ULTRASTRUCTURE OF AUXILIARY AND GONIMOBLAST CELLS DURING CARPOSPOROPHYTE DEVELOPMENT IN FAUCHEOCOLAX ATTENUATA (RHODOPHYTA)1

The ultra structure of post-fertilization development in Faucheocolax attenuata Setch. is described. Following fertilization and transfer of the diploid nucleus to the auxiliary cell, four gonimoblast initials usually are produced of the multinucleate auxiliary cell. Gonimoblast initials originally are uninucleate but undergo karyokinesis to form multinudeate gonimoblast cells. Terminal or generative gonimoblast cells cleave successively to form lobes of incipient carpospores, with each group of spores differentiating synchronously. Portions of the initial generative gonimoblast cells, however, remain to resume karyokinesis and repeat the process of cleavage into carpospores. Axial gonimoblast cells are transformed into secretory cells, which produce mucilage. Generative gonimoblast cells and auxiliary cells are similar in cellular structure. Both contain typical red algal proplastids, some dictyosomes, cytoplasmic concentric membranes, and numerous small vesicles. In addition, dark staining spherical masses, occurring in the cytoplasm of all cell types, may represent dehydrated haploid chromatin. Large septal plugs interconnect gonimoblast cells and the auxiliary cell. These plugs are small when first formed but increase dramatically in size during carposporophyte development.     

Ultrastructure of post-fertilization development in the red alga Nienburgia andersoniana (Delesseriaceae, Ceramiales, Rhodophyta)

The ultrastructure of post-fertilization development in Nienburgia andersoniana (J. Ag.) Kyl. is described. Above the auxiliary cell there is a group of four sterile cells. The presence of abundant storage products (starch granules, lipid bodies and protein crystals) in these cells indicates that the sterile cells function as nutrient suppliers to the young auxiliary and gonimoblast cells of the carposporophyte during its early steps of development. Following fertilization and transfer of the diploid nucleus to the auxiliary cell, the trichogyne disappears and large multinucleate gonimoblast initials are produced. These subsequently produce generative gonimoblast cells which cleave successively to form young carpospores. Those of the gonimoblast cells which will not differentiate into carpospores are transformed into cells producing mucilage. Both kinds of gonimoblast cells contain plastids, starch granules, cytoplasmic concentric membrane bodies and small vesicles. Dark-staining spherical masses occurring in the cytoplasm of the auxiliary and gonimoblast cells may represent degenerating haploid nuclei. Septal plugs interconnecting the auxiliary cell and gonimoblast cells increase considerably in size during carposporophyte development. The fusion cell at the late stage of carposporophyte development appears degenerative. Young carpospores have plastids and mitochondria, and concentric membrane bodies that will form mucilage sacs. Medium-aged carpospores have fully developed plastids, starch granules and fibrous vacuoles. Mature carpospores possess, in addition, cored vesicles. The inner pericarp cells contribute large amounts of mucilage to the cytostocarpic cavity and eventually are consumed. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 289–299.     

Ultrastructure of post-fertilization development in the red alga Scinaia articulata (Galaxauraceae,Nemaliales, Rhodophyta)

