kind. — H. R. Kraybill.
Fossil Osmundaceae — Kidston and Gwynne-Vaughan 17 have described
three species of fossil Osmundaceae, two of which are respectively from the
Tertiary of Spitzbergen and of Queensland. Another species, Osmimditcs
Carnieri, between the Tertiary and Jurassic of the Andes of Paraguay, is most
interesting. The authors add something to the original descriptions of Schus-
ter from whom they received their material. The stem unfortunately is not
well preserved, but the endodermis frequently joins around the margins of the
leaf gaps, and an internal phloem was also probably originally present. The
Allard
U.S. Dept. Agric. Bull. 40.
1914.
i6
virus
Jour
Agric. Research 6:649-674. 1916.
■» Kidston, R., and Gwyxne-Vaughax, D. T., On the fossil Osmundaceae.
Part V. Trans. Roy. Soc. Edinburgh 50:460-480. ph. 4^44- i9 l6 -
I
246 BOTANICAL GAZETTE [march
stem strongly resembles that of Osmundites skidegatensis from the western
coast of Canada (Lower Cretaceous).
In a second paper, Gwynxe-Vaughan 18 has described the effect of injury
on a narrow stele of Osmnnda regalis. Tracheids appear in the central region
of the stele. The author regards this as evidence of the stelar origin of the
pith in the Osmundaceae. The voluntary blindness of British anatomists as
regards medullary structures is an interesting phenomenon. They welcome
the small amount of evidence which can be brought forward for the stelar
origin of the pith, and close their eyes to the overwhelming evidence for its
derivation from the fundamental system of tissues. The equitable procedure
seems to give the same value to both kinds of evidence, and decides the ques-
tion on the quantitative basis. We may record here the regret that American
anatomists all feel for the untimely death of the junior author Gwynne-
Vaughan, whose published work is of such promise. An appreciative obituary
has recently been published by Scott in the Annals of Botany, — E. C. Jeffrey.
Monomelic capsules in Bursa. — The reviewer has shown 19 that the tri-
angular capsule of Bursa bursa-pastoris is produced independently by two dis-
tinct Mendelian factors (dimery), and has expressed the view (1914) that this
is a derivative condition, the original form of this species probably having had
only one of these factors. A considerable number of wild plants have been
investigated, but as yet only one specimen has been found by the reviewer
which had but one of the capsule factors, this case being still unpublished.
Dahlgren 20 has investigated a plant of this species growing in the botanical
garden at Upsala, and secured from a cross with B. Heegeri (which lacks both
of the factors for inflation of the capsules) an F 2 progeny consisting of 71 B.
bursa-pastoris and 17 B. Heegeri. One of these F 2 plants produced in the F 3
16 plants having triangular capsules and 3 with turbinate capsules, thus show-
ing that without doubt the B. bursa-pastoris used in this cross had monomeric
capsules. There remains one important question which the author fails to
mention. As B. Heegeri has been widely distributed in botanical gardens, it
1m
Dahlgren were a derivative of an earlier, natural
between B. bursa-pastoris and B. Heegeri, its possession of but one of the capsule
18 Gwyxne-Vaughan, D. T., On a " mixed pith " in an anomalous stem of Osmund*
regalis. Ann. Botany 28:351-354. pi. 21. 1914.
I0 Shull, G. H., Bursa bursa-pastoris and Bursa Heegeri: biotypes and hybrids.
Carnegie Inst. Washington Publ. no. 112. pp. 57. Washington. 1909.
, Defective inheritance-ratios in Bursa hybrids. Verhandl. Naturf. Ver.
Briinn49: 157-168. 1911.
, Duplicate genes for capsule-form in Bursa bursa-pastoris. Zeitschr
Ind. Abstam. u. Vererbungs. 12: 97-149. 1914.
20 Dahlgren, K. V. Ossian. Ein Kreuzungsversuch mit Capsella Heegeri Solms
Svensk Botanisk Tidskrift 9:397-400. 1915.
1917] . CURRENT LITERATURE 247
factors would give no indication of the condition of any of the original Swedish
biotypes, because plants having monomeric capsules occur normally just as
frequently as those having dimeric capsules in the offspring of the Fi and later
generations from such a cross. — Geo. H. Shull.
Liassic flora of Mexico. — Wieland's 21 superb quarto memoir of 165 pages
and 50 plates has run the gauntlet of both the Mexican civil war and the world
war, since the Spanish text has been printed in Mexico and the illustrations
are from the famous lithographic firm of Werner and Winter of Frankfort.
The only internal evidence of this situation is the rather large number of
typographical errors in the Spanish text. The material was collected in the
province of Oaxaca in the southwestern Pacific region of Mexico. For the
most part it consists of impressions of leaves, and in a few instances fructifi-
cations of cycads or supposed Cycadophyta. Remains of Cordaitales are
described also from the formation w r hich is lowest Jurassic (Lias). One could
wish, however, that the evidence in the case of this group were somewhat
more definite, for it does not seem to establish definitely the presence of the
Cordaitales in the middle Mesozoic any more than the results of Lignier have
finally established the concurrent existence of Cordaitales and palms in the
Lias of France. Only structural evidence of an unquestionable character could
do this. One Arancarioxylon is described, but it differs from that genus in its
typical form by the possession of rays of more than a single layer of cells in
width. The memoir under review stands as one of the most important recent
documents of systematic paleobotany in regard to the Cycadophyta, and takes
its place with those of the same author on the extinct cycads of the United
States and those of Nathorst on the Cycadophyta of Yorkshire, England.
E. C. Jeffrey.
Anatomy of Betulaceae.— Hoar 22 has investigated the anatomy of the
Betulaceae with reference to the phylogenetic position of the family. In the
Engler scheme, the family is placed among the most primitive Archichlamy-
deae, on the basis of flower structure. Since the most primitive family in the
Engler scheme is the Casuarinaceae, the genus Casuarina was included in the
investigation. The anatomy of the latter genus is either entirely primitive
or so generalized as to include both primitive and advanced characters, so that
its position near "the base of the dicotyledonous line" seems justified. The
Betulaceae possess the aggregate condition of rays indicative of a primitive
type, Alnus probably illustrating most completely the primitive condition of
the family. The more advanced genera (Carpinas, Ostrya, and Betula) have
21 Wielaxd, G. R., La Flora Liasica de la Mixteca Alta. BoL Inst. Geol. Mexico,
no. 31. 1916.
22
Hoar, Carl S., The anatomy and phylogenetic position of the Betulaceae.
-- 9 - / -- ^ * *
Amer. Jour. Bot. 3:415-435. pis. 16-19. 1916.
248 BOTANICAL GAZETTE [march
retained the aggregate condition only in conservative organs and regions, or
it is recalled in them by injuries. The general conclusion, therefore, on the
basis of anatomy, is that Betulaceae are rightly "ranked in a low phylogenetic
position." — J. M. C.
Hawaiian bogs. — Situated at or near the summits of high volcanic moun-
tains, at altitudes of 1000-2000 m., with a precipitation reaching the enormous
proportions of 20 m. annually, the summit bogs of Hawaii are among the most
inaccessible and remarkable in the world. In a general description of these
areas MacCaughey 23 calls attention to the similarity of these bogs to those of
other lands in general aspect and in the presence of similar mosses, sedges, and
grasses. There is an absence of many familiar forms, however, such as pitcher
plants, and many of the bog ericads and orchids; while other familiar genera
take new and strange forms, as instanced by woody violets and lobelias. Many
endemic forms occur, particularly among the dwarf trees that form clumps
scattered over the tussocky surface. — Geo. D. Fuller.
Four-lobed mother cells. — Lobed spore mother cells are very conspicuous
in Jungermanniales, and by most botanists are thought to be restricted to that
order. The work of Allen 24 adds the Musci to the list. He finds that the
spore mother cells of Catharinea show a distinct lobing, somewhat less than in
representative Jungermanniales, but nevertheless very pronounced. Lobed
mother cells are present in all of the 3 orders of the Hepaticae. Cavers
reports them in Targionia, one of the Marchantiales; they are almost univer-
sally present in the Jungermanniales ; and the reviewer finds marked lobing in
the spore mother cells of species of Anthoceros collected by him on volcanic
islets in the South Seas. The lobing of spore r
probably of phylogenetic significance, but until
been done it is idle to theorize. — W. J. G. Land
bryophyt
Roesleria and Pilacre. — As a result of a comparison of the various forms
of Roesleria pallida and Pilacre Petersii, Bayliss-Elliott and Grove 25 con-
clude, from the great similarity in structure and habit of these two fungi, that
both are forms of the same plant, and that Pilacre Petersii, long regarded
as a primitive basidiomycete of the auriculariaceous type, is therefore nothing
more than the conidial form of the ascomycete Roesleria pallida.
H. Hasselbring.
* MacCaughey, Vaughan, Vegetation of the Hawaiian summit bogs. Amer.
Botanist 22:45-52. 1916.
** Allen, Charles E., Four-lobed mother cells in Catharinea. Amer. Jour. Bot.
3:456-460.7^.2. 19 16.
2 5 Bayliss-Elliott, Jessie S., and Grove. W. B., Roesleria pallida Sacc. Ann.
Botany 30:407-414. figs. 11. 19 16.
1
VOLUME LXIII
NUMBER 4
THE
Botanical Gazette
APRIL 1917
ENVIRONMENTAL INFLUENCES ON NECTAR
SECRETION
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 228
Leslie A. Ken oyer
This study was undertaken to summarize and supplement exist-
I ing knowledge of the factors which stimulate or retard the secretion
1 of nectar. The work was carried out under the direction of the
botanical section of the Iowa State Experiment Station in coopera-
tion with the chemical section, being done mostly at Ames, Iowa,
A
from June 1914 to June 1916.
Historical
with
nvironmental
tion, was written by Bonnier (i). The subject of secretion has
been much debated from a physical standpoint. Godlewski (9)
attributes it to a fluctuation in the concentration of the cell sap
due to alternate splitting and recombination of complex molecules.
Pfeffer (19) advances 3 possible causes for secretion: (1) an
unequal permeability of the membrane of the absorbing and
excreting portions of the cell; (2) an unequal distribution of solutes
in the absorbing and excreting portions of the cell; (3) the trans-
formation into sugar of the outer portion of the cell wall, and the
osmotic action of this sugar upon the liquid contents of the cell.
Lepeschkin (14), in a study of the coenocytic plant Pilobolus, finds
249
250 BOTAXICAL GAZETTE [april
evidence that the first of Pfeffer's theories is the correct one for
the excretion of water drops. Wilson- (29) gives evidence in sup-
port of Pfeffer's third theory, showing that the thorough washing
of a nectary stops the secretion if the nectary is past the stage of
metamorphosis of the cell wall, but that secretion is resumed on
the addition of sugar to the surface of the nectary. The validity of
his results is called in question by Lepeschkin (14) and Busgen (5).
Haupt (10) in a study of extrafloral nectaries finds that some
nectaries become inactive after washing, while others, as those of
the leaves of Impatiens parviflora, continue excretion of water but
not sugar, thus becoming equivalent to hydathodes. Livingston
(16) likens nectar secretion to guttation, accounting for the latter
by a decrease in the permeability of the plasma membrane induced
by an increased turgidity, and for the former by a hypothetical
rapid increase in the solute content and thereby of the osmotic
pressure in the cell, a change which induces a like decrease in the
permeability of the membrane.
Comparatively little work has been done on the chemistry of
nectar. Wilson (28), Von Planta (27), and Bonnier (i) have
analyzed a few kinds of nectar, finding that in some cases it con-
tains no sucrose, while in others it is almost wholly this kind of
sugar. In some cases fructose and in others glucose is the domi-
nating reducing sugar. The sucrose of nectar is almost wholly
digested in honey, Browne (4) finding as the average composition
of 138 honey samples from widely separated localities 38.65 per
cent fructose, 34.48 per cent glucose, and 1. 76 per cent sucrose.
Investigation
METHODS
m
means of a graduated capillary pipette, or weighed after absorption
on strips of filter paper which had previously been weighed in small
vials. Many of the most important honey plants secrete such
small amounts of nectar to the individual flower that neither of
methods
determined
amount of sug
I I
I
191 7] KENOYER— NECTAR SECRETION 251
volume of water to a counted or weighed quantity of the flowers,
shaking frequently for half an hour, then decanting. A similar
method was employed by Von Planta (27) and Bonnier (2). In
some of the flowers investigated, this treatment extracts some
sugar from the floral tissues, as shown by the appearance in the
solution of colors from the floral envelopes, hence it is of value
mainly for the comparison of flowers of the same species. Buck-
wheat, because of its rapid maturing, its value as a honey-producing
source
was employed in many of the experiments.
Sugar determinations were made by reduction of Fehling's solu-
tion. The method found most practicable and employed for the
greater part of the work was based on that described by Schoorl
(24). A carefully measured amount (1 cc. for minute quantities of
sugar, 10 cc. of the material to be analyzed in a 1500c- Erlenmeyer
flask) was heated on an asbestos gauze over a flame so adjusted that
the liquid began to boil in just 2 minutes, and then was boiled for
2 minutes longer. To the contents of the flask after cooling to
6o° C. were added sulphuric acid and potassium iodide. The liber-
ated iodine, which corresponds to the unused copper sulphate, was
titrated against sodium thiosulphate. Sugar values were obtained
by the careful analysis of known quantities of sugar. This method
has the advantage of being both rapid and delicate enough to deter-
mine minute quantities of sugar with a probable error of not over
o.o4mg. Floral tissues, when not too bulky, could be analyzed
by the same method, the reagents being added directly to the
tissues after covering them with water. When tissues were more
bulky or when greater accuracy was required, extractions were
made with alcohol or water, and were purified by treatment with
neutral lead acetate.
HUMIDITY
It is a well known fact that any watery exudation from plants
accumulates when atmospheric humidity is high and evaporation
is thereby retarded. This can easily be demonstrated in connection
with bleeding from severed tissues or with guttation through water
stomata. Bonnier (i) states that nectar secretion corresponds
to guttation and that it varies inversely with the transpiration.
2 5 2
BOTAXICAL GAZETTE
[APRIL
So far as the volume of nectar is concerned, I have found this
to be true in all the plants experimented upon with this end in
view. But there are two factors involved in nectar secretion, as
shown by Pfeffer (20), the exudation of water and that of sugar.
Haupt (10) has found that extrafloral nectaries begin secreting only
when humidity is relatively high, an observation which confirms
the theory that secretion is due to a decreased permeability caused
by increased turgor, but that after secretion begins increased air
moisture increases water secretion, the secretion of sugar remaining
constant. It is probable that this applies to nectaries in general.
more
times
Ames
humidity, the summer months of the former year being
dry and warm, while those of the latter year were exce
and cool. Hence comparisons of nectar washed from
given in table I, are of interest.
'
TABLE I
Species
1914
Melilotus alba, flowers
Medicago sativa, flowers
Trifolium pratense, corollas.
Number of
samples
analyzed
6
4
4
Average mg.
sugar per gm.
1915
Number of
samples
analyzed
Average mg.
sugar per gm
2I 3
3-64
3
3
13
0.65
0.80
3 90
It is seen that the wet season yields rather less sugar than the
dry.
may be stated further that bee visitors
several times as abundant in 1 914 as in 191 5. I have found by
experiment that flowers of alfalfa grown in dry soil contain about
60 per cent more sugar than those grown in wet soil.
Buckwheat flowers kept humid under a bell jar secreted much
more liquid than flowers exposed to the rather dry greenhouse air.
However, 12 comparative analyses of the nectar of each show
1.04 mg. sugar per 100 blossoms in the humid, and o. 08 me. sugar
per 10 blossoms in the dry.
remov
74 mg.
t
1917] KENOYER— NECTAR SECRETION 253
10 blossoms in the humid and o. 98 mg. per 10 blossoms in the dry.
More sugar accumulates in a dry atmosphere and practically the
same amount is excreted.
The accumulation of sugar under low moisture conditions is in
line with the discovery by Lundegardh (17) that increase of mois-
ture favors the accumulation of starch; decrease of moisture favors
its digestion.
Six plants of Impatiens sultana in saturated air accumulate in
a day 3 . 26 mg. sugar each from the extrafloral nectaries (the basal
teeth of the leaves), while 6 plants in greenhouse air accumulate
5.42 mg. sugar each. The excess of the latter is very likely due
in part to the running away of drops under the humid conditions.
The nectar averages 23.4 per cent sugar in the former and 45.3
per cent in the latter.
RAINFALL
The author has shown in a statistical study (12) that heavy
rainfall just before the secreting season is advantageous, as it gives
the plants greater vigor. But during the season of greatest secre-
tion good years are somewhat drier than poor. Also a rainy day
shows a lighter honey yield than a day before or after the rain.
The deterrent effect of the rain on the honey flow is twofold: it
hinders the activities of bees and it washes away the nectar. To
illustrate the latter point, in 191 5 on the morning following a day
of continual rainfall, red clover corollas w r ere found to contain
0.02 mg. sugar per gm
contained
3 . 8 mg., a day later o. 6 mg., and 2 days later 4.4 mg. Buckwheat
blossoms w r ere subjected to an experiment to determine the extent
to which rains wash away the nectar. Flowers subjected before
gathering to a spray for 20 minutes, 15 mm. of water falling, were
found to contain o.i2mg. per 10 as against 1 . 28 mg. per 10 of
untreated flowers. A 30-minute rain of 35 mm. reduced the nectar
of red clover blossoms from 0.48 to o. 19 mg. per 10, and that of
wniic clover blossoms from o. 27 to 0.07 mg. per 10.
TEMPERATURE
Wilson (29) states that temperature has not a marked effect
upon the rate of secretion of nectaries that have commenced
254
BOTANICAL GAZETTE
[APRIL
secreting. He finds, however, that Prunus laurocerasiis will not
begin secretion unless the temperature is 12 C. or over. Haupt
(10) also finds that a minimum temperature is necessary to induce
secretion. Lepeschkin (14) finds in the hyphae of Pilobolus a
secretion steadily increasing with, and much more rapidly than, the
absolute temperature. In other cases he finds an optimum above
which secretion diminishes. In the case of secreting hairs of the
bean leaf this optimum is 20 , in the Abutilon nectary it is 26 .
Experiments were carried out in uniform temperature incuba-
tors. For much of the work, to avoid light exclusion, which is
detrimental to secretion, incubators were employed which w r ere
specially constructed for the purpose, being covered with two glass
plates separated by an air space.
The optimum temperature for amount of secretion lies between
20 and 25 for Cucurbita Pepo, Lilium speciosiim. Carina indica,
Euphorbia pidcherrima, and extrafloral nectaries of Impatiens
Sultani. For Salvia splendens and most of the Leguminosae tested
. As a rule, the sugar concentration of the nectar
1
:>
it is about
does not differ materially for the different temperatures. Typical
sugar determinations obtained from the flower of Abutilon striatum
are given in table II, the blossoms being quartered and one piece of
each placed in each incubator, thereby eliminating any error due
to individual variations.
TABLE II
Time
Mg» invert sugar per flower
io'
After 36 hours
After 16 hours (another set)
10.20
3°7
16
23
3°'
12.00
6.57
16.00
12.97
10.32
10.87
v
1
Here the optimum is clearly not far from
AH
nectar secretion is greater in the same species at high latitudes and
altitudes than at low
grows norn
compared, and furthermore
Alps. He
Norway
-*-
1917] KEXOYER— NECTAR SECRETION 255
between maximum and minimum daily temperatures which pre-
vails at high altitudes and latitudes, or to the greater range in the
humidity of the air.
Phillips (21) observes that alfalfa in general is valuable as a
honey plant in the Great Plains region of the west and not in the
eastern states; that buckwheat is of more value in New York,
Pennsylvania, and Michigan, than in Indiana and Illinois; and that
white clover is of greater importance in the north than in the south.
Basswood is said to secrete better in the more northerly portions
of its range. It seemed desirable, therefore, to investigate the
hypothesis of Bonnier.
As I have show r n (12), the study of a 30-year weight record of
a hive at Clarinda, Iowa, lends strong support to this assumption.
Thirty-eight periods of continual and fairly rapid gain in weight
were selected, and the days of each divided about equally betw r een
days of high gain and days of low gain. In 32 cases the average
diurnal temperature range for the days of high gain was greater
than that for the days of low gain. In all of the 6 exceptional
cases the difference between the average was small. Sladen (25)
states that the heaviest single day's increase in hive weight noted
for two seasons in England in a record kept by Ede w r as on a day
that began with a heavy early morning frost, the honey coming
from the heather (Calluna vulgaris).
Table III represents the amount of reducing sugar in mg. which
the author found after keeping the plants or flowering branches for
a time in the incubators.
In field conditions it can readily be shown that lower tempera-
tures increase the sugar content in dandelion and the clovers.
How does high temperature influence secretion ? Van Ryssel-
berghe (26) determined that with increase in temperature the
permeability of the protoplast to water and solutes rapidly increases,
that of Tradescantia epidermal cells for water being 8 times as great
at 30 as at o°, and that for solutes seeming to follow the same pro-
• portional rule. To demonstrate whether this holds for nectary
cells, I determined the lowest sucrose concentration necessary to
plasmolyze the multicellular secreting hairs which cover the nectary
of Abutilon. After 4 days at io° a 0.6 molecular solution is
>
256
BOTANICAL GAZETTE
[APRIL
sufficient; while for another portion of the same flower, after
4 days at 25 a
1. 1
molecular solution is necessary.
TABLE III
Species
io'
Trifolium incarnatum, 10 corollas,
2 days
Trifolium repens, 10 flowers, 2 days
Nectar washed from same
Trifolium repens, 10 flowers, 2 days.
Nectar washed from same
Medicago sativa, 10 flowers, 4 days
Caragana frutescens, 10 flowers,
2 days
Nectar washed from same
Fagopyrum esculentum, 10 flowers,
4 days
Nectar washed from same
Salvia splendens, 10 corollas, 4 days
Coleus Blumei, 10 corollas, 4 days. .
Taraxacum officinale, per gm. flowers,
1 day
Taraxacum officinale, per gm. flowers,
1 day
0.56
°-93
0.0
3 44
3755
0.64
0.69
1.36
38.7
15 6
19'
O.63
I. 12
O.O7
O.63
O.O
2.08
22. 22
4.80
0.73
O.80
25.7
O.86
45 °
17. I
25
0.43
O.94
0.02
0.47
O.O
O.52
n-95
2.00
o. S 8
0.0
138
0.78
19-3
11. 9
30
0.38
0.70
O.OI
12.9
0.62
139
not
develop
ing
10°
( 23 over
night)
O.56
0.08
2433
2.88
What is the influence of low temperature ? Mt)
accumulat
temperature is below id
and various other plant organs. He
same
comes from the digestion of starch or oil more
destruction
temperat
from
ture in the twigs of woody plants is a well know r n phenomenon
which is amply discussed by Fischer (8) . Indeed this accumula-
tion seems to be rather common in its occurrence among plant
tissues. Besides being applicable to floral tissues, as table III
clearly shows, it affects the leaves and the peduncles of white clover,
the former after 2 days' treatment having 30 per cent more sugar
than at 25 . The evidence
more
uniform
1917]
KEN OYER— NECTAR SECRETION
257
1
of nectar is a balance between two factors, namely, the accumula-
tion of sugar in and near the flower under the influence of low
temperature, and increasing permeability of the plasma membrane
under the influence of high temperature. The position of the
optimum, then, might be represented somewhat as follows:
Graph of sugar accumulation
Graph of permeability of
protoplast to sugar
Optimum secretion temperature
Temperature o
10
20
30
The two graphs are limiting factors to nectar secretion, and the
intersection, that is, the point where the effective limit stands
highest, is the optimum secretion temperature. If the fact dis-
covered by Eckerson (7) for root cells, that above a certain point
(25-35°) the permeability again decreases, applies also to nectary
cells, the situation may be somewhat complicated thereby.
Better than any uniform temperature for secretion is a change
from a lower to a higher temperature, as table III indicates. The
influence of such a change might be graphically indicated by folding
the above diagram so that two temperatures, say io° and 30° are
brought together. Both limiting factors are raised; the sugar
which has accumulated at the lower temperature is secreted at the
higher.
ATMOSPHERIC PRESSURES
In the study previously cited (12), I have shown that of 18
periods of continual honey production, 16 have a lower barometric
pressure on the days of heavier yield than on the days of lighter
yield, the two exceptional cases having very slight differences. The
increased secretion already credited to high altitudes might be
258 BOTANICAL GAZETTE [april
attributed to the diminished pressure, but this explanation would
not account of course for the similar increase at high latitudes.
In investigating experimentally the influence of pressure, I
covered the plant under experiment with a tabulated bell jar waxed
to fit tightly to a ground glass plate and connected by means of a
stopcock with the water aspirator. A similar plant was placed *
under a control bell jar. In some of the experiments air was daily
renewed in both low pressure and control jar; in others its con-
tinual renewal was provided for by admitting a current of air which
bubbled through water, and in the case of the low pressure jar
entered by means of a capillary tube with a very small aperture.
This latter method is similar to one employed by Schaible (22).
By the use of an aneroid barometer the pressure was maintained at
about 50 cm., or two-thirds atmospheric pressure, the prevailing
condition at altitudes of about 10,000 ft. Repeated investigations
were made with the following plants: for guttation, Tropaeolum
majus and Avena saliva; for nectar secretion, Tropaeolum majus,
Impatiens Sultani, A but Hon striatum, Euphorbia pulcherrima, Canna
indica y Fagopyntm esculentum, Salvia splendens, Coleus Blumei,
Antirrhinum majus, and Prunus americana.
There were no constant differences in secretion which could be
detected by either physical or chemical means. It is very doubtful,
mea
which
It is a
more
warmth
periods favoring activity. Hence it seems very probable that any
relation between atmospheric pressure and honey flow is to be
attributed to the bees and not to the plants.
LIGHT
Haupt
the extrafloral nectaries of several species of Vicia are stimulated
to activity by light. The first author adds Lobelia erinus and the
last the Euphorbiaceae as plants that require the light stimulus
■
for secretion. The two latter authors, however, state that in the
greater majority of cases secretion is only indirectly related to
IQI7]
KENOYER— NECTAR SECRETION
259
light. Haupt finds that in most extrafloral nectaries even dis-
turbances in photosynthesis by darkness show their influence on
secretion only very slowly. Light in Vicia doubtless increases the
permeability of the protoplast, as Lepeschkin (15) has found that
it does in the pulvini of Leguminosae in general.
Schimper (23) found that extrafloral nectaries on the leaves of
Cassia neglecta cease their activity in a few days when the plant is
kept in darkness or in an atmosphere deprived of carbon dioxide,
but that secretion continues when the leaf is in the light and only
the nectaries are darkened.
I experimented upon both the floral and the extrafloral nectaries
of Impatiens Sultani, and it seems clear that the withdrawal of
light makes its influence fairly rapidly and very decidedly felt.
Table IV gives a typical study of floral nectaries, the measurements
being millimeters in length of the part of the spur which contains
nectar. The table includes average increases over last measure-
ment of the spur in those flowers which were open when the last
record w r as taken, and the average measurement for those flowers
which have opened since the last record. One plant was covered
by a bell jar, the other was covered by an opaque jar of about the
same size.
TABLE IV
Days
Light
Dark
Gains
2
3
4
6
7
8
9
10
4
4
2
3
5
4
3
3
4
8
o
1
3
2
New flowers
Gains
New flowers
21.6
22.0
23.0
29.0
20.0
21.7
19.0
22.0
time
1.2
16. 1
I . t
13.6
I I
15-7
— 1.2
17 -3
O. I
16.0
o-5
14.0
-0.4
130
-0.5
0.0
n on an
etiolated appear
/elooins:.
Secretion fron
ance and new flowers were scarcely developing.
extrafloral nectaries had practically stopped after 3 days in the dark.
Half the leaves of a plant were covered with black tissue paper
means
260 BOTAMCAL GAZETTE [april
basal or nectar-secreting teeth being left uncovered. These leaves
secreted very little after the third day, whereas the uncovered
leaves of the same plant were uninterrupted in their secretion.
Buckwheat flowers were gathered at the same time from under
light and dark jars, and it was found that after two days in the dark,
although the total amount of liquid secretion was not in the least
diminished, the proportion of sugar began to decrease, the secre-
tion not tasting sweet or giving a very positive sugar test. An
average of 1 1 such analyses of the nectar of flowers that had been
covered for 2-8 days gives per 10 blossoms 1 . 20 mg. invert sugar
in the light, and 0.41 mg. in the dark. Sugar contained in the
flowers does not differ greatly, however, in the two cases, there
being o.79mg. to 10 flowers from the light and o.73mg. to 10
flowers from the dark. Plants which had been left in the dark for
time continued to secrete less than normal quantities of
some
more after the removal
diminution
a number of plants.
;h
mi
from
remov
from
checks. Seven of the above pairs of cases give for the entire
mg
and 0.92 mg. from the check.
The same result may be gained by covering all the leaves of the
plant with black tissue paper, and comparing the nectar with that
of normal plants. Here we find as an average of 6 analyses of 10
flowers o. 2$ and o. 69 mg. invert sugar respectively in the nectar;
0.83 and 1.40 in the whole flowers. After 4 days in the dark
there is approximately one-fourth as much sugar secreted per
flower.
When the flowers only are covered from the light, they secrete
fully as much sugar as those not covered ; so the extrusion of sugar
is clearly dependent upon the food reserves of the plant.
relation to exist in the Canna blossom. Dark-
same
materially diminished
while darkening the flower cluster alone had no influence upon it
1917] KENOYER— NECTAR SECRETION 201
Other flowers analyzed , among them being Antirrhinum majus,
Cucumis sativus, Salvia splendens, and Coleus Blumei, contain less
sugar and secrete less sugar when kept in the dark; furthermore,
the nectar is usually less in volume. Euphorbia pule her rima does
not begin secretion in a dark chamber, and Abutilon striatum
secretes only very slowly and very scantily. Even plum branches,
which contain supplies of stored food, when developed in the dark
have little more than half as much sugar in the tissues and about
one-fourth as much nectar as when developed in the light.
FERTILITY OF SOIL AND VIGOR OF PLANT
Hunter (ii) states that alfalfa yields the greatest amount of
nectar under conditions that tend to give it the most vigorous
growth, proper heat, and moisture upon suitable soil. All of my
observations and experiments tend to confirm this for the various
plants investigated. Red clovers grown on fertilized plots were
found to contain slightly more sugar and to secrete slightly more as
nectar than those on the unfertilized control plots adjoining.
Bonnier (2) has experimented on the secretion of several plants
as influenced by different soils. He finds that Sinapis alba, Isatis
tinctoria, and Medic ago sativa yield most nectar on limy soil, while
Phacelia tanacetifolia does better on clay and Fagopyrum esculentum
on sand. It is probable that soils which are conducive to greater
vigor and more surplus food in the plant are on the whole more
favorable for nectar yield.
White clover, the leading honey plant of this section, collected
the same day in the same part of the city gives the tests shown in
table V.
TABLE V
Condition
Sugar per gm. of flowers is
Nectar Flowers
Stunted by rank growth of weeds. . .
Stunted by close mowing
Vigorous
Vigorous plants of buckwheat yield about twice as much nectar
as do weak ones in the same bed. The flowers are found on analysis
262
BOTANICAL GAZETTE
[APRIL
to contain 20-50 per cent more sugar. Plants which had been
allowed to dry to the wilting point several times in the course of
their growth and were consequently stunted to about one-half
normal height yielded less nectar, the average of 6 comparisons
being o.44mg. per 10 flowers of the stunted and 1.39 mg. per
10 flowers of the normal. Plants grown in a greenhouse in which
the temperature was low and which consequently were stunted to
about one-third normal height, not blooming until twice the age
of normal blooming plants, secreted practically no nectar.
It was noticed further that a Salvia deeply rooted in the soil
secreted more than one which was hampered by a small pot, and
that of the former plant young vigorous branches yielded more
nectar than old stunted ones.
PORTION OF FLOWERING PERIOD AND AGE OF FLOWER
Table VI illustrates the relation of nectar secretion to the part
of the flowering season in which the flower in question appears.
In all cases the compared flowers were collected on the same day,
but from patches varying in stage development.
TABLE VI
Species
Trifolium pratense
Medicago sativa per gm. of
flowers
Buckwheat 10 flowers (aver-
age of 4 tests)
Early in blooming season
Sugar ia nectar
Sugar in flowers
Late in blooming season
Sugar in nectar Sugar in flowers
93
1-5
1.62
20.7
38.9
0.72
4.6
0-3
I.09
18.6
26.8
O.60
more
synthesis and has greater reserves of food to be secreted by the
nectaries.
com-
mences very rarely before the dehiscence of the anthers; it is
most
and it ceases
as soon as the fruit begins to develop. Bonnier (i) agrees to this
proposition and asserts that nectar is simply a manifestation of the
surplus of food stored in the nectariferous part corresponding to an
1917]
KENOYER— NECTAR SECRETION
2O3
arrest in the development of the organ. In the case of floral nec-
taries, therefore, it is most pronounced after the ovary has attained
maximum development and before the fruit has commenced to
develop. He finds a maximum proportion of sucrose in the floral
time
Chemical
analyses of the floral tissues show that the climax of sugar accumu-
lation is about the time of the dehiscence of the stamens, and that
as the flower withers there is a very rapid decrease in the amount
of sugar. Table VII gives some examples from my work, the
tissues having been extracted and purified.
TABLE VII
Species
Buds
Invert
sugar
Sucrose
Medicago sativa per gm . . .
Melilotus alba per gm
Melilotus officinalis per gm.
Trifolium repens per gm . . .
Trifolium hybridum per gm.
Taraxacum officinale
gm
per
Impatiens Sultani per 100
flowers
Lilium speciosum rubrum
per flower
Lilium longiflorumf younger
per flower \older . . .
32
22
16
8
13
5
2
o
1
8*
■
Mature flowers
Invert
sugar
17.8
2.8
2.6
O.O
O. I
47-5
"9-5
51.4
95 9
0.0
26.7
14.9
21.3
654
3ii
28.8
8.3
8.6*
Sucrose
Declining flowers
Invert
sugar
27.2
248.4
179 3
95-2
0.0
Trace
0.0
1.8
0.0
10.9
ii-3
26. 1
7-5
190.0
76.0
22. 2
Sucrose
O.O
OO
48.9
I.O
O.O
* Including sucrose.
most
form oj
begins.
mmary
1. By increasing humidity the secretion from nectaries of water
but not that of sugar is increased.
o — — —
. Excessive water supply lessens the sugar surplus in the parts
of the flower.
3. Dilution and washing by rain cause much of the sugar of
nectar to be lost.
4- Rate of secretion for both sugar and water increases with
temperature up to a certain optimum.
264 BOTANICAL GAZETTE [april
5. Accumulation of sugar in the flower and its vicinity varies
inversely as the temperature.
6. The optimum condition for sugar secretion is an alternation
of low and high temperatures.
7. Variation of atmospheric pressure has no marked influence
on secretion.
8. Sugar excretion is markedly diminished in darkness on
account of limitation of the food reserves of the plant. Water
excretion may or may not continue, depending upon the species.
Removal of the leaves has the same deterrent effect.
9. The more favorable all conditions for growth and the more
greater is the amount
blooming
. Nectar is most abundant early in the
things being equal.
. Accumulation and secretion of sugar is most
he time of the opening of the flower.
Grateful recognition is due Drs. Pammel, Dox, and Coover, of
Iowa State College, Drs. Cowles and Crocker of the University
of Chicago, Dr. Phillips of the Bureau of Entomology, and
Mr. Pellett, Bee Inspector for Iowa, for encouragement and
assistance in this work.
Ewixg Christian College
Allahabad, India
LITERATURE CITED
1. Bonnier, G., Les Nectaries. Ann. Sci. Nat. Bot. 8:1-212. 1879.
2. — -, Influence du terrain sur la production du nectar des plantes.
Ass. Fr. Av. Sci. 2:567, 569. 1893.
3. Bonnier, G., and Flahault, Ch., Observations sur les modifications des
vegetaux suivant les ponditions physiques du milieu. Ann. Sci. Nat. Bot.
7:108-113. 1878.
4. Browne, C. A., Chemical analysis and composition of American honeys.
U.S. Dept. Agric. Bur. Chem. Bull. no. no.
5. Busgen, M., Der Honigthau. Jenaische Zeitsch. Nat. 25:339-428. 1891.
6. Darwin, C, Cross and self-fertilization in the vegetable kingdom. 1877
(chapter x).
7. Eckerson.
Bot. Gaz. 58:254-263. 1914
8. Fischer, A., Beitrage zur Physiologie der Holzgewachse. Jahrb
Bot. 22:73-160. 1886.
r*
!
191 7] KENOYER— NECTAR SECRETION 265
9. Godlewski, E., Zur Theorie der Wasserbewegung in den Pflanzen. Jahrb.
Wiss. Bot. 15:602. 1884.
10. Haupt, H., Zur Secret ionsmechanik der extrafloralen Nektarien. Flora
1
90:1. 1902.
11. Hunter, S. J., Alfalfa, grasshoppers, bees. Bull. Dept. Ent. Univ.
Kansas. 1899.
12. Kexoyer, L. A., The weather and honey production. Iowa State Exper.
Sta. Bull. 1916.
13* Kurr, O. G., Bedeutung der Nektarien in den Blumen. Stuttgart. 1883.
14. Lepeschkin, W. W., Zur Kenntniss des Mechanismus der aktiven Wasser-
ausscheidung der Pflanzen. Beih. Bot. Centralbl. 19:409. 1906.
15- , Kenntniss des Mechanismus der Variationsbewegungen, und der
Einwirkung des Bedeuchtungswechsels auf die Plasmamembran. Beih.
Bot. Centralbl. 24:308-356. 1911.
16. Livingston, B. E., The role of diffusion and osmotic pressure in plants.
1903.
17- Lundegardh, H., Einige Bedingungen der Bildung und Auflosung der
Starke. Jahrb. Wiss. Bot. 53:421. 1903.
18. Muller-Thurgau, H., Uber Zuckeranhaufung in Pflanzentheilen in
Folge niederer Temperatur. Land w. Jahrb. 11:751. 1882.
19- Pfeffer, W., Osmotische Untersuchungen. 1877.
20. , Studien zur Energetik der Pflanze. 1892 (p. 267).
11. Phillips, E. F., Beekeeping. 191 5 (pp. 207 and 362).
22. Schaible, F., Physiologische Experimente uber das vermindertem Lttft-
druck. Beitr. Wiss. Bot. Funfstiick 4:93-148. 1900.
23- Schimper, A. F. W., Pflanzen und Ameisen. 1888.
24. Schoorl, N., Zur jodometrischen Zuckerbestimmung mittels Fehling'scher
Losung. Zeit. Angew. Chem. 27:633-635. 1899.
25. Sladen, F. L., Secretion of nectar. Beekeeper's Review 27:419. 1914.
26. Van Rysselberghe, F., Influence de la temperatur sur la permeabilite du
protoplasme vivant pour Teau et les substances dussoutes. Rec. Inst.
Bot. Bruxelles 5:209-249. 1901.
27. Von Planta, A., tJber die Zusammensetzung einiges Nektar-Arten.
Zeitsch. Physiol. Chem. 10:227-247. 1886.
28. Wilson, A. S., Chem. News 38:93. 1878.
29. Wilson, W. P., The cause of the excretion of water on the surface of
nectaries. Unters. Bot. Inst. Tubingen 1:1-22. 1881.
\
DEVELOPMENT OF EMBRYO SAC AND EMBRYO IN
EUPHORBIA PRESLII AND E. SPLENDENS
Wanda Weniger
(with PLATES xiv-xvi)
Introduction
yathium of Euphorb
staminate
stamen
assumpti
them the
namelv. that the cvathium
r\e pistillate flower and many staminate flowers.
The earliest monograph of the Euphorbiaceae was that of
Baillon (i), in 1858. He found that a character common
family
The
becomes
—
the outer one of which usually disintegrates. The embryo is sur-
rounded by an oily endosperm and has a rudimentary root cap.
Baillon's figures, reproduced by Strasburger (20), show the
and
name
mass
grows
determine
pollen tube. The nucellus grows out into a beak before the time of
fertilization and the cells of the obturator grow close to the nucellus.
The obturator was called by Mirbel (9) a "chapeau de tissu
" by Payer (15) a "capuchon," and by Capus (3
Myrsinites in particular, a "coussinet microp>
71
Poissox (16) describes the integuments and obturator of E.
ovule
Peplis. Pax's account (14) of the structure of the
According: to him
same
-Miss Lyox (8) gives a full account of the life history of E
lata. There are 3 carpels in each pistillate flower, forming
Botanical Gazette, vol. 63]
[266
1917] WENIGER— EUPHORBIA f 267
Sin
locule. The inner integument
while the outer integument grows beyond it. The megaspore
subepidermal in origin
ermis
embryo sac, divide with great rapidity, producing a long, slender
imbrj
The embryo
from
megaspores. The syner
the egg is
esr^.
situated between them. The pollen tube passes between the
synergids, and the fusion of the male nucleus with the egg nucleus
was observed. The fusion of the polar nuclei takes place near the
e ephemeral and were seen by Miss
Lyon but once. The neck of the nucellus and the " glandular
hairs," as the cells of the obturator are called, disintegrate after the
entrance of the pollen tube, and the outer integument closes the
mouth of the micropyle.
Hegelmaier (6) reports habitual polyembryony in E. dulcis.
From 2 to 9 embryos appear at the micropylar end of the sac. One
embryo, which comes from the egg and may be distinguished from
the others by the presence of a suspensor, develops into the single
embryo of the seed. Some of the supernumerary embryos come
from the nucellus. Two of them often reach the cotyledon stage,
with tissue systems differentiated; the other embryos appear as
irregular masses. Since the cyathium of this species has a very
small neck, Hegelmaier thinks it improbable that the flowers
are insect pollinated. Wind pollination is also improbable, because
of the regularity with which seeds are formed in the locules. In a
later paper Hegelmaier (7) admits that, although fertilization in
E. dulcis was not observed and although its possibility seems les-
sened by the sterility of a large proportion of the pollen grains, he
occur. Fertilization is not necessary
>rvn*; farm) rmrellar cells. There is a
cannot
em
possibility that apogamy and also parthenogenesis occur.
Roeper (17) reports observing 2 embryos in the seed of E. platy-
phylla. According to De Caxdolle (5), 2 embryos are also formed
in E. helioscopia. Schweiger (19) describes the obturator, nucellus,
268 BOTANICAL GAZETTE [april
ment
Euphorbia. The outer integu-
rier. The obturator of E. Myr-
sinites begins as a small outgrowth from the placenta when the
outer integument has grown almost half-way to the tip of the
nucellus. The cells of the obturator increase rapidly, the outer
ones becoming long and hairlike. At the time of fertilization, the
mature
micropyle. The long cells of this structure com
integuments
never grow into the nucellar tissue. The obturator gradually
egrates
small swellin
form
The
nucellus has a long, slender tip which is surrounded by the cells of
6
the obturator. The caruncula is formed from the outer int
after the embryo has developed. A row of cells differentiates it
from the seed proper. This structure resembles a cap and aids in
loosening the seed from the placenta at the time of dispersal.
Schmidt (i8) finds more than one megaspore mother cell in
E. palustris. These are situated deep in the cells of the nucellus.
His account of the development of the flower agrees with that of
Miss Lyox (8).
Modilewski (n) describes an unusual development of the
embryo sac in E. procera. The first 4 nuclei of the embryo sac are
arranged in the form of a cross. Two divisions result in the forma-
tion of 4 tetrads of nuclei. One nucleus from each group migrates
to the center of the sac, where the 4 unite. The mature embryo
sac contains an egg apparatus, 3 antipodal cells, and 2 groups of
3 nuclei each, lying on opposite sides of the sac. In fertilization,
one male nucleus fuses with the egg nucleus, and the other male
nucleus fuses with the quadrivalent fusion nucleus in the center.
The synergids, antipodals, and nuclear groups at the sides of the
sac disintegrate. No case of polyembryony was observed. Later,
Modilewski (12) described the events preceding embryo sac
development in E. procera. An archesporial row of 3 or 4 cells
was found, each ultimately containing 4 nuclei. Only one of the
4-nucleate cells develops into an embryo sac. Often one or more
i9i 7] W EN IGER— EUPHORBIA 269
of the other cells of the row adheres to the developing sac for some
time before it disintegrates.
According to Modilewski, the embryo
salicifolia, E. globosa, E. meloformis, E. Cyp
LathyruSy
heteroph
helioscopia, E. Gerardiana, E. Ip
Dessiatoff (4) describes the for-
mation of 16 nuclei in E. virgata, in a manner similar to that described
by Modilewski for £. procera (n). In a still later study, Modi-
lewski (13) finds 16 nuclei in the embryo sac of E. palustris.
The development proceeds exactly as in E. procera. On the other
hand, the embryo sacs of E. virgata and E. lucida develop in the
ordinary way. Modilewski, whose material for the study of
£. virgata was collected from various localities, disagrees with
Dessiatoff's notion of the structure of the embryo sac in this
species (4). He thinks that the nuclei in Dessiatoff's i
of the embryo sac resemble endosperm nuclei more than they do
those of ordinary embryo sacs. He finds, also, that at the 2- and
4-nucleate stages the megaspore enlarges so rapidly that its wall
becomes indistinct, and that the cells of the nucellus. which have
been pushed aside in the growth of the spore, might easily be
taken for nuclei of the developing gametophyte. Dessiatoff,
according to Modilewski, mistook either endosperm or nucellar
nuclei for nuclei of the mature embryo sac. If this is not the
explanation of his results, Modilewski thinks Dessiatoff was
mistaken in the determination of the species studied. Mo BIOS do)
has recently figured the relation of the integuments and obturator
to the nucellus in E. macrorrhiza.
E. procera and E. palustris, on the present evidence, seem to be
the only species of Euphorbia studied which deviate from the usual
history of the embryo sac. In these species, Modilewski found
that since the endosperm nuclei are very large and usually contain
2 or 3 nucleoles, there is no danger of their being confused with the
nuclei of the mature embryo sac.
Material and methods
Flowers and seeds of Euphorbia Preslii were collected in differ-
ent stages of development during July and August 191 5, along
270 BOTANICAL GAZETTE [april
railroad tracks in Madison, Wisconsin. They were fixed in
Flemming's strong, medium, and weak fixatives, the first named
giving the best results. Young buds, flowers, and seeds of £. splen-
dens were fixed in various fixing solutions, including Flemming's,
Carnoy's, and JuePs, and acetic alcohol fixatives. The best results
in this case were obtained with the latter, the Flemming solutions
failing to penetrate soon enough, due to the great amount of
latex in all portions of the plants. The material was obtained
during March and April 1916, from plants grown in the greenhouse.
Sections were cut 5 or 6 /x in thickness. Some sections of embryos
10 n thick were made. Flemming's triple stain was used with good
results.
Observations
Euphorbia Preslii
t
Cyathium
The first evidence of the formation of the cyathium in this
species is the appearance of a papilla (fig. 1, p) between 2 bracts
(b) at the end of a peduncle. At the base of this papilla, staminate
in\>
grow
cyathium
small
(p). The carpels (c) of the pistillate flower appear
:he papilla and gradually grow up about it, forming
stigmas (fig. 4, sg) . The inv
staminate
The
staminate
in the early stages of the history of the pistillate flower only the
stigmas project beyond the neck of the involucre. The pistillate
flower consists of a single pistil, whose trilocular ovary terminates a
stalklike structure which is jointed below to the pedicel (fig. 32).
Soon after fertilization the stalk of the pistillate flower elongates,
causing the pistil to project from the cyathium and nearly to close
the opening of the involucre. When a stamen is nearly mature
a depression appears, marking the point of juncture of the pedicel
and the filament. Secondary staminate flowers arise as branches
from the older ones (fig. 3, s 2 ). This description of the develop-
1917]
WENIGER— EUPHORBIA
271
ment of the cyathium agrees with that given by Miss Lyon (8) for
E. corolla ta.
Embryo sac
/), which soon becomes an
integuments
formed in each locule of the ovary. Before the
to appear, the megaspore mother cell can be distinguished by the
size of its nucleus (figs. 5, 11). It is subepidermal in origin and
larger than the surrounding cells of the nucellus. After increasing
m
formation of a typical
(fig. 13), of which
innermost
the embryo sac.
inner integument
outer (oi), which appears a little later, grows the more rapidly. It
has been stated by Poisson (16), working on E. Lathyrus and
E. Peplis, and by Schweiger (20), investigating many species of
Euphorbia, that the outer integument develops before the inner-
It would be easy to arrive at a similar conclusion in the case of
E. Preslii, since one rarely obtains a preparation showing the stage
at which the inner integument is appearing at the base of the
nucellus before any trace of the outer is to be seen, and since the
outer integument grows so rapidly that it very early extends
beyond the inner. In all probability, closer study of this species
would show that in these also the inner integument begins its
development first, as is the case in E. corollata, E. Preslii, and
*
E. splendens.
At the time of the first nuclear division in the functional mega-
spore, the outer integument reaches about half-way to the tip of the
the inner integument is still extremely
integument begins to grow more rap
As
welling
Its
increase
and slender and giving to the structure
The nucellus grows out into a long beak
beyond the integuments. At this time
sac has reached the 8-nucleate stage, and
fills the snnre hptwppn thp hpaklikp. nrnl
272 BOTANICAL GAZETTE [april
the placenta, and the ovary wall. The outer integument always
extends considerably beyond the inner, even at the maturity of the
embryo sac (fig. 10). The sac becomes deeply imbedded in the
cells of the nucellus (figs. 9, 10). It is very long, and averages
about 5 or 6 /z in thickness.
The functional megaspore grows considerably (fig, 14) before
the first division of its nucleus. The other 3 megaspores disinte-
grate, but are visible at least as late as the 4-nucleate stage of the
embryo sac as small, dark-staining cells at the micropylar end of the
sac (fig. 17). The 2 nuclei resulting from the first division are
usually to be found near the respective ends of the sac (fig. 16).
In one case observed (fig. 17), however, one nucleus of each pair
had moved nearer the center of the sac. That the latter case is
exceptional is indicated by the fact that the 8 nuclei formed by
the third division lie in 2 groups of 4 each at the respective ends of
the sac. Cell division now occurs in the typical way (fig. 15).
The synergids are oval in shape and each has a characteristic
vacuole below the nucleus. The egg extends farther toward the
center of the sac than the synergids. The 3 antipodals are well
defined, angular cells, each with a conspicuous vacuole. After
cell division is completed, the polar nuclei remain for a time in what
seem to be their original positions near the respective ends of the
sac (fig. 18). In one case they were found to have
the center of the sac (fig. 19), but no case was observed in which
they had come in contact with each other previous to fertilization.
Mobile wski (13) found no evidence of a fusion of the polar nuclei
in E. virgata, which has a typical embryo sac of 8 nuclei. Hegel-
maier (6) found no fusion of either male or female nuclei, or of
polar nuclei, in E. dulcis. I found no case showing actual fertiliza-
mo\
tion. Fig. 19 shows the antipodal cells and the synergids appar-
disintegrating
male
from that observed by Miss
il nuclei are ephemeral anc
formation
It is difficult to trace the course of the pollen tubes, should they
be present, because of the long cells of the obturator. There seems
1917] WEN IGER— EUPHORBIA 273
to be little possibility for self-pollination, for the neck of the cya-
thium is very small and the staminate flowers do not extend above
the surface of the cyathium. When the embryo sac is mature,
the staminate flowers are still rudimentary. Insect pollination is
improbable because of the smallness of the cyathium and the
smallness of the opening. Seeds are formed with marked regularity,
which would hardly be the case if wind pollination occurred.
Hegelmaier (6, 7) found the same conditions with regard to pollina-
tion in E. dulcis.
Embryo
The fertilized egg divides in a plane parallel with the long axis
of the sac (fig. 20). The second division occurs at right angles to
the plane of the first (fig. 21). Further divisions result in the
formation of a globular mass of cells (figs. 22, 23, 24). In all cases
observed, the embryo formed no suspensor. The beak of the
nucellus and the obturator gradually disintegrate as the embryo
is formed, and the inner and outer integuments grow so as nearly
to fill the large opening originally constituting the micropyle,
but still leaving a small opening (fig. 25).
As early as the 2-celled stage of the embryo, endosperm nuclei
appear at either side of the embryo. In the case represented in
fig. 20, one endosperm nucleus (en) lies between the embryo and
the micropylar end of the sac. The endosperm nuclei increase
rapidly in number and are distributed quite uniformly throughout
the peripheral region of the sac (fig. 24). Cell division does not
occur in the endosperm until the embryo has come to consist of
several hundred cells. The endosperm gradually fills the space
originally occupied by the nucellar tissue (fig. 25, n).
The embryo changes as it grows from a globular (fig. 26) to an
*
elongated form (figs. 28, 29). Fig. 30 shows the earliest stage at
which cotyledons were observed. A well developed root cap is
present in the mature embryo (figs. 27, 31, re). When mature, the
embryo (figs. 27, 31) is straight and its length nearly equals that of
the seed, the root cap (re) being pressed closely against the micro-
pyle. Surrounding the embryo, except at the tip of the root cap,
i> the endosperm (fig. 27, end), whose cells contain a large amount of
reserve food material in the form of starch, fat, and aleurone grains.
274 BOTANICAL GAZETTE [april
Euphorbia splexdens
Embryo sac
The flowers of this species develop just as do those of E. Preslii,
and there is also a similarity in the general structure of the obturator
and the ovule. As in E. Preslii, the megasnore
mother cell ma\
iguished before the integuments have begu
mother cell is easily recognizable by its
times
fact that it contains a very large nucleus. It is situated 3 layers
gh in numerous
found it only in this position, it is probable that in this species also
it originates as a subepidermal cell and that the cells of the nucellus
comes to lie more deeDlv in
mo
and
STOWS
At the
moved
the micropylar end of the cell. One unusually favorable prepara-
tion showed a late anaphase of the heterotypic division (fig. 37).
The spindle in this figure occupies a central position and its long
axis lies in the plane of the long axis of the nucellus. There are
12 small, nearly spherical daughter chromosomes in each of the
2 groups on the spindle.
Although the formation of the row of 4 megaspores was not
observed, it is certain that 4 are formed, for when the functional
megaspore has increased in size (fig. 38), 3 dark-staining masses
can be distinguished at its micropylar end. This stage agrees with
the corresponding one in E. Preslii, in which it is plainly the inner-
most of the 4 megaspores that develops into the embryo sac. Thi
megaspore (fig. 38), even at the division of its nucleus, is not as
large as the megaspore mother cell. In one case (fig. 39) 2 develop-
found
the nucellus. Each has a
dark-staining mass of apparently 3 disintegrating cells at the micro
pylar end, but the number of these cannot be distinguished witl
certainty. This occurrence of 2 functional megaspores is doubtles
very unusual, for it was observed in but one ovule.
1917J WENIGER— EUPHORBIA 275
The developing embryo sac becomes deeply imbedded in the
nucellar tissue. After some growth of the functional megaspore,
its nucleus divides (fig. 40) and one daughter nucleus moves to each
end of the cell. At this stage further growth takes place, and while
the first and second divisions of the nucleus (figs. 40, 41) are taking
place, a large central vacuole is formed which persists for some
time. An 8-nucleate stage was not found. In two cases 4 nuclei
were found at the micropylar end (fig. 42), but only 3 at the antip-
odal end of the sac. In most cases in which the egg apparatus
had been differentiated, no nuclei were to be found at the antip-
odal end of the embryo sac, indicating that the antipodal nuclei
(and cells, if formed) must be ephemeral, unlike the antipodal
cells of E. Preslii. Fig. 43 shows a sac with the egg apparatus
fully formed and the polar nuclei apparently about to fuse near
the egg, while the antipodal end of the sac shows 2 daughter nuclei
of a recent division, with a cell plate between them. It is possible
that after the second nuclear division in the developing megaspore.
one of the two nuclei at the antipodal end divides some time before
the other. One of the daughter nuclei of this (the third) division
might then move to the micropylar end and function as a polar
nucleus, its sister nucleus disintegrating before the remaining
nucleus in the antipodal end (a daughter nucleus of the second
division) finally divides. This explanation would also fit in with the
condition found in the sac shown in fig. 42, which had only 3 nuclei
at the antipodal end.
Fig. 44 shows another peculiar embryo sac in which there are
plainly 8 nuclei at the antipodal end of the sac, at least 3 of which
are surrounded by cell membranes. In this case, it is conceivable
that each of the 4 nuclei at the antipodal end of the sac has divided
and that none has as yet disintegrated. In all but these cases, the
antipodal nuclei (or antipodal cells) had disintegrated. The egg
apparatus seems to be quite typical (figs. 43, 45). At first the nu-
cleus of the egg occupies the center of the cell, but later, as the egg
grows, the nucleus moves to the side of the cell farthest from the
micropyle. The egg is spherical, and its nucleus is not, in general,
larger then the nuclei of the synergids. In the sac shown in fig. 45
one of the polar nuclei lies close to the egg, while the other seems
276 BOTANICAL GAZETTE [april
to be moving along the side of the sac toward the egg. The polar
nuclei are at first not as large as the other nuclei of the sac, but
before their fusion (fig. 46) they increase in size, each becoming
larger than the egg nucleus. Fusion takes place below the egg in a
plane either at right angles to (fig. 46) or parallel with (fig. 47) the
long axis of the sac. The 2 nucleoles persist in the fusion nucleus
until fertilization takes place.
The embryo sac of E. splendens differs from that of E. Preslii
chiefly in the history of the antipodal cells, which in the latter
species persist for some time after their formation; another differ-
ence is that in E*. Preslii the polar nuclei remain in their original
positions until after cell division occurs.
If fertilization does not occur immediately after the fusion of
the polar nuclei, the synergids disintegrate, leaving the egg and the
fusion nucleus close together at the micropylar end of the sac. In
2 embryo sacs in which fertilization was observed, the synergids
were disintegrating, but their nuclei were still recognizable as
dark-staining masses. In the sac shown in fig. 48, the pollen tube
has destroyed one of the synergids and discharged one male nucleus,
which may be seen in contact with the nucleus formed by the
fusion of the polar nuclei. The latter nucleus still shows 2 nucleoles
and is considerably larger than the egg nucleus. It has already
moved a little way toward the antipodal end of the sac. The male
nucleus also possesses 2 nucleoles and is crescent- shaped. The
second male nucleus is a dark-staining mass still in the pollen tube
and little more than its nucleole can be distinguished. It is about
to pass down to the egg nucleus, the tip of the tube being within the
cell membrane of the egg. Fig. 49 shows another pollen tube
which has not yet discharged its male nuclei. It contains densely
staining material which seems to be aggregated into several masses,
but no nuclei are distinguishable. The polar nuclei in this case
have not completely fused and the egg nucleus is in a resting stage.
The pollen tube could not be traced back into the micropyle in
either case, for only its tip seems to contain material that stains
densely. With the triple stain, the contents of the tip of the tube
always take up the safranin. Fertilization does not take place
at the same time in the 3 ovules within the same pistil. A pollen
i9i 7 J WENIGER— EUPHORBIA 277
may
charging its nuclei, while in another case the endosperm nucleu-
may have undergone several divisions. Figs. 48 and 50 were drawn
from 2 embryo sacs within the same ovary.
Embryo
The fertilized egg does not divide immediately after the fusion
of the nuclei within it. Usually there are 5 or 6 nuclear divisions
perm
In the sac
erm
undivided. The first division of the egg (fig. 51) is at right
angles to the long axis of the nucellus. The developing embryo
forms a short suspensor which is several cells in diameter. The
terminal cell divides by a longitudinal wall after the embryo is about
4 cells in length (fig. 52). There seems to be nothing definite about
the planes in which later walls are formed (figs. 53, 54), but a more
£>
mass
suspensor (figs. 55, 56). In the embryo represented in fig. 56 the
suspensor seems to be disintegrating. The mature embryo has
a structure similar to that of E. Preslii, there being a well differ-
entiated root cap and epicotyl.
Summary
1. The cyathium of both species studied begins as a papilla
which arises between two bracts. The order of appearance of the
parts of the cyathium is as follows: staminate flowers, involucre,
branch
pel
2. The megaspore mother cell is subepidermal in origin in
E. Preslii, and probably also in E. splendens.
3. An axial row of 4 megaspores is formed, the lowest of which
develops into the embryo sac; the other 3 spores disintegrate.
4. The inner integument begins to develop before the outer, but
the latter grows rapidly and soon overtops the inner.
5- The mature embryo sac is long and narrow, and is deeply
imbedded in the tissue of the nucellus. In E. Preslii it has the
278 BOTANICAL GAZETTE [april
structure usual in angiosperms. In E. splendens there are peculiari-
ties in the history of the antipodal nuclei which require further
study to make definite conclusions possible. It seems probable
that each of the 4 antipodal nuclei may undergo a second
division.
7. The obturator arises as an outgrowth of the placenta. It
fills the space between the beaklike prolongation of the nucellus,
the placenta, and the ovary wall. Its cells disintegrate after the
embryo begins its development.
8. At about the time of the first division of the egg of E. Preslii,
endosperm nuclei come to lie between it and the micropylar end of
the embryo sac.
9. The embryo becomes a round mass of cells; this mass
elongates and later 2 cotyledons and a well developed root cap are
formed. The mature embryo is straight, and, except at the tip
of the root cap, is surrounded by the endosperm. In E. Preslii
no suspensor was observed; in E. splendens there is a short sus-
pensor.
This paper is the result of work carried on at the University of
Wisconsin
my sincere
University or Chicago
LITERATURE CITED
1. Baillon, E. H., Etude general du group des Euphorbiacees. Paris, 1858;
rev. in Bull. Soc. Bot. France 5:776-780. 1859.
2. Brown, R., Miscellaneous works. London. 1866 (vol. I, p. 28).
3. Capus, G., Anatomie du tissu conducteur. Ann. Sci. Nat. Bot. VI. 7: 209-
291. 1878.
4. Dessiatoff, N., Zur Entwicklung des Embryosacks von Euphorbia
virgata. Ber. Deutsch. Bot. Gesells. 29:33-39. 191 1.
De Candolle, j
Hegelmaier (6).
Hegelmaier, F..
3:71. 1827; cited by
Gesells
7- , Zur Kenntnis der Polyembryonie von Euphorbia dulcis. Ber.
Deutsch. Bot. Gesells. 21:6-19. 1913.
i9i 7) WENIGER— EUPHORBIA 279
8. Lyon, Florence, Contribution to the life history of Euphorbia corollata.
Bot. Gaz. 25:418-426. 1898.
9. Mirbel, C. F., Histoire naturelle generate et particuliere des plantes.
Paris. 1 800-1 809; cited by Hegelmaier (6).
10. Mobius, M., Microscopisches Practicum fiir systematische Botanik.
Berlin. 191 2 (pp. 107-109).
11. Modilewski, J., Zur Embryoentwicklung von Euphorbia procera. Ber.
Deutsch. Bot. Gesells. 27:21-26. 1909.
12. , Weitere Beitrage zur Embryoentwicklung einiger Euphorbiaceen.
Ber. Deutsch. Bot. Gesells. 28:413-418. 1910.
i3» , Die anomale Embryosackentwicklung bei Euphorbia palustris.
Ber. Deutsch. Bot. Gesells. 29:430-436. 191 1.
14. Pax, F., Euphorbiaceae. Engler und Praxtl, Die naturlichen Pflanzen-
familien. 5:1-119. Leipzig. 1887. .
15. Payer, J. B., Traite d'organogenie comparee de le fleur. Paris. 1857;
cited by Schweiger (20).
16. Poisson, J., Du siege des matieres colorees dans la graine. Bull. Soc. Bot
France 25:47, 60. 1878.
17- Roeper, J. A. C, Enumeratio Euphorbiarum. 1824 (pi. 1. fig. 6y)\
cited by Hegelmaier (6) .
18. Schmidt, H., Ober die Entwicklung der Bliiten und Bliitenstande von
Euphorbia. Beih. Bot. Centralbl. 22:21-69. 1907.
19- Schweiger, J., Beitrage zur Kenntnis der Samenentwicklung der Euphor-
biaceen . Flora 94 : 3 3 9-3 82. 1 905 .
20. Strasburger, Jost, Schenk, und Karsten, Lehrbuch der Botanik.
Jena. 1910 (pp. 473-477).
EXPLANATION OF PLATES XIV-XYI
All drawings were made with an Abbe camera lucida at table level, and
Leitz oculars and objectives. The following combinations were used: ocular 4,
objective 3, tube length 170 mm. (X200), figs. 1-10, 24, 28-31; ocular 4,
objective 6, tube length 170 mm. (X800), figs. 11, 23; ocular 4, oil immersion
1/16, tube length 170 mm. (X2000), figs. 12, 13, 22, 33, 41, 45~475 ocular 4,
oil immersion 1/16, tube length 212 mm. (X2600), figs. 14-21, 34~4°;
ocular i, objective 3, tube length 140 mm. (Xioo), figs. 25, 27, 32; ocular 4,
oil immersion 1/16, tube length 140 mm. (X1700), figs. 42-44, 4 8 ~5 6 -
The following abbreviations are used: b, bract; c, carpel; cot, cotyledon;
en, endosperm nucleus; en d, endosperm; i, integument; it. inner integument;
m 9 involucre; n. nucellus; 0, ovule; ob y obturator; oi, outer integument;
p, papilla; re, root cap; j*, staminate flower; s 2 , secondary staminate flower;
sg, stigma.
In all figures the micropylar end is at the top of t
42-50 are reconstructed from 2 or 3 sections each.
1
2S0 BOTAXICAL GAZETTE [april
PLATE XIV
Euphorbia Preslii. — Fig. i. — Appearance of a papilla which will develop
into a cyathium.
Fig. 2. — Staminate flowers and involucre developing at base of papilla.
Fig. 3. — Ovules appearing at top of papilla, and carpels, staminate flowers,
and involucre at base; at the left, a secondary staminate flower.
Fig. 4. — Longitudinal section of cyathium, showing 2 ovules within the
ovary, and developing staminate flowers at base of pistillate flower; integu-
ments have not yet appeared.
Fig. 5. — Nucellus, containing megaspore mother cell, but with no integu-
ments as yet.
Fig. 6.— Inner integument just appearing at base of nucellus.
Fig. 7. — Inner and outer integuments at base of nucellus; embryo sac is
developing.
Fig. 8. — Obturator appearing on placenta, and outer integument over-
topping inner.
Fig. 9. — Obturator pushing up to nucellus.
Fig. 10. — Mature embryo sac deeply imbedded in tissue of nucellus, which
has developed a beak; the long cells of obturator have filled space between
nucellus and placenta.
Fig. 11. — Xucellus, showing megaspore mother cell. • ,
Fig. 12. — Megaspore mother cell before division.
Fig. 13. — Axial row of 4 megaspores.
Fig. 14. — Functional megaspore, now deeply imbedded in nucellar tissue.
Fig. 15. — Binucleate embryo sac.
Fig. 16. — Four-nucleate embryo sac.
Fig. 17. — Four-nucleate embryo sac, with 2 of nuclei near center of sac;
an unusual condition.
Fig. 18. — Mature embryo sac.
Fig. 19. — Polar nuclei have moved nearer center of sac; synergids and
antipodal cells seem to have disintegrated.
Fig. 20. — Two-celled embryo, with endosperm nuclei; one of latter
between embryo and micropylar end of sac.
Fig. 21. — Four-celled embryo; several endosperm nuclei between embryo
and micropylar end of sac.
Fig. 22. — Embryo a globular mass of cells.
Fig. 23. — Still later stage in development of embryo.
PLATE XV
E. Preslii. — Fig. 24. — Longitudinal section of seed, with embryo at
micropylar end of embryo sac, and endosperm nuclei distributed in peripheral
region of sac.
Fig. 25.— Elongated embryo imbedded in endosperm.
Figs. 26, 28, 29, 30. — Elongation of embryo and appearance of cotyledons.
BOTANICAL GAZETTE, LXII1
PLATE XIV
•
\
1
7
i
Y
WKXIGER on KUPIK >RBIA
»
*
I
BOTANICAL GAZETTE, LXI1I
PLATE XV
-__V— rr
— {---c^rt
31
40
WEMGER on EUPHORBIA
J
1
I
BOTANICAL GAZETTE, LXIII
PLATE XVI
I
■ .
f
.\-' 4r ^r-
■
45
44
43
42
....
■
■
46
47
51
48
55
WEXIGER on EUPHORBIA
I
i9i 7] WENIGER— EUPHORBIA 281
Fig. 27. — Mature seed in longitudinal section.
Fig. 31. — Mature embryo.
Fig. 32. — Pistillate flower, with ovary jointed to pedicel.
E. splendens.—YiG. 33. — Nucellus with megaspore mother cell 2 layers
below epidermis.
Fig. 34. — Megaspore mother cell with resting nucleus.
Figs. 35, 36. — Synapsis in megaspore mother cell.
Fig. 37. — Anaphase of heterotypic division in megaspore mother cell.
Fig. 38. — Lowest of the 4 megaspores, which is to develop into embryo
sac; other 3 megaspores have disintegrated.
Fig. 39. — Two functional megaspores side by side, each accompanied by
what appear to be 3 disintegrating megaspores.
Fig. 40. — Binucleate embryo sac.
Fig. 41. — Four-nucleate embryo sac.
PLATE XVI
Fig. 42. —
antipodal end.
Fig. 43.
micropy
formed
about to fuse near micropy lar end; 2 daughter nuclei with cell plate near
antipodal end.
Fig . 44.
micro
pylar end; 8 nuclei at antipodal end, 3 of which are inclosed by cell membranes.
Fig. 45.— Polar nucleus from antipodal end approaching other polar
nucleus which lies close to egg apparatus.
Fig. 46. — Polar nuclei about to fuse near egg.
Fig. 47. — Polar nuclei fused, but 2 nucleoles still persisting; egg nucleus
at one end of cell.
Fig. 48. — Fertilization: one male nucleus in contact with nucleus formed
by fusion of polar nuclei; other male nucleus is still in pollen tube.
