POLLEN MORPHOLOGY AND THE RELATIONSHIPS OF CIRCAEASTER,OF KINGDONIA,AND OF SARGENTODOXA TO THE RANUNCULALES

The pollen of three monotypic genera, Circaeaster, Kingdonia, and Sargentodoxa has been examined by light and scanning electron microscopy and in the case of the last genus, also by transmission electron microscopy. The type of tectum found in Circaeaster and Kingdonia, derivations of a compound layer of striae, has a restricted distribution in the Order Ranunculales. Of 64 genera examined in this order only six had species with a similar tectum. They include Achlys, Epimedium, Jeffersonia, and Vancouveria of the Berberidaceae s.l., the controversial Hydrastis, and Trollius of the Ranunculaceae. Circaeaster and Kingdonia have been considered as related since both have rare and primitive vegetative characteristics, the most notable being open dichotomous leaf venation. They are probably best treated as a ditypic family, Circaeasteraceae. The pollen of Sargentodoxa, especially the structure of the exine, closely resembles that of the Lardizabalaceae. However, the fruits of Sargentodoxa have been considered to be distinct from those of the Lardizabalaceae, suggesting that it be treated as a separate, but closely allied, family.     

THE ULTRASTRUCTURE AND MORPHOLOGICAL VARIABILITY OF THE FRUSTULE OF STEPHANODISCUS INVISITATUS HOHN AND HELLERMAN1

Stephanodscus invisitatus Hohn and Hellerman, studied by means of light, transmission, and scanning electron microscopy, shows a range of frustule diameters from 6.4 to 13.3 μ. Variation in valve ornamentation can be correlated with specimen diameter. The striae number ranges from 16 to 20 in 10 μ. Various processes difficult to observe by light microscopy alone are described which arise from the inside and outside of the frustules. ² 2 Note added in proof . The authors endorse the terminology of G. R. Hasle (1972, Beih. Nova Hedw., 39 :55–78.) in which the designation strutted tubulus has been employed for the structure referred herein as tube or tube-like process.
     

THE MORPHOLOGY AND FINE STRUCTURE OF CERATIUM HIRUNDINELLA (DINOPHYCEAE)1

Some aspects of thecal morphology in Ceratium hirundinella are redescribed by means of scanning electron microscopy. The internal anatomy of the cell has been clearly revealed for the first time in serial sections examined by transmission electron microscopy. An unusual sulcus, termed the sulcul aperture, has been found to open into a large ventral chamber which extends toward the center of the cell. The 2 flagella are inserted at one side of the ventral chamber. The ultrastructure of the flagellar canals and root systems arc described in detail. A microtubular strand has been found to run from near the nucleus to near the flagellar bases but not to conned with either. The fine structure of the theca, trichocysts, nucleus, and chloroplasts is basically similar to that of other dinoflagellates. Food vacuoles are reported. These contain material thought to be undergoing digestion. It is suggested that the food particles enter the cell by way of the ventral chamber, which is lined only by membranes, unlike the rest of the cell, which is covered by thick plates. The new findings are discussed in relation to the earlier work on the species and to the fine structure of oilier dinoflagellates.     

STRUCTURE,LIFE HISTORY AND SYSTEMATICS OF RHOICOSPHENIA (BACILLARIOPHYTA). I. THE VEGETATIVE CELL OF RH. CURVATA1

Rhoicosphenia Grun. has been placed by some authors in the monoraphid group with Achnanthes Bory and Cocconeis Ehrenb., and by others near Gomphonema Ehrenb. In order to clarify the systematic position of the genus, the morphology and anatomy of the vegetative cells of Rh. curvata (Kütz.) Grun. were investigated using light and electron microscopy. The structure and formation of the two types of valve are described, and the heterovalvy shown to be of a different type from that of the monoraphids; on the basis of raphe, valve and girdle structure a close relationship between these and Rhoicosphenia is unlikely. Rhoicosphenia shows many resemblances to Gomphonema but the types of pore occlusion present, coupled with apparently slight differences in the mucilage-secreting structures and the girdle, suggest that classification in the same family is unwise. The cryptic asymmetry of the valves, and in particular of the raphe system, is noted and explained with reference to their formation; with respect to this asymmetry two configurations of the valves can occur (named cis and trans types) and the distribution of these in raphid genera is discussed briefly. In view of the lack of evidence in raphid diatoms supporting a classification of bands into copulae and pleurae, it is recommended that this practice be suspended.     