The ultrastructure of the carposporophyte and carposporogenesis is described for the red alga Scinaia articulata Setch. After fertilization, the trichogyne disappears, and the pericarp develops to form a thick protective tissue that surrounds the carposporophyte. The hypogynous cell cuts off both one-celled and two-celled sterile branches. Patches of chromatin are frequently observed in evaginations of the nuclear envelope, which appear to produce vesicles in the cytoplasm of the cell of the sterile branch. Large gonimoblast lobes extend from the carpogonium and cleave to form gonimoblast initials. Subsequently, a fusion cell is formed from fusions of the carpogonium, the hypogynous cell and the basal cell of the carpogonial branch. The mature carposporophyte comprises the fusion cell that is connected to the sterile branch cells, gonimoblast cells and carpospores and is surrounded by extensive mucilage. Young carpospores possess a large nucleus and proplastids with a peripheral thylakoid, but they have few dictyosomes and starch granules and are indistinguishable from gonimoblast cells. Subsequently, dictyosomes are formed, which produce vesicles with an electron-dense granule, which indicates an initiation of wall deposition. Thylakoid formation coincides with incipient starch granule deposition. The nuclear envelope produces fibrous vacuoles and concentric membrane bodies. Carpospores are interconnected by pit connections with two cap layers. Dictyosome activity increases, resulting in the production of vesicles, which either continue to deposit wall material or coalesce to form fibrous vacuoles. The final stage of carposporogenesis is characterized by the massive production of cored vesicles from curved dictyosomes. Mature carpospores are uninucleate and contain fully developed chloroplasts, numerous cored vesicles, numerous starch granules and fibrous vacuoles. The mature carpospore is surrounded by a wall layer and a separating layer, but a carposporangial wall is lacking.     

ULTRASTRUCTURE OF CARPOSPOROGENESIS IN THE PARASITIC RED ALGA FAUCHEOCOLAX ATTENUATA SETCH. (RHODYMENIALES,RHODYMENIACEAE)

Carpospore differentiation in Faucheocolax attenuata Setch. can be separated into three developmental stages. Immediately after cleaving from the multinucleate gonimoblast cell, young carpospores are embedded within confluent mucilage produced by gonimoblast cells. These carpospores contain a large nucleus, few starch grains, concentric lamellae, as well as proplastids with a peripheral thylakoid and occasionally some internal (photosynthetic) thylakoids. Proplastids also contain concentric lamellar bodies. Mucilage with a reticulate fibrous substructure is formed within cytoplasmic concentric membranes, thus giving rise to mucilage sacs. Subsequently, these mucilage sacs release their contents, forming an initial reticulate deposition of carpospore wall material. Dictyosome vesicles with large, single dark-staining granules also contribute to wall formation and may create a separating layer between the mucilage and carpospore wall. During the latter stages of young carpospores, starch is polymerized in the perinuclear cytoplasmic area and is in close contact with endoplasmic reticulum. Intermediate-aged carpospores continue their starch polymerization. Dictyosomes deposit more wall material, in addition to forming fibrous vacuoles. Proplastids form thylakoids from concentric lamellar bodies. Mature carpospores are surrounded by a two-layered carpospore wall. Cytoplasmic constituents include large floridean starch granules, peripheral fibrous vacuoles, mature chloroplasts and curved dictyosomes that produce cored vesicles which in turn are transformed into adhesive vesicles. Pit connections remain intact between carpospores but begin to degenerate. This degeneration appears to be mediated by microtubules.     

THE ULTRASTRUCTURE OF CARPOSPOROGENESIS IN THE MARINE HEMIPARASITIC RED ALGA ERYTHROCYSTIS SACCATA1

The ultrastructure of carposporogenesis for Erythrocystis saccata is described. The fusion and gonimoblast cells contain few organelles, and chloroplasts are in a proplastid state, with pit plugs between gonimoblast cells dissolving early in development. Carpospore development may be separated into 3 stages, the first stage being characterized by the appearance of straight-profiled dictyosomes, fibrous vesicles, and an increase of discoid thylakoids within the chloroplasts. During the second, stage the dictyosomes assume a curved profile and striped vesicles are formed by the endoplasmic reticulum. The third stage is initiated by the disappearance of striped vesicles and the appearance of straight-profiled dictyosomes secreting vesicles with cores. Mature carpospores consist of many cored vesicles, fibrous vesicles, and floridean starch grains. A single wall layer surrounds each carpospore since the carposporangial wall becomes incorporated into a mucilaginous matrix surrounding the spores.     