Fig. 49. — Pollen tube within embryo sac; no evidence of fertilization,
fuse.
distinguishable
Fig. 50. — Fertilized egg still undivided; 2 nuclear divisions have occurred
endosperm.
Fig. 51. — First division of egg.
Fig. 52. — Young embryo with terminal cell divided by longitudinal wall.
Figs. 53, 54. — Later stage in embryo development.
Fig. 55. — Embryo consists of rounded mass of cells at end of a short sus-
pensor.
Fig. 56.— Embryo has increased in size, and suspensor is beginning to
disintegrate.
THE DEVELOPMENT OF THE ASCOCARP OF RHIZINA
UNDULATA FR. s
Harry M. Fitzpatrick
(WITH PLATES XVII AND XVIIl)
Our knowledge of the earliest stages in the development of the
fruit body in the Helvellales is restricted to a limited number of
species of the Geoglossaceae and one species of the Helvellaceae.
Practically nothing is known of the ontogeny of any member of
the Rhizinaceae. The question of the origin of the h
rmenium
this family, therefore, is of considerable interest.
members of
Helvellales
inclosing membrane. In the system of classification employed by
Schroter (27) the Helvellales are separated from the other orders
of the Discomycetes on the basis of the gymnocarpous origin of the
fruit body. The statement that members of this group are never
angiocarpous, however, was evidently based upon general obser-
vations rather than upon careful study of young ascocarps, and
subsequent investigations have demonstrated its falsity. The
first evidence of the presence of a veil in this group was presented
by Dittrich (10) in connection with investigations on the Geoglos-
saceae. He discovered that in the youngest stages the fruit body
of Leotia lubrica is inclosed by an envelope comparable to the volva
of the Agaricaceae. This membrane later gelatinizes and is
ruptured by the expansion of the ascoma within. Observations
made by him on Mitrula phalloides disclosed a similar condition in
that species. His collections of fruit bodies of representatives of
the Helvellaceae, including species of Helvetia and Gyromitra.
revealed, however, no stages young enough to shed light on the
question of the presence or absence of a veil in the beginning.
Duraxd (14) in his monograph of the Geoglossaceae of North
America reviews the work of Dittrich on the development of
Leotia and Mitrula and states that observations of his own on
several different species point unmistakably to the same conclusion.
Botanical Gazette, vol. 63]
[282
1917] FITZPATRICK—RHIZINA UNDULATA 283
He has found a veil in Spathularia velutipes, Mitrula phalloides,
Microglossum viride, and Cudonia lutea. The most conspicuous
veil seen is present in Cudonia lutea and Spathularia velutipes.
It persists in both species until the plants are one-third or even
one-half grown, when it fragments into irregular pieces and falls
away. Durand publishes photographs showing very clearly the
dehiscing membrane on the hymenium of maturing plants. He
examined, however, very young ascomata of Geoglossum glabrum,
G. dijforme, and Trichoglossum velutipes without finding any trace
of such a membrane. Finally, he expresses the opinion that "when
the development of the Discomycetes shall be better understood
it will be found that in none of them, not even in the Helvellaceae,
is the hymenium exposed from the first."
More recently McCubbin (25) has studied the development of
the fruit body in Helvetia elastica, and states that, in the earliest
stages, the young ascocarp is inclosed by an envelope which later
dehisces and completely disappears. He presents photomicro-
graphs showing in median longitudinal section a single young fruit
body bearing at the periphery an adhering bit of tissue, and says
that this is a fragment of the transitory veil which earlier enveloped
the ascocarp. Although his discussion covers stages earlier than
that figured, his photomicrographs are unconvincing.
Brown (4) has studied the development of Leotia lubrica and
L. chlorocephala, but his account contains no information bearing on
the question of the presence or absence of a veil in the early stages.
Carruthers (7) describes at considerable length the cytology
of Helvetia crispa, but does not attempt to study the earliest stages
in the development of the fruit body. Massee (24) in his mono-
graph of the Geoglossaceae makes no mention of the occurrence of
a veil on any of the species in this family. So far as the writer
is aware, no other investigation on the development of the fruit
body in this order has been undertaken. No representative of the
Rhizinaceae has been studied in the young condition.
Considerable difficulty is experienced in obtaining the youngest
stages of the fruit bodies of members of the Helvellales, either by
collection or culture, and it is not surprising therefore that stu-
dents of the fungi have given little attention to developmental
284 BOTANICAL GAZETTE [april
studies in this group. Moreover, the number of species included
in the Rhizinaceae is not large, and collections of some of these
are rarely made (Underwood 29, Hone 22, Burt 6).
During the summer of 19 14 the writer discovered an abundant
supply of the apothecia of Rhizina undulata, and was able to collect
numerous very young fruit bodies in addition to the older stages.
These have furnished all the necessary material for a thorough
study of the development of the fruit body in this species. Rhizina
undulata is particularly suitable for investigation, since it is the
type of the genus and family, and probably the best known mem-
ber of the group.
Schroter (27) separates the Rhizinaceae from the Geoglossaceae
and Helvellaceae on the basis of the sessile fruit body. Boudier
(3), attempting to arrange the Discomycetes in a natural classi-
fication, has developed a system very different from that of
Schroter. He makes his primary separation on the basis of the
method of rupture of the ascus. He places in one large group
(Opercules) those forms whose asci open by an apical lid, and in
the other group (Inopercules) those whose asci open merely by a
pore. By this separation the Helvellaceae and Rhizinaceae fall
in the first group and the Geoglossaceae in the second. Boudier
regards the Rhizinaceae as more closely related to such genera as
Peziza, Aleuria, and Sarcoscypha of the Pezizales than to either
the Helvellaceae or Geoglossaceae. Lagarde (23) makes the
primary separation also on the method of rupture of the ascus.
The facts brought out in the study of the development of the
fruit body in various genera of the Discomycetes are especially
interesting for the bearing they have on the questions involved in
these two opposing systems of classification. The present inves-
tigation is undertaken with the hope that more complete infor-
mation with reference to ontogeny will render less difficult the
consideration of the phylogeny of the group.
Rhizina undulata Fr.
Historical.
(
in 1815.
prominent
celium, termed rhizoids. These are developed
1917] FITZPATRICK—RHIZINA UNDULATA 2S5
in considerable numbers on the lower surface of the fruit body, and
serve to attach it to the substratum. Representatives of this
genus, therefore, are not easily mistaken.
Rhizina undulata was apparently first described by Schaeffer
(26) under the name Elvela inflata. This writer published a
colored figure of the plant which illustrates well the more evident
characters of the species. Fries (16) later described the fungus
as Rhizina undulata, and discusses it under this name in Systema
mycologicum (17). In accordance with the international rules of
botanical nomenclature the writer designates the species by this
name, but it has more commonly been referred to in recent litera-
ture as Rhizina inflata. The plant has been described by many
writers and has frequently been figured. Excellent colored plates
are given by Boudier (2). On account of the fact that the fungus
is parasitic on the roots of certain trees its morphology and life
history have received considerable attention (Tubeuf 28).
Hartig (19, 20, 21) discusses at some length the structure of
the mature fruit body. He made no attempt to study its develop-
ment. More recently Weir (30) has published photographs of
apothecia with notes on the parasitism of the fungus. None of
these workers describes other than the mature condition.
Material and methods. — The apothecia used by the writer
in these investigations were collected in July 1914 in a small pine
wood north of Beebe Lake near the Cornell University campus at
Ithaca, New York. Due to favorable weather conditions the
fruit bodies were developing in great profusion, and dotted the
ground throughout a considerable portion of the wood. Although
no attempt was made to obtain corroborative evidence as to the
Transverse
parasitism of the species, it was noted that the fruit bcx
cases were firmly attached to the roots of living pines.
sections through pine rootlets will be noted in the accompanying
plates. In fact, the voungest fruit bodies were obtained
more
superficial
which the young fruit bodies were being differentiated. In this
immature
obtained easily. Mature apothecia were available in such abun-
dance that several quart jars of material were preserved for class
2S6 BOTAXICAL GAZETTE [april
use. The writer's determination of the fungus was confirmed
independently by E. J. Durand and F. J. Seaver, and his thanks
are due both of these gentlemen.
The young apothecia collected for the study of the develop-
ment of the fruit body were immediately placed in medium strength
They were carried into paraffin, and
m
chromo-acetic acid fixer. They were carried into
were studied in serial sections of 4-7 jx thickness,
was stained chiefly with Heidenhain's iron alum-haematoxylin, no
counter stain being used. For certain of the more mature stages
the shortened Flemming's triple stain proved more useful. The
material was sectioned and stained in the laboratories of the
Brooklyn Botanic Garden in the summer of 1915, while the writer
held a visiting fellowship at that institution. He wishes to take
this opportunity to express his appreciation of the courtesy of
Director C. S. Gager in extending to him the facilities of the
laboratories, and to acknowledge his indebtedness to Dr. E. W.
Olive for many kindnesses, including several helpful suggestions
concerning technique. The investigation was carried to comple-
tion in the laboratories of the Department of Plant Pathology at
Cornell University.
The mature fruit body. — The mature apothecia exhibit great
variation in size and shape. Considerable irregularity of contour
is characteristic, and the early fusion of several fruit bodies results at
maturity in large unsymmetrical structures. The apothecia shown
natural size in fig. 1 illustrate well the extent of variation. The
two fruit bodies in the lower left hand corner of the figure were
inverted to reveal the clusters of ropelike rhizoids which give to
the genus its name. The fruiting surface varies from a rich
chestnut to a dark brown, and when moistened is peculiarly sticky
and glutinous. Around the margin of the apothecium a sterile
zone is indicated by a narrow, white, encircling band which con-
trasts sharply with the brown hymenium. This white margin is
very evident in all stages. In the youngest fruit bodies the
entire surface is white, the brown fruiting layer later making its
appearance at the center and increasing rapidly in extent. The
smaller of the fruit bodies pictured in fig. 1 show this condition
clearly.
1
i9i 7] * FITZPATRICK—RHIZINA UNDULATA 2S7
The hymenium. — The hymenium at maturity contains 3 types
of structures: asci, paraphyses, and paraphysis-like structures
which the writer will designate as setae, since they arise far below
the hymenium, and are dark colored and thick-walled. The asci
are narrow, cylindrical to clavate, and 8-spored. The spores are
uniseriate, fusiform, hyaline, unicellular, and at maturity bigut-
tulate. The paraphyses are filamentous, unbranched, multi-
septate, hyaline, and at the apex distinctly clavate. The setae
are heavy-walled, brown, non-septate, unbranched tubes originating
far below the hymenium (fig. 11) and discharging a brown sticky
secrefion at their tips. This secretion flows over the surface of the
hymenium made up of the swollen tips of the paraphyses, and gives
a condition superficially resembling an epithecium. Hartig
(20, 21) states that it is impossible to procure a pure culture from
the spores of this fungus on account of the bacteria which swarm
in myriads in this glutinous secretion and find their way down
between the paraphyses. These bacteria induce a rapid decay of
1
the entire apothecium, and give to it in age a peculiar water-soaked,
brittle consistency. In fig. 13 a portion of the hymenium is shown
at a stage approximating maturity. The broad, deep-staining
tubes are the setae. Surrounding these are the paraphyses, and
pushing up from below may be seen the young, uninucleate asci.
The swollen tips of the paraphyses are obscured by the layer of
deep-staining glutinous material.
Mycelium. — The mycelium of Rhizina undidata possesses more
than ordinary interest for the systematise It is described by
Hartig (21) as bearing clamp connections. He says: " Although
I have much diffidence in maintaining that this feature, which
otherwise is peculiar to the Hymenomycetes, is characteristic of.
this parasite, still I cannot doubt that these filaments with clamp
cells belong to it" The writer has given the mycelium careful
examination, and has been unable in his collections to find clamp
connections on hyphae certainly belonging to the fruit bodies of
Rhizina. He does not feel, however, that sufficient investigation
of this point has been carried on to enable him to state definitely
that they never occur. The mycelium develops profusely, and
covers the soil particles and small rootlets as a whitish, moldlike
2SS BOTAXICAL GAZETTE [april
growth. Upon this subiculum compact masses of hyphae develop
as minute, snow white knobs. These represent the primordia of
fruit bodies.
Development of the ascocarp. — The youngest fruit body
sectioned measures slightly less than 0.3 mm. in lateral diameter.
A considerable number of others possess a maximum diameter of
1 mm. or less. The youngest fruit body studied (tig. 2) is a wholly
undifferentiated "button" of mycelium. The hyphae making up
the primordium arise in this case from about a small rootlet, and
pushing upward between other rootlets run more or less distinctly
parallel toward the surface of the ground, where they radiate in
every direction, giving the primordium its rounded form. At this
early stage there is no indication of sexual cells, and no evidence
other than shape that this "button" of mycelium is to develop
into a fruit body.
The hyphae at the surface of the primordium form a more or
less definite palisade layer, although at this early period they are
sufficiently flexuous to destroy the very definite palisade effect
evident later. These hyphae in many cases can be traced backward
with ease to the point of origin of the fruit body. No structure
of the nature of an enveloping veil is present, and it is incredible
that one could have existed at an earlier period. Neither in this
nor in any later stage has the writer been able to find remnants
of a ruptured envelope such as that figured by McCubbin (25) for
Helvetia elasiica. He has searched for these in sections of many
very young fruit bodies and is absolutely convinced that in Rhizina
undulata the ascocarp is at no stage provided with a veil. The
fruit body is therefore gymnocarpous and the hymenium is " exposed
from the first." Fig. 2 shows in median longitudinal section a
fruit body of Rhizina undulata considerably younger than the
youngest stage photographed by McCubbin in Helvetia. The
deep-staining spots at the side and base of the primordium are
transverse sections of pine rootlets.
McCubbin states that in Helvetia elastica "the envelope which
covers the fruiting body in its early stages arises from the palisade
layer. Many of the club-shaped hyphae of the latter continue to
grow out beyond the general surface, then turn at right angles,
>
1917] FITZPATRICK—RHIZINA UNDULATA 289
and interlacing in every direction along the surface form a matted
web 2-8 threads in thickness. This membrane is very transitory,
however, and undergoes degeneration at an early period. .Its
protoplasm takes on a granular appearance, the cell outlines
become indistinct, and finally the whole disintegrates into a
deeply staining mass in which the nuclei are the most prominent
feature. Long before the process is complete, however, the rapid
growth of the underlying tissue bursts the envelope so that it
adheres in flakes (figs. 57, 58). Then the paraphyses and inter-
calary palisade hyphae pushing out to the surface complete the
separation and all traces of it are cast off."
McCu
m
crographs of stages younger than that shown in his fig. 57. If
in Helvetia, as he states, the envelope, which incloses the fruit
body in the early stages, arises from the palisade layer, it might be
concluded that the section of Rhizina undulata shown in fig. 2 is
too young to possess the envelope, and that it might logically be
expected to develop later on older fruit bodies. That it does not
do so, however, is certain. The writer has had available a suf-
number
mi
to this point.
No veil or fragm
bodies sectioned.
Figs. 3-6 show median longitudinal sections through primordia
ma
somewhat older than that pictured in fig. 2. The
the 5 cases is the same, being 40 diameters. Other fruit bodies
sectioned, of intermediate sizes, bring out no additional facts.
In fig. 3
hyphal arrangement at the
m 9
periphery is evident. The deep-staining area on the upper surface
gm
/ in trimming the print. Other
sections of similar rootlets appear at different places in the interior
of the fruit body. At the base of the ascocarp can be noted the
tendency of the mycelium
These young
rhizoids appear in section in figs. 3, 5, and 6. Fig. 5 shows the
palisade layer of hyphae very clearly. In fig. 10 a portion of the
same
2go BOTANICAL GAZETTE [april
in fig. 5 is shown much enlarged. It will be noticed here that the
tips of the hyphae at the periphery stain very deeply. This is
probably due to the fact that, since growth is taking place much
more
much
ns as the result of metabolism more deeply staining contents,
certain young fruit bodies (fig. 4) the setae are developed
earlier than in others. The reason for this is not known.
They are prominent organs, originate from the deeper lying tissue
of the fruit body, and protrude beyond the palisade layer as deep-
staining spines. These are shown much enlarged in fig. 14. It
will be noted that they are of much greater diameter than the
other hyphae of the ascocarp. They arise as differentiations of
ordinary vegetative hyphae.
Sexuality. — Near the center of the sections shown in figs. '
and 5 are to be seen deep-staining elements. These bodies con-
stitute the sexual apparatus of the fungus, and at a somewhat
later stage (fig. 9) give rise to the ascogenous hyphae. Since the
writer is engaged in the preparation of another paper dealing with
the details of the sexual process in Rhizina undulata, he will refrain
from further comment on these structures at this point.
Paraphyses. — The layer of paraphyses is developed compara-
tively early in the history of the fruit body and constitutes a well
m •
defined zone long before the asci are produced. Fig. 7 shows a
median longitudinal section through a young apothecium on the
upper surface of which the layer of paraphyses is being differ-
entiated. In fig. 8 this same layer is shown more highly magnified.
The paraphyses arise from the ordinary hyphae in the interior of
the fruit body, and are in reality a specialized portion of the palisade
layer. As the fruit body enlarges by the elongation and branching
of the hyphae at the periphery, those palisade hyphae which lie on
the upper surface increase in number, run more nearly parallel,
and come to stand very close together. They soon constitute a
well defined zone, the individual units of which appear straighter,
slightly narrower, and many times more abundantly septate than
the palisade hyphae covering the remainder of the fruit body.
This layer of paraphyses continues to develop at the margin as the
fruit body increases in diameter, the line of demarcation between
1917] FITZPATRICK—RHIZINA UXDULATA 291
paraphyses and palisade hyphae at the point of contact never
being very sharp. Fig. 9 pictures approximately one-half of a
median longitudinal section through an older fruit body in which
the layer of paraphyses has become sharply differentiated from the
tissue of the fruit body below. The rounded sterile margin of the
f apothecium is here evident.
, Ascogenous hyphae. — Immediately beneath the paraphyses is
a deeper-staining zone filled with the ultimate tips of the profusely
branching ascogenous hyphae. These hyphae have their origin
near the base of the fruit body in the sexual apparatus previously
mentioned, and may be seen ramifying throughout the interior of
the ascocarp as they branch and rebranch on their upward journey
toward the hymenium. ' At this stage these threads have not yet
undergone crozier formation at their tips, and no young asci are
present. Fig. 12 shows a section through the hymenium of a more
mature apothecium in which the young asci are pushing up among
the paraphyses. The septate paraphyses, the tubular setae, and the
oung, deep-staining, clavate asci show here to good advantage.
In fig. 13 the asci are shown at about one-half their mature size,
and the fusion nucleus may clearly be seen in each. In this and
other sections the deep-staining glutinous secretion previously
discussed forms a well defined layer above the clavate tips of the
paraphyses.
General considerations
The results of the present investigation on the origin and devel-
opment of the ascocarp in Rhizina undulata are particularly interest-
ing in the light of the facts disclosed by various workers on other
allied forms. Before the publication of the work of Dittrich
(10) on the development of Leotia lubrica and Mitrula phalloides,
it was generallv assumed that in the 3 families of the Helvellales
v
the fruit body is gymnocarpous. After the appearance of Dit-
trich 's paper the pendulum of opinion swung to the other extreme,
and we find the statement made by Durand (14) that in his
opinion "when the development of the Discomycetes shall be
better understood it will be found that in none of them, not even
in the Helvellaceae, is the hymenium 'exposed from the first/"
It is evident now from the results of researches on various
•
292 BOTAXICAL GAZETTE [april
Geoglossaceae that certain members of this family are at first pro-
vided with a veil. It is equally certain that in Rhizina iindulata
no enveloping membrane is ever present. Both conditions occur
therefore within the order. Whether it will prove possible to
separate the families of the orders on the basis of the presence or
absence of a veil is doubtful, but additional investigations on /
members of the 3 families will be necessary to determine this point.
Since the work of McCubbin (25) on Helvetia elastica is the only
contribution of any importance to our knowledge of the develop-
ment of the fruit body in the Helvellaceae, it is desirable that
other representatives of this family be studied. Also, since
McCubbin has stated definitely "from observations on a very
complete series of stages that Ceoglossum hirsutum shows no trace
whatever" of a veil, it is desirable that photographs be published
demonstrating the gymnocarpous nature of the ascocarp in this or
other members of the Geoglossaceae in which a veil is absent at
all stages. Finally, the development of the fruit body in additional
species of the Rhizinaceae should be studied to determine whether
the conditions described for Rhizina iindulata are typical of the
entire family.
It has become increasingly evident since the publication by
Schroter (27) of his system of classification of the Discomycetes
that his basis for the separation of the Helvellales from the other
orders of the group is untenable. Not only has it been demon-
strated that in certain of the Helvellales the fruit body is angio-
carpous, but also in the Pezizales it has been shown that certain
species possess a fruit body which is clearly gymnocarpous. As
representatives of this latter group may be enumerated Ascodesmis
(Claussen 8), Pyronema confluens (Harper i8, Claussen 9*
et ah), Lachnea stercorea (Fraser 15), L. scutellata (Brown 5),
and Ascobolus magnificus (Dodge ii, 12, 13). The presence or
absence of a hyphal envelope, therefore, cannot be used to separate
the Helvellales and Pezizales as constituted by Schroter, and
some other system of classification of the Discomycetes must be
employed. That of Boudier (3) has met with considerable favor.
As pointed out by Dodge (13) and Atkinson (i), several well
defined types of ascocarps are present in the Ascomycetes, and these
1917] FITZPATRICK—RHIZINA UNDULATA 293
should be considered in any system of classification. The somewhat
loose use of the terms "angiocarpous" and "gymnocarpous" and
of the phrase "hymenium exposed from the first'' has resulted,
however, in some confusion. In some species (for example Leotia
lubrica) the ascocarp is at the beginning inclosed by an envelope
which is transitory and disappears before the hymenium is formed,
while in others (for example, Rhizina unditlata) it lacks at all stages
any indication of a veil. In both cases the hymenium is " exposed
from the first," but the development of the fruit body is essentially
different, and if the veil has any phylogenetic significance the two
forms cannot be regarded as closely related. Dodge (13) states
that "the real question as to whether an ascocarp is to be classed
as open or closed in its early stages depends upon whether the
young hymenial layer arises endogenously, as in Ascobolus fur-
furaceus, or is from the first free and exposed, as in Pyronema" It
seems to the writer of greater significance to determine whether
the ascocarp is itself at any stage inclosed by an envelope. This
is certainly true from the standpoint of phylogeny.
Summary
my
the smaller rootlets of pines and other
moldlike growth. Upon this subiculum
masses
knobs. These constitute primordia of ascocarps.
2. The ascocarp primordium in the youngest stages shows no
evidence of a sexual apparatus. It is made up of undifferentiated
hyphae, which at its surface form a palisade layer.
3. The ascocarp is neither at the beginning nor at any subsequent
period provided with a hyphal envelope. The fruit body is there-
fore gymnocarpous and the hymenium is "exposed from the first."
4. There is developed in the interior of the young ascocarp a
w r ell defined sexual apparatus from which the ascogenous hyphae
arise. The details of the sexual process have been studied and
will be described in a later paper.
5. The ascogenous hyphae branch repeatedly and undergo
crozier formation in the development of the young asci.
2g4 BOTAXICAL GAZETTE [april
6. The paraphyses are a differentiation of the palisade layer
which covers the fruit body at all stages.
7. In the ascocarp of this species there are present paraphy sis-
like structures which arise early in the history of the fruit body.
They are non-septate, thick- walled tubes which originate far
down in the hypothecium, traverse the hymenium, and discharge
a brown, glutinous secretion at their tips. The writer has applied
«„a- „ yy
The
to these the term setae.
8. At maturity
brown hymenium is bordered by a sterile white margin.
9. There are present on the lower surface of the ascocarp
numerous prominent rhizoids.
' Department of Plant Pathology
Cornell University
LITERATURE CITED
1. Atkinson, G. F., Phylogeny and relationships in the Ascomycetes. Ann.
Mo. Bot. Gard. 2:315-376. 1915.
m
3. — , Histoireet classification des Discomycetes d' Europe. Paris. 1907.
4. Brown, W
Bot. Gaz.
M
5* " — ■, The development of the ascocarp of Lachnea scutellata. Bot. Gaz.
52:273-305. pi. 9. figs. 51. 1911.
6. Burt, E. A., A list of Vermont Helvelleae with descriptive notes. Rhodora
1:59-67. pi. 4. 1899.
7
cytology
Ann. Botany 25:243-253. pis. 18, 19. 191 1
Claussen, P., Zur Entwickelungsgeschicht<
Bot. Zeit. 63:1-28. pis. 1-3. figs. 6. 1905.
Boudiera.
9« , Zur Entwickelungsgeschichte der Ascomyceten. Pyronema con-
flucns. Zeitschr. Bot. 4:1-64. pis. 1-6. figs. 13. 1912.
10. Dittrich, G., Zur Entwickelungsgeschichte der Helvellineen. Cohn's
Beitrage zur Biologic der Pflanzen 8:17-52. pis. 4,5. 1898.
11. Dodge, B. O., Artificial cultures of Ascobolus and'Aleuria. Mycologia
4:218-222. pis. 72-73. 1912.
12. , Methods of culture and the morphology of the archicarp in cer-
tain species of the Ascobolaceae. Bull. Torr. Bot. Club 39:139-197*
pis. 10-13. figs. 2. 191 2.
13* 1 The morphological relationships of the Florideae and the Asco-
mycetes.
fig
1917I FITZPATRICK—RHIZINA UNDULATA 295
14. DlJRAXD, E. J
6:387-477. pis. 5-22. 1908.
Annales Mycologici
15. Fraser, H. C. I., On the sexuality and development of the ascocarp in
Lachnea stercorea. Ann. Botany 21:349-360. 1907.
16. Fries, Elias, Observations mycologicae 1:161-162. 1815.
17. , Systema mycologicum 2:33. 1822.
18. Harper, R. A., Sexual reproduction in Pyronema confluens and the mor-
phology of the ascocarp. Ann. Botany 14:321-400. pis. ig-21. 1900.
19. Hartig, R., Untersuchungen uber Rhizina undulata. Bot. Centralbl.
45:237-238. 1891.
20. , Rhizina undulata Fr. Der Wurzeischwamm. Forst. Naturw.
21.
Zeitschr. 1:291-297. 1892.
, Text-book of the diseases of trees. Transl. by W
figs
22. Hoxe, Daisy S., Minnesota Helvellineae. Minn. Bot. Studies 3:309-321.
pis. 48-52. 1904.
23. Lagarde, J., Contribution a Petude des Discomycetes charnus.
Annales
figs
24. Massee, G., A monograph of the Geoglossaceae. Ann. Botany 11:225-
306. pis. 12, 13. 1897.
25. McCubbix, W. A., Development of the Helvellineae. I. Helvetia elastica.
Bot. Gaz. 49:195-206. pis. 14-16. 1910.
26. Schaeffer, I. Ch., Fungorum Bavariae et Palatinatus Icones. pi. 153.
1800.
27. Schroter, J., Helvellineae, Pezizineae; in Engler and Pkanttl's Die
natiirlichen Pflanzenfamilien i 1 : 162-243. 1894.
28. Tubeuf, Karl von, Diseases of plants induced by crytogamic parasites.
Eng. ed. by W. G. Smith. London. 1897 (pp. 272-274. figs. 144-147).
29. Underwood, L. M., On the distribution of the North American Hel-
vellales. Minn. Bot. Studies 1:483-500. 1896.
30.
4:93-96. pi. 8. 1915.
Rhizina inflate* J
EXPLANATION OF PLATES XVII AND XVIII
undulata
shape
white margin on both young and old plants, and tendency for adjacent fruit
bod
/ — — — — — — — — — — f-j — i --
show lighter colored, lower surface and dense clusters of stout rhizoids which
serve to attach the fruit body to substratum.
Fig. 2.— Median longitudinal section through a very young ascocarp
primofdium, X40; note pine rootlets in section at side and base.
Fig. 3.— Median longitudinal section through a somewhat older fruit
body, X40; deep-staining body at periphery above is fragment of section
296 BOTANICAL GAZETTE [april
through a pine root such as those shown in the lower half of fruit body; deep-
staining structures near center of section are sexual cells which later give rise
to ascogenous hyphae; at base young rhizoids are shown in section.
Fig. 4. — Median longitudinal section through a young fruit body in
which setae have developed early, X40; these may be seen projecting above
■
layer of palisade hyphae.
Fig. 5. — Median longitudinal section through a young fruit body, X40;
palisade layer of hyphae at periphery shows plainly; note sexual cells at
center of section.
Fig. 6.— Median longitudinal section through a slightly older fruit
body, X40.
Fig. 7. — Median longitudinal section through a somewhat older fruit
body in which the layer of paraphyses is being differentiated from palisade
layer, X29.
Fig. 8. — Layer of paraphyses shown in fig. 7 enlarged to show structure
more clearly, X40; note indefinite line of demarcation between layer of
paraphyses and palisade layer of sterile margin. ♦
Fig. 9. — Approximately one-half of a median longitudinal section through
considerably older fruit body, X32; note well defined layer of paraphyses,
sterile margin, and definite, deep-staining zone below the paraphyses made up
of tips of ascogenous hyphae; ascogenous hyphae can be seen originating
near base of apothecium and branching profusely as they ramify throughout
the fruit body and approach hymenium.
Fig. 10. — Portion of section such as presented in fig. 5 enlarged to show
structure of palisade layer, X192; note deep-staining tips of hyphae.
Fig. 11. — Longitudinal section through young hymenium of fruit body
of about the same age as that shown in fig. 9, X 192; note numerous prominent
setae originating below hymenium; note also deep-staining layer at tips of
paraphyses, resulting from glutinous secretion poured over hymenium by
setae.
Fig. 12. — Longitudinal section through immature hymenium of fruit
body somewhat larger than that shown in fig. 9, X192; note slender, septate
paraphyses, prominent tubular setae, and young deep-staining asci.
Fig. 13.— Longitudinal section through hymenium of fruit body approach-
ing maturity, X192; asci have not yet formed spores; fusion nucleus is
visible in some cases.
Fig. 14. — Portion of section given in fig. 4 enlarged to show setae at
margin of fruit body, X192; note that they are much larger in diameter and
more deeply staining than the hyphae of palisade layer.
BOTANICAL GAZETTE, LXIIf
PLATE XVII
*
9 J- M. '- .
2
r
*
&&& -irr
FITZPATRICK on RHIZIXA
BOTANICAL GAZETTE, LXlII
PLATE, XVltl
s
¥
T
FITZPATRICK on RHIZI.VA
• -"
PROBLEMS OF PLANT PATHOLOGY
F. L. Stevens
Plant pathology is primarily and essentially an economic
subject, and it is mainly from this viewpoint that it will be con-
sidered in this paper, attention being called also to the relation
which the practice of pathology bears to science. The chief
application of plant pathology is to agriculture, and as so applied
the main, practical achievements may be summarized briefly as
follows: (i) the control or partial control of various fungi, notably
of orchard, vineyard, truck, and floral crops by sprays of copper
compounds; (2) the substitution in many instances, notably on
drupaceous hosts, of lime-sulphur compounds; (3) treatment by
excision and the introduction of so-called tree-surgery; (4) the
avoidance of susceptible varieties, for example, carnations, pears,
strawberries, chrysanthemums, cowpeas, asparagus, and can-
taloupes; (5) the development or utilization of disease-resistant
or partially resistant strains, for example, asparagus, pears, water-
melons, cowpeas, oats, wheat, flax, and cabbage; (6) the prevention
of disease through knowledge of necessary alternate hosts, for
example, pomaceous rusts; (7) the prevention of disease intro-
duction by quarantine and inspection; (8) prevention through
knowledge of mode or time of infection, or mode of transference,
for example, certain cereal smuts, bean and cotton anthracnose,
cabbage blackrot, and potato scab.
In this enumeration, the first 5 captions cover the major part
of the early fruits of pathology, the easily gathered fruits, first
ripe, and which could be harvested without deep, scientific knowl-
edge. Such practices do not necessarily rest upon subtle principles,
but are rather the outcome of cut-and-try methods of experience.
The accident which led to the experiments which in turn
brought into prominence the use of copper sprays and thence led
to much that has been done to perfect sprays and dust applications
'Paper presented at the Botanical Conference held in connection with the
Quarter-Centennial Celebration of the University of Chicago, June 1916.
297] (Botanical Gazette, vol. 63
298 BOTANICAL GAZETTE [april
is well known; also the taking over of the lime-sulphur mixture
from the entomologist. The susceptibility of certain varieties of
farmer
some
berries. The florist, likewise, has been obliged to eliminate certain
varieties of carnation. They would have done so had no science
ogy existed. Similarly, many
farmer
highly resistant or are of such poor quality that they are not used
extensively.
pessimistic
of science to plant pathology, I shall say at once that though these
£3
made in the main empiric
>d and made easier bv the f
fostered by basic knowledge in mycology, bacteriology, and
physiology; and definitely aided by a
special technique. With the remaining
ances
upon science is direct and evident. For example, knowledge of the
alternate host relation in pomaceous rust and currant rust could
not have been attained without the upbuilding of a broad knowledge
of the rusts in general, indeed of the fungi as a whole; nor could
the canker relation in apples (Glomerella, Sphaeropsis, Bacillus)
have been found without knowledge of the nature and morphology
of the causal fungi ; and the same is true of the present troublesome
citrus canker. Adeouate Quarantine insnert.inn
measures
without definite knowleds
causes of disease.
looms
mi
interstate and international. The following are examples of
mi
pear blight, asparagus rust, grape anthracnose, cabbage club root,
potato wart, potato blight, grape blackrot and downy mildew,
chestnut bark disease.
Seed transference of disease is exemplified in the cabbage
and
It
is barely possible, but not at all probable, that this relation could
have been discovered without intimate knowledge of the causal
1 9 1 7] STE YENS— P LA NT PA T HO LOG Y 2 99
agents, but it really was a rigid, scientific method which gave us our
present knowledge of these diseases. The valuable results of the
work on cereal smut infection furnish a fine example of achievement
in disease-prevention that could not have been attained without
both basic knowledge in mycology and a technique enabling
trustworthy experimentation.
Upon entering a new biological territory, the first work is to
collect and to classify, to know the material. So in the new field
of plant pathology much of the early work was descriptive.
The number of important plant diseases that are reasonably
well described in two volumes of the Report of the United
States Department of Agriculture for the years 1887 and 1888 is
remarkable.
While the descriptive period in plant pathology is not entirely
past, trivial diseases of cultivated plants, weeds, and wild plants
still remaining undescribed, there have been very few really impor-
tant diseases of general interest recently discovered in this country,
few which compare in importance with the apple bitter rot, tomato
leaf spot, onion smut, potato blight and scab, the cereal rusts or
smuts. Many of the diseases recently described are of minor
importance or are at present of very narrow geographic range;
some have never been noted except by those who described them.
With the general principles of treatment established and the
field for discovery of new diseases dwindling in importance, the
time has now come when further progress, with rare exception,
must be the outcome of fundamental, special knowledge and crucial
experiments. It is evident that the easy crop from the virgin
soil has been harvested, and that now we are entering upon the era
of intensive cultivation.
The conquests of the future will be mainly the result of intensive
study of the diseases and disease agents now known. Compare
the degree of thoroughness of our knowledge of any one plant
disease with any one disease in medicine. For example, compare
from the research viewpoint our knowledge of Pseiidomonas
campestris with that of Bacillus typ hosts; of the morbid histology
of wheat rust with that of diphtheria; of the "epidemiology" of
any plant disease with that of any human disease. Of course, the
300 BOTAMCAL GAZETTE [april
parallel is not fair, since the values are not commensurate, but it
serves to make the point that if such knowledge in medicine is
probably contributory to prevention, probably it is also con-
tributory in our science.
Thoroughness such as is attained in human pathology is in
reality manifestly impossible for several reasons, one being the
large number of plant diseases. Each plant species, to an extent,
has its own fungous parasites; there are more than 40 listed for
the apple alone. There are, perhaps, between 300 and 400 really
significant, economic plant diseases, and to master knowledge of
these is a great undertaking which is far from realization as yet.
*
Parasitic diseases present two chief elements, the host plant and
the parasite. There is also, what is perhaps more important, the
interrelation between these two, and what is also very important,
the relation between these two and the factors of environment.
It is with the study of these 5 elementary factors that pathology
has to do. Large attention in the past has been given to the para-
site, and in many cases it is the parasite alone which has been
studied. Proportionately little study has been given to the rela-
tions existing between the host and the parasite, while the relations
existing between environment and host, and environment and
parasite, unquestionably of great significance, present a compara-
tively unworked field.
I wish to call attention briefly to the types of problems that
exist under the above analysis. Perfecting and stabilizing of the
taxonomy and nomenclature of the parasites are of course of
fundamental value to pathology. The limitation of the families
confe<;cpd1v artificial: the
main
ithin
is really satisfying. To illustrate, the form genera Penicillium
and Coremium are separated by ordinal rank, yet a single culture,
dependent upon conditions, may give the characters of one or the
other. Ordinal questions occur regarding Meliola, Thielaiith
Fusarium. Actinonema, Helminthosporium, and many other genera.
Examples of problems in generic limitation are the Phoma-
Phyllosticta, the Septoria-Rhabdospora-Cylindros port urn, the Meli-
ola-Capnodiiim-Apiosporiiim-Antennaria questions. Within the
1917] STEVENS— PLANT PATHOLOGY 301
genus a good example is Septoria with 1200 species, or Phyllosticta
with 1 1 50 species. The former has nearly 700 species between
20 and 50 ijl in spore length. The latter has 128 species with spores
*
measuring 5-6^ long. Septoria has 115 species on Compositae,
and 77 species on the Gramineae (26 of these are within the limits
of 20-40 /j, in spore length) .
Our present knowledge of such genera, as given by Saccardo, is
essentially that of a preliminary cataloguing of these forms by
their hosts, the necessary first step. And we may add, as examples,
the species of such genera as Photna, Rhabdospora, Cercospora,
Nectria, Sclerotinia, Guignardia, Physalospora, and Phyllachora.
The bearing of this condition upon practice is evident, since
numerous forms described as separate species upon the same
economic host plant in reality may be identical or may be co-
specific with forms described as distinct species or as belonging to
other genera, families, or orders on the same or other hosts. The
next step, well exemplified by such work as the monographs of
Theissen, will consist in morphological comparison and readjust-
ment of the species. This raises the question of life histories, of
course, and shows the need of much such work as that of Shear
and Wood on Glomerella, Higgins on Cylindrosporium (Coc-
comyces), Clinton on Venturia, Wolf on rose black spot (Diplo-
carpon), etc.
In connection with these problems arises the question of host
relation and of biological specialization, as best exemplified, per-
haps, in the rusts and the powdery mildews. What is the status
of such specialization in the Fungi Imperfecti, in Phyllosticta,
Septoria, Cercospora, etc., in the Ascomycetes, Nectria, Sclerotinia,
Phyllachora, and many other genera? This forms a large and
enticing field, in which much good work has been done, but a vast
amount remains still to be done.
Coupled with these problems, come of necessity physiological,
morphological, and cytological studies. The Oospora-Actinomyces-
Streptothrix problem will require, apparently, all the possible side-
lights before solution. This illustrates admirably the dependence
of practice upon science, since fundamental questions of practice
must rest their answer upon the degree of biological specialization
o
02 BOTANICAL GAZETTE [april
and variation of this organism, which causes potato scab, and
concerning which we cannot decide as yet whether it belongs to
the Eumycetes or to the bacteria.
Morbid histology of the various diseases presents a large field
for activity. Concerning many diseases our knowledge in
regard is as yet really nil. It may be in many cases that
this
has done so. Its
tree surgery, etc.
many
smuts
The whole question of disease-resistance and susceptibility is
fundamental and
the
mechanical
the factors of air, soil, or heredity causing variation in resistance,
and the possibility of artificially changing these factors. Breeding
em
mg
the needs of cultural conditions, and laws of breeding. Notable
progress has been made with many crop plants, as oats, cabbage,
melon
some
t of much study.
It is, of course,
in many cases with
seems also sadly in need of study by those with sound ecological
training. Indeed, an ecological study of certain plant parasites,
with analysis of the environmental factors and with environments
under experimental control, touching also upon seasonal relations,
should be very productive. Problems abound on the border
fields between mycology, physiology, ecology, and pathology
relating to the age relation to disease, to mode of infection, to the
climatic and seasonal relations of the parasite, to increase and
decrease of susceptibility with, changes of environment, to the
results of varying the mass of the inoculum, and to change of the
virulence of the pathogen with environment.
Epidemiology (to borrow the term from medical usage) is
clearly linked with these topics. There is a vast amount of uncor-
related information in the literature concerning the relation between
temperature, rainfall, etc., and various diseases, but there is ample
302
j50r.LV/C4L GAZETTE
[APRIL
and variation of this organism, which causes potato scab, and
concerning which we cannot decide as yet whether it belongs to
the Eumycetes or to the bacteria.
Morbid histology of the various diseases presents a large field
for activity. Concerning many diseases our knowledge in this
regard is as yet really nil. It may be in many cases that such
knowledge will not affect practice, but in many cases it surely
has done so. Its utility appears clearly in relation to cereal smuts,
tree surgery, etc.
The whole question of disease-resistance and susceptibility is
and
the
mechanical
the factors of air, soil, or heredity causing variation in resistance,
and the possibility of artificially changing these factors. Breeding
for disease-resistance is a special problem of extreme importance,
involving knowledge of the factors of resistance and susceptibility,
the needs of cultural conditions, and laws of breeding. Notable
progress has been made with many crop plants, as oats, cabbage,
asparagus, cantaloupes, carnations, flax, melons, and cowpeas.
Hibernation of the parasite has been the subject of much study.
some cases it offers the key to prophylaxis. It is, of course,
In
inseparably linked in many
seems also sadly in need of
training. Indeed, an ecolog
sound
e>
environments
expenmen
should be very productive. Problems abound on the border
i9i 73 STEVENS— PLANT PATHOLOGY 303
room for a complete "epidemiological" study of any one of many
really serious diseases.
A large field involving knowledge of extreme value and demand-
ing ingenuity of experiment is that of pathogen transference. We
know a little about transference by insects, but very little about
wind and other agents.
Fungicides and their action are in need of more study. It
is remarkable if accident has really given us the best fungicides in
copper sulphate and lime sulphur. Our knowledge of their action
and of their composition can be increased; so, too, the time to
apply them and the strength to use. The exact time of application
is undoubtedly of much importance; in some diseases, notably
apple rust, the variable results are presumably linked with the
time relation. Exact knowledge of such relation is needed in
many cases. The subject of fungicide injury to fruits or foliage
also arises here.
There are many diseases which have been described in a pre-
liminary way, the causes of which are not yet known. Some of
these are of great injury, notably the various so-called "mosaics,"
peach yellows and rosette. Their list is essentially included in the
com
It is
for
not too much to hope that some of these will give up their se
under proper attack; some seem to have done so recently;
example, beet curly- top and the crown-gall. The status of others,
such as Jonathan spot, tomato blossom-end -rot, tobacco mosaic,
and numerous other mosaics, is not so clear. There is here opportu-
nity for good descriptive work that we may know definitely with
what conditions we have to deal. When the anatomical, histo-
logical relations are definitely recorded, we shall at least be able to
classify these various types, and to know, for example, whether
mosaic
or different nature. Abnormal enzyme
planation
s
lack conclusiveness, and certainly lack practical application.
remark
I have
desired rather to indicate the need of intensive, thorough study
ems
304 BOTANICAL GAZETTE [april
of the field and of the diversity of research material. It is evident
that no one person, either by temperament, inclination, or equip-
ment, is fitted to investigate in all of these fields. The range is
broad, and with a veritable wealth of research material, and a
survey of the past shows that the well worked subject often is
just as productive of results as an apparently much fresher subject.
For years the powdery mildews have been introductory subjects
in mycology. The group has been thoroughly monographed, col-
lected, listed, years devoted to their biological specialization,
treatments devised, etc. The field appeared too thoroughly
worked to be promising of large results; yet recent studies have
revealed the bud-scale hibernation habit of certain of these, and
thus added fundamental knowledge useful in prophylaxis.
Finally, the diseases themselves, not the fungi, need classifica-
tion. Various classifications have been used, as to cause, as to
host, etc., but these do not serve to emphasize relationships of
conditions w r hich it is of service to know.
Aside from the non-parasitic diseases, those caused by improper
abnormal
unknown
and considering only those known to be caused by parasitic fungi,
there are certain groups of conditions which stand out strongly
marked as being similar. It is of distinct advantage in studying,
m teaching, and in devism
nize and define these catep-
similarity
diseases have gravitated together; for example, the vascular
diseases, fungous or bacterial diseases, with plugging of the bundles,
popularly and very properly call the "wilts."
It is interesting to note that one of the most significant con-
tributions along this line appeared in one of our elementary texts;
significant, too, that this contribution should come from one not
primarily interested in pathology. Coulter, in his Elementary
studies in botany, gives us the conception of three general categories
of plant diseases: (i) those in which the narasites kill the living
mi
in which the parasite does not kill the living
in association with them
as
tliose in which
'
1917I STEVENS— PLANT PATHOLOGY 305
mushroom
and live in the sap; as cabbage, cucurbit, and
and
part of this paper which may lay any claim to originality, would
present the following suggestions as a step toward a classification
of plant diseases caused by fungi, separating them into the following
categories:
Wilt diseases due to m
bundles by parasites. These may be called cases of embolism; for
and Acrostilagmus
campestris
2. Disintegration of the xylem structures; for example, the
ious wood rots due to Thelephora, Hydnum, Porta, Poly poms.
phyllitm
tained within
asm of the host cell. This is the strictest type of parasitism,
example, diseases due to Synchytrium.
parasitism; for
from
living cells by haustoria, which may be called endocellular haustorial
parasitism; for example, diseases due to Phyllactinia, Peronospora,
Albugo y and Plasmopara. In this group the conspicuous feature
is the relatively large development of the haustorial surface as
m
5. Diseases in which the live epidermal cells only are directly
parasitized. These may be called cases of epidermitis, for example,
diseases due to the Erysiphales (exclusive of Phyllactinia), Meliola.
6. Diseases in which the parasite grows between the living
host cells. Haustoria may be present, but if so they are not
prominent, and the apparently dominant part of the absorptive
system is the intercellular mycelium. This may be called inter-
exam
Ceph
7. Diseases in which the host tissue is displaced or replaced by
fungous masses. This may be called mvcosclerosis; for example,
'•P
which may be called tumor.
tumefi
y
306 BOTAXICAL GAZETTE [april
9. Diseases in
ma\
cells before they are actually invaded by the parasite. To these
may be applied the term necrosis. Subdivision
the basis of the part involved, as:
ga. Cortical necrosis , in which the cortex chiefly is involved; for
example, cankers caused by Sphaeropsis, B. amylovorus, and
End ot hi a.
gb. Parenchymal necrosis, in which chiefly the parenchyma is
affected, including the greater number of the soft rots; for example,
soft rots caused by B. carotovorus, Rhizopus, Penicillium, Phythia-
cysitis, Rhizoclonia, Pythium, Phytophthora, Sclerotinia, Botrytis y
C olletotrichum , and Gleosporium.
gc. Macular necrosis, in which necrosis is limited to spots,
chiefly occurring on leaves. This is divided into (1) macular
necrosis with abscission (the "sho thole" diseases caused, for
example, by Cylindrosporium and Marssonia); (2) macular
necrosis without abscission (chiefly the leaf spots, caused, for
example, by Pseudopeziza, Entomosporium, Macros porium, Lophio-
derma , Gidgnardia [Phyllosticta], Ascochyta, Ramularia, Septoria,
Diplodia, Cercospora, Colletotrichum, Gleosporium, Fusicladium,
Cladosporium, and Alternaria.
The following synopsis may make these categories and their
interrelations clear.
I. The parasite living in the sap or in cavities or parts devoid
of living protoplasm: (1) embolism; (2) wood rots.
II. The parasite for the major part of its life drawing its
nutriment from host cells that are still living: (3) endocellular
parasitism; (4) endocellular haustorial parasitism; (5) epidermitis;
(6) intercellular mycosis; (7) myosclerosis; (8) tumor.
III. The parasite living within host cells or tissues which have \
recently been killed or partially disorganized by it: (9) necrosis;
(9a) cortical necrosis; (gb) parenchymal necrosis; (gc) macular
necrosis; (gc f ) macular necrosis with abscission; (gc") macular
necrosis without abscission.
There is an apparent omission of hypertrophy and hyperplasia,
but I regard these two manifestations as symptoms rather than
as definite diseases.
University of Illinois
r
FLOWERS AND INSECTS. XX
EVOLUTION OF ENTOMOPHILOUS FLOWERS
Charles Robertson
In his Fertilisation of flowers (pp. 594, 595) Muller arrives at the
following conclusions with regard to the development of flowers:
The transition from wind fertilization to insect fertilization, and the first
traces of adaptation to insects, could only be due to the influence of quite
short-lipped insects with feebly developed color-sense. The most primitive
flowers are therefore for the most part (except, for instance, Salix) simple,
widely open, regular, devoid of honey or with their honey unconcealed and
easily accessible, and white or yellow in color (for example, most Umbelliferae
and Alsineae, many Ranunculaceae and Rosaceae) .
Gradually, from the miscellaneous lot of flower-visiting insects, all much
alike in their tastes, there arose others more skilful and intelligent, with longer
tongues and acuter color-sense; and they gradually caused the production of
flowers with more varied colors, honey invisible to or beyond the reach of the less
intelligent short-tongued guests, and various contrivances for lodging, pro-
tecting, and pointing out the honey.
The Ichneumonidae at first surpassed all other visitors in observation and
discernment, and they were thus able to produce inconspicuous flowers which
escaped the notice of other visitors. On the appearance of sand wasps and
bees these inconspicuous flowers were banished by competition to the less
frequented localities (for example, Lister a to shady woods).
The sand wasps (Sphegidae) apparently took the place to a great extent of
the ichneumons, and produced flowers where organs had to be thrust apart
(Papilionaceae) , or where a narrow cavity had to be entered (Labiatae), or
where some other action similar to the act of digging had to be performed.
Subsequently bees seem to have entered on joint possession of most of these
flowers, and to have added special adaptations of their own.
The true wasps (Vespidae) could establish themselves by the fear of their
sting (and of their jaws) in sole possession of certain flowers with wide open
mouths and abundant honey. These they developed further in relation to
their wants (Scrophtdari-a, Symphoricarpos, Epipactis latijolia, Lonicera alpi-
gena) ; but where wasps are scarce the flowers are utilized by other insects.
Bees (Apidae), as the most skilful and diligent visitors, have played the
chief part in the evolution of flowers; we owe to them the most numerous,
most varied, and most specialized forms.
307]
[Botanical Gazette, vol. 63
^o8 BOTANICAL GAZETTE [april
o
I
Whether the primitive flowers were pollinated by wind or by
insects is uncertain. The forms of flowers w r hich preceded the
angiosperms were probably entomophilous. The carpels closed
over the ovules to form an ovary and the stigma was developed
to receive the pollen. The stigma and closed ovary are regarded as
entomophilous characters and as having been developed after the
visits of insects w r ere established. The origin and development of
entomophilous flowers, no doubt, were connected with the origin and
specialization of the bees, Hymenoptera w r hich adopted the habit of
provisioning their nests with nectar and pollen. Along w r ith the
acquisition of this habit, the bees developed a coat of feathery
hairs to which the pollen might cling, these hairs on certain parts of
their bodies, as the hind legs and the ventral surface of the abdomen,
being greatly modified to form a special pollen-carrying apparatus.
Thus the pollen became absolutely essential in the economy of the
bees. To the flowers, on the other hand, the bees became impor-
tant visitors, because they had to resort to flowers frequently and
because they were provided with a coat specially fitted to retain the
pollen, and at the same time exerted themselves to get the coat as
full of pollen as possible.
Bees, as we know them, visit flowers both for nectar and for
pollen, but it is possible that the primitive bees visited flowers
only for pollen and that the secretion of nectar came after.
The view has been expressed 1 that the ordinary short-tongued
bees can collect only viscid pollen, and that therefore they could
have begun to use pollen to provision their nests only after pollen
had become sticky in adaptation to insect pollination. Specie
of Chloralictus collect the dry pollen of grasses and of Plantago,
however, and ordinary bees collect from a considerable number of
flowers pollen which is so dry that it pours out as soon as it is
released from the anthers. So bees may have commenced to col-
lect pollen when only dry pollen existed. The fact that bees are
the most highly specialized of Hymenoptera, and the latest devel-
oped, does not prove, and does not seem to establish a reasonable
presumption, that any considerable evolution of entomophilous
flowers preceded their advent.
1 Robertson, Charles, Flowers and insects. XIX. Bot. Gaz. 28:39. 1899-
1917]
ROBERTSON— FLOWERS AND INSECTS
309
Putting speculation aside,
'iect will be limited to the s
the further consideration of this
and the behavior of the insects which we know. Social flowers are
those which are so closely approximated that the visitors may
readily pass from one to another without taking wing or climbing.
They are usually found in heads, spikes, or close umbels. The
simplest flowers which we know are non-social flowers of class AB,
flowers with partly concealed nectar. Insect visits to them
show :
Class AB . .
Visits
Individuals
Species
41
o
Bees
56.8
43-7
70.2
Diptera
31.2
32.8
20.4
Other
Hymen
optera
4 7
19 5
8.0
Lepidop-
4.8
2.7
0.7
Coleoptera
Hemip-
tera
2-3
I . 2
o-5
Total
866
405
H38
These are evidently bee flowers, although they are not exclu-
sively visited by bees. No insects except bees prefer flowers of this
kind. There are no non-social flowers of class AB which are
adapted to miscellaneous insects or to particular kinds of visitors
except bees. On 14 species of class AB bees showed 43. 7 per cent
*
of the visits and 70. 2 per cent of the individuals. Of course it is
possible that the primitive non-social flowers of class AB were
visited by a miscellaneous set of the least specialized anthophilous
insects. If so, the short-tongued bees must have tended early to
monopolize them, while the other insects paid more attention to the
forms which became social.
Observations of 221 visits to 17 non-social flowers of class A,
flowers with exposed nectar, show: bees 33.4, Diptera 45.7, other
men
14.4, Coleoptera
Hemiptera 6.3. Here the
Diptera predominate, and the group is rather miscellaneous.
Some of the group are distinct fly-flowers (Asimina triloba); some
im). The
are quite simple {Asimina, M\
lophyll
dark color and pendulous position of Asimina are hardly typical.
Caulopkyll
None of
these are simple like ordinary non-social flowers of class AB.
Most non-social A have epigvnous nectaries {Hypoxis, Circaea,
»
3 l °
BOTANICAL GAZETTE
[APRIL
Galium). A characteristic flower is Circaea lutetiana
tors are:
Its visi-
Bees
Diptera
JTotal
Species
8l.8
94
18. 1
5-9
II
Individuals
84
*" m ¥
\
Class A is a poor place to look for simple flowers. The majority
are social and have epigynous nectaries, both forms of specialization.
Except class J?, 1 this class is the only one in w r hich the majority of
the species are social. The visits to 23 social A are as follows : bees
21.9, Diptera 38.3, other Hymenoptera 27. 3, Lepidoptera 2.6,
Coleoptera and Hemiptera 9.6, making a total of 2335.
Table I, based on 10,041 visits, shows the percentages of visits
of all classes to flowers adapted to short-tongued insects, usually
small flowers with nectar exposed, partly or wholly concealed, but
never deep seated.
TABLE I
Bees
Diptera
Lepidop-
tera
Coleoptera « Hemiptera
Lower
Hymen
optera
Percentage of visits
To non-social flowers
To social flowers . . . .
18. 1
41.8
12.4
735
11. 2
34-8
8.6
833
6.1
787
4 .1
84.9
Percentage of total visits
To non-social flowers
To social flowers
59
31
o
25-3
33-^
7.2
50
2.0
4.4
0.3
1.0
5-3
24 -4
Of the visits of bees, 18 . 1 per cent are to non-social small flowers,
and these form 59 . 5 per cent of the total insect visits to such flowers.
Sixteen non-social small flowers, on which the individual insects
were taken as they came and counted, showed 335 visits and 1520
individuals. The percentage of bee visits was 59.1, but of bee
individuals 74.2, showing that bees are more important than the
percentage of visits indicates.
!9i7]
ROBERTSON—FLOWERS AND INSECTS
3"
The relations of bees and other insects to non-social and social
flowers in general (based upon 13,942 visits of 1287 insects to 437
flowers) are shown in table II.
TABLE II
Lower
Hymen-
optera
Hemip-
tera
Coleop-
tera
Diptera
Lepid-
optera
Bees
All
Except
Bees
Total
Percentage of visits
To non-social flowers
To social flowers
44
95-5
6.1
93-S
9-3
90.6
13.6
86. 3
22.6
773
32.1
67.8
11. 9
88. o
20.7
79.2
Percentage of total visits
To non-social flowers
To social flowers . . . .
3-6
20.4
O. 2
O.9
14
3-5
17.8
29.4
9 3
8-3
67.4
37-2
32.5
62.7
99 9
99-9
Of the total visits of bees, 32.1 per cent are to non-social
flowers, and these form 67.4 per cent of the total insect visits to
such flowers. Of the total visits of other insects to non-social
flowers, the percentage is 4 . 4 for lower Hymenoptera, 6.1 for
Hemiptera, 9.3 for Coleoptera, 13.6 for Diptera, and 22.6 for
Lepidoptera; or a general percentage of n. 9. Since bees make
over
luptcict, UI ct gCllCIctl pCIXeilLctgC Ul ll.y. om^t; uccs maivv,
two-thirds of the insect visits to non-social flowers, it is evi-
1 * t i * • r% 9 1 * 1 1 ••• /•
instrumental
such flowers.
Of the total visits of bees, 67.8 per cent are to social flowers,
so that bees show a strong preference for these flowers also, although
not as strong a preference as the Lepidoptera with 77.3, the Dip-
tera with 86.3, the Coleoptera with 90.6, the Hemiptera with
93 . 8, and the lower Hymenoptera with 95 . 5 per cent.
One might suppose, with Muller, that the non-aculeate
Hymenoptera have had an influence in the development of some
primitive flowers, and that these flowers were further modified by
the aculeate Hymenoptera, and finally became highly specialized
in connection with the development and specialization of the bees.
When, however, we look for such flowers, we find only the so-called
ichneumon flowers, Lister a ovata and Chamaerarchis alpina, belong-
ing to the most highly specialized of monocotyledons. In the
312
BOTANICAL GAZETTE
[APRIL
case of the Ichneumonidae only 2 . 5 per cent of the visits are to
non-social flowers.
The only flowers supposed to have been modified by the Vespi-
dae are the so-called wasp flowers, Epi partis latifolia (Orchidaceae)
group of non-social
belonging to the most highly specialized
monocotyledons, Scrophularia nodosa (Scrophulariaceae) belonging
to a distinctly melittophilous family, Lonicera alpigena belong-
ing to a melittophilous genus, and Symphoricarpos racemosus
belonging to the epigynous Caprifoliaceae. None of these belong
to primitive forms of flowers which might have preceded the
advent of the bees. Only 8 . 7 per cent of the visits of Vespidae
are to non-social flowers.
With the exception of Symphoricarpos, all of the flowers men-
tioned by Muller as having been modified in adaptation to the
lower Hymenoptera are zygomorphous : Orchidaceae, Papilionaceae,
Labiatae, Scrophularia, and Lonicera alpigena. Zygomorphous
flowers, except such forms as Aristolochia, with siphonate zygo-
morphy, and the outer flowers of the umbels of Heracleum, with
radiate zygomorphy, are typically non-social and adapted to bees
which visit each flower separately. They have a landing either
above or below the stamens and pistils and usually dust the visitor
on the lower or upper side. It is fairly inconceivable that zygo-
morphy should have originated in crowded inflorescences where
the flowers might be approached from any side. Excluding such
flowers as Heracleum, Aristolochia; Amorpha, Petalostemon, and
Melilotus in Papilionaceae ; and Pycnanthemum, Lycopas, and
Mentha in Labiatae, 100 zygomorphous flowers show: bees 74-3*
Diptera 8.5, other Hymenoptera 9.1, Lepidoptera 7.1, Coleoptera
and Hemiptera 0.7, making a total of 1 1 1 7 visits.
Visits to the Papilionaceae show:
'
Non-social (24) . .
Social (9)
Total (33)
Amorpha, etc. (4)
Bees
Diptera
Other
Hymen-
optera
Lepidop-
tera
Coleop-
tera. He-
miptera
-
975
1.6
0.8
O.O
O.O
56.1
16.3
23.0
*5
2.9
65.0
1 S 1
18.2
1.2
2.2
45 3
18.5
29.4
2-3
43
Total
123
447
570
3° 2
-
I
1917]
ROBERTSON— FLOWERS AND INSECTS
313
When the lower Hymenoptera together make only o . 8 per cent
of the visits to the non-social Papilionaceae, it is evident that they
have had little to do with the evolution of the Papilionaceae, even if
they were instrumental in their origin. To support the latter con-
dition it would be necessary to show that the non-social forms were
developed from the social forms.
Visits to Labiatae show:
Non-social (13) .
Social (12)
Total (25)
Lycopus, etc. (5)
Bees
Diptera
Other
Hymen-
optera
Lepidop-
tera
Coleop-
tera,
Hemiptera
831
395
44.6
29.6
5-8
20.8
19.0
24.6
0.8
24.6
21.8
34- S
IO. O
12.7
12.4
7.8
O.O
2.2
1-9
3-2
Total
119
897
1016
576
When the lower Hymenoptera show 24.6 per cent of the visits
to social Labiatae and only 0.8 per cent to non-social Labiatae,
it is hard to connect them with the origin of the Labiatae unless we
suppose that the non-social developed from the social. Muller
(Fertilisation of flowers, p. 471) says: "Delpino considers Mentha
and Coleus degraded forms of the labiate type; he, however, gives
no reason for thinking them to be such, and not rather less special-
ized forms, differing less from the common ancestors of the Labia-
tae/' If there are non-social zygomorphous wasp flowers or
ichneumon flowers, no doubt they should be regarded as modified
from bee flowers.
The view held here, that the early flowers were non-social and
modified in connection with the visits of bees, and
flow
ers in
linly visited by other insects are later, is supported
by what is known of the behavior of insects and by inferences from
the affinities of the flowers. Of course, if it can be shown that the
primitive flowers were social and that the non-social flowers were
developed from them, this view will have to be abandoned for
that of Muller.
Of the total visits of the lower insects, 88.0 per cent are to social
flowers, and of the total insect visits to social flowers the lower
insects make 62.7 per cent. Xow the flowers which these insects
3H
BOTANICAL GAZETTE
[APRIL
prefer are not the simple ones, but the majority are social and
have epigynous nectaries.
The original or normal bees are poly lee tic. They have a
general relation to the flora and more special relations to certain
flower classes.
From these have originated the oligolectic bees and
inquilines. The oligoleges collect pollen exclusively from flowers
belonging to particular natural groups. They do not prefer flower
classes except in so far as their particular flowers happen to belong
to those classes. The inquiline bees live in the nests and at the
expense of the other bees. They get only nectar from the flowers
which happen to be the most convenient and easiest for them to
visit. The importance to the flora of these 3 sets of bees is partly
indicated in table III.
TABLE III
In a considerable number of polyleges the flight of the males
is quite different from that of the females. The males do not
make half as many visits as the females, and the flowers which they
visit are so different that their visits to flowers should be considered
separately. Table IV shows the differences.
TABLE IV
Females (£ excluded)
Males
Number
Visits
Average
Number
Visits
Average
Large polyleges
So
72
1239
2098
24.6
29.1
5°
64
114
806
722
16. 1
Small polyleges
II. 2
■"■'
Total
122
3337
273
1528
133
1
groups of visitors preferring certain
flowers are separated as shown in table V. Usually large flowers
)
1917]
ROBERTSON— FLOWERS AND INSECTS
315
Ma
Mi
forms
TABLE V
E#
Flora
Small bees, polyleges $ . . .
Large bees, polyleges 9 . . .
Sphingidae
Humming-bird (Trochilus)
N ON -SOCIAL
Social
Ma
Mi
Total
Ma
Mi
Pol
Total
30.2
24.2 54.4
18.7
21-5
5-2
45-5
5.0
3°-4
355
n. 7
43-6
9.0
64.4
359
13-4
49-4
3° 9
15.8
3-7
5° -.5
54. 5
0.0
54-5
40.9
45
0.0
45-4
82.7
3-4
1
62.2
137
0.0
0.0
13.7
TOTAL
437
2098
1239
22
29
The females of the short- tongued polylectic bees form
group of insects preferring non-social Mi. They are cred
the
origin
of such flowers. The females of the
ted with
tongued
r groups
Ma. This is the largest flower class, originally
modified by long-tongued
The Sphingidae and Trochilus
in some
them.
become
order shown in table VI.
TABLE VI
Groups of insects
Large bees, polyleges S
Lepidoptera (ex. Sphingidae).
Large bees, inquilines
Small bees, polyleges S
Prosopis
Diptera
Large bees, oligoleges
Small bees, inquilines 2
Small bees, oligoleges
Coleoptera
Hemiptera
Lower Hymenoptera
Small bees, inquilines 6
Social
62.1
77-9
79-3
80.4
86.1
86.3
86.5
872
88.6
90.6
93-8
95 5
96.0
Some female bees on their pollen vi
social flowers. Eighty-five species of
tongued bees, with
316 BOTANICAL GAZETTE [april
806 pollen visits, and 1155 nectar visits of females and workers,
show the following percentages of visits to social flowers with
exposed pollen: for nectar 41 . 1 ; for pollen 49. 2. Compared with
the visits of the females for nectar, the females when collecting
pollen make 8. 1 per cent more visits to social flowers.
There are some large social inflorescences composed of flowers
with exposed or only slightly concealed nectar. Long-tongued
bees practically avoid them on their nectar visits, but often visit
them for pollen. Such are Comus, Hydrangea, and Viburnum.
Vitis, with exposed nectar, seems to be an important source of
pollen for female bumblebees. The aggregation of flowers in social
clusters has been interpreted as an adaptation for gitonogamy,
but it occurs about as often in cases where gitonogamy is impossible.
Finally, the evolution of entomophilous flowers is held to have
proceeded in the following manner. The primitive flowers were
non-social flowers of class AB, with partly concealed nectar,
adapted to short- tongued bees. These have produced flowers with
exposed nectar more favorable to flies, and flowers with more
concealed nectar still more favorable to bees. A few have become
adapted to flesh flies (Asimina), and others to minute flies (Aristo-
lochia) .
The non-social small bee flowers have produced social forms still
favoring small bees., but admitting other short-tongued insects.
These finally pass into the extreme social forms which have become
modified to suit miscellaneous short-tongued insects.
The non-social small bee flowers have been modified further
and developed into non-social long-tongued bee flowers. Some of
these have been appropriated by birds and others by Sphingidae,
and perhaps still others by butterflies.
The non-social long-tongued bee flowers have also been modified
into social forms attracting Lepidoptera and long-tongued Diptera.
These are still considered as bee flowers, but some of them may more
properly be regarded as adapted to miscellaneous long-tongued
insects. The social long-tongued bee flowers also pass into social
short-tongued bee flowers, and finally into social flowers adapted to
miscellaneous short-tongued insects.
Carlixville, III*
m
DOES THE TEMPERATURE COEFFICIENT OF PERME-
ABILITY INDICATE THAT IT IS CHEMICAL
IN NATURE ?
W, J. V. OSTERHOUT
In a recent paper Stiles and Jorgensen 1 state that the absorp-
tion of hydrogen ions by tissues of the potato has the temperature
coefficient of a chemical reaction (2.18-2.22). They apparently
reach the* conclusion that "the substance with which the acid
19 :~ a.
reacts is presumably the plasma membrane or some part of it,"
and that the facts suggest the view "held by Pauli and Sztics, who
regard the entrance of ions into the cell as due to the reversibility
1
of such a reaction between ions and the plasma membrane."
These statements, together with the title of their paper, "The
effect of temperature on the permeability of plant cells to the
hydrogen ion," indicate that they regard the temperature coefficient
found by them as the temperature coefficient of permeability to
hydrogen ions.
*
This view, if well founded, is of considerable interest, as it
ndicates that permeability is chemical 2 rather than physical in
nature, since (unless vapor tension is a determining factor) no
physical processes are apt to be involved in this case which have a
temperature coefficient as high as 2. 3 In view of this the state-
ments of Stiles and Jorgensen deserve careful examination.
It should be noted that the only criterion of permeability
employed by them was absorption from a solution. Their method
consisted in placing slices of potato in a solution of HC1 and
'Ann. Botany 29:611. 1915.
'Browx and Worley (Proc. Roy. Soc. London B. 85:546. 1912) have shown
that the temperature coefficient of absorption of water by seeds is 2, but it is not
clear whether this applies to imbibition (or other processes) taking place inside the
cells, or to the permeability of the protoplasm. If it is really the coefficient of per-
meability to water, it is by no means necessary to extend this conception to permea-
bility to substances other than water.
3 Cf. Kaxitz, A., Temperatur und Lebensvorgange. Berlin, 19 15 (p. 165).
I
317I (Botanical Gazette, vol. 63
318 BOTANICAL GAZETTE [april
determining the loss of hydrogen ions from the solution by means
of a hydrogen electrode.
It may be observed in this connection that the absorption oi
dissolved substances by living cells has been employed extensively
as a criterion of permeability. The amount of absorption is
usually determined by analysis (of the solution or of the tissue)
before and after the organism is placed in the solution. A more
convenient method, which suffices in some cases, is to determine
the conductivity of the solution. Nephelometry is also useful.
Such methods may also be used to determine the excretion of sub-
stances by the organism.
The results obtained by these methods have been so largely
misinterpreted that there is widespread confusion in regard to their
significance. This confusion is due in part to uncritical technique
and in part to overlooking some of the many variables involved in
such experiments; but the principal difficulty lies in confusing
permeability with absorption.
