Systematic Anatomy of the Red Algal Genus Rbodopeltist

35 Pages·2008·16.64 MB·English

Systematic Anatomy of the Red Algal Genus Rbodopeltist
YURIKO NOZAWA2
AT PRESENT five species are known in the by Yamada (1931). He compared it with
genus Rbodopeltis, which belongs to the red Harvey's type specimen, determined that it
algal order, Cryptonemiales. Of these, Rbodo belonged to the genus Rbodopeltis, and named
peltis anstralis was first found in Australia, it R. borealis Yamada. Later, from specimens
and the other four species, R. borealis, R. collected at Kotosho, Formosa, and on Chichi
setchelliae, R. liagoroides, and R. gracilis all jima, another was detected which was dissimi
grow in the southern islands of Japan and were lar to R.australis and R. borealis in that it had
described by Yamada. a quiteslender frond and in its structure, which
The firstdescription of a species of the genus was similar to the subgenus Ellgalaxaura of the
Rhodopeltis wasmade byHarvey (1859, 1863), genus Galaxaura. This was named R. gracilis
when he described a red alga, Amphiroa aus Yamada et Tanaka (1935).
tralis Sond., with a tiny red alga, Rhodopeltis After that, from the specimens collected in
australis Harv., parasitic on it. This description Kasyo-to of Formosa, a kind having the outer
was accompanied by a beautifully colored illus most layer of the frond unca1cified was found
tration. In that illustration, on the heart-shaped and, in memory of Mrs. W. A. Setchell, this
segment of Amphiroa australis, an elliptical, was named R. setcbelliae Yamada (1935a). In
dense, scarlet-colored part was delineated as a R. borealis and R.gracilis, the reproductive or
parasitic alga. About this parasitic red alga he gans were too dubious to fix their relationship,
said, "I have puzzled where to place the curi but in this last species the tetrasporangial nerna
ous little parasite here represented. In the struc thecia could be seen clearly, and they were
ture of the skin-like frond there is a near characteristic of the genus Rhodopeltis. From
agreement with Crnoria, so much so that at specimens collected in Nawa and Koshiki-jima
first I referred it to that genus." Amphiroa another new species, R. liagoroides Yamada
australis, which was regarded as a host plant was described (1935a).
by Harvey, had been described by Sonder The above-mentioned four species are those
(1845), and this was followed by Harvey. which were classified Rhodopeltis by Yamada
Kiitzing (1858) treated this asa new genus a long time after the exposition of R. australis
different from Amphiroa. Weber van Bosse (Harv.) Schmitz. For details, reference should
(1904), who agreed with Kiitzing, made a new be made to Yamada's publication (1935b).
genus for it called Litbnrtberon, while Schmitz This paper reminds us of the effort and insight
(1889) published the assertion that Rhodopel needed to get a clear picture of the unca1cified
tis asstralis is not a parasite but only nernathe nemathecia, which when not clear is baffling
cia of Amphiroa anstralis, which was taken for in the determination of species belonging to
a host plant. this genus.
Since 1892, when Schmitz mentioned that the Although Harvey put the genus Rhodopeltis
genus Rhodopeltis contains only one species, into the Squamariaceae, Schmitz put it into
R. australis, no new species was discovered un Rhizophyllidaceae, and Yamada did likewise.
til 1931, when among specimens collected at Kylin (1956) separated Polyides and Rbodo
Ryusensui and Kotosho, Formosa, one quite peltis from the Rhizophyllidaceae and put
similar to R. australis but smaller was found them into a new family, Polyideaceae.
Since the descriptions of the four species by
1Manuscript received August 1967. The delay in Yamada, there has been no exposition of new
publishing this paper is entirely the fault of the
species nor any detailed report about the for
Editors.
mal characteristics of the genus. Reports of
2Professor at Kagoshima Junshin Junior College,
Kagoshirna-shi, Japan. collections, but without descriptions, include
99
100 PACIFIC SCIENCE, Vol. 24, January 1970
Yamada and Tanaka (1938), Tanaka (1950), and considerate guidance and aided by lending
Tanaka (1956), and Segawa and Kamura priceless specimens. Deep and hearty thanks
(1960). According to the investigation made should also be paid to Dr. Takesi Tanaka, Pro
by Tanaka, Rhodopeltis seems to cover a rather fessor at Kagoshima University, for his thor
wide area extending from Formosa, to Ryiikii, ough and comprehensive guidance covering
through the Amami Islands, and to many is many detailed points. Sincere gratitude is due
lands scattered around Kagoshima Prefecture. Dr. Maxwell S. Doty, Professor of Botany,
As described above, both in its generic pecu University of Hawaii, for his kind advice on
liaritiesand in determining the family to which the manuscript and for help in publishing it.