Ultrastructure of auxiliary and gonimoblast cells during carposporophyte development in the red alga Cryptopleura ruprechtiana (Delesseriaceae, Ceramiales, Rhodophyta)

The ultrastructure sequence for the complete post-fertilization development is described in Cryptopleura ruprechtiana (C. Agardh) Kylin, a member of the Delesseriaceae. Following fertilization the diploid nucleus is transferred to the auxiliary cell. This contains typical red algal proplastids, cytoplasmic concentric membranes, numerous small vacuoles and lipid bodies. Crystalline inclusions and virus-like particles are also present. In addition darkly staining spherical masses possibly represent dehydrated haploid chromatin. The multinucleate auxiliary cell produces initially one large gonimoblast initial and subsequently many smaller gonimoblast initials. The first formed generative gonimoblast cell is similar in cellular structure to the auxiliary cell. Gonimoblast initials are uninucleate but through caryokinesis they become multinucleate. They undergo repeated cleavage to form more gonimoblast cells. Subsequent, centripetal cytokinesis results in the formation of clusters of gonimoblast cells. A new type structural cap or association is observed in the septal plugs that interconnect gonimoblast initials. Terminal or generative gonimoblast cells cleave to form additional gonimoblast cells. Only terminal gonimoblast cells are differentiated to carpospores.     

ULTRASTRUCTURE OF THE CARPOSPOROPHYTE AND CARPOSPOROGENESIS IN THE PARASITIC RED ALGA PLOCAMIOCOLAX PULVINATA SETCH, (GIGARTINALES,PLOCAMIACEAE) 1

The ultrastructure of the carposporophyte and carposporogenesis is described for the parasitic red alga Plocamiocolax pulvinata Setch. After presumed fertilization the zygote nucleus is apparently transferred to the auxiliary cell which initiates gonimoblast cell production. These gonimoblast cells differentiate into storage or generative cells. Storage gonimoblast cells (SGC) are large and multinucleate, contain large quantities of starch and are located nearest the auxiliary cell, when compared to the smaller uninucleate, devoid of starch, generative gonimoblast cells (GGC) that form terminal lobes of carpospores. In addition, compressed membrane bodies and annulate lamellae are common in these cells. During carposporophyte maturation the amount of starch in the SGC's decreases and eventually the auxiliary cell, as well as SGC's, degenerate. Generative gonimoblast cells (GGC's) cleave repeatedly to form carpospores which are interconnected by small pit connections. Stage one-carpospores are recognized by their elongated shape, the formation of small     

Ultrastructure of the early stages of carposporophyte development in the red algaChondria tenuissima (Rhodomelaceae,Ceramiales)

The ultrastructure of the early stages of carposporophyte development in the marine red algaChondria tenuissima has been studied. The diploid carposporophyte grows on the gametophyte. Apical gonimoblast cells develop into diploid carpospores. The basal gonimoblast cells cease to divide and undergo considerable cytoplasmic changes before they become incorporated into the expanding fusion cell. Nucleus and plastids degenerate gradually, while mitochondria remain intact. The smooth endoplasmic reticulum becomes prominent, it seems to produce small vesicles with electron dense contents. Simultaneously, numerous mucilage sacs are formed, presumably from dilating ER cisternae. The contents of the mucilage sacs are secreted by exocytosis. The pit connections between gonimoblast cells flare out. They remain as isolated bodies without connection to a wall after fusion. Secondary pit connections occur between vegetative gametophyte cells and sterile carposporophyte cells. There are three different morphological types of pit connections.     