The nature of this difficulty is evident from the following
illustration. Suppose a glass tube closed at one end by a membrane
in contact with a solution to which it is freely permeable. The
solution will pass through the membrane into the tube until
equilibrium is established. If, however, we place in the tube
something which precipitates the dissolved substance, more of the
latter will diffuse in, and this will go on as long as the precipitation
continues. It is not even necessary that the precipitation should
occur, since the result can be obtained by causing the dissolved
substance to unite with something within the tube so as to form a
compound which cannot pass out through the membrane. 4 The
dissolved substance will then continue to pass into the tube.
It is evident that the permeability of the membrane remains
the same whether precipitation or other chemical action occurs or
not. But while the permeability remains the same, the amount of
adsorption will vary enormously.
This may be observed with the living cell. When a cell is
placed in a dye which is precipitated within the cell (giving a
visible precipitate), the absorption of the dye goes on as long as
4 Cf. Loeb, J., Dynamics of living matter. 1906 (p. 72).
1917] OSTERHOUT— PERMEABILITY 319
6
the precipitate continues to form, while in the case of a dye which
is not precipitated (and which does not form a compound incap-
able of passing out), the absorption ceases as soon as the concen-
tration within the cell equals that of the solution.
It is evident, therefore, that the temperature coefficient observed
by Stiles and Jorgensen may be that of a chemical process 5
involving the union of hydrogen ions with some constituent of the
cell other than the plasma membrane (or other surface), in which
case it would have no bearing upon the problem of the nature of
permeability.
Some time ago the writer sought to throw some light on this
problem in ascertaining the temperature coefficient of permeability
by a method which is free from the objections just discussed. By
this method 7 the electrical conductivity of living tissue was deter-
mined in such a way that it may be regarded as a measure of the
permeability of the protoplasm.
In these experiments a series of disks of Laminaria were packed
together (like a roll of coins) so as to form a solid cylinder about 2
inches in length. The electrical conductivity was then measured
at various temperatures. The temperature coefficient obtained in
in this way was 1 . 33. The tissue was subsequently killed, whereby
the conductivity was increased to practically that of sea water.
The temperature coefficient of the dead tissue proved to be 1 . 26,
which is practically the same as that of sea water.
If most of the resistance were due to apparatus, cell walls
(intercellular substance), and sea water, and these had low tem-
perature coefficients (for example, 1 . 26), that part of the resistance
which is due to living protoplasm might have a high temperature
coefficient (for example, 2) without much raising the temperature
coefficient of the total resistance. The resistance of the apparatus
(and the sea water contained in it) was determined at each tem-
perature and subtracted from the total (giving what is called the
5 Absorption may also play a part in this connection.
6 Cf. Biochem. Zeitschr. 67:272. 1914.
7 Even if the hydrogen ion unites "with the plasma membrane or some part of
it," the temperature coefficient of this process would not necessarily be the temperature
coefficient of permeability.
320
BOTANICAL GAZETTE
[APRIL
i
net resistance), so that we need consider only the resistance of the
protoplasm, of the cell walls imbibed with sea water, and of the
capillary films of sea water between the disks.
When the net resistance is 1200 ohms, we find that on killing
the tissue the resistance drops to about 100 ohms. Since this
represents the resistance of the cell walls and of the sea water
plus the resistance of the dead protoplasm, it is evident that the
resistance of the cell walls and of the sea water together must be
less than 100 ohms. So far as can be judged from microscopic
measurements, the fraction of the cross-section of the conducting
column occupied by the cell walls is less than half, and it is prob-
able that when the net resistance is 1000 ohms, not more than 50
* *
ohms are due to cell walls and to the sea water adhering to the
tissues.
It is evident, therefore, that if the resistance of the living
protoplasm had a temperature coefficient of 2, the temperature
coefficient of the total resistance would be only a little less than 2.
We may conclude, therefore, that the temperature coefficient of
permeability is not far above 1.33. This indicates that permea-
bility is not chemical in nature, although it is not absolute proof,
as some chemical reactions have low temperature coefficients.
It would seem, therefore, that we cannot accept the idea that
permeability is chemical in nature without much more conclusive
evidence than we possess at present.
Laboratory of Plant Physiology
Harvard University
8
8 The problem is complicated by the arrangement of the protoplasmic masses
BRIEFER ARTICLES
A METHOD FOR PRODUCING CONDUCTIVITY WATER
SUITABLE FOR WATER CULTURE EXPERIMENTS 1
(with one figure)
An examination of one of the most recent types of water stills has
convinced the author that there is abundant opportunity for the presence
of copper and other metals in the distillate. The boiler is made of
copper, not completely covered by tin; consequently, a coating of cop-
per carbonate forms which may be conducted over in the spray during
rapid distillation. Although the condenser itself may be of block tin,
there is ample opportunity for contact of the distillate with brass con-
nections.
On account of the reputed great physiological activity of copper, it
was deemed advisable to use water free from the suspicion of contami-
nation. This led the author to devise a method for producing water of
high resistance in sufficiently large quantity for water culture experi-
ments. The apparatus here described has been used for some time and
has been found entirely satisfactory.
The level of water in a tubulatured retort is regulated automatically
by a siphon (i) which discharges to a constant level in receiver (3). The
end of the water tube (2) of the regulator is so adjusted that air can rise
into the reservoir above only when the level in the retort is lowered
slightly by distillation. Then the vacuum pressure is relieved slightly
so as to allow water to flow into the siphon.
It was found necessary to provide the water seal siphon with an
upright tube to prevent the stoppage of the siphon by gases expelled
from the water when heated.
the
cr
minimize
— *— / J*
being carried over. A pledget of glass wool is placed in the bent neck
of the retort to remove spray and return it to the retort. Condensation
of the distillate is affected by a glass water jacket fitted to the neck of
the retort by rubber stoppers.
1 Published by permission of the Secretary of Agriculture.
3 21
■1
322
BOTANICAL GAZETTE
[APRIL
The system can be isolated almost entirely from the atmosphere by
the protecting tubes and the water seals as shown in the diagram. The
principal advantages of the apparatus are that it requires little attention
I. Feeding Siphon.
2. Tube to adjust *ater level in 3
3. Constant level.
4. Retort with neck bent at 1 35°
5. Water seal.
6. Pledget of glass wool.
7. Condenser.
8. Adapter making water seal
connection .
9. Electric Flask Heater.
10. Rubber connection.
I I. Rubber stopper.
~
Fig. i
-
beyond occasional cleaning, and can be relied upon to produce a constant
supply of high resistance water containing only materials dissolved from
% • m - m ■ m m m m
slightly soluble glass.
culture, Washington, D.C.
>/
CURRENT LITERATURE
BOOK REVIEWS
Two new college texts
The two recent texts by Ganong and Gager agree in the modern spirit
evident in each, but they differ distinctly in the selection and arrangement of
material. In Ganong's text 1 the arrangement of topics is primarily mor-
phological. This arrangement will undoubtedly prove here, as it has in many
an earlier text, its peculiar fitness for an introductory textbook, because of
simplicity and its ready intelligibility to the beginner, who already knows the
primary organs of the plant by sight and by name. In the 6 chapters of the
body of the book the discussion in succession of leaf, stem, root, flower, fruit,
and seed is carried out in each case with that close interrelating of structure
function
intimate
organization. Each of these chapters includes a section on the economics and
cultivation of the structure under consideration. The chapter on the flower
contains concise but clear discussions of the significance of sex, of heredity, of
evolution, and of plant breeding, while the following chapter has a brief section
on plant diseases. Ecology and paleobotany are not discussed in this part.
The 274 illustrations include a considerable number of original ones, of
which figs. 85 and 162 are excellent examples, and there are many less frequently
copied ones from various standard works. It is not clear to the reviewer,
however, that such synthetic diagrams as those of the leaf, stem, and root
(figs. 11, 105, 166) are really needed by the average student. They do sug-
gest, it is true, certain more important features of the structure and work of
each organ, but because of the omission, for the sake of simplicity, of some other
essential structures they are liable to be misleading. Properly selected,
accurate drawings would avoid this objection and still be entirely intelligible.
The reviewer is inclined to question also whether the substitution of drawings
of models showing leaf arrangement, for figures of the stems and leaves them-
selves, is really necessary as an aid to the imagination of the ordinary college
student. The second part, entitled "The kinds and relationships of plants,"
is expected to be ready during 191 7.
1 GANONG, William F., A textbook of botany for colleges. Part I. The structures
and function- of plants. 8vo. pp. xi+401. New York: Macmillan. 19x6.
3 2 3
324 BOTANICAL GAZETTE . [april
Gager's text 2 is evidently intended, like Ganong's, as a guide for an
introductory, cultural course for college students, which shall at the same time
serve as a foundational one for students who are to pursue the subject further.
The arrangement of topics, however, differs in being professedly physiological,
at least in Part II, which corresponds most nearly to the body of GANONG's
book. Part I ("Introduction") deals with the organs of the cormophyte and
the structure of the cell. Part II ("The vegetative functions of plants'")
includes chapters on the loss of water, absorption of water, the path of liquids
in the plant, nutrition, fermentation, respiration, growth, and adjustment to
surroundings.
Chapter IV, under the title "Loss of water," which does not very ade-
quately forewarn the reader of the nature of its contents, discusses some of the
essential facts of the gross morphology, histology, and physiology of the leaf.
Chapter V ("Absorption of water") treats of the absorptive function of the
soil root, but other functions and the structure of the root, aside from that of
the root hairs, are not considered here, nor could anything but the briefest
mention of them be found elsewhere in the book. Certain important features
of the structure and activity of the stem also are either not referred to at all,
or are barely mentioned. Thus, such tissues as bark, phellogen, cork, sieve
tubes, etc., are not mentioned in the index, or more than incidentally referred
to in the text. Secondary thickening, types of branching, the various habits
assumed by the stem, the structure of buds, etc., are not given space for any
real discussion or explanation. These omissions are apparently part of the
plan of the book and are interesting as showing the author's estimate of the
relative importance of these topics among the large number from which
selection must be made.
The 26 chapters of Part III ("Structure and life histories") include dis-
cussions of the life histories of a considerable number of types, especially of the
mosses, ferns, and flowering plants. The fern is made the primary type in
these discussions of life cycles, and the whole series is rather copiously illus-
trated. Important and interestingly written chapters in this part are those
dealing with the problem of sex in plants, the economic importance of fungi,
• evolution, Darwinism, experimental evolution, heredity, and paleobotany.
The treatment of these themes, with the series of accompanying portraits of
some of the great naturalists, serves to suggest something of the history of
certain important botanical theories.
The book is abundantly illustrated with 434 figures, a good share of which
are original drawings or halftones. While the appearance, for example, of such
illustrations as figs. 127, 198, 263, and 286 is to be welcomed, the same cannot
justly be said of some others. The use of such illustrations as figs. 37, i4 2 >
151, 160, 165, or 180 would seem scarcely justified on grounds of mere novelty,
2 Gager, C. Stuart, Fundamentals of botany. 8vo. pp. xvi+640. Phila-
delphia: Blakiston's Sons. 19 16.
f
191 7] CURRENT LITERATURE 325
when much clearer ones of the same objects are already available.— D. S.
Johxsox.
MINOR NOTICES
North American flora. — The third part of Vol. 34 continues the presenta-
tion of Carduales by Rydberg,* including the completion of the Tageteae
and the Anthemideae. In the Tageteae 22 genera are recognized, the last
5 being presented in this part. Of these the large genera are Pedis with 71
species (11 new) and Porophyllum with 42 species (10 new). A new genus
(Hydropedis) is described, based on Pedis aquatic a Wats.
The recognized genera of Anthemideae number 21, a considerable number
of them being segregated from more familiar genera. The largest genus is
Artemisia with 120 species (29 new), followed by Achillea with 24 species
(6 new). The other genera are represented by comparatively few species.
Three new genera are described as follows: Vesicarpa, based on Artemisia
potentilloides Gray; Chamartemisia, based on Tanacetum compadum Hall;
Artemisiastrum, based on Artemisia Palmeri Gray. — J. M. C.
The theory of evolution. — Scott 4 has made an excellent restatement of
the evidences of organic evolution. The somewhat hackneyed subject is
enlivened by a forcible and very readable presentation. The book is the result
of the organization of 6 lectures (the Westbrook Lectures for 1914). In addi-
tion to the evidences from classification, comparative anatomy, embryology,
paleontology, and geographical distribution, the author presents evidence
derived from domestication, from blood tests, and from experiment.
The opening chapter gives a brief historical review of theories of evolution
and a concise statement of the present status of the question. I have seen no
better presentation of this body of data for both biologist and general reader
than that given in this little book. My only criticism is that it is insufficiently
illustrated, although the few illustrations used are well chosen — H. H. Newman.
A moss flora. — Grouts has published a very convenient list of the moss
flora of all counties of New York and New Jersey adjacent to New York City.
The moss flora of this area has probably been explored more thoroughly than
that of any other region of the United States. Numerous keys make the
recognition of genera and species relatively easy, and the excellent photographic
plates illustrate the genera. Such a publication should stimulate the study of
a very interesting flora, for, as the author remarks, "in and around New York
3 Rydberg, Per Axel, North American Flora 34-'part 3. pp. 181-288. Cardu-
ales: Carduaceae{ Tageteae, Anthemideae). New York Botanic Garden. 1916.
« Scott, \Y. B., The theory of evolution. 8vo. pp. vii+183. Xew York: Mao
millan. 1917.
s Grout, A. J., The moss flora of New York City and vicinity. 8vo. pp. 120.
pis. 12. Xew Dorp (N.Y.): published by the author. 1916.
326 BOTANICAL GAZETTE [april
City the moss flora of the north and of the south meet and mingle, and the
number of species occurring is large, varied, and interesting/' — J. M- C.
NOTES FOR STUDENTS
Transpiration studies. — Among several recent papers dealing with various
phases of the study of transpiration, a prominent place should be given to one
by LIVINGSTON and Shreve 6 upon improvements in the use of the cobalt
chloride paper method. An improved paper slip has been designed which
combines two permanent color standards and an area of carefully prepared
cobalt chloride paper. The determinations of the end points are made more
definite, therefore, and the probability of error is much reduced. An improved
device for furnishing a standard water surface is described also. The temper-
ature relations of the rate of color change in the hygrometric paper and its
permanent standardization is discussed also. These improvements will
greatly advance the method of study which has already been proved
valuable.
Another modification of methods of study is seen in Darwin's 7 investi-
gation of the relation of transpiration to relative humidity by the porometer
method, using Primus Laurocerasus and eliminating the action of stomata by
applying vaseline to the lower surface of the leaves and then placing their inter-
cellular spaces in communication with the external air by means of incisions.
Plotting the results, he found that transpiration varies directly as relative
humidity when a correction is made for the fact that the transpiration rate is
not zero in saturated air. The fact that transpiration does occur in saturated
air is due, as pointed out by Sachs, to the production of heat in the leaf by
respiration. The experiments show T ed that for the transpiration to be entirely
checked a humidity of 5 per cent above saturation would be necessary, and
hence the temperature of the leaf due to respiration is, under the conditions of
the experiments, o?8C. above that of the atmosphere.
Using similar methods and materials, Darwin 8 also studied the effect of
diffuse light upon transpiration. The results show so remarkable an amount
of variation that it seems dangerous to draw any conclusions other than that
light tends to increase the water loss for some unknown reason when its influ-
ence upon the action of stomata has been eliminated. This increase averages
about 33 per cent.
6 Livingston, B. E., and Shreve, Edith B., Improvements in the method for
determining the transpiring power of plant surfaces by hygrometric paper. Plant
World 19:257-309. 1916.
7 Darwin, F., On a method of studying transpiration. Proc. Roy. Soc. London
B 87:269-280. 19 14.
8 ^ xhe effect of light on the transpiration of leaves. Proc. Roy. Soc.
London B 87:281-299. 1914.
>
1017] CURRENT LITERATURE 327
In a more recent report by the same investigator, 9 the corrections pre-
viously indicated for humidity and light are used in experiments designed to
show the relation between the rate of transpiration and stomatal aperture, the
latter condition being determined by the use of the porometer. There was
also applied a further correction for cuticular transpiration. The final results
show many irregularities, but are regarded by Darwin as giving substantial
f support to his thesis that transpiration is regulated by stomatal aperture. He
apparently finds nothing corresponding to the incipient drying of Livingston
and Brown, or the saturation deficit of Renner, although it seems possible
to the reviewer that some of his many irregularities might require some such
explanation.
In striking contrast to this theory there comes an account of a study of
water relations of cacti. On account of their peculiar behavior, these plants
offer special advantages as well as special problems in the general study of
transpiration. Their transpiring power differs from ordinary plants in being
greater during the night than during the day. This behavior Mrs. Shreve 10
has investigated, and has found that there is a regular diurnal march of change
in the water-holding capacity of the internal tissues that seems both directly
and indirectly responsible for the changes in transpiring power; that is, the
transpiring power of the cactus is usually greater at night than during the day
because the water-holding capacity of the tissues is greater by day than by
night. The variations in water-holding capacity act upon transpiring power
indirectly by closing the stomata, which in cacti are usually closed during the
day and open at night, and they also act directly by resisting the evaporating
power of the air. It seems possible, as the author of this paper points out,
that a similar change in the tissues of non-succulents may account for the mid-
day drop in their transpiring power.
Briggs and Shantz 11 have made an extensive and detailed study of trans-
piration as related to growth and to various climatic factors. The measure-
ments were made at Akron, Colorado, during the seasons of 19 14 and 191 5
and were for 270 pots of 115 kgm. each of soil, including some 25 different crop
plants. Continuous automatic records were obtained for air temperature,
solar radiation, wet bulb depression, wind velocity, and evaporation from both
shallow and deep tanks. Among the comparisons instituted, one of the most
instructive is the correlation between transpiration for the small grains and
various physical factors. This is expressed by mean correlation coefficients,
some of which are those with evaporation from a shallow pan, 0.87; with wet
9 Darwin, F., On the relation between transpiration and stomatal aperture.
Phil. Trans. Roy. Soc. London B 207:413-437. 1916.
10 Shreve, Edith B., An analysis of the causes
power of cacti. Physiol. Researches 2:73-127. 1916.
* •
11
normal
* ** r 7 7 — — ^ *
period and its correlation with the weather. Jour. Agric. Research 7' *55~ 212 - J 9 l6 -
328 BOTANICAL GAZETTE [april
bulb depression, 0.88; with temperature, 0.71; with radiation, 0.65; and
with wind velocity, 0.22. These serve to emphasize the close relation of
transpiration to humidity and evaporation and the comparatively slight influ-
ence of wind velocity.
It is also interesting to note that during a 10-day period of maximum trans-
piration the daily loss of water ranged from 6 to 9 times the dry weight of the
crop for millets and corn, from 12 to 16 times for the small grains, and up to
36 to 56 times for alfalfas. During the same 10-day period the annual crop
plants lost about one-fourth of the total water transpired during the entire
season. The transpiration of the different crop plants per unit area of plant
surface shows less variation than the transpiration per unit of dry weight,
hence the greater efficiency shown by certain plants in the use of water
seems to be due more to a reduction in plant surface than to a reduction of
transpiration per unit area of surface. Various other comparisons make
this a valuable report for both the botanical and the agricultural
investigator.
Another investigation undertaken with a view to economic application of
results shows scientific merit of a high order and is comparable in methods and
results with that just reviewed. In it Kiesselbach 12 has limited his research
to corn grown under conditions very closely approximating those of crop pro-
duction. A portion of the experiments was devoted to the development of a
satisfactory technique, and errors of former experimenters due to the use of
immature plants and small quantities of soil were pointed out. It is impossible
to summarize the many data, but it is interesting to note the agreement with
the results of Briggs and Shaxtz in the very large proportion of total water
used by the plant, which is lost during a comparatively short period of maximum
transpiration. A rather surprising result is that it was found that corn plants
grown for 2 months in a humid greenhouse exhibited no different transpiration
rate per unit leaf area when transferred to dry conditions than took place from
plants continuously grown under dry conditions. Further it appears that
while there were considerable variations in the different varieties in regard
to thickness of leaf and epidermis, and also in number of stomata per unit of
leaf area, there was no consistent correlation between these structural features
and the transpirational rate per unit of dry matter produced. In spite of this
it was found that the water requirement of different varieties differed to a
marked degree, suggesting that drought-resistant strains may be selected. It
also developed as an important result of the investigation that water economy
is greatest with neither an excessive nor a deficient soil moisture supply, and
further that increasing fertility by the application of fertilizers resulted in
still greater water economy.
12
Kiesselbach, T. A., Transpiration as a factor in crop production. Research
/ r — l A M.
Bull. no. 7, Neb. Agric. Exp. Sta. pp. 214. pis. 4. figs. 24. 19 16.
i9!7] CURRENT LITERATURE
329
The relation of soil moisture to transpiration and to economy in the use of
water is also shown by the investigations of Yuncker, 13 who, using the wax
seal method and weighing the sealed pots, has studied the comparative rates
of transpiration of young plants of Zea Mays growing in soil with 3 differ-
I ent soil moisture contents, all somewhat above the wilting coefficient and
I showing respectively 25, 45, and 65 per cent of possible saturation. The rate
of transpiration and the water requirement for periods up to 1320 hours was
least for the driest cultures, which, however, seem to have had no deficiency in
water supply, and most for those with the highest soil moisture content. Thus
among other things it appears that the experiment demonstrated that the
amount of dry matter formed was not at all proportional to transpiration.
Geo. D. Fuller.
Taxonomic notes. — Lange, 14 in the second part of his studies on the
agarics of Denmark, has published his results with Amanita, Lepiota, and
Coprinus. The first part, published in 1914, contained a general introduction
Myc
species
■
Lepiota 31 species, 1 of which is new; and Coprinus 33 species, 3 of which are
new. The presentation of each genus is preceded by a full discussion of its
characters and an analytical key.
Macbride, 1 * in presenting "The true Mertensias of western North
America," recognizes 32 species, 4 of which are described as new. Gray's
Synoptical Flora (1886) contains 7 species, 2 of which are restricted to the
Atlantic states. Since that time, 74 species have been proposed. In a
"Revision of the genus Oreocarya" 45 species are recognized, 4 of which are
described as new. In "Notes on certain Borraginaceae," Amblyiiotopsis is
;ed
Mer
tensia, and Lit hos per mum.
Moore 16 has described 2 new genera: Capitatwpsis (Labia tae) from
Madagascar, and Megalostylis (Euphorbiaceae) from Peru or Brazil (upper
Amazon region). He also describes 13 new species from Africa.
Okamura, 1 * in his second contribution to the bryophytic flora of Japan, de-
scribes a new liverwort and 29 new species of mosses well distributed generically.
13 Yunxker, T. G., A study of the relation of soil moisture to transpiration and
photosynthesis in the corn plant. Plant World 20: 151-161. 1916.
14 Lange, Jakob E., Studies in the agarics of Denmark. Part II. Dansk. Bot.
Arkiv. 2:no. 3. pp. 53. ph. 2. 1915.
15 MacBride, J. Francis, Contrib. Gray Herb. no. 48, pp. 5 8 - I0I °-
16 Moore, Spexcer LeM., Alabastra diversa. XXVI. Jour. Botany 54:249-
257. 1916.
I7 Okamura, Shutai, Contributiones novae ad floram bryophyton Japonicam.
Pars secunda. Jour. Coll. Sci. Tokyo 38: no. 4. PP- 100. figs. 42 • *9 l6 -
330 BOTANICAL GAZETTE [april
Overholts 18 has monographed the Polyporaceae of the central states, j
including the states extending from Ohio to North Dakota and southward to (
Kentucky and Kansas. He recognizes 132 species in 7 genera, the species of
Poria and Merulius being omitted because " practically nothing is known of
them at present." The large genus is Poly par us, with 88 species; following it
are Fames with 23 species and Trametes with 10 species. The keys and con-
trasted descriptions should make the identification of species comparatively
easy. Perhaps the author is to be congratulated that he did not see fit to
propose any new species.
Smith 19 has described 10 new species and 5 new varieties of algae from the
lakes of Wisconsin, and also a new genus (Gloeocystopsis) , which combines the
external morphological characters of Gleocystis and Nephrocytium.
Stevens, 20 in a synoptical account of the species of Meliola occurring
in Porto Rico, recognizes 95 species, and describes 62 of them as new. —
J. M. C.
Sulphur nutrition. — Although sulphates have little effect on the soil flora,
and cannot function therefore as important fertilizers for all crops, the fact
that the sulphur content of most soils is rather Iqw, and that certain classes
of plants use considerable quantities of sulphur in metabolism, leads to the
possibility of sulphur deficiency becoming in certain cases a limiting factor to
crop production. Hart and Tottingham 21 have made some greenhouse \
studies on the relation of elemental sulphur and various sulphates to the nutri-
tion of certain of the Leguminosae, Cruciferae, and Gramineae, groups differ-
ing somewhat in their need of sulphur. They find that sulphates may be
beneficial to certain crops, even when functioning only as a source of sulphur.
Calcium sulphate in general gave better results than sodium sulphate. It
increased the dry weight produced by red clover 23 per cent. With rape the
greatest beneficial influence was noted when the calcium sulphate was used in
addition to a complete fertilizer. The increase due to the sulphate in this 1
case was 17 per cent. In both plants the roots were much elongated by the
sulphate, so that a much larger volume of soil is laid under contribution to the
plant, and its ability to withstand drought is much increased. The sulphate
therefore not only meets the special needs of these plants for sulphur but
improves the general physiological conditions.
ERHOLTS
Wash. Univ. Studies 3:3-98. pis. 8. 1915.
19 Smith, Gilbert Morgan, New and interesting algae from the lakes of Wis-
consin. Bull. Torr. Bot. Club 43:471-483. 1916.
20
Steven
111. Biol. Mono-
graphs 2 : 1-86. pis. 5. 1916.
21
Hart, E. B., and Tottingham, W. E., Relation of sulphur compounds to plant
!
nutrition. Jour. Agric. Research 5 : 233-249. 1915.
1917J CURRENT LITERATURE 331
The grains, barley and oats, showed little effect on the quantity of straw,
but a noticeable increase in seed production occurred on plants grown on the
soil used (Miami silt loam) .
Elemental sulphur, added as flowers, was usually toxic even in the presence
of calcium, probably because of its incomplete oxidation to sulphites. Where
bases are deficient, the toxicity may be due to accumulation of sulphuric acid
from the complete oxidation of the sulphur. — Charles A. Shull.
British Columbia forests. — Mount Robson, British Columbia, situated
at practically the present northern known limit of the continental divide, has
been visited by Cooper 22 and found to possess 2 climax forest types, one for
each of 2 climatic zones. Up to an altitude of 1000 m. the forest is of the
Pacific Coast type, with a dominance of Thuja plicata. Picea Engelmanni is
next in abundance, and is followed by Abies lasiocarpa, Tsuga heterophylla,
and Pseudotsuga mucronata. The undergrowth shows such truly mesophytic
iflora, Moneses unifl
albifl
2000
forest of Picea Engelmanni, Abies lasiocarpa, and Pinus albicaulis. In the
undergrowth Menziesia ferruginea, Cornus canadensis, and several species of
Pyrola are conspicuous. The successions upon rock surface, talus, moraine,
and shingle flat are noted, those of the two last in most detail. Upon the
moraine Dry as octopetala and Arctostaphylos rubra are followed by shrubby
species of Betula and Salix, leading to the third stage, which is the climax
forest. A similar set of stages is found upon the shingle flat, although here,
probably because of the lack of any fine soil material, the succession advances
much less rapidly than upon the moraine.
While Cooper expresses regret at the few data available for this study,
it will be welcomed as giving an insight into the vegetation of an almost
unknown region.— Geo. D. Fuller.
Large trees. — A recent contest for two prizes of $100 each, offered through
the Journal of Heredity, 2 * for photographs and data regarding the largest trees
in the United States, barring conifers, resulted in photographs of 337 trees.
The prize for the largest non-nut-bearing tree was won by a Platanus occiden-
tal near Worthington, Indiana, with a circumference, 5 ft. from the ground,
of 42 . 25 ft., and a height of about 150 ft. The largest nut-bearing tree in the
competition was a Quercus lobata on the foothills of the Sierra Nevada Moun-
tains, in San Benito County, California, with a circumference of 37 . 5 ft. and a
height of 125 ft. The largest specimens of other species were as follows:
Ulmus americana at Morgantown, West Virginia, with a circumference of 33
22 Cooper, W. S., Plant succession in the Mount Robson region, British Columbia.
Plant World 19:211-238. figs. S. 19 16.
23 Photographs of large trees. Jour. Heredity 6:407-429- M>*S-
332 BOTAXICAL GAZETTE [april
.; Qucrciis alba at Atwood, Indiana, 21 ft.; Juglans nigra at Hanover Neck,
ew Jersey, 24 ft.; and Liriodendron Tulipifera at Asheville, North Carolina,
The report of the results of the contest also contains other interesting data,
while the value of such a competition, as pointed out by Lamb, 24 consists not
only in promoting interest in the protection of tree individuals and in the con-
servation and preservation of forests, but also in affording data for the solution
of problems of distribution, of growth, and of duration. In this connection
he has prepared maps showing the distribution of 6 of the important species
represented and the location of the best specimens reported in the contest.
It is hoped that public interest in the subject will not cease with the conclusion
of the contest. — Geo. D. Fuller.
American forestry. — Recent changes and improvements have made the
magazine known as American Forestry valuable not only to the forester but also
to the botanical teacher or student interested in trees. An excellent feature
is that of devoting special attention to one particular tree species in each issue.
Well written articles are given dealing with the identification, characteristics,
and habits of the trees, and also with the lumber and its uses. During the
first half of the current year the following species have been the subjects of
special consideration: Quercus alba, Pseudotsuga Douglasii, Thuja plicata,
Betula papyrifera, Ulmus americana, and Sequoia sempervirciis. The excellence
of the illustrations in these articles is worthy of note.
There are also, in addition to the articles of more particular interest to the
professional forester, others upon more general but quite as timely topics.
Among these we may note as examples a finely illustrated article upon Cap-
ressus macrocarpa under the title of "The tree of legend and romance," in the
February issue; and several dealing with forests in time of war, showing some
of the devastating effects of the present European conflict. A recognition of
various phases of forest and country life is seen in regular departments devoted
to children, birds, ornamental and shade trees, and to wood preserving, while
quite as important are the very extensive lists of current literature. Finally,
as an indication of the international scope of its interests is a page of its notes
and news items devoted to Canadian forestry and foresters. — Geo. D. Fuller.
A vegetational map of the United States. — Shreve 25 has compiled a map
of the range of the principal types of vegetation in the United States, basing
the boundaries of the various subdivisions upon purely vegetational criteria.
The primary classes of vegetation are the well recognized ones of desert, grass-
land, and forest. Of these the first and last have been subdivided, but the
data available for the grassland are not regarded as sufficient to afford a basis
2 « Lamb, W. H., Value of the contest. Jour. Heredity 6:424-429. 1915-
2 s Shreve, F., A map of the vegetation of the United States. Geog. Rev. 3 : 1 X Q
125. 1917
1917] CURRE.XT LITERATURE . 333
for mapping. On the whole, 18 types of plant communities are recognized,
briefly characterized, and plotted. An inspection shows, as its author points
out, that the areas have in general a north and south rather than an east and
west trend, which tends to show that the major differences in vegetation are
here determined more largely by conditions of moisture than of temperature.
While the result is decidedly the best map of the sort yet produced, it is
also probable that it would be difficult to find an ecologist who would agree
with it in every particular. So much of the disagreement would be differences
of opinion as to what should be included within a single vegetational type, that
diverse criticism would be neither a gracious nor a practical task, and yet the
reviewer cannot refrain from expressing a question as to the fitness of including
both the Pinus ponder osa and P. Murray ana forests of the west and the P.
Strobus, Tsuga, and Abies balsamea forests of the east in the " northern meso-
phytic evergreen forest."— Geo. D. Fuller.
History of forest ecology,— A recent study of the historical development
of forest ecology is likely to prove of equal interest to foresters and ecologist s.
In it Boerker 26 traces the development of plant ecology from its beginnings
to the modern phase characterized chiefly by efforts to measure the various
habitat factors.
ecology
development of silviculture, dating back to the fifteenth century or even earlier;
but the founder of the science is considered to be Duhamel du Moxceau,
niddle of the eighteenth century. About a century later the work
Hartig
Wessely, Heyer, Ebermayer, Judeich
science further impetus, and resulted in the organization of a series of forest
experiment stations throughout Germany. From this beginning the advance-
ment of the science is traced to the present day, as shown in the work of
Wagner, Meyer, and Duesberg in Germany, and that of Fernow and Zox
m America. It is notable that not until 1909 were forest experiment stations
established in the United States.— Geo. D. Fuller.
Permeability
modify
(light,
1. In
some cases the stimulus decreases the permeability at low intensity and increases
it at high intensity. Koketsu 27 believes he has demonstrated that electrical
stimulation increases the permeability of epithelial cells of Tradescantia dis-
color. Cells thus stimulated are less easily plasmolyzed by ordinary plas-
molytic agents than are unstimulated cells. After recovery from the stimulus
they show a greater degree to plasmolysis by the same concentration of the
Boerker, R. H., A historical study of forest ecology; its development in the
fields of botany and foresty. Forestry Quarterly 14:380-432- J 9 l6 -
27 Koketsu, R., Uber den Einfluss der elektrischen Reizung auf die Permea-
bilitat der Pflanzenzellern. Bot. Mag. Tokyo 30:264-266. 1916.
334 BOTAXICAL GAZETTE [april
agent than do the checks. He interprets the first change as due to greater
permeability of plasmolytic agents, and the second change as due to loss of
solutes during the period of higher permeability. Sztics 28 finds that aluminum
salts render cells more difficult to plasmolyze because they harden the proto-
plasm, although they really decrease its permeability. One must look out
for a similar condition with electrical stimuli. The experiments are qualitative
but suggest the need of very careful quantitative studies. — Wm. Crocker.
Texas root rot fungus. — Duggar 29 has investigated the causal organism of
one of the most destructive of the cotton diseases, an organism which seems to
be confined largely to Texas, where the average losses have been variously
estimated to be $2,000,000 to $3,000,000. In addition to the attacks on cotton,
the fungus damages such crops as alfalfa, beans, sweet potatoes, and certain
orchard fruits. As illustrating the omnivorous habit of the fungus, Duggar
enumerates a list of nearly 30 host plants (trees, shrubs, and herbs) already
noted as used by the fungus. The chief feature of the disease is the sudden
wilting and dying of the affected individuals. The fungus was described by
Shear as Ozonium omnivorum, but Duggar concludes that it should be trans-
ferred to Phymatotrichum. In the revised description of the species the
habitat is stated as follows: "Hyphae on living roots of many plants and in the
soil; conidial stage on soil in the vicinity of diseased plants." — J. M. C.
1
Embryo and seedling of Dioscorea. — Miss Smith 30 has investigated the
embryo and seedling of Dioscorea villosa, a genus long known through the*
work of Solms-Laubach as furnishing evidence of a "second cotyledon," or
at least a seedling structure quite different from what had come to be regarded
as the monocotyl type. Miss Smith traced the development of the embryo
to the spherical 4-celled proembryo, and then followed the appearance of the
organs. She observed no cotyledonary ring, and claims that the single coty-
ledon originates as a terminal structure. It may be stated that the course of
the vascular strands suggests that the leaf called the "first secondary leaf"
occupies the position of a "second cotyledon," which would make the growing
point of the stem a terminal structure, and both cotyledons lateral. This,
however, is a matter of interpretation in connection with material. — J. M. C.
Vitality of moss protonema. — Miss Bristol 31 has discovered some remark-
able cases of the retention of vitality by the protonema of mosses. In samples
of soils obtained from various places for the purpose of ascertaining by means
28 Rev. in Bot. Gaz. 56:245. 1913.
2 « Duggar, B. ML, The Texas root rot fungus and its conidial stage. Ann. Mo.
Bot. Gard. 3:11-23. Jigs. 6. 1916.
*° Smith, Pearl ML, The development of the embryo and seedling of Dioscorea
villosa. Bull. Torr. Bot. Club 43 : 545-558. pis. 31-34. 1916.
31 Bristol, B. Muriel, On the remarkable retention of vitality of moss protonema.
New Phytol. 15:137-143. Jigs. 3. 19 16.
i9i 7] CURRENT LITERATURE 335
of cultures the algae present in the form of "resting spores/' protonema from
certain soils began to develop. In these soils the protonema had persisted in
the dried condition for 46, 48, and 49 years. A description is given of the
appearance of the cells, which seemed to be in vigorous condition. Moss spores
contain chlorophyll and are usually short-lived. "Hence the power to produce
a resting protonema filament which is able to resume growth, even after half
a century, is a great asset to the plant in preventing its extinction through
adverse climatic conditions."— J. M. C.
Anatomy of Drimys. — The genus Drimys (Magnoliaceae), belonging to
the Southern Hemisphere, is very interesting on account of the absence of
vessels. Jeffrey and Cole 32 have investigated its wound reactions from
material obtained from New Zealand and Java, and also from material at Kew.
As a result of injury, the roots develop peculiar tracheary structures, which are
regarded as a "reversionary return of vessels" because the markings of the
lateral walls resemble those found in the vessels of the Magnoliaceae. They
are clearly distinct from ordinary tracheids, but lack the perforations of normal
vessels. The authors conclude that these traumatic structures are to be inter-
preted as a clear indication of the former presence of vessels in Drimys. —
J. M. C.
A cedar swamp on Long Island, — A swamp on the southern shore of Long
Island, New York, about one mile long and half as wide, is, according to
Taylor, 33 of special interest because (1) it is probably the most northerly grove
of Chamaecyparis thy aides on the coastal plain of anything like that size; (2) the
character of the undergrowth, which includes 77 per cent of species northern
in character; and (3) it affords evidence of coastal subsidence in the transition
between the swamp and the open salt marsh and in the number of dead and
dying trees. This evidence is all the more convincing because of the remoteness
of any barrier beach or other possible regulator of exceptional tides, a possible
alternative to recent subsidence. — Geo. D. Fuller.
Flora of Isle Royale, Michigan. — Cooper 3 * has supplemented his excellent
ecological analysis of the vegetation of Isle Royale 3 * by a catalogue of its
vascular plants. As a list of the mosses of the same island was previously
EFFREY
genus Drimys. Ann. Botany 30:359-368. pL 7. 1916.
33 Taylor, Xormax, A white cedar swamp at Merrick, Long Island, and its sig-
nificance. Mem. NX Bot. Card. 6:79-88. 1916.
*< Cooper, W. S., A catalogue of the flora of Isle Royale, Lake Superior, Michigan.
Acad. Sci. Report 16:109-131. 1914.
* , The climax fore>ts of Isle Royale. Bot. Gaz. |S:*~44* "5-Ho, 189-
2 35- 1913-
336
BOTANICAL GAZETTE
[APRIL
published, 36 this catalogue advances the region to the position of having one of
the very few well known floras in the state. The present list includes 40 species
of pteridophytes and 479 species of spermatophytes. One happy improvement
in the present publication is the ecological definition of the habitat, replacing
such time-honored but meaningless phrases as "hillsides," "glades," "woods,"
and "cool dry woods." — Geo. D. Fuller.
lake
These beds in Colorado have been
finely
insects. Knowlton 37 has now published a review of the plant material on
deposit in the U.S. National Museum. Over 100 plants are presented, and
among them 18 new species are described, chiefly woody dicotyledons. Two
new genera are proposed; Palaeopotamogeton (Potamogetonaceae) and Floris-
sant ia (Solanaceae). The list of types of fossil plants from Florissant in the
U.S. National Museum includes the names of 121 species. — J. M. C.
Mushroom fairy rings. — The occurrence of well developed "fairy rings"
formed by a large mushroom known as Tricholoma praemagmim in the dry
grassland of the open mountain parks of Colorado has been described by
Ramaley. 3 * They have been observed in various localities, but all between
6000 and 9000 ft. in altitude. The rings vary much in size, the smallest
observed being 3.3 m. across, and seen to increase in diameter at a rate of
about 1 dm. per year. One of the interesting characteristics of the fungus is
its distinctly xerophytic habit. — Geo. D. Fuller.
Aerating system. — Hunter 3 * has studied the structure of various air
chambers in plants of Vicia Faba and has found spaces of various sorts in the
testa of the seed, the cotyledons, the stem, the leaves, and the root. The study
adds to our knowledge of the aerating system as developed in seed plants, even
if it rather fails to justify the author's conclusion that the system is "elabo-
rately adjusted in order to insure an efficient gaseous exchange for each living
cell no matter where its position may be in the plant tissues." — Geo. D.
Fuller.
# Cooper, W. S., A list of mosses collected upon Isle Royale, Lake Superior.
Bryologist 16:3-8. 1913.
*7 Knowltox, F. H., A review of the fossil plants in the U.S. National Museum
from the Florissant lake beds at Florissant, Colorado, with descriptions of new species
and list of type specimens. Proc. U.S. Nat. Mus. 51:241-297. pis. 12-27. 1916.
* Ramaley, Francis, Mushroom fairy rings of Tricholoma praemagnum. Tor-
reya 16:193-199. 1916.
*> Hunter, C, The aerating system of Vicia Faba. Ann. Botany 29:627-634-
19*5
VOLUME LXIII
NUMBER 5
THE
Botanical Gazette
MAY igr-j
A STUDY IN PHYSIOGRAPHIC ECOLOGY IN NORTHERN
FLORIDA
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 229
Laura Gano
tf
(with ten figures)
Introduction
Ecological investigations of the coastal plain of southeastern
United States, with few exceptions, have not been undertaken from
the standpoint of the relation of physiography to the successional
history of the plant associations, nor has the classification of this
region been satisfactorily established in comparison with other
forest formations of the United States. Schimper (ii) mapped
this portion of the coastal plain (with the exception of southern
Florida) as temperate rain forest. Sargent (io) classified it as
the southern maritime pine belt. The first classification is ob-
viously inconsistent, and the second is open to question if by pine
forest is meant a climax formation.
Except for Harshberger's detailed treatment of the coastal
plain in his Phytogeographic survey of North America, studies of this
particular region have been scattered, and usually of exceptional
localities. On the Gulf Coast, Hilgard in soil surveys in Mississippi
and Louisiana paid special attention to plants as soil indicators,
outlining associations on this basis. Studies of island plant life
in the Mississippi River sound and delta were made by Lloyd
and Tracy (8); while Mohr in his Plant life of Alabama grouped
337
338 BOTAMCAL GAZETTE [may
various plant associations belonging to the different geological
divisions of the coastal region of that state, comparing the flora in
its relationships with adjoining regions and with the West Indies
and Mexico. More recently, Harper has contributed numerous
publications containing ecological data, as the result of extensive
observations and explorations in various parts of the coastal plain, j
his most complete works being a phytogeographic study of the
Altamaha grit formation of Georgia (5), and publications in the
reports of the State Geological Survey of Florida (6, 7).
The area described in this study is included mainly in Leon
County, Florida. This county is situated half-way between the
east and west boundaries of the northern part of the state, bordering
the Georgia line and distant about 20 miles from the Gulf of Mexico.
The area is approximately 675 square miles, and as a whole is
located immediately west of the 84th meridian and between 30
and 31 north latitude.
The topography is diversified, and a soil survey (14) of this
county locates and describes 12 soil types (including meadow and
swamp) , of which the most extensive are those also common to the
coastal plain from Virginia south to Florida and west to Texas.
This section of Florida has had a varied history, dating back to
early Indian tribes and the first Spanish explorers. According to
narratives of De Soto's followers, the fame of this country as the
"land of plenty" extended to eastern and central Florida, and
made it a desirable place to seek for possession and settlement.
During the several hundred years of history chronicling invasions
and resettlement, therefore, successive clearings of the forest, from
the more fertile soils at least, must have been made. About the
time of the establishment of the capital at Tallahassee (1823) near
the center of the county, Williams (15) described " abundant
groves of oak, hickory, beech, and magnolia crowning the hills and
covering their slopes." Such early pictures are of interest now in
considering the upland forests.
Physical features
Climate. — Weather records have been kept at Tallahassee since
1885 (3). The mean summer temperature averages 79? 7, autumn
i
iQi7l GANO— ECOLOGY OF FLORIDA
339
o •.*.-. _. o
68 , winter 53 , and spring 67?6 F., indicating a moderate and
equable yearly temperature. There are records of severity, how-
ever, the lowest temperature for the state being recorded from Leon
County, — 2 F. on February 13, 1899. Frost may be expected
from November 1 until April 1, the frost record for 18 years giving
the date of the first killing frost in autumn as November 4, the
last killing frost in spring as April 6, the average date of the first
killing frost in autumn as December 5, and the average date of the
last killing frost in spring as March 3.
The mean annual precipitation for the Tallahassee station (3)
is 57.12 inches, and there are 2 marked periods of rainfall; one
(the lesser) in winter culminating in March, and the other (more
excessive) culminating in July. This summer rainfall averages
26.8 inches, and the winter rainfall 17.9 inches, the summer rains
occurring almost daily as afternoon thunderstorms, while the winter
rains are more evenly distributed between day and night. The
year is divided thus into wet and dry seasons, more or less marked,
April and November being the driest months.
There are no reliable records for relative humidity, although for
northern Florida the percentage of relative humidity is highest in
September and lowest in April.
These climatic effects combined tend to make spring (April
period) the hardest season for plants, so far as the moisture rela-
tions are concerned.
Physiography. — Limestones of the Oligocene period are con-
sidered now to be the oldest rocks of Florida and to form the rock
basis for most of the state (9). These limestones also are the sur-
face rock over much of northern Florida, and indicate the earliest
and most persistent land surface during subsequent geological
history. The presence so near the surface of readily soluble and
easily disintegrated rock has doubtless had important influence
upon the present topography and drainage, as well as upon the
character of some of the soil.
Crossing the country from north to south, the most striking
topographical feature is the division of the surface into 2 distinct
parts, a highland and a lowland. By this division about two-thirds
of the surface is included in the highland, which is a portion of the
340 BOTANICAL GAZETTE [may
narrow upland extending along the northern edge of Florida and
into Georgia, and which, on its sea-facing side, often drops abruptly
to the more recent coastal strip.
The general elevation of the upland is betweeen ioo and 200
ft. above sea level. The surface is gently rolling with series of
broadly rounded or flat topped hills, in general extending east and
west, and alternating with open, troughlike valleys. Many of the
valley streams are mere swampy or boggy tracts, or they may pur-
sue sluggish courses which end blindly, spreading out on the surface
of the ground at the lowest part and soaking gradually into the soil.
Others end in ponds which occupy basin-like depressions, or may
drain into the larger lakes and sinkholes. In this hill region the
sinkhole origin of many large lakes as well as small ponds, and the
sinkhole formation along the line of some of the valleys at present,
suggest that the depressions of this upland division may be due in
large part to subterranean erosion. At any rate, no considerable
part of the drainage is now carried off on the surface.
Southward from the edge of the highland there is a gradual slope
to the Gulf, the surface being varied only by low swells of sandy
soil. The St. Mark's River cuts across these sands in the south-
eastern corner of the county, part of its present course being due to
underground solution. The Wakulla River, having its origin in the
flatwoods, flows across the southern part of the county as a typical
pre-erosion stream, but is soon lost underground, to emerge at
length in Wakulla Spring, one of the finest large springs in the state.
Some of the small lakes are quite deep and constant, while the
majority are mere pine barren ponds, partially or entirely dried out
at times. Other depressions are swampy tracts known variously
as "bays," "galls," and "sloughs."
Soils. — As throughout the coastal plain, the soils are chiefly
types of sandy series, the Soil Survey (14) stating that only about
one-half square mile of soil as heavy as loam or clay would be found
in the land surface of the county. The hills are covered by soils
described as derived from the Lafayette formation, while the valleys
and less elevated portions are covered with Columbia sands depos-
ited during a late period of submergence.
i9'7l GANO— ECOLOGY OF FLORIDA 341
Of the Lafayette derivation, the Orangeburg fine sandy loam
and the Norfolk fine sandy loam are the most extensive, and repre-
sent 2 types found only within the coastal plain of southeastern
United States (i). The former is distributed chiefly in 2 belts
across the Gulf Coast states and also west of the Mississippi River,
constituting the higher lands. The Norfolk fine sandy loam extends
)rthern Florida and west to Texas. In topog-
from Virg
similar
are considered the most important for general agriculture, forming
the greater part of the so-called "clay hammock lands " (13),
characterized by a telling percentage of clay in their subsoils and
esteemed for their fertility. The subsoil of the Orangeburg gives
the designation of "red hills" so commonly used in descriptions
of southern Georgia and of northern Florida, for the freshly cut
or eroded subsoil is a bright red sandy clay. The subsoil of the
Norfolk is a yellow sandy clay or clay loam.
Of the sedimentary deposits, the Norfolk sand covers the largest
area, being the most widely distributed soil of the coastal plain
from New Jersey southward (1). It is characterized by low ele-
vation and generally level surface from the immediate shore line
inland.
Corresponding, then, with the 2 general topographic divisions
there are 2 general soil divisions, that of the more elevated regions
having clayey subsoil, while the rest is nearly pure sand.
Vegetation in relation to physiography
UPLANDS
Clay hammock lands
In the study of the upland on these soils, there are few evidences
of primeval forests, but it is easy to follow recent reforestation and
thus to gain an idea of the succession under present conditions.
The methods of agriculture as long practiced in these regions
soon exhausted the soil and led to clearing of fresh tracts. The
use of these for a few years and their abandonment and return to
forest afford object lessons of all stages of second growth. Also on
342 BOTANICAL GAZETTE [may
some
recently undisturbed; likewise on some of the old and extensive
estates groves have been preserved and illustrate what the forests
may have been before the civil war. Clearing and exhaustive
cotton growing soon reduce the humus and bring about soil vitia-
tion, which exposure intensifies, resulting in a more xerophytic
state.
The exposed Orangeburg soil readily washes, and plants can
get a hold on the steep bare slopes with difficulty. Soil lichens
and mosses, however, soon form a gray-green coating, especially if
partially shaded. Species of Cladonia and Baeomyces are among
these earth lichens.
Fields relapsing from tillage soon grow a mixture of ruderals
and native plants. Cenchrus carolinianus Walt., C. tribidoides L.,
Erianthus divaricatus Hitch., E. brevibarbis Michx., Andropogon
virginicus L., A. Elliottii Chapm., A. scoparitts Michx., Gerardia
purpurea L., G. fasciculata Ell., G. tenuifolia Vahl., A plo pappus
divaricatus Gray, and Eupatorium capillifolium Small, with pros-
trate species of Rubus (R. trivialis Michx. and R. cuneifolius
common
with
Of
these pines, P. echinata Mill, (short-leaved yellow pine) is by far
the most abundant, although other species occur, as P. Taeda L.
(loblolly or old-field pine), P. caribaea Morelet (Cuban or slash
pine), and occasionally P. clausa Sarg. (sand or spruce pine), and
palustris Mill
Q
Mill, (live oak) is a broad-leaved evergreen pioneer, and Diospyros
virginiana L. (persimmon) and Liquidambar Styraciflua L. (sweet
gum) are deciduous trees soon growing with the dominant pines.
Sassafras variifolium Ktze. and Prunus angustijolia Marsh, are
thicket formers. Pteris aquilina L. is an abundant fern character-
istic of these xerophytic pioneer stages of the old fields.
The pines which spring up in such numbers, if not disturbed,
grow rapidly, and on the whole uniformly, and comparatively soon
form a forest of trees of similar height and diameter. Where burn-
ing or pasturing does not interefere, a dense shrubbery quickly
develops, including a variety of seedling trees and shrubs. Of these
1917]
GANO— ECOLOGY OF FLORIDA
343
developing trees, oaks are most numerous, Q. jalcata Michx.
(Spanish or red oak) and Q. stellata Wang (post oak) being the
principal pioneers. Q. virginiana Mill, persists, being a tree of
almost every habitat, from hydro-mesophytic to xerophytic. When
forming groves of large, wide spreading trees, draped with Tilland-
sia usneoides L. (Spanish moss) and supporting on the trunks and
■-Q-
branches a growth of Poly podium poly podioides Hitch., this live
oak is the typical tree of the mesophytic "hammock," a term used
in these regions of the south to designate lands supporting a
forest growth of deciduous and broad-leaved evergreen species,
correlated with a rich and fertile soil (fig. 1). The evergreen Ilex
1 Ait. grows well in the shade of the pines; and Cornus
sometimes
opaca Ait.
jlorida L. d
forest, with some of the trunks 12-18 inches in diameter at 2 ft.
from the ground, the widely spreading tops meeting overhead,
while above them rise the pines.
n gust if oli
(wild
344
BOTANICAL GAZETTE
[may
crab) is a small tree characteristic of the pine wood borders and
more open parts.
Mingled with the oaks are hickories, Carya alba K. Koch being
the prevalent species, and a characteristic member of the develop-
ing oak forest. The mixed assemblage of small trees and taller
shrubs accompanying the oaks and hickories include Ilex vomitoria
Ait. (an evergreen), several species of Crataegus (especially C. con-
sanguinea BeadL, C. robur BeadL, C. panda BeadL), Rhus copal-
■
Una L., Callicarpa americana L., and V actinium arbor eum Marsh.
Low shrubs are Ceanothus americanus L., Gaylussacia dumosa
T. and G., Rosa humilis Marsh., and Yucca filamentosa L.; while
common woody vines with persistent or evergreen leaves are a
number of species of Smilax (S. pseudochina L., S. bona-nox L.,
S. glauca Walt.), Gelsemium semperoirens Ait., and Lonicera semper-
virens L.
The herbaceous growth in the pine forest, when undergrowth is
not disturbed, is not abundant, but in woodland burnt over or
cleared, grasses and sedges spring up and often make pasturage.
Blooming early in the spring, Oxalis stricta L., O. corniculata L. ?
Phlox pilosa L., Scutellaria integrifolia L., Salvia lyrata L., Houstonia
purpurea L., Specularia perfoliata A.DC, Antennaria plantagini-
folia Rich., Pyrrhopappus carolinianus DC, and Chrysogonum
virginianum L. are herbs which indicate xeromesophytic condi-
tions. In more mesophytic places Houstonia rotundifolia Michx.
and Mitchella re pens L. may be found in bloom at almost any date,
the latter with flowers and fruits at the same time.
There is no vernal flora, nor can a definite flowering season be
set, but there is overlapping and irregularity in the prolongation of
the blooming season, conditions related to the spring drought and
to the extended growing season due to the climatic causes. The
most showy season, so far as the herbs are concerned, is after the
summer rains, during the late summer and the fall, when Agrimonia
Eupatoria L., Schrankia uncinata Willd., Lespedeza hirta E1L,
L. striata H. and A., Z,. violacea Pers., Poly gala sanguinea L., P.
verticillata L., Helianthemum carolinianum Michx., Oenothera biennis
L., O. linearis Michx., Sanicula canadensis L., Gentiana villosa L.,
Asclepias verticillata L., A. variegata L., Trie host em a dichotomum
>
1917] GANO— ECOLOGY OF FLORIDA 345
L., Salvia azurea Lam., Penstemon laevigatas Ait., Gerardia flava L.,
G. purpurea L., Galium circaezans Michx., Eupatorium coelestinum
L., E. aromaticum L., E. album L. ; Liatris scariosa sqtiarrulosa
Gray, Chrysopsis mariana Nutt., Gnaphalium purpureum L., and
Solidago petiolaris Ait., make a representative list for the short-
leaved pine wood.
The succeeding stage in upland reforestation is that of the
oak-hickory forest, in which the characteristic xeromesophytic
oaks are dominant. Of these two oaks, Q.falcata Michx. seems the
more xerophytic, at least it appears on more exposed and drier
situations and soils, and slightly in advance of Q. stellata Wang.,
the other pioneer oak. But together, these with Carya alba K. Koch
dominate the forest which rapidly follows the short-leaved pines.
With the increasing mesophytic conditions (shade, humus,
moisture, bacterial, and fungal development), other oaks (Q. nigra
L., Q. laurifolia Michx., and Q. alba L.) appear. Other large trees
are Liquidamber Styraciflua L. and Nyssa sylvatica Marsh. The
undergrowth is composed of many seedlings of these species and
others, with the small trees and shrubs common to the pine forest,
as well as more mesophytic species, such as Ostrya virginiana
K. Koch, Cercis canadensis L., Aralia spinosa L., and Viburnum
rufiditlum Raf .
The appearance of young, Magnolia grandiflora L. and of Fagus
grandifolia caroliniana Fernald and Rehder indicates the approach
of the climax and of the transition to the magnolia-beech forest, in
which the broad-leaved evergreens and a variety of deciduous trees
assemble.
An undisturbed hammock forest of such mesophytic compo-
sition, and apparently representative of the climax capable of
development on the uplands, contains abundant magnolias of
stately proportions (60-80 ft.), equally large beeches, and Florida
sugar maples (A . floridanum Pax or A. saccharum floridanum Sarg.),
with intermixed live oaks, white oaks, red oaks (Q. texana Buckley),
basket oaks (Q. Michauxii Nutt.), sweet gums, big bud hickories,
and dogwood, with a few old and large short-leaved and Cuban
pines as relics. The abundance is approximately in the order
named, and all may be hung with Spanish moss. The shrubbery of
346 B0r.4AVC.-li GAZETTE [may
this forest includes Asimina parvijiora Dunal, Hamamelis virgin-
tana L., Evonymus americanus L., Stewartia Malachodendron L.,
A r alia spinosa L., Symplocos tinctoria L'Her., Osmanthus ameri-
canus Br., Viburnum rufidulum Raf., and V. nudum L., an assem-
blage of northern and southern species all about equally indicative
of similarly mesophytic habitats; while perhaps the most significant
thing is the occurrence of young beeches and magnolias, empha-
sizing the climax conditions.
The undergrowth and herbage are apparently related to the
prevalence of the magnolias and other heavily foliaged trees. If
these are dominant, the ground is freer of growth and covered with
the heavy and slowly decaying leaves. Mitchella re pens L. is a com-
mon floor covering. Root parasites are Conopholis americana Wallr.
and Epifagus virginiana Bart.; while Monotropa uniflora L. and
M . Hypopitys L. occur in abundance in the damp, shaded soil.
To summarize, the forest succession on clay soil of the upland,
as shown in phases of reforestation on limited areas but in all stages,
we see (i) pines, (2) oak-hickory forest, (3) deciduous broad-leaved
evergreen forest. In the pine forest, P. echinata Mill, is the domi-
nant species; in the oak-hickory forest, Q. falcata Michx. and Q-
stellata Wang, with C. alba K. Koch; in the climax forest, Magnolia
grandiflora L., Fagus grandifolia caroliniana Fernald and Rehder,
and a variety of associates.
,
Sandy soils
In comparison with the uplands of the northern part of the
county, those of the south seem like lowlands. Since their geo-
logical history has not been the same and the resultant topography
is not so distinct, the vegetational aspect also is different. The two
regions seem to exemplify two stages in the coastal plain develop-
ment, the older and the younger. The southern or younger part
typifies the marginal portion of the coast, of comparatively recent
emergence, and belonging quite entirely to pre-erosion topography,
being level, of low elevation, and covered with loose sandy deposits.
Almost the whole surface, therefore, may be considered as upland.
The base leveling of this region, supposing no future oscillatory
changes of importance, may require a prolonged period, the ero-
r
i9 T 7] GA NO— ECOLOGY OF FLORIDA
347
sive forces being capable of slight application, but it will not
com
seems
to the north. The vegetation
to small differences in elevation, into the so-called "scrub/' the
more
In a general
with the soil type
being associated with Sandhill soil, the pinelands with Norfolk
sands, and the flatwoods with Leon sands. For convenience, these
3 general divisions of the pre-erosion uplands will be discussed
separately.
Scrub oak forest. — The oak association seems to mark the
sandhill areas, which, owing to the porous sandy subsoil and the
lack of organic matter in the soil, would seem to be a decidedly
xerophytic habitat. Three small deciduous oaks and a scattering
of pines (P. palustris Mill, chiefly) make up the tree growth. Of
these oaks, Q. Catesbaei Michx, seems to be the most xerophytic,
as it is sometimes almost alone on the summits of the knolls or
ridges. Q. margaretta Ashe (suggested as a possible hybrid between
Q. stellata Wang, and Q. alba L. and sometimes, as noted on the
more fertile soils, apparently intergrading into well grown Q. stellata
Wang.) appears in the intermediate positions; while Q. cinerea
Michx. grows near the bases of slopes. They intermingle in varying
proportions over most of the area, growing to about the same
height (15-20 ft.), with many scrubby branches, making when
thickly planted a scrubby thicket. Q. geminata Small, a scrubby
live oak, is another species occurring on sandy soil, usually in
situations near water or damp places. Q. virginiana Mill, and
Diospyros virginiana L. also grow on the sandhills.
Shrubs are mostly low and with evergreen or persistent foliage,
as Ceratiola ericoides Michx., Leiophyllam bitxifolium Ell., V acti-
nium Myrsinites Lam., V. stamineum L., V. neglectum Fernald.
Asimina pygmaea Dunal (with deciduous though coriaceous leaves),
Ceanothus microphallus Michx., and V actinium tenellum Ait. are
shrubs of the dry
grow
great
Tufts of scattered wire or
grass
34§ BOTANICAL GAZETTE [may
being species of Andropogon and of Aristida. Pier is aquilina L. is
abundant also. In the spring, Cassia Chamaecrista L., C. nicti-
tans, L., Lupinus perennis L., L. villosus Willd., Tepkrosia vir-
giniana Pers., T. spicata T. and G., Baptisia simplicifolia Croom, B.
lanceolata Ell., Euphorbia corollata L., E. Ipecacuanhae L., Croton
argyranthemus Michx., Jatropha stimulosa Michx., Amsonia ciliata
Walt., Scutellaria integrifolia L., and Chrysogonum virginianum L.
are early bloomers, the Leguminosae being most abundantly repre-
sented. Through the summer and fall a characteristic and repre-
sentative list includes Eriogonum tomentosum Michx., Eriogonum
hngifolium Xutt., Polygonella gracilis Meisn., Petalostemum corym-
bosum Michx., Desmodium rigidum DC, Rhynchosia simplicifolia
Wood, Hypericum Drummondii Grev. and Hook., Angelica dentata
Coult. and Rose, Asclepias tuber osa L., Verbena angustifolia Michx.,
V. caroliniana Michx., Gerardia fasciculata Ell., Elephantopus
tomentosus L., Eupatorium aromaticum L., Trilisa odoratissima
Cass., T. paniculata Cass., Kuhnia eupatorioides L., Liatris tenui-
folia Nutt., L. elegans Willd., Chrysopsis gr aminif olia Nutt., C.
gossypina Nutt., C. mariana Nutt., Berlandiera texana DC, Soli-
dago odora Ait., Aster lateriflorus Britt., A. concolor L., Silphium
Asteriscus L., Helianthus radula T. and G., H. mollis Lam., and
Palafoxia integrifolia T. and G. Many of these are perennials with
prostrate or rosette-forming habit, or with pubescent to flocculent
coating on leaves and stems, or, as in the case of the species of
Croton y a scaly coating or with thick and narrow leaves.
Pinelands. — Passing to the somewhat lower Norfolk sand,
which generally surrounds the islands of Sandhill, the transition
is marked by the increase in long-leaved pines. The 3 scrub oaks
continue as more or less abundant members of the pine forest
(fig. 2). P. palustris Mill, and P. caribaea Morelet are the pines,
both of them valuable species for their turpentine and for their
timber. Quercus virginiana Mill, and the xerophytic oak Q.
marilandica Moench. occur occasionally, also Q. pumila Walt., a
low, shrublike species. Crataegus panda Beadl., the common haw-
thorn of the sands in this vicinity and noticeable for its dark, deeply
checked bark and irregular crooked-branched habit, and Bumelia
lanuginosa Pers. are small trees. Castanea pumila Mill- is com-
1917]
GAXO— ECOLOGY OF FLORIDA
349
f
I
mon in some places, making groves of trees or a low, shrubby
growth, spreading by stolons and rapidly covering a considerable
area. Diospyros virginiana L. is also a tree of these sands, but
more frequent as second growth with the short-leaved pines, live
oaks, post oaks, Spanish oaks, and sweet gums, as on cleared land
which has been cultivated for a time and allowed to revert to forest.
In this reforesting the early stages thus resemble those on the
hills, but to these clearings the long-leaved pines with the scrub
Fig. 2. — Long-leaved pine forest on Norfolk sand
may
and may ming! _
cannot Ions: com
return. It is on such more fertile spots or where
improvement of the soil that the xerophvtic scrub
Q. margaretta Ashe, appear to grow to better size
with the xeromesophytic oaks, but
The
sometime
difference in topography, soil, or drain
From the
that these oaks may ap
they appear in the more
mits of the ridges of the sandv soil, it mav be that they succeed
350 BOTANICAL GAZETTE [may
better than pines on dry, sterile sand, so that when the pines are
removed from such lands, the scrub oaks more quickly take pos-
session, while the pines return more slowly and scatteringly. On
the other hand, with improved or more mesophytic conditions, the
scrub oaks are soon replaced by pines, xeromesophytic oaks, and
the succeeding mixed forest.
There seem, therefore, to be two possible phases of succession
on the sandy soils. On the more sterile sands, the scrub oaks may
be the pioneers before the long-leaved pines; or, if the pines be
removed, these oaks may follow, to give place, with improvement
of soil and moisture, to xeromesophytic pines and oaks, and then
to the oak-hickory forest, leading toward the climax forest sooner
or later. But on soil neither excessively drained nor poorly drained,
the scrub oaks will accompany the long-leaved pines, yielding,
where more mesophytic growth is favored, to the short-leaved
pines and their following as outlined. Groves of short-leaved pines
are not uncommon within the long-leaved pine association, especially
where there may be some admixture of clay, as when the Norfolk
sand is in close association with such types of soils as the Orange-
burg and Norfolk fine sandy loams.
The growth of shrubs in these long-leaved pine woods is notice-
ably scanty and the species relatively few. The frequent burning
over of these woods and their utilization for turpentine no doubt
prevent a natural growth from starting. However, the contrast
with the short-leaved pine forest on the hills is very great in this
respect, and the xerophytic conditions are correspondingly greater;
hence succession or the renewal of the forest is delayed. The
shrubs noted commonly in the pinewoods on sandy soils are Rhus
copallina L., Ceanothus americanus L., Ilex vomitoria Ait., V ac-
tinium arboreum Marsh., V. virgatum Ait., V. stamineum L., V.
Myrsinites Lam., V \ neglectum Fernald, Leiophyllum buxifohum
Ell., Kalmia hirsuta Walt., and Gaylussacia dumosa T. and G-,
the Ericaceae being the most numerous. The variety of herbs in
these pine forests is striking, many of them being those of the
"scrub," the families prominently represented being Compositae,
Leguminosae, Euphorbiaceae, Scrophulariaceae, Polygalaceae, and
Labiatae, chiefly xerophytic species.
. 1917]
GANO— ECOLOGY OF FLORIDA
351
Flatwoods. — From
the change is indicated, not by the prevailing tree growth, but by
the shrubs and herbs.
mark
difference
(fig- 3)- The long-leaved pines continue to form the forest, appar-
ently succeeding best on these poorly drained sands. This is
1
Fig. 3. — In foreground saw palmettos and wire grasses and herbs characteristic
> * ... - 1 _ • * •■• m « ft - . 1 1 • . •
association
perhaps the explanation of the specific name of Pin us palitstris
Mill., although this particular pine is by no means a typical swamp
tree, as for example is P. serotina Michx., nor is it as tolerant of
time
shrubby growth
ergreen
Fires
352 BOTANICAL GAZETTE [may
I
may be one of the chief causes preventing development of under-
growth, but the presence of these low shrubs adjoining bays and
ponds, where fires have been able to do small damage to the natural
growth, seems to prove the character of the shrubbery. Dwarf
oaks are common (Q. myrtifolia Willd., Q. minima Small, and Q.
nana Willd.), with persistent, leathery leaves and mostly bearing
abundant fruits. Myrica cerifera pumila Michx., M. carolinensis
Mill., Ilex glabra Gray, Hypericum myrtifolium Lam., H. galioides
Lam., H. aspalathoides Willd., H. opacum T. and G., and Kalmia
hirsuta Walt, are other shrubs with persistent foliage. Pyrus
arbutifolia L. f., Rhododendron nudiflorum Torr., R. viscosum Torr.,
Lyonia nitida Fernald, Andromeda ferruginea Walt., Vaccinium
stamineiim L., and V. Myrsinites Lam. are also shrubs of the damp
■
to wet sands.
The most conspicuous index, however, of subsoil more or less
saturated is Serenoa serrulata Hook. f. (saw palmetto). As soon
as this palmetto appears with the turpentine pines, poor drainage
is to be inferred. The herbs also are strikingly characteristic of
undrained soil with its lack of aeration and consequently of assimi-
lable nitrogenous substances. The Leguminosae, so abundantly
represented on the Sandhill soil and in the long-leaved pinewoods
on the dry sands, do not appear. Besides the grasses and Com-
positae, the families most in evidence here are Eriocaulaceae,
Juncaceae, Liliaceae, Orchidaceae, Sarraceniaceae, Droseraceae,
Polygalaceae, Melastomaceae, Onagraceae, Gentianaceae, Scrophu-
lariaceae, and Lentibulariaceae. Representatives of these familes
are Eriocaulon decangulare L., E. compressum Lam., Juncus Elliot-
tii Chapm., /. debilis Gray, Xerophyllum asphodeloides Nutt.,
Spiranthes praecox Wats., Calopogon pulchellus R. Br., Sarracenia
flava L., 5. psittacina Michx., 5. Drummondii Croom, 5. minor
Walt., Drosera brevifolia Pursh, Poly gala lutea L., Rhexia mariana
L., R. glabella Michx., R. virginica L., R. ciliosa Michx., Ludvigia
pilosa Walt., L. alter nifolia L. ? Viola lanceolata L., Eryngium
*
virgatum Lam., Sabatia Elliottii Steud., S. paniculata Pursh, Gen-
tiana Porphyrio G. Gmel., Gerardia filifolia Nutt., Seymeria tenui-
jolia Pursh, Pinguicula lutea Walt., P. pumila Michx., Utricularia
subulata L., and U. comuta Michx. The species of Sarracenia
%
I9I7J GANO— ECOLOGY OF FLORIDA 353
pecuroides
growth of Lycopodium
other mosses. Osmunda cinnamomea L., 0. regalis L., Onoclea
sensibilis L., Woodwardia areolata Moore, and W. virginica Sm. are
typical bog hydromesophytes and abundant ferns of this habitat.