it belongs, the genus Rhodopeltis is of great The author's thanks also go to Dr. Isabella A.
interest. It is especially interesting that this Abbott of Hopkins Marine Station, Stanford
genus is characterized clearly by its distribu University, who read my manuscript very care
tional area being confined, with the exception fully and gave me valuable suggestions.
only of R. australis, to the southwestern islands
of Japan. The characteristics of the genus are
METHODS
further clarified by minute examination of the
process of nemathecia formation and the man In the study of Rhodopeltis, decalcification
ner of development of the reproductive organs. is necessary. In this processcare must be taken
The results thus obtained are expected to offer not to injure the uncalcified nemathecia. The
a clue to determining its position in the classi most common method of decalcification is the
fication scheme. use of 2-10 percent hydrochloric acid. There
This study was commenced on the advice of is also another method in which the specimen
Dr. Takesi Tanaka who possesses a great many is fixed in formalin-alcohol and then decalcified
specimens of Rhodopeltis. An additional col with alcohol to which has been added a certain
lection was made by the author in the Amami amount of acetic acid. Though the methods of
Islands, Mageshima and others. In addition to Inoh (1948) for fixation and decalcification
these, Dr. Yukio Yamada kindly allowed me of Corallinaceae are good, these methods can
to borrow not only the specimens belonging not be used in investigating the development
to Hokkaido University, but also the priceless of the cystocarp of Rhodopeltis because the
specimen of R. australis, Thus I have had an nemathecia of this genus are uncalcified.
opportunity to examine each·of the five known As a decalcifying fixation medium, then,
species. The total number of individual speci Perenyi's solution was found to be most favor
mens examined was 192. able. As a staining medium lactic acid with
Detailed observations were made of the in anilin blue is suitable. With materials stained
ner structure of these specimens, with special in this medium it is easy to distinguish the
attention being given to the examination of vegetative and reproductive cells. As a mount
the reproductive organs, to the clarification of ing medium glycerin or malt jelly with anti
species characteristics, and to a comparative septic is suitable.
examination of the genus as a whole. Fortu All the specimens used in this study were
nately, through the study of the four species, dried. Many of them were put fresh into 10
R. borealis, R. setcbelliae, R. lingoroides, and percent formalin seawater immediately after
R. gracilis, the development of the cystocarp the collection, and then later they were water
and the antheridia was brought out. Therefore, washed and stored in the form of dryherbarium
this study of Rhodopeltis has contributed to specimens.
the appraisal of its systematic position.
SYSTEMATIC REVIEW OFTHE GENUS Rhodopeltis
ACKNOWLEDGMENTS
The genus has been enlarged from time to
Sincere thanks should be offered to Dr. Yu time without any critical review of its charac
kio Yamada, Professor at Hokkaido University, teristics. The author examined the attributes of
who encouraged the.author through his warm each species to facilitate such a review. The
Systematics of Rhodopeltis-NozAwA 101
details in reference to each species are given, 2. Japanese and Philippine R. borealis
following the key that may be used to distin 1. Growing points at the tip of the cylindrical
guish them, on a practical basis, as the author tapered terminal segments; cortical cells elliptical
in all 4 to 5 layers 3
distinguished them for this project.
3. Surface not zonate R. gracilis
KEY TO THE SPECIES OF Rbodopeltis 3. Surface faintly zonate 4
1. Growing points in the terminal notches in tips 4. Lower dichotomies at the basal part complanate
of the flattened terminal segments; cortical cells and broad R. liagoroldes
round in all 7 to 9 layers 2 4. Lower dichotomies at the basal part showing cy-
2. Australian R. australis lindrical tendency R. setchelliae
FIG. 1. A-C, Rbodopeltis borealis Yam. A. Tetrasporophyte (Amami-Oshima); B, female (Amami
Oshima); C, male (Amami-Oshima). D-F, Rbodopeltis setcbelliae Yam. D, Tetrasporophyte (Nakano
shima); E, female (Kasyo-jima); F, male (Kasyo-jima).
102 PACIFIC SCIENCE, Vol. 24, January 1970
Rhodopeltis borealis YAMADA branchlet isuncalcified, showsablood-red color,
and is slightly curved toward the ventral side.