LIGHT AND ELECTRON MICROSCOPIC STUDIES OF THE FUSION CELL IN ASTEROCOLAX GARDNERI SETCH. (RHODOPHYTA,CERAMIALES)12

The fusion cell in Asterocolax gardneri Setch, is a large, multinucleate, irregularly-shaped cell resulting from cytoplasmic fusions of haploid and diploid cells. Subsequent enlargement takes place by incorporating adjacent gonimoblast cells. The resultant cell consists of two parts—a central portion of isolated cytoplasm, surrounded by an electron dense cytoplasmic barrier, and the main component of the fusion cell cytoplasm surrounding the isolated cytoplasm. The fusion cell contains many nuclei, large quantities of floridean starch, endoplasmic reticulum, and vesicles, but few mitochondria, plastids and dictyosomes. The endoplasmic reticulum forms vesicles that apparently secrete large quantities of extracellular mucilage which surrounds the entire carposporophyte. The isolated cytoplasm also is multinucleate but lacks starch and a plasma membrane. Few plastids, ribosomes and mitochondria are found in this cytoplasm. However, numerous endoplasmic reticulum cisternae occur near the cytoplasmic barrier and they appear to secrete material for the barrier. In mature carposporophytes, all organelles in the isolated cytoplasm have degenerated.     

An ultrastructural study of carpospores in the red alga <Emphasis Type="Italic">Chondrus pinnulatus</Emphasis> (Harvey) okamura, 1930 (Rhodophyta: Gigartinaceae) from Vostok Bay,the Sea of Japan

The morphological features of carpospores in the red alga Chondrus pinnulatus have been studied using methods of transmission and scanning electron microscopy. Rounded mature carpospores are assembled into groups. Each carpospore is surrounded by a two-layered mucilage wall. The electron-dense cytoplasm contains numerous starch grains, fibrous vesicles, and large clusters of fibrous vesicles. The plastids have well-developed thylakoids and the cell nucleus occupies a nearly central position. The nucleolus is large and loose and is localized near the nuclear membrane. Dictyosomes, small fibrous vesicles, osmiophilic granules, and plastids are localized at the periphery. Mitochondria are arranged near the dictyosomes, plastids, and around the nucleus. A generalized scheme of the fine structure of the carpospore has been proposed for red algae on the basis of our own and literature data.     

A Light Microscope Study of Carposporophyte Development in Gracilaria verrucosa (Hudson) Papenfuss

Gracilaria verrucosa is a very common marine red alga of Greekcoasts. The diploid carposporophyte which develops attachedto the female gametophyte of Gracilaria is described. The immaturecystocarps are very small while the mature ones are globose,ostiolate and are borne profusely all over the surface of thethallus. The earliest observed fusion cell is small and fusesprogressively with adjacent vegetative cells to form a largemultinucleate cell. From this fusion cell gonimoblast initialsoriginate, dividing further and giving rise to a large numberof gonimoblast cells. The resultant carposporophyte consistsof a basal-central, multinucleate cell surrounded by a conicalor hemispherical mass of gonimoblast cells. Chains or clustersof successively maturing carpospores are borne from the terminalgonimoblast cells. The liberation of mature carpospores takesplace through the ostiole of the cystocarp. The liberated carposporeslack cell walls and are naked in a mucilage mass. Gracilaria verrucosa (Hudson) Papenfuss, Gigartinales, Gracilariaceae, Rhodophyta, carposporophyte, development     

LEACHIELLA PACIFICA,GEN. ET SP. NOV., A NEW PARASITIC RED ALGA FROM WASHINGTON AND CALIFORNIA

Leachiella pacifica, gen. et sp. nov., a marine alloparasitic red alga is described from Washington and California. Several species of Polysiphonia and Pterosiphonia are hosts for this parasite. The thallus is a white, multiaxial, unbranched pustule with rhizoidal filaments that ramify between host cells, forming numerous secondary pit connections with host cells. All reproductive structures develop from outer cortical cells. Tetrasporocytes, situated on stalk cells, undergo simultaneous, tetrahedral cleavage to form tetraspores. Spermatia are formed continuously by oblique cleavages of the elongate spermatial generating cells. This results in spermatial clusters consisting of 4–8 spermatia in an alternate arrangement. Carposporophyte development is procarpial. The carpogonium is part of a six-celled branch including a sterile cell that is formed by the basal cell. The carpogonial branch is attached laterally to an obovate supporting cell that also forms an auxiliary cell, presumably formed prior to fertilization. After fertilization the carpogonium temporarily fuses with the auxiliary cell apparently to transfer the diploid nucleus and initiate further fusion with the subtending supporting cell to form an incipient fusion cell. The auxiliary cell portion of this fusion cell divides to form gonimoblast initials that continue to divide, forming gonimoblast filaments whose terminal cells differentiate into carpospores. The remainder of the fusion cell enlarges by continual fusion with adjacent vegetative cells. The resultant carposporophyte consists of a basal, multinucleate fusion cell supporting a hemispherical cluster of gonimoblast filaments with terminally borne carpospores. Vegetatively, Leachiella resembles several other parasitic red algae but it is clearly separated by the procarp, carposporophyte development and structure, and tetrasporocyte cleavage.     