VESSEL STRUCTURE OF GNETUM AND THE ORIGIN OF ANGIOSPERMS

Vessel structure of Gnetum gnemon L. and G. montanum Mgf. was investigated by means of light microscopy (brightfield, phase contrast and Nomarski interference optics), and scanning and transmission electron microscopy. The gyres of the first order framework are compound, consisting of three elementary strands (subunits). Pits ranging from slit-shaped to circular are formed either between the elementary strands of one gyre or between adjacent gyres. (Compound gyres are also figured for Alnus and lens-shaped pits in annular-helical elements are demonstrated for Juglans and Salix). In the two species of Gnetum studied, scalariform pits occur in addition to the well known circular pits. Scalariform perforation plates are present besides scalaroid, foraminate, and simple perforation plates as well as intermediates between the above types. These findings invalidate a common argument against the gnetalean origin of angiosperms, namely that pits and perforations of Gnetum are totally unlike those of primitive angiosperms and that therefore Gnetum must be ruled out as a potential ancestor of angiosperms. Variation in vessel structure of Gnetum is so great that it encompasses the typically circular pits of the coniferopsids as well as patterns of pits and perforation plates found in angiosperms. Some photographs of angiospermous taxa are interspersed with those of Gnetum to indicate the striking similarities. The determination of the patterns and shapes of pits and perforations is discussed in terms of four parameters: 1) the ratio of the width of the cell face to the distance between the gyres; 2) the types and distribution of the second order framework; 3) the stretching and distortion of gyres and/or second order framework; and in the case of perforations, 4) the pattern of wall and bar breakdown. Since the first parameter may change continuously, a continuum between circular pits or perforations and scalariform ones may occur. Such a continuum actually exists in Gnetum as well as in angiosperms. Patterns due to the other three of the above parameters are also formed in similar ways in both Gnetum and angiosperms. These similarities may, of course, be interpreted as the result of parallel evolution. However, when one considers the large number of angiospermous features of Gnetum, one is led to ask whether Gnetum may not have been close to the ancestral stock of all or at least some taxa of angiosperms.     

STRUCTURE AND REPRODUCTION OF THE ALGAL SYMBIONTS OF HYDRA VIRIDIS1

The algal symbionts of Hydra viridis are found within vacuoles of the gastrodermal digestive cells of the host. Electron microscopy reveals that the symbionts possess cell walls, and that their reproductive cycle follows the general pattern of free-living Chlorella. Nuclear and chloroplast divisions arc followed by formation of new cell walls, the Golgi apparatus being quite active during cell wall synthesis. Autospores are released when the parent wall ruptures. The autospores are then usually segregated into separate animal vacuoles. Remnants of the ruptured parent wall persist in the vacuoles for an indefinite period. The ruptured parent walls curl at the breakage clefts, forming double-layered scroll-like structures. The fate of these wall remnants has not been firmly established. Long-term starvation of the animals does not result in a detectable change in the structure of the symbionts, and they continue to divide and to store carbohydrate as starch grains.     

TAXONOMY AND FRUSTULAR STRUCTURE OF THE MARINE CENTRIC DIATOM PARALIA SULCATA1

Light and electron microscopy were used to investigate the complex structure of the frustule of Paralia sulcata (Ehrenb.) Cleve. Rimoportulae are reported for the first time in this diatom and two types of linking processes are described. The ease with which the cingulum is lost is explained with regard to its attachment to the valve. Two kinds of heterovalvy were observed and the taxonomic significance of one of these is discussed. The validity of Heiberg's genus Paralia is confirmed and a type slide of the species is designated.     

THE STRUCTURE AND FORMATION OF CILIA AND FILAMENTS IN RUMEN PROTOZOA

The large oligotrich rumen protozoa Diplodinium ecaudatum and Ophryoscolex caudatus have been studied by electron microscopy during interphase and division. The structure of mature cilia is contrasted with that seen during their formation particularly in a tuft where development lags and is arrested. Here the shaft is only a few micra long and is composed of filaments that have circular cross-sections not in the typical circular arrangement. In their diameter and appearance the filaments are similar to filaments associated with the nuclei during division. The macronucleus has within it randomly directed filaments, while the micronucleus contains well aligned filaments and other arrangements typical of an intranuclear mitotic process. An extranuclear filament system is also present and is elaborated during division. The infraciliary filament system is particularly elaborate in these organisms. Filaments ranging from 14 to 22 mµ have been observed with some tendency for a bimodal distribution in diameters of 15 and 21 mµ. Formation of such filaments has been observed and consists of an initial orientation of very fine elements followed by filament formation. The observations are discussed in relation to filament involvements in cell movements. The concepts are discussed that filaments are metastable structures and that the transitions from one state to another are functionally significant.     