A complete analysis of the flora of these low woods probably would
include a longer list than for any other habitat in the county, and
would be evidence of the edaphic character of this association.
Summarizing
dominant
most
palust
meso
Mill, and P. caribaea Morelet, the latter ranges more widely
in habitat, occurring from mesophytic to hydrophytic habitats,
even enduring inundation. The former is not a typical swamp
tree nor does it succeed well in soil subject to inundation for any
length of time. On this account, probably, P. caribaea Morelet,
a dominant species for the southern Florida pinewoods, is reported
to be gradually replacing P. palustris farther north. On meso-
phytic soils these pines are displaced by the more
species, while on the drier soils or excessively drained sands the
scrub oaks succeed better and take possession. P. palustris belongs
typically, therefore, to sandy soils with subsoil well drained to
saturated or forming hardpan, soils in which few other trees would
flourish. Since such habitats predominate, owing to the present
physiographic conditions on the coastal plain, the present long-
leaved pine forest may be looked upon as edaphic, the species of
pines, within their respective climatic ranges, being pioneers in
these comparatively primitive habitats.
PRE-EROSION DEPRESSIONS
Throughout the coastal plain, depressions not resulting from
recent erosive processes present a variety of edaphic studies.
Many of these low places are filled for all or part of the time with
surface water, or they may be sufficiently depressed below the
water table to contain a permanent amount of water. Others may
be mere swampy or boggy tracts, or during dry seasons prairie-like.
The relation of these surface features to the formation of peat,
i
354 BOTANICAL GAZETTE [may
especially in Florida, has been investigated and reported by Harper
(6), whose descriptive classification of habitats and extensive lists
of peat-forming plants present a summary of the plant associations
of the various sorts of swamps, marshes, bogs, ponds, lakes, and
streams.
The water of these pre-erosion depressions, with their (usually)
sandy basins, is characteristically dark-colored, appearing blackish
matter
or less acid reaction.
Lakes, ponds, and streams
The vegetation of the ponds and of the slowly moving waters of
the sluggish little streams is not decidedly different, differences
depending rather on the depth of water and on the amount of
movement. In shallow, permanent water the aquatics are arranged
in the usual zonation, from those submerged or floating to those
rooted in the muck or sand of the bottoms and to the amphibious
plants of the margins.
Lists of aquatics for the ponds and lakes include among the
submerged and floating forms Potamogeton spp., Ceratophyl-
lum denier sum L., Myriophyllum heter o phyllum Michx., Lemna
valdiviana Philippi, Castalia odorata Woodv. and Wood (and the
variety C. odorata gigantea Fernald), Nymphaea advena Ait.,
Brasenia Schreiberi GmeL, Nelumbo lutea Pers., Nymphoides aqua-
ticum Fernald, Utricularia inflata Walt., U. biflora Lam., and U.
purpurea Walt.
In marginal zones, Panicum hemitomum Schult., P. condensum
Nash, Dalichium arundinaceum Britt., Eriocaulon decangidare L.,
E. compressum Lam., Mayaca Aubleti Michx., and Bacopa caro-
liniana Robinson usually grow in shallow water ; while the common
strand plants are Fuirena squarrosa Michx., Hemicarpha micran-
tha Britt., Rkynchospora corniculata Gray, Syngonanthus flavidulus
Ruhland, Drosera brevifolia Pursh, Hypericum virginicum L., H.
gentianoides BSP., Hydrocotyle umbellata L., Bartonia spp., Diodia
virginiana L., D. tetragona Walt., Spermacoce parviflora Gray,
Houstonia angustifolia Michx., Lobelia gland Hlosa Walt., and
Pluchea foetida DC. The cypresses (Taxodium distichum Rich, or
*9 J 7l
GANO— ECOLOGY OF FLORIDA
355
T. distichum imbricarium Sarg.) when present are the chief tree
pioneers in the ponds, advancing farthest into the deeper water,
reaching from the zone of high water, perhaps, to the extreme limit
of the occasional low water, into the zone of water lilies and sub-
merged aquatics (fig. 4), Cephalanthus occidentalis L. is a close
companion of the cypresses and advances into the standing water
•\
1
t'
&k i
:
■<*
*•
-*.
■
Jt
Fig. 4. — Cypresses advancing into deeper water
as a shrub pioneer. The hydrophytic species of Nyssa (2V. aquatica
L., N. sylvatica biflora Sarg., and the less frequent or local N.
Ogecliee Marsh.), germinating and growing in shallow water, may
accompany the cypresses or may spread over the shallow ponds to
form the so-called "gum swamps" (fig. 5).
Approaching the shores or in the shallow water of the margins,
these trees are joined or surrounded by a zone of marginal shrubs
and small trees. Among those which commonly grow in this zone
are Salix longipes Anders., Magnolia virginiana L., Per sea pubescens
'356
BOTANICAL GAZETTE
[may
Sarg., Crataegus viridis L., C. aestivalis T. and G., Cyrilla racemi-
jlara L., Cliftonia monophylla Britt., Ilex Cassine myrtifolia Sarg.,
Acer rubrum L., A. rubrum tridens Wood, Hypericum fasciculatum
p
?
Fig. 5. — Gums (Xyssa spp.) forming a gum swamp; trees show swollen bases,
and a seedling in center of picture has germinated and is growing in the dark water.
Lam., H. myrtifoliitm Lam., H. microsepalum Gray, Lyonia nitida
Fernald, and Leucothoe racemosa Gray.
On the edge of moist but not inundated soil, species of Myrica
may grow, while Serenoa serrulata Hook, and Ilex glabra Gray mark
1917]
GANO— ECOLOGY OF FLORIDA
357
the line of high water. Here live oaks, water oaks, sweet gums,
and the swamp and pond pines appear, beginning a meadow or
immediate
(fig. 6) .
lax Walteri
laurifolia ]
on moist soil.
Fig. 6. — Lake margin, showing cypresses in water, shrub zone within range of
high water, and live oaks on rising ground.
Ponds which dry out during the season are often encircled by
marginal
it into a
may fill
" On areas of clayey soils, willows,
maples, sweet gums, and button bushes are the commoner marginal
trees and shrubs; while the chief variations in ponds on sandy soils
are due to the presence of cypresses or of gums as the tree pioneers,
358 BOTANICAL GAZETTE [may
composition of the shrubbery about the mar
ing climax
much
from the ponds as described. The aquatics in moving water are
not so numerous, but the shore growth is more varied, and may
grade, with the drainage, into bordering strips of meadow on low-
land hammock by which the streamways are conspicuously marked
from the adjoining pine forests.
Waters flowing from limestone springs and which are clear and
more calcareous have a somewhat different vegetation from that
of the acid, brown waters of the other streams- Liquidambar
Styraciflua L. is a tree of the sometimes inundated margins, and
Ulmns americana L., Fraxinus caroliniana Mill., F. profunda Bush,
Quercus nigra L., Salix longipes Britton, Acer rubrum L., Ilex
Cassine L., C omits stricta Lam., and Cephalanthus Occident alls L.
are common. Canes (Arundinaria tecta Muhl.), reeds (Phragmites
communis Trin.), and saw grass (Cladium jamaicense Crantz),
with bulrushes (Scirpus spp.) are marginal marsh plants..
Flowing waters.
p
ampy borders of varying
the almost invariable ace
pre-erosion branches, creeks, and rivers, the width of the overflow
area depending upon the topography and upon the consequent
drainage basin, and upon the volume of the stream. By the
accumulation of humus and as improved drainage is secured, these
meadow areas in many cases tend to extend outward or upward
and often come to occupy wider spaces than would be explained
solely by the fluctuations of the stream. From the adjoining vegeta-
tion they are marked off by species ranging from hydrophytic to
extremely mesophytic. The swampy character extends as far as
the soil continues saturated, and in this zone there occur trees of
the pond margins, such as cypresses, gums, willows, birches, ashes,
water hickory, and water elm (Planer a aquatica J. F. Gmel.).
On slightly rising ground, but still within range of the high
water, there occur pines (P. caribaea Morelet, P. serotina Michx.,
P. palustris Mill., and P. glabra Walt.), with a variety of oaks, such
1917]
GA NO— ECOLOGY OF FLORIDA
359
as Q. nigra L., Q. laurifolia Michx., Q. Michauxii Nutt., also Car-
pinus caroliniana Walt, and Liquidambar Styraciflua L. (fig. 7).
Many shrubs and small trees belong to these swampy margins,
making a dense growth to the water's edge, with intermingling
Fig. 7.— Exterior view of Ocklocknee River meadow, showing dense deciduous
growth at swampy edges; pines coming in on higher ground.
myricas, bays, and mixed shrubbery, among which are I tea vir-
ginica L., Rhus Vernix L., Cyrilla racemiflora L.,C. paruijolia Raf.,
Sebastiana ligustrina Mill., Ilex Cassine L., /. decidua Walt., Cornus
stricta Lam., Clethra alnifolia L., Rhododendron spp., Androtneda
ferrnginea Walt., Cephalanthus Occident alls L., Pinckneya pubens
360 BOTANICAL GAZETTE [may
Michx.; with also a variety of lianas such as Stnilax Walteri
Pursh, S. laurifolia L., Berchemia scandens Trel., Trachelospermiim
difforme Gray, and Aster carolinianus Walt.
Beyond reach of frequent inundations, in soil enriched by
accumulation of humus, the most mesophytic stage is reached, and
the meadow grades into the lowland or river hammock, where a
mixed forest of many species develops. Fagus grandifolia caro-
liniana Fernald and Rehder and Magnolia grandiflora L. may
appear here, with Celtis mississip piensis Bosc, Liriodendron Ttdipi-
fera L., Halesia Carolina L., H. diptera Ell., Chionanthus virginica
L., and others, forming rich forests of varying composition
along the streams. In these forests is an assemblage of meso-
phytic shrubs, such as Alnus rugosa Spreng., PLamamelis virginiana
L., Aesculus Pavia L., Styrax spp., and Viburnum spp., with lianas
and climbing shrubs, such as Decumaria barbara L., Wistaria fru-
tescens Poir., Sageretia Michauxii Brong., Rhus Toxicodendron L.,
P seder a quinquefolia Greene, Cissus Ampelopsis Pers., Cissus
arbor ea Des Moulins, Vitis rotundifolia Michx., V. aestivalis
Michx., Bignonia capreolata L., Tecoma radicans Juss., and the
mesophytic species of Smilax. Ferns of the swampy or wetter
soils are Osmitnda spp., Onoclea sensibilis L., and Woodwardia
spp. Of more mesophytic habit are Aspidium Thelypteris Sw.,
A. patens Sw., and Asplenium Filix-femina Bernh. On the water
oaks, black gums, and various other trees Phoradendron flavescens
Nutt. is abundant, and also Tillandsia usneoides L., the ever common
epiphyte.
It is to be noted that the character of a well developed stream
or river hammock of the region is quite the same wherever occur-
ring and within the boundaries of whatever soils. The telescoping
of swamp and hammock complicates the successional phases and is
usually extreme, since even slight differences in elevation or drain-
age are sufficient to modify- the vegetation extensively.
Quiet waters.— The so-called " bays' 7 are examples of shallow
undrained swamps supporting a more or less dense growth of shrubs
or small trees. Magnolia virginiana L., Per sea pubescens Sarg.,
and P. Borbonia Spreng. are the real "bays," but the list of plants
for these boggy ponds includes a variety of other species, as cyrillas,
\
1917]
GANO— ECOLOGY OF FLORIDA
361
f
grapes, hollies, hypericums, hawthorns, and ericads, and such trees
as cypresses, gums, and slash and swamp pines.
There is little suggestion of any definite succession in the com-
position of the bay or similar swamp. However, Magnolia vir-
giniana L., Per sea pubescens Sarg., and Ilex Cassine myrtifolia
Sarg. seem to advance into the more hydrophytic portions and
appear near the center of the swamp surrounded or followed by
the grapes, ericads, and myricas;
while Ilex glabra Gray, /. hicida
T. and G., and Serenoa serridata
Hook., with Hypericum spp. grow
beyond the standing water. Fre-
quently Ilex Cassine myrtifolia
Sarg. is so abundant as to make a
fairly impenetrable thicket.
An undrained pond may de-
velop into a cypress swamp, the
cypresses growing as
closely
as
Fig. 8. — Cypresses advancing into
waters of an undrained pond, grad-
ually forming a cypress swamp.
their swollen bases and groups of
projecting knees permit (fig. 8).
Around the margin of such a
swamp there may be a mingling of oaks, gums, and pines, but more
frequently there is a sharp transition to the forest of the upland
adjacent, and the edge of the swamp is abruptly marked by the
ranks of flat-topped cypresses. When the gums mingle with the
cypresses or are the most abundant or only trees, a gum swamp
develops, these trees also having swollen or bulging bases. 77/-
landsia usneoides L. gives a characteristic touch to their appear-
ance, especially in winter when the trees are leafless.
The herbs of such swamps are mainly those of pond margin-
and of the flatwoods, as Panicum hemitomum Schutts, P. condensum
N*ash, Aristida spiciformis Ell., Ekockoris spp., Fmrma squarrasa
Michx., Rhynchospara spp., Eriocaulon spp., May oca Aubleti
Michx., Burmannia bijlora L., Polygala cymosa Walt., P. ramosa
Ell., Hypericum petiolatum Walt., H. virginicum L., Ludvigia alterni-
folia L., L. glandidosa Walt., Gerardia
amoena Michx., and L. glandidosa Walt.
Nutt., Lobelia
362 BOTANICAL GAZETTE [may
In certain low places, as at the bases of slopes, water may ooze
through the sandy soil to collect on the surface in little pools or
pockets, with intervening hammocks of dark muck, or may slowly .
drain away, sometimes forming the source of a small stream. In
this way small branches or considerable tributaries may originate,
and by their union form creeks or small rivers. In other cases 1
sloughs and ponds may be formed, such boggy spots often being
designated "galls." In vegetation they resemble the bays, often
surrounded by or advancing to a hammock stage by the accumu-
lation of humus and the gradual building up of the soil.
Bayheads scarcely differ from these, also being the sources of
small branches. In these, typical trees are Magnolia virginiana L.
and Per sea pubescens Sarg., with a bordering shrubbery of more or
less mesophytic character.
Sloughs are low, flat passageways between swamps or bodies of
water. In these passageways the water may be still or but slowly
moving, while during the dry season they may be entirely dried
out. Cypresses, sour gums, swamp pines, and swamp maples are
common slough trees, with live oaks, water oaks, holly, and sweet
gums on the edges. Swamp shrubs, including a variety of the en-
cads, cyrillas, gallberries, hypericums, with the saw palmetto, out
of reach of the standing water, are numerous.
Prairies
'
comparable to swamps
face and lacking surfac
may
times
vegetation consists typically of herbaceous associations, especially
grasses. No
pography under description here, although many
l and lakes may temporarily become prairie-like,
he dry seasons being overgrown with grasses and
which introduced nlants. as weeds, make a mis-
cellaneous assemblage.
EROSION TOPOGRAPHY
The northern part of Leon County, having been exposed prob-
ably as long as any other section of Florida or of the immediate Gulf
1917] GANO— ECOLOGY OF FLORIDA 363
I
in
illustrations of erosion topography. The conditions are unusual,
however, since the presence of limestone so near to the surface has
brought about the development of extensive subterranean as well
as surface erosion, and the topographic features are thus modified
)licate ecological analysis. In considering
com
may
largely due to the underground erosion. The lakes, sinkholes, and
enclosed valleys seem evidence of this.
Surface erosion
Branches and creeks. — The trough of almost every valley
has a waterway marked by an aggregation of trees and shrubs.
The stream is usually an insignificant affair so far as the amount of
movement of the water is concerned, and consequently the erosive
work accomplished by such a stream is slight. Its course may be
found to lead, by a slight rise, to a bayhead where the water is
seeping from the base of a slope; or it may issue from a spring
whence the water may flow across the ground, spreading out into
a miry tract; or, as in the clayey soil of the hills, a definite channel
will be cut or gullied down the slope; or the spring will eat back
into the hill as a narrow ravine and a small clay canyon thus be
cut along the steeper part of the grade. The erosion work lessens
as the level is reached, the washing and gullying of the steep banks
grade and widen them, and in this way the little streams are
gradually bringing the soils of the hills to the valleys.
Ravines. — In the shady and moist ravines there grow numerous
liverworts and mosses, with soil lichens in the upper zone and with
ferns along the edges and in the niches. Of the ferns, Paly podium
polypdioides Hitch, grows on the moist clay banks, also Asplenium
platynearon Oakes, A. resiliens Kunze., Polystichum acrostic hoides
Schott., Aspidium Thelypteris Sw., and A. patens Sw. As the
stream broadens and shallows and the banks are lowered, reeds,
canes, and marsh grasses border the edges, while trees and shrubs
develop to form a meadow hammock.
Rivers.— The Ocklocknee River is an example of an extended
stream, rising in Georgia and cutting its way across the latest
364 BOTAXICAL GAZETTE [may
deposits of the coast- For most of its course along the western
border of Leon County its banks are edged by bluffs of varying
elevation (50-100 ft. above sea-level). These are apparently the
ancient banks, eroded during a previous period. At places these
bluffs approach close to the present low banks, so that the valley
varies in width. The erosion work of the river is of small impor-
tance, and in its bordering meadow and overflow land it resembles
a pre-erosion stream. The low bluffs are generally well wooded
and the undergrwoth is often denser and of a more mesophytic
type than is that of the upland forest.
Examples of small erosion creeks are to be seen in the south-
western edge of the county, where a series of drainage streams flow
from the bays on the Leon sand across the strip of Norfolk sand to
empty into the Ocklocknee River, and have cut ravine-like valleys
in the sands, in which the most mesophytic trees, including Magnolia
grandi flora L., Fagus grandifolia caroliniana Fernald and Rehder.
Liriodendron Tulipifera L., Carya alba K. Koch, Acer spp., Carpinus
caroliniana Walt., and Prunus caroliniana Mill., grow with a rich
undergrowth. Entering one of these eroded valleys from the
upland of monotonous pine forests, one witnesses the extremes
which the region can support.
Lakes. — The surface erosion along the shores of the larger lakes
is of small importance, as the shores are usually sloping and the
wave action is slight. The trees of the uplands may extend to the
water's edge or there may be tracts of fine hammock forest. Other
lakes resemble slow fluctuating streams, with cypresses in the
shallow water.
Subterranean erosion
The underground solution and the resultant caving in or settling
of the ground surface continue to play a part in modifying the
topography.
Sinkholes. — The formation of sinkholes may take place sud-
denly and expose the limestone, forming depressions, usually cir-
cular, varying in size and depth. In case there is no opening
through which the water may reach an underground channel, the
rainfall and the surface waters mav accumulate to form a pond-
I
19 1 7] GANO— ECOLOGY OF FLORIDA 365
In such sinks the water rises and falls with the amount of precipi-
tation and surface drainage. Other sinks are dry, having one or
more openings in connection with the underground drainage system.
The cliffs and ledges of limestone, if exposed, soon wear off, soil
collects, and gradually the sides become overgrown. The soil
om
m
moisture favoring the growth of su<
d mosses may be found on the damp
Liver-
sink and often in the crevices of the sides. Adiantum capillus-
veneris L. belongs to such situations, as also Poly podium polypo-
dioides Hitchc, Asplenium platyneuron Oakes, and Polystichum
acrostic hoides Schott.
Opelismen
setarius L. are grasses in the shady ravine-like situations, as pioneers
on the sides.
If the sink contains water, pond plants will enter and cypresses
or gums may grow. If the base is covered or finally filled with
soil, water oaks, live oaks, sweet gums, dogwood, and holly are
common sinkhole plants. White oaks, red maples, black gums, and
sweet gums are other trees occurring about the sinkhole margins.
Springs. — Many springs are the results of channels in the lime-
stones, occurring where the streams emerge from underground.
In the clear, cool, calcareous water of such springs there is not
much plant growth, although around the margins are grasses,
sedges, sagittarias, and reeds.
Lakes and ponds. — The relation of the large lakes to sink-
hole formation has been mentioned, sinks or openings occurring in
their basins through which the more or less complete drainage of
the waters of the lake may take place suddenly or gradually.
When these sinks become closed by obstructions or stoppage, the
water will again fill the basins (12). By the drainage of such lakes,
forest stage.
become p:
gradually
Streams. — Underground channels sometimes become surface
I in of the roof of the cavern. Frequently
streams by the cavin
a section may be left
Such is the case
366 * BOTANICAL GAZETTE [may
with the St. Mark's River, which emerges from a subterranean
course as a series of sinklike ponds, and finally as a surface stream
flowing across the sands to the Gulf. At the natural bridge the
banks are definite and rise directly from the water level. A rich
hammock borders the banks, the trees and shrubs growing close
to the water's edge.
Summary
This local study of the Gulf section of the coastal plain may
serve to suggest several points in the successional history of the
plant associations of the region. Extremes of xerophytic, hydro-
meso
most
by the long-leaved pine
oak forest of sterile, sandy soil. The most mesophytic associ
is that of the hammocks, occurring on the upland as the c
and also as a temporary climax in the river valleys, being com
and evergreen, of which
difolia
most significant deciduous tree, and Magnolia grandiflora L. the
principal tree among the broad-leaved evergreens. Between these
two extremes are the gradations from pioneer pines through the
pine-oak and oak-hickory stages. Telescoping and rapid growth
in the later stages are characteristic and confusing.
The long-leaved pine-saw palmetto association on the flat,
poorly drained sands presents a large edaphic problem. With
improvement in drainage, aeration of the soil, and consequent pro-
motion of soil organisms and their work, the change to a mixed
forest can take place, as is seen along the streams as well as in local
hammocks which have evidently been built up gradually. Drain-
palmetto
into association with the long-leaved pines, and the succession out-
lined from dry pine woods to the climax forest will naturally follow.
With slight depression of the surface a change to a moorlike swamp
results.
The various types of swamps, characterized by the prevailing
species, as the cypress swamps, gum bogs, pine swamps, and bays,
and their transitions to the surrounding forest, furnish opportunities
for intensive studies.
*
I
1917] GANO— ECOLOGY OF FLORIDA 367
Comparative observations
*
In considering the upland forests in their successional stages,
data concerning the evaporation, soil moisture, and certain climatic
factors, and their relation to the associations discussed, have been
collected. Evaporation records were secured by the use of Living-
ston atmometers, following the investigations of Fuller (4) and
others. Rain-correcting valves were used, the cups were kept
same
ingly.
meso
type, in a Spanish oak-post oak-hickory forest, in a short-leaved
pine forest, in a beech opening in the short-leaved pine forest, in
the dry pine woods (long-leaved pines), in the scrub oaks associa-
tion, and in the flatwoods. Meadow stations were also placed,
but their records are not complete. The stations were located in
as nearly typical situations as possible, the atmometers in each case
being placed at the surface of the ground. All records demonstrate
a constantly high evaporation as one of the climatic results, and all
show a general relation between the evaporation and precipitation
marked maxima
maj
winter and the summer
early May dry season, 1
evident in late September and early October, after the summer rains
have ceased. All records show a sudden rise in spring from the
lowest point in December or January to the April or May maximum
(June for the long-leaved pine forest) . This corresponds generally
to the period of the vernation of the deciduous species and to the
renewal of foliage by many of the evergreens. Winter records for
the highland stations were uninterrupted by frost through two
consecutive winters, but each lowland station suffered once or
twice each winter.
Of the upland stations, the average daily evaporation is lowest
for the mesophytic climax (magnolia-beech) forest, being 8.5 cc.
daily, estimated for a period during which an unbroken record was
obtained from December 24 to May 1; this is the most critical
Period, including from the January minimum to the April maximum.
same period of time
ave
36S
BOTANICAL GAZETTE
[may
a record of 9.9 cc; the beechwood n.2icc; the short-leaved
pines 11.67 cc; the long-leaved pines on
Norfolk
order
essentially that in which the successional changes as observed occur,
from the xerophytic pines and oaks through the xeromesophytic
forest (fig. o). The beech wood, it
pines and oaks to the climax forest (fig. 9).
must be noted, was subject to pasturing and gave evidence of
Fig. 9.
evaporation
in (1) mesophytic climax forest; (2) flatwoods; (3) Spanish oak-post oak-hickory
forest; (4) short-leaved pine forest; (5) pastured beech forest; (6) scrub oak forest;
(7) long-leaved pine forest.
recent burning (probably to promote pasturage), being quite free
of undergrowth. Cattle and hogs grazed through this forest and
Erechtites hieracifolia Raf . appeared among the herbs.
On the basis, however, of the average rate of evaporation esti-
mated for the year, the order is changed. The Spanish oak-post
oak association has an evaporation rate very close to that of the
short-leaved pines, being 14 .00 cc. daily for the former and 14.22 cc
for the latter. Both of these stations were observed without a
break from September 191 2 to May 17, 1914, and their averages
taken accordingly. The two stations are alike in that each has
t
191 7] GAXO— ECOLOGY OF FLORIDA 369
a dense undergrowth, that of the pine woods being if anything
denser than that of the oak forest; indeed, the pine forest is well on
its way toward the oak stage. However, there is a difference when
the winter and the summer averages are considered. Estimated
for the period from June to November, the season during which
full foliage of deciduous trees is a large factor, the daily rate for the
oaks is 12 .49 cc. and for the pines 13 .8 cc. In winter (November
to June), from the time when the oaks are leafless until they attain
full summer foliage, the rates are 15 .69 cc. daily for the oaks and
13 .70 cc. for the pines. In the beech woods during these seasons,
the rates are 13.4CC. daily for the summer and 17.8 cc. daily for
winter, thus showing an approximation to the pines in summer and
greater evaporation than either pines or oaks in winter.
The scrub oaks and long-leaved pines behave differently.
These oaks average 13 .95 cc. for summer (comparable to the short-
leaved pines and the open beech woods) and 14. 1 cc. for winter;
while the long-leaved pines on dry sand show the highest rates,
18.25 cc. for summer and 19.2 cc. daily for winter. The scrub
oaks and the long-leaved pines have respectively 15.52 cc. and
9 cc. daily average for a period of 18 consecutive months. The
scrub oak forest shows less actual variation than any other except
the flatwoods, this probably being related to the stunted character
of the oaks, their close thicket-like growth, and their habit of
retaining the dead leaves most of the winter or until fresh growth
starts. In striking contrast, the long-leaved pine forest shows
the most extreme variations in range of evaporation of any other
station.
*7
The contrast between the two long-leaved pine associations is
greatest
rate throughout the year than any other and averages 12.99 cc.
daily for the 18 months, thus taking the place next in order to the
mesophytic climax forest. The summer evaporation for the flat-
woods averages 13 . 24 cc. daily, comparable to that of the scrub
oaks and the pastured beech wood. The average winter rate is
1 . 17 cc. daily, being the lowest, and this is the case although this
1
more
p
turpentinin
37°
BOTANICAL GAZETTE
[may
xperiments
*
coefficient) were obtained and determined
method
confirm the statement
Although incom-
Fig. 10. — Chart showing relation of wilting coefficient and soil moisture of Leon
sand, and comparison with precipitation: AA, wilting coefficient; BB, range of soil
aporation
moisture from September to June; __, e _^« w wmmMJ , f(VW-1 . _ .
station during same period; R, curve of average monthly rainfall (in inches); R J ,
curve of rainfall during the period.
the wettest soil, not actual swamp, in the region. The wilting
coefficient of soil taken from the first 3 inches of the surface is
approximately 5 . 9, while the average percentage of the soil mois-
ture present during the year is 1 2 . 74 (fig. 10). Only once (in April),
i9i 7] GA NO— ECOLOGY OF FLORIDA 371
t
at the end of the spring drought, does the percentage of moisture
in the first 3 inches of soil fall lower than the wilting coefficient,
and then but slightly. The maximum amount is reached in late
January and early February, while a summer maximum is reached
in July, coinciding with the two periods of rainfall. The curve
of the range of the soil moisture agrees quite closely with that of
the average daily evaporation, which in this association therefore
has a direct relation to the soil moisture and the consequent
humidity of the atmosphere at the surface of the soil where
evaporation is actively occurring.
Considering the edaphic character of the flatwoods in expla-
nation of its position as determined by the evaporation averages,
the order of succession for upland forests as observed seems to
have a definite relation to the obtained rate of evaporation.
This tends to confirm the observation that in the coastal region
studied the present pines are pioneers making a temporary forest,
which, owing to present geological, topographical, and soil condi-
tions, may make but slow progress toward the ultimate climax, at
least over large areas. When once started, however, the climate
favors a rapid mesophytic, advance.
To the lectures and teaching of Dr. H. C. Cowles I am indebted
for my interest in this subject and for my point of view; to
Dr. G. D. Fuller for instructions concerning field work with
e vaporimeters ; and to Dr. J. M. Greenman for aid in identification
of various plants. Also I acknowledge the assistance of Professor
Jerome McNeill of Tallahassee, Florida, in the field work and
in securing the evaporation and soil moisture readings over an
extended time.
Richmond, Ind.
LITERATURE CITED
J
Circ. Bur.
Soils, U.S. Dept. Agric.
2. Briggs, L. T., and Shan
determination. U.S. Dept. Agric, Bur. Plant Ind. Bull. no. 230. 191 2.
Climatological Service Reports, District no. 2, South Atlantic and ea
Gulf states. U.S. Dept. Weather Bur. Service, 1912-1914.
I
372
BOTANICAL GAZETTE
[may
4. Fuller, G. D., Evaporation and plant succession. Bot. Gaz. 52:193-
208. ign.
5. Harper, R. M., A phytogeographical sketch of the Altamaha grit region
of the coastal plain of Georgia. Ann. N.Y. Acad. Sci. 17: 1907.
, Preliminary report on the peat deposits of Florida. 3d Ann.
6.
Report, Fla. State Geol. Surv. 1909-1910.
7
■, Geography and vegetation of northern Florida. 6th Ann. Report,
Fla. State Geol. Surv. pp. 163-431. 1914.
8. Lloyd, Tracy, Insular flora of Mississippi and Louisiana. Bull. Torr.
Bot. Club 28:61-101. pis. 8-11. 1 901.
9. Matson, G. G., and Clapp, F. G., A preliminary report on the geology of
Florida. 2d Ann. Report, Fla. State Geol. Sur. 1 908-1 909.
10. Sargent, C. S., Forests of the United States. 10th Census. Vol. 9.
1884.
11. Schimper, A. F. W., Plant geography. 1903.
12. Sellards, E. H., Some Florida lakes and lake basins. 3d Ann. Report,
Fla. State Geol. Surv. 1909-1910.
, Classification of the soils of Florida. 12th Ann. Report, Comm.
13
Agric. Florida. 19 13.
14. Wilder, H. J., Drake, J. A., Joxes, G. B., and Geib, W. B., Soil survey
of Leon County, Florida. Field Operations, Bur. Soils. 1906.
15. Williams, J. L., A view of west Florida. 1827.
r
PERMEABILITY OF CERTAIN PLANT MEMBRANES
TO WATER
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 230
F. E. Denny
(with TWO figures)
Introduction
In the exchange of material between the plant and its environ-
ment > 3 groups of substances may be considered important, namely,
water, gases, and salts. These enter the plant, pass from one
portion to another, and some of this material finally passes out
into the environment again. In this process a great many mem-
branes must be penetrated. The permeability of these membranes,
therefore, is a factor in this material exchange, determining in a
measure what substances may enter or leave the plant and at
what rate this entrance or exit can take place. For this reason
measurements of the permeability of plant membranes become
desirable. While much work has been done toward this end from
a qualitative standpoint, and while many indirect measurements
have been made, direct quantitative measurements in which the
results could be referred to known areas of membranes, under a
standard set of conditions, have been lacking.
This paper deals with an attempt to get quantitative data on
the permeability of certain plant membranes to water; to determine
what laws, if any, hold for the rate of penetration of water as
related (i) to temperature, (2) to direction of flow through mem-
branes, (3) to concentration of the bathing solutions, and (4) to
species of plant under consideration.
Membranes
Non-living membranes such as seed coats and the outer scale
of the onion bulb were used, as they were suitable for use with the
apparatus employed. The importance of non-living membranes
373I
(Botanical Gazette, vol. 63
374 BOTANICAL GAZETTE [may
must not be underestimated. That they perform great physiolog-
ical functions is coming to be recognized more and more as our
knowledge of them increases.
The cell wall may be thought of as a non-living membrane, and
its functional importance is emphasized by the work of Hansteen-
Cranner (16), in which it is indicated that the antagonism of
Ca" for Mg" in root toxicity, the action of Ca" in increasing
transpiration and decreasing absorption, and the action of K" in
decreasing transpiration and increasing absorption, is due funda-
mentally to the effect of these ions upon the cell wall. The impor-
tance ascribed by Wachter (30) to the cuticle and cork of the
outer layers- of the beet in preventing the loss of sugar also may
be pointed out. Other investigators (4, 10) have shown that the
non-living coat plays a dominant role in seeds, the coat character
being an important factor in determining the respiration, water
intake, entrance of toxic materials, delay in germination, longevity,
protection from leaching of stored materials, and from mechanical
injury, etc.
membranes
in itself, and it was hoped that results so obtained would throw
light upon the problem of the permeability of plant membranes
in general. In this connection we quote Pfeffer (24): "the
will first have to deal with
mental
perhaps in
make clear processes taking place in th
living semipermeable plant membrane
r Brown (5) in the barley grain, and h
7?
in 1907 by Brown (5) in the barley
Worley (6) measured its permeability to water. Schroeder
(27) reported a similar membrane in the wheat grain. Gola (13)
found such membranes in the seeds of a great many different
species.
measure
of the membranes to water. Shull (28) found that the seed coat
permeable to certain substances, and pointed
r antage this membrane had for experimental
sem
purposes, in that it could be remo\
meability characters studied directly, without other structures
becoming factors in the experiment. He constructed an osmometer
^
f
1917]
DENN Y—PERMEA BILI T I
375
in which a portion of the seed coat was used as the membrane, and
made preliminary measurements on the rate of penetration of
water. The problem of getting quantitative measurements of
the permeability of various plant membranes was then undertaken
by the writer with the results here reported.
The rate of penetration of water through membranes was
measured with an osmometer of the design shown in figs. 1 and 2.
A, B, and C are hard rubber discs, 3 . 5 cm. in diameter and 2 mm.
in thickness. Brass discs also were used, but are not suitable for
Fig. r. — Photograph of osmometer: explanation in text
use with salt solutions. In the centers of A and B at K is a hole
of known diameter. Between A and B and over this hole the
membrane to be studied is placed ; thus the area of the membrane
used can be calculated. D is a hard glass cylinder with ground
edges fitting snugly against the hard rubber discs. Soft rubber
gaskets are interposed between the glass cylinder and the discs
made
admitt
The
latter is tilled with distilled water until water appears in the hori-
zontal capillary tube. The position of the meniscus in G may be
nf tV»f <;tonrork in F. G is a
means
ro cm.
capillary tube with about 10
capillary bore of approximately i mm. Scale divisions on G were
376
BOTANICAL GAZETTE
[may
i
calibrated by weighing with mercury. One scale division on G
0.000337 gm. of water at 25 C. The whole apparatus is then
immersed in a vessel containing a solution of cane sugar or sodium
chloride and the vessel placed in a water bath regulated to constant
temperature. The osmotic force of the bathing solution pulls
water through the membrane from the internal chamber, and this
causes the meniscus in the capillary tube to recede. By successive
j ' * 1 ( 1 1 i n
//////
Fig. 2.— Drawing of osmometer: explanation in text
readings of the position of the meniscus in G at various intervals
of time the ru
be determined.
movement through the membrane can
As water passes through the membrane, it has a tendency to
dilute the bathing solution at K. This tendency is overcome by a
stirrer whirling in front of the membrane at K which keeps the
concentration constant there. The amount of water passing into
the bathing solution is so small as compared with the large volume
of the latter that the concentration of the solution exerting the
osmotic pull is maintained constant.
1917]
DEXX I —PERM E A BILI T 1
r
377
I
At the end of an experiment it is possible to record the quantity
of water passing through a known area of membrane, in a known
interval of time, at a constant known temperature, and under the
constant osmotic
pull of a solution whose osmotic pressure in
atmospheres is known. This gives a measure of the permeability
of the membrane under the conditions of the experiment.
The sources of error and the precautions taken were as follows :
Temperature
; immersed i
— It was found that when the apparatus
minutes. An interval of at least 10 minutes was
allowed before readings were begun.
The temperature of the
bathing solution was constant to =±=o?i C. The effect of the
possible deviation of the temperature of the internal liquid upon
the readings of the meniscus in the side arm was calculated. 1 The
volume of the osmometer is 4421 .13 cu. mm. Assuming it filled
with water at 4 C, then changes in temperature of o?i show the
relation between temperature errors and scale division of the
osmometer as indicated in table I.
Temperature
TABLE I
Volume error
(in mg.) of water
i5°*o?i
2 5 °*o?i
35° *=o? 1
45° ±0° 1
0.01326
0.17665
0.18525
0.30764
0.37212
Scale division
value (in mg.)
of water
Error of readings
in scale divisions
II
arm
scale division. Temperature deviation therefore introduced no
error resulted.
temperature
Variation in membranes.— It was early found that there was
a lar
same species.
permeability of different
membran
but only with itself under the various conditions of the experiment.
1 Calculated from data taken from Smithsonian tables, Smithsonian Misc.
Coll. 63: no. 6.
378 * BOTANICAL GAZETTE [may
The permeability of the same individual membrane was measured
under the different conditions studied, therefore, and the same set
of observations made with a number of other membranes of the
same species. In some cases it was possible to allow the same
membrane to remain in the osmometer during a whole series of
readings. When it was necessary to remove the membrane from
the osmometer, care was taken in replacing it that the same portion
of the membrane was used in the next reading.
Constancy of semi permeability. — When a membrane gave con-
stant rates for i hour, readings being taken at intervals of 10
minutes, it was assumed that its permeability to salt or sugar had
not changed during the experiment, or at any rate that any change
in permeability that had occurred did not affect the readings taken.
No serious attempt was made to determine the completeness of
semipermeability. Preliminary experiments indicated that the
membranes were slightly permeable to sodium chloride, but a
passage of cane sugar through the membrane was not detected.
Conductivity measurements are to be made to determine the
permeability of these membranes to salts, and these results will
be reported in a later paper.
Preparation of solutions.— C&ne sugar solutions were prepared
in accordance with tables given by Find lay (ii), rock candy
being used. Sodium chloride was made up on the volume molec-
ular basis and its osmotic pressure figured from the data given
by Renxer (25).
Capillary tube errors. — Although according to the law of Poise-
uille the flow of water through capillary tubes is affected by
temperature, it is not believed that this was a factor in these
experiments. In Poiseuille's experiments the liquid was sub-
jected to a head of pressure and flowed through the capillary tube
with rapidity, whereas in these experiments there was no hydro-
static pressure applied and the rate of movement through the tube
was very slow. According to Barker (3), when water is the liquid
in question this law applies only to tubes with less than 0.5 mm.
diameter of capillary; while the capillary used in these experiments
was 1 mm. It is not believed that the results obtained are affected
by the influence of temperature on the flow of water through the
capillary tube of the apparatus.
1917]
DENN Y—PERMEA BILI T I
379
precautions
membranes
water before being used for experimental purposes. The distilled
water used inside the osmometer was previously boiled to drive
off dissolved gases.
made to determine that no leakage
In filling the osmometer care
was occurring in the apparatus,
was taken to drive out all air bubbles from the internal portion
of the apparatus. Special pains were taken to see that no air
bubbles were lodged on the membrane.
Effect of temperature
Membranes of the seed of Arachis hypogaea
measurement
of water at the temperatures
at the various temperatures,
After being measured
1
2
3
4
5
6
7
8
9
10
11
12
TABLE II
Effect of temperature upon permeability of seed coat (membram
of Arachis hypogaea)
Number
Osmotic ' ^ ater (* n m &-) passing through 19. 635 sq. mm. of membrane per hour
pressure at
25°C.
2765
a
a
41.48
a
5.2C
II .OI
22.93
15.2 c
25.2 c
35. oC
45. oC
18.59
38.08
u
u
13.82
16.51
33 02
42.19
37-91
a
u
u
13-45
15-41
28.32
53 12
69.07
59 03
21
2 S
24 79
From left to right, the figures are readings obtained from the same individual membrane at different
temperatures; each line represents a different membrane.
against a previous temperature to be certain of constant behavior.
In transferring from one temperature to another the membrane
was not removed from the osmometer, so that the results indicated
in table II show a comparison of the rates indicated by the same
membrane at different temperatures. When the bathing solution
m
also changed, and a correction was made for this change in osmotic
3 8o
BOTANICAL GAZETTE
[may
pressure of the bathing solution due to changes in temperature.
The actual osmotic pressure of the solution at the temperature used
was calculated on the basis of proportionality between osmotic
pressure and absolute temperature. The observed rate was
corrected on the basis that the rate was proportional to the pull
applied, which will be shown later to be the case for solutions of
sodium chloride. When cane sugar was used as the bathing
solution the observed rate was not corrected, because proportion-
ality between rate and pull applied does not exist with such
solutions.
TABLE III
Value of Q
10
5 .2-i5?2C
i5-2-25°2C.
25-2-35°oC
35 • 0-45°° C.
1.688
1.564
1-374
1-332
i.
1
661
I .
528
1 339
« i-39°
i.
716
I.
512
1.258
1-259
i.
609
I.
546
1. 206
1.364
i
637
I
487
1-433
i-3<>5
i
53o
I
507
1.448
1 .411
i
579
I
610
1.388
1.204
1.608
I
449
1. 298
1.384
Average, 1.628
1525
1-343
- 1.344
TABLE IV
Effect of temperature upon permeability of seed coat (membranes
of Arachis hypogaea)
Number
I
2
3
4
5
Osmotic pressure
of cane sugar
solution at
25
°C.
21.25
u
u
u
Water (inmg.) passing through 19.635 sq. mm. of membrane per hour
3?6C
7-98
13 12
II .64
6-39
14-55
I3?6C
13
21
19
IO
23
69
II
40
27
39
2 3 ?6C
20.54
30.07
28.92
I4-38
35 09
33?6C
26.81
42.21
38.79
19 5 1
46.89
may estimate the coefficient
in
Q I0 . Experi-
which
bathing medium instead of sodium chloride. The results with
cane sugar are given in table IV. The figures in table IV give
1917]
DENN Y—PERMEA BILI T Y
3«i
coefficients for io° C. as recorded in table V. These data were not
corrected for change in osmotic pressure due to change in tem-
perature, because, as will be shown later, the rate is not exactly
proportional to the pull applied. But that this correction would
TABLE V
Value of Q 10
3.6-i 3 ?6C.
I3.6-23?6C.
23.&-33?6C.
I. 716
1 .610
I.667
1 .607
1 .607
1. 541
1.424
1.492
1.400
1.500
I-J05
I 403
1-342
1. 357
1-336
Average, 1.641
1.463
1348
be a small one and that it would not affect the general results, is
indicated by the following results obtained when a correction is
figured on the assumption that the rate is proportional to the pull .
Making this correction, the first column of table IV, showing values
°f Qio, becomes:
1.649
1 547
1 .604
*
1-545
1 -546
In addition to
Average, 1 . 578
preliminary
measurements of 6 other membranes. While the conditions of the
experiment were not so accurately controlled, the
coefficients obtained were as follows :
average
Approximately 5 to 15 Q
10
u
Temp
sffi>
=1.617
15 to 25 Q I0 =i.47o
25 to 35 Q IO =i422
The effect of temperature upon a
1 much used to obtain informat
chemical or oh vsical . Generally
►peaking
(Qio =2 to 3), but the effect of
^82 BOTANICAL GAZETTE [may
o
temperature upon the process of diffusion is such that Q I0 is approx-
imately 1.3. Applying the results of these experiments to this
case it is found that the coefficient obtained does not correspond
with either the van't Hoff coefficient or the diffusion coefficient.
Measurements of the permeability of membranes made heretofore
have shown in general a temperature coefficient approximating
that of the van't Hoff law, but there is no evidence in these experi-
■
ments that in the passage of water through the seed coat of the
peanut chemical processes are exclusively involved. Apparently
also the effect of temperature is not merely upon the rate of diffusion
of water. Probably we are not justified in using the numerical
coefficients obtained to form any conclusion as to the nature of the
process by which water passes through the peanut membrane.
Comparison with temperature coefficients obtained by others. —
Krabbe (19) measured the effect of temperature upon the per-
meability of the living cells of cylinders of pith of Helianthus annuus
and pieces of roots of Vicia Faba, etc. As criteria he took the rate
of increase in length of pieces of plasmolysed tissue, allowed to
absorb water at temperatures in vicinity of o° and 20 C, and the
length of time for plasmolysis to occur at these temperatures. He
found that the velocity of water movement increased 3-5 times
when the temperature was increased 20 C. (Q J0 approximately
2.0-2.5). He believed that this high coefficient indicated that
purely physical forces were not operative, but that it was due to
a specific property of living protoplasm.
Rysselberghe (26) investigated the effect of temperature upon
the permeability of the living protoplasm, using pith cells of Sam-
bncus nigra, lower epidermal cells of Tradescantia, and filaments of
Spirogyra. He made use of 3 methods: the rate of shortening
of a tissue in a plasmolysing solution at different temperatures,
the rate of elongation of plasmolysed tissue in water at different
temperatures, and the rate of plasmolysis of a tissue under micro-
scopic observation. His general results are as follows:
Temperature 06 12 16 20 25 3°
Comparative rate ....i 2 4.5 6 7 7.5 8
This gives an average value for Q I0 from o°-30° of 2.0. Ryssel-
berghe does not agree with Krabbe that this high coefficient
necessarily indicated the special activity of vital matter.
1917]
DEXX V—PERME. 1 BIUTY
38
"J
Brown and Worley (6) determined the speed of intake of
water by barley grains immersed in water at different temperatures.
Their results gave a temperature coefficient of 1.8
1.9
Since
this approached closely the van't Hoff coefficient (2-3) for the
effect of temperature on the rate of chemical reaction, they con-
sidered that chemical processes were involved in the penetration
of water through the semipermeable membrane of the barley grain.
This chemical reaction, according to their view, took place in the
water itself, that the effect of temperature was to split the larger
aggregates of water into simpler ones, and that only these simpler
molecules were transmitted by the differential septum. This was
offered as evidence in favor of the hydrone conception of
Armstrong (i) as to the composition of water.
Pfeffer (24) measured the rate of water movement across the
copper ferrocyanide membrane at different temperatures with the
following results:
Temperature
In stream per hour
7?i
5.9 mm.
I7?6
9 4 "
32?5
13-3 "
; give values of Q I0
as follows:
J.i-
-17-6,
Qio
= 1558
17.6-
-32-S,
Qio
= 1 .266
The writer's observed values are in fair agreement with these
figures. For purposes of comparison, a summary is given in table
VI.
will be noted from
TABLE VI
Observer
Krabbe
Rysselberghe
Brown and Worley
Pfeffer
The writer. . . .
Nature of membrane studied
Living pith cells of
H el i ant has
Living cells
Semipermeable mem-
brane of barley seed
Copper ferrocyanide . . .
Seed coat of Arachis
hypogaea
Temperature range
0-4 to 20-26
O to 30°
3.8 to 34-6
7 1 to 32?5
3-6 to 45°
Q
1©
2.0 to 2.5
2.0
1.9 to 1.8
1.558 to 1.266
1.641 to 1.343
observed.
membrane
peanut
3 84 . BO TA MCA L GA ZE TTE [may
should be expected to give similar results, while the similarity of
results given by the copper ferrocyanide membrane and peanut
should not be expected. We may note, however, a parallel between
the method of observation employed and the coefficient obtained.
The first 3 observers studied the permeability of the membrane
indirectly, other structures such as cell contents and seed contents
being present. In the last two cases the membrane was measured
directly, without other structures being factors in the rates observed.
It is questionable to what extent results obtained by the indirect
method may be referred to the membrane alone. There is the
possibility that the temperature effect may have been, not upon
the membrane merely, or upon the water exclusively, but also upon
the cell contents or seed contents. The latter effect may have
contributed to the total results from which the coefficients were
calculated. The chemical reaction indicated by the coefficient
2-3 may have taken place in that phase of the system that was
internal to the membrane studied.
In these experiments the temperature may have exerted an
effect on the water, but if so the temperature coefficient does not
indicate that this was related to a chemical reaction. There is no
evidence of a temperature action in splitting the larger water
aggregates into simpler hydrone molecules as found by Brown and
Worley with the semipermeable membrane of the barley grain.
Tendency of temperature coefficients to fall in value with increased
temperatures. — An inspection of the temperature coefficients ob-
tained in these experiments shows that the coefficients are higher
at the lower temperatures and lower at the higher temperatures.
great many
KANITZ (18) noted a number
this tendency. Snyder (29)
some
Q I0 , and Cohen-
dine to the van't Hoff
values of Q I0 are not constants and that the velocity is not an
exponential function of the temperature. Table VII indicates the
general tendency of Q I0 for different processes. Falling values
Q
10
measurements made
matter, (b) with non-living matter, (c) with a physical
»
'
1917]
DENN I —PERMEA BILI T V
385
process, and (d) with a chemical process. These figures also
em
averaged for a large interval of temperature, but that the range
of the values of Q I0 for each temperature interval should be shown
for which experimental data are available.
TABLE VII
Rysselberghe's
results with living
protoplasm
Results obtained with
non-living plant
membranes
Vapor pressure
of water at various
TEMPERATURES j
Remsen and Reid's
results with hydrolysis
of nitro-benzamide*
Tempera-
ture
Qx*
Tempera-
ture
Q«
Tempera-
ture
Q»
Tempera-
ture
Q«
o-6°
6-12
12-16
16—20
20-25
25-30
3-2
3-8
2.0
1-5
I. I
I. I
5-2-i5?2
15.2-25.2
25.2-35.0
35.0-45.0
1.628
1-525
1-343
1-344
5-15
15-25
25-35
40-50
1 943
I • 854
1.776
i.°75
60-70°
70-80
80-90
90-100
I.84
1.72
1 65
1 59
* From data given by Snyder (20, p. 169).
itions of permeability of membranes to vapor pressure of wate\
experiments of Brown and Worley (6) showed that Q
10
pproximated in numerical
rater at those temperatu:
From table VII it will be noted
that similar results were not obtained with the peanut membrane;
that while the coefficient of permeability rates and vapor pressure
are not equal, they both show the same tendency to fall in value
temperatures
may
coefficient
coefficient
flow through capillary
According to the
law of Poiseuille, as reported by Krabbe (19), the quantity of
water flowing through a p-Irss tube increases from 1 to 1+0 0336703
/-ho. 00022
grade (Kr,
rabbe iq, p. 477). This would make the coefficient for
10 rise in temperature about i .358. Since this law applies only to
minimum
and since the temperature coefficients obtained in these experiments
are not constants but vary with the temperature, it is not believed
3 86
BOTANICAL GAZETTE
[may
that the results obtained indicate that the passage of water through
the membrane is analogous to the passage of water through capillary
tubes.
previous
— When the per-
meability of a membrane is measured at one temperature and the
membrane then transferred to another temperature, the question
is raised as to whether or not there is any "after effect" of the
temperature
determine this uoint m
fitted into 2 osmometers and a measurement was made of the
permeability of each membrane. One osmometer was then placed
in a beaker of water in an ice chest at 2.5 C, and the other in an
1
oven at 46 C. The next day the two were again placed in the
original osmotic solution at the original temperature and readings
again taken. The results obtained are given in table VIII. No
after effect of a previous temperature, or hysteresis, was observed
at the temperatures used in these experiments.
TABLE VIII
Intervals of 10 minutes
25° C.
First membrane
First
27 spaces
29 "
28 "
29 "
*
20 spaces*
29 "
29
Second
Third
Fourth
Fifth
Second membr;
First . .
Second
Third .
Fourth
Fifth . .
23 spaces
23 u
24 a
23 spaces f
24
22
23
a
* After 14 hours at 2?5 C.
t After 15 hours at 45 C.
Rate as affected by direction of flow of water through membra)
A peanut seed coat membrane was placed in an osmometer j
measurement made of the rate at which water nassed throu
from the osmometer
position
surface being turned toward the
1917]
DENN Y—PERMEA BILI T Y
387
osmometer. The latter was then placed again in the
made
IX
more permeable
The peanut membrane
other, and the favorable direction is from the outside toward the
inside.
TABLE IX
Rate as affected by direction of flow of water through membrane
of Arachis hypogaea
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Diameter
of HOLE
OsMo-rrc
PRESSURE
Water (in mg.) passing through membrane per hour
In
Out
8 mm
u
u
a
a
u
tt
u
u
u
u
u
a
tt
5
67
u
u
IOO
u
25
48
tt
tt
139-52
137. 54
124. 26
9925
396.21
236.88
164.38
36.89
30 55
In
Out
95
87
93
43
207
158
121
20
27
70
79
35
44
49
92
20
09
21
94
27
82
70
17
87
65
75
06
Percentage
decrease
from in
to out
135 l6
III. 18
98.86
402.67
224.80
202.32
30.04
38.02
106. II
III. 82
53-77
63.69
71.88
90.91
84.58
205.97
146. 12
127 59
2470
26.98
44 -5o
32
3i
25
56
49
34
32
32
20
33
38
33
29
3i
. "In" means direction outside of seed toward inside; "out" means direction inside of seed toward
outside.
Measurements with the seed coats of Prunus Amygdalus
dulcis gave the following results:
Rate in
Rate out
Rate in
48 . s mg. per hour
42.6 " u u
48.5 * " U
Rate out = 40 . 4
a
a
u
Measurements made
coat of Dioon edule did not indicate any observable difference in the
rate of penetration in opposite directions. This difference in the
differenc
types of membranes
posed of two or more
The peanut and almond seed coats
different physical and chemical nature on opposite sides; such is
3 88
BOTANICAL GAZETTE
[may
not the case with onion and cycad membranes. The differences in
rate in opposite directions through a membrane have long been
known to workers with animal membranes. Matteucci and
Cima (21) in 1845 observed it with the skin of the frog and eel.
Cohnheim (9), according to Hamburger, ascribed the same
phenomenon to the living action of the intestinal membrane.
Hamburger (14) showed that this behavior was not restricted to
living membranes, but that non-living animal membranes gave
similar results; in fact, he prepared artificial membranes from
parchment with layers of collodion, chromgelatin, and chromal-
bumen that were more permeable in one direction than in the
other. He ascribes this to the "double" nature of the membrane,
and the writer's results offer evidence in favor of Hamburger's
interpretation. If this difference in rate is due to the presence of
double membranes of different nature, or to differences in surface
on opposite sides, may not the plant cell itself show a difference in
permeability in opposite directions, since such a system of double
membranes is represented by the cell wall and ectoplast ?
Rate as related to the concentration of the external solution.
Solutions of different osmotic pressures were used as the external
solution in order to determine whether or not the rate of water
table x
Relation between osmotic pressure applied and
rate (sodium chloride solution)
I
2
3
4
5
6
7
8
Number
ter (in mg.) passing through membrane
hour in atmospheres of osmotic pressure
13-82
27.65
22-53
21.96
28.53
35 37
3423
35 94
4437
44.37
28.09
5818
56.48
68.93
41.48
88.0
67.89
66.75
4279
82.15
102.69
88.99
movement was proportional to the pull applied. Two solutions
were used, sodium chloride and cane sugar. The results with
sodium chloride are shown in table X. A comparison of the
I9i/]
DEXX I —PERMEA BILI T 1 '
389
'
osmotic pressure and rates from the data in table X is given in
table XI.
Ratio of
pressures
2765:13-82
2 .OOO
2 .000
2 .000
2 .OOO
Ratio of rates
I.969
2.020
1 .980
I.949
TABLE XI
Ratio of
pressures
41.48:27.45
I.500
I.500
I.500
1.500
Ratio of rates
I -S30
I.504
1. 471
1. 412
Ratio of
pressures
41.48:13.84
3.000
3.000
3.000
3.000
Ratio oi ratct
3.040
3.029
2.977
TABLE XII
1
Relation between osmotic pressure
AND RATE (CAXE SUGAR SOLUTION)
I
2
3
4
5
6
7
8
9
10
11
12
13
14
16
n
18
J 9
Xumber
Water (in mg.) passing through membrane in atmospheres of osmotic pressure
5 15
10.30
1562
21.25
29.22
48.00
9.70
8.55
8.16
7.70
14.09
14-73
II. 81
12.83
IO.84
13.69
5-53
6.84
11.98
23-39
29.44
21 . 11
18.25
16.83
13-35
27.04
25-84
19.40
23 -45
21. 11
24-53
9.69
11.72
23.96
23.10
29.44
3765
27.09
24-53
24- 25
18.17
36.62
3526
23.96
31.66
2795
3i 95
11 .98
13.69
29.66
28.07
33-66
35-37
3i 95
28.43
21 .96
45.i8
42.79
28.24
35-37
33 66
39 36
13.69
16.54
36.97
34.80
* ■■
4107
50 49
4 75
53 OS
63 -32
84.72
A comparison of the ratios of pressure and the ratios of the
rates indicated in table XII is given in table XIII.
When the ratios of pressure applied were 2.000, 1.515. 1 36°>
and 1.642, the average ratio of rates observed was 1 .888, 1297,
1. an, and 1.285 respectively. It will be seen that the rate of
water penetration is nearly proportional to the pull applied when
sodium chloride is used, but that when cane sugar is used as the
external solution, the rate is not proportional to the pull, but the
39°
BOTANICAL GAZETTE
[may
coefficient falls off with the higher concentrations. It is believed
that this lowering of the rate is due to the increasing viscosity of
more concentrated sugar solutions.
TABLE XIII
Ratios of rates
5.15:10.30
10.30:15.62
2.170
1-259
I. 144
2-133
1.279
I-305
2.063
1.284
I.302
1.734
1-344
I. 172
1.919
1. 441
I. 209
1.756
1. 361
1-234
1.634
1-354
I. 214
1.82s
1.364
I. 179
1.947
1.235
I. 117
1.792
i-35i
I.204
1.753
1-325
x.233
1. 712
1 .302
1 143
2.000
1235
1.208
u
1. 168
1.246
a
MM
1.238
1.249
*
X.2I<
1
20.22:48.0
I. 292
1.254
1.308
Average, 1 . 888
1.297
1. 211
1-285
It was found that it was not possible to increase the concentra-
tion of the solutions on opposite sides of a membrane by an equal
amount on each side without changing the rate at which water
membrane
followin
osmometer
having a known osmotic
movement
Then the
osmotic Dressure was increased on each side of the membrane
amount
XIII
Thus,
although the effective osmotic pressure exerting an influence upon
water movement was practically the same, the rate of water
same
much less. With
same
movement was not the
membrane the same osmotic pull does not give the same rate, but
the rate depends upon the distribution of the concentration on
opposite sides of the membrane. When the concentration of
the external solution was kept constant and the concentration
of the internal Qnliitinn waQ \7*\r\(±A tfiA r^cnltc mvpn in table XIV
1
1917]
DENN Y—PERMEA BILI T Y
391
were obtained with sodium chloride solutions. From these data
the writer has not been able to formulate any mathematical relation
between differences in concentration on opposite sides of the
membrane and the rate of water movement through it. Another
TABLE XIII
Rate of water movement as related to differences in concentration of
solutions on opposite sides of membrane
Membrane
Solution
Osmotic pressure
of external
solution
Osmotic pressure
of internal
solution
1
Effective osmotic
pressure
Rate per hour
First
U
Second
a
» • .• • . •
Third
Fourth
u
NaCl
a
a
Sugar
u
a
18.43
36.86
13-82
27.65
, IO.30
21.25
IO.30
21.25
O
18.43
O
13.82
O
IO.30
O
IO.30
18.43
18.43
13.82
13.83
10.30
1095
10.30
IO-95
48.29
35-94
41.07
• 2396
20.54
10.84
29.09
I5-63
Fall
TABLE XIV
RATE OF WATER MOVEMENT WHEN CONCENTRA-
TION OF INTERNAL SOLUTION WAS INCREASED
Osmotic pres-
sure OF EXTER-
NAL SOLUTION
46. IO. .
a
u
a
u
u
a
Osmotic pres-
sure of inter-
nal SOLUTION
O
4.61
9. 22
13.82
18.43
23 05
27.65
Water (in mg.) passing through
membrane per hour
First
67.74
Second
49.54
45-21
45-49
3943
3939
3299
26.96
2427
22.92
18.86
12.13
10. 11
61.67
set of readings was taken in which cane sugar solutions were used.
XV
between concentration and rate is complex.
From
&
2T
of the internal solution; (2) that equal osmotic differences do not
necessarily produce equal rates; and (3) that no mathematical
relation has been noted between the concentration on opposite
392
BOTANICAL GAZETTE
[may
ides and the rate of water movement through the membrane,
rhis emphasizes the caution that must be used in plasmolytic
xperiments on the rate of water movement through a membrane.
is deals with solutions of different concentrations on
Plasmoly
membrane. The concentration of only one of
>lysing solution , is known. In such
the solutions, the plasmoly sing
experiments the internal concentration of the cells of plant or seed
is not known and is subject to change, that is, to variations in
pulling power. Results should not be referred to changes in the
permeability of the membrane alone until it has been found that
the internal concentration has remained constant during the
experiment (it is to be understood that this statement is intended
to apply to rate of water movement and not to the final equilibrium
attained by the two solutions).
TABLE XV
Rate of water movement as related to differences in con-
centration of solutions on opposite sides of membrane
Osmotic pres- Osmotic pres-
sure OF EXTER- SURE OF INTER-
NAL SOLUTION NAL SOLUTION
73-69
48.O.
21.25
IO.3O
73-69
73 69
48.O.
21.25
o
o
o
o
10
21
IO
IO
30
30
30
Effective
OSMOTIC
PRESSURE
73-
48.
69
21.
25
10
63
30
39
52
42
37
.70
10
95
Water (in mg.) passing
through membrane
PER HOUR
41.07
37 65
27.38
13-59
21.39
958
17. 11
6.84
Second
37 65
34.23
21.39
17. 11
20.54
11. 13
16.26
8.56
Comparison of permeability of membranes of different species
Membranes from different species showed large differences in
permeability, as indicated by table XVI. Equal areas (19.635
mm.) of membranes were measured
sodium
osmotic
external
will be seen that membranes
species and different membranes of the same species show large
differences in permeability. The causes of these differences in the
1917]
DENN Y—PERMEA BILI T I
393
rate of penetration will be dealt with in a later paper. It may be
stated here, however, that thickness of membrane is not the limiting
factor. The
thickest is th
memb
is that of Cucurbit a, and the
TABLE XVI
Relative permeability of various membranes
Membrane
Water (in
mg.) passing
through
per hour
Citrus grandis
u
it
a
u
a
Cucurbita Pepo
« u
u
it
a
tt
u
maxima
a
a
Xanthium pennsylvanicum
a
a
a
u
u
a
* *
Juglans regia
« a
Allium Cepa
Membrane
Allium Cepa
..
a
a
u
Prunus Amygdalus dulcis
u
u
a
u
u
a
u
u
u
u
u
Arachis hypogaea
u a
u
u
u
u
u
a
u
u
a
Dioon edule
Water (in
mg.) passing
through
per hour
39-2
12.9
12.3
31.2
22.4
120.0
144.0
72.0
86.0
60.0
72.0
72.0
328.0
53° -o
564.0
710.0
528.0
672.0
584.0
777-5
Structures of membrane used
The layers of tissue represented in the ripened seed coat of the
various species and their origin have not been accurately determined
by an examination of successive stages of the development of the
seed. A study of the histology of the seeds of Cucurbita has been
made by Barber (2), of Prunus Amygdalus by Pechoutre (23), of
Xanthium by Haxausek (15), of the Leguminosae by Pammel (22),
and of the seed coats of various species in many families by Lonay
(20), Brandza (7), Guignard (w), and Harz (17). From an
examination of sections of the membranes used, and from a
comparison made with the reports of these investigators, it is
believed that the following structures are involved in these mem-
branes: (1) an outer integument, a much compressed and hardly
394 BOTANICAL GAZETTE [may
distinguishable inner integument and nucellus, and a single layer of
endosperm in Arachis hypogaea and Prunus Amygdalus dulcis; (2)
a single integument and a layer of endosperm in Xanthium penn-
sylvanicum and Juglans regia; and (3) a portion of the integument,
a layer of perisperm, and a layer of endosperm in Cucurbita Pepo
and C. maxima. Details of the structure of these membranes, and
a microchemical and chemical study of their composition will be
given in a later paper.
Summary
1. Quantitative measurements were made of the permea
ipermeable
expenmen
2. The apparatus and method employed had the following
advantages over osmometers ordinarily employed: (1) the passage
gm
membrane
be calculated; (3)
the concentration of the solution exerting the osmotic pressure
could be kept constant.
3. The effect of temperature upon the permeability to water
of the seed coat of Arachis hypogaea was measured and the tern-
1
perature coefficients for io° rise in temperature were obtained.
An average coefficient was not calculated. Since the temperature
coefficients
with
average coefficient is without significance.
coefficient
coefficient
chemical
are exclusively involved in the passage of water through the
membrane
temperature coefficients showed high
temperatures and lower values at higher temperatures, and this
is in agreement with the behavior of temperature coefficients in
other processes.
6. A comparison is made with the temperature coefficients
obtained in the permeability experiments of (1) Krabbe with
living membranes, (2) Rysselberghe with liviner membranes, (3)
1917] DENNY— PERMEABILITY 395
*
Brown and Worley with non-living seed coat membranes, (4)
Pfeffer with copper ferrocyanide membrane.
7. No hysteresis or after effect of a previous temperature was
observed.
8. It was found that the seed coats of peanut and almond
showed a difference in permeability to water in opposite directions
through the membrane, the faster rate being from the external
toward the internal portion of the seed.
9. When distilled water was placed on one side of the membrane,
the rate of water movement was proportional to the osmotic
pressure applied upon the other side, when sodium chloride solutions
were used; but this proportionality did not exist when cane sugar
solutions were used.
10. When solutions of varying concentrations were placed on
opposite sides of the membrane, it was found that the relation
between rate and concentration difference was complex, and that
in general equal osmotic differences do not necessarily produce
equal rates; the rate is greatly affected by changes in the con-
centration of the internal solution; no mathematical relation was
noted between the concentration on opposite sides and the rate
through the membrane. The bearing of these
movement
facts upon plasmolytic experiments based on rate of water move-
membran
11. A comparison of the permeability of several plant mem-
branes under similar conditions was made, large differences
appearing.
William
Crocker for suggesting the problem and rendering valuable
assistance during the course of the experiments.
142 South Anderson Street
Los Angeles, Cal.
LITERATURE CITED
1. Armstrong, Henry E., Hydrolysis, hydrolation, and hydronation as the
determinants of the properties of aqueous solutions. Proc. Roy. Soc.
London A. 81:80-95. 1908.
Barber, Kate G., Comparative histology of fruit and seeds of certain
species of Cucurbitaceae. Bot. Gaz. 47: 263-31°-
009
396 BOTANICAL GAZETTE [may
3. Barker, Geo. F., Textbook of physics.
4. Becquerel, Paul, Recherche sur la vie latent de la graine. Ann. Sci.
Nat. Bot. IX. 5:193-320. 1907.
5. Brown, A. J., On the existence of a semipermeable membrane inclosing
the seeds of some of the Gramineae. Ann. Botany 21:79-87. 1907.
6. BROWN, A. J., and Worley, 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.
7. Brandza, M., Developpement des teguments de la graine. Rev. Gen. Bot.
3:1-32, 71-84, 105-126, 150-163, 229-240. 1891.
8. Cohen-Stuart, C. P., A study of temperature coefficients and van't
HofiPs rule. Konn. Akad. Wetens. Amsterdam. Proc. Sec. Sci. 14:1159-
1172. 1912.
9. Cohnheim, O., Dber die Resorption im Dunndarm und der Bauchhohle.
Zeitschs. Biol. 37:443-480. 1908.
10. Crocker, Wm., Role of seed coats in delayed germination. Bot. Gaz.
42:265-291. 1906.
11. Findlay, Alex, Osmotic pressure. Longmans, Green, & Co. 1913-
12. Guignard, L., Recherches sur le developpement de la graine. Rev. Gen.
Bot. 7:1-14, 21-34, 57-66, 97-106, 141-153, 205-214, 241-250, 282-296,
303-311. 1893.
13. Gola, G., Richerche suila biologia e sulla fisiologia dei semi a tegumento
impermeabiles. Mem. Ace. Reale Sci. Torino II. 55:237-270. i9°5-
14. Hamburger, H. J., Permeabilitat von Membranen in zwei entgegen-
gesetzten Richtungen. Biochem. Zeitschr. 11:443-480. 1908.
15- Hanausek, T. F., Die " Kohleschicht " im Perikarp der Kompositen.
Sitzber. Kais. Akad. Wien I. 116:3-32. 1907.
16. Hansteen-Craxner, B., t)ber das Verhalten des Kulturpflanzen zu der
Boden Salzen. Jahrb. Wiss. Bot. 53:553-599. 1913-19*4-
17. Harz, C. O., Landwirthschaftliche Samenkunde. Berlin. 1885.
18. Kanttz, Aristides, Temperatur und Lebensvorgange. 191 5.
19. Krabbe, G., Uber den Einfluss der Temperatur auf die osmotischen Pro-
cesse lebender Zellen. Jahrb. Wiss. Bot. 29:441-498. 1896.