The original description of Rhodopeltis bore
In the mature frond nemathecia may be seen
alis was made by Yamada from specimens col
on the ventral side of the segment at the tip of
lected at Ryusensui and Kotosho in Formosa,
the branch. It is not rare for nemathecia to be
and at Naha in Okinawa (Yamada, 1931).
produced on the ventral side of the second or
This was followed by the reports made con
third segment from the tip.Nemathecia are un
cerning the specimens collected in Yonakuni
calcified, and so theycan be distinguished easily
Jima (Yamada and Tanaka, 1938), Mage
from other parts even with the naked eye (Fig.
shima (Tanaka, 1950), Amami Oshima (Ta
2 C). They are described in detail in the para
naka, 1956), and the Ryukyu Islands (Segawa
graph treating the reproductive organs.
and Kamura, 1960). According to further in
vestigations made by Tanaka it seems that this INNER STRUCTURE: The frond consists of
species is widely distributed over the area ex two parts-the medullary layer composed of
tending from Formosa, the Ryukyu Islands, numerous filamentous cells running longitudi
through the Amami Islands, the Tokara Islands, nally, and the cortical layer composed of spher
and to Mageshima. ical or elliptical cells. The difference between
In this study 86 specimens of R. borealis the dorsal side and the ventral side does not
were used, all of which were dried (Fig. appear in the inner structure.
1 A-C). Cortical layer: As seen in a cross section of
the frond, a cell-row of the cortical layer con
Strnctnre of Thal/tis sists of 8 to 9 cells and can be divided into
OUTER STRUCTURE: Usually the frond is 4-5 outer and inner cortical layers. The cell-rows of
cmhigh, but occasionally some are found which the outer cortical layer usually consist of three
are as large as 7 em. The frond grows fascicu small cells supplied with assimilatory pigments.
lately from a short stem and branches densely Small round cells, 4-5IJ. in diameter, are ar
and dichotomously. Each branch consists of an ranged in a file in the outermost and sub-outer
obconical or oval complanate segment which is most layer. The inner cortical layer consists of
nearly 500IJ. thick, 2-3 mm wide, and 4-7 mm large cells containing no assimilatory pigments.
long. Branching is repeated regularly from the Those innermost are the largest and are round
base of the frond to the top. The size of the cells, 40-50IJ. in diameter, which gradually be
segment remains comparatively uniform to the come smaller toward the outer side (Fig. 2 A,
tip. The frond periphery is strongly calcified B, D). Often many oil-drop-like granules are
and smooth. The color is light purplish red. contained in these cells (Fig. 2 B, I). These
Sometimes orange colored specimens are seen. granules do not stain with anilin blue. A limey
This is due to the coloring of the carbonate precipitation can be observed in all parts of the
deposited over the periphery. At a branch base, cortical layer.
lime is exfoliated, hence this part becomes Medlll/ary layer: The filamentous cells form
slightly constricted forming a node (Fig. 2 ing the medullary layer are 4-8IJ. thick, run
C, G). In some young branches no node for longitudinally, and are ramified. The medullary
mation can be seen. When dried, the thallus filaments, stretching outward at a right angle,
becomes very brittle and tends not to adhere to branch several times dichotomously, and the tip
paper. The branchlet is slightly swollen on its of eachleads to a row of cortical cells.The con
surfaceand, in the dried state, the marginal part nection of the cortical layer cells to the medul
is slightly revolute and a dorsiventral tendency lary filaments is not obvious except in that por
can be recognized. The stem is cartilaginous, tion near thegrowingpoint. The ramifying part
blackish brown, and cylindrical, and the lower of themedullary filamentsnear thecortical layer
end is turned into a discoid root with irregular is enlarged like the node and is stained quite
margins (Fig. 2 H). Irregular branchlets are easily with anilin blue. No limey precipitation
sometimes produced from the dorsal side of the can be seen in the medullary layer (Fig. 2 L).
lower node (Fig. 2 G).The tip of the growing Node: The node is uncalcified and is com-
Systematics of Rhodopeltis-NozAwA 103
--rz.;;;--
C,G,11
FIG. 2. Rbodopeltis borealis, A, Cross section of the the tetrasporangial nemathecium, before decalcifica
tion; B, cross section of the cortical layer of the frond, before decalcification; C, dorsal side of the branch
with carpogonial nemathecia; D, cross section of the female branch with a mature carpogonial nemathecium;
E, longitudinal section of a portion of the vegetative point; F, magnified longitudinal section of E; G, branch
lets proliferating out of the lower segment of the frond, front side; H, basal part of the frond; I, longitudinal
section of the frond; f, longitudinal section of the node; K, longitudinal section of the root; L, cross section
of the root.