ISOLATION AND CHARACTERIZATION OF GOLGI APPARATUS FROM EGGS OF FUCUS (PHAEOPHYCEAE)1

A golgi-rich cell-free fraction has been obtained from eggs of Fucus serratus L. and characterized by enzyme markers (IDP-ase and TPP-ase) and electron microscopy. The results are correlated with cytochemical localization of IDP-ase and TPP-ase in situ.     

BIOLUMINESCENCE AND OTHER CHARACTERISTICS OF COLLYBIA VELUTIPES

The growth in terms of linear extension and dry weight, endogenous respiration, bioluminescence and ATP concentration of Collybia velutipes has been considered. After an initial lag phase of approximately 4 days, linear growth extension with time is obtained. Dry weight measurements, however, indicate that secondary activity in previously formed cells occurs. One such activity is the formation of glycogen. The presence of glycogen, as determined by electron microscopy and several chemical tests, has been established in C. velutipes. Optimal endogenous respiratory activity occurs in tissue less than 48 hr of age, while maximal bioluminescent activity occurs in tissue that is 2–6 days in age. The maximum ATP concentration occurs in tissue approximately 7 days old.     

COLONY AND FRUSTULE MORPHOLOGY OF THREE TUBE-DWELLING DIATOMS FROM EASTERN CANADA1

Three species of Navicula are described from light and scanning electron microscopy. Navicula bottnica Grunow, has not previously been illustrated at the SEM level, nor has it previously been reported to form colonies, but the cells appear to be identical to Schizonema smithii C. Agardh (sensu van Heurck) and the name is amended to Navicula smithii (C. Ag.) van Heurck. The colonies are irregularly branched, the cells within forming strands which frequently appear braided. Material of N. delognei van Heurck differs in several points from typical material and a new form, elliptica is proposed. Observations on the third species, N. pseudocomoides corroborate recent work by Cox in Britain.     

SPORE MORPHOLOGY OF ANEMIA,MOHRIA, AND CERATOPTERIS (FILICALES)

Spores of the ferns Anemia and Mohria (Schizaeaceae) and Ceratopteris (Pteridaceae) are surveyed with light microscopy and scanning and transmission electron microscopy. In each genus the spores are trilete with radially symmetrical exine sculpture comprising three sets of parallel or near-parallel muri. Anemia has six spore types. One is reticulate (A. wrightii-type), and the other five types have either cicatricose or canaliculate sculpture that reflect a basic form, i.e., three mural sets that have mutual anastomoses in each radial region. The cicatricose A. mexicana- and the canaliculate A. dregeana-types represent the simplest expressions of this pattern. Specializations include cicatricose, auriculate (A. raddiana-type) and canaliculate, ornate (A. oblongifolia-, A. phyllitidis-types). Exine structure is homogeneous or differentially microporate; the enveloping two-layered perine has granulate structure and a granulate to spiculate and/or pitted surface. Mohria spores have a stratified, granulate to rugulose perine and cicatricose exine sculpturing consistent with the A. mexicana-type pattern, but the muri are hollow. The canaliculate spores of Ceratopteris differ from those of Anemia and Mohria in that the three mural sets are discrete and separated from each other by a stria in each radial region; exine structure is homogeneous and the thin perine is granulate. Within Anemia the A. raddiana-type is exclusive to subgen. Coptophyllum and the A. oblongifolia- and A. phyllitidis-types to subgen. Anemia. Three spore types are shared by two subgenera; i.e., A. wrightii- and A. mexicana-types in Coptophyllum and Anemirhiza, and the A. dregeana-type in Anemirhiza and Anemia. Spore polymorphism is indicated in several species of subgen. Anemia, and smooth immature spores are recorded from all three subgenera.     