20. Loxay, H., L'Anatomie des teguments seminaux. Arch. Inst. Bot. Univ.
Liege 3 and 4:1-142. 1904.
21. Matteucci, Ch., and Cima, A., Memoire sur Pendosmose. Ann. Chim.
et Phys. 13:63-86. 1845.
22. Pammel, L. H., Anatomical characters of Leguminosae, chiefly genera of
Gray's Manual. Trans. Acad. Sci. St. Louis 9:91-274. 1899.
23. Pechoutre, F., Contribution a Tetude du developpement de Povule et de
la graine des Rosacees. Ann. Sci. Nat. Bot. 16:1-158. 1902.
24. Pfeffer, W., Osmotische Untersuchungen. 1877.
1917] DENNY— PERMEABILITY 397
25. Renner, O., t)ber die Berechnung des osmotischen Druckes. Biol.
• Centralbl. 32:486-504. 1912.
26. Rysselberghe, Fr. Van, Influence de la temperature sur la permeabilite
[ * du protoplasme vivant pour l'eau et des substances dissoutes. Bull.
I Acad. Roy. Belg. CI. Sci. 173-221. 1901.
27. Schroeder, C, Uber die selection permeable Hiille des Weizenkernes.
> Flora 102:186-208. 191 1.
| 28. Shull, Chas. A., Semipermeability of seed coats. Bot. Gaz. 56:169-199.
1913.
29, Snyder, Chas. D., On the meaning of variation in the magnitude of
temperature coefficients of physiological processes. Amer. J
28:167-175. 1911.
30. Wachter, W., Untersuchungen iiber den Austritt von Zuc
den
Zellen der Speicherorgane von Allium Cepa und Beta vulgaris. Jahrb
Wiss. Bot. 41:165-220. 1905.
*
.
ARBORES FRUTICESQUE CHINENSES NOVI. I
Camillo Schneider
^o Deutzia (Sect. Eudeutzia, subsect. Stenosepalae Schn.)
Rehderiana, sp.n. — Frutex ut videtur mediocris, dense breviter
ramosus; ramuli annotini biennesque dense scabriter stellato-
pilosi, rubro-fusci, vetustiores glabrescentes, cortice detersili;
gemmae parvae, perulis pluribus lanceolatis acuminatis fusco-
rubris pilosis cinctae. Folia matura papyracea, ovato-oblonga vel
sensim
margme
0.8~2 CT
cm
cm. magna
scure viridia, scabra, pilis stellatis (4-) 5-7 (-8)-radiatis subdense vel
sparsius conspersa, subtus pallidiora, subcinerascentia vel in sicco
interdum quasi caesio- viridia, in facie pleraque densius in nervis
laxius pilosa pilis 5-7-9 radiatis, nervis lateralibus utrinsecus 4-5 ;
mm
Cyma 3-8-flora, pleraque subsessilis, ramulos laterales breves 1-2
rarius ad 4 cm. longos terminans, plus minusve dense stellatopilosa ;
pedicelli graciles, fructiferi ad 5-6 mm. longi; calyx stellatoto-
mentosus pilis homomorphis 9-12-radiatis, dentibus triangulari-
lanceolatis tubum aequantibus vel subaequantibus rarius subsu-
perantibus acuminatis intus glabris; petala alba (vel lactea?),
extus sparse stellato-pilosa, ovato-vel elliptico-oblonga, apice satis
acuta, 7-9 mm. longa, 3-4 mm. lata; stamina exteriora longiora
petalis circ. duplo breviora, interiora exterioribus paullo bre\aora;
filamenta exteriorum apice manifeste bidentata dentibus latis
rectangularibus vel subtriangularibus antheram breviter stipitatam
subaequantibus vel parum superantibus interdum anthera breviori-
bus, interiorum lata, apice truncata et im
vel versus apicem sensim acuta, antheram faciei interiori circa
medium affixam gerentia; styli 3 laciniis calycis vix longiores.
Capsula hemisphaerica, circ. 3 mm. crassa, lobis erectis vel incurvis
plus minusve deciduis.
Botanical Gazette, vol. 63] [398
&
\
1917] SCHNEIDER— NEW CHINESE PLANTS 399
Yunnan occidentalis : inter Talifu et Tengyiieh, probabiliter in regionc
inter flumina Mekong et Salween, Octobri 1914, C. Schneider (no. 2613; typus
in Herb. Arb. Arn. et in Hb. Schneider).
This is a very distinct looking plant, with its small, broadly ovate, almost
subsessile leaves, and its few-flowered inflorescences which are borne on short
lateral branchlets. It seems to be most closely related to D. subsessilis Rehd.,
t which may easily be distinguished by its much longer (up to 6 cm.), more
oblong leaves whose stellate hairs of the under surface have only 4-6 rays, by
its larger and richer inflorescences, and bv its larger flowers.
It is with great pleasure that I connect with this distinct species the name
of Mr. Alfred Rehder, the well known dendrologist of the Arnold Arboretum,
who (Sargent, PI. Wils. 1:1913) has given an excellent contribution to the
I knowledge of the genus Deutzia.
i y^ Spiraea (Sect. Chamaedryon Ser.) teretiuscula, sp.n. — Frutex
latus, ad 2 m. altus, laxe ramosus, ramis subnutantibus ; ramuli
I hornotini flavescentes vel violascentes, vix sulcato-striati, puberuli,
annotini rubro-brunnei vel fusci, teretiusculi, vetustiores cineras-
centes; gemmae ut videtur parvae, ovatae, perulis imbricatis pilosis
obtectae. Folia decidua, ovalia, obovalia vel ovato-elliptica, apice
rotundata, interdum fere subemarginata, minutissime apiculata,
basi plus minusve late cuneata, 6-1 1 mm. longa, 3-7 mm. lata,
margine integerrima, superne laete viridia, tantum novella minutis-
sime puberula, cito glaberrima, subtus discoloria, cinerascentia,
initio paullo distinctius pilosa, dein etiam glabra, sub microscopio
ut in S. canescenti papillosa, nervis utrinsecus 3-4 vix visibilibus;
petioli flavescentes, vix 1.5 mm. longi, puberuli. Corymbus circ.
25-florus, convexus, tomentosulus, ramulos normaliter plurifoliatos
1-3 cm. longos terminans, 1.5-2.5 cm. diametiens; flores albi,
circ. 5 mm. diametientes ; pedicelli graciles, floribus breviores,
tomentosuli; receptacula late turbinata. extus tomentosula, intus
pilosula; sepala late triangularia, receptaculis aequilonga, extus
glabra, intus ad apicem et ad marginem fulvo-villosula; petala
suborbicularia, circ. 1 . 5 mm. lata, sepala duplo superantia; stamina
20, petalis subaequilonga ; discus distinctus 10-lobatus, lobis apice
dorsoque leviter sulcatis; carpidia extus versus basim intus ad
ventrem sparse villosa, stylis apicalibus quam stamina subduplo
brevioribus. Fructus maturi ignoti.
Szechuan australis: in regione Yen-yuan Hsien, inter viculos Ka-la-pa et
Liu-ku, in dumetis montanis, alt. circ. 3000 m., 17 Maji 19M, C. Schneider
400 BOTANICAL GAZETTE [may
(no. 1256); eadem regione, prope Kua-pie, in declivibus calcareis montium,
alt. circ. 3000 m., 23 Maji 1914, C. Schneider (no. 3546; typus in Herb. Arb.
Am. et Hb. Schneider).
At first sight, this species seems to be much like S. avails Rehd., which also
has terete branchlets and similar leaves and flowers, but which is easily dis-
tinguished by the glabrous branchlets, leaves, and inflorescence, as well as by
the leaves being not papillose beneath. According to the papillose leaves,
5. teretiuscula is more closely related to S. canescens Don, but all the forms of
this variable species have the branchlets distinctly angular.
Here may be mentioned another interesting form I collected in southern
Szechuan "in dumetis montium inter viculos Hun-ka et Wo-lo-ho, alt. circ.
3300 m., 13 Junii 1914 (no. 3525; frutex circ. 2 m. altus, alabastra rosea)/'
the flower buds of which are pink. In its angular branchlets it resembles S.
canescens, but the young ovate or ovate-elliptic leaves are not distinctly
papillose beneath. Judging by its pinkish flowers it seems to represent a new
species, but, unfortunately, the flowers are too young to furnish sufficient char-
acters for a description. The young branchlets, leaves, and inflorescences are
not quite so distinctly puberulous as in 5. teretiuscula, and they seem to become
very soon almost glabrous. The leaves are entire, and measure up to 15 mm.
in length and 7 mm. in width.
£'^* Malus pumila Mill., var. subsessilis, n.var. — A typo praecipue
recedit fructibus immaturis subsessilibus iis Docyniae Delavayi
similibus ovato-ellipticis circ. 2 . 5 cm. longis et 2 cm. crassis sparse
villosis apice concavis sepalis persistentibus conniventibus.
Szechuan australis: inter pagos Hoh-si et Te-li-pu, alt. circ. 2300 m.,
7 Maji 1914, C. Schneider (no. 1132; typus in Herb. Arb. Arn. et Hb. Schnei-
der; tantum arborem unicam mutilatam probabiliter cultam ad 5-metralem
vidi) .
The subsessile fruit of this apple suggests a Docynia, but the leaves and
flowers are that of a true Malus. So far as I can judge by the material before
me, it represents only a form of M . pumila, the variability of which needs a
careful study. To M. pumila sensu meo (111. Handb. Laubh. 1:715- I 9°5)
certainly belongs M. asiatica Nakai in Matsumura, Icon. PL Koisik. 3: 19. pi*
\$ft Malus (Sect. Docyniopsis Schn.) docynioides, sp.n. — Arbus-
cula squarrosa, ad 6 m. alta; ramuli novelli griseo-villosi, floriferi
laxius villosuli ut vetustiores glabrescentes f uscescentes ; gemmae
satis evolutae ignotae. Folia partim sempervirentia, tenuiter
coriacea, biennia elliptico-oblonga vel obovato-elliptica, apice plus
minusve rotundata sed apiculata, basim versus sensim attenuata,
cuneata, margine subintegerrima vel a medio ad apicem indistincte
i9i 7] SCHNEIDER— NEW CHINESE PLANTS 401
glanduloso-crenulata, 2-5.5 cm. longa, 0.7-2 cm. lata vel latiora
ad 4.5:2.3cm. magna, superne intense viridia, nitidula, glabra,
subtus pallidiora, laxe villosula, costa nervisque lateralibus utrin-
secus plerisque 5 prominulis flavescentibus glabrioribus, petiolis
superne sulcatis saepissime laxe villosulis ad 1 cm. longis; folia
novella versus apicem pleraque distinctius crenato-dentata vel
irregulariter sublobulato-dentata, ad 3:1.7 cm. magna, superne
in costa sparse lanuginosa, subtus satis dense griseo- villosula, in
costa nervisque tomentella, petiolis ad 8 mm. longis tomentellis.
Flores ad 1-3 fasciculati, fere sessiles, albi, circ. 2.5 mm. diameti-
entes; sepala 4-5 mm. longa, late triangularia, subito breviter
acuminata, utrinque satis dense lanuginosa, receptaculo dense
griseo-villoso-tomentello subaequilonga ; petala ovalia. apice rotun-
data, basi breviter unguiculata, circ. 13 mm. longa et 7 mm. lata;
stamina circ. 30, longiora petalis triente breviora, antheris flavis;
st yli 5> parte inferiore connati, paullo supra basim villosuli, stamini-
bus longioribus breviores; ovarium 5-loculare, loculis in stylorum
basi distincte product is 2-ovulatis ovulis plus minus ve superim-
positis vel appositis. Fructus ignoti.
Szechuan australis: inter Kua-pie et Ta-tiao-ko, alt. circ. 2700 m., 23 Maji
1914, Schneider (no. 1349; typus in Herb. Arb. Arn. et Hb. Schneider).
The old leaves of this strange Mains are very much like those of Docynia
Delavayi (Fr.) Schn., which are almost entire but sometimes show a similar
dentation. The flowers, however, of M. docynioides are different from those
of a true Docynia in having only 2 ovules in each carpel, while in D. Delavayi
as well in D. indica Decne. I have always found 4-6 ovules. Otherwise the
structure of the ovary of our new species agrees with that of the ovary of M.
Tschonoskii (Max.) Schn. which, as I have pointed out (Fedde, Rep. spec,
nov. 3 : 1 79. 1906) , may represent the type of a new section for which I proposed
the name Docyniopsis. The figure given in Sargent's Trees and Shrubs 1 :
Pi- 37, fig- <?. 1903 is incorrect, and has been copied by myself in my III. Handb.
Laubh. 1 :fig. 403/1; the cells of the ovary are distinctly protruding into the
base of the styles. As Rehder has stated (Sargent, I.e. 74), the separation
of the genus Docynia from Mains, especially from the group formerly regarded
as genus Eriolobus, is rather an artificial one. But, after all, I hesitate to unite
the true species of Docynia with Mains, and I refer to this genus all the species
which possess only 2 (very rarely 3) ovules in each cell of the ovary, while
Docynia may be distinguished by its 4-6-ovuIate carpels.
ifi** Sorbus (Sect. Aria) Ambrozyana, sp.n.— Frutex elatus vel arbor
parva, habitu 5. Ariae; ramuli annotini glabri, fusco-purpurei,
402 BOTAXICAL GAZETTE [may
lenticellis flavis sparse obtecti, vetustiores f usco-nigrescentes ;
gemmae ovato-oblongae, acuminatae, perulis paucis fusco-purpureis
margine dense longiciliatis cinctae, divaricatae, laterales 7-8 mm.,
terminales circ. 10 mm. (vel ultra ?) longae. Folia decidua, sub-
chartacea, pleraque elliptico-oblonga, minora interdum ovato-
elliptica et maxima obovato-oblonga, apice acuta vel plus minusve
rarius distincte acuminata, basi satis acute vel late cuneata, rarius
*
subrotundata, minora latiora 6-7 cm. longa et 2.5-3.5 cm. lata,
oblonga majora 7:2.5 ad 15:4 cm. vel latiora ad 14:6 cm. magna,
margine irregulariter vel dupliciter subglanduloso-denticulata vel
sublobata, superne saturate viridia, paullo nitidula, glabra (vel
juniora ut videtur in costa nervisque subimpressis sparse pilosa),
subtus valde discoloria, pulchre albescentia vel leviter flavescentia,
facie tomento lanuginoso adpresso obtecta, costa nervisque laterali-
bus utrinsecus 9-10 subrectis in dentes exeuntibus angulo circ. 45
a costa divergentibus prominentibus sparsius lanuginosis vel fere
glabrescentibus colore flavescente conspicuis; petioli 1-2 cm. longi,
flavescentes, superne canaliculati, sparse lanuginosi vel fere glabri.
Inflorescentia valde deflorata vel fructifera ramos laterales nor-
maliter 2-3-foliatos ad 3 cm. longos terminans, corymbosa, circ.
5 cm. longa et lata, sparse pilosa vel glabra, fructibus 3-6; pedi-
celli circ. 5 mm. longi ; sepala florum valde defloratorum late vel
satis anguste triangularia, partem liberam receptaculi aequantia,
initio ut receptaculum lanuginosa, deinde ambo glabra; petala
ignota; stamina ut videtur circ. 25; discus cupularis, glaber;
styli 2, 2/3 connati, basi parce lanuginosi; ovarium totum inferum,
carpellis ventre ut videtur tantum basi connatis in parte libera
parce lanuginosis; fructus rubri, obovato-globosi, ad 12:12 vel
15:13 mm. magni, apice parte libera receptaculi et parte inferiore
persistente stylorum coronati sepalis plus minusve deciduis, sparse
punctati; semina obovalia, valde compressa, apice rotundata, basi
sub hilo apiculata, 5-6 mm. longa, 3-3.5 mm. lata, flavo-brunnea.
Yunnan boreali-occidentalis: ad latera orientalia montium niveorum prope
Lichiang-fu, alt. circ. 3200 m., Octobri 1914, C. Schneider (no. 3913, typus in
Herb. Arb. Arn. et Hb. Schneider).
The nearest relatives of this species seem to be 5. Aria Crtz. and S. lanata
Koch, from both of which it may at once be distinguished by its much shorter
sepals and the different serration and lobation of the leaves. The shape of
1917] SCHNEIDER— NEW CHINESE PLANTS ' 403
its rather narrow and long leaves is different from that of all the other Asiatic
species of this group, and I cannot identify it with any species mentioned by
Rehder in his Conspectus specierum Asiae orientalis (Sargent, PL Wils.
2:272. 191 5), nor with any other form known to me.
The name is given in honor of Count 1st van Ambrozy, a very successful
garden maker on his famous estate at Malonya, Hungary, as a slight return
for all his help in my dendrological studies.
perta
St Sorbus hupehensis Schn. , var . aperta, n. var. — S. <
in Sargent, PI. Wils. 1:465. 1913. — A typo praecipue recedit foliis
U-)5, non 6-8-jugis, foliolorum paribus in rhachide interstitiis pie-
risque 1 .8-2 .3 cm. longis separatis.
See my remarks under the following variety.
qfi Sorbus hupehensis, var. obtusa, n. var. — A typo praecipue
recedit foliis 4-5-jugis, foliolorum paribus in rhachide interstitiis
1.5-2.5 cm. longis separatis, foliolis apice distincte obtusis margine
tantum triente superiori dentibus utrinsecus 3-9 serratis maximis
lateralium ad 5.5:2.2 cm. magnis subtus sub microscopio undique^
satis dense papillosis.
Yunnan boreali-occidentalis: prope Yung-ning, 19 Junii 1914, C. Schneider
(no. 1166; typus in Herb. Arb. Arn. et Hb. Schneider; arbor circ. 8 m. alta).
In determining the Sorbus of the Auc upari a-groxxp collected by myself
in southern Szechuan and northwestern Yunnan, I cannot refer the above
form to any species or variety enumerated by KOEHNE in his Sorborum chitten-
slum conspectus analyticus (Sargent, PL Wils. 1:475. 1913)- ll seems to
me most nearly related to S. aperta Koeh., from the type of which it differs
by its 5-6 (instead of 4-5) pairs of leaflets which are distinctly obtuse at their
apex and also distinctly papillose beneath. As in S. aperta, the pairs of leaflets
are more distant on the rhachis, and the leaflets are somewhat larger than in
typical S. hupehensis. Otherwise, var. obtusa seems to connect the latter with
5. aperta, and I am unable to detect sufficient differences to keep S. aperta a
distinct species. I make it, therefore, a variety of S. hupehensis, of which it
represents the most northern form, chiefly distinguished by its fewer pairs of
leaflets.
To the typical 5. hupehensis Schn. (in Bull. Herb. Boiss. II. 6:316. 1906;
fig- 374*
ifi
(see later) if it is possible to keep this form even as a variety.
Szechuan australis: inter pagos Wo-lo-ho et Hun-ka, in silvis apertis
montium, alt. circ. 3000-3400 m., 13 Junii 1914, C. Schneider (no. 3532; arbor
circ. 10 m. alta, trunco circ. 0.6 m. crasso; flores odore valde ingrato).
404 * . BOTAMCAL GAZETTE [may
Yunnan boreali-occidentalis : ad latera orientalia montium niveorum prope
Lichiang-fu, in dumetis apertis, alt. circ. 3500 m., Octobri 1914, C. Schneider
(no. 2829 et 3912; fructus maturi carnei); eodem loco et tempore (no. 281 1;
fructus carnei; gemmae apice distinctius rufo-lanatae) ; in angustiis montium
inter Sung-queh et Teng-chuan, 29 Septembris 1914, C. Schneider (no. 2905;
arbor ad 8 m. alta; fructus carnei; gemmae ut in no. 281 1 rufo-lanatae;
rhachis folio rum ad 9-jugorum apicem versus distinctius alata; folia surculorum
a me in eadem arbore abscissorum minora ad 12-juga foliolis tantum ad 2:0.
7 cm. magnis iis 5. Pratt ii non absimilibus) .
The fruiting branch of no. 2905 agrees well with that of no. 281 1, both
showing the buds distinctly fulvous at the apex, and the narrow wings of the
rhachis. I do not know whether these two numbers represent another form
because I have not yet seen fully developed buds of typical S. hupehensis.
In nos. 2829 and 3912 the buds are much more glabrous, and the rhachis
is almost wingless. I am at a loss how to distinguish these specimens from the
type of S. laxiflora Koehne collected by E. H. Wilson in western Szechuan,
northeast of Tachien-lu,on the Ta-p'ao-shan, July 4, 1908 (no. 3008), and there-
fore I propose the following variety:
*/>* 1 Sorbus hupehensis, var. laxiflora, n. var. — S. laxiflora Koeh.
in Sargent, PL Wils. 1:466. 1913.
It needs further investigation to determine how this variety may really be
distinguished from typical S. hupehensis. Koehxe himself says that S. laxi-
flora forms with S. hupehensis and S. aperta "a special group distinguished by
its small stipules, medium-sized leaves with 4-7 pairs of medium-sized leaflets,
and by a remarkably loose inflorescence."
There is another group of species described by Koehne which I cannot
separate because the characters on which they are founded by the author are
too variable according to my own observations. I therefore propose to unite
them in the following manner:
<*^ Sorbus Prattii Koeh., var. tatsienensis, n. var. — S. munda
Koeh. in Sargent, PI. Wils. 1:469. 1913, includ. f.a. tatsienensis
et f.b. subarachnoidea. — S. pogonopetala Koeh., I.e. 473. — A typo
nonnisi foliolis paullo maioribus saeDissime basi tantum integer-
rimis
type
know how to distinguish 5. munda as a variety from S. Prattii. In describing
type
300
the author has seen, came from the same locality (Pan-lan-shan, west of Kuan
Usien) as Wilsons no. 4323 which Koehne makes the type of his S. munda f.
subarachnoidea. But this fruiting specimen agrees in every respect with the
1917]
SCHNEIDER— NEW CHINESE PLANTS
405
flowering one, the only difference I can detect being that the pubescence is
somewhat fulvous, while it is greyish in no. 3003. Koehne says: "Sorbus
pogonopctala differs from all the other Chinese species with numerous small
leaflets in its strongly bearded petals; it is also remarkable in the purplish
black color of its petioles and rhachis." The last mentioned character is, in
my opinion, judging by the co-type before me, of no value, and apparently
only due to an effect of drying. The hairy petals are also present in S. Prattii,
in the description of which the author himself says "petala . . . medio supra
parce tenere lanato-barbata." I fail to see any difference between the "beards"
of 5. Prattii and of 5. pogonopetala.
Of both S. Prattii and S. munda, Koehne has described two forms, the
first one, of course, representing nothing else than the type. In reducing
S. munda to a variety of S. Prattii, the name of Koehne's f .a. tatsienensis has
to be used, according to international rules, as the new varietal name. It may
also be mentioned that the presence or absence of papillae on the under surface
of- the leaves is a rather doubtful character to base any varieties or even species
upon. In our case, the younger leaves of S. pogonostyla are "subtus epapil-
losa," while of 5. munda they are described as "subtus sat valide papillosa,
inter papillas parce v. haud reticulato-striata." In the specimen of S. munda
(no. 4323) before me the leaves may better be described as "subtus satis
indistincte papillosa," and the kind of papillae observed on the leaves of these
species of Sorbus seems to be always much more indistinctly developed on the
younger leaves than on the mature ones, and they are quite often entirely
absent "non nisi circa stomata." After all, I believe we ought not to lay too
much stress upon the development or absence of these papillae.
Arnold Arboretum
Jamaica Plain, Mass.
\
PECULIAR EFFECTS OF BARIUM, STRONTIUM, AND
CERIUM ON SPIROGYRA
S. S. Chien
(with two figures)
It has been pointed out by Osterhout 1 that dilute solutions of
BaCl 2 (o.ooi-o.oooi M) have a specific effect on certain species
of Spirogyra. They produce a peculiar contraction of the chloro-
plasts in the middle of the cell which is very characteristic. This
effect was not produced at this dilution by any of the other salts
examined. As specific effects of this kind are uncommon, it seemed
desirable to investigate the matter further.
Two species of Spirogyra were investigated, a large form of the
S. crassa type, which was used by Osterhout, and a smaller species.
The method of contraction differs somewhat in the two species.
In both kinds contraction usually begins in the region near the ends
of the cell, but in the larger kind the chloroplasts sometimes begin
to contract in the central region. In a large percentage of the cells
of the larger kind the central region shows the greatest contraction.
The chloroplasts in this region may either shrink away from one
side of the cell wall more than from the other, or equally from all
sides. In the latter case the final shape (fig. i , B) assumed by these
bodies is quite typical for this kind of Spirogyra. In the smaller
kind the greatest shrinking occurs in regions between the center and
the ends of the cell (fig. 2, B). These are cells of the larger kind,
however, whose chloroplasts contract like those of the smaller kind,
and vice versa. In general the longer cells of each species are apt
to contract most toward the ends, while the shorter cells are apt
to have the greatest contraction in the middle. In either case the
contractions of the chloroplasts are very characteristic.
Contraction usually takes place a few minutes after the applica-
tion of the solutions. Table I shows the time necessary for pro-
ducing the effect at different solutions.
1 Osterhout, \Y. J. V., Specific action of barium. Amer. Jour. Botany 3:481-
482. igi6.
Botanical Gazette, vol. 63]
[406
IOI?]
CHIEN—SPIROG I RA
407
The last named dilution of each salt is the lowest dilution at
which contraction appears. CeCl 3 produces contraction of the
larger kind only. It is also seen from the table that the lower
TABLE I
►
For the larger kind of Spirogyra
For the smaller kind of Spirogyra
*
Solution
Time
in minutes
Solution
Time
in minutes
CeCL 0.005 M 1 8
Bad* 0.05 jVI
1-2
0.001 M
9
9
9
10
4
5
7
2-5
12
0.01 M
2-5
1 S
. 0005 M
0.0001 M
SrCL 05M
. 0000 5 M . . .
2-3
3-4
0.01 M
BaCl 2 o.oos M
0.001 M
O.OOOs M
SrCl 2 0.01 M
. 005 M
A
\
B
Fig. i.
normal
limit of CeCl 3 solution which produces the effect is less than that
of the BaCl 2 solution, but the table shows that the effect is pro-
duced more rapidly in BaCl 2 and in SrCl 2 than in CeCl 3 . These
'
408
BOTANICAL GAZETTE
[may
two kinds of Spirogyra are different also in respect to the phe-
nomena of antagonism, which will be discussed later.
If a contraction appears only after some hours or days, it is
disregarded, as in such long experiments complicating factors are
present. Solutions of barium and strontium salts in lower con-
centrations than those indicated will not produce the effect in
24 hours. With other salts which usually do not produce the effect
contractions sometimes
appear after 3 or 4 hours
(or after several days) , but
this may be due to other
than the salts,
because in material dying
agencies
A
B
Fig. 2.
form
pyrenoids omitted; A, normal condition; jB,
after treatment with BaCl 2 .
and was found to be sensitive to both barium
from natural causes cells
with contracted chromato-
phores are sometimes
found .
The material used for
this purpose must be fresh
and in good condition, or
it will lose its sensitiveness
and fail to contract when
the salts are applied. For
example, material was
taken at first from a glass
jar kept in the greenhouse
J
strontium
Later this material deteriorated because of the increased sunlight
and heat of the greenhouse, and did not respond to SrCL. although
still responding to BaCl 2 . Still later it became insensitive to BaCL
solution, even at the concentration of 0.1 M. The same thing
occurred with the small form which grew in a pond. This decrease
of sensitiveness seems to be due to some chemical or physical
change in the cell when its vitality is injured, which prevents the
chromatophores from contracting.
As this visible effect of barium, strontium,' and cerium is well
suited to the study of antagonism, attempts were made to see
what salts hinder or prevent these effects.
iq 1 7l CHIEN—SPIROGYRA 409
Some experiments were made with the smaller kind of Spirogyra
in order to see whether antagonism occurs. BaCl 2 and SrCl 2 have
no antagonistic action on each other. CaCl 2 and CeCl 3 (neither of
which causes contraction of the chromatophores by itself) are able
to antagonize BaCl 2 , and CeCl 3 is more effective than BaCl 2 .
The chromatophores do not contract when placed in a mixture
made by adding 10 cc. of 0.04 M CeCl 3 to 90 cc. of 0.08 M BaCl 2
in an hour and a half (after which the experiment was discontinued) ;
while if 10 cc. distilled water is added to 90 cc. of the same BaCl 2 ,
contraction begins after 1.5 minutes. Antagonism is obtained
also by mixing 60 cc. of o. 1 M Cacl 2 with 40 cc. of o. 1 M BaCl 2 .
In this mixture no contraction occurs in 1 hour, while if 60 cc. of
distilled water is used in the mixture in place of CaCl 2 , the con-
traction occurs in 2 minutes. The proportions here mentioned are
approximately the optimum ones for each mixture.
Summary
1. The chloroplasts of certain species of Spirogyra contract
away from the cell wall in a peculiar and characteristic fashion in
solutions CeCl 3 , BaCl 2 , and SrCl 2 (in the case of the smaller kind
in the last 2 only). The effect is observed in dilutions as great as
0.00005 M CeCl 3 (in the case of the larger species), and in o. 0001 M
BaCl 2 . SrCl 2 also produces this effect, but not at such great dilu-
tions as CeCL and BaCl 2 .
In the smaller species of Sp
2 is
inhibited when BaCl 2 is mixed with CeCl 3 or CeCl 2 in proper
proportions.
Laboratory of Plant Physiology
Harvard Umv
BRIEFER ARTICLES
MANIPULATING MICROSCOPIC ORGANISMS IN STAINING 1
Perhaps the chief limiting factor in the successful preparation of
permanent microscopic mounts of unicellular and colonial organisms is
the difficulty of manipulation during the staining, with the incidental
loss of the material in the necessary changing of the staining and washing
solutions. The small size of such forms as Sphaerella, Pandorina,
Volvox, Pediastrum, and the desmids renders these organisms especially
liable to loss in these parts of the process. When handling the very small
forms, the usual precautions taken in staining filamentous algae are
generally wholly inadequate to prevent the loss of the material.
The difficulties in the way of success, however, may be overcome by
using a funnel, filter paper, and a wash bottle, and combining the careful
manipulations of quantitative chemistry, to prevent loss of valuable
material, with the dehydration and staining methods of the Venetian
turpentine method of mounting algae. 2 After the organisms have been
killed in the usual i : 1 1400 chromacetic acid solution, the entire contents
of the vessel can be filtered, leaving the material to be stained on the
filter paper in the funnel. Complete washing to remove the killing
fluid can be secured by the use of the wash bottle. Should it be desirable
to let the material stand in water for a few hours, the filter paper may
be punctured and the material washed out into a beaker (this will save
the work of washing). Refiltering later will leave the material on the
filter paper and, with a little washing with water from the wash bottle,
ready for the staining.
This manipulation is especially adapted to use with the iron-alum
haematoxylin stain. The staining method itself may be greatly short-
ened, and in the modified form gives splendid results with these lower
forms. The iron-alum should be dissolved in distilled water and all
water treatments of material should be made with distilled water to
avoid precipitates. Weak solutions of iron-alum should be used, o 1
per cent solution at most. Frequently a few drops of a 1 per cent
Col-
1 Contribution from the Department of Botany, Pennsylvania State
lege, no. 8. '
2 Chamberlain, Chas. J., Methods in plant histology, 3d ed. Chicago, 1915
Botanical Gazette, voL 63]
[410
I
1917I BRIEFER ARTICLES 411
solution in 100 cc. of water are sufficient. The iron-alum solution is
the
After
a short time, 15-30 minutes or even less being sufficient, the material
is washed thoroughly with distilled water from the wash bottle. A weak
haematoxylin stain is then applied slowly to the material, and repeated
f observations of specimen mounts under the microscope will determine
when the staining is complete. A 0.1 per cent haematoxylin stain is
strong enough, and 30 minutes or less time is long enough for it to act.
When
distilled,
destaining with the o . 1 per cent iron-alum solutions. This latter step
is the one requiring the greatest care, since it can be overdone most
easily; the light haematoxylin stain used in the method is easily lost
by prolonged treatment with even a very weak iron-alum solution. One
application of the destaining solution is generally sufficient if care be
taken that the material is thoroughly saturated with the solution. As
1
usual when using the iron-alum solution for differentiating a stain, the
process should be closely observed under the microscope. It is to be
understood that no directions concerning the time limits can be given
for the use of either the staining or differentiating solutions, since success
depends upon the proper balancing of these two processes. When
the stain has been properly differentiated, the material should be thor-
oughly washed with distilled water from the wash bottle. At any
stage of the process, should it be desired to allow the material to remain
covered by the solution being used, this can be accomplished by fitting
a short piece of rubber tubing over the stem of the funnel and using a
clamp to stop the flow of the solution.
Dehydration is accomplished by the glycerine dehydration method
in general use. The transfer to the 5 per cent glycerine solution is made
by puncturing the filter paper and washing with the glycerine solution
into an open vessel, such as a Petri dish. The minimum amount of
glycerine should be used, since it is difficult to remove. After a few
days' exposure to evaporation, the glycerine solution is concentrated.
The material is again poured into the filter paper in the funnel and
complete dehydration accomplished by washing all the glycerine out
with 95 per cent alcohol, followed by absolute alcohol to complete
dehydration. There should be no doubt about the thoroughness of
this part of the process, since complete dehydration is essential to
success. When completely dehydrated the material is transferred
quickly to a 10 per cent Venetian turpentine solution and placed in a
412 BOTANICAL GAZETTE [may
desiccator and allowed to concentrate according to the directions given
for the Venetian turpentine method.
Should it be desired to use some of the other stains, such as the
Magdala red-anilin blue combination recommended for algae, it will be
necessary to modify this manipulation to suit the method. Since these
stains are used in strong alcoholic solutions, the material to be stained
is washed after killing by the method already described, and then
dehydrated by the glycerine method before staining. The glycerine
is washed out with 95 per cent alcohol and the stains applied.
Summary
. Treat the material the proper length of time in a suitable killing
solution.
2.
Filter the material to remove killing solution, leaving the material
on the filter paper in the funnel.
3. Wash with distilled water from a wash bottle.
1
4. Treat with a 0.1 per cent (or less) iron-alum solution.
5. Wash with distilled water, using wash bottle.
6. Stain by application of o . 1 per cent (or less) aqueous haematoxylin
stain.
Wash
8. Differentiate the stain with 0.1 per cent iron-alum solution,
washing with distilled water very thoroughly after the treatment.
9. Dehydrate with glycerine and mount by Venetian turpentine
method.
10. Vary the treatment, when alcoholic stains are to be used, by
dehydrating before staining. — J. Ben Hill, Pennsylvania State College,
State College, Pa. *
THE BOTANICAL STATION AT CINCHONA
The Botanical Station at Cinchona, in the Blue Mountains of
Jamaica, which from 1903 to 19 13 was leased by the New York Botanical
Garden, has now been leased by the Smithsonian Institution, on behalf
of 14 American botanists and botanical institutions that have con-
tributed the rental.
that
counterpart
zorg Garden of Java. They hope that the opening of this laboratory at
Cinchona may prove as stimulating to the development of botany in
'
>
¥
1917] BRIEFER ARTICLES 413
this country as the opportunities afforded at Buitenzorg have been to
the advance of this science in Europe.
The equipment available at the Station consists of the residence with
its furnishings, 3 laboratory buildings, 2 glass propagating houses, and
a garden of 10 acres containing many species of exotic shrubs and trees,
besides many native plants from the highlands of Jamaica. The occu-
pant of Cinchona is also free, within reasonable bounds, to study and
collect plants over the many thousand acres of the whole Cinchona
reservation, as well as in the neighboring valleys belonging to private
owners. He will likewise be given every available facility for study at
Hope Gardens, where he will find an herbarium, a library, and an exten-
sive collection of tropical plants. The same privilege will be his at
Castleton Garden, which contains fine collections of cycads and palms,
and of Ficus and other dicotyledonous trees.
The many different types of native vegetation accessible from Cin-
chona and from Hope include a number of great ecological interest and
numerous species of importance for the morphologist, cytologist, and
physiologist. The ecological types range from the cool mountain forest
with its tree ferns, epiphytes, and water soaked filmy ferns, to the hot,
steaming w r oods of the lowlands of the north side at one extreme, and to
the dry savannas and cactus deserts near Kingston at the other. Fuller
statements of the opportunities for research in various lines, written by
men who have worked there, may be found in Science 43:917. 1916 (see
also Popular Science Monthly, January 191 5).
Any American investigator may be granted the use of the Cinchona
Station by the Cinchona Committee, which consists of X. L. Britton,
John M. Coulter, and Duncan S. Johnson. Applications for this
privilege and for information regarding the conditions under which it
is granted should be sent to the writer. — Duncan S. Johnson, Johns
Hopkins University, Baltimore, Md.
CURRENT LITERATURE
BOOK REVIEWS
Vegetation of Paraguay
Chodat 1 has issued the first of a series of bulletins upon the plants of
Paraguay. The work on which the series is based includes investigation con-
tinued at intervals since 1889 and culminating in an expedition made in 1914
by Chodat and his former pupil Vischer, and authorized by the Federal
Department of the Interior of Switzerland. Sketches, water colors, and
photographs were made in the field, as were also some chemical tests. A large
quantity of material was brought home for later study.
The first chapter treats of the climatology and physiography of the country.
The discussion of climate is based upon records covering 30 years, made by
Bertoni at Asuncion on the Paraguay River and at Puerto-Bertoni on the
Alto-Parana. The eastern part of Paraguay has a subtropical climate of the
Chinese type; the western part is more like the Mediterranean region. Topo-
graphically, the state may be divided into the depressions along the Paraguay
River and the mountains of the east. A lower highland of about 300 m. ele-
vation separates the 2 main depressions, that about Lake Ypacarai and the
lowland around the Ypoa lagoon. This cordillera extends nearly east and
west between the Rio Salado and Rio Manduvira, and these 2 depressions are
the regions under discussion in this paper.
Chodat then takes up the Solanaceae, a group of intermediate importance,
which compose several distinct formations, and gives somewhat in detail the
variations in adaptation for climbing found in the liana forms, and the ana-
tomical changes which occur during curvature. Only a few species are insect
pollinated, those having large tubular flowers being visited by lepidopterous
insects and humming birds. The genera Sessea and Grabowskia are here
reported for the first time for the Paraguay flora. Indigo w r as found present
in 2 species not previously known to contain the pigment. A few species of the
family find in Paraguay their southern limit, while a somewhat larger number
reach here their most northern extension. Several are mentioned as
endemic and some of these are extremely local. In the third chapter the
author discusses the Hydnoraceae, largely from a morphological standpoint.
The one genus given (Prosopanche) is reported as parasitic on the roots of
Prosopis and some of the Solanaceae.
1 Chodat, R., and Vischer, W., La vegetation du Paraguay. 1st fascicle.
8vo. pp. 157. ph. 3. figs. 123. Geneve. 1916.
414
•
V
1917] CURRENT LITERATURE 415
The last chapter deals with the dominant group of the region, the Brome-
liaceae. The 2 main divisions considered are the cistern plants and the epi-
phytic Tillatidsias. The latter are divided into those which lean against the
support and those having some means of attachment to it. The different
adaptations for climbing are illustrated. The structure and function of
the hairs of Tillandsia and of the hairs on the submerged leaf bases of the
cistern species are given particular attention. The presence of cortical roots
in the attached lianas is also noted and their value to the plant discussed.
Here, as in the Solanaceae, insect pollination is not very common, but the
humming bird is a regular visitor to some large-flowered species. A few of
the Bromeliaceae, as Tillandsia usneoides and T. recurvata, have a range from
southern United States or Mexico to the southern part of South America.
Most of the species mentioned, however, are limited to South America, 9 being
given as endemic. The author also includes in this chapter a very interesting
description of the xerophytic rupicole species belonging to various families
which are found on the rocks of Cerro San Tomas and Sierra d'Acahay. —
Ak a villa Taylor.
NOTES FOR STUDENTS
Puget Sound algae. — A fascicle of papers 2 from the Puget Sound Marine
Station at Friday Harbor, Washington, gives the results of work done on
algae at the station, largely during the summer of 1916.
Miss Hurd finds that young bladder kelps (Nereocystis) can adapt them-
selves to 55 per cent of fresh water in their environment if the change is made
gradually. She concludes that rapid elongation of this plant is due to low light
intensity in the water, and that growth of the stipe is greatly retarded by
strong light when the bulb approaches the surface of the water. The fact that
this does not act as a very exact determiner of length is readily understood,
when we remember that the variation from extreme high tide to extreme low
tide during the growing season in this region is more than 12 ft. She reaches
the conclusion that there is no relation between rate of growth and mechanical
stretching in the stipe of the plant. The experimental evidence given seems to
justify this conclusion, providing that nothing else (for example, light) was
a limiting factor in both exneriment and control.
adhaerens
J
Sound is C. dimorphum Sved., since it has no utricle hairs and has two types
of utricles, the one with unmodified end wall and the other with thickened,
striated end wall.
predominance
thick or of thin end walls in the utricles is probably due to differences in envi-
ronment. The thick-walled type sometimes
2 Puget Sound Marine Station Publications i:nos. 17-24. 185-248. pis. 33-466
1916.
416 BOTANICAL GAZETTE . [may
'
thallus, sometimes is found only around the margin and on the under side of the
lobes, and sometimes is wanting entirely.
Muenscher reports a list of marine algae found on Shaw Island (one of
the San Juan group) , with notes as to zonal distribution and relative abundance,
and a discussion of the ecological factors involved. He finds 54 Rhodophyceae,
31 Phaeophyceae, 15 Chlorophyceae, and 3 Myxophyceae. The plates give
the distribution at various points on the island and will be very useful to col-
lectors of algae in the region.
Miss Kibbe reports the presence of a parasitic fungus {Chytridium alarium,
sp. nov.) on Alariafistulosa collected in Alaska. She examined all of the species
of brown algae that were readily available at the Puget Sound Marine Station,
and also specimens of Alaria valida from Alaska, and did not find any trace of
this fungus in any of them. In A . fistulosa she found the fungus in various
forms in all parts of the plant except the heavy older portions of the stipe.
Miss Karrer finds that some light is thrown on the metabolism of Nereo-
cystis by chemical reactions whose results are seen under the microscope.
She finds that the cell walls are made up of cellulose and algin, the latter being
probably the substance that holds the cells together. She finds that the
presence of the inorganic substances (calcium, magnesium, sodium, potassium,
chlorine, sulphates, carbonates, phosphates, and iodine) whose presence in the
plant have often been shown by analytical chemists can be demonstrated in the
cell by using the methods suggested by Tunmann 3 and Molisch 4 with slight
modifications.
Miss Clark reports the acidity of marine algae as determined by titration.
She reports that all of the 3 1 species tested were acid.
Langdon 5 finds that carbon monoxide is present in the float of the bladder
kelp (Nereocystis), the quantity varying considerably in different individuals.
He finds the presence of carbon dioxide to be only occasional and the quantity
minute. He does not find confirmation of previous work tending to show
that the quantity of carbon dioxide and of oxygen vary with the time of day.
He suggests that since theories of photosynthesis have largely been concerned
with carbon monoxide and its reduction product formaldehyde, and with
formic acid, of which carbon monoxide may be considered the anhydride, it is
possible that the occurrence of carbon monoxide in plant tissues may be more
general than has been supposed. Apparently Langdon's work is the first
demonstration of free carbon monoxide in a living plant. A large plant cavity
surrounded by rapidly growing tissue furnishes an unusually favorable oppor-
tunity for the investigation of gases taking part in metabolism. The sieve
tubes in this plant are in the mycelium-like pith web on the interior surface of
3 Tunmann, O., Pflanzenmicrochemie. Berlin. 1913.
4 Molisch, H., Microchemie der Pflanzen. Jena. 1913.
s The substance of this paper has also been published in Jour. Amer. Chem. Soc
39:149-156. 1917.
i9i 7] CURRENT LITERATURE 417
the float. Since the whole surface of the sieve tubes in this portion of the plant
is thus exposed to the gas contained in this float, it would seem possible that
considerable oxidation of foods is carried on in this internal atmosphere. The
gas in this float is shown to contain a little larger percentage of oxygen than
air. It may possibly be worth while to consider the presence of carbon mon-
oxide in plants in connection with the wide distribution of oxidases in plant
tissue and the possible mechanism of their reaction. 6 Langdox's thorough
demonstration of the presence of carbon monoxide in this cavity is a very
important piece of work, and great interest attaches to the possible relation of
this gas to the metabolism of the plant.— G. B. Rigg.
Quantitative characters in beans. — By means of a statistical study of pole
and bush beans, Emerson 7 has analyzed the characters causing height varia-
tion in Phaseolus vulgaris. They are 3 in number and apparently segregate
independently after crossing. First is the manner of growth, which is either
"determinate" (bush type) or " indeterminate " (pole type), with the inde-
terminate habit completely dominant in the Fi generation, and showing the
typical 3 : 1 splitting in the F 2 generation. Such behavior he interprets as the
result of a single pair of freely segregating factors behaving in a Mendelian
fashion.
Tschermak, using the hybrids Phaseolus vulgar isX P. multiflorus and the
reciprocal, found anomalous splitting in the F 2 , since some of the " short"
segregates produced "tails" in succeeding generations. He makes no mention
of habit of growth, and merely classifies the progenies as " tails" and "shorts."
The results of Tschermak need not be compared with Emerson's, however,
because in the former case the hybrids are interspecific, and in the latter inter-
varietal (intraspecific).
The second character operative in determining height is number of inter-
nodes. The presence of this character was deduced from the fact that differ-
ent varieties of both pole and bush beans differed in the number of internodes
produced when grown under the same conditions. The question then arose
as to whether this tendency to produce few or many internodes could be
inherited independently of habit of growth. Suitable crosses were made and
the results seemed to answer the question in the affirmative, although the evi-
dence is admittedly incomplete. The factors determining this difference could
not be shown to be perfectly dominant, but apparent segregation followed
hybridization. This segregation was attended in the F 2 generation by a range
of variability exceeding that of the 2 parents. Emerson interprets this result
as due to the action of multiple segregating factors.
third character involved in height is length of internode. The modi-
fication of this character by habit of growth made its behavior difficult to study.
The
6 Reed, G. B., Bot. Gaz. 62:53-64. 1916.
Emerson
Re-
search Bull. no. 7. Xebr. Agric. Exp. Sta. pp. 73. 1916.
418 BOTAMCAL GAZETTE [may
In order to have a standard of comparison between pole and bush bean types,
the first 5 internodes were measured and the means computed. For comparison
between different varieties of pole beans the mean of the first 5 internodes was
1
used. It was thought that the actual internode length found for some of the
bush varieties might not be representative of the potential length which
would have been attained by the upper internodes had not the production of
a terminal inflorescence hindered further growth. To test this supposition
crosses were made between a bush bean with long internodes and a pole
bean with short internodes. The resulting hybrid showed an intermediate
development in the F 1 and a wide range of variation in the F 2 generation.
Bush beans with shorter internodes and pole beans with longer internodes
than the parent types exhibited were obtained. Here again the variations
were attributed to the action of multiple, non-dominant, independently
segregating factors.
In conclusion, the author points out that the results of other investigators
tend to show that quantitative characters in plants are inherited in two ways:
(a) they are due to the action of a single Mendelian pair of factors showing
complete dominance in the F r and a 3 : 1 ratio in the F 2 generation ; (b) they
exhibit an intermediate development in the Fj and a wide range of variation
in the F 2 generation. In class (a) belongs the determinate as opposed to the
indeterminate habit of growth. Characters such as length and number of
internodes fall into class (6). Such characters as those of class (b) have been
interpreted in 2 ways. Emerson, Tschermak, East, and others attribute
them to the interaction of many independently segregating factors, a theory in
accord with the multiple factor hypothesis of Nilsson-Ehle. Castle,
however, has interpreted such behavior as due, in some cases, to the modifi-
cation of a unit factor through hybridization. In the case of the bean crosses,
Emerson implies that the factor involved would be that which determines
habit of growth. After discussing this latter hypothesis and the assumptions
its adoption would necessitate, he rejects it in favor of the multiple factor
hypothesis.
Since, therefore, the characters involved in producing an effect seem to
behave in different manners in inheritance, the author explains the variation
in height following hybridization between pole and bush beans as due to the
modification of the expression of a unit factor by the presence or absence of
a number of factors producing other effects (as, for example, the effect of the
determinate habit of growth on the potential length of internodes and on the
number of internodes, etc.). However, the author disavows any intention of
maintaining that this is the only possible explanation, and suggests that it may
have to be modified to suit the results of further selection and hybridization
experiments. — Wilbur Brothertox.
Philippine forests. — Our knowledge of the economic importance and the
environmental conditions of some tropical forests has been advanced by a
igiy] CURRENT LITERATURE 419
recent publication, 8 the joint product of a botanist and a forester. The former
seems to have contributed many details concerning the floristic and ecological
composition of the many variations in the dipterocarp forest. The quanti-
tative data regarding the physical climatic factors are among the first to be
collected in tropical forests according to modern methods. Soil moisture
determinations for every month in the year, although unfortunately not
accompanied by the wilting coefficient of the soil, show that the soil is quite
uniformly moist throughout the year. Atmometer records throughout the
year give for the first time the data for an adequate comparison with the evapo-
rating power of the air in mesophytic forests elsewhere. In the dipterocarp
forests of Mount Maquiling the maximum, minimum, and average daily rates
of evaporation upon the floor of the forest are respectively 5.3,0.7, and 2 . 5 cc,
as compared with 10.6, 3.3, and 7.1 cc. obtained by the reviewer 9 in the
mesophytic beech-maple forest of northern Indiana. The evaporation data
■
are especially good because they are given not only for the floor of the forest
but also for the second story trees, where there is protection by the general
canopy of foliage, and give a maximum, minimum, and average daily rate of
7. 5 ? i.8, and 5.3 cc. respectively, and for the atmosphere above the tree
tops, where the maximum, minimum, and average daily rates are 22.1, 8.4,
and 15.7 cc. The leaves of the tree tops are thus exposed to an evaporating
power of the air 6 times as great as that obtaining for the ground vegetation.
The forester's part of the report contains many data of the distribution,
composition, volume, and rate of increment of these forests. The results
show that they may, when cut and logged by modern methods, make a very
important contribution to the lumber supply of the world. In this connection
it is interesting to note that the average rates of growth of the dipterocarps are
about the same as those of the hardwoods in the central deciduous forest region
of the United States; while one of the most rapid growers, Parashorea plicata,
appears to grow about twice as fast as Liriodendron. The relative advantages
of various cutting systems are discussed, and the opinion expressed that plant-
ing of dipterocarps is not likely to be successful.
This article, together with the earlier reports of Whitford, gives a good
general ecological knowledge of these interesting forests, and should furnish
a good basis for the rapid evolution of methods of forestry which will render
these natural resources a permanent source of wealth for these islands. —
Geo. D. Fuller.
Distribution of species.— Willis in two recent papers 10 attempted to show
that the geographical distribution of species within Ceylon is to be explained,
species
Brown
Phil.
Jour. Sci. Sect. A. 9:413-561- figs. 16. 1914.
9 Bot. Gaz. 58:193-234. 1914.
10 Rev. in Bot. Gaz. 61:82. 1916; 62:160. 1916.
420 BOTAXICAL GAZETTE [may
argument upon statistics. In accordance with his theory he made a number
of predictions as to the distribution of species in New Zealand. These pre-
dictions have been verified by statistics which he has collected there, and
which he presents in his latest paper, furnishing a very striking verification of
his theory. 11
Supposing a given species to have entered the islands at a certain point,
and spread at an even rate, the area of its distribution at any time would be
a measure of its local age. It is reasonable to suppose that this species would
give rise to endemics, in increasing number as time went on, and as the area
occupied became greater. At the limits of the islands farthest from the point
where the species entered, the local age of the species, and consequently the
number of endemics to which it had given rise, would be least. Following out
such a conception, Willis predicted that the middle zones of the islands should
show a greater number of endemics than the outer zones, and this proved to
be the case.
Following the same line of thought, those endemics which were produced
early would have most nearly reached the limits of the islands in their dis-
tribution, while those produced later in the local history of the parent species
would be more limited in their distribution to the middle zones of the islands.
Consequently, the author predicted that "the range of an endemic species
would on the average be greater the nearer that one of its limits w T as to either
end of the islands.' ' This also was verified.
Another prediction made and verified was that widely distributed species
would be more widespread within the islands than endemics, as in the case of
Ceylon. On the basis that the land connection with New Zealand both ended
earlier and began earlier than that with Ceylon, the author predicted that the
average area occupied by a species in New Zealand would be greater than in
Ceylon, that is, that both "wides" and endemics would be comparatively
fewer in the lower or earlier stages in the scale. These predictions also were
verified.
Those who wish to examine the exact mathematical statement of the
author's method and conclusions are referred to the paper. — Merle C.
Coulter.
A floating reed swamp. — Occurring in the delta of the Danube River is
a remarkable form of floating swamp formed by the reed Phragmites communis
var. flavescais Gren. and Godr. It has been described by Miss Pallis, 12 who
visited and studied it in 191 2 and again in 1913. She found that this swamp,
known as Plav, differs from a closed reed sw r amp chiefly in the fact that it
floats, the surface of the mat of soil and vegetation remaining constantly about
11 Willis, J. C, The distribution of species in New Zealand. Ann. Botany 30:
4-457. fig. I- 19 1 6.
12 Pallis, Marietta, The structure and history of Plav, the floating fen of the
delta of the Danube. Jour. Linn. Soc. 43:233-290. pis, 11-23. 1916.
1917] CURRENT LITERATURE 421
4 cm. above the fluctuating surface of the water. These fluctuations of the
water level are great, as there are usually 3 floods each year, 2 in spring and
1 in autumn, the water at such times rising 1-6 m. The floating mat is made
up almost entirely of vertical rhizomes of the reed, which, with the aid of their
roots, retain much soil, the whole attaining a thickness of 0.8-2 m. The
aerial shoots vary in height from 1.2 m. to 5.15 m. This mat originates
attached to the soil, but becomes floating with the death of the basal rhizomes
and the action of such floods as are accompanied by only small depositions of
silt. The maximum size of units becoming detached is given as 2500 sq. m.
In the shallower water much of the reed mat remains permanently attached.
Little other vegetation is mingled with the Phragmitcs, its only competitor
being Typha angustifolia, which is apparently only able to inhibit its growth
for a short time. The reed seems to be succeeded by Cladium mariscus or by
an aggregation of species of Car ex.
The most remarkable part of this paper is the hypothesis offered to explain
the difference in size of the reed, varying as it does from 1.2 m. to 5.15 m.
This Miss Pallis ascribes, not to any difference of variety, but to a difference
in age. She believes that the giant shoots, 5 m. in height, have arisen earliest
and at the base of the branch system of the rhizoids, and that with progressive
advancement toward the higher parts of the branch system the aerial shoots
have become gradually smaller and shorter. The change in size is thus a senile
degeneration which ultimately results in the death of the individual. Unfortu-
nately, the necessary experimentation to prove this theory would extend over
many years and hence could not be undertaken. Many of the facts appear
to support Miss Pallis' hypothesis, and most of her argument seems sound,
but some of the evidence seems to point to overcrowding being at least one
factor in the reduction in size of shoots. More data regarding the germination
and early growth of the reed should shed light upon the question of the dura-
tion of life of the Phragmites and its final senescence and death. — Geo. I).
Fuller.
Taxonomic notes. — Ducke, 1 * in a presentation of new and little known
plants of the Amazon region, discusses 146 species, 102 of which are
Legu
cribed, 21 of which are Legu
nosae. Among the new species there is a Zamia (Z. Lecointei). The paper
appears m the initial number of a journal issued by the Botanical Garden or
Rio de Janeiro..
Greexman 1 * has published the second part of his monograph of Senecio,
including the Aurei (§ 6). He recognizes 48 species and describes 5 of them
as new. Of the new species, 2 are from the region of Newfoundland and
13 Ducke, A., Plantes nouvelles on peu connues de la region amazonienne. Archiv.
Jard. Bot. Rio de Janeiro 1 : 1-159. pis. iq. 1915.
x < Greenman, J. M., Monograph of the North and Central American species of
the genus Senecio. Part II. Ann. Mo. Bot. Gard. 3:85-194. *9 l6 -
422
BOTANICAL GAZETTE
[may
northern Maine, 2 from Utah and Nevada, and 1 from Mexico. In addition
to the full descriptions and synonymy, the citations of stations and exsiccatae
are very complete.
Griffiths 15 has described 9 new species of Opuntia, which have been grow-
ing under his observation for 5-8 years.
Pittier 16 has published a revision of Inga, a large American genus of
leguminous trees, which has not been revised since 1875. He recognizes 212
species, 40 of which are new, representing 5 sections, which are further sub-
divided into series.
Rendle 17 has published Maidenia as a new genus of Hydrocharidaceae
from West Australia. It is a delicate water plant 5-6 cm. high, covered with
numerous threadlike leaves, and belongs to the Vallisnerieae.
Werxham, 18 in a seventh paper on the Rubiaceae of the American tropics,
has published an analytical key to the genera. The extensive display of
Rubiaceae in this region is indicated by the fact that 182 genera are recognized,
distributed among 21 tribes.
Wright 19 has published a new genus (Thuranthos) of Liliaceae from South
Africa, related to Drimia Jacq. — J. M. C.
Excretion of acids by roots. — Haas 20 has taken up the much controverted
question, do roots give off acids other than carbonic ? He grew roots of early
sweet corn in distilled water for 5 and for 19 days and tested the H+ concen-
tration of the water against standard buffer solutions of phosphates with
phenolphthalein as the indicator. He concludes that no acid other than
carbonic is excreted by roots, but that decay of the roots does give a slight
increase in the alkalinity of the water. The author says "The problem is
important not only because acids dissolve plant food from the soil, but also
because it involves the fundamental questions of the reaction of protoplasm
and of the mechanism of excretion. " This is true, but to answer the question
in a way applicable to natural conditions one should not put them in the
abnormal conditions offered by distilled water. 21 One might also expect the
** Griffiths, David, Additional species of Opiuitia. Bull. Torr. Bot. Club 43 •
523~53L Pi- 30. 1916.
16 Pittier, Henry, Preliminary revision of the genus Inga. Contrib. U.S. Nat.
Herb. 18:173-223. pis. 81-10$. 1916.
*
,7 Rexdle, A.B., A new genus of Hydrocharidaceae. Jour. Botany S4'3 l 3~3 l6 '
pi. 545. 19 16.
18 Werxham, H. F., Tropical American Rubiaceae. VII. Jour. Botany 54-
322-334. 1916.
x » Wright, C. H., Diagnoses Africanae. LXIX. Kew Bull. 1916-.no. 9. p. 233.
20 Haas, A. R., The excretion of acids by roots. Proc. Nat. x\cad. Sci. 2 : 561-566.
1916.
*
21 True, R. H., The harmful action of distilled water. Amer. Jour. Bot. 1 : 255-
273- fii- i- I 9H-
1917] CURRENT LITERATURE 423
author to relate his work to the rather extensive work done on the differential
absorption of ions by plant structures and the resulting changes in the reaction
of the substratum. 22 This promises explanation of the corrosive action of
roots, their great power to absorb salts from soils, as well as their ability to
redden neutral litmus. On account of this process some method other than
that used by the author will probably need to be employed for investigating
acid secretion in natural growth conditions, in the presence of nutrient solu-
tions or soil. The value of this work as a basis for a general conclusion is
doubtful, considering that only two experiments were performed on a single
species, and these in an abnormal condition.— Wm. Crocker.
I
Subantarctic and New Zealand floras.— Skottsberg 23 has continued the
series of comparisons made between the floras of portions of the southern hemi-
sphere characterizing the previous work of Hooker, Diels, Schimper, Werth,
Cheeseman, and Chilton, and revising the list of bicentric types by taking
recent additions to the flora of Subantarctic America and New Zealand into
consideration. The list includes 49 orders. These may be referred to groups
' comprising (1) an Australian and New Zealand element in America, (2) an
Andine element in New Zealand and Australia, and (3) an old Antarctic element
which is more strictly bicentric. Of the last group Nothofagus is a striking
example, with 6 species in New Zealand, 1 in Tasmania, 1 in Tasmania and
New South Wales, 1 in New South Wales, and 8 in Chili with 3 extending to
Fuegia.
He includes some recent evidence from fossil plants found in Graham
Land, and concludes that there existed an Antarctic Tertiary flora resembling
the present floras of Subantarctic America, New Zealand, and Australia, and
that the Antarctic continent may have been a center of evolution from which
plants and animals wandered north. The present flora is due therefore to a
combination of old wanderings, the extinction of certain species during the Ice
Age, the survival of others, and finally transoceanic migrations, which, if they
ever took place, are still going on. — Geo. D. Fuller.
Subalpine plants of the Rocky Mountains.— Adding to a series of phyto-
geographical papers upon the Rocky Mountain region already noted, 2 *
Rydberg 2 * has analyzed the subalpine flora of the region. It consists of about
800 species, of which only 10 per cent are entirely restricted to the subalpine
zone. About 20 per cent of the whole number are transcontinental plants,
22 Skene, M., The acidity of Sphagnum and its relation to chalk and mineral salts.
Ann. Botany 29:65-87. 1915.
23 Skottsberg, Carl, Notes on the relations between the floras of Subantarctic
America and New Zealand. Plant World 18: 129-142. 1915-
24 Bot. Gaz. 62:83-84. 1916.
25 Rydberg, P. A., Phytogeographical notes on the Rocky Mountain region.
VI. Distribution of the subalpine plants. Bull. Torr. Bot. Club 43:343~3 6 4. 191 6
424 BOTANICAL GAZETTE [may
while another 20 per cent are found also in the Pacific mountains, leaving 60
per cent peculiar to the Rockies. Of these, fully one-half are restricted to the
southern Rockies, and less than one-fourth to the northern Rockies. Of the
locally endemic species, which are all herbaceous, 6 are confined to the Cana-
dian Rockies, 3 to Montana, 3 to Idaho, 14 to Wyoming, 13 to Utah, and 16 to
Colorado. Viola biflora is noted as having the most remarkable distribution,
having been found only in a few places in Colorado, in Alaska, and in Europe. —
Geo. D. Fuller.
A polycotyledonous bean. — Harris 26 has secured a race of the common
garden bean which shows steadily more than 2 cotyledons as tested by 3 off-
spring generations, comprising thousands of individuals. Since the race appears
in a "pure line'' and has remained constant in several differential features,
he concludes that its origin and behavior are characteristic of mutation as
defined by DeVries. The cotyledons are highly variable in number, ranging
from 2 to 7, but have a modal frequency of 4. For this reason the embryo
is described as tetracotyledonous. This persistent tendency of a dicotyle-
donous type to develop polycotyledony is an interesting confirmation of the
claim that the number of cotyledons developed depends upon conditions rather
than upon inevitable inheritance. — J. M. C.
Illinois Academy. — The volume of Transactions of the Illinois Academy
of Science for 191 5 has just appeared. It contains the following botanical
papers: Comparison of a Rocky Mountain grassland with the prairie of
Illinois, by George D. Fuller; Studies in Phyllosticta and Cercospera, by
Esther Young; Method of prophesying the life duration of seed, by James
E. Groves; Peculiar examples of plant distribution, by H. S. Pepoon; The
grass flora of Illinois, by Edna Mosher; A Florida smut, Ustilago sieglingiae,
in Illinois, by Margaret Mehlhop. A symposium on colloids includes the
following papers: Outline of the chemistry of colloids, by D. A. MacIxnes;
Significance of colloidal chemistry in physiology, by William Crocker. —
J. M. C.
Bog theories. — The vegetation of peat bogs exhibits such remarkable
peculiarities of habit and structure that it has called forth a number of varied
and somewhat conflicting explanatory theories. These theories have been
summarized carefully by Rigg, 27 especially in so far as the xerophily of the
plants is concerned, in a manner that is likely to prove very useful. A good
bibliography adds to the value of the paper. — Geo. D. Fuller.
^Harris, J. Arthur, A tetracotyledonous race of Phaseolns vulgaris. Mem
N.Y. Bot. Gard. 6:229-244. 1916.
27 Rigg, G. B., A summary of bog theories. Plant World 19:310-325. 1916.
VOLUME LXIII
NUMBER 6
THE
Botanical Gazette
JUNE iqij
development of dumontia FILIFORMIS 1
II. DEVELOPMENT OF SEXUAL PLANTS AND GENERAL
DISCUSSION OF RESULTS*
Grace A. Dunn
(with plates xix-xxii and seven figures)
Introduction
y Dumontia filiformis (Huds.) Grev. is a red seaweed which is
widely scattered in the temperate zones. It has been reported
as occurring on the Auckland and Falkland Islands (2), on the
shores of Alaska, and is very common in northern Europe. This
species was first found on the Atlantic coast of North America, by
the writer, at South Harpswell, Maine, in June 1913. Tetrasporic
i and cystocarpic plants were collected at that time. Sterile plants
were collected by Thaxter at Kittery Point, Maine, in April 1914 3
These are the only two points on this coast where plants of
Dumontia have been reported to occur.
In all probability Dumontia has become established on the coast
at South Harpswell some time between 1909-1913. F. S. Collins
collected at South Harpswell in the early part of July for 6 years
(1902-1905 and 1908-1909) in the same pools in which Dumontia
was abundant in July 1913 and 1914. He states that he has never
found a single specimen of Dumontia in any of these pools, and if
1 Botanical contribution from the Johns Hopkins University, no. 55.
2 First paper entitled "The development of the tetraspores." Plant World,
I 19: 271-281. figs. 2. 1916.
3 Personal letter from F. S. Collins.
42
426 BOTANICAL GAZETTE [june
the plants were then present they must have been extremely
scarce. The plants were very abundant in the early part of July
1913. If a few solitary plants were present in 1909, it is apparent
that they must have multiplied rapidly in the following 4 years.
It is highly improbable, therefore, that any plants of Dumontia
were present at South Harpswell as early as 1905.
Greville (i) in 1830 described fructifications which he had
observed in Dumontia filiformis. These fructifications were at-
tached to the inner surface of the wall of the thallus and consisted
of "clusters of large ovate seeds." It is evident from Greville's
description and figures that these "seeds" were carpospores.
Kutzing (5) published illustrations and a very brief description of
the tetraspores. Harvey (2) pictures a group of carpospores and
states that "clustered spores are common." Thuret (17) refers
to the antheridia of Dumontia, so at that time these bodies were
known to exist. The writer has not been able to find any descrip-
tion of the antheridia. All the papers published on the red algae
previous to 1883 dealt chiefly with the distribution and seasonal
occurrence of the various genera and the gross morphology of the
individuals. Schmitz's (13) paper in 1883 marks a greater step
in advance in the study of the red algae than has since been made
by any one investigator. Although his descriptions are not
complete, his general conception of the structure of the female
reproductive organs of Dudresnaya, Gloeosiphonia, and other
members of the Cryptonemiales is essentially correct in regard
to the cell history. His observations on Dudresnaya, Polyides,
and Petrocelis concerning the behavior of the nuclei in the
ooblastema filaments and auxiliary cells are correct. In Gloeo-
siphonia and some other genera Schmitz reports that the nucleus in
the cell which forms the carpospores is the product of two fusions.
The structure of the female reproductive organs of the red algae is
quite complicated. The auxiliary cell, the cell which produces the
carpospores, in nearly all the genera is formed by the fusion of the
cytoplasm of two or more cells. The behavior of the nuclei in these
cells fusing to form the auxiliary cell proved to be a stumbling block
to Schmitz and many other workers, some of whom regarded the
nucleus in this cell as the product of as many as 6 fusions (Haupt-
7
1917] DUNN—DUMONTIA 427
fleisch 4). The next epoch making paper in the study of the red
algae was that by Oltmanns (9). Oltmanns worked out very
carefully and in much detail the nuclear and cell history during
fertilization and carpospore formation in Dudresnaya, Gloeosiphonia,
and Dasya. Oltmanns' chief contribution was the convincing
evidence that the nucleus functioning in the auxiliary cell at the
time of the formation of the carpospores is a descendant of the
fusion nucleus in the carpogonium, and that no other nuclear
fusion has occurred. Oltmanns' descriptions are detailed and his
illustrations are remarkably clear, but nevertheless some present
day botanists question his observations concerning the absence of
a fusion between the nucleus in the auxiliary cell and that nucleus
which enters it from the sporogenous filament. These botanists
are inclined to believe that in the members of the Crytonemiales, as
in certain of the Ascomycetes, there are two nuclear fusions at the
time of fertilization. Dumontia and Dudresnaya belong to the
same family, Dumontiaceae, and it is to be expected therefore
that the two genera will have similar reproductive organs. In
view of the fact that Oltmanns' results have been questioned by
some workers, the present investigation of Dumontia filiformis
was undertaken for the purpose of gaining all possible information
concerning the behavior of the nuclei during fertilization and the
formation of the carpospores. It was also desired to gain informa-
tion concerning the general structure of this alga, the cytology
of its tetraspores, and the structure of its male reproductive
organs.
This study was begun in June 19 13, at the Harps well Labora-
tory, South Harpswell, Maine, where the plants were abundant.
It was continued during 1913, 1914, and 1915 at South Harpswell
and at Johns Hopkins University.
The writer wishes to thank Professor J. S. Kingsley for the
privileges of the Harpswell Laboratory, and also Dr. M. A. Howe
and Mr. F. S. Collins for identifying this alga. This investigation
was undertaken at the suggestion of Professor D. S. Johnson,
under whose directions it has been carried out, and whose criticisms
have been a constant source of aid. Dr. W. D. Hoyt also has
kindly examined many of the preparations.
428 BOTANICAL GAZETTE [june
Methods
Plants of this alga, either whole or cut into lengths of 5-10 mm.
each, were fixed in medium chromo-acetic solution, or in Flemming's
fluid, within a few minutes after being collected. As the alga is
very gelatinous, great care was taken that all changes in the alcohols
should be made very gradually. The material on which the alcohol
was changed in 5 per cent grades showed considerably less shrinkage
than that on w r hich the changes were made in 10 per cent grades.