104 PACIFIC SCIENCE, Vol. 24, January 1970
A_D,C;,I-M 10)!
E,F 4-0f
H
loof
FIG. 3. Rbodopeltis borealis. A, Unfertilized carpogonial branch; B, connection between the fertilized car
pogonium and the adjoining sterile auxiliary cell; C, same as B, the sterile auxiliary cell is the 4th cell in the
carpogonial branch; D, connection between the fertilized carpogonium which fused with the adjoining sterile
auxiliary cell and the auxiliary cell; E, auxiliary cell branches, carpogonial branches, and cell-rows of nema-
, thecia; F, mature cystocarp; G, auxiliary cell and gonimoblast; H, cross section of the frond with the sperma
tangial nemathecium; I, cross section of the spermatangial nemathecium; f, young stage of the spermatangial
nemathecium; K, tetrasporangial nemathecium; lr-M, young stage of the tetrasporangial nemathecium.
a,Auxiliarycell; co,connecting filament;cp,carpogonium; g,gonimoblast; 12, nemathecial cell-row;sa, sterile
auxiliary cell; sp, spermatangium; I, trichogyne; Is, tetrasporangium.
Systematics of Rhodopeltis-NozAwA 105
posed of ramified medullary filaments of small gonial branch is derived from the apical cell of
size, forming a compact tissue. At first glance, the outermost cortical layer. Usually one carpo
the node of Rhodopeltis borealis resembles the gonial branch is produced from one cell of the
geniculum of Amphiroa, but, judging from the outermost cortical layer, but sometimes this is
inner structure, no special cell arrangement like also accompanied byonecell-rowofsterile cells.
the one seen in the node of Amphiroa isobserv The carpogonial branch stands straight, and the
able (Fig. 2 J). trichogyne grows straightupward, reaching 50
Stem: As in the structure of the node, tough 60ft in length (Fig. 3 A). The auxiliary cell
cartilaginous tissue is formed bya large number branch of 9 to 12 cells grows in the same way
of medullary filaments running both longitudi as the carpogonial branch.Both the carpogonial
nally and horizontally in the stem (Fig. 2 K, branch and the auxiliary cell branch are rich in
L). contents, and prior to fertilization'both of them
Tip-end: No calcification can be seen near can easily be distinguished from the cell-rows
the vegetative (growing) point of the young of the nemathecia (Fig. 3 E). There are far
branchlet, and sections of the dichotomously more auxiliary cell branches than carpogonial
branching filaments show a typical multiaxial branches.
structure. In relation to the distance from the After fertilization, the carpogonium fuses
vegetative point, these filamentous cells become with the sterile auxiliary cell (or nutritive cell)
gradually spherical, and in forming the cortex of thesamecarpogonial branch. Thesterile aux
there is a simultaneous precipitation of lime iliary cell is usually the cell next to the carpo
(Fig. 2 E, F) . gonium but may be the third or fourth cell back
from the carpogonium (Fig. 3 B, C). Where
Reproductive Organs the cell next to the carpogonium is the sterile
auxiliary cell, there is an immediate disappear
DEVELOPMENT OF CYSTOCARP: Carpogonial
ance of the cell membrane between these two
nemathecia are sometimes about 1.5 X 3-4 mm
cells (Fig. 3 D). Compared with other cells in
in diameter and elliptical, and sometimes they
the carpogonial branch no notable difference
are about 2 X 2 mm in diameter and round.
can be seen in the sterile auxiliary cell. The
Theyappear on the surfaceof the frond as red
carpogonium, after fusing with the sterile aux
dish brown dots, and are uncalcified.The nerna
thecia grow out of the ventral side of the seg iliary cell, dispatches a connecting filament to
ward the auxiliary cell of the auxiliary cell
ment either at the top of the frond or at the
branch. The position of the auxiliary cell is not
second or third segment of that frond. The
fixed, but generally it appears in the center of
nemathecia, however, do not grow from young
the cell-row, the fourth or fifth cell from the
branchlets or from the branchlets growing from
tip. When the connecting filament reaches the
the basal part of the branch. Usually one nerna
auxiliary cell, its tip enlarges, and from this en
thecium is attached to one segment, but rarely
larged end a long cell is cut off and fuses with
two small nemathecia are seen. Mature nema
the auxiliary cell, forming a process which ex
thecia may be 200ft in diameter and project
tends out of the auxiliary cell-row. From this
from the surface (Fig. 2 D).