ULTRASTRUCTURE OF TETRASPOROGENESIS IN PALMARIA PALMATA (RHODOPHYTA)1

The tetrasporangial initial in Palmaria palmata (L.) O. Kuntze (formerly Rhodymenia palmata (L.) Greville) arises from a cortex cell which enlarges and deposits a protein-rich wall layer. This cell undergoes mitosis to form a tetrasporocyte and a stalk cell. Synaptonemal complexes are formed in the sporocyte nucleus while in the cytoplasm floridean starch is deposited in association with ER or with particles presumed to be ribosomes. Microbody-like structures become numerous between the nuclear envelope and perinuclear ER, and clusters of non-membranous, spherical structures also are associated with the nucleus. Chromatin condensation is reversed following pachytene and a prolonged diffuse stage ensues, when dictyosomes and ER produce vesicles which deposit mucilage rich in sulfated and acidic polysaccharides around the tetrasporocyte. A conspicuous lenticular thickening of the mucilage sheath develops at the apical end of the sporangium. Dictyosomes are frequently associated with mitochondria which may be associated with chloroplasts. Following nuclear divisions the tetrasporocyte is cleaved into four spores by sequentially initiated, but simultaneously completed periclinal and anticlinal furrows. When mucilage deposition ceases, the dictyosomes begin to produce vesicles with glycoprotein-rich contents. These vesicles are abundant in released tetraspores, and they probably contain adhesive material aiding in the attachment of the liberated spores.     

STRUCTURE AND DEVELOPMENT OF THE CARPOSPOROPHYTE OF NEMALION HELMINTHOIDES (NEMALIONALES,RHODOPHYTA)1

Following fertilization, the carposporophyte of Nemalion helminthoides (Velley in With.) Batters differentiates into four distinct regions: the fusion cell, the sterile gonimoblast cells, the carposporangial mother cells and the carposporangia. The gonimoblast is formed by apically dividing, monopodial filaments of limited growth which may later become pseudodichotomous. Upon differentiation of a terminal carposporangium, a gonimoblast filament may continue to grow sympodially. A single carposporangial mother cell may produce carposporangia in several different directions as well as proliferate successive carposporangia within the sporangial walls that remain after carpospore liberation. As the carposporophyte matures, the gonimoblast initial, the stalk cell, the hypogynous and subhypogynous cells fuse. Except for the fusion cell, all cells of the carposporophyte show organelle polarity and contain a distally located, lobed chloroplast and proximal nucleus.     

ULTRASTRUCTURE OF GERMINATING CARPOSPORES OF PORPHYRA VARIEGATA (KJELLM.) HUS (BANGIALES,RHODOPHYTA)1

The fine structure of released, attached, and germinating carpospores of Porphyra variegata (Kjellm.) Hus is described. Adhesive vesicles, formed during sporogenesis and discharged upon settling of the spore, produced a layer of adhesive mucilage around the spore and filled a deep imagination on the spore's ventral side. The mucilage layer was punctured by the emergence of a germ tube. Both spore and germ tube were lined by newly deposited cell wall. Germination was accompanied by vacuolation and starch mobilization. The morphological development of the sporeling was not noticeably influenced by the great variability of the timing, location, and orientation of septum formation. The attached carpospore possessed a plastid like that of gametophyte cells: stellate with one large central pyrenoid and no peripheral encircling thylakoids. Cells of mature vegetative cells of the conchocelis had plastids that were elongate and parietal and had multiple pyrenoids and encircling thylakoids. Most stages in the transition between the two forms of plastids occurred during carpospore germination.     