COMPARATIVE MORPHOLOGY AND PHYLOGENY OF THE RANALES

Comparative morphological studies of woody Ranales have established the primitive status of the group and hence their key place in angiosperm phylogeny. Significant advances in our knowledge of some ranalian families have been made in recent years. An attempt is made in the present review to bring together a range of morphological data (vegetative and floral anatomy, palynology and embryology) on the Ranales (sensu lato), with particular reference to research work published after the publication of Eames's (1961) book, and to discuss the relationships of the families. Recent ontogenetic studies have shown that the carpel of Drimys is ascidial and not conduplicate as earlier suggested. The inclusion of Degeneria in the Winteraceae is not supported by morphological data. Melville's gonophyll theory has been shown to be inapplicable to the magnoliaceous flower. The pollen of Schisandra is interpreted as derived and specialized rather than primitive as previously supposed. The removal of Schisandra from Magnoliaceae is upheld by morphological evidence. Recent morphological studies do not support a close relationship between Schisandraceae and Illiciaceae suggested by earlier authors. The Canellaceae shows similarities to Winteraceae, Magnoliaceae, Illiciaceae, Eupteleaceae and Myristicaceae. Transitional types of division of pollen mother cells found in Winteraceae, Schisandraceae and Annonaceae and their probable phylogenetic significance have been discussed. The Annonaceae, Winteraceae, Degeneriaceae, Magnoliaceae, Schisandraceae and Cercidiphyllaceae share several embryological features in addition to similarities in floral structure. Ruminate endosperm is regarded either as an archaic feature retained in some taxa or as a later and parallel development in others. Thus its value in assessing relationships seems to be doubtful. Myristicaceae has been shown to be closely related neither to the the Annonaceae nor to the Lauraceae. The suggested relationship of Eupomatiaceae to Annonaceae is not supported by palynology. Floral cortical vascular systems in Magnoliaceae, Annonaceae, Calycanthaceae and Myristicaceae have been compared and it is concluded that they may be vestigial structures. A great deal of similarity has been found between Lauraceae and Calycanthaceae in wood, node, flower structure and embryology. Further floral anatomical evidence has been adduced to support the removal of Scyphostegia from Monimiaceae. The Hernandiaceae show similarities to some members of Monimiaceae while the Gyrocarpaceae resemble the Lauraceae, Gomortegaceae and certain other genera of Monimiaceae. Available evidence from wood and floral anatomy and embryology indicates close relationships among Lauraceae, Monimiaceae and Hernandiaceae. Vegetative and floral anatomical and embryological data seem to indicate a place for the Chloranthaceae in the ranalian complex. Recent anatomical studies in the Nymphaeaceae show that the floral structure is of a primitive type with similarities to the woody Ranales. Available morphological evidence is considered inadequate to express an opinion on the splitting of the family. Ceratophyllaceae is regarded as a highly reduced ranalian family derived most probably from a nymphaeaceous stock. The gynoecium in Berberidaceae is interpreted as monocarpellate. No evidence has been found to support the tricarpellate view. Berberidaceae, Lardizabalaceae and Menispermaceae share several embryological features, while at the same time showing evidence of specialization, each in its own way. Thus they might have arisen from a common stock and early diverged along different lines. The occurrence of several types of embryo sac in Ranunculaceae may well be an indication of specialization, but their probable taxonomic value, if any, is not yet clear. The occurrence of numerous primitive features in Paeonia has been suggested as an argument for its retention in the Ranales. No evidence has been found to preclude the inclusion of Dilleniaceae in the Ranales. On the other hand, as opposed to similarities in wood and pollen characters between Dilleniaceae and Theaceae, floral anatomical and embryological features offer a sharp contrast between the two. The Ranales are believed to be polyphyletic. It has been tentatively suggested that two major phyletic lines may be recognized in each of the woody and herbaceous series: the magnolialian and lauralian lines in the former and the nymphaealian and berberidalian lines in the latter.     

OBSERVATIONS ON THE CHARACTERISTICS OF THE LEMMA AND PALEA OF THE LATE CENOZOIC GRASS PANICUM ELEGANS

Scanning electron microscopy (SEM) was used to study the surface features of the anthoecia (fertile lemma and palea) of Panicum elegans Elias from the Late Cenozoic deposits in Ellis County, Kansas. Examination of the lemma revealed a well developed germination lid, irregularly arranged, simple, rounded papillae and a crescent-shaped scar of attachment. The presence of a germination lid indicates that this structure has been present in some members of the Gramineae since at least the Late Miocene-Early Pliocene. Evidence is presented which contradicts current ideas regarding the distribution of the germination lid in extant Gramineae. The surface of the palea is characterized by simple, rounded papillae spaced in regular rows. The arrangement and form of these papillae are like that present in some modern Dichanthelium. Both the epidermises of the lemma and palea are composed entirely of long cells with strongly sinuous, interlocking cell walls. The pattern of cells on the lemma indicates that the systematic placement of Panicum elegans is correct.     