enlarged fusion cell the several primary goni
The cell-rows of the nemathecia are produced
moblast cells are separately divided toward the
from the outermost cells of the cortical layer,
surface (Figs. 3 D and 4 A-F). Each gonimo
each cortical cell producing two rows. The cell
blast initial continues to divide and produces a
row consists of 13 to i5 cells and is not rami
single carpospore terminally (Figs. 3 G and 4
fied. In the mature cell-rows, the middle cells
of each row are elongate and stretched; the ter G, H). Each carpospore is 6-8 X 12-15ft. The
cystocarp has no pericarp. Connecting filaments
minal cells are round and small, with a thick
may branch repeatedly, seeking other auxiliary
cell membrane. Both carpogonial and auxiliary
cells. Occasionally a continuation of the con
cell branches grow interspersed among the nern
necting filament is seen, presumably to other
athecia cell-rows. The carpogonial branch usu
auxiliary cells (Fig. 4 A).
ally consists of 6 to 8 cells, rarely of 5. As in
the case of the vegetative cell-rows, the carpo- DEVELOPMENT OF SPERMATANGIUM: Sper-
106 PACIFIC SCIENCE, Vol. 24, January 1970
A -H
15f
I
G~
F
FIG. 4. Rbodopeltis borealis. A, auxiliary cell which fused with a first connecting filament and two secon
dary connecting filaments; B-F, young stages of the gonimoblast; G, a more advanced stage of F; H,gonimo
blast producing carpospores,
a, Auxiliary cell; co, connecting filament; co2, second connecting filament; ca, carpospore; g, gonimoblast.
matangial nemathecia are 1-2 rnm in diameter, in the outermost periphery of the cortical layer
elliptical, somewhat smaller than the female become elongated vertically, and then this is
nemathecia, 70-100f! thick, uncalcified, and divided into the two parts, upper and lower, by
colorless. In the dried specimen its slight luster horizontal division. The upper one is uncalci
is the sole clue for distinguishing it from other fied, and becomes the original cell of a nerna
parts. Nemathecia areproduced in asimilarway thecium. It contains no pigments. After irregu
to that of the carpogonial ones (Fig. 3 H).The lar dichotomous divisions, a nemathecium con
formation of this structure is as follows: Cells sisting of slender colorless branchlets, with mi-
Systematics of Rhodopeltis-NoZAWA 107
nutely ramified tip-ends is formed. Several cells Strnctsre of Thallus
in arow at the tip-end of the respective branches OUTER STRUCTURE: Someexternal differences
become spermatangia. The periphery of nerna can be seen between the specimens collected at
thecia is covered with the transparent cuticle Kasyo-to in Formosa and at Nakanoshima in
like layer, and spermatangia lie buried in the
Kagoshima Prefecture, but no difference is ob
layer (Fig. 3 t, 1). served in the internal structure. The specimen
collected in Kasyo-to may be described as fol
.DEVELOPMENT OF TETRASPORANGIUM: Tet
lows: Frond 5-7 em high, from a short stem,
rasporangial nemathecia are nearly 1.5 X 3
branching densely, fasciculately, and dichoto
mrn in diameter, elliptical, and appear at sim
mously. Lower branches of the frond compla
ilar locations to those seen in male and female
nate, being 1.8-2 mm wide, nearly 5 mm long,
thalli. They are reddish brown in color, uncal
about 800f,l thick, and at the dichotomies they
cified, and at first glance are barely distinguish
may be 3-4 mm wide. The branches taper to
.able from the carpogonial nemathecia. Tetra
ward their tips, becoming cylindrical, the ulti
sporangialnematheciaareusually 50-6of,l,some
mate branchlets 2-3 mm long with somewhat
times 70f,l,and are far thinner than carpogonial
sharpened apex. In dried specimens the cylin
nemathecia (Fig. 2 A). They are formed in the
drical branchlets are furrowed longitudinally
following way: At first, the cell in the outer
(Fig. 5 A). In the specimen collected in Na
most periphery of the cortical layer assumes an
kanoshima the basal part of the frond is less
elliptical shape, pointed at its tip-end; then it is
densely branched than those collected in Kasyo
divided into two parts by horizontal division.