Ultrastructure of the differentiating zygotospores of Porphyra leucosticta (Rhodophyta)

The ultrastructure of zygotosporogenesis is described for the red alga Porphyra leucosticta Thuret. Packets of eight zygotosporangia, each packet derived from a single carpogonium are interspersed among vegetative cells. Zygotospore differentiation in Porphyra can be separated into three developmental stages. (i) Young zygotospores exhibit a nucleus and a large centrally located, lobed plastid with pyrenoid. Mucilage is produced within concentric membrane structures during their dilation, thus resulting in the formation of mucilage sacs. Subsequently, these sacs release their contents, initiating the zygotospore wall formation. Straight‐profiled dictyosomes produce vesicles that also provide wall material. During the later stages of young zygotospores, starch polymerization commences, (ii) Medium‐aged zygotospores are characterized by the presence of fibrous vacuoles. These are formed from the ‘fibrous vacuole associated organelles’. The fibrous vacuoles finally discharge their contents. (iii) Mature zygotospores are recognized by the presence of numerous cored vesicles produced by dictyosomes. Cored vesicles either discharge their contents or are incorporated into the fibrous vacuoles. There is a gradual reduction of starch granules during zygotospore differentiation. Mature zygotospores are surrounded by a fibrous wall, have a large chloroplast with pyrenoid and well‐depicted phycobilisomes but are devoid of starch granules.     

Acid phosphatase activity during spore differentiation of the red algaeGigartina teedii andChondria tenuissima

The acid phosphatase activity during carposporogenesis inGigartina and tetrasporogenesis inChondria was studied using the Gomori technique. During the first steps of gonimoblast maturation ofGigartina, portions of cytoplasm are ensheathed by ER cisternae with acid phosphatase activity, giving rise to autolysosomal concentric membrane bodies. In a similar way large mucilage sacs are severed. They extrude their contents in a kind of exocytosis. Multivesicular bodies, concentrically arranged cisternae and extracytoplasmic compartments, each with acid phosphatase activity, remain in young carpospores for some time, probably as remnants of the autophagocytotic and exocytotic events. The Golgi apparatus is poorly developed in gonimoblast cells and young carpospores. It becomes a prominent cell component in maturing carpospores and then participates in cell wall formation. Only some of the dictyosomal cisternae contain acid phosphatase; these are irregularly distributed in the dictyosome. — In pre- and postmeiotic tetraspore mother cells ofChondria massive lead deposits are found in the dictyosomes and in adjacent Golgi vesicles. Finer lead precipitates occur in ER cisternae, especially in those which are sequestering starch-grain-containing portions of the cytoplasm to give rise to autolysosomes. During cell cleavage, the dictyosomes aggregate. They become devoid of acid phosphatase activity with the exception of vesicles at the trans face. Later, Golgi stacks associate and have common, Gomori positively reacting, narrow cisternae at the cis face. The Golgi apparatus derived cored vesicles do not contain lead precipitates whereas the Golgi cisternae in the final stage of tetrasporogenesis show acid phosphatase activity. Variations in acid phosphatase distribution are explained in the light of current models of membrane flow.Dedicated to Univ.-Prof. DrO. Härtel on the occasion of his 80th birthday.     