Most of the paraffin sections used were 10 or 12 /x thick. Sections
2 /x thick were also used for cytological details. For staining,
Heidenhain's iron alum hematoxylin (1 hour in alum solution,
2 hours in hematoxylin) gave the best results. Acid fuchsin and
methyl green stained the spores very well, but were not satisfactory
for the vegetative structure. The triple stain, safranin, gentian-
violet, and orange G, was also used. The slipping from the slide
of sections of material fixed in Flemming's fluid occurred somewhat
frequently in consequence of bleaching the sections in hydrogen
peroxide. This difficulty was finally largely overcome by dipping
the slides into 0.5 per cent solution of celloidin in a mixture of
equal parts of alcohol and ether.
Description
HABITAT AND APPEARANCE
Dumontia, at South Harpswell, grows in abundance in tufts in
the small tide pools and also on the rocks that are exposed to the
air at low water. On large round rocks which were much exposed
to the surf, female and tetrasporic plants of Dumontia were found
growing down almost to the lower limit reached by Chondrus
crispus, that is, just below the mean low water level. There is
considerable variation in the size of the plants. The larger plants
were found in the more exposed places. The plants in the tide
pools near the low water mark were larger than the plants in the
higher pools, and the largest plants of all were those growing at low
levels on the round rocks. The color of the plants varies from a
rich dark red to a pale reddish yellow. Mature tetrasporic and
female plants ranged in height from 4 cm. to 23 cm. There is
1917]
D UNN—D UMON TIA
429
apparently no regular or constant system of branching, and the
number of branches present is not related to the height of the
plant (figs. 1-7). The plants shown in figs. 1 and 2 have almost
\
r
2
1
Figs. 1-3. — Mature female plants showing cystocarps imbedded in thallus
the same number of branches, and their respective heights are
cm
cystocarpic
which were 12 cm. in height and
■"
43°
BOTANICAL GAZETTE
[tune
were unbranched
female
maximum size before the carpo
iveraee size of the female plants
*
Figs. 4, 5- — Mature tetrasporic plants branched and unbranched showing fraying
out of thallus at apices of branches and main axis; Xo.6.
same as that of the mature cystocarpic plants collected in June.
Some of these plants collected in April bore only young carpog<
branches, while others bore mature
of this type
and
1917]
D UXN—DUMON TIA
431
auxiliary cell apparatuses in the upper portion of their thalli.
Carpogonial branches therefore were probably initiated on these
plants only a few days before they were collected. The average
Fig. 6.— Tetrasporic plant showing much inflated main axis and branches; Xo. 5
size of the male is less than that of the female plants. The maxi-
mum height of the male plants examined was 20 cm. They could
be distinguished from the young female plants only by microscopical
-
432
BOTAXICAL GAZETTE
[JUNE
examination. Female plants bearing mature cystocarps can readily
be distinguished from the male and tetrasporic plants because the
cystocarps form protrusions in the wall of the thallus (figs. 1-3).
%
Fig. 7. — Tetrasporic plant showing large number of much twisted branches; Xo . 4
The ends of the majority of plants collected in June and July were
considerably frayed out (figs, i, 3, 4, 6). Since growth is apical,
the branches cannot increase greatly in length after the fraying
has begun.
1917] DUNN— DUMONTIA 433
Lewis (8) has shown that the sexual and asexual generations
in most of the Florideae at Woods Hole differ physiologically, but
are identical in vegetative structure, chromosome number of course
excepted. These two generations in many forms appear at dif-
ferent seasons and have a tendency to grow on different kinds of
substrata. The plants shown in figs. 2 and 5 are fair examples
of well developed cystocarpic and tetrasporic plants of Dumontia
filiformis. It is evident from a comparison of these plants that
in this species also the two generations are morphologically almost
identical. The tetrasporic and cystocarpic plants of Dumontia, so
far as substrata on which they grow are concerned, appear to be
physiologically identical also. The two kinds of plants grow
together on all the large rocks and in most of the tide pools. The
tetrasporic plants were more abundant on 'the whole than the
cystocarpic ones, and a few pools contained only the former. These
tide pools, however, were in every instance within 3 or 4 feet of
apparently similar pools on the same level, in which both kinds of
plants grew. The temperature of the water was taken in a number
of the pools. It was found that the temperature of pools in the
same vicinity did not vary more than 2 C. This difference
existed between pools which contained tetrasporic plants only,
as well as between these and those pools in which both kinds of
plants were present.
SEASONAL OCCURRENCE
Male and young female plants of Dumontia were collected in
the latter part of April 1914 and on April 12, 1915. An unsuccess-
ful search was made for plants in January 19 14. It is believed
that the plants were not then present. The ratio of female to male
plants in the collection made in April 19 14 could not be determined,
owing to the fact that the plants when examined were considerably
broken up. The ratio of female to male plants in the collection of
April 12, 1915, was 3 to 1. This ratio is based upon the examination
of 24 plants collected from several different tide pools. Another
collection of plants was made on April 26, 1915, and of these plants
24 were examined, all of which proved to be female. Of these 24
plants 10 bore only carpogonial and auxiliary cell branches, while
14 bore chiefly young cystocarps and auxiliary cell branches.
r
434 BOTAXICAL GAZETTE [june
>
There were a few plants in the collection made on April 12 which
bore no reproductive organs; these were probably female plants
in which the carpogonial branches had not yet been initiated. All
of the plants over 4 cm. in height, collected in June and July, with
the exception of 2 or 3 individuals bearing carpogonial branches,
bore either mature cystocarps or tetraspores. Hundreds of plants
were collected and a careful but entirely unsuccessful search was
made for individuals bearing spermatia. It seems evident from
these facts that the male plants are present for only 2 or 3 weeks in
April. It is possible, of course, that a few solitary individuals
were present in June and July. This view is supported by the fact
that it was possible to find on the female plants collected during
this time all stages from the 1 -celled carpogonial branch to the
mature cystocarps. The cystocarpic plants reach their maximum
development in the early part of June and have completely dis-
appeared by the middle of July. The tetrasporic plants attain
their maximum development in the latter part of June, although j
plants 19 cm. in height were very abundant as early as June 12.
A few tetrasporic plants persist until late in August, but they are
rare even in the latter part of July. The tetrasporic and female
plants in all the red algae seem to be more numerous than the male
plants. The experiments of Lewis (7) with Griffithsia Bometiana
and Dasya elegans indicate that in both of these species the tetra-
spores form equal numbers of male and female plants. This is
probably true of Dumontia and other members of the Florideae.
The apparent scarcity of male plants may be due to the fact
that in some forms they are exceedingly small and therefore
are easily overlooked. This would not apply to such forms as
Dumontia, however, in which the difference in the average height
of the male and female plants is not more than 4-5 cm. Svedelius
(14, 16) reports that the male plants of Martensia and Delesseria
die shortly after they have discharged their spermatia. This is
probably true of the Dumontia plants also. Lewis (8) has found
that the tetrasporic plants of most of the red algae at Woods Hole
are very abundant in July. The tetraspores germinate to form
cystocarpic plants from which carpospores are released in Sep-
tember. The holdfasts of young sporelings formed from these
1917] DUNN—DUMONTIA 435
carpospores persist through the winter. These holdfasts, in the
following June, produce adventitious shoots which develop into
tetrasporic plants. Lewis believes that this is in general the
many
also exceptions to the separation in point of time of the two
generations. This separation is never of a perfectly sharp and
definite character, as the generations always overlap to a certain
midsummer
May and J
t South Harpswell is evidently
mentioned. The carpospores
Tune and July. This
from the fact that the carpospores
escaDiner from the cvstocarn. also t
plants 3-7 cm. in height were often found growing beside the stumps
of the frayed off cystocarpic plants. Germination of the tetraspores
has not been seen, but the occurrence of only male and female
in
through the winter in the form of sporelings derived from the
tetraspores discharged in June and July.
VEGETATIVE STRUCTURE
The holdfast of Dumontia is a platelike body composed of a single
filaments
ing, vertical branch (figs. 8, 9) . These vertical branches are closely
packed together, averaging about 12 cells in length, and are very
regular in form and arrangement. They are generally dichoto-
mously branched. The cells of the horizontal filaments usually
form no descending
branches. The few branches of this character
observed consisted of only one cell (fig. 8). It is evident from the
arrangement
they develop by apical growth.
form
the upright portion of this alga (fig. 9). In such longitudinal fila-
ments there is a gradual increase in the length of the cells. They
are closely packed together at the base of the main axis, forming
a solid tissue (fig. 9). At about o . 1
mm
436 BOTANICAL GAZETTE [june
j
longitudinal filaments or medullary hyphae separate, forming a
cavity which extends nearly to the tip of the plant. The thallus
of the plant is thus tubular in structure. The wall consists of 3
tissue layers. The inner layer is composed of 3 or 4 vertical rows
of medullary hyphae. Each cell of a medullary hypha produces
a radial branch. These radial rows of cells by repeated dichotomous
branching, in planes parallel and perpendicular to the surface of
the thallus, form the subcortex and the cortex (fig. 10). A branch
arising from a cell of a medullary hypha terminates in 64-128
cortical cells. The cells in the inner subcortex are not closely
packed together. The number of cells in a given area increases
as a result of the repeated branching, and thus a compact cortex is
formed. The 4 figures for each cell type in the following table
indicate the two diameters of the cell as seen in a longitudinal
section of the thallus, also the diameters of the nucleus and
nucleolus.
Medullary hyphae 5 2 ■ 2 /* 8.7/x, 2.7/x 1 .0 /1
Larger subcortical cells 315" 21.5" 2.7" 1 .0 "
Smaller subcortical cells . . . . 1 1 . 2 u 9 . 1 u 1.8" 0.8"
Cortical cells 8.4 " 7.0 u 2.8 u 1.4"
In addition to the radial branches forming the subcortex and
cortex, the medullary hyphae may give rise to other branches which
remain axial and thus form longitudinal filaments. The medullary
hyphae at the tips of the branches and the main axis terminate in a
number of short branches composed of small cells (fig. n). No
single initial cell could be recognized at the apex of any branch
in Dumontia. Branches varying in length from 2 mm. to 4 cm.
were examined. The structure of the apex of a branch of Dumontia
appears to be similar to that of Furcellaria (Wille 18). Fur eel-
laria is cited by both Wille and Oltmanns as a good illustration of
the " Spring-brunnen " type of vegetative structure (Oltmanns 9).
The holdfast of Dumontia also resembles that of Furcellaria.
Each of the medullary hyphae in Dumontia, as well as each of the
lateral branches arising from these hyphae, has its own initial cell.
Practically all the vegetative cells of Dumontia are uninucleate.
chromatin
All
»
the vegetative cells in the thallus, with the possible exception of a
1917] DUNN—DUMONTIA 437
few cells in the lower layers of the holdfast, contain but one chroma-
tophore. The chroma tophore is a clathrate hollow ellipsoid lying
just inside the cell wall (fig. 12). It is similar to the peripheral
portion of the chromatophore figured by Wolfe (19) in Nemalion.
The chromatophore in some cells was seen to be enveloped by a
thin layer of cytoplasm in the form of a coarse net. This cyto-
plasmic envelope, although not always visible, was undoubtedly
present in all the cells.
Intercellular connections, such as are characteristic of the
Florideae, are present between all the vegetative cells and all the
sexual reproductive cells, including the carpospores, until they are
almost mature. At each intercellular connection there are two
similar disks joined by an apparently homogeneous strand of
cytoplasm. The cytoplasm appears to penetrate these disks, but
the matter has not been thoroughly investigated. The disks
stain readily with hematoxylin, and in some cells appear to be
composed of granules (fig. 13). One case was seen in which a
strand of cytoplasm 4 n wide connects two carpospores 22 n in
diameter (fig. 14). In this strand of cytoplasm are several granules
having an average length of o . 7 /x. These granules stain with the
same intensity as the disks. It is probable that these granules
would collect together to form the two disks when the strand of
cytoplasm has assumed its normal size. Trichomes are found on
all parts of the surface of the thallus. They seem to be most
numerous at the base of the frond. They are present on the male,
female, and tetrasporic plants. The trichomes are very abundant
on the young plants collected in April.
SPERMATIA
Definition. —If the following discussion is to be intelligible, it
will be necessary to define the terms which will be used in the
description of the male reproductive organs. Those cells which are
analogous to the sperms of the green and brown algae will be
designated as spermatia. Yamanouchi (20), writing of Poly-
siphonia, calls these cells sperms, but "spermatia" is the term
which has been most widely used by workers on the red algae and
is therefore to be preferred.
43§ BOTANICAL GAZETTE [june
Schmitz (13) , Wolfe (19), and some other workers on the red
algae have found that the spermatium is sometimes discharged as
a naked protoplast. Svedelius* (14) therefore maintains that a
distinction should be made between the free spermatium, the naked
protoplast, and this same protoplast inclosed in a cell wall as it is
when attached to the parent plant. He refers to the protoplast
inclosed in the cell wall as the "spermatangium." The cell which
Svedelius refers to as the " spermatangium mother cell" is anal-
ogous to the " spermatium mother cell" of Nemalion (Wolfe 19).
, Spermatium mother cells. — The spermatium mother cells of
Dumontia filiformis are homologous to the outer cortical cells of
the tetrasporic and cystocarpic plants. In a mature male plant
of Dumontia almost all the outer layer of cells of all the branches
and of the entire main axis from about 1 cm. above the holdfast
consists of spermatia and their mother cells. The outer cortical
cells of the main axis just above the holdfast are similar to those
of the tetrasporic and cystocarpic plants. Although the distribu-
tion and position of the spermatium mother cells on the individuals
of the different genera varies considerably, no other form has been
reported in which they form a continuous layer over almost the
entire thallus as they do in Dumontia. Each stalk cell in Dumontia
bears at least two and probably more spermatium mother cells
(tig. 15). The spermatium mother cell may bear two spermatia,
just as it does in Polysiphonia (Yamanouchi 20), Martensia
(Svedelius 14), and Delesseria (Svedelius 16).
A distinct chromatophore is certainly present in the stalk cell
of the spermatium mother cell of Dumontia filiformis (fig. 15)*
A chromatophore is occasionally seen at the base of a spermatium
mother cell borne on one of these stalk cells. The upper part of
such a mother cell contains only granular cytoplasm (fig. 19)-
Many of the mother cells contain only cytoplasm and no chromato-
phores (fig. 15, first cell to right). Although it was not visible, a
net of cytoplasm is undoubtedly present in the stalk cells as it is
in all the vegetative cells of Dumontia. When the spermatium
mother cell was first formed, it must have contained a chromato-
phore which had been cut oflf from that in the stalk cell. A large
portion of the granular cytoplasm in the spermatium mother cell
1 9 1 7 1 D UNN—D UMON T1A
439
was probably present originally in the chroma tophore. The
chroma t
more
for examination. However, even in the preserved material it
should be possible to distinguish the chromatophores from the
cytoplasm. The protoplasm of the chromatophores is apparently
homogeneous; they contain no visible vacuoles and have a definite
outline. Many spermatium mother cells were seen which showed
intermediate stages in the disappearance of the chromatophore and
the formation of the granular cytoplasm (fig. i
Osterhout (n) states that a reduced chromatophore is present
in the young spermatium of Batrachospermum. This chromato-
phore disappears when the young spermatium matures. Wolfe
(19) observed the division of the chromatophore in the spermatium
mother cell of Nemalion in Dreuaration for the formation of the
spermatium
time
spermatium and then disappears. Immediately after its disap-
pearance a mass of deep staining cytoplasm is seen at one end
permatium. Wolfe
permatia
cytoplasm has been derived from the pro topi
phore. No other workers, with the possibl
nouchi, have seen chromatophores in the
mother cells. Yamanouchi (20) states that the sperm mother
cells contain fine granular cytoplasm and generally no plastids.
Chromatophores are present in all the genera, either in the imme-
diate or somewhat remote ancestors of the spermatium mother
cells. Svedelius (14) states that he did not actually observe the
disappearance of chromatophores in Martensia, but he believes
that the protoplasm in the chromatophores of certain cells is used
in forming the granular cytoplasm of their daughters which do not
contain any chromatophores.
Spermatid. — No stages were seen showing a uninucleate sper-
matium mother cell. This cell in the earliest stages observed is
binucleate (fig. 16). The first spermatium is cut off obliquely
(tigs. 15, 17, 19). The mother cell than elongates, again becomes
binucleate (fig. 17), and a second spermatium is cut off. Many
spermatia were seen in the swollen gelatinous sheath enveloping
440 BOTAXICAL GAZETTE [june
the thallus and some which had actually reached the exterior
(fig. 1 8). Every spermatium seen outside the parent plant is
inclosed in a cell wall (fig. 41). No empty cell walls were seen
attached to the spermatium mother cell. Many spermatia were
seen lying close to the mother cells, but not attached to them (fig.
19). The spermatia in Dumontia are apparently cut off from the
mother cell in the same manner as they are in Polysiphohia (Yama-
nouchi 20). The wall of the spermatium in both of these genera is
a portion of the wall of the spermatium mother cell, and no body is
formed which would be homologous to the spermatangium of
Deles seria (Svedelius 16). Svedeuus (14) believes that the
spermatia in Martensia are set free in the same way as they are in
P oly si phonia . Lewis (6) states that in Griffithsia the spermatia
are cut off from the mother cells. This form can hardly be com-
pared with those previously mentioned, because in Griffithsia none
of the cells of the antheridial filament form cellulose walls, but ail
are imbedded in the swollen wall of the mother cell of the branch.
The spermatia of Dumontia, as far as their contents are con-
cerned, are similar to most of those which have been described in
the other genera. The cytoplasm is much vacuolated at the
proximal end of the spermatium and is very dense at the distal
end. It is difficult to determine the structure of the nucleus,
because it is situated at the distal end of the spermatium, imbedded
in the dense, deep-staining cytoplasm. All the chromatin appears
to be in the nucleolus or in several chromatin granules collected
in the center of the nucleus (figs. 17, 10).
CARPOGONIAL BRANCHES
Nearly all the carpogonial branches found in the mature female
plants were between the levels of 7 .5 and 17.5 mm. from the hold-
fast. At levels higher up in the thallus, where mature cystocarps
occur, a few carpogonial branches are occasionally present. These
are not confined to one side of the thallus, but are scattered indis-
criminately among the cystocarps. Young cystocarpic plants
about 3 cm. in height were occasionally found even as late as July 5-
The few cystocarps which were present on these plants were at
the tips of the branches. Carpogonial branches were found in the
1917] DUNN—DUMOXTIA 441
lower portions of the branches and in the main axis. The carpo-
gonial branches in Dumontia evidently are not formed in acropetal
succession. The carpogonial branches arise from the lateral
branches of the medullary hyphae. They arise either from the
basal cells of these subcortical branches or from cells intermediate
in position between the medullary hyphae and the surface of the
thallus. On the young plants every second or third large sub-
cortical cell or occasionally each successive cell produces a carpo-
gonial branch. Radial branches arise from the intervening cells.
In mature plants, where carpogonial branches occur only at the
base of the thallus, they develop from every fourth, fifth, or sixth
cell. Sometimes the same cell will produce two carpogonial
branches or one carpogonial branch and one radial branch (fig. 20).
A mature carpogonial branch consists of 6 or 7 cells and a
*
trichogyne. If there are only 6 cells, they are all in a row. When
,the carpogonial branch is composed of 7 cells, one cell may be formed
as a lateral outgrowth of the basal cell. For convenience and
clearness the cells of the carpogonial branch will be numbered.
The basal cell which is attached to the vegetative cell will be
numbered 1, the cell above it 2, etc. The first cell of the carpo-
gonial branches arises as a conical protrusion of the subcortical cell
(fig. 21). A portion of the peripheral chromatophore of the latter
is cut off in this protrusion. This first cell is uninucleate (fig. 22),
and divides by a wall parallel to its base (fig. 23). The chromato-
phore in each of these young cells of the carpogonial branches is
always peripheral, as it is in all the vegetative cells. The second
cell next divides transversely, thus forming a 3-celled carpogonial
branch (fig. 24). No data were obtained concerning the details
of nuclear division in these earlier stages. This is due to the fact
that these stages persist for only a short time, and that the cells
are small and almost completely lined by the chroma tophores.
Considering the size and position of the cells in these young carpo-
gonial branches, it is evident that it must be the terminal cell which
divides each time. The cell wall separating the second and third
cells was barely visible in some carpogonial branches which had
just reached the 3-celled stage (fig. 24). These cells are separated
considerably at a slightly later stage (fig. 25). In the 4-celled stage
442 BOTANICAL GAZETTE [june
also the 2 terminal cells are at first in close contact, but later
become separated (fig. 26).
The cells of the carpogonial branch in the 4-celled stage may
lie in a straight line, or the axis of the 3 terminal cells may form
more or less of a right angle with that of the basal cell (figs. 27, 28).
The nuclei here furnish evidence to support the assumption that
the carpogonial branch develops by the repeated division of the
terminal cell. In several cases the nucleus of this cell is consider-
division
much more
carpogonial branch than in the younger branches (fig. 29). One
branch was observed in which the fifth cell, the terminal cell, was
binucleate (fig. 30). Each cell in a carpogonial branch until it
has reached the 5- or 6-celled stage generally contains one chromato-
phore. The one chromatophore then divides into a number of
small parts which are connected by strands of cytoplasm (fig. 31).
The structure and the arrangement of the cytoplasm and chroma-
tophores at this stage appear to be very similar to those in the
tetrasporangium
most
ma
same as that of those in the spermatium mother cells. The chroma-
time
contents of the cells increase.
chromato
phores is apparently used to form a part of the granular cytoplasm.
There are generally present 2 or 3 chromatophores in each of the
3 or 4 basal cells, even after fertilization, when the sporogenous
filaments are being formed (fig. 42). These chromatophores are
hollow ellipsoids, like those in the tetraspores, but unlike the latter
generally show no sign of being clathrate.
A large number of carpogonial branches were observed which
bore short stumps or fairly long pieces of trichogynes (figs. 32-38).
almost
hich
the thallus (figs. 35, 37). Other trichogynes were found \
jected beyond the surface of the thallus and which could be traced
back toward carpogonial branches (figs. 39, 40). Although no
carpogonial branch was found in which the trichogyne could be
traced from the carpogonium out beyond the surface of the thallus,
19 1 7l DUNN—DUMONTIA 443
it is evident that this is actually its course. The failure to obtain
a satisfactory section was due to the varying and indirect course
of the trichogyne. Though most of the sections examined were
12 /x thick, the trichogyne nearly always passed out of the section
and it was very difficult to locate it in the adjoining sections. The
trichogyne, just beyond its point of attachment to the carpogo-
nium, is often much coiled (figs. 34, 37, 40). The trichogyne is
always surrounded by a fairly thick gelatinous wall which is a
continuation of that of the carpogonium (figs. 34, 37). The
granular cytoplasmic content of the trichogyne stains with the
same intensity as does that of the terminal cells of the carpogoniai
branch. No structure was seen in any trichogyne which could
positively be identified as a nucleus. In a few cases a body was
seen which appeared to be similar to a nucleolus (fig. 39). This
body is surrounded by a light area, but not by a definite membrane,
and is therefore not thought to be a nucleus. There are present in
some of the trichogynes (fig. 37) 2 or 3 masses which, with hema-
toxylin, stain like chromatin. The question of the presence of a
nucleus in the trichogyne of the Florideae is still unsettled.
Svedelius reports that the trichogyne nucleus in Delesseria san-
guined disintegrates before fertilization and the chromatin granules
pass out into the cytoplasm. It is possible that some of the granules
seen in Dumontia and other forms are chromatin granules of similar
origin.
There are two types of mature carpogoniai branches. A cell
is sometimes formed as a lateral outgrowth of the basal cell of the
carpogoniai branch (fig. 35). The cell thus formed is a super-
numerary cell and will not be numbered, as it is not always present
and has no special function. This supernumerary cell has 1
been observed in a carpogoniai branch which is not mature,
basal cell of the carpogoniai branch is often found to be binucleate
(figs. 35, 38, 40) and sometimes contains as many as 3 nuclei (fig.
36). The basal cell is sometimes binucleate after having cut off
the supernumerary cell (fig. 35). It thus appears that there is a
tendencv of the basal cell to form a lateral branch. Also the third
The
some of the carpo
(figs- 33, 38). It is difficult to determine whether the nucleus in
444 BOTANICAL GAZETTE [juke
these cells has actually divided or has merely elongated. The
nuclei of cells i, 2, and 3 of the carpogonial branch are often not
in the resting condition, that is, all the chromatin is not in the
nucleolus. The chromatin in these nuclei may be in one body sur-
rounded by a number of small granules (fig. 32, cells i, 2; fig. 38,
cell 1), or in several small bodies (fig. 32, cell 3; fig. 36. cell 3; fig.
37, cell 3). The 3 terminal cells (4-6) are smaller than the first
3 or 4 cells and their nuclei are generally in the resting state. In
many of the Delesseriaceae and Ceramiaceae some of the cells of
the carpogonial branches contain two or more nuclei. The veg-
etative cells in these forms are multinucleate, and it is not surprising
f
that this nuclear condition should occur also in cells of the carpo-
gonial branches. In a form like Dumontia, where nearly all the
vegetative cells are uninucleate, it is surprising that any cells of
the carpogonial branch should contain more than one nucleus.
However, the cytoplasmic contents of the carpogonial cells are
much greater than those of the adjoining vegetative cells in propor-
tion to their size, and the presence of an extra amount of chromatin
in the larger cells of the carpogonial branches is quite in accord with
the current belief of a definite relation in volume between cell and
nucleus. The mature carpogonium lies close to or in contact with
the third cell (figs. 32-38).
Only 4 trichogynes with spermatia attached to them were
found in all the material examined. These were found in the
material collected in April 191 5. Although this number is small,
it is not less than would be expected, since only a very few tricho-
gynes were found projecting beyond the surface of the thallus.
This may have been due to the fact that the mature trichogynes
persist for only a short time, or that they are easily broken off.
It is to be regretted that none of these trichogynes with the sper-
matia attached to them could be traced back to the carpogonium.
In none of these cases was it possible to find even the carpogonium.
In one case one spermatium had fused with the tip of a trichogyne,
while 7 others were merely adhering to its sides (fig. 41). Judging
from the way it stained, the cytoplasm in this one spermatium
and in the tip of the trichogyne had begun to disintegrate. The
other spermatia stained very lightly, and it was not possible to
i
1917] DUNK—DUMONTIA 445
distinguish the structure of their contents. The cytoplasm in all
the trichogynes with the spermatia attached to them appeared to be
disintegrated, and no trace of a male nucleus was seen in any of
them. Disintegrating cytoplasm stains very deeply in vegetative
cells which have been injured, in trichogynes which have functioned,
in carpogonial branches which have not been fertilized but are
destined soon to disappear (fig. 36), and in those cells of the auxiliary
cell apparatuses which are terminal and will also soon disappear.
The cytoplasm of the trichogyne would not disintegrate as soon as
the male nucleus had entered it, so that this nucleus in all these
cases had probably passed into the carpogonium. Only one sper-
matium was attached to each of the other 3 trichogynes.
It has always been extremely difficult to obtain clear evidence
concerning the phenomenon of fertilization in the Florideae. A
few workers, as Oltmanns (9), Osterhout (ii), Hassencamp
(3), Wolfe (19), Yamanouchi (20), and Svedelrjs (16) have suc-
ceeded in finding consecutive stages showing the fusion of the
spermatium to the trichogyne, the passage of the male nucleus down
the latter, and the fusion of the male and female nuclei in the carpo-
gonium. The only two members of the Dumontiaceae in which
the structure of the female reproductive organs has been care-
fully worked out are Dudresnaya purpurifera and D. coccinea
(Oltmanns 9). Oltmanns in D. purpurifera observed the entrance
of the male nucleus into the trichogyne. The nucleus of the car-
pogonium at this time has moved out into the coiled portion
of the trichogyne. No nucleus is present in the trichogyne in the
next stage which he observed, but in the carpogonium there is a
nucleus which he assumes to be the fusion nucleus. Oltmaxns
states that he was not able to secure satisfactory evidence concern-
ing the fusion of the male and female nuclei. He does not describe
or picture fertilization in Dudresnaya coccinea, but states that it is
in no way unusual. In Dumontia less evidence has been obtained
concerning fertilization than Oltmanns presented in the discussion
of the two species of Dudresnaya. Nevertheless, there is really no
reason to doubt the occurrence of fertilization in these forms.
As previously stated, the mature carpogonial branch is always
bent around so that the carpogonium is close to or in actual contact
■■
446 BOTANICAL GAZETTE [june
with the third cell. In many cases it lies very close to the second
cell also. Thus the structure of the carpogonial branch suggests
that the fusion nucleus passes from the carpogonium into the sec-
ond or third cell. This evidently does occur, although satisfactory
stages showing the process have not been found. Such figures as
42 and 43 show that the sporogenous filaments originate from either
the second or third cells of the carpogonial branch. Since the
actual passage of the fusion nucleus into the cell producing the
sporogenous filaments has not been observed, there will naturally
arise a question concerning the origin of the nuclei in these filaments.
It cannot positively be stated that the nuclei in the sporogenous
filaments are descended from the fusion nucleus of the carpogonium,
but most of the evidence leads to this conclusion. Hundreds of car-
pogonial branches which have not been fertilized have been exam-
ined, and in only two or three cases is there any evidence that the
third cell is binucleate. The second cell has never been observed
to contain more than one nucleus. Oltmanns (9) states that in
Dudresnaya coccinea the cell of the carpogonial branch with which
the sporogenous filament fuses is often binucleate, but that these
nuclei never move out into the sporogenous filaments. Spermatia
are found fused to trichogynes projecting beyond the surface of the
thallus. Sporogenous filaments are found arising from cells of
carpogonial branches whose trichogynes probably had projected
beyond the surface of the thallus (fig. 42). The cells which produce
the sporogenous filaments are those which in other carpogonial
branches are always close to or in contact with the carpogonium.
Considering these facts it seems highly probable in Dumontia
filiformis, as in Dudresnaya purpurifera and D. coccinea, that the
nuclei in the sporogenous filaments are derived from the fusion
nucleus in the carpogonium. All the cells in the carpogonial
branches stain very faintly at the time of the formation of the
sporogenous filaments. The cytoplasm in all the cells, particularly
the terminal ones, becomes very thin (fig. 42) and in some cases
practically nothing but the cell walls is visible. The cytoplasm
in these cells is disintegrating, but not in the same manner as it
does in the trichogynes and some of the other cells. The failure
to find the carpogonium may be due to the fact that it disintegrates
I
1917] DUNN—DUMONTIA 447
after it has discharged its nucleus- The carpogonium is much
smaller than the cell which produces the sporogenous filaments,
m
the fusion of the two cells.
The sporogenous filaments in Dumontia, according to Schmitz
(13), grow out from the carpogonium and do not fuse with any cell
in the carpogonial branch. This statement obviously is not correct.
One cell of the carpogonial branch in Dumontia may produce three
sporogenous filaments (fig. 42). A mass of fairly dense cytoplasm
which always contains a nucleus and sometimes a chromatophore
is present at the tip of each filament (fig. 42). The remainder of
the filament appears to be entirely empty. The sporogenous
filaments in Dudresnaya purpurifera (Oltmanns 9) arise from the
carpogonium and do not fuse with any cell in the carpogonial
branch. A carpogonial branch in D. purpurifera and D. coccinea
-
produces 2 or 3 sporogenous filaments. Each of these filaments in
D. coccinea fuses with a cell of the carpogonial branch before grow-
ing out into the tissue of the thallus. All the cytoplasm in the
3 sporogenous filaments in D. purpurifera is derived from the carpo-
gonium, in D. coccinea from the carpogonium and 3 other cells of
the carpogonial branch, and in Dumontia from either the second
or third cell of the carpogonial branch.
AUXILIARY CELL BRANCHES
The auxiliary cell branches of Dumontia have the same origin
and the same distribution as the carpogonial branches, but they
are not so numerous as the latter. The ratio of carpogonial to
auxiliary cell branches, considering the average number of branches
initiated on a plant, is . approximately 7 to i. The carpogonial
branches are very numerous in certain regions, as at the base of
the mature cystocarpic plant. The auxiliary cell branches are
found to predominate over the carpogonial branches at slightly
higher level on this same plant.
The mature auxiliary cell branches vary in length from 4 to 6
cells (figs. 44, 45). The basal cell, just as in the carpogonial branch,
may cut off a supernumerary cell (figs. 43, 45> 4°)- Tne size oi
the cells and the mode of development of the auxiliary cell branch
448 BOTANICAL GAZETTE [june
similar
of the carpogonial branch. The
which could be distinguished from
sim
a carpogonial branch consists of 3 cells (fig. 47). The
of the two branches is very apparent. The terminal cell of the
auxiliary cell apparatus as a rule is not as pointed as that of the
carpogonial branch (compare figs. 44-53 vsrith figs. 24-28). There
are, however, exceptions to this rule (figs. 48, 54). This cell may
not be pointed even when it is about to divide (figs. 52, 53). There
is also some difference in the way in which the cytoplasm of the
cells of the two branches stains. This difference is so slight that
it can be used as a criterion in distinguishing the two kinds of
branches only when they are in one section or in sections which
have been similarly fixed and stained. The basal cell of the
auxiliary cell apparatus is often binucleate (fig. 50) and sometimes
contains 3 nuclei (fig. 48), as does the similar cell in the carpogonial
branch (fig. 36). None of the cells except the terminal one was
ever observed to be binucleate in a carpogonial branch which was
not mature. The auxiliary cell branch shown in fig. 49 is not
mature, and the second cell is binucleate. Fig. 50 shows an
immature branch in which 3 cells are binucleate. Some of the
cells in the auxiliary cell branches contain chromatophores similar
to those in the cells of the mature carpogonial branches and in the
sporogenous filaments (figs. 44, 55). The auxiliary cell is either
the second or third cell of the branch (figs. 43, 45, 57-60, 63).
The sporogenous filament with the nucleus in its end grows toward
the auxiliary cell branch (fig. 54).
The sporogenous filament fuses with the auxiliary cell (figs. 43 >
45 , 56, 59). Some of the cytoplasm of the sporogenous filament
undoubtedly fuses with that of the auxiliary cell. This appears
evident from the fact that the end of the sporogenous filament
always contains cytoplasm and in some cases terminates in the
auxiliary cell (figs. 45, 56, 59). After the fusion of the sporogenous
filament with the auxiliary cell, the original nucleus of the latter
maintains its former position (figs. 45, 60, 63) or withdraws to one
side (fig. 58) as in Dudresnaya purpurifera and D. coccinea. It has
been stated that cells 2 and 3 of the auxiliary cell branch are
occasionally binucleate. This binucleate condition in the auxiliary
19 1 7l DUNN—DUMONTIA 449
-
cell is apparently of no significance, because the nucleus from the
sporogenous filament enters here just as it does in the uninucleate
auxiliary cell (fig. 57). Oltmanns reports that the sporogenous
filaments in Dudresnaya purpurifera and D. coccinea branch freely.
These filaments in Dumontia apparently branch only occasionally
(figs. 42, 43). In both species of Dudresnaya no septa are formed
in the filaments except when they fuse with the auxiliary cells.
When the septa do occur, they are formed in the filament on both
sides of its point of fusion with the auxiliary cell. The tip of the
filament may then grow on to fuse with 2 or 3 more auxiliary cells.
In Dumontia only one case was observed in which a filament has
actually fused with an auxiliary cell and does not also terminate
in the cell (fig. 43). No septa were seen in this filament. A few
filaments growing over auxiliary cells were observed, but in these
cases there was no indication of any fusion (figs. 44, 53). The
sporogenous filament in fig. 43 branches just before it terminates
in the auxiliary cell.
CYSTOCARPS
rm
These
Carpospore development is initiated by the f<
or 4 gonimoblast filaments, of about 3 cells each, w
cessively from the lateral protrusion of the auxiliar^
filaments branch once, often twice, and every cell forms a spore
(figs. 56, 59). The cells at first are uninucleate (figs. 56, 58, 59, 63).
At a little later stage they become binucleate and divide (fig. 62).
No sterile cells are present at the base of the gonimoblast filaments.
The carpospores when first formed are rounded or subangular and
about 1 1 fx in diameter. They are well filled with a spoil
plasm which contains many small vacuoles (fig. 6$). No chroma-
tophores are visible, but often a number of small dark staining
granules are present. When the nucleus is in the resting state, all
the chromatin is in the nucleolus. In the young cystocarp there
are generally present 3 or 4 cells of the auxiliary cell branch (figs. 56.
as many as 5 (fig. 62). A portion of the
auxiliary cell branch is often present even in the mature cystocarp
(fig. 60). The wall of the cystocarp is formed by branches which
yto
sometimes
from
enlargement of the group of carpospores
450 BOTANICAL GAZETTE [june
The growth of these branches which form the pericarp is similar to
that of the ordinary subcortical branches.
On an average 9 carpospores are present in a median transverse
section of a mature cystocarp. Often 3 or 4 cystocarps will crowd
together, so that in a section they appear as one. The average
diameter of the mature carpospores is 38 /x. When the carpospores
are actually mature, they are well filled with cytoplasm, contain
a large amount of Floridean starch, and a number of protein gran-
ules. These granules respond to the stain and to the protein test
in the same way as those in the tetrasporangia. These protein
granules when they first appear are small and very numerous. In
one carpospore in a median section 12 /jl thick there are 170 of these
granules (fig. 64). The ringlike chroma tophores, about 2.5 /x in
diameter, first appear in the carpospore just before it is mature.
They are not peripheral but are scattered throughout the entire
protoplast. Chromatophores are often present in the sporogenous
filaments and in the auxiliary cells, but have never been seen in the
latter at the time the carpospores are formed. It is possible that
chromatophores which do not take the stain are present in these
cells, although it seems hardly probable that they could be com-
pletely overlooked, since the cytoplasm in the auxiliary cell is very
thin and much vacuolated. It is generally believed that chromato-
phores never arise de novo, and Schmitz (12) has stated that they
are always present in the spores of the Florideae. In other
Florideae besides Dumontia the chromatophores are evidently not
readily seen at this stage, since their presence in the young carpo-
spores is rarely mentioned.
The protein granules in the mature carpospores often disappear
just before the spores are discharged, and are never present in
the germinating spores. Certain of the chromatophores increase
greatly in their staining power coincident with the disappearance
of these granules (fig. 65) . There has evidently been some modifica-
tion in the substance of these chromatophores, and it seems quite
possible that the substance of the protein body is concerned with
this change. The chromatophores in the mature carpospores which
have thus become differentiated stain with the same intensity as
those in the germinating carpospores and appear to have the same
1917I DUNN—DUMONTIA 451
I
structure as those in the mature tetraspores. The majority of
carpospores in a mature cystocarp contain one large nucleus each
(fig. 66). Occasionally a spore which is just about to escape con-
tains 2 nuclei (fig. 67), The spore shown in fig. 67 was directly
behind a spore which was just passing through the pore in the wall
of the cystocarp. The fact that the nucleus divides in some of
these carpospores just as they are escaping indicates that the spores
germinate as soon as they are discharged. In fact, the spores
sometimes germinate while still inclosed in the cystocarp. In most
of the female plants collected, the tips of the main axis of the thal-
lus and branches were frayed out. The mature carpospores are
present at these points, and it is therefore evident that the dis-
integration of the cells surrounding them furnishes one possible
means of escape. As the carpospores enlarge, they compress the
surrounding vegetative cells on all sides, and also cause the wall
of the thallus to bulge out. The layers of cortical and subcortical
cells gradually become thinner on the bulging side of the pericarp,
until finally they are ruptured and the naked carpospores escape
through the pore thus formed (fig. 68, i).
Groups of multinucleate cells, which are of the same size and
have the same position as the normal cystocarps, occasionally
occur in the wall of the thallus. In group i, fig. 68, a section of a
normal cystocarp, 16 spores appear to be present, but probably
not all of these are in this one cystocarp. Similar sections of two
groups of multinucleate cells on the other side of the thallus (2
and 3) contain respectively 30 and 70 cells. Some of the cells in
the groups of multinucleate cells are uninucleate and of the same
size as the mature carpospores (fig. 66), while others of approxi-
mately the same size or smaller contain 2 or 3 nuclei (figs. 67, 69,
71). In some cases nuclear division is followed by cell division
(fig. 70). Evidently after one of these larger spores divides, the
daughters may in turn become multinucleate (fig. 71). From the
arrangement of some of the cells it appears as though the larger
cells have divided to form the smaller ones. The number of nuclei
in the cells of a cystocarp similar to group 3, fig. 86, does not seem
to be determined by the size of the cells. Some of the smaller
cells may contain as many as 1 1 nuclei and the larger ones only
452 BOTANICAL GAZETTE [jtjne
i or 2. These are certainly nuclei and not pyrenoids, since they
were clearly distinguished by hematoxylin, safranin, or methyl
green. Many of these cells are somewhat vacuolated, and none
of them contains protein granules or visible chroma tophores. No
cases have been observed in which any of these cells are escaping
from the cavity. It seems probable from all the evidence available
that such a group as 3 is formed by division of the spores of a normal
cystocarp, and 2 is an intermediate stage between 1 and 3. Each
of these groups of multinucleate cells, therefore, is the product of
an abnormal cystocarp.
Germination of the carpospores may begin long before they
escape from the thallus. The first step in germination is the forma-
tion of a gelatinous wall 2 \x thick (fig. 72). The chromatophores
in these spores were 3 /x in diameter and stained darkly. They are
similar in structure to those in the tetraspore, but are larger and
more openly clathrate (figs. 73, 74). The chromatophores are not
merely peripheral, but, as in the younger carpospores, are scattered
throughout the whole protoplast. The next step in germination
is the elongation of the spore until it becomes somewhat pear-
shaped (fig. 74). The nucleus then divides and the first cell wall
is formed perpendicular to the longitudinal axis of the carpospore
(fig- 75)- The narrow cell, as in the germinating spores of Fucus,
is destined to form the basal part of the young plant. Neither
growth nor cell division takes place as rapidly here as in the upper
cells. The next wall formed apparently divides the upper cell
obliquely (fig. 76). In a longitudinal section of an older sporeling
these two upper cells were divided into 9 cells and the lower cell
into 3 cells. All the cells of these germinating carpospores are
rich in cytoplasm and contain chromatophores- The maximum
size of the sporelings examined was 235 /x by 123 /x. In cavities
containing germinating carpospores traces of disintegrating cyto-
plasm and nuclei have been observed, showing that some of the
unicellular carpospores have degenerated.
CYTOLOGY
The nuclei in the auxiliary cell and the carpogonial branches are
the most satisfactory ones in the cystocarpic plants for the study of
/
I
1917] DUNN—DUMONTIA 453
mitosis, since they are considerably larger and divide more actively
than the vegetative nuclei. The cell history of these branches is
also of some aid in identifying stages in nuclear division. All the
chromatin in the nuclei of most of the young carpogonial branches
is in the nucleolus (figs. 22-30). This is true of the nuclei also in
cells 4, 5, and 6 of the mature branches (figs. 32-34, 37). The
nuclei in cells 1,2, and 3 of the mature carpogonial branches have
a tendency to divide. The failure to secure any stages of mitosis
in the nuclei of the cells of the young carpogonial branches is
probably due to the fact that these cells divide very rapidly. The
chromatin in the nuclei in most of the uninucleate cells of the mature
auxiliary cell branches is not in the nucleolus but in a number of
small granules (figs. 48, 51-55)- The nuclei in the cells of these
branches divide often (figs. 46, 48-50). The frequency of division
of these nuclei is probably due, as in the basal cells of the carpo-
gonial branch, to the fact that these cells are usually completely
Thus in the resting nuclei
asm
of the cells of the carpogonial branches, as in the tetraspores and
chromatin
The following changes are observed in the nuclei in prepara-
tion for division. Radial fibrillae appear running from the nucleolus .
to the nuclear membrane (cell 2, fig. 55) . Small chromatin granules
pass out from the nucleolus, along the fibrillae, to the nuclear
■
membrane. When the granules first appear on the linin strands,
there is no appreciable decrease in the size of the nucleolus. The
position of these granules when they first appear indicates that
they have come from the nucleolus. Of the 6 granules present
in fig. 77, 3 are in contact with the nucleolus, and only i has yet
reached the periphery of the nucleolus. Nearly all of the granules
at a slightly later stage are present only at the points where the
fibrillae terminate in the nuclear membrane (fig. 78). More linin
strands are formed which connect the radial fibrillae already
present (fig. 79). All of the chromatin evidently passes out of
becomes
a thp linin net. The
net disappears just before the nucleus divides (fig. 80). Practically
all of the chromatin in the nuclei which have just divided is in 7
fairly uniform granules (cell 4, fig. 52). The nucleus of cell 4,
454 BOTANICAL GAZETTE [juxe
fig- 53? * s evidently just dividing. All of the chromatin in the
nucleus of this cell is in 14 granules of approximately the same size.
Nuclei which are probably preparing for division often contain 7
similar chromatin bodies (cell 3, fig. 51; cell 4, fig. 55; fig. 81).
It is thought that the chromatin bodies in these nuclei may be
chromosomes. Nuclei in the earlier stages of division contain
16-24 granules (cells 1 and 3, fig. 52; figs. 79, 80). These granules
must become grouped together to form the chromosomes. Thus
possibly the haploid number of chromosomes in Dumontia is 7.
However, it is evident that not enough data have been accumulated
to determine with any degree of certainty the number of chromo-
somes. These larger chromatin bodies in some of the nuclei are
vacuolated (cell 3, fig. 51). Ail the chromatin in the resting nucleus
is in the nucleolus, hence the chromosomes must fuse together after
division. It is quite possible that ail the chromosomes do not fuse
at one time. Thus in fig. 82 each of the 2 large chromatin bodies
in the nucleus which contains 5 may have been formed by 2 chromo-
somes fusing together. If the fusing continued, the nucleus would
appear quite similar to that in the adjoining cell. When the nucleus
is being organized after division, the nucleolus appears granular,
and a few small chromatin bodies may, for a time, remain outside
of it (fig. 62). In the nucleus of the mature carpospore the linin
net is well developed, and all the chromatin is in the nucleolus,
which always contains at least one vacuole (fig. 66). Our knowl-
edge of the details of mitosis in this species of Dumontia is as yet
very fragmentary. The stage represented in cell 3, fig. 52, * s
similar to the prophase of Delesseria as described by Svedelius
(15). This cannot be the prophase in Dumontia because the
granules present at this stage collect together to form larger units,
probably chromosomes.
In Poly sip honia (Yamanouchi 20) and Delesseria (Svedelius
15) the chromatin from which the chromosomes are formed is
never contained in the nucleolus. It is distributed in fine granules
along the linin threads. The granules are in groups or short rows,
each one of which represents a prochromosome. A chromosome
is then formed by the fusion of several granules. Mitosis in
Dumontia up to the time of chromosome formation seems to be
I
1917] DUNN—DUMONTIA 455
t
exactly similar to that in Nemalion (Wolfe 19). Nearly all the
chromatin in the resting nucleus of Dumontia is in the nucleolus,
and, as in Nemalion and Griffithsia (Lewis 6), this chromatin passes
out along the fibrillae to the periphery of the nucleus. The number
of granules present in Griffithsia and Nemalion seems to be about
twice the number of chromosomes formed. This may be the case
in Dumontia also, although in this form the number of granules
*
seems proportionately larger. There is no indication of any chro-
matin being expelled from the nucleus of Dumontia as it is in
Griffithsia .
Discussion and results
The auxiliary cell branch and carpogonial branch of Dumontia
filijormis resemble each other very closely in origin, mode of develop-
ment, and structure. This similarity is so great that in some cases
it is almost impossible to determine the character of a branch.
The number, arrangement, and contents of the cells may be the
same in these two kinds of branches. The trichogyne persists for
only a short time after it has functioned. Hence the absence of
*
this structure is not a safe criterion for distinguishing the auxiliary
cell branches. The carpogonial and auxiliary cell branches differ
greatly from the vegetative branches in the size and contents of
\
their cells. It seems quite possible that the auxiliary cell branches
in Dumontia once bore trichogynes and functioned as carpogonial
branches. This similarity in structure of the auxiliary cell and
carpogonial branches is almost as marked in Dumontia as in Du-
dresnaya coccinea. The auxiliary cell branch of D. coccinea consists
of 12 cells and the carpogonial branch of 7 cells (Oltmanns 9);
otherwise the two kinds of branches appear similar in origin and
structure and differ greatly from the vegetative branches.
It has been stated that the auxiliary cell branches and carpo-
gonial branches of Dumontia are probably homologous structures.
If this is true, the sporogenous filaments were probably developed
at the time when certain carpogonial branches ceased to be capable
of fertilization. The male plants in this species of Dumontia are
present for only 2 or 3 weeks during each spring. The ratio of
the number of female to male plants at the time when the latter
are supposed to be at the height of their development is 3 to 1.
456 BOTANICAL GAZETTE [june
An examination of scores of young female plants has shown that
the trichogynes must persist for only a short time after they have
reached the surface of the thallus. Under these conditions an
arrangement whereby the fertilization of one carpogonium would
make possible the development of 3-6 cystocarps would evidently
be of considerable advantage to the plant. If the auxiliary cell
branches are carpogonial branches which have ceased to function,
Dumontia presents a case quite parallel to that of Corallina. In
Corallina (Oltmanns 10) only those carpogonia in the center of the
conceptacle which bear long trichogynes are capable of being
fertilized. The carpogonia at the periphery of the conceptacle
cannot be fertilized because they bear no trichogynes. In each
conceptacle often only one carpogonium is fertilized. Descendants
of the fusion nucleus in this one carpogonium pass to the auxiliary
cells of many procarps, and several cystocarps develop in one
conceptacle.
Cell 2 or 3 of the carpogonial branch of Dumontia probably
functioned as the auxiliary cell before the plant had acquired
the habit of forming sporogenous filaments. It is cell 2 or 3 of
the auxiliary cell branch which forms the carpospores. One of the
3 cells in the carpogonial branch of Dudresnaya coccinea with which
the sporogenous filaments fuse, before passing to the auxiliary cell
branches, at one time probably functioned as the auxiliary cell.
The sporogenous filament often fuses with the fifth cell of the
carpogonial branch and with the fifth cell of the auxiliary cell
branch. In both Dumontia and Dudresnaya coccinea y therefore,
that which is supposed to have been the original auxiliary cell and
that which now functions as such occupy similar places in their
respective branches. The families of the Cryptonemiales show a
considerable variation in the distribution and structure of their
auxiliary cell and carpogonial branches. Even the species in one
genus as Dudresnaya (Oltmanns 9) may vary greatly in this respect.
It would then be rather surprising to find that the history of the
development of the auxiliary cells in all the Cryptonemiales is
similar. Oltmanns (9) suggests that the sporogenous filaments of
the Cryptonemiales have been developed from the gonimoblast
filaments of such forms as Wrangelia and Naccaria. He considers
1917] DUNN—DUMONTIA 457
t
f
Nemastoma the transitional form between the Nemalionales and
the Cryptonemiales. The auxiliary cells of Nemastoma do not
occur in special branches, but are modified cells of the cortical
hyphae. Thus in Nemastoma there are no auxiliary cell branches
which can be considered as homologous with the carpogonial
branches. But there is also the evidence which has been presented
1 that the auxiliary cell branches in some forms as in Dumontia are
I not vegetative hyphae which have by chance become highly special-
ized in the same manner as the carpogonial branches. Thus the
sporogenous filaments, structures which are peculiar to this one
order, the Cryptonemiales, have probably been developed along
two independent lines.
The female reproductive organs of the other red algae are
relatively simple when compared with those of the Cryptonemiales.
It is not surprising that the history of the nuclei in the sporogenous
filaments and auxiliary cells of the members of this order was an
especially puzzling problem to the earlier students. It has been
i
stated in the introduction to this paper that the origin of the nucleus
functioning in the auxiliary cells at the time of the formation of the
carpospores proved to be a stumbling block to most of these stu-
dents. The results of the work of Schmitz on certain genera of the
Cryptonemiales, including Dudresnaya, Dumontia, and Gloeosiphonia,
were conflicting in regard to the occurrence of a fusion between the
sporogenous and auxiliary ceil nuclei. Oltmanns' (9) investiga-
tion established practically beyond doubt the two following facts:
the sporogenous and auxiliary cell nuclei in Dudresnaya and
Gloeosiphonia do not fuse, and the nuclei in the carpospores are
descended from the sporogenous nucleus and not from the original
auxiliary cell nucleus.
No member of the Cryptonemiales has been carefully inves-
tigated since 1898 in regard to the occurrence of a nuclear fusion
in the auxiliary cell. A considerable amount of excellent work,
however, has been done on other red algae during the last 17 years.
The fusion nucleus or one of its daughters, in many genera, has
been traced from the carpogonium into the auxiliary cell. The
fusion nucleus in all these forms appears to take charge of the cyto-
plasm in the auxiliary cell and becomes the ancestor of the nuclei
458 BOTANICAL GAZETTE fc [june
in the carpospores. In none of these forms is the nucleus in the
auxiliary cell reported to fuse with the nucleus entering it from
the carpogonium. Thus Hassencamp (3), Yamanouchi (20),
Svedelius (14), and Lewis (6) have found, in the forms studied
by them, that only one nuclear fusion occurs during fertilization
and the formation of the carpospores, and this is the fusion between
the nucleus of the spermatium and that of the carpogonium. It
would seem that the evidence is overwhelming against the occur-
rence of a second fusion in the auxiliary cell. Undoubtedly one
reason why Oltmanns' work has been questioned is the fact that
certain morphologists have for years cherished the theory that
a relationship could be established between the Ascomycetes and
the Florideae. The ascogonium of certain genera is remarkably
similar in structure to the carpogonium of some of the Florideae.
No other plants except those belonging to these two classes have
this kind of a female reproductive organ. According to some
workers, certain genera of the Ascomycetes are distinguished
from all other plants by the fact that two distinct nuclear fusions
occur during fertilization and the formation of the spores. If it
could be shown that a second nuclear fusion does actually occur in
the auxiliary cell of such a form as Dudresnaya or Dumontia, the
carpogonium with its trichogyne and long sporogenous filaments
with the carpospores at their extremities might be proved to be
homologous with the ascogonium of some form like Pyronema with
its trichogyne and long ascogenous hyphae bearing ascospores.
It has been stated that in all probability the nuclei in the spo-
rogenous filaments of Dumontia are descended from the fusion
nucleus in the carpogonium. However, more evidence is to be
desired in regard to the origin of these nuclei. The sporogenous
nuclei in Dudresnaya purpurifera, D. coccinea, and Gloeosiphoma
(Oltmanns 9) are unquestionably derived from the fusion nucleus
in the carpogonium. In Dumontia, as in the 3 species of the Crypto-
nemiales studied by Oltmanns, there can be no doubt in regard
to the passage of a nucleus from a sporogenous filament into an
auxiliary cell. A nucleus is always present in Dumontia at the tip
of each filament. Tips of filaments are found lying quite near the
auxiliary cells. A similar filament is found fused to the auxiliary
1917] DUNN—DUMONTIA 459
/
f
cell, and no nucleus is then present in the filament. There are,
however, two widely separated nuclei in the auxiliary cell itself, and
one of these lies quite near the point of fusion of the filament and
the cell. The sporogenous nucleus in Dudresnaya pur pur if era , D.
coccinea, and Dumontia filiformis at no time even closely approaches
the original auxiliary cell nucleus. The 2 nuclei in all 3 species lie
at almost opposite ends of the cell. The carpospores are budded
off from that end of the auxiliary cell which contains the sporog-
enous nucleus. In Dumontia the original auxiliary cell nucleus
and the descendant of the sporogenous nucleus could be identified
in nearly all the auxiliary cells which bore carpospores. Oltmanns
(9) observed in Gloeosiphonia and Dudresnaya several cases of
" blind fusion" where, although a sporogenous filament had fused
with an auxiliary cell, no nucleus had passed over and the auxiliary
cell contained only its own nucleus. No examples of "blind fusion "
were found in Dumontia. It would seem that Oltmanns' state-
ment that it is a daughter of the sporogenous nucleus in Gloeosi-
phonia which moves into the pericentral cell might be questioned.
The two daughters of the auxiliary cell nucleus and the sporogenous
nucleus always lie close together. One of these 3 nuclei divides
and one of the daughters moves into the pericentral cell. In
Dudresnaya purpurifera, D. coccinea, and Dumontia there can be no
question as to the origin of the nuclei in the carpospore. They are
derived from the sporogenous nucleus.
Summary
Dumontia filiformis, during May, June, and the first half of
July, grows in abundance in the tide pools and on the bed rock at
South Harpswell, Maine. This alga became established on the
iouth Harpswell between 1905 and 19 13. Antheridial,
cystocarpic, am
size and vegetative structure. The average size of the antheridial
plants is a little less than that of the other plants. Cystocarpic
and tetrasporic plants are found growing together on the same rock
and in the same tide pools. Female plants which bear mature
cystocarps are easily recognized by the protrusions which these
orm
typ
460 BOTANICAL GAZETTE [june
considerably. All male and female plants collected were branched.
Tetrasporic plants, simple and branched, were found. The maxi-
mum number of branches observed on any individual plant was
30. The color of the plants varies from dark red to pale reddish
yellow. Male plants bearing mature spermatia are present in the
early part of April and two weeks later have almost completely
disappeared. Young female plants were found on April 12, and
these reach their maximum stage of development about the middle
of May. Tetrasporic plants are most abundant in the latter part
of June and have almost entirely disappeared by the first of August.
Dumontia at South Harpswell must persist through the winter in
the form of sporelings developed from the tetraspores.
The vegetative structure is of a type occurring in many families
of the Florideae. The disk-shaped holdfast is composed of a single
layer of horizontal filaments, each cell of which produces a vertical
ascending branch. Certain of these branches elongate to form the
medullary hyphae of the tubular thallus. Each medullary hypha
has its own initial cell. Every cell of each medullary hypha
produces a radial branch. These radial branches, by repeated
dichotomous forking, form the subcortex and the cortex. Growth
is apical throughout the entire thallus. All the other vegetative
cells, except the trichomes, are uninucleate and contain one chroma-
tophore each. All the chromatin in the resting nucleus is in the
nucleolus. The chromatophore is a clathrate hollow ellipsoid, lying
just inside the cell wall.
The tetraspores are imbedded in the wall of the thallus, and
are distributed evenly throughout practically the entire length
and circumference of the branches and main axis. Younger tetra-
sporangia are found toward the base of the plant. The larger
subcortical cells become modified to form the tetrasporangia. The
chromatophore becomes constricted at intervals, so that it appears
to consist of rows of small irregular plates. These bodies persist
through all stages of the tetrasporangium , and their number is
increased in the tetraspores. No spindle or spireme was seen.
The chromatin in some of the nuclei is in several small bodies,
but these do not resemble chromosomes. The first cleavage
furrow completely divides the tetrasporangium, is perpendicular
1
I
1917] DUNN—DUMONTIA 461
the
The chromatophores in the tetraspores are hollow, oval bodies
with perforated walls. The mature tetraspores do not round off
while imbedded in the thallus. They escape either by the dis-
integration of the cells surrounding them or by a pore formed in
the wall of the thallus.
The spermatia form a continuous layer over nearly the entire
surface of the thallus. The spermatium mother cells terminate
the branches forming* the cortex and subcortex. The chromato-
phore which is present in the young spermatium mother cell
partially or completely disappears as this cell matures. The pro-
toplasm which was in the chromatophore is used in forming the
granular cytoplasm of the mature cell. The youngest spermatium
mother cells observed were binucleate. The first spermatium is
cut off diagonally. The mother cell may again become binucleate
and cut off a second spermatium in a similar manner on the side
opposite to that on which the first was formed. The second
spermatium may be formed while the first one is still attached to
the mother cell. No chromatophore is present in the spermatium.
The nucleus is situated at the distal end of the spermatium in a
dense mass of cytoplasm. The proximal end is vacuolated. The
spermatium is cut off from the mother cell as a cell and not as a
naked protoplast.
The distribution of carpogonial branches in the young female
plants is general, as in the case of the tetrasporangia in the tetra-
sporic plants. The carpogonial branch develops by apical growth
and arises as a lateral outgrowth of a large subcortical cell. A
mature carpogonial branch consists of 6 or 7 cells and a trichogyne
(6 cells always lie in a row). The basal cell ("cell 1 ") sometimes
divides to form a lateral cell. The carpogonium in a mature
branch is always close to or in contact with "cell 2" or "cell 3."
The sporogenous filaments always arise from one of these two cells.
Only a few trichogynes were found projecting beyond the surface
of the thallus. Spermatia were found fused to 4 trichogynes.
Each carpogonial branch which has been fertilized produ
hich
It
are
462 BOTANICAL GAZETTE [june
t
the fusion nucleus in the carpogonium. The sporogenous filaments
grow out toward the auxiliary cell branches. The auxiliary cell
branches in origin, distribution, structure, and mode of develop-
ment are very similar to the carpogonial branches. Only about 1
auxiliary cell branch is initiated to every 7 carpogonial branches.
The time of initiation of the former is a little later than that of the
latter. The mature auxiliary cell branch consists of 4-7 cells.
The second or third cell of the branch is the auxiliary cell, the cell
with which the sporogenous filament fuses and the one which forms
the carpospore. The original nucleus in the auxiliary cell takes no
part in the formation of the carpospores. The nuclei in the car-
pospores are descended from the nucleus which enters the auxiliary
cell from the sporogenous filament.
In the development of the carpospores and cystocarps 3 or
4 gonimoblast filaments arise from the auxiliary cell. Every cell
of these filaments forms a spore. There are about 20 carpospores
in each cystocarp. The pericarp is formed by radial branches
similar to those which form the subcortex and cortex of the wall
of the thallus. Mature carpospores are usually uninucleate, well
filled with a cytoplasm, and contain chromatophores. The chro-
ma tophores are similar to those of the vegetative cells. The nu-
cleus sometimes divides just as the carpospore is about to escape.
Naked carpospores escape through a pore formed in the pericarp.
Carpospores sometime germinate while in the cystocarp. The
ends of branches of mature plants fray, and this disintegration of
cells surrounding the cystocarp furnishes one means of escape for
the carpospores and sporelings.
In the resting nucleus of Dumontia all the chromatin is in the
nucleolus. The nucleolus often contains a vacuole. The chro-
matin in preparation for mitosis passes out of the nucleolus and in
the form of small granules becomes distributed along the linin net.
The net disappears and the granules become massed together to
form larger units, chromosomes. The number of chromosomes was
not definitely determined, but was apparently about 7. No spi-
reme or spindle was seen. After division, the chromatin is again
■
found massed together in the nucleolus.
Johns Hopkins University
•
i
1917] DUNN—DUMONTIA 463
LITERATURE CITED
1. Greville, R. H., Algae Britannicae. Edinburgh. 165. 1830.
2. Harvey, W. H., Phycologia Britannica. London. 1846.
3. Hassencamp, A., Uber die Entwickelung der Cystocarpien bei einigen
Florideen. Bot. Zeit. 60:65-86. 1902.
T 4. Hauptfleisch, P., Die Fruchtentwickelung der Gattungen Chylocladia,
Champia, und Lomentaria. Flora 50:307-367. 1892.
5- Kutzing, F. T\, Phycologia Generalis. Leipzig. 1843.
6. Lewis, I. F., The life history of Griffithsia Bornetiana. Ann. Botany
23:639-690. 1909.
?• , Alternation of generations in certain Florideae. Bot. Gaz.
53:233-246. 191 2.
8* -, The seasonal life-cycle of some red algae at Woods Hole. Plant
World 17:1-35. 1914.
9. Oltmanns, F., Zur Entwickelungsgeschichte der Florideen. Bot. Zeit.
56:99-141. 1898.
J o. -, Morphologie und Biologie der Algen. Jena 1:538-599. 1904.
11. Osterhout, W. J. V., Befruchtung bei Batrachospermum. Flora 87:109-
115. 1900.
12. Schmitz, F., Die Chromatophoren der Algen. Bonn. 1882.
13- -, Untersuchungen iiber die Befruchtung der Florideen. Sitzungsb.
d. Konigl. Akad. Berlin 215-259. 1883.
14. Svedelius, Nils., Uber den Bau und die Entwicklung der Florideen-
Gattung Martensia. Konigl. Svensk. Vet. Akad. Handl. 43: pp. 101.
1908.
*5* -, Uber den Generationswechsel bei Delesseria sanguinea. Svensk.
Bot. Tidsk. 5:260-324. 1911.
16- , Uber die Spermatienbildung bei Delesseria sanguinea. Svensk.
Bot. Tidsk. 6:239-265. 1912.
17. Thuret, G., Etudes phycologiques analyses d'Algues marines. Paris.
1878.
18. Wille, N., Beitrage zur Entwickelungsgeschichte der physiologischen
Gewebesyteme bei einigen Florideen. Nov. Act. Leopold. Carolin.
Akad. Nat. 52:51-100. 1888.
19- Wolfe, J. J., Cytological studies on Nemalion. Ann. Botany 18:608-628.
1904.
20. Yamanouchi, S., The life history of Polysiphonia violacea. Bot. Gaz.
17-401-449. 1906.
carpospores; m
EXPLANATION OF PLATES XIX-XXII
figures.— aux.n., auxiliary cell nucleus; chr., chromatophore ;
; m.h., medullary hyphae; p.g. f protein granule; sbc.c, sub-
ciir^rnnmoronr ^11- c/>6/ QTVirOCfenOUS filament I Sp.U.y
cortical cell; s.c, supernumerary cell; sp.fil., sporogenous filament; sp.n.,
\
464 ' BOTANICAL GAZETTE [june
sporogenous nucleus; sptn.mx., spermatium mother cell; st.c, stalk cell;
trichogy
PLATE XIX
Fig. 8. — Vertical section through holdfast showing horizontal hypha and
vertical ascending, dichotomously branched hyphae; X355.
Fig. 9. — Slightly diagrammatic; vertical section through base of plant
and holdfast ; X 1 70.
Fig. 10.— Longitudinal section through wall of thallus showing radial
hyphae arising as branches of longitudinal, medullary hyphae; X700.
Fig. ii. — Longitudinal section through apex of young branch; X340.
Fig. 12. — Surface view of subcortical cell showing structure of chromato-
phore; Xiooo.
Fig. 13. — Longitudinal section through an intercellular connection show-
ing granules of which disk is composed ; X 700.
Fig. 14. — Longitudinal section through an intercellular connection, between
2 carpospores, in which granules have not yet become grouped together to form
disks; Xiooo.
Fig. 15. — Transverse section through wall of thallus of male plant showing
stalk cells, spermatium mother cells, and spermatia; Xiooo.
Fig. 16. — Longitudinal section through binucleate spermatium mother
cell; X1400.
Fig. 17. — Similar section; spermatium mother cell which has budded off
one spermatium; X 1400.
Fig. 18. — Transverse section through wall of male plant showing free
spermatia imbedded in gelatinous sheath of thallus; Xiooo.
Fig. 19. — Longitudinal section through spermatium mother cell and sper-
matium; chromatophore at base of spermatium mother cell; X1400.
Fig. 20. — Longitudinal section through wall of thallus showing origin of
carpogonial branches; X355.
Figs. 21, 22. — Longitudinal section of first cell of carpogonial branch,
showing mode of origin from subcortical cell; chromatophore is similar to
those of vegetative cells; Xiooo.
Fig. 23. — Longitudinal section of a 2-celled carpogonial branch; Xiooo.
Fig. 24. — Similar section of a 3-celled carpogonial branch; Xiooo.
Fig. 25. — Longitudinal section of a 3-celled carpogonial branch; Xiooo.
Fig. 26. — Similar section of a 4-celled carpogonial branch showing that
number of cells is increased by division of terminal cell; Xiooo.
Fig. 27. — Similar section of a 4-celled carpogonial branch showing that
branches at this stage may be bent to form a right angle; Xiooo.
Fig. 28. — Four-celled carpogonial branch; nucleus in terminal cell contains
7 chromosomes ( ?) ; X 1000.
Fig. 29. — Five-celled carpogonial branch showing position and structure
of chromatophores; Xiooo.
1917] DUNN—DUMONTIA 465
PLATE XX
Fig. 30. — Similar carpogonial branch; terminal cells binucleate; Xiooo.
Fig. 31. — Section of fifth cell of a 6-celled carpogonial branch; 26 chro-
matophores distributed on the cytoplasmic net; X1400.
Fig. 32. — Six-celled mature carpogonial branch showing carpogonium
lying near cell 3; Xiooo.
Fig. 33. — Similar to fig. 32; cell 3 is binucleate; Xiooo.
Fig. 34. — Six-celled carpogonial branch showing coiled trichogyne; X 1000.
Fig. 35. — Seven-celled carpogonial branch showing trichogyne reaching
almost to surf ace of thallus ; Xiooo.
Fig. 36.— Six-celled carpogonial branch showing carpogonium in contact
with cell 3; cell 1 contains 3 nuclei; cytoplasm in cells 4, 5, and 6 is beginning
to disintegrate ; X 1 000.
Fig. 37. — Six-celled carpogonial branch showing much coiled trichogyne
reaching almost to surface of thallus; Xiooo.
Fig. 38. — -Six-celled carpogonial branch showing carpogonium in contact
with cell 3 which is much enlarged, nucleus of which is preparing to divide;
Xiooo.
Figs. 39, 40. — Base of carpogonial branch, and trichogyne projecting
beyond surface of thallus; Xiooo.
Fig. 41. — Base of carpogonial branch (cells 1-4), and trichogyne project-
ing beyond surface of thallus; 8 spermatia attached to trichogyne; Xiooo.
Fig. 42. — Carpogonial branch; 3 sporogenous filaments arising from cell 2;
Xiooo.
Fig. 43. — Carpogonial branch and auxiliary cell branch connected by
sporogenous filaments; auxiliary cell branch consists of 6 cells; X700.