to.Some of these fronds are 10 em high, and
The lower cells remain part of the cortical layer
the branching angle at.the basal part is wider
and become calcified, but these cells are some
than in those from Kasyo-to (Fig. 5 B, C).
what longer than the ordinary frond cells and
The peripheryof the fronds is covered with
are arranged in a palisade row. The upper cell
lime, but the precipitation of lime is not as
is uncalcified, and after stretching out through
abundant as in R. borealis. The lime is richer
the cortical layer becomes the original cell of a
in the upper part of the frond than in the
nemathecium. This is either elongated in accor
lower. The color is scarlet purple. The thalli
dance with this original shape or forms un
are brittle and do not adhere to paper. Weak
branched cell-rows consisting of 2 to 4 cells.
transverse striations can be seen on the surface
Sometimestwonemathecia-generatingcellsgrow
of the frond. The stem is 1-2 mm long, and
from one outermost cortical cell. The first cell
nearly 600f,l-1 mm in diameter basally, forming
of the nemathecium is directly turned into a
an irregular disclike holdfast (Fig. 5C). Nodes
tetrasporangium by enlarging, and the contents
are formed irregularly. The growing tips are
become rich and zonately divided. A tetraspor
slightly sharpened, show a somewhat dense
angium measures 8-12 X 30f,l,and they are ar
color, and are uncalcified. Nemathecia are dark
ranged in a single row within the nemathecium.
purple and uncalcified and grow at random on
The periphery of the nemathecium is covered
the upper branchlets. Details concerning nema
with acolorless cuticle-like layer (Fig. 3L,M).
thecia are explained in the paragraph describing
the reproductive organs.
Rbodopeltis setcbelliae YAMADA
INNER STRUCTURE: The frond can be di
A study of Rhodopeltis setcbelliaewas made vided into the medullary layer consisting of
from specimens collected at Kasyo-to, Formosa, many longitudinal filaments, and the cortical
by Yamada (1935a). This was followed by a .layer consisting ofspherical or elliptical cells.
report of specimens collected in the Ryukyu Is Cortex: Thecortical layer isusually composed
lands (Segawa and Kamura, 1960), and since of 4 to 5 cellsand can be roughly divided into
then a collection of this species was also made an outer layer consisting of small cells contain
at Nakanoshima and Takara Jima in Kagoshima ing assimilatory pigments and an inner layer
Prefecture. Twenty-two dried specimens were of large cells containing no assimilatory pig
used in this study (Fig. 1 D-F). ments. The outer cortex usually consists of 2
108 PACIFIC SCIENCE, Vol. 24, January 1970
:F,ll
A-C
FIG. 5. Rbodopeltis setcbelliae. A, Branch with carpogonial nemathecia; B, branch with tetrasporangial
nemathecia; C, root part of thetetrasporangial frond; D, cortical layer cells of the frond; E, same as D, before
decalcification; F, cross section of branch with a carpogonial nemathecium, before decalcification; G, longitu
dinal section of the tip-end of a branchlet; H, cross section of the carpogonial nemathecium.
cell-rows, the outermost being uncalcified and the cell sizes observable in the calcified outer
consistingof oblong, elliptical, or obconical cells cortical layer. Lime precipitation decreases to
5-6 X 1511in size. The cell membrane is thick ward the center of the inner layer (Fig. 5 D,
ened and supplied with a lot of assimilatory E, F) and disappears completely in the me
red pigments (Fig. 5E). The 2 to 3 outermost dulla.
cortical cells are borne on a layer of calcified Medulla: The medullary layer consists of
cells (Fig. 5D).These calcifiedcellsare of var branched filaments, 6-811 thick, intertwined,
ious sizes and shapes, being spherical, with a and directed periclinally. The medullary fila
diameter of 411, to elliptical, measuring lO X ments branch anticlinally, and the cells assume
2011. More abundant assimilatory pigments and a different shape as they become part of the
lime precipitation can be seen in the smaller cortex. The transition between the medullary
spherical cells than in the large elliptical ones. filaments and cortical cells ismore obvious than
The inner cortical layer consists of 2 to 3 cells, in the case of R. borealis (Fig. 5 D, F).
usually 3, the innermost being 50-60 X 60 As in R. borealis the node consists of the
8011 and elliptical. The slight transverse stria minute entanglements of medullary filaments.
tions may be due, perhaps, to the difference in The growing portion of the young branches