ANALYSIS OF MUCILAGE SECRETION AND EXCRETION IN MICRASTERIAS (CHLOROPHYTA) BY MEANS OF IMMUNOELECTRON MICROSCOPY AND DIGITAL TIME LAPSE VIDEO MICROSCOPY1

Two different, independent, and alternative modes of mucilage excretion were found in the unicellular green alga Micrasterias denticulata Bréb. under constant culture conditions. The cells were capable of either excreting mucilage over all their cell surface or they extruded mucilage from one of their polar ends, which enabled directed movement such as photoorientation or escape from unfavorable environmental conditions. By means of a polyclonal antibody raised against Micrasterias mucilage, the secretory pathway of Golgi derived mucilage vesicles from their origin to their discharge was analyzed by means of conventional and energy filtering TEM. Depending on the stage of the cell cycle, mucilage vesicles were subjected to maturation processes. This may occur either after they have been pinched off from the dictyosomes (e.g. during cell growth) or when still connected to trans‐Golgi cisternae, as in the case of interphase cells. Only fully grown mature vesicles contained mucilage in its final composition as indicated by antibody labeling. After fusion of mucilage vesicles with vacuoles, no immunolabeling was found in vacuoles, indicating that the vesicle content was digested. Mucilage vesicles fused with the plasma membrane in areas of cell wall pores but were also able to excrete mucilage at any site directly through the respective cell wall layer. This result disproves earlier assumptions that the pore apparatus in desmids are the only mucilage excreting areas at the cell surface. Both mechanisms, excretion through the pores and through the cell wall, lead to formation of mucilage envelopes covering the entire cell surface.     

A NEW METHOD OF CYSTOCARP DEVELOPMENT IN THE RED ALGAL GENUS CALLOPHYLLIS (KALLYMENIACEAE) FROM CHILE1

Traditional studies suggest that the Kallymeniaceae can be divided into two major groups, a nonprocarpic Kallymenia group, in which carposporophyte formation involves an auxiliary cell branch system separate from the carpogonial branch system, and a procarpic Callophyllis group, in which the carpogonial branch system gives rise to the carposporophyte directly after fertilization. Based on our phylogenetic studies and unpublished observations, the two groups each contain both procarpic and nonprocarpic genera. Here, we describe a new method of reproductive development in Callophyllis concepcionensis Arakaki, Alveal et Ramírez from Chile. The carpogonial branch system consists of a supporting cell bearing both a three‐celled carpogonial branch with trichogyne and two‐lobed “subsidiary” cells. After fertilization, large numbers of secondary subcortical and medullary cells are produced. Lobes of the carpogonial branch system cut off connecting cells containing enlarged, presumably diploid nuclei that fuse with these secondary vegetative cells and deposit their nuclei. Derivative enlarged nuclei are transferred from one vegetative cell to another, which ultimately cut off gonimoblast initials that form filaments that surround the central primary medullary cells and produce carposporangia. The repeated involvement of vegetative cells in gonimoblast formation is a new observation, not only in Callophyllis, but in red algae generally. These results call for a revised classification of the Kallymeniaceae based on new morphological and molecular studies.     

THE ULTRASTRUCTURE OF CARPOSPOROGENESIS IN CALOGLOSSA LEPRIEURII (DELESSERIACEAE,CERAMIALES)

Carposporogenesis in Caloglossa leprieurii is divided into three cytological stages. At stage I, the young spores have few plastids and little starch. Abundant dictyosomes secrete a gelatinous wall layer in scale-like units. At stage II, dictyosomes produce a second fibrillar wall component in addition to the gelatinous constituent. Large fibrillar vesicles accumulate in the cytoplasm. Production of gelatinous material decreases in this stage. By stage III, starch grains and fully developed plastids are abundant. Rough endoplasmic reticulum occupies much of the peripheral cytoplasm. A dense, granular proteinaceous component appears in the wall in association with the fibrillar layer. Arrays of randomly oriented tubules are scattered in the cytoplasm. The mature carpospore is surrounded by an outer gelatinous wall layer and an inner fibrillar layer. Few dictyosomes persist in the mature spore. Carposporogenesis in Caloglossa is compared with that in other red algae.