PLATE XXI
Fig. 44.— Auxiliary cell branch; sporogenous filaments lying over cell 4;
Xiooo.
Fig. 45. — Auxiliary cell branch; sporogenous filament fused with cell 3;
Xiooo.
Fig. 46. — Auxiliary cell branch; cells 2 and 3 binucleate and a super-
numerary cell present ; X 1000.
Fig. 47. — Three-celled auxiliary cell branch; Xiooo.
Fig. 48.— Five-celled auxiliary cell branch; nucleus of cell 4 preparing to
divide; cell 1 contains 3 nuclei; Xiooo.
Fig. 49.— Auxiliary cell branch consists of 4 cells; cell 2 binucleate;
Xiooo.
Fig. 50.— Four-celled auxiliary cell branch; cells 1, 3, and 4 binucleate;
Xiooo.
Fig. 5 i .—Four-celled auxiliary cell branch showing dense cytoplasmic
contents of cells; 7 chromosomes and colorless nucleolus in nucleus of cell 3;
Xiooo,
466
BOTANICAL GAZETTE
[JUNE
Fig. 52. — Four-celled auxiliary cell branch; part of chromatin in nuclei of
cells 1 and 3 in granules distributed on linin net; cell 4 contains 2 nuclei;
Xiooo.
Fig. 53. — Four-celled auxiliary cell branch; sporogenous filaments lying
under cell 3 ; X 1000.
Fig. 54. — Sporogenous filament lying near 4-celled auxiliary cell branch;
X550.
Fig. 55. — Auxiliary cell branch showing structure of chromatophores ;
Xiooo.
Fig. 56.— Auxiliary cell branch; 5 carpospores budded off from auxiliary
cell; sporogenous filament fused with auxiliary cell; Xiooo.
Fig. 57. — Auxiliary cell branch; auxiliary nucleus has divided; spo-
rogenous nucleus has just entered auxiliary cell; Xiooo.
Fig. 58. — Section through auxiliary cell branch and 8 young carpospores;
auxiliary nucleus and sporogenous nucleus at opposite ends of auxiliary cells;
Xiooo.
Fig. 59. — Section through auxiliary cell branch and group of young
carpospores; auxiliary cell and one carpospore shaded; sporogenous filament
fused with auxiliary cell; Xiooo.
Fig. 60. — Section through auxiliary cell branch and group of mature
carpospores; auxiliary nucleus and sporogenous nucleus at opposite ends of
auxiliary cell ; X550.
PLATE XXII
Fig. 61. — Same sporogenous filament as in fig. 75 showing cytoplasm
nucleus and chromatophore at tip;
000
Fig. 62. — Section through young cystocarp; 2 of the 18 carpospores which
have arisen from auxiliary cells binucleate;
000
Fig. 63. — Section through young cystocarp showing origin of radial
branches which will form pericarp; X350.
a.
Figs. 64, 65. — Partly shaded; sections of mature
structure of nuclei, distribution of chromatophores, and protein granules;
carpo
Xiooo.
Figs. 66, 67.
carpospores
spores
of
similar
X700.
Fig. 68.— Transverse section of thallus showing 3 normal and 2 abnormal
cystocarps; X350.
Figs. 69, 70, 71. — Sections through carpospores in abnormal cystocarps
showing that nuclear division is not always directly followed by cell division;
700
Fig. 72.
germinating carpospore
Xi7°
Fig, 73. — Chromatophores of germinating carpospores; X14 00
/
BOTANICAL GAZETTE, LX1II
PLATE XIX
DUNN on DUMONTIA
N
/
i
»
1
BOTANICAL GAZETTE, LXIII
PLATE XX
f
DUNN on DUMONTIA
-
*1
A
*
BOTANICAL GAZETTE, LXIII
PLATE XXI
*uvn.
Aux.n
cpa
58
P
57
DUNN on DUMONTIA
I
BOTANICAL GAZETTE, LXIII
PLATE XXII
DUNN on DUMONTIA
4
1917]
DUNN—DUMONTIA
*
467
Fig. 74. — Partly shaded; longitudinal section of germinating carpospore
showing structure and distribution of chromatophores and structure of cyto-
plasm; Xiooo.
Figs. 75, 76. — Sections of germinating carpospores showing sequence of
cell walls during germination; X170.
Fig. 77.— Nucleus of cell 3 of auxiliary cell branch showing chromatin
granules passing from nucleolus to periphery of nucleus; X1400.
Fig. 78. — Nucleus of cell 3 of auxiliary cell branch showing chromatin
granules at periphery of nucleus; X1400.
Fig. 79. — Nucleus of cell 3 of a carpogonial branch; small chromatin
granules present on linin net ; X1400.
Fig. 80. — Nucleus of cell of an auxiliary cell branch; chromatin in small
granules; no nucleolus or linin net present; X1400.
Fig. 81 •—Nucleus of cell 1 of a carpogonial branch showing 7 bodies which
may be chromosomes; X1400.
Fig. 82. — Section of 2 cells of an auxiliary cell branch showing chromatin
granules in nuclei; Xiooo.
PERMEABILITY OF MEMBRANES AS RELATED TO
THEIR COMPOSITION
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 23 1
F. E. Denny
(with six figures)
Introduction
In a previous paper (1) measurements were made of the rate
at which water passes through known areas of certain membranes.
Different species of plants and different membranes of the same
species showed large differences in the rate of penetration. From
these facts the following questions arise. What substances in the
membrane are determining the rate at which water can pass
through it ? Of what relative importance in this process are lipoids,
proteins, tannoids, suberin, pectic substances, etc. ? An attempt
was made to answer these questions by quantitative measurements,
and this paper records the results.
The role of different substances in the membrane in regulating
its permeability to water was determined by comparing the per-
meability of a membrane before and after extracting it with the
solvent of the material studied. Thus, for example, to determine
the effect of lipoid materials upon the permeability of the membrane,
its permeability in the normal condition was first measured; it
was then extracted with a lipoid solvent (for example, acetone), and
its permeability again measured. These two measurements
were then compared. To accompany these measurements, micro-
chemical tests were made to give information as to the nature of
the materials composing the membrane, and the effect of these
extractions upon its composition; and for comparison chemical
analyses were made of the membrane and the extracted materials.
Methods
The osmometer used has been described and figured in a
previous
immersed
stant temperature water bath and the temperature
Botanical Gazette, vol. 63]
[468
1917J DENNY— PERMEABILITY 469
approximately o?i C. In all experiments reported in this paper
the temperature was 25 C. Sodium chloride solutions were
used to induce the osmotic movement of water through the mem-
brane. With the peanut membrane (Arachis hypogaea), which is
rather highly permeable, concentrations of 0.5 M or 0.6 M were
found to be suitable; but for squash, cocklebur, etc., which have
fairly high resistance to water penetration, strong solutions of
sodium chloride were necessary; for use with such membranes a
saturated solution was used, that is, saturated at room temperature.
As noted in the previous paper, different membranes of the
same species differ in their permeability to water. This difficulty
was overcome by using the same membrane under the various
conditions of the experiment. In the tables of results each line of
a table represents data obtained from a single membrane; it is not
possible to compare one membrane with another; the data given
by an individual membrane under different conditions must be
compared.
Effect of extracting membranes with boiling water
It was noted that heating the seed coat of Arachis hypogaea in
boiling water increased the rate at which water passed through.
Measurements were made to determine the extent of this increase;
and other membranes were tested for similar behavior. The
method employed was as follows. A membrane was removed from
a soaked seed, fitted into the osmometer, and a measurement made
of its permeability. It was then removed from the apparatus,
placed in cold distilled water, and heated to boiling point and
allowed to remain in boiling water for 5 minutes. It was then
placed in the osmometer and a reading made of its permeability.
This process was then repeated with other membranes. Table I
shows the results, which are expressed in milligrams of water
passing through a membrane per hour; the same unit is also used
in subsequent tables.
The data show that heating the membrane in boiling water
increased the permeability of the peanut and almond membranes,
but not that of the grapefruit and squash coats. However, the
last two membranes are so slightly permeable that a considerable
470
BOTANICAL GAZETTE
[JUNE
increase in permeability might escape notice. With more delicate
methods an increase under these conditions might appear. In
heating the peanut seed coat a brownish extract was obtained, and
it is thought that the increase was due in a large measure to the
removal of the soluble substances. The nature of these sub-
stances will be treated in that portion of the paper dealing with
microchemical and chemical tests.
TABLE I
Effect of extracting membranes with boiling water
Membrane
Peanut . . .
a
u
u
a
u
a
a
Almond. .
Grapefruit
a
Squash . . .
u
Area in sq.
mm.
I9-635
..
a
50
19
5°
265
635
265
U
19-635
u
a
a
Concen-
tration of
solution
0.5 M
a
O
O
O
O
6M
5M
6M
5M
u
0.5 M
Saturated
a
Rate before
extraction
28.31
32.35
35.05
89-54
54-67
34-67
88.56
40.44
I7-52
o
o
o
Rate after
extraction
66
82
US
212
150
114
210
101
105
o
o
o
II
73
90
59
3 1
00
30
00
10
14
76
Percentage of
increase
135.7
156.3
229.8
137.2
174-4
229.7
I37-I
150.O
500.I
Membrane
Peanut
TABLE II
Effect of heating dry membranes
Area in sq.
mm.
19-635
50.265
Concen-
tration of
solution
Rate before
heating
0.5 M
0.8 M
28.31
78.86
Rate after
heating
42.47
101. 10
Percentage of
increase
50 -03
28.2
To gain further information on this point, the effect of heating
the dry membrane was compared with the effect of heating the
membrane in water. The permeability of a membrane was first
measured; it was air dried, placed in a glass tube, and the latter
heated in water as described. The membrane was then soaked
in water, placed in the osmometer, and a reading again made of its
permeability. Table II expresses these results.
1917]
DENNY— PERM EA BILITY
471
The results indicated in table II show that part of the increase
in permeability after heating in water is due to the heating effect
itself, and that not all the increase is due to the extraction of
materials from the membrane.
Effect of extracting membranes with hot lipoid solvents
The role of lipoid substances present in the membrane in limiting
the rate of penetration of water was investigated by determining
the permeability of a membrane before and after extraction of the
membrane with a lipoid solvent. The solvents used were alcohol,
acetone, and ether. After 4 hours' treatment with the solvent, the
solvent was removed from the membrane and the latter soaked in
water before being placed in the osmometer. Table III shows the
results obtained. In this series all membranes were previously
heated in boiling water. It will be noted that extracting the
Effect of extr.
TABLE III
NG MEMBRANES WITH HOT LIPOID SOLVENTS
Membrane
Peanut
a
u
u
Squash
u
a
Almond
u
Cocklebur,
a
a
Grapefruit
• *
Area in
sq. mm.
50-265
!9-635
50.265
u
«
19-635
50. 265
a
u
50- 265
u
19 635
u
u
u
u
a
Concen-
tration of
solution
Rate
before
extrac-
tion
0.5 M
0.6 M
0.5 M
u
a
Saturated
a
u
a
a
a
a
a
u
a
92.67
5223
98.40
78.86
151-65
101. 10
113.24
11. 12
15 51
11-45
60.66
50-55
20. 22
14-83
22.24
o
o
o
Rate
after ex- Percent-
traction age of
with hot increase
alcohol
Rate
after ex-
Rate
Percent- after ex-
Percent-
14445
9234
228.48;
161 .76'
257.80
117.26
242 . 65
99.42
82.90
III. 22
232.55
279.71
48.28
45.83
56.62
O
IO. II
o
55-9
76.8
132.2
112. 6
69.9
15-9
114 3
793 9
434 5
871.3
283.4
452.3
138.8
209.1
154.6
traction age of traction age of
with hot increase with hot increase
acetone I I ether
171.87
217.70
IOI.IO
98.07
119.08
234.89
279.06
40.44
126.3
169.84
92.47
92.2
809.2
532 6
939 8
287.2
452.o
200.0
279.06
I3I-43
833
77.0
84.1
SO.o
membrane with lipoid solvents greatly increased the permeab
to water,
ment fail
case of the grapefruit seed did such treat-
increase. The different solvents did not
472
BOTANICAL GAZETTE
[JUNE
show large differences, but in general acetone and ether were
more effective than alcohol in increasing the rate, possibly due to
their better dissolving power. The effect of the lipoid solvents
upon the permeability of the squash membrane is to be noted
especially. Most squash membranes will not show any penetra-
tion by water under the conditions of these experiments until they
are treated with a lipoid solvent. They then become rather perme-
able to water.
Effect of extracting membranes with cold lipoid solvent
The significance of lipoids in the membranes is well shown by the
series of measurements made when the extraction was carried on at
room temperature. The unheated membranes were merely placed
in bottles of acetone and allowed to undergo extraction at room
temperature for 18 hours. The permeability of the membranes
was measured before and after such treatment. Table IV shows
the results of this experiment.
TABLE IV
Effect of extracting membranes with cold lipoid solvent
Membrane
Peanut. . .
u
u
Pumpkin. .
u
Squash . . .
u
Almond . . .
a.
Grapefruit
Area in sq
mm.
5 -265
I9-63S
50- 265
u
I9-635
50-26S
19-635
Concen-
tration of
solution
Rate before
extraction
0.5 M
u
u
a
Saturated
u
u
a
«
a
14
65
36
24
O
4
o
49
00
27
04
1752
101 . 10
Rate after ex-
traction with
cold acetone
60.66
246 . 68
88.29
76.84
251.77
141.54
118.64
107.84
34-37
153-67
o
Percentage of
increase
318.6
275.4
145-3
216.6
96.18
53-21
Infiltration experiments
Experiments were made to infiltrate the extracted membrane
with the extracted material. Membranes that had been extracted
were soaked in the solvent containing the lipoid extract and then
exposed to evaporation; by a continuance of this process it was
hoped to impregnate the membrane again with the material that
1917]
DENN Y—PERMEA BILI T Y
473
had previously been
remov
Table V shows these results.
perm
tion, the decrease does not reach the low point exhibited by the
membrane before the original extraction. Apparently the lipoid
materials cannot be put back into the membrane in the condition
and position in which they existed before extraction. This would
indicate an organized distribution of these materials in the mem-
branes in nature.
TABLE V
Effect
OF INFILTl
RATING MEMBRANES
Membrane
Area in sq.
mm.
Concen-
tration of
solution
Rate before
extraction
Rate after
extraction
with hot
acetone
Rate after
extraction
with cold
acetone
Rate after
infiltration
with lipoid
extract
Peanut
SO. 265
'9-63S
a
a
50. 265
U
0.5 M
Saturated
u
u
u
65-71
24.27
4.08
16.17
IOI. 10
121.34
246 . 68
76.84
181.98
30.33
84.92
4246
232.52
258.81
u
Pumpkin
146.26
54-59
298. 26
326.03
Cocklebur
Almond. . .
u
Effect of extracting membranes with calcium chloride
The calcium ion has been shown by Hansteen-Crannter (2)
to reduce the rate of water intake by the cell walls of roots, and it
um
effects upon the permeability of seed coats to water. Membranes
were selected and measurements made of their permeability to water ;
these membranes were then soaked for 24 hours in calcium chloride
solutions of the concentrations described later; the membranes
were then rinsed in distilled water, placed in the osmometer, and
meability
Table VI shows the results.
It thus seems that calcium chloride at the concentrations used
permeability
Whether
similar
et to be determined.
The fact that callose
cium
perm
to the extraction of callose from the membrane. No micro-
chemical differences were noted in membranes before and after
474
BOTANICAL GAZETTE
[JUNE
extraction in calcium chloride, however. The peanut seed coat
became dark brown in color after treatment in saturated calcium
chloride.
TABLE VI
Effect of extracting membranes with calcium chloride
Membrane
Area in sq
mm.
Peanut
English walnut
Almond
Peanut
50.265
19-635
5°. 265
Concen-
tration of
solution
0.5 M
Saturated
u
0.5M
Rate before
Rate after
Percentage
extraction
extraction
of increase
89.17
117.96
323
22.92
38.43
67.6
24. 26
48.53
100.
26.96
3269
21.3
205 • 58
220.06
7.0
Concentra-
tion of CaCl
Saturated
in
1 gm.
259 cc.
water
1 gm. in
259 cc.
water
Microchemical tests
membranes were examined microchemically to determ
the nature of the substances composing them
the
effect upon them of the various methods of treatment. Thin
made
o
tome. These sections were 12.5-25 \i thick. The substances
made
in
fen, together with the tests applied
Tunmann (6) and of Molisch (4)
were consulted for directions regarding these tests.
/<
chromic
concentrated sulphuric acid; soluble in 3 per cent alcoholic potash
after heating; gives the eerie acid reaction; and stains red with
Sudan III.
Tests for tannins. — Blue color with dilute ferric chloride, and
a violet color with o . 1 per cent gold chloride.
Tests for lipoids. — Soluble in acetone, ether, and hot alcohol;
stain red with Sudan III; true fats give crystals when saponified
with potassium hydroxide.
Tests for pectic substances. — Stain red with ruthenium red, and
dissolve by treatment with 2 per cent hydrochloric acid followed
by 2 per cent potassium hydroxide.
1917]
DEX N Y—PERMEA BILI T Y
475
for proteins. — Biuret reaction; those containing tyrosine
Millon
those containing trypto-
phane give a violet color by Liebermann's reaction; other protein
tests were not found to be suitable because the color of the mem-
branes interfered with the tests.
Tests for cellulose. — Blue color with sulphuric acid and iodine,
and dissolves in copper-oxide-ammonia.
..-£
Membrane of peanut (Arachis hypogaea)
The cells in the layer at a (fig. i) have walls of cellulose and
pectin, and their contents consist of granular lipoid substances.
The layer at b contains
coloring matters, of
which tannin was shown
to be one. A water ex-
tract of this seed coat
also gives a positive re-
action for tannin. The
color in this layer is not
completely removed
either by treatment with
hot water or with lipoid
solvents. The layer at
c consists of the old
walls of a parenchyma-
tous tissue that, in the
mature seed coat, is
much compressed.
These walls are of cellu-
lose and pectin. It requires a long period of heating in acid and
dilute base to cause these cells to fall apart. The membrane at d
has no visible contents. The outer walls are of cellulose and
pectin, but of a type very resistant to chromic acid. When sections
of this membrane are treated with chromic acid these walls are the
last to be broken down. Furrows extend across the thick wall of
this layer, but the remains of protoplasmic connections between
the cells could not be detected. Fatty bodies could be seen
.. b
....a
Fig. i. — Cross-section of seed coat of Arachis
hypogaea, X45°-
476
BOTANICAL GAZETTE
[JUNE
occasionally in the layers c and d y but saponification crystals were
not obtained in place in the tissue.
That lipoid substances are present in the peanut membrane
is shown by the analysis of the membrane given later in this paper.
It is probable that the lipoids are present in a very fine state of
dispersion. No distinctly suberized layers could be detected in
the seed coat. All protein tests were likewise negative.
The hot water extraction removes most of the extractable
tannins from the membranes, also part of the lipoid materials;
the increase in permeability by heating the membrane in boiling
water is nrobablv due in larere measure to the removal of these
meability
removal of lipoid ma
terials.
The high permeability of the peanut membrane as com-
pared with other membranes studied is related to its low lipoid
content, and especially to the lack of the layers of cells filled with
lipoid substances that were found in the other seed coats.
Membrane of cocklebur (Xanthium pennsylvanicum)
The walls at a (fig. 2) are thick and lignified; those at b are
much
at c
is a suberized layer containing tannins. Tannins also appear in b,
Fig. 2. — Cross-section of seed coat of Xanthium pennsylvanicum, X45°
but may have diffused there from c . The layer at d and e is an
endosperm layer ; the cell walls marked e are composed of cellulose
and pectin, and the contents d are of lipoid substances. Extrac-
tion with lipoid solvents does not completely remove the fatty
substances from this layer. Protein tests all gave negative results.
Layers a and c are resistant to chromic acid, but layer d, e breaks up,
and the fatty substances flow out in drops.
h
1917] DENNY— PERMEABILITY 477
Membrane of squash {Cucurbita maxima)
This is the greenish membrane surrounding the cotyledons, and
is obtained from soaked seeds by first removing the horny white
spermoderm layer, and then removing the greenish coat from the
cotyledons. At d (fig. 3) is the greenish layer; at is a compressed
>osed of cellulose and pectin. The inner
com
erm
pletely filled with fatty substances. The walls are thin and are
of cellulose and pectin. In
some
tions were positive in layer
d,but most tests were neg-
ative. No tannins were
d
I
mem
branes were absent.
m
Fig. 3. — Cross-section of seed coat of Cucurbita
maxima, X450.
It is believed that the high resistence to the flow of water
through this membrane is due to the high content of lipoid sub-
stances in layer /, m. These substances are almost entirely
removed by treatment with lipoid solvents, and a large increase
in permeability results. It is worthy of note that although this
membrane is highly resistant to the passage of water through it as
compared with other membranes, distinctly suberized layers do
not enter into its composition.
Membrane of almond (Prunus Amygdalus)
Large cells/ (fig. 4) were found to extend from the outer surface
of the seed coat. These were in some places much distorted in
shape and they also did not cover the entire surface. The walls
were of cellulose and pectin, and protein tests gave positive results
.1.1 ... . . . . e 1 > __11 11„
in this layer.
parenchymatous
giving cellulose and pectin reactions. A suberized layer is found
at e and tannin reactions were positive in this region. At m again
is a layer of compressed parenchymatous cell walls. The endo-
sperm layer is at 0, s. The cells are filled with fatty substances (0),
and the cell walls s are composed of cellulose and pectin. These
walls are not thick as compared with either the Citrus or Xanthium
coats. The cell contents also are not completely removed by
extraction with lipoid solvents.
478
[JUNE
BOTANICAL GAZETTE
Membrane of grapefruit {Citrus grandis)
• La> u r { (fi ?,' 5) iS a muciIa S inous mass of cell wall material
giving both cellulose and pectin reactions. The slimy character
of soaked seeds of this species is due to this layer. At o is a thick
/
Fig. 4 .
Cross-section of seed coat of Amygdalus communis, X450
suberized layer impregnated with tannin
materials
and other coloring
membranes
and w.
I he inner wall of this layer is especially well suberized.
esistant to chromic acid than any layer in any other
*~«„^. j.u C tmC K endosperm layer is marked at d
In some places this layer is 2 cells and in other places only
-de the walls are very thick and are composed of cellulose
impregnated with pectin. They break apart on treatment with
I
1917] DENNY— PERMEABILITY 479
dilute acids and bases. The cells themselves are filled with fatty-
substances that are only partly removed by extraction with lipoid
solvents. Even after 18 hours of extraction lipoids may still be
detected in the coat.
In these various experiments the grapefruit seed coat differed
from all others in failing to show increased permeability, or at
least a readable rate of water movement after any of the methods
of extraction. All tests of this membrane with the osmometer
indicated a relatively high resistance of the coat to the passage of
water.
A parallel experiment was carried out to give further evidence
on this point. This was done by comparing the absorption of
.... o
d
w
Fig. 5. — Cross-section of seed coat of Citrus grandis, X45°
water by the seeds, one lot with coats and the other lot without
coats. More than one embryo is usually found in these seeds,
so that when the coat is removed the embryos fall apart and
accurate weighings are impossible. To overcome this difficulty,
a narrow band of seed coat was left around the embryos. This
band held the embryos together so that weighings could be made.
Table VII shows the results obtained, and curves of these results
are shown in fig. 6.
It was found that treating the grapefruit membrane with acids
and bases increased its permeability to such an extent that a read-
able rate of water movement could be obtained. Thus, soaking
a membrane in warm 2 per cent sodium hydroxide increased the
rate from o to 24.26 mg. of water per hour; and in another test
soaking the membrane in 2 per cent sodium hydroxide for 24 hours
increased the rate from o to 72.12 mg. By such treatment, how-
ever, the tissue of the seed undergoes a disintegration, so that the
480
BOTANICAL GAZETTE
[JUNE
outer yellowish layer o (fig. 5) comes off. On using this as a mem-
brane the rate was now found to be 210.27 mg. per hour. This
indicates that the inner portion of the membrane is the one that
TABLE VII
Rate of absorption of water by seeds of Citrus grand is
Time
Coats on
Weight in gm.
Percentage of
water imbibed
Coats off
Weight in gm.
Commencing. .
After 12 hours
u 84 «
" 108 "
144
" 204 "
Oven dry
2.423
2. 762
2.888
2.932
2-942
2.986
3 056
2.283
6
20
26
28
28
30
33
13
9
5
4
9
8
9
2.087
3-135
3-233
3-i7i
3-123
3.129
3-139
1. 971
Percentage of
water imbibed
5
58
64
60
54
58
59
67
9
3
8
8
7
2
HOURS
Fig. 6. — Showing rate of imbibition of water by seed of Citrus grandis; rate with
coats compared with rate without coats; curves obtained by plotting data given in
table VIII.
offers the resistance to the passage of water, and it is believed that
amount
substances surrounded by thick pectinized walls.
Results of chemical analysis
An analysis was made of a quantity of the seed coats of Arachis
hypogaea. A complete analysis for all constituents of the mem-
brane was not attempted, but an examination was made only for
1917] ' DENNY— PERMEABILITY 481
those substances that appeared to be significant as judged by the
experiments
tests.
About 10 pounds of unroasted peanuts were shelled, the pods
discarded, and the seeds put at once into cold water to soften the
seed coats; as soon as the coats were moist enough, they were
removed from the embryos, and dried on blotting paper in the
air. The water in which the seeds had been soaking was brownish
in color; it was made up to a volume of iooocc, with distilled
water; this was called the "preliminary extract/' and later its
content of tannins was determined.
The air dried seed coats were divided into two lots, one lot to
undergo extraction in a manner comparable to the extractions
performed in the experimental work, and the other lot held as a
check to determine the original composition of the membrane before
extraction. The first lot was extracted with water, by putting the
membranes into cold water, raising the temperature of the water
to boiling point, and holding it at this temperature for 5 minutes;
the water was then drained off through a filter, and the residue
washed with cold distilled water until only, a faint straw-colored
liquid passed through the filter. The filtrate was made up to
1500 cc, and was called the "hot water extract." The residue
was vacuum dried, placed in Schleicher and Schull extraction cups,
and extracted in a Soxhlet extractor for 4 hours with acetone.
The extract was made up to a volume of 250 ccm. and was called
the "acetone extract." The insoluble material was called
a
residue."
Methods
timated
thal's method (7, p. 150). The distribution of tannins in the
preliminary extract, in the hot water extract, and in the acetone
extract was determined.
The lipoids in the acetone extract were estimated by removing
a sample, evaporating in a Jena glass dish, and drying to constant
weight in a desiccator. To obtain the amount of lipoid in the hot
water extract a sample was taken; strips of filter paper were dipped
in the samDle until the liouid was absorbed bv the filter paper: the
482
BOTANICAL GAZETTE
[JUNE
latter was then dried in a vacuum desiccator, placed in extraction
shells, and extracted with acetone in a Soxhlet extractor; the
weight of the lipoid material was determined by evaporation.
The nitrogen content was measured by the Kjeldahl method, and
the protein content by the Van Slyke method, both of the latter
methods as described by Mathews (3). An attempt was made
to determine the phosphorus content of the various portions, but it
was found to be very low, and insufficient material was left for
conclusive analyses. The results of the analyses are summarized
in table VIII.
TABLE VIII
Results of analysis of seed coats of Arachis hypogaea; distribution of
MATERIALS
Preliminary
extract
Hot water
extract
(gm.)
Acetone
extract
(gm.)
In residue
(gm.)
Total solids
Lipoids
Nitrogen t
Tannins, equivalent to
cc. KMn0 4
1970.0 cc
3 • 8940
0. 2646
0.0507
1245.0 cc
0.6170
0.6170
0.6784
In sample
(gm.)
0.8816
O.7615
/
* Weight of sample, vacuum dried, 30. 1166 gm.
t Amino acid nitrogen not present in determinable amounts.
*
The following points with reference to table VIII are of interest.
The water extract contains two substances that are believed to be
and lipoids.
permeability of the membrane
Reicharb (5)
importance in the permeability
may
meability of the peanut seed coat to water. Remembering the
effect of the acetone extractions in increasing the permeability
of the membranes, it is interesting to note the low content of lipoid
A small
matter
seems
5
mo\
From
maj
conclude that a part of the increase after
remov
The lack
membrane
1917J DENNY— PERMEABILITY 483
Discussion
These experiments point to the important role of lipoids in
permeability to water. The peanut seed coat, which is the most
permeable of the membranes studied, is the one containing the
least amount of lipoid substances, and when the lipoids are removed
an increase in permeability results. Only in the case of the grape-
fruit did extraction with lipoid solvents fail to increase the per-
meability. Reasons for this behavior are suggested.
Suberized layers have usually been considered the main factors
in restricting water movement through plant membranes. In
these experiments there was no evidence that suberin was a domi-
nant factor. The squash seed coat has no distinctly suberized
layers, and yet it is resistant to the passage of water. These
statements apply only to the membranes studied; in other mem-
branes, more highly impermeable, suberized layers may be of first
importance.
Other substances that appeared to be effective in reducing the
permeability of these seed coats were tannins and pectic sub-
stances, the latter especially when deposited in thick cell walls.
Summary
1. The role of different substances in seed coats in regulating
their permeability to water was studied.
2. Membranes were extracted with water, alcohol, acetone,
ether, and calcium chloride, and their permeability measured before
and after such treatments.
3. Cross-sections of the seed coats were made and tested micro-
chemically to determine the nature of the substances present, and
the effect upon them of the different methods of treatment em-
ployed in the experiment. A chemical analysis of the seed coat
of the peanut and of the extracted materials was made to determine
the content of tannins, lipoids, and proteins.
4. Extraction with hot water increased the permeability of the
peanut and almond seed coats, the percentage increase ranging
from 135 to 500 per cent. Such treatment removed from the
peanut membrane the tannins and a part of the lipoid materials.
484 BOTANICAL GAZETTE [june
5. Extraction with hot water did not measurably increase
the permeability of the grapefruit and squash seed coats; but
these membranes before such treatment were so resistant to the
passage of water that an increase could have resulted from the hot
water extraction without being detected by the apparatus under
the conditions of the experiment.
6. Extraction with hot lipoid solvents increased the per-
meability of all membranes studied except the seed coat of the
*
grapefruit. The percentage of increase ranged from 15 to 871
per cent.
7. Extraction with acetone at room temperature also increased
the permeability of all the seed coats except that of the grape-
fruit. The percentage increase ranged from 53 to 313 per cent.
8. After a membrane had its lipoid content removed, its per-
meability was decreased by impregnating it with the lipoid material
that had been extracted; but in no case was the permeability
reduced to the low point exhibited by it before the process of
extraction.
9. Calcium chloride treatments increased the permeability of
the membranes, but the cause of this increase could not be deter-
mined.
10. The substances found to be factors in determining the
permeability of the membranes to water were lipoids, tannins,
and pec tic substances. Suberized layers were not found to be
significant in the membranes studied, and the presence of soluble
proteins could not be detected.
I wish to express my thanks to Dr. William Crocker and to
Dr. S. H. Eckerson for helpful advice and suggestions during the
progress of this work.
142 South Anderson Street
Los Angeles, Cal.
iqi7] DENNY— PERMEABILITY 485
LITERATURE CITED
Denny, F. E., Permeability of certain plant membranes
Gaz. 63:373-397. figs. 2. 1917.
Hansteen-Cranner, B., tJber das Verhalten des Kultu
Boden Salzen. Jahrb. Wiss. Bot, 53:553-599. 1913-14.
Bot.
3. Mathews
New York. 191 5.
4. Molisch, Hans, Mikrochemie der Pflanze. J
5. Reich ard, Albert, Hat der Gerbstoffe des Ge
Membran? Zeit. Gesamte. Brauw. 33:
145-148, 157-169. 1909.
Tunmann. O.. Pflanzem
Berlin. 1913.
7. U.S. Dept. Agric, Bur. of Chem. Bull. 107 (revised). 1912.
SEXUALITY OF FILAMENT OF SPIROGYRA 1
Bert Cunningham
(with plates xxiii-xxv)
Is the filament of Spirogyra unisexual or bisexual ? This has
*
been a question for many years, but the reports of the great majority
of modern workers would indicate that they regard the filament
as wholly of one sex. The answer to the question hinges upon the
presence of zygotes in both of the conjugating filaments. If they
occur in only one of the two, the filaments may be said to be
unisexual, since one functions as the male and the other functions
as the female; if, on the other hand, they occur in both filaments
and are formed by scalariform conjugation, the filaments may be
said to be bisexual, since the empty cells in each have furnished
the male gametes, while the ones in which the zygotes occur
previously contained female gametes. The latter case is known
as cross-conjugation.
The advocates of the theory of the unisexuality of the filament
urge that as a rule all the male gametes arise in one filament and
pass over into the other, so that zygotes appear in but one of the
two conjugating filaments. They urge also that cases of cross-
conjugation are so rare that they should be considered abnormal-
ities and the result of forced conditions. Strangely enough they
ignore lateral conjugation in so far as the sexuality of the filament
is concerned. On the other hand, those who do not accept this
theory have taken two different positions: one, that the gamete is
absolutely sexless (Hassall 17, p. 130; also Pringsheim, see
Bennett 2) ; and the other, that the filament is bisexual, based
1 This work was done in the Biological Laboratory of Trinity College, Durham,
North Carolina, under the direction of Dr. J. J. Wolfe. The writer wishes at this
point to thank Dr. Wolfe for his many kind and helpful suggestions. He further
desires to acknowledge aid rendered on special questions arising in the course of the
work by Professor G. S. West, of the University of Birmingham, England, and
Professor J. M. Coulter, of the University of Chicago. Thanks are due also to
Mr. J. P. Breedlove, librarian of Trinity College, for his great assistance in securing
literature on the subject.
Botanical Gazette, vol. 63]
[486
IQI7]
CUNNINGHAM— SEXUALITY OF SPIROGYRA
487
principally upon the fact of lateral conjugation. Occasionally a
case of cross-conjugation is presented as evidence, but these cases
have been so isolated that they have been of little value. A clear
case, then, of cross-conjugation occurring normally in a species
would certainly strengthen the position of the advocates of the
bisexuality of the filament.
Vaucher (28), who was apparently the first to work upon
Spirogyra, at least upon the problem of its reproduction, figures it
in most cases in cross-conjugation. Figs. 1-4 of pi. XXIII are photo-
graphic copies from his plates. In his general description of the
Conjuguee he says " ordinarily one of the filaments gives while the
other receives throughout its entire length. Still it is not rare for
the same filament to give in one part of its length and receive in
another in such a manner that some of the cells of the tube are
em
while
or receives throughout its entire length, still it frequently happens,
some
nately." In regard to Conjuguee condensee, he says "the berries
are indifferently lodged in either tube" (Vaucher 28, p. 69)*. . 2
Such statements seem to point clearly to cross-conjugation, but
when we remember that Vaucher, probably because he was
unacquainted with the phenomenon, did not figure or describe
lateral conjugation, and that he was dealing in part with species
illy reproduce in this manner, we have reason to
norm
observing: a combination
scakriform
have been mistaken
for cross-conjugation. Just
the writer.
XXIII
came
under his observation. At first glance the position of
the zygotes in the 2 filaments gives the appearance of cross-
conjugation. Upon closer investigation it is found that the con-
tents of cell (a) probably passed into (b), (c) and (d) represent
another
(/)
regular scalariform manner with (g) and (A) , (i) and (/)
and (k) entirely failed to conjugate.
2 Free translations.
488
BOTANICAL GAZETTE
[JUNE
Vaucher has figured 6 species of Spirogyra, 2 of which are shown
in scalariform conjugation and 4 in cross-conjugation. I have
arranged these species in table I so that the methods of reproduction
assigned by the different writers may be compared.
TABLE I
Species according
to Vaucher
Method of reproduction
Vaucher
Allongee Scalariform
Wolle
DeToni
Adherente
Majeure. .
Portiquis.
Condensee
Renflee . . .
Scalariform
Cross
Cross
Cross
Cross
Scalariform
Scalariform
Scalariform
Scalariform and aplanospores
Scalariform
Scalariform and lateral
Lateral
Not stated
Not stated
Not stated
Often lateral
Often lateral
At first glance there does not seem to be much uniformity, but
if we assume that where DeToni does not state the particular
method of conjugation that the scalariform method is meant, we
find that Wolle and DeToni agree that 5 of these species have
scalariform conjugation. They also agree in assigning lateral
conjugation to renflee. However, DeToni alone states that con-
densee conjugates laterally, while Wolle alone states that portiquis
forms aplanospores. In these 3 cases, therefore, it would be
possible to have combinations with the appearance of cross-
conjugation. Majeure, however, according to both Wolle and
DeToni, conjugates only in the usual scalariform manner- Figur-
ing this species in cross-conjugation by Vaucher is rather surpris-
ing, as will appear in the discussion which follows.
Since there have been but few cases of cross-conjugation
reported, we have reason to doubt its occurrence in as many species
as figured by Vaucher. Furthermore, no other observer up to
the present time has recorded its occurrence in any of these
species. However, the species discussed in the present paper has
been tentatively identified as S. inflata (Vauch.) Rahb., which
according to Rahbenhorst would include Conjuguee renflee of
Vaucher.
Recognizing, then, the facts that (i) Vaucher was unac-
quainted with lateral conjugation, (2) a combination of lateral
iqi;] CUNNINGHAM— SEXUALITY OF SPIROGYRA • 489
and scalariform conjugation resembles true cross-conjugation in
appearance, (3) he has figured cross-conjugation in 3 species in
which this appearance would naturally occur, due to this combi-
nation, (4) no other observer has reported any of these species in
cross-conjugation, the writer feels that there is good ground to
doubt the observation of true cross-conjugation by Vaucher.
Hassall (17) also has figured cross-conjugation, but does not
describe it for any of the species thus figured, although he does
mention it in the general description of the Zygnemaceae. Figs. 6
and 8 of pi. XXIII are reproductions from his plates showing this
phenomenon. While Hassall figures and describes cross-conjuga-
tion, he nowhere claims to have observed its occurrence. One
of the contemporaries of Hassall, in reviewing his book (Hassall
18), says "it is unfortunate that the author has not pointed out
the cases in which the figures are not the result of his own observa-
tions but copied from published plates/' Certain cases are cited
in which Hassall's plates were taken from published plates, and
these tend to cast some doubt on the source of his plates on cross-
conjugation, although they are not among those cited. The
writer has been seeking the originals of these borrowed plates, but
as yet has not been able to locate them, and is therefore uncertain
as to whether or not they exist. Bennett (2, p. 432), in reviewing
the general field, says in regard to Hassall "it is quite possible
that the statement may be the result of an error of observation;
I have often been deceived in this way." Further, Hassall claims
to have discovered lateral conjugation, and with this as his basis
he lays great stress upon the act of conjugation as being without
sex, explaining the movement of the gamete by the "law of
universal gravitation" (Hassall 17, p. 132). He gives the
following reasons for his belief: (1) both cells are alike; (2) repro-
ductive bodies are surrounded by the heavy wall solely for pro-
tection; (3) spores arise in the same species, both with and without
conjugation; and (4) there is conjugation but "no mixing of the
endochrome." As a conclusion he says "thus, so far as can be
presumed, the information already acquired would be opposed to
the belief in the existence of sex as applied to the cells of Conferoa"*
3 This genus as used by Hassall included Spirogyra.
490 BOTANICAL GAZETTE [june
With this as a basis one is not surprised to find him
conjugation as a character of the genus.
(
may
The writer, however, thus far
mono
Bessey (4) figures a case which he calls cross-conjugation. This
figure is reproduced here (pi. XXIII, fig. 7). It is to be noted that
in his description no mention is made of cross-conjugation, although
it is made later (Bessey 5). If the figure is complete, it is by no
means
cells.
in filament A can be explained
formation
conjugating tube. West (29, fig. 64) shows a case of false cross-
conjugation occurring in this manner. The idea is further sup-
ported by the observation of the writer, and diagrammed on
XXIII
filament
form seems
nant to the spherical. This fact was observed by Bessey, as he
states that the zygote of S. protecta is oval in shape, but those of
S. majuscula are spherical, and that the hybrid between these two
assumes the oval shape characteristic of S. protecta. He does
not apply this, however, to the zygote formed in filament A , which
is spherical. If the cell referred to is in cross with anothei
filament
filament should be shown. The figuring
sufficient
Furthermore
is undoubtedly a forced condition. The strenuous efforts of
5. majuscula to reproduce are shown in another case cited by
Bessey (6), in which this species tries to hybridize with Mesocarpus.
Bennett and Murray (3, p. 266) say "as DeBary (ii) has
pointed out, . + . . one of the two filaments is entirely emptied,
while the other is completely filled with zygospores." To this
they have added a footnote "Hassall, however, figures and asserts
to the contrary."
West (30, p. 125) refers to the footnote of Bennett and
Murray, but maintain- that the phenomenon is rare. He state-
that he has seen but a single case, and that was in S. gracilis
(West 29, p. 47). G. S. West, in a more recent personal com-
1917] CUNNINGHAM— SEXUALITY OF SP1R0GYRA 491
munication
enomenon
more
than half a dozen cases of it. However, he sees
no reason why it should not occur, as it represents much the same
enomenon from
In
must
will
Coulter (10, p. 40) briefly describes cross-conjugation but
does not assign it to any species.
On the other hand, the great majority of botanists doubt the
occurrence of cross-conjugation, and with it the bisexuality of the
Spirogyra filament. Agardh (i), according to Hassall (15),
states that one filament is always giving and the other always
receiving. Wood (32) mentions scalariform and lateral conjuga-
tion, but not cross-conjugation. Cooke (9) has 11 plates of
Spirogy
DeBary (ii)
states that one filament gives and the other receives. Wolle
(31) figures and describes 39 species of Spirogyra, citing Vaucher
and Hassall, but does not mention cross-conjugation. Haber-
landt (14), according to Klebs, holds that the filaments are
distinctly sexual. In order to verify this statement, Klebs (22)
grew Spirogyra on nutrient agar, but found that a filament would
not conjugate with itself, and therefore concluded that it was all
of one sex. This experiment might prove the case for one species,
but it hardly appears just to use it as the basis for a sweeping
statement that bisexuality does not occur in Spirogyra. Mottier
(24) cites this experiment as a basis for belief in the unisexuality
of the filament. DeToni (12) absolutely ignores cross-conjugation,
although he cites the plates of both Vaucher and Hassall in
his descriptions of the species figured in this condition by them.
Lotsy (23) states that there is a distinct difference between the
male and the female filaments. Oltmaxns (25, p. 64) states
specifically that we have to do with male and female filaments.
Hertwig (19) makes a similar statement. Engler and Prantl
(13) speak of the visible difference between the male and female
filaments. Robertson (26), who grew Spirogyra extensively
under abnormal conditions, did not find a case either of cross or
lateral conjugation. Since cross-conjugation did not occur in his
492 BOTANICAL GAZETTE [june
own experiments and is so exceedingly rare in the work of others,
he thinks it must be considered a very unusual abnormality.
York (33), who worked several years on the sexuality of Spirogyra,
seeking methods for determining the sex before conjugation, says
"zygotes were never found in both filaments, but only in the one
containing the greater amount of food. The male and female are
morphologically and physiologically different."
Summarizing, it appears that the evidence for bisexuality is
based (1) upon work done over 100 years ago, when the importance
of cross-conjugation was not realized, and has not been verified
since; (2) upon lateral conjugation, a strong basis ignored by the
unisexualists; (3) upon the chance observations of Cleve, Bessey,
and West. At this point it is interesting to note that Hassall
figures no species in cross-conjugation that was thus figured by
Vaucher; that Bessey's species is not that of either Hassall or
Vaucher; and that the one cited by West is still different. Thus
these would all appear to be abnormalities.
On the other hand, the advocates of unisexuality urge (1) that
Klebs found that a filament would not conjugate with itself, hence
it is of one sex; (2) that the work of Vaucher needs verification;
(3) that the figures of Hassall may have been taken from older
works; (4) that, since the species figured by Vaucher and Hassall
are common, the phenomenon should have been observed by
modern investigators; (5) that specialists have seen but few cases,
not more than a dozen, and these have been called abnormalities
because of their rareness; (6) that experimentalists who have
spent years on the sexuality and abnormal conjugation of Spirogyra
have not observed cross-conjugation. All these things point to
the unisexuality of the filament.
If, how r ever, as stated in the beginning of this paper, a true
case of cross-conjugation of Spirogyra should occur normally to
any extent, it would settle the question, for one species at least.
A species in this condition was found by the author while making a
collection of algae along a stream near Durham, North Carolina, on
April 1, 19 1 5. The water stood in pools on the low ground, and
it was from one of these pools that the collection was made. There
was comparatively little of this species mixed with a larger Spiro-
1917] CUNNINGHAM— SEXUALITY OF SPIROGYRA
493
gyra and some germinating Vaucheria. The phenomenon of cross-
conjugation was not observed until the material had been brought
into the laboratory, and heavy freshets prevented further collection.
However, from this interwoven mass, not larger than a pea, more
than 70 slides have been prepared showing cross-conjugation.
Some of the slides have several distinct pairs of filaments in this
condition. Considerable effort was made to secure long filaments,
but this was unsuccessful on account of the intricate tangling of
the mass. This species was again collected early in April 1916, in
approximately the same locality, showing essentially the same
phenomena as the earlier collection, but, owing probably to defi-
cient rainfall, was not abundant and hence it was not possible to
add any important facts not shown by the material gathered the
year before.
A careful investigation of the material shows that all the known
forms of reproduction in Spirogyra are represented in this species.
While aplanospores occur, they are not found frequently, and they
are hard to identify. The regular zygotes are formed by 3 distinct
methods. The most common is the well known scalariform method,
in which the 2 conjugating filaments have the appearance of a
ladder, and the gametes travel in only one direction, so that one
filament contains all the zygotes. This has been followed for
20 to 25 pairs of conjugating cells. Zygotes are formed also by
lateral conjugation, the contents of one cell passing into the adjoin-
ing cell of the same filament. This is accomplished in this species
by the bulging of the cell wall away from the septum at one side
until there is a small opening left between the 2 cells through which
the contents pass. In general appearance the zygotes are like
those formed by scalariform conjugation. Usually the cells
follow the law laid down by Hassall (16, p. 34) that 2 males
alternate with 2 females. This applies only to those filaments in
which lateral conjugation occurs alone. In this species it is
frequently accompanied by genuflexions. This method (lateral
conjugation) occurs in filaments that are also conjugating in the
usual scalariform manner. Zvgotes are further formed by true
©
in which "there is the format
normal zvsrosDore in
Here,
494 BOTANICAL GAZETTE [june
again, the zygotes have the appearance of those formed by scalari-
form conjugation. This has been followed for 16 pairs of conjugat-
ing cells. In this case they are all in conjugation, and, strangely
enough, there are 8 zygotes in each filament. These filaments are
shown schematically in fig. i of pi. XXV, and in part in fig. i of
pi. XXIV. This is the only pair of filaments with any considerable
number of zygotes thus far found which shows the same number
in each of the conjugating filaments. A glance at the plates will
emphasize the fact that, in general, there is no such regular order.
Whole filaments would probably shed further light upon the occur-
rence. Moreover, filaments are found frequently in which both
true cross-conjugation and lateral conjugation occur.
Much care is needed in the study of cross-conjugation, as there
are many chances for error. As previously stated, there are
combinations of scalariform and lateral conjugation that at first
appear to be cases of true cross-conjugation. The writer has used
the utmost care and has been compelled to discard a number of
slides that at first were thought to show cross-conjugation. Only
such cases as have complied with the following rules have been
regarded as in cross-conjugation: (i) zygotes must occur in
both filaments, the swelling of the egg cell is insufficient evi-
dence; (2) the connecting tube must be visible; (3) the male cell
must be empty; (4) end cells must be discarded unless the pre-
ceding conditions are met, since lateral conjugation may have
occurred.
Slides have been permanently mounted in glycerine and from
these the microphotographs of pi. XXIV were taken. They are
made at 225 diameters. The plate shows the original photographs,
and no "retouching" has been done either on the plates or the prints.
Fig. 1 was made from a plain glycerine mount; while the others
were from slides stained either with iodine or Magdala red in order
that the cell walls might be made a little clearer. Figs. 2 and 6
show several filaments conjugating with each other. In the other
figures only 2 filaments are involved. These are, however, very
clear
cases.
made (pi. XXV). In these
filaments
V
19 1 7] CUNNINGHAM
RA 495
twisting
In each case, however,
he has retained all the cells, whether conjugating or not, from the
conjugatin
When
more filaments
parallel also, and as nearly as possible in their relative position.
method
may grasp more
em
Diagram
matic drawings can be followed more readily than the windings
camera drawing, as may
i
pi. XXIV, with fig. i, pi. XXV. The former is a microphotograph
of a portion of the pair of conjugating filaments schematically
represented in the latter. Furthermore, the diagrammatic method
consumes
exhibited at the meeting of the North
Carolina Academy of Science in May 191 5, where they were
observed by a number of botanists. Other slides were sent to
*
1 flat a
Sp
membrane
the ends. The length of the vegetative cell is about 80 ju. and the
width about 15 /jl. The zygote cell is swollen on both sides. The
zygote length is about 43 11 and the width about 28 /*; zygote
oval, considerably pointed, brown at maturity. In these characters
it follows closely the descriptions for Spirogyra inflata. On the
other hand, it is to be noted that the connecting tubes are always
put out by the male cell and fuse directly with the cell wall of the
female cell. This is true regardless of which filament furnishes the
male gamete, and would indicate that the sex character was .
present even before the conjugation tube was put forth.
This species differs also from S. inflata in the phenomenon of
cross-conjugation, which has not been ascribed to it by any modern
work available to the writer. Lotsy (23, p. 198) states that there
is a difference between the male and female filaments of S. inflata,
which can signify scalariform conjugation only. Wolle (31) asserts
that conjugation may be either lateral or scalariform. DeToxi
(12, p. 766) gives Conjugnee renflee of Vaucher (citing Vaucher,
496 BOTANICAL GAZETTE [june
pi. V, fig. 3) as synonymous with S. inflata, and, although Vaucher
figures it in cross-conjugation (pi. I, fig. 4), DeToni merely states
that conjugation is often lateral. Since S. inflate has been under
observation for so long, and these conditions have not been recog-
nized as characters, it would seem that we must either form a new
species for this plant or include these conditions in the description
of S. inflata. The writer is opposed to the multiplication of species,
but these are such distinct characteristics that plants showing them
should, it would seem, be classed separately. Final decision in this
matter, however, must be reserved until the writer or someone
else has had opportunity for further investigation.
The occurrence of this species presents some new problems in
the general theory of sex as it applies to the filament of Spirogyra.
The work on the cytology of this genus has not been entirely
satisfactory, owing to the difficulty of staining and counting the
chromosomes. Chmielewski (7), in 1890, saw evidences of
reduction but was unable to count the chromosomes (Johnson 20).
In 1899 Klebahx (21) followed the reduction in the desmids, and
1 2 years later Trondle (27) succeeded in counting the chromosomes
in Spirogyra and found that a reduction takes place in the germina-
tion of the zygotes. He further found that 4 nuclei were formed,
3 of which degenerate, while "the fourth remains as the nucleus
of the single embryonic plant." Evidently the sex factors are
separated, and one or the other of them is thrown out in this
reduction, since a filament wholly of one sex results.
In the case of lateral conjugation, however, it w r ould seem that
reduction cannot take place in the zygote, as both sexes are present
in the filament. Moreover, it would seem that reduction takes
place in the divisions just preceding reproduction. This may
have occurred in the last division before conjugation. Let [j L
represent a cell which upon division separates the male and female
factors I a 1 s 1 . These conjugating would give alternate zygotes
and empty cells. In this case conjugation is assumed to take
place between gametes derived from the same mother cell.
If, however, they should so divide throughout the filament that
the male of one mother cell should adjoin the female from another,
we should have the alternation of male and female, so that con-
i9i 7l CUNNINGHAM
RA 497
jugation mig ht take place between daughter cells of different
But if they should so divide that
mother cells s s \ s s
the female of one mother cell adjoins the female of another,
should have this occurrence | a [ 9 | g |T"| , which is very character-
istic of lateral conjugation. Hassall (i6), observing such a
phenomenon, stated that in lateral conjugation there were always
2 empty cells separated by 2
West
73) also figures this condition. Wolle (31) makes a similar
statement which, however, is not borne out by his plates, since in
several cases he has described as lateral conjugation conditions
ording to his own figures are manifestly aplanospore
formations (W
% I).
i33> % 1; Pi- x 34,
This characteristic appearance may be brought about, how-
ever, by another method of division. If the cells adjoining
should so divide that the male and female elements alternate
a filament would be produced which upon
conjugation would contain 2 zygotes alternating with 2 empty
If, however, the division should
so occur that male adjoined male and female adjoined female
lZ lT^T^T ^~l- then a further division would produce a filament
containing 4 consecutive males and 4 consecutive females
•
2 2
Assuming that reduction has been retarded until just previous
to reproduction in lateral conjugation, it would be possible for us
em
of 2 empty cells and 2 zygotes. If these filaments should cross-
conjugate (and there is no reason why they should not), they
mi
XXIV
consecutiv
would be 2. Assuming further that the second division has
in the iorm
* % 1 _^f W *
tion of sex cells, the greatest number of consecutive zygotes
would be 4.
umbers cannot explain the conditions figured on pi. XXV
and
498 BOTANICAL GAZETTE [june
r
/
which the writer has observed but not diagrammed, since cases in
which there are more than 4 consecutive zygotes or empty cells show
that division has occurred once or more after reduction. Here,
then, is a distinct and characteristic difference between lateral
and cross-conjugation. In lateral conjugation there can be no
further cell division after reduction is complete, but in cross-
conjugating filaments there may be. A study of the plates shows
that in the case of fig. 2, pi. XXV, division must have occurred 3
times subsequent to reduction in part of the cells at least, in order
to produce the 1 1 consecutive males there shown.
From the foregoing it would seem that the phenomenon of
cross-conjugation lies between lateral and scalariform and partakes
of some of the characters of each. Like the former, the reduction
does not occur in the zygote, but is retarded, and none of the poten-
tial gametes is lost. Like the latter, division continues after
reduction has taken place. For these reasons it would seem that
the filament of Spirogyra, in this species and in those with lateral
conjugation at least, must be homologized with the sporophyte
of higher plants. With these facts as a basis, the following con-
clusions seem to be justified:
1. Bisexuality of the filament does occur in certain species of
Spirogyra, but not necessarily in all species.
2. Reduction may occur in the zygote, in which case a filament
wholly of one sex arises, or reduction may occur just previous to
reproduction, in which case none of the nuclei degenerates, and
filaments of a bisexual nature are produced, which would conjugate
either laterally or by cross-conjugation.
3. Cell division may take place subsequent to reduction, some
cases showing 3 divisions, and this is an essential difference between
lateral and cross-conjugation, since the latter may continue cell
division after reduction is complete but the former apparently
does not.
4. The filament of Spirogyra, in this species and those with
lateral conjugation, is homologous with the sporophyte of higher
plants.
Trinity College
Durham, N.C.
1917] CUNNINGHAM—SEXUALITY OF SPIROGYRA ■ 499
LITERATURE CITED
J
W
20:430-439- I&&3-
London. 1848.
Tour. Linn. Soc
3. Bennett, A. W., and Murray, G., Cryptogamic botany. London. 1889.
4. Bessey, C. E., Hybridization in Spirogyra. Amer. Nat. 18:67-68. 1884.
5- , Note on cross-conjugation. J
6. . Attemnterl hvhridizatinn hptw*
Amer. Nat. 19:800-801. 1885.
*
7- Chmielewski, V., Bot. Zeit. 48:773. 1890.
8. Cleve, P. T., Monografi ofer de Svenska arterna Forsok till en af algens-
familjen Zygnemaceae. pis. 10.
9. Cooke, M. C, British fresh water algae. London, pis. 180. 1882.
io. Coulter, J. M., Barnes, C, and Cowles, H. C, Textbook of botany.
Vol. I. New York. 1910.
11. DeBary, A., Untersuchungen iiber die FamiUe der Conjugation. Leipzig.
1858.
12. DeToni, J. B., Sylloge Algarum. L Chlorophyceae. 725-777. 1889.
13- Engler, A., and Prantl, K., Nattirliche Pflanzenfamilien. Leipzig. 1895.
14* Haberlandt, G., Quoted by Klebs.
15. Hassall, A. H., Ann. Nat. H
x 6. , Ann. Nat. Hist. 9:34.
*7- , British fresh w r ater algae. London. 1845.
18. -, British fresh water algae; rev. in Ann. Nat. Hist. 16:416-419.
19. Hertwig, O., The cell; c
London and New York. i8(
20. Johnson, D.S., The history
N. S. 39:299. 1914.
Klebahn, H., Bot. Jahrb
10:336.
logy
Science
22. Klebs, G., Die Bedingungen der Fortpflantzung bei einigen Algen und
Pilzen. 1896.
23. Lotsy, J. P., Vortrage iiber botanische Stammensgeschichte. I. Algen und
Pilzen. 1907.
24. Mottier, D. M., Fecundation of plants. Carnegie Publ. no. 15. 1904.
25. Oltmanns, F., Morphologie und Biologie der Algen. Jena. 1904.
26. Robertson, R. A., On abnormal conjugation in Spirogyra. Trans, and
Proc. Bot. Soc. Edinburgh 21:185-191. 1899.
27. Trondle, A., Zeitsch. Bot. 3:593. 19"-
28. Vaucher, J. P. E., Histoire d'Confervee d'eau douce.
29. West, G. S., and West, W., Observations on the Cc
Botany 12:29-57. pis. 2. 1898.
30. West, G. S., The British fresh water algae. Cambridge. 1904.
3i- Wolle, F., Fresh water algae of the United States. 2 Vols. Bethlehem,
Penn. 1887.
Geneva. 1803.
Ann
500 BOTANICAL GAZETTE [june
32. Wood, H. C, Contributions to the history of the fresh water algae of
North America. Smithson. Contrib. 19:53-262. pis. 21. 1874.
33. York, H. H., Sexuality of Spirogyra. Science N.S. 38:368-369. 1913.
EXPLANATION OF PLATES XXHI-XXV
PLATE XXIII
*
Fig. i. — Conjuguee majeure (princeps), in cross-conjugation; copy
Vaucher, pi. IV, fig. 3 ; Spirogyra nitida.
Fig. 2. — Conjuguee portiquis Vaucher, in cross-conjugation; copy
Vaucher, pi. V, fig. 1 ; Spirogyra porticalis (MeulL) Cleve.
Fig. 3. — Conjuguee condensee Vaucher, in cross-conjugation; copy
Vaucher, pi. V, fig. 2; Spirogyra condensata (Vaucher) Kutz.
Fig. 4. — Conjuguee renjlee Vaucher, in cross-conjugation; copy Vaucher,
pi. V, fig. 3; Spirogyra inflata (Vaucher) Rabenh.
Fig. 5. — Spirogyra gracilis in cross-conjugation; copy West (29) pi. V,
fig. 81.
Fig. 6. — Zygnema intermedium Hassall, in cross-conjugation; copy
Hassall (17) pi. 38, fig. 8; Spirogyra Weberi Kutz.
Fig. 7. — Spirogyra protecta and 5. majuscula hybridizing; claimed to be
in cross-conjugation; copy of Bessey (4).
Fig. 8. — Zygnema orbicular e Hassall, figured in cross-conjugation; copy
Hassall (17) pi. 19, figs. 1, 2; Spirogyra maxima (Hass.) Wittr.
Fig. 9. — Schematic drawing of " false cross-conjugation" as observed by
the writer.
PLATE XXIV
Fig. 1. — Microphotograph of material mounted in glycerine and unstained;
X225.
Figs. 2-7. — Microphotographs of material mounted in glycerine, and
stained with iodine and Magdala red; X225.
plate xxv
Figs. 1-19. — Schematic drawings of cases of cross-conjugation observed
by the writer.
BOTANICAL GAZETTE, LXII1
PLATE XXIII
1
Cas«/i?Ji
b
2
3
4
6
8
5
9
CUNNINGHAM on SPIROGYRA
*
BOTANICAL GAZETTE, LXIII
PLATE XXIV
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CUNNINGHAM on SPIROCVRA
BOTANICAL GAZETTE, LXIII
PLATE XXV
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CUNNINGHAM on SPIROGYRA
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f
I
ORANGE RUSTS OF RUBUS
J. C. Arthur
(with one figure)
Much interest has been taken recently in the short cycle rusts,
especially since the startling discovery by Kunkel, 1 4 years ago,
that a rust, indistinguishable from the aecia of Gymnoconia inter-
stitialis, would produce promycelia. The year following, Fromme 2
and the writer demonstrated the telial nature of Aecidium tuber-
culatum Ellis and Kellerm., previously treated as a probable
heteroecious rust. Kunkel's discovery stimulated researches by
Olive and Whetzel 3 upon the short cycle rusts of Porto Rico,
leading to the detection of 5 aecidioid forms previously placed under
the form genus Aecidium, and of one uredinoid form quite unlike
anything heretofore known.
Kunkel
embodied
known, pertaining to the blackberry orange rust and of their
probable bearing upon questions of relationship and evolution. He
has concluded that there are in the United States two independent
but in part similar rusts on Rubus, one a long cycle form, which he
identifies with the Gymnoconia inter stitialis of Europe, and the
other a short cycle form, for w]
nitens, first riven bv Schweinitz
name
Carolina*
No clear morphological characters were found by which to dis-
tinguish the short cycle form from the aecia of the long cycle form,
although in germination the two behave quite unlike. It is assumed
1 Kunkel, L. O., The production of a promycelium by the aecidiospores of Caeoma
nitens. Bull. Torr. Bot. Club 40:361. 1913; see also Amer. Jour. Bot. 1:37. 1914.
2 Fromme, F. D. and Arthur, J. C, A new North American Endophyllum. Bull.
Torr. Bot. Club 42:55. 1915.
3 Olive, E. W. and Whetzel, H. H., Endophyllum-like rusts of Porto Rico. Amer.
Jour. Bot. 4:44. 1917.
4 Kunkel, L. O., Further studies of the orange rusts of Rubus in the United States.
Bull. Torr. Bot. Club 43 1559. 1916.
Soi]
[Botanical Gazette, vol. 63
E
502
BOTANICAL GAZETTE [jtoe
KUNKEL
forms
view
A considerable difference in the distribution of the two forms
is evident from Kunkel's studies, the long cycle form being more
common northward and the short cycle form more common south-
ward.
World. Moreov
1
lm
form
especially blackberries.
forms
matter of convenience should be designated by different names,
whatever views may be held as to their relationship. Since the
annearance of Kunkel's first paper, appeals have been made to
writer a number of times
ral names which have beer
meet
therefore, I have concluded to present the following arrangement
of nomenclature and distribution, based upon such facts and
material as are at hand.
The generic name Gymnoconia was founded by Lagerheim 5 m
1894 to more clearly recognize taxonomically the culture work
performed
mer
caeomoid
of Rubus saxatilis with the puccinioid telia (Puccinia Peckiana
Howe) on the same host. The same connection was made two
years later by Clinton 7 at Urbana, Illinois, using "Rubus villosus"
the native blackberry of the region, being without doubt what is
now called R. nigrobaccus. The genus Gymnoconia, therefore,
form, for which
name
from
Kamchatka in 1820 bv Schlechtendahl. 8 There can
Lagerheim
6 Tranzschel, W., Culturversuche mit Caeoma inter stitiale Schlechtd. (C. nitens
Schw.). Hedwigia 3:257. 1893.
? Clinton, G. P., Relationship of Caeoma nitens and Puccinia Peckiana. Box.
Gaz. 20:116. 1895.
8 Schlechtendahl, D. F. L., Horae Phys. Berol. 96. 1820.
<
I
1917J ARTHUR— RUSTS OF RUBUS 5°3
name
name 101
. become
(H
form
as Aecidium nitens, in a paper on the fungi of North Carolina, the
host being reported as Rubus strigosus, but a recent study of the
type collection shows it to be in all probability R. Enslenii Tratt.
This region is far south of the known range of the long cycle form,
may
form in hand. The specific name
combined
with a distinctive generic name.
Many short cycle genera have now been established. Those
which come nearest to the desired characters for the Rubus rust
are the aecidioid genus Endo phyllum , and the uredinoid genus
Botryorhiza. What is now needed is a caeomoid genus, for which no
exists. If any one feels reluctance in placing the telia of a
name
form in a different genus from
form from which they cannot be distinguished morphologically, let
him reflect that he does not hesitate to call the common salt-
grass rust Uromyces Peckianus Farl., when it has numerous meso-
spores, and Puccinia subnitens Diet., when the mesospores are
few, a closer relationship than in the blackberry rusts. Other such
accepted anomalies, in the application of the genera Uromyces and
Puccinia, could be cited. After all, we are not near enough to a
I nomenclature of the rusts along well considered genetic lines to
from
^^
ambiguous
meet these requirements short cycle forms
from
rust
blackberries and raspberries, I take the opportunity to recogniz.
the distinguished service which Dr. Louis Otto Kunkel has
rendered to uredinology, not alone by the discovery of the true
nature of this rust through the use of free surface germination of the
» Schweinitz, L. D., Schrift. Nat. Gesell. Leipzig i :6 9 . 1822.
*
5©4 BOTANICAL GAZETTE [june
spores, but also by his subsequent studies and their clear and
inspiring presentation.
Kunkelia, gen. no v.
..
Cycle of development includes subcuticular pycnia.and sub-
epidermal telia.
Pycnia conical or columnar, the hymenium applanate; ostiolar
filaments wanting.
Telia caeomoid, erumpent, applanate, more or less indefinite in
outline, without peridium or paraphyses. Teliospores catenulate,
globoid or some elongated, i-celled ; wall colorless or pale, verrucose.
Kunkelia nitens (Schwein.), comb. nov. — Aecidium nitens
Schwein. Schrift. Nat. Gesell. Leipzig 1:69. 1822 (type on Rubus
strigosus," error for R. Enslenii, Salem, N.C.) ; Caeoma luminatum
Link in Willd. Sp. PI. 6 2 :6i. 1825 (founded on A. nitens Schwein.);
Caeoma (Aecidium) luminatum Schwein. Trans. Amer. Phil. Soc.
n. ser. 4:293. 1832 (founded on A. nitens Schwein.).
VIII. Idaei 10 (raspberry)
21. R. occidentalis L. (R. idaeus americanus Torr.), black
raspberry. — Nebraska: Peru, May 24, 1900, John L. Sheldon;
Indiana: Bourbon (cult.), May 22, 1889, J. H. Parks; North
Carolina: Leicester, June 12, 1909, B. B. Biggins (Barth. Fungi
Columb. 2937); New York: Hempstead, Long Island, May 13,
1916, Percy Wilson 237; Sparrow Bush, Orange County, May 29,
1916, Percy Wilson 255; South Dakota: Lake Oakwood, June
1890, Miss Stelter.
XV. Ursini (western dewberry)
71. R. vitifolius Cham, and Schlecht— California: Chico,
Copeland
Glen-
dora, Los Angeles County, April 10, 1909, C. F. Baker 5273; Ore-
gon: La Grand, July 20, 1914, C. C. Cate (cult., loganberry).
74. R. macropetalus Dougl. — British Columbia: Agassiz,
June 1 913, James R. Weir 84.
10 The numbered divisions of the hosts and the numbers before the species are
those employed by Rydberg in his monograph of Rubus in N. Am. Flora 22:428.
1913.
I
'
1917] < ARTHUR— RUSTS OF RUBUS 5°5
XVII. Discolores (sand blackberry)
77. R. cuneifolius Pursh.— North Carolina: Raleigh,
without date, F. L. Stevens 136; Alabama: Auburn, April 26,
I 1914, Fred. A. Wolf; Florida: Lake City, April 13, 1900, H. H.
Hume 16; Lake City, April 29, 1896, P. H. Rolfs 25, same without
date 38.
XVIII. Arguti (high blackberry)
78. R. sativus (Bailey) Brainerd— Indiana: Daleville (cult.),
J
79. R. nigrobaccus Bailey (R. villosus Bigel. not Thunb., Ait.,
or Bailey, collections often labelled R. allegheniensis) . — Mary
J
;, Prince George County, May 24, 1910, E. Bartholomew
ningi Columb. 3238); New York: Arkville, Delaware
May 30, 1915, Percy Wilson 69; Orient, Long Island,
ais. Rov Latham 62s: Walden, Orange County, Tune 20,
1908, M. E. Cummings; Ohio: College Hill near Cincinnati,
May 15, 1899, W. H. Aiken (Sydow, Ured. 1389); Kentucky:
Dayton, June 21, 1910, E. Bartholomew (Barth. Fungi Columb.
3327); Indiana: Madison, May 6, 1910, A. G. Johnson;
May
6, 1910, A. G. Johnson; Wirt,
Illinois: Pine Hills, Union County,
Rab.-Wint. Fund Eur. 32 20a) ; Anna
.), June 13, 1888, F. S. Earle (Seym
Missouri: Columbia, May 1886, Tra
. G. M. Reed 70=;: Cedar Gap, Ozark
Mountains
May 22-June 3, 1911, O. E. Lansing, Jr. 2968; Kansas: Man-
hattan, May 23, 1889, Miss May Varney (Kellerm. and Sw.
Kans. Fungi 31); Louisville, June 191 2, E. Bartholomew (Barth. N.
Am. Ured. 605), May 191 2, E. Bartholomew (Barth. Fungi Columb.
4233); Minnesota: Minneapolis, June 17, 1914, Bartholomew and
Holway (Barth. N. Am. Ured. 11 13, Barth. Fungi Columb. 4629);
Iowa: Charles City, May 30 and June 20, 1882, /. C. Arthur;
Decorah, June 11, 1883, E. W. D. Holway; Decorah, June 2, 1886,
E. W. D. Holwav (Barth. N. Am. Ured. 211); Decorah, June 3,
W. D. Holway; Fayette, May 3, 1008, Guy West
Oregon :
J
1913, F. D. Bailey.
*
506 BOTANICAL GAZETTE [june
XIX. Procumbentes (dewberry)
99. R. aboriginum Rydb — Texas: Houston, March 6, 19 14,
Arthur and Fromme 6108.
102. R. procumbens Muhl. (R. canadensis A. Gray, not L.,
New York: Van Cort-
R. subuniflorus Rydb., R. villosus Ait.).-
landt Park, New York City, April 25, 191 2, F. D. Fromme 29;
White Plains, June 7, 1914, Percy Wilson 2; Williamsbridge, New
York City, June 10, 1914, Percy Wilson 4; Pleasantville, West-
chester County, May 14, 191 5, Percy Wilson 63; Hunter Island,
New York City, May 23, 1915, Percy Wilson; Mamaroneck, West-
chester County, June 6, 1915, Percy Wilson 76; Yonkers, May 27,
1916, Percy Wilson 250; Sparrow Bush, Orange County, May 29,
1916, Percy Wilson 257; Ithaca, May 30, 1906, Reddick and
Frazer; New Jersey: West Englewood, Bergen County, June 19,
1915, Percy Wilson 83; Pennsylvania: Lancaster, May 31, 1910,
E. Bartholomew (Barth. Fungi Columb. 3239); Maryland: High
Washington, May
John
Bridge, June 15, 1910, Bartholomew and Swingle (Barth. Fungi
Columb. 3524) ; District of Columbia: Takoma Park, May 1898,
C. L. Shear 1568; Minnesota: Nichols, Aitkin County, June 1892,
E. P. Sheldon; New Hampshire: Temple, June 20, 1888, A.B. and
A. C. Seymour (Seym, and Earle Econ. Fungi 28); Connecticut:
Central Village, June 20, 1903, John L. Sheldon; New Jersey:
Newfield, June 1874, /. B. Ellis (Thiim. Myc. Univ. 446) ; Newfield,
June 1893, J- B. Ellis (Ellis and Ev. Fungi Columb. w): Dela-
81. R. argutus Link (R. Andrewsianus Blanch.). — New York:
Hunter Island, New York City, June 14, 191 2, F. D. Fromme 12,
June 18, 1916, Percy Wilson 294; White Plains, June 7, 1914, Percy
Wilson; Bedford Park, New York City, June 9, 191 5, Percy Wilson
77; Cold Spring Harbor, Long Island, June 13, 191 5, Percy
Wilson 79.
84. R. frondosus Bigel.— New York: Sparrow Bush, Orange
County, May 31, 1916, Percy Wilson 262.
89. R. canadensis L. not A. Gray. — New York: Arkville,
Delaware County, July 6, 1915, Percy Wilson 95.
i 9 i 7 ] ARTHUR— RUSTS OF RUBUS 5°7
ware: Newark, May 15, 1907, H. S. Jackson 1620; Newark, June 6,
1907, Mel. T. Cook 1661; Indiana: Greencastle, May 1893, L. M.
Underwood (Und. Ind. Flora 19); Lafayette, May 21, 1899, Wm.
Stuart; Brookville, May 8, 1915, C. A. Ludwig (Barth. N. Am.
Ured. 141 1 ; Barth. Fungi Columb. 4926).
103. R. Enslenii Tratt— South Carolina: without locality
or date (Ravenel, Fungi Car. 1:91); Georgia: Darien, without
Am. 276): North Carolina: Salem
D
') Rubus sp. (mostly cultivated blackberry).— Maryland
ille, May 24, 1916, H. S. Coe; Missouri: Columbia, May 7
H. S. Reed: Oklahoma: Stillwater (cult.), May 14, i9 J 5
D
Hispidi (running swamp dewberry)
108. R. hispidus L— New York: Hempstead, Long Island,
May 13, 1916, Percy Wilson 234.
XXI. Triviales (southern dewberry)
109. R. lucidus Rydb. (reported in N. Am. Flora 7:181 under
R. trivialis) .—South Carolina: Aiken, March 15, 1909, Arthur and
Kern; Florida: Lake City, March 30, 1895, and February 17,
1906, P. H. Rolfs; St. Augustine, March 27, 1903, E. W. D. Holway
(Barth. N. Am. Ured. 507).
no. R. trivulis Michx— Florida : Lake City, February
H . Rolfs 23 ; Louisiana : New
Bethel
in.
N.Am
under R. trivialis); Texas: Austin, February 27, 1901, W. H. Long
(Barth. Fungi Columb. 1622), March 14, 1901, W. H. Long (Barth.
N. Am. Ured. 1504), March 16, 1901, W. H. Long; Huntsville,
without date, Carl Hartmann, communicated F. D. Heald.
Distribution : Central Florida to southern Texas northward
Baltimore, Maryland
Mississippi
boundary, and along the Atlantic coast within
^
So8 BOTANICAL GAZETTE [june
ioo miles of the sea as far as New York, then nearer to the sea as
far as the coast of New Hampshire, also along the Pacific coast
within ioo miles of the sea from southern California to southeastern
extension of Alaska, the distance from the sea narrowing northward.
Kunkelia Rosae-gymnocarpae (Dietel), comb. nov. — Caeoma
Rosae-gymnocarpae Dietel, Hedwigia 44:334. 1905; Gymnoconia
Rosae-gymnocarpae Arth. N. Am. Flora 7:181. 1912.
Rosa gymnocarpa Nutt. — California: Santa Cruz, without
date, C. L. Anderson, communicated W. G. Farlow; Modoc and
Lassen Counties, "killing wild rosebushes," without date, com-
municated W. G. Farlow; Jackson, Amador County, without
Amador Countv. March
». Hansen 2087.
Distribution: From
fornia.
Gymnoconia interstitialis (Schlecht.) Lagerh. Tromso Mus.
Aarsh. 16:140. 1894. — Caeoma {Uredo) inter stitiale Schlecht. Horae
Phys. Berol. 96. 1820 (type on Rubus arcticus L., Kamchatka);
Uredo interstitialis Schlecht. Horae Phys. Berol. 96. 1820 (variant
of the preceding name) ; Puccinia Peckiana Howe, Peck, Ann. Rep.
N.Y. State Mus. 23:57. 1872 (type on Rubus occidentalis L., New
Baltimore, New York); Puccinia tripustulata Peck, Ann. Rep.
N.Y. State Mus. 24:91. 1872 (type on Rubus "villosus," Greig,
New York) ; Uredo luminatum Thiim. Bull. Soc. Imp. Nat. Moscou
55:85. 1880 (type on Rubus saxatilis L., Minussinsk, Siberia);
Caeoma nitens Burrill, Bull. 111. Lab. Nat. Hist. 2:220. 1885 (type
on Rubus occidentalis L., et al., McLean County, Illinois); Uredo
{Caeoma) nitens DeToni in Sacc. Syll. Fung. 7:866. 1888 (type on
Rubus saxatilis L., et al., Asiatic Siberia); Puccinia interstitialis
Tranz. Hedwigia 32:259. 1893 (founded on Caeoma inter stitiale
Schlecht. and Puccinia Peckiana Howe, supported by cultures on
Rubus saxatilis, Petrograd, Russia) ; Dicaeoma tripustulata Kuntze,
Rev. Gen. 3 3 :407- 1898 (founded on Puccinia tripustulata Peck);
Gymnoconia Peckiana Trotter, Fl. Ital. Crypt. i I2 .'338. 1910
-
1917] ARTHUR— RUSTS OF RUBUS 509
(founded on Puccinia Peckiana Howe and Caeoma inter stitialis
Schlecht., with Rubus saxatilis cited) Gymnoconia Peckiana Kleb.
Krypt. Fl. Brand. 5(1:665. 1913.
A. Hosts for aecia
IV. Arctici (northern dwarf raspberry)
4. R. stellatus Smith. — Alaska: Unalaschka (Bernhardt
herbarium at Mo. Bot. Garden).
5. R. acaulis Michx. (distributed as R. arcticus). — Yukon:
White Horse Rapids, June 16, 1899, /. B. Tarleton.
VIII. Idaei (raspberry)
21. R. occidentalis L. (R. idaeus americanus Torr.), black
raspberry. — Vermont: Charlotte, June 12, 1880, C. G. Pringle
1 1 28; Burlington, June n, 1891, Collins F1363; Ontario: Lon-
don, May 20, 191 1, /. Dearness 1838 c; Glenora, June 7, 191 2,
/. Dearness (Barth. N. Am. Ured. 1208); Michigan: Ann Arbor,
June 6, 1916, C. A. Ludwig 131; Ohio: Olena, Huron County,
June 2, 1902, 0. E. Jennings (Kellerm. Ohio Fungi 67); Massa-
chusetts: Granville, June 1883, A. B. Seymour; Connecticut:
Central Village, June 28, 1903, John L. Sheldon; New York:
Onondaga Valley, June 1885, L. M. Underwood; Ithaca, June 27,
1907, Whetzel and Barms; West Virginia: Seneca, May 30, 1904,
John L. Sheldon 25; Morgantown (cult.), June 8, 1904, John L.
Sheldon 502.
32. R. strigosus Michx. (R. idaeus aculeatissimus Rob. and
Fern.), red raspberry. — Vermont: Burlington, June 10, 1891,
Collins F1362; Burlington, June 14, 1893, L. R. Jones; Burling-
ton, June 10, 1898, W. A. Orion F1807; New Brunswick: Salis-
bury, July 2, 1905, C. L. Moore 9; New York: Lyndonville, June 1,
1886, C. E. F airman; Massachusetts: Newton, 1880, W. G. Farlow
(Ellis, N. Am. Fungi 277, 278, Roumeguere, Fungi Gall. 874).
XVIII. Arguti (high blackberry)
79. R. nigrobaccus Bailey.— Vermont: Without locality,
180?, A. J. Grout; New York: Alcove, May and June 1892, C. L.
5io BOTANICAL GAZETTE [june
Shear (Shear, N.Y. Fungi 133) ; Taberg, Oneida County, June 1887
L. M. Underwood; Trumansburg (cult.), June 4, 1904, H. H
Whetzel; Maine: Isle au Haut, May 31, 1912, Arthur and Ortot
123;
W. A. Kellerman (Rab.-Wint
Fungi Eur. 3225 b); Columbus, May 5, 1901, W. A. Kellerman
3853 (Kellerm. Ohio Fungi 20); Columbus, June 2, 1901, W. A.
Kellerman 3854 (Kellerm. Ohio Fungi 19); Johnston, June 18,
1910, E. Bartholomew (Barth. Fungi Columb. 3630); Michigan:
Portage Lake, Dexter, June 22, 1913, E. B. Mains 38 . 16; Wiscon-
sin:
locality, 1883, L. H. Pammel; Racine, June :
Madison, May 24, 191 1, E. T. Bartholomew
N. Am. Ured. 1007, Barth. Fungi Columb. 3911); Illinois:
Oregon, June 16, 1885, M. B. Watte; Peoria, June 15, 1894, F. E.
McDonald; Indiana: Greencastle, May 1878, Mel. T. Cook;
June 7, 1894, Miss K. E. Golden; Greencastle,
West Wilson; Lafayette, May 18, 1896, Miss
July
Snyder; Greencastle, May 27, 1897, Mel. T. Cook; Lafayette,
May
May
1909, Miss Evelyn Allison; South Bend, June, 1909, Miss Clara
Cunningham; Lafayette, June 6, 191 1, E. Trager; Lafayette,
June 21, 1912, C. A. Ludwig; Indianapolis, June 4, 191 2, N. K.
Thompson; Virginia: Rosalyn, May 28, 1910, C. L. Shear (Barth.
N. Am. Ured. 106).
81. R. argutus Link (R. Andrewsianus Blanch.). — Massa-
chusetts: Barre, June 3, 1899, Harold B. Smith.
91. R. Randii (Bailey) Rydb.— Nova Scotia: Pictou, August 1,
1908, W. P. Eraser (accompanied with telia).
( ?) Rubus sp. (mostly cultivated blackberry). — Ontario: Mus-
koka, June 24, 1890, Macoun; Prince Edward Island: May 7,
1883, Macoun; Vermont: Colchester, June 28, 1894, L. R. Jones;
Maine: Orono, June 1898, P. L. Ricker; New York: Onondaga
Valley, June 1889 (Und. and Cook, Cent. 111. Fungi 51); Penn-
sylvania: Charter Oak, May 1, 19 16; /. C. Arthur; West
Virginia: Morgantown, May 7, 1904, John L. Sheldon 24;
Indiana: Lafayette (cult.), May, 1901, H. B. Dorner; Broad
Ripple (cult.), May 25, 1901, Mrs. L. D. Dickey.
1917] ARTHUR— RUSTS OF RUBUS 511
B. Hosts for telia
V. Saxatiles (dwarf raspberry)
9. R. pubescens Raf. (R. trifiorus Rich., R. canadensis Torr.
not L.). — New Hampshire: Albany, August 1908, W. G. Farlow;
Wisconsin: Oconto County, July 21, 1909, /. /. Davis.
VIII. Idaei (raspberry)
21. R. occidentalis L. (R. idaeus americanus Torr.), black
raspberry. — Vermont: Burlington, August 20, 1890, L. R. Jones
F1299; New York: Ithaca, September 30, 191 2, B. B. Higgins
(Barth. Fungi Columb. 4020); Ithaca, August 28, 1902, H. H.
Whetzel; Poughkeepsie, August 187 1, W. R. Gerard 853; Enfield
near Ithaca, September 15, 1902, /. M. Van Hook; Glen near
Ithaca, August 12, 1904, H. S. Jackson; Junius, September 13,
1904, H. S. Jackson; Massachusetts: Mt. Tom, August 20, 1883,
A. B. Seymour; Newton, W. G. Farlow (Ellis, N. Am. Fungi 261);
Illinois: Urbana, September 7, 1886, M. B. Watte 47.
22. R. strigosus Michx., red raspberry. — New York: Junius,
September 16, 1904, H. S. Jackson.'
Columb
XVIII. Arguti (high blackberry)
79. R. nigrobaccus Bailey (R. villosus Bigel. not Thunb., Ait.,
or Bailey, collections often labelled R. allegheniensis) . — Vermont:
Jamaica, September 12, 1890, A. J. Grout 426; New York:
Alcove, August 1892, C. L. Shear (Shear, N.Y. Fungi 67); Alcove,
August 1893, C. L. Shear (Ellis and Ev. Fungi
Ithaca, September 13, 191 1, B. B. Higgins (Barth. Fungi Columb.
3631); Forest Home near Ithaca (cult.), July 22, 1906, H. II .
Whetzel; Michigan: Leland, August 23, 1913, /. C. Arthur;
Illinois: Urbana, July 29, 1884, T. J. Burrill (Seym, and Earle,
Econ. Fungi 26); without locality, 1887, T. J. Burrill (Ellis and
Ev. Fungi Columb. 653); Middlegrove, September 17, 1007,
E. Bartholomew (Baxth. Fungi Columb. 2568); Indiana: Lafayette,
October 19, 1895, Wm. Stuart; Brookville, September 9, 1916,
C. A. Ludwig 180.
\
512 BOTANICAL GAZETTE [june
89. R. canadensis L. not A. Gray (R. Millspaughi Britton).
Vermont: Stratton, August 7, 1894, A. J. Grout F30 (reported in
N. Am. Flora 7:181 under R. vermontanus) ; New York: sphag-
num swamps at Junius, September 16, 1904, Jackson and Whetzel;
Old Forge, August 25, 1913, L. O. Kunkel; Freeville, September 23,
1902, C. H. Kauffman; Malloryville, August 19, 1904, H. S.
•
Jackson;
Mountains
B. M. Duggar; Maine: Isle au Haut, September 10, 1899, /. C.
Arthur; Michigan: Neebish Isle, August 25, 1899, E. T. and S. A.
Harper; Wisconsin: Price County, September 17 and 22, 191 1,
J. J. Davis; West Virginia: Cheat Bridge, August 18, 1906,
John L. Sheldon 2433.
91. R. Randii (Bailey) Rydb.— Nova Scotia: Pictou, August i,
1908, W. P. Fraser (accompanied with aecia).
Distribution: From a southern boundary beginning in the
vicinity of Boston, Massachusetts, diverging gradually to about 100
miles from the coast as far as central Maryland, then westward to
central Illinois on the Mississippi River, and northward into
Quebec
coast as far
from
Mount
Behring Sea into Asia. In the eastern hemisphere it occurs
of central Europe.
mountains
in the toregoing lists of hosts and localities all the specimens
now in the Arthur Herbarium have been entered. This has been
done for three principal reasons. It will enable any person having
made
both
will
this
moreover
sim
» will lead to many germination tests. Such tests are very
The spores are dusted on the surface of water, and at
of 12-48 hours examined under the microscope to see if
germ tube be long and hyphoid, or short and septate with
formation
m
i9i 7] ARTHUR— RUSTS OF RUBUS 513
5
if drawings are made or the germinating spores preserved dry
between thin sheets of mica, and if a large specimen of the host be
pressed for the purpose of specific determination.
The Rubus hosts of the lists were carefully examined by P. A.
Rydberg of the New York Botanical Garden, on January 30, 191 7,
and the names used are in accordance with his judgment. Of
course, no person can name species of Rubus with much confidence
from leaves alone, as in many collections of the rusts, but the list
presents the nearest approach to accuracy at present possible.
The species have been listed under the divisions of the genus,
and with the serial numbers of the species as given by Rydberg in
his monograph of the genus Rubus in the North American Flora,
better to show the relation of the hosts and their possible suscepti-
I bility to the rusts. Whenever the specimen is said to come from
a cultivated plant, it has been so indicated.
In only one instance have aecia and telia been found on the
same plants. Only from Van Cortlandt Park and a few other
places in the vicinity of New York City, and from Glen, New
Hampshire, have the germination of the spores been satisfactorily
I observed. In all other cases the aecia of the Gymnoconia and the
caeomoid telia of the Kunkelia have been separated largely upon
arbitrary grounds. The geographical factor in connection with
known localities for puccinioid telia has been given much weight,
while various other collateral items of information have been
utilized. In arriving at a conclusion I have had the valuable
assistance of Dr. Kunkel, who kindly went over all the material
with me. One reason for making this assortment in detail is
the hope of enlisting the interest of any botanist who may have the
• opportunity of testing the spore germination in moist air from the
localities and hosts named, thus aiding in gradually verifying
and rectifying the list.
All present evidence goes to show that the long cycle form on
Rubus is essentially a northern species, while the short cycle form
is essentially southern. Fig. i shows the present view regarding
geographical distribution. The chart is based entirely upon the
data given in the preceding lists of hosts, the southern limit of the
Gymnoconia being in large part that indicated by the collections of
Si4
BOTANICAL GAZETTE
Ltune
telia. It will be seen that the two forms overlap along an uncer-
tain line running from eastern Massachusetts not far from the
Atlantic coast to northern Delaware, then through northern Vir-
ginia and West Virginia, south-central Ohio and Indiana to central
Illinois, thence northward along the Mississippi River. On the
Pacific coast the region within ioo miles or less from the sea is
occupied apparently by the short cycle form from Mount St. Elias
<$?> <&*?<■■
\
Fig. i.— Distribution in North America of Gymnoconia inter stitialis (vertical lines)
and Kunkelia nitens (oblique lines).
to southern California, and by the long cycle form from Moun
St. Elias northward and westward into Asia. No collections ar<
known from the arid region of the plains and Rockv Mountains
decision,
most are
forms overlap must
seems
and
southernmost
i Q i 7 ] ARTHUR— RUSTS OF RUBUS 5 J 5
in accord with tendencies recently pointed out by the writer 11 in
America
Not much
So
far as now known, geographical range is more important in
determining the susceptibility of the host than the species of
Rubus. There appears to be
some
form
vated blackberries and raspberries in this country," as suggested
by Kunkel."
Probably no other species known are so well adapted for the
study of the connection between closely related long and short cycle
forms, and their possible evolutionary status.
The rose Caeoma of northern California is transferred to the
genus Kunkelia with some confidence in advance of knowledge
regarding the spore germination, partly because no puccinioid
form has been found associated with it, and partly because of its
general similarity to Kunkelia nitens.
Purdue University
Lafayette, Ind.
"Arthur, J. C, Rusts of the West Indies. Torreya 17:26. 1917.
« Kunkel, L. O., Bull. Torr. Bot. Club 43:569- ioi&.
%\
ARBORES FRUTICESQUE CHINENSES NOVI. II
Camillo Schneider
Clematis chrysocoma Fr., var. sericea, n. comb.— C. montana
var. sericea Fr. apud Finet and Gagnepain in Bull. Soc. Bot. France
50:525. 1903; Contr. Fl. As. Or. 1:10. 1905
W. in Sarg., PI. Wils. iizxa. iot?.
Sp
Yunnan boreali-occidentalis: in sepibus ad viam principalem inter Yung-
pen-ting et lai-nao-ko, alt. arc. 2600 m., 3 Julii
flores magni albi, frutex scandens).
According to the material before me it seems impossible to
separate C. Spoonerii, which is said by the authors to be identical
with C. montana v. sericea Fr., as a distinct species from C. chryso-
coma. I also collected the type on the eastern slopes of the Lichiang
range at about 3600 m., August 1914 (no. 3396). This specimen
agrees well with Franchet's description in Bull. Soc. Bot. France
33:362. 1886. With regard to C. Spoonerii the authors (I.e.) say:
"It appears to us more closely allied to C. chrysocoma Franchet, in
which, however, the flowers are pink and produced on the shoots
of the current season." »—-■■" . — ■ -- . ~
According to Franchet, "dans le C.
extremement
produisent, seulement sous leurs sommet, le bourgeon floral.
11
my specimen (no. 3396) the flowers appear from
the
while in a specimen of a cultivated plant (H
they are produced on this year's shoots. In
by G. Forrest that otherwise agrees well wit]
observe both sorts of flowers. After all. I be
typical C. Sp
• •
specimen collected
forma
may
type of the species. Of C. chrysocoma the flowers are rose pink,
while the color is white in those of var. sericea, but I also collected
a form with pinkish flowers which in its manner of growth is more
var. sericea than typical chrysocoma. To this pinkish flowered
rm belong the two following specimens : Szechuan australis, inter
like
Botanical
[Si6
1 9 1 7 ] SCHNEIDER— NE W CHINESE PL A N TS 517
W
Hoh-si et Te-li-pu, alt. circ. 2000 m., 7 Maji 1914 (no. 1128); and
Yunnan boreali-occidentalis, ad latera orientalia montium niveorum
prope Lichiang, alt. circ. 2800 m., 4 Julii 19 14 (no. 1769).
The only real difference between C. montana sensu lato and
C. chrysocoma sensu lato is furnished by the densely pilose achenes
which are glabrous in C. montana. The yellowish silky pubescence
of C. chrysocoma is not a reliable character, because I collected a
form with almost entirely glabrous leaves but with distinctly pilose
young fruits (in dumetis ad latera orientalia montium niveorum
prope Lichiang fu, alt. circ. 3300m., 19 Julii 1914? no. 1928).
Unfortunately, I do not know the color of the flowers, having seen
only young fruits. The leaves are very much like those of C.
montana var. rubens Wils., and, I presume, this number represents
a new variety of C. chrysocoma.
Clematis Delavayi Fr. var. calvescens, n. var. — A typo
praecipue recedit foliolis subtus tantum laxe strigoso-sericeis viri-
descentibus non argenteo-micantibus margine ex parte distincte
lobulato-dentatis, floribus ut videtur paullo minoribus.
Yunnan boreali-occidentalis: in declivibus montium in valle fluminis
Augusto
typus
typical
while in var. calvescens the under surfaces of the leaves are grayish green.
Mtf
obtusiuscula, n. var. — C. uro-
phylla R. and W. in Sargent, PL Wils. i '.323. 1913, non Franchet.
A typo praecipue recedit foliolis glabrioribus integerrimis vel parce
stamina
non duplo superantibus.
Szechuan orientalis: in monte Omei, alt. 2000 m., 16 Octobns 1003,
typu
prope
00
albi)
900
western Hupeh, that agrees with Franchet's description of C. urophylla in
Bull. Mens. Soc. Linn. Paris 1:433- 1884. The two specimens which have
been referred by Rehder and Wilson to this species look rather different.
The leaves of no. 11347 are entire, while those of no. 31 21 are mostly serrate-
dentate at the margins between the base and the apex. The sepals of the
type are narrow lanceolate, acuminate, and almost twice as long as the stamens.
5 J 8 BOTANICAL GAZETTE
[JUNE
The flowers of var. obtusiuscida are not yet open, but the sepals are distinctly
obtuse and not much longer than the stamens and carpels, which are identical
with those of the type. Both numbers look very much alike. The inflores-
cences are the same as in typical C. urophylla.
v^M> Clematis (Sect. Viorna Prtl., ser. Connatae Koeh.) Kockiana,
n. sp— Frutex scandens habitu C. lasiandrae; ramuli floriferi
striato-sulcati, laxe villosuli. Folia ternata, longiter petiolata;
ovata, basi rotundata vel subcordata, apice subito
acuminata, 5-9.5 cm. longa, 2.5-5 cm. lata petiolulis ad 2 cm.
terminalia
nervisque
minusve stng
costa nervisque lateralibus laxe sericeo-pilosa, venis elevatis con-
spicuis, margine inaequaliter subcrenulato-dentato-serrata, lateralia
minora
Inflo-
rescentia axillaris, pedunculo quam petiolus breviore ad 3 cm.
longo sustenta, paniculata, satis compacta, 3-13-flora et pedunculo
incluso ad 10 cm. longa, sericeo-villosula, bracteis variabilibus
partim foliaceis partim parvis lanceolatis instructa; pedicelli
graciles, ut pedunculus sed densius pilosi, floribus vix vel paullo
longiores; flores nutantes; sepala conniventia, apice revoluta,
ovato-oblonga, 12
sed extus versus basim purpureo-violacea, extus sericeo tomentella,
margine tomentosa, intus glabriuscula ; stamina exteriora sepalis
vix breviora, ad 14 mm. longa, filamentis planis linearibus margine
(et etiam in dorso partim) ima basi excepta dense longeque sericeo-
pilosis quam antherae glabrae circ. 3 ±-plo longioribus, interiora
mm. longa, <-6 mm
filamentis
dito;
in dorso interdum pilis paucis prae-
ium argenteo-plumosum staminibus
subaequilongum desinentia. Achaenia ignota.
Yunnan boreali-occidentalis : in dumetis ad latera orientalia montium
^— _„ r • 1 • «.
A — , w . w ^ b ^uu iu., u oepcemDns 1914, o. ocnneiaer
(no. 3898; typus in Herb. Schneider).
This species has the leaves of C. urophylla Fr. and the inflorescences and
flowers of C. lasiandra Maxim., the sepals of which are much more glabrous.
The plant is named in compliment to Rev. A. Kock of the Pentecostal Mission
at Lichiang-fu, in appreciation of valued service rendered to the author during
the summer of 1914.
i
19 1 7] SCHNEIDER— NEW CHINESE PLANTS 519
■
C ^ Mahonia Alexandri, n. sp. — Arbuscula ad 3 m. alta; ramuli
hornotini flavo-viridi, dense foliati. Folia jugo infimo incluso 12-
15-juga, ad 32 cm. longa, ad 28 cm. lata, rhachi lateraliter sulcata,
jugis inter se 1.5-2 cm. distantibus; foliola lateralia sessilia, anguste
lanceolata, versus apicem et basim folii paullo minora, ceterum
subaequalia, crasse coriacea, laevia, superne dilute viridia, fere
in
nervia
mm
mm
secundariis fere invisibilibus, basi leviter inaequilaterali rotun
subcordata, apice acuminata, spinosa, utrinque satis crasse sin
spinoso-dentata, dentibus distantibus 3-5 divaricatis 1.5-3
longis, basalibus exceptis 4-7 cm. longa, versus basim 1. 2-1.7 cm.,
lata, terminalia simillima, breviter petiolulata; stipulae in basi
dilatata petioli lineari-lanceolatae. Inflorescentiae densiflorae,
fructiferae ad 13 cm. longae; flores ut videtur lutei, ? S
diametientes ; pedicelli 2-4 (-5) mm. longi, bracteis oblongis satis
obtusis aequilongis vel paullo brevioribus suffulti ; sepala 3 externa
minima, late triangularia, 3 media late ovato-oblonga longiora, 3
interna maxima circ. 8 mm. longa, late ovato-elliptica, obtusa;
petala late obovata, circ. 6 mm. longa, apice incisa, basi contracta,
glandulis 2 subparvis instructa; stamina normalia, connectivo satis
obtuso, filamentis edentatis quam antherae fere duplo longioribus;
ovarium ovatum, in stylum attenuatum, ovulis 4-5 sessilibus
instructum. Fructus globosi, valde pruinosi, seminibus maturis
2-3, stylo brevi instructi.
Szechuan australis: inter oppida Yen-yuan Hsien et Yung-ning inter
viculos Wo-lo-ho et Cho-so, ad latera montium, alt. circ. 2600 m., 15 Junii
typus in Herb. Arb. Am
prope
Mengtsze, Lao Kwei-chou (?), 1 Novembris, A. Henry (no. 10309; frutex ad
1 .8 m. altus; in Herb. Hort. Bot. New York).
My specimens with ripe fruits are identical with the flowering ones of
HENRY. It is a distinct species, probably most closely related to M. caesia
Schn. I take much pleasure in naming this species for my friend Mr. Alexan-
mportant
has rendered to the d
absence from Europe.
qjcf* 9 Mahonia caesia, n. sp— Frutex 1-3 m. altus; ramuli (indistincte
reticulata costa subtus elevata) juveniles brunnescentes, leviter
520 BOTANICAL GAZETTE [june
pruinosi. Folia jugo infimo incluso 6-8-juga, jugis i . 5-2 . 5 cm.
inter se distantibus, ad. 25 cm. longa (vel in surculis interdum
fere duplo majora jugis distantioribus) , rhachi tereto plusminusve
glaucescenti ; foliola lateralia sessilia, anguste lanceolata, versus
■
apicem et basim folii paullo minora, ceterum subaequalia, crasse
coriacea, laevia, utrinque in sicco concoloria, flavo-viridia, sed
omnino glaucescentia (plusminusve caesia), basi subtruncato-
obtusa vel latere inferiore rotundata, paullo inaequilateralia,
apice breviter acuminata, spinosa, margine utrinque plusminusve
undulato-sinuato-spinoso-dentata, dentibus 5-9 satis crassis sub-
divaricatis 1.5-2 mm. longis, basalibus valde minoribus ovatis vel \
rectangularibus exceptis 5-9 cm. longa, 1 . 2-2 cm. lata, terminalia
similia; stipulae jugo infimo approximatae, lineares. Inflores-
centiae ignotae.
m. altus).
typu
distinguished
r
Yunnan boreali-occidentalis: ad latera montium inter Lichiang-fu et
tinem Yang-tze ad viam principalem versus Yung-peh-ting, 3 Julii 1914, m
other species that I do not hesitate to describe it as a new species without
having seen flowers or fruits. At first sight the leaves resemble those of M.
Alexandria but they may easily be distinguished from that species by their
different color and nervation, and by the different number of leaflets as well
as by their terete rhachis in which the leaflets are inserted in a different manner.
Mahonia philippinensis, n. sp. — Frutex ad 4-metralis. Folia
7-juga, ad 26 cm. longa et 10 cm. lata, jugo infimo multo minore
basi petioli valde approximato, rhachi satis tenui lateraliter sulcato,
internodiis 2-4 cm. longis; foliola coriacea textura subcrassa,
superne ut videtur satis dilute viridia, paullo nitentia, subtus in
sicco subflavescentia, nervis primariis utrinque distinctis leviter
prominulis, lateralia inferiora superioraque quam media plus-
minusve minora, basalibus minimis ovatis exceptis lanceolata,
basi inaequilaterali cuneata vel obtusata, latere inferiore rotundata
(subcordata), apice acutissima, margine dentibus 3-4 mm. longis
utrinque 4-6 sinuato-dentato-spinosa, minora 3:1 cm. magna,
majora ad 7-7. 5 cm. longa et 2-2. 5 cm. lata, terminalia lanceolata.
basi ovata, ceteris similia, sessilia ? (in specimine unico viso foliolis
3 terminalibus basi plusminusve confluentibus). ad 6: 1 cm. magna.
*
ig 1 7] SCHNEIDER— NEW CHINESE PLANTS 5* 1
cm. lonsae, laxiflorae; earum
triangulares, acuminatae, circ. 1.5 cm. longae; flores lutei?, extus
rubescentes ?, circ. 10 mm. diametientes; pedicelli graciles, 10-12
mm. longi, bracteis ovato-lanceolatis ad 4 mm. longis subacuminatis
suffulti; sepala 3 externa minima, ovata, 3 media majora, late
ovata. z interna maxima, ad 7 mm. longa, late ovata, apice sub-
mm
leviter contracta, glandulis 2 normalibus instructa ; stamina petalis
breviora, apice obtusa, filamentis edentulatis; ovarium ut videtur
in stylum distinctum productum, ovulis 4 sessilibus. Fructus
ignoti.
Insulae Philippinenses : Luzon borealis, Benguet, Baguio, 13 Novembris
1914, R. S. Williams (no. 1460; typus in Herb. Gray; frutex ad 4-metralis,
flores lutei, fructus glauci).
This is a very distinct species, with its loose inflorescences and its long
pedicels. I have not seen the fruits mentioned in the note of the collector.
The texture of the leaves somewhat resembles that of M . napaulensis DC, to
which it seems to be most nearly related.
'^Mahonia nivea, n. sp.— Frutex fide cl. Henry 0.9 m. altus.
Folia 5-6-juga, ad 42 cm. longa et 15 cm. lata, rhachi lateraliter
subsulcato, internodiis 4-5 cm. longis; foliola lateralia sessilia,
late ovata, inferiora superioraque quam media subminora, ceterum
inter se subaequalia, basi paullo inaequilaterali truncato-rotundata ,
apice acuta vel breviter acuminata, tenuiter spinosa, minimis
basalibus exceptis 5-8 cm. longa et 2.5-5 cm. lata, utnnque
distanter breviter indistincte spinoso-serrata, dentibus 4-7_g racl1 "
limis 2 mm. longis porrectis, tenuiter coriacea, superne viridia, laxe
tenuiter reticulata, subtus albida, pruinosa, laxius elavato-reti-
culata, terminalia distincte petiolulata, late ovato-subcordata,
ad 8:5 cm. magna, inrima ovato-orbicularia distanter spmoso-
dentata; stipulae non visae. Flores fructusque ignoti.
Yunnan australis: prope Mengtsze, Pi-che-shen, 21 Novembris, A. Henry
(no. 9863; typus in Herb. Hort. Bot. New York).
According to the note on the label, Henry also collected «fL buds which,
however, are wanting in the specimen before me. Nevertheless, the leaves
of this Mahonia are so distinct that it undoubtedly represents a ^ good new
species. It may easily be distinguished from all the species of the old world by
the snowy white under surface of its finely serrate sessile leaflets.
522 BOTAXICAL GAZETTE [ JUNE
Schisandra grandiflora Hk. f. and Thorns., Fl. Brit. Ind.
1:44. 1872.— King in Ann. R. Bot. Gard. Calcutta 3:219, pi. 6g,
fig. A. 1892; Kadsura grandiflora Wall., Tent. Fl. Nepal. 10, pi. 14.
1824.— The typical S. grandiflora has large white or pinkish white
flowers about 1 in. or more in diameter, and the male flowers have
7-9 sepals. The anthers are elliptic or ovoid-elliptic, with lateral
or subextrorse cells, the filaments of the lower ones being of about
By Finet and Gagnepain and
same
Rehder and Wilson, some forms from
<5
fyS} Schisandra
form a distinct variety that may
grandifl
— S. grandi-
flora Finet and Gagnep. in Bull. Soc. Bot. France 52 : Mem
1905, pro parte; non Hk. f. and Th.; Contr. Fl. As. Or. 2:48. 1907,
pro parte; Rehder and Wilson in Sargent, PI. Wils. 1 : 412. 1913;
S. chinensis Diels in Not. R. Bot. Gard. Edinbgh. 7:398. 1913, non
Baillon — A typo praecipue recedit floribus minoribus vix ultra
2 cm. diametientibus roseis vel sanguineis antheris partim distinctius
extrorsis ovato-ellipticis vel fere ovato-subglobosis apice paullo
apiculatis vel interdum leviter emarginatis loculis subrectis vel
partim satis curvatis.
Yunnan boreali-occidentalis: in vallibus ad latera orientalia montium
Tsang prope Tali-fu, alt. 2800-3200 m., Junio-Augusto 1906, G. Forrest (no.
4797) 5 in dumetis montium niveorum prope Lichiang-fu infra glaciem mag-
3500
fructus maturi
rubri); eodem loco, Octobri 1914, Schneider (no. 3303); in silvis umbrosis ad
angustias montium inter Sung-queh et Teng-chuan,alt. circ. 3200 m., 29 Sept.
1914, C. Schneider (no. 2686); Szechuan australis: in regione Yen Yuan
33°°
17 Maji 1914, C. Schneider (no. 1276; frutex scandens, flores intense rubri); in
silvis supra Hua-li ad flum. Yalung, ad angustias montium boream versus,
alt arc. 3800 m., 28 Maji 1914, C. Schneider (no. 3936; typus in Herb.
Schneider; frutex scandens, flores rubri).
Hupeh
The color of the flowers of the plants collected by myself is almost blood
red, while Forrest says "flowers crimson" and Wilson "flowers flesh pink"
or "deep fleshy pink." They are smaller than those of typical 5. grandiflora,
and the shape of the anthers seems rather variable, the cells being often almost
entirely extrorse and sometimes distinctly curved. In the male flowers I
found mostly 6 sepals, but apparently there are about 9, the outermost being
4
i 9 i 7 ] SCHNEIDER— NEW CHINESE PLANTS 523
rather small and very deciduous. Regarding the fruiting aments and the
| shape, texture, serration, and reticulation of the leaves, it is impossible to
detect sufficient differences between this variety and the type. The under
surface of the mature leaves is often very glaucescent and without a distinct
reticulation, which seems to be much more prominent in the leaves of the type
and also of var. rubriflora. The last one does not, in my opinion, represent a
more distinct form than var. cathayensis.
another variety of S. grandiflora, the i
rubrifl
<
have been somewhat misunderstood by Rehder and Wilson, and I propose
the following combination:
<^\H Schisandra grandiflora, var. rubriflora, n. comb. — 5.
chinensis, var. rubriflora Franchet in Nouv. Arch. Mus. Paris.
8: 192 (PL David. II. 10). 1886; S. grandiflora Fin. and Gagnep. in
Bull. Soc. Bot. France 52 : Mem. IV. 48. i9°5> P ro P arte > non Hk - f -
and Thorn.; Contr. Fl. As. Or. 2:48. 1907, pro parte.— A typo
(
etiam
saepe satis distincte extrorsis.
Szechuan occidentalis: in dumetis montis Xiu-tou, prope Kuan Hsien
^ versus occidentem, alt. 2000-2600 m., 20 Junii 1908, E. H. Wilson
typus in Herb. Am. Arb.).
Wils
enumerata.
[flora are as large as those of typical S. grandifl
but "very dark red" according to Wilson's notes. The number of the sepals
of the male flowers varies from 5 to 7, and I never saw more than 9 in any form of
this species. The shape of the leaves is rather variable, as is also the shape
of the anthers. The true 5. chinensis Baillon is a northern plant, and is readily
5-6
anthers.
diflora always posses
stamens, the filaments of the lower ones becoming almost as long as the anthers.
Arnold Arboretum
Jamaica Plain, Mass
CURRENT LITERATURE
NOTES FOR STUDENTS
Temperature and respiration rate.— Blanc 1 has studied the effect of
changes
germinated
and that of Palladia with etiolated seedlings of the same species. These
two investigators, although working with very similar material, came to very
different conclusions as to the influence of sudden changes of temperature
ADIN
upon the rate of respiration.
temperature or from a high temperature to a medium temperature exciters the
respiration is considered doubtful on account of the fact that, previous to the
change in temperature, the seedlings had been cultivated at different tem-
peratures on sugar solutions.
Blaxc worked with the embryos of Phaseolus vulgaris deprived of their
cotyledons, with the ends of etiolated seedlings of Vicia Faba, and with young
leaves of Secale cereale. The Vicia seedlings had previously been cultivated
on 10 per cent saccharose or 5 per cent glucose solutions. The Phaseolus
embryos and Secale leaves were used both with and without previous culti-
vation on ro per cent saccharose solution. Raising the temperature at which
the experiment was conducted invariably increased the rate of respiration, and
lowering the temperature always decreased the rate. After having undergone
one such change of temperature, samples of the material studied were returned
to the original temperature for a short period (15-30 mins.). It was found
that the rate of respiration during this second period at a given temperature
was higher than that during the first period whenever the temperature had
been raised during the intervening period, and lower whenever the temperature
had been lowered during the intervening period.
In a third series of experiments, embryos of Phaseolus vulgaris and leaves
of Secale cereale were changed from one temperature to a temperature about
20 C. warmer or 20 C. cooler, and the rate of respiration was determined for
3 successive 20-minute periods at the new temperature in comparison with the
experimen
temperature sur la respiration des plantes. Rev. Gen. Bot. 28:65-79. 1916.
'Ziegenbein, E., Untersuchungen iiber den Stoffwechsel und die Athmung
kemiender Kartoffelknollen sowie anderer Pflanzen. Jahrb. Wiss. Bot. 25:595-596.
* Palladin, \V., Influence des changements de temperature sur la respiration
des plantes. Rev. Gen. Bot. 11:241-357, l899 .
524
» ^^amm^
♦
1917] CURRENT LITERATURE 525
rate at the original temperature. It was found that after a change in tem-
perature, the corresponding change in respiratory activity took place only
gradually, apparently not having reached an equilibrium even at the end of
the third 20-minute period. Although the main point is proved, the value of
this part of the work would have been increased by continuing the observations
over a longer time.
Many students will regret that the author did not study oxygen consump-
tion as well as the production of C0 2 , to see whether the respiratory coefficient
was altered by temperature changes. It should be remembered, too, that the
conclusions reached may not hold good for other sorts of material, such as
dormant seeds, the germination of which is greatly stimulated by alternations
of temperature. — G. T. Harrington.
Ecology of bryophytes and lichens. — Ecological studies of liverworts and
c mosses have not been numerous in the past, largely because bryologists have not
been interested in ecology and ecologists have not been sufficiently acquainted
with bryophytes. There are also some difficulties peculiar to the application
of ecological principles to these plants. Some of these have been pointed out
by Watson 4 in attempting, among other things, to define a xerophytic bryo-
phyte. This he decides must be a plant capable of withstanding long periods
of dryness and of having at the end of such periods sufficient living cells to
enable it to resume its growth quickly when water becomes available. He
proceeds to consider the " xerophytic adaptations" under the two principal
heads of structures causing (1) reduction of water output and those resulting
in (2) water storage. The former is accomplished by such means as cushion
forms, investments of dead cells, thick cell walls, leaf arrangement, and capillary
structures; the latter by water sacs, water-storing cells, mucilaginous cells,
and succulent tissue. The writer, however, warns us that many bryophytes
exhibiting " xerophytic adaptations" are not xerophytes.
A second paper by the same author 5 gives in detail the zonation of bryo-
phytes in a wet heath. The shallow water zone is dominated by Aneura
pinguis, P cilia epiphylla, Hypnum scorpioides, and Sphagnum cymbifolium;
the second zone, just above water level, is dominated by Aneura midtifida;
a third zone consists of Sphagnum subnitens, Hypnum intermedium, and asso-
ciated forms, passing imperceptibly into a fourth zone, characterized by Hypnum
cuspidatum, and closely followed by a fifth zone dominated by Brachythecium
pyrum and Cephalozia connivens. This is frequently the end of the series,
although occasionally the drier tussocks show a sixth zone of Hypnum cupressi-
forme var. ericetorum. Drainage and the accumulation of humus are the chief
4 Watson, W., Xerophytic adaptations of bryophytes in relation to habitat.
New Phytol. 13:149-169, 181-190. 1914.
s % A Somerset heath and its bryophytic zonation. New Phytol. 14:80-
93- 1915-
»
526 BOTAXICAL GAZETTE [june
factors in determining the succession. The probable history of the heath is
well discussed and the diagrams are decidedly good and appropriate.
A remarkable instance of the vitality of moss protonema is recorded by
Bristol, 6 who found resting protonemal cells, rich in oil, in dry soil stored in
air-tight bottles for 46-49 years. In cultures these grew and produced pro-
tonema of the ordinary type.
In a series of notes West? has recorded the bryophytes and lichens found
upon trees in parts of Scotland, Wales, and Ireland, and has arranged them
according to abundance. He has found the percentage ratio of some of the
ifc
tar tar ea 2, and Platysma glaucum 1. — Geo. D. Fuller.
fuligi
Variations in wood structure.— Several recent articles have called in ques-
tion some of the "laws of Sanio" for variation in the size of tracheids in
conifers, more particularly that law which states that tracheids increase in
size from the pith radially outward until they reach a definite size, which
remains constant for the following annual rings. Shepard and Bailey 8
found the gradual increase in size up to 30-60 years, but in succeeding years
no constant length was attained. Later the same authors maintained their
points in this journal. 9
Their results were for the greater part confirmed by a detailed study of
Pinus palustris and Pseudotsuga by Miss Gerry, 10 who also finds the longest
tracheids in the early spring wood and the shortest in the late wood. Lee
and Smith 11 now supplement this with an extended study of Pseudotsuga from
British Columbia. Their results, in general, agree with those already cited
except that after a gradual and fairly rapid increase up to the age of 50 years
the tracheid length varies comparatively little, but tends to increase slightly.
They also find an increase in tracheid length up to 42 ft. above the ground,
and then a gradual decrease up to 154 ft., where the measurement ceased. It
is interesting also to note that trees from the coast region appear to have slightly
longer tracheids than those from the mountains.
6 Bristol, B. Muriel, On the remarkable retention of vitality of moss protonema
New Phytol. 15:137-143. 19x6.
7 West, \V., Ecological notes; chiefly cryptogamic. Jour. Linn. Soc. 43o7-85
1915-
\RD
length of conifer fibers. Proc. Soc. Amer. Forest. 9: 1914.
9 Bot. Gaz. 60:66-71. 1915.
10 Gerry, Eloise, A comparison of tracheid dimensions in longleaf pine and
Douglas fir. Science 43:360. 1916.
11 Lee, H. N., and Smith, E. M„, Douglas fir fiber, with special reference to length.
Forest Quart. 14:671-695. 1916.
t
I
«
T
4
1917] CURRENT LITERATURE 527
Extending their work to angiosperms, Tupper and Bailey" found the
average length of their wood elements to be twice that of the corresponding
structures in gymnosperms except in the vesseliess angiosperms, Tetracentron,
Trochodendron, and Drimys, which seem to have the typical gymnospermous
length of wood elements. More recently, Pritchard and Bailey 1 * examined
Carya ovata and reached the general conclusion that both in conifers and in
woody dicotyledons there is a period in the early stages of the life history during
which the woody elements increase in size comparatively rapidly, the length
of the period varying in different groups. Furthermore, different types of
xylem elements, such as tracheids, wood fibers, and vessel segments, behave
very differently, but their size generally fluctuates more or less during the later
stages of the development of the stem. — Geo. D. Fuller.
Taxonomic notes. — Cook 14 has made a comparison of the peculiar branch-
ing and flowering habits of Cacao {Theobroma cacao) and Patachte, formerly
referred to Theobroma, but recently made the basis of a new genus (Tribroma)
by Cook. 15 The comparison deals with morphological and ecological features
of the two genera, as exhibited under cultivation in eastern Guatemala.
Greenman 16 has described a new species of Senecio (5. Hollickii), collected
by Britton and Hollick in Jamaica in 1908.
Grove 17 has described, along with other new fungi, a new genus (Diploo-
spora) of Ascomycetes.
Orton 18 has monographed the North American species of Allodiis, a genus
of Uredinales whose most conspicuous feature is the frequent close association
of aecia and telia on the same plant parts, and the absence of distinct uredinia.
The most interesting fact in connection with its host relationships is that no
host occurs among the Rosales. There are 47 species recognized, including
4 new species and 20 new combinations.
Sprague and Hutchixsox, 19 in connection with a report upon a collection
of African Anonaceae, call attention to the great increase in our knowledge of
12 Tupper, W. W., and Bailey, I. W., The secondary xylems of gymnosperms and
angiosperms. Science 43:323. 1916.
13 Pritchard, R. P., and Bailey, I. W., The significance of certain variations in
anatomical structure of wood. Forest Quart. 14:662-670. 1916.
flowering
Contr.
609-6
15 Jour. Wash. Acad. Sci. 5:288. pis. 46-50, 52, 54. 1915.
Greenm
Ann. Mo. Bot. Gard. 3:201,
202. 1916
** Grove, \Y. B., New or noteworthy fungi. V. Jour. Botany 54:217-223. 1916.
18 Orton, C. R., North American species of Allodus, ^Mem. N.Y. Bot. Gard.
6:173-208. 1916.
x » Sprague, T. A., an
pp. 145-161. figs. j. 19 16.
Kew Bull. no. 6.
5 28 BOTAXICAL GAZETTE [june
the tropical African flora, as illustrated by this family. In 1868, the date of
if tropical Afi
species
and 170 species recorded, and at present 27 genera are known. In the present
limits
ferred. New species are also described in Artabotrys, Isolona, Oxymitra (3),
Uvaria, and Xylopia.
Wernham 20 has published a new genus (Pseudomussaenda) of Rubiaceae
from the " Nile-land districts " of tropical Africa. It includes 3 species formerly
referred to Mussaenda, to which a new species is added.— J. M. C.
Extraction of sap.
Harris
extended the work of Dixon and Atkins on the extraction of sap from plant
tissues. Their primary purpose was to determine something concerning the
nature, amount, and regularity of the change in the concentration of the sap
extracted from a mass of tissue under continuous pressure. The results secured
fully substantiate the conclusions of Ddcon and Atkins that samples of sap
pressed from unfrozen tissues cannot be taken as typical of the original con-
centration of the juices in the tissues. In general, successive samples extracted
by continuous pressing become more concentrated. The authors have shown
that such, however, is not always the case. In some instances the fluid may
become less and less concentrated, for example, extractions from cabbage
leaves. In other instances all fractions may be about the same in concentra-
tion. The development of the freezing method to render tissues permeable
and thereby obtain typical samples of sap has marked a great advance in the
study of the properties of vegetable saps.— Chas. O. Appleman.
A new soil constituent.— An unusual organic soil constituent has been
isolated and identified as a-crotonic acid by Walters and Wise." This
unsaturated acid was found associated with infertility in a Texas soil where
drainage is poor, basic compounds deficient, and oxidizing power low. The
physical and chemical properties of the purified soil acid agree with the proper-
ties of the synthetic acid. The occurrence of this acid in nature had not been
certainly established previously. The authors suggest that it may be formed
from aliphatic /3-hydroxy acids which are produced during the destruction of
cellulose, or by hydrolysis of allyl cyanid which occurs in the essential oils of
some plants.— Charles A. Shull.
20
Werxham, H. F., Pseudomussaenda, a new genus of Rubiaceae. Jour. Botany
54:297-301. 1916.
21
RENCE
extraction of sap from plant tissues by pressure. Biochem. Bull. 5: 130-141. 1916.
■ Walters, E. H., and Wise, Louis E., a-Crotonic acid, a soil constituent.
Jour. Agric. Research 6:1043-1045. 1916.
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.
A
Acacia 244
Acids, excretion by roots 422
Adaptation 146
Aerating system 336
African flora 527
Algae, Puget Sound 415
Allard, H. A., work of 245
Allen, C. E., work of 248
Allodus 527
Amanita 329
Amblynotopsis 329
American forestry 332
Amygdalus communis, membrane of 477
Anatomy of Drimys 335
Appleman, C. O. 528
Arachis hypogaea, membrane of 475
Artemisiastrum 325
Arthonia 244
Arthur, J. C. 501
Ascocarp of Rhizina undulata 282
Ascomycetes, conjugate nuclei in 168
Atmospheric pressure and nectar secre-
tion 257
B
Bacteria, life cycle of 86
Bacteriology, soil 155
Bailey, I. W., work of 526, 527
Bailey, L. H., work of 86
Bakke, A. L. 242; work of 160
Balls, W. L., work of 159
Barium, effect on Spirogyra 406
Bartlett, H. H. 82
Bayliss-EUiott, Jessie S., work of 248
Bean, polycotyledonous 424; quanti-
tative characters in 417
Berry, E. W., work of 167, 168, 243
Betulaceae, anatomy of 247
Blackman, V. H., work of 240
Blake, S. F., work of 244
Blanc, M. L., work of 524
Boerker, R. H., work of 333
Bog theories 424
Bombacites 168
Botrytis cinerea, parasitism of 240
Boysen- Jensen, P., work of 87
Briggs, L. J., work of 160, 327
Bristol, B. Muriel, work of 334, 526
British Columbia forests 331
Britton, N. L., work of 244
Brotherton, W. 417
Brown, W., work of 240
Brown, W. H., work of 419
Bryophyllum calycinum, influence
leaf upon root formation and geotropic
curvature 25
Bryophytes, ecology of 525
Bunzell, H. H. 225
Bursa, monomeric capsules in 246
Burt, E. A., work of 244
of
c
Cabbage yellows 87
Caenomyces 168
Cane sugar and translocation 87
Capitanopsis 329
Capsules, monomeric in Bursa 246
Castalia 86
Cecidiology 156
Cedar swamp on Long Island 335
Cerium, effect on Spirogyra 406
Chamartemisia 325
Chamberlain, C. J. 51, 150
Chien, S. S. 406
China, new plants from 516
Chloachne 167
Chlorenchyma 100
Chodat, R., "La vegetation du Para-
guay" 4U
Christensen, C, work of 244
Cinchona, Botanical Station at 412
Citrus grandis, membrane of 478
Clematis chrysocoma sericea 516; Kock-
iana 518; Delavayi calvescens 517;
urophyila obtusiuscula 517
Cohesion theory 162
Cole, Ruth D. no; work of 335
Collins, F. S., work of 166
Conard, H. S., work of 86
Conductivity water, method for produc-
ing 321
529
53°
INDEX TO VOLUME LXIII
[tune
Conjugate nuclei in Ascomycetes 168
Contributors: Appleman, C. 0. 528;
Arthur, J. C. 501; Bakke, A. L. 242;
Bartlett, H. H. 82; Brotherton, W.
417; Bunzell, H. H. 225; Chamberlain,
C. J. 51, 150; Chien, S. S. 406; Cole,
Ruth D. no; Cook, M. T. 85, 156;
Coulter, J. M. 86, 87, 88, 155, 167,
168, 243, 247, 325, 329, 334, 336, 421,
424, 527; Coulter, M. C. 419; Crocker,
W. 87, 333, 422; Cunningham, B.
486; Denny, F. E. 373, 468; DeVries,
H. 1; Doubt, Sarah L. 209; Dunn,
Grace A. 425; Fitzpatrick, H. M.
282; Forsaith, C. C. 190; Fuller, G. D.
154, 159, 165, 242, 248, 326, 331,
332, 335, 336, 418, 420, 423, 424, 525,
526; Gano, Laura 337; Gardner, N. L.
236; Groves, J. F. 169; Haas, A. R.
232; Harrington, G. T. 524; Harvey,
R. B. 321; Hasselbring, H. 225, 240,
248; Heinefjnann, P. G. 155; Helmick,
B. C. 81, 165; Hill, J. B. 410; Hutchin-
son, A. H. 124; Jeffrey, E. C. 161,
167, 245, 247; Johnson, D. S. 323,
412; Kenoyer, L. A. 249; Kraybill,
H. R. 245; Land, W. J. G. 248; Link,
G. K. K. 88; Loeb, J. 25; Xewman,
H - H. 153, 325; Osterhout, W. J. V.
77, 146, 317; Ramaley, F. 151; Reed,
E. L. 229; Richards, H. M. 83; Rigg,
G. B. 415; Robertson, C. 307; Schneider,
C. 398, 516; Shull, C. A. 83, 162, 330,
528; Shull, G. H. 246; Spessard, E. A.
66; Stevens, F. L. 297; Stober, J. P.
89; Taylor, Aravilla 414; Weniger,
Wanda 266; Wylie, R. B. 135
Cook, M. T. 85, 156
Cook, O. F., work of 527
Cooper, W. S., work of 331, 335, 336
Copnnus 329
Coulter, J. M. 86, 87, 88, 155, 167, 168,
2 43, 247, 325, 329, 334, 336, 421, 424,
S27
Coulter, M. C. 419
Crocker, \V. 87, 333, 422, work of 424
Cucurbita maxima, membrane of 477
Cunningham, B. 486
Cuticle 98
Cycads, fossil 161
Cyperus 244
D
Dahlgren, K. V. O., work of 246
Dalbergites 168
Dalzielia 167
Danthoniopsis 167
Darwin, F., work of 159, 326, 327
Denny, F. E. 373, 468
Desmopsis 166
Deutzia Rehderiana 398
DeVries, H. 1
Dillenites 168
Dioscorea, embryo and seedling of 334
Diploospora 527
Dixon, H. N., work of 244
Doubt, Sarah L. 209
Drimys, anatomy of 335
Ducke, A., work of 421
Duggar, B. M., work of 334
Dumontia filiformis, development of 425
Dunn, Grace A. 425
E
East, E. M., work of 164
Ecology of Northern Florida 337
Embryo, of Dioscorea 334; of Euphorbia
266
Emerson, R. A., work of 417
Enlows, Ella M., work of 85
Entomophilous flow r ers, evolution of 307
Eocene plants 167, 168
Epidermal cells 96; hairs 92; wall 98
Eriolopha 167
Ether and potassium cyanide, effects
of 77 ,
Euphorbia, embryo sac and embryo
of 266
Evolution 153; theory of 325
Excretion of acids by roots 422
■
F
Fairy rings 336
Fernald, M. L., work of 86
Fitzpatrick, H. M. 282
Flax, genetics of 165
Florida, allocthonous peat deposits of
190; ecology of 337
Florissant lake beds, plants of 336
Flowers and insects 307
Forest ecology, history of 333
Forestry 154
Forests, Philippine 418
Forsaith, C. C. 190
Four-lobed mother cells 248
Fred, E. B., "Soil bacteriology" 155
Frost, H. B., work of 82
Fujii, K., work of 164
Fuller, G. D. 154, 159, l6 5, 242, 248,
326, 331, 332, 335, 336, 418, 420, 423,
424, 525, 526; work of 424
G
Gager, C. S., "Fundamentals of bot-
any" 323
Gano, Laura 337
i
1917]
INDEX TO VOLUME LXIII
531
Ganong, W. F., " Textbook of botany"
323 .
Galactia 244
Gall, grape leaf 157; hackberry 158;
peridermium 156
Gardner, N. L. 236
Genetics, of flax 165; of maize endo-
sperm 164
Geotropic curvature in Bryophyllum 25
Gerry, E., work of 526
Gloeocystopsis 330
Gortner, R. A., work of 528
Gossypium, leaf nectaries of 229
Grassland, mountain 242
Greenman, J. M., work of 421, 527
Griffiths, D., work of 422
Grout, A. J., "Moss flora of New York
City" 325
Grove, W. B., work of 248, 527
Groves, J. F. 169; work of 424
Gwynne-Vaughan, D.I, work of 245, 246
Gymnoconia interstitialis 508
H
Haas, A. R. 232; work of 422
Hairs, epidermal 92
Halymenia 166
Harrington, G. T. 524
Harris, J. A., work of 424, 528
Hart, E. B., work of 330
Harvey, R. B. 321
Hasselbring, H. 225, 240, 248
Hawaiian bogs 248
Hawkins, L. A., work of 88
Hayes, H. K., work of 164
Heinemann, P. G. 155
Helmick, B. C. 81; 165
Heptanthus 244
Heribert-Nilsson, N., work of 81
Hill, J. B. 410
Hoar, C. S., work of 247
Howe, M. A., work of 166
Hulth, J. M., "Bref och Skrifvelser af
och till Carl von Linn6" 156
Humidity and nectar secretion 251
Hunter, C, work of 336
Hutchinson, A. H. 124
Hutchinson, J., work of 527
Hydropectis 325
Hypochnus 244
Hyslop, J. A., work of 85
I
Illinois Academy 424
Illuminating gas, response of plants to 209
Inga 422
Insects and plant diseases 85
Isle Royale, flora of 335
Jackson, B. D., "A glossary of botanic
terms" 156
Jeffrey, E. C. 161, 167, 245, 247; work
of 335
Johnson, D. S. 323, 412
Jones, W. N., work of 159
Jost, L., work of 162
K
Kenoyer, L. A. 249
Keteleeria Fortunei, morphology of 124
Kidston, R., work of 245
Kiesselbach, T. A., work of 328
Knightiophyllum 168
Knight, R. C, work of 159
Knowlton, F. H., work of 336
Koidzumi, G., work of 167
Koketsu, R., work of 333
Kraybill, H. R. 245
Kunkelia, Rosae-gymnocarpae
nitens 504
Kuwada, Y., work of 164
508;
L
Laidlaw, C. G. P., work of 159
Lamb, W. H., work of 332
Land, W. J. G. 248
Lange, J. E., work of 329
Lawrence, J. V., work of 528
Leaf size in plant geography 242
Leaves, winter and summer 89
Lee, H. N., work of 526
Lehenbauer, P. A., work of 166
Leonard, M. D., work of 85
Lepiota 329
Liassic flora of Mexico 247
Lichens, ecology of 525; of Bermuda 167
Light and nectar secretion 258
Limonium 86
Link, G. K. K. 88
Linnaeus, correspondence of 156
Livingston, B. E., work of 159, 160, 165,
166, 326
Loeb, J. 25
Lohnis, F., work of 86
Long Island, cedar swamp on 335
Lotsy, J. P., "Evolution by means of
hybridization' ' 153
Lycopodium, in America 66; prothalha
and sporelings of 5 1
M
MacBride, J. F., work of 329
MacCaughey, V., work of 248
Maclnnes, D. A., work of 424
53 2
INDEX TO VOLUME LXIII
[JUNE
519;
sub-
477;
Machaonia 244
Mahonia, Alexandri 519; caesia
nivea 521; Philippine nsis 520
Maidenia 422
Maize endosperm, genetics of 164
Malus, docynioides 400; pumila
sessilis 400
Mathews, D. M., work of 419
Matthiola annua, mutation in 82
Maxonia 244
Megalostylis 329
Mehlhop, Margaret, work of 424
Meliola 330
Membranes, of Amygdalus 477; Arachis
475; Citrus 478; cucurbita
Xanthium 476
Meniphylloides 168
Mexico, Liassic flora of 247
Microtome, freezing device for 236
Mischopleura 167
Moisture and temperature indices 165
Moiisch, H., work of 416
Monomeric capsules in Bursa 246
Moon, F. F., "The book of forestry"
154
Moore, S. L., work of 329
Mosher, Edna, work of 424
Moss, flora 325; from Borneo 244; pro-
tonema, vitality of 334
Mother cells, four-lobed 248
Muenscher, W. L. C, work of 160
Murrill, W. A., work of 156
Mutation in Matthiola annua 82
N
Nectaries, environmental influence on
secretion 249; of Gossypium 229
Neowollastonia 167
Newman, H. H. 153, 325
New Zealand, and subantarctic floras
423; distribution of species in 419
North American flora 155, 325
Nuphar 86
Nymphaea 86
o
Oenothera, blandina and
genetics 81; Lamarckiana
tina 1
Okamura, S., work of 329
Opuntia 422
Orange rusts of Rubus 501
Orton, C. R., work of 527
Osmundaceae, fossil 245
Ostenfeld, C. H., work of 88
Osterhout, W. J. V. 77, 146, 317
Overholts, L. O., work of 330
crosses 9 ;
mut. velu-
P
Palladin, W., work of 524
Pallis, Marietta, work of 420
Pappobolus 167
Paraengelhardtia 168
Paraguay, vegetation of 414
Parasitism, phenomena of 240
Pathology, problems of 297
Pearson, H. H. W., sketch of 150
Peat deposits of Florida 190
Pepoon, H. S., work of 424
Permeability 333; of membranes 468;
of membranes to water 373; tempera-
ture coefficient of 3 1 7
•
potassi
225
Pertz, D. F. M., work of 159
Philippine forests 418
Phytoplankton of the oriental tropics 88
Pilacre and Roesleria 248
Pittier, H., work of 42 2
Plant diseases and insects 85
Platymonas 167
Pollen, imperfection in Rosa no
Polycotyledonous bean 424
Poly gala 244
Polyporaceae 330
Potassium, cyanide and ether, effects of
77; permanganate and peroxidases 225
Potato rot 88
Pritchard, R. P., work of 527
Prothallia, branched 88; of Lycopodium
51, 66
Protoplasm, reaction of 232
Pseudomussaenda 528
Puget Sound algae 415
Q
Quercus 167
R
Rainfall and nectar secretion 253
Ramaley, F., work of 243, 336
Rand, F. V., work of 85
Raunkiaer, C., work of 242
Reed, E. L. 229
Reed, G. B., work of 417
Reed swamp, floating 420
Rendle, A. B., work of 422
Respiration, and temperature rate 5 2 4;
in succulents 83
Reviews: Chodat's "La vegetation du
Paraguay" 414; Fred's "Soil bac-
teriology" 155; Gager's " Fundamentals
of botany" 323; Ganong's "Textbook
of botany" 323; Grout's "Moss flora
of New York City" 325; Hulth's
•^
s
1
1917]
INDEX TO VOLUME LXIII
533
"Bref och Skrifvelser af och till Carl
von Linne" 156; Jackson's "A glossary
of botanic terms" 156; Lotsy's " Evo-
lution by means of hybridization"
153; Moon's "The book of forestry"
154; Rydberg's "North American
flora" 325; Scott's "Theory of evo-
lution" 325
Rhizina undulata, ascocarp of 282
Richards, H. M. 83
Riddle, L. W., work of 167
Rigg, G. B. 415; work of 424
Robertson, C. 307
Rocky Mountains, subalpine plants of
423
Roesleria and Pilacre 248
Roots, excretion of acids 422; formation
in Bryophyllum 25; Texas rot fungus
of 334 .
Rosa, gymnocarpa 508; imperfection of
pollen and mutability no
Rosen, H. R., work of 157
Rubiaceae 422
Rubus, aboriginum 506; acaulis 509;
argutus 506, 510; canadensis 506, 512;
carpinifolius 507; cuneifolius 505;
Enslenii 507; frondosus 506; hispidus
507; lucidus 507; macropetalus 504;
nigrobaccus 505, 509, 511; occidentalis
504, 509, 511; orange rusts of 501;
procumbens 506; pubescens 511; Ran-
dii 510, 512; sativus 505; stellatus
509; strigosus 509, 511; trivialis 507;
vitifolius 504
Rydberg, P. A., "North American flora"
325; work of 423
-
s
Sabatia 86
Safford, W. E., work of 166
Sap, extraction of 528
Schisandra grandiflora 522; cathayensis
522; rubiflora 523
Schneider, C. 398, 516
Scott, W. B., "Theory of evolution
325
Seedling of Dioscorea 334
Seeds, temperature and life duration of
169
Senecio 421, 527
Septobasidium 244
Shantz, H. L., work of 160, 327
Shepard, H. B., work of 526
Shreve, Edith B., work of 326, 327
Shreve, F., work of 332
Shull, C. A. 83, 162, 330, 528
Shull, G. H. 246; work of 246
Skene, ML, work of 423
Skottsberg, C, work of 423
i)
Smith, E. M., work of 526
Smith, G. M., work of 330
Smith, N. R., work of 86
Smith, Pearl M., work of 334
Soil, bacteriology 155; a new constituent
528; moisture index 151
Sorbus, Ambrozyana 401; hupehensis
aperta 403; laxiflora 404; obtusa 403;
tatsienensis 404
Spessard, E. A. 66
Spiraea teretiuscula 399
Spirogyra, effects of barium, strontium,
and cerium on 406; sexuality of fila-
ment 486
Sprague, T. A., work of 527
Staining, manipulating organisms in 410
Standley, P. C., work of 155
Statice 86
Stenophyllus 244
Sterculiocarpus 168
Stevens, F. L. 297; work of 330
Stewart, A., work of 156
Stewart, V. B., work of 85
Stober, J. P. 89
Stomata 94
Strontium, effect on Spirogyra 406
Subalpine plants of Rocky Mountains
423
Subantarctic and New Zealand floras 423
Succulents, respiration in 83
Sulphur nutrition 330
Synaedrys 167
T
Tammes, Tine, work of 165
Taylor, Ara villa 414
Taylor, N., work of 335
Temperature, and moisture indices 165;
and nectar secretion 253; and respira-
tion rate 524
Ternstroemites 168
Theobroma 527
Thuranthos 422
Tobacco, mosaic disease of 245
Tottingham, W. E., work of 330
Translocation and cane sugar 87
Transpiration 159, 326
Trees, large 331
Trelease, S. F., work of 159
Tribroma 527
True, R. H., work of 422
Tunmann, O., work of 416
Tupper, W. W., work of 527
u
Uranthoecium 167
United States, vegetational map of 332
-
■
534
INDEX TO VOLUME LXIII
[JUNE 1917
V
Vallisneria spiralis, pollination of 135
Vegetational map of United States 332
Vesicarpa 325
w
Walters, E. H., work of 528
Watson, W., work of 525
Wells, B. W., work of 158
Welsford, E. J., work of 168; 240
Weniger, Wanda 266
Wernham, H. F., work of 422, 528
West, G. S., work of 167
West, W., work of 526
Wieland, G. R., work of 161, 247
Willis, J. C, work of 420
Wise, L. R., work of 528
Wood structure, variations in 526
Wright, C. H., work of 422
Wuist, Elizabeth D., work of 88
Wylie, R. B., 135
X
Xanthium pennsylvanicum, membrane
of 476
Y
Young, Esther, work of 424
Yuncker, T. G., work of 329
z
Zamia 421
Ziegenbein, E., work of 524