POLLEN MORPHOLOGY,TRICHOME TYPES,AND RELATIONSHIPS OF THE GRONOVIOIDEAE (LOASACEAE)

The pollen of all four genera of Gronovioideae—Cevallia, Fuertesia, Gronovia, and Petalonyx—was examined in light microscopy, and scanning and transmission electron microscopy. The pollen of Cevallia, of Fuertesia, and of Gronovia can be easily distinguished from each other and from all remaining Loasaceae. Only Petalonyx, with a striate tectum, shows a clear relationship to the Mentzelioideae and Loasoideae, the vast majority of which have striate-reticulate or striate tecta. The trichome data are mostly congruent with the pollen data: Cevallia, Fuertesia, and Gronovia each have a distinctive trichome not known to occur elsewhere in the family, while Petalonyx has only the common types. A cladistic analysis of Gronovioideae utilizing Mentzelia as the outgroup proposes that Cevallia, Gronovia, and Fuertesia are a sister group to Petalonyx within the subfamily. The relationships of the four genera to each other and of Gronovioideae to the Loasaceae are discussed.     

ELECTRON MICROSCOPIC AND HISTOCHEMICAL COMPARISON OF THE TWO TYPES OF ELECTROPLAQUES OF NARCINE BRASILIENSIS

The torpedine electric fish Narcine brasiliensis has two morphologically distinct electric organs (main and accessory) which also differ with respect to a number of electrophysiological properties. The fine structure of the electroplaques of these organs has been examined by electron microscopy and by a histochemical method for localizing esterase activity with a high degree of resolution. In both kinds of electroplaques the innervated surface (ventral in those of the main organ, dorsal in those of the accessory) is the only site of esterase activity. The latter is further confined to the regions of synaptic contact between vesicle-containing axon terminals and the electroplaque membrane. The synaptic apparatus is similar to, but less elaborate than, that of neuromuscular junctions. The axon terminals and electroplaque membranes are free of connective tissue envelopments. The membrane of the uninnervated surfaces forms a continuum with a dense canalicular network which penetrates deeply into the 7 µ thick electroplaques of the main organ. The canalicular network has about the same thickness in the 20 µ electroplaques of the accessory organ. Except for this difference, the two kinds of cells appear to have the same fine structure. This finding is discussed in relation to the electrophysiological data on functional differences.     

THE EVOLUTION AND SYSTEMATICS OF BEE-EATERS (MEROPIDAE)

Behavioural and ecological characters are used in addition to structural ones in considering the systematics of the Meropidae. The two species of Nyctyornis are the most primitive extant forms. Meropogon is retained as a monotypic genus for forsteni, and all other bee-eaters are placed in the single genus Merops, being ecologically and morphologically rather uniform except in details of wing and tail structure, which should be considered only of specific importance. M. breweri and M. oreobates are thought to be secondarily rather than primarily forest species. With the submergence of Aerops and Melittophagus, and the monotypic genera Bombylonax and Dicrocercus, which are considered to be closely related to the pusillus species-group, Merops is enlarged to 21 species which are uniform except in tail-shape, wing formula and throat feather structure. These characters are of specific importance only, and have a mosaic distribution within the genus. Their use in the definition of the formerly recognized genera results in an artificial classification. The proposed delimitation of species-groups within Merops differs somewhat from previous arrangements, and affinities argued in the text are summarized in Fig. 15, which shows superspecies and species-groups. The species recognized are formally tabulated below. The Meropidae probably originated in southeast Asian forest and spread through former forest to Africa. Only in Africa was the open-country environment invaded, and speciation in the savanna was in two main directions, producing small sedentary and large migratory species. Representatives of both types returned to Asia in open country. From the present distribution of species it is inferred that speciation has proceeded under the main influences of (1) isolation of a population and its habitat in Pleistocene Africa and (2) isolation of migrants away from their breeding range. The distributions of species with wide or rather limited ranges are discussed in terms of physiological adaptation and ecological competition. Opinion has not been expressed on the validity of subspecies, which have been discussed only in delimiting controversial species. In the following summary, the only subspecies named are those affected by changes from Peters' scheme (cf. Table 1). Superspecies are bracketed. Nyctyornis amicta N. athertoni Meropogon forsteni Merops guloris M. mülleri M. bulocki M. bullockoides M. pusillus M. variegatus (?loringi, oariegatus, lafresnayii, bangweoloensis) M. oreobates M. hirundineus M. breweri M. revoilii M. albicollis M. orientalis M. boehmi M. viridis M. superciliosus (persicus, chrysocercus, superciliosus) M. philippinus (philippinus, salvadorii) M. ornatus M. apiaster M. leschenaulti M. malimbicus M. nubicus (nubicus, nubicoides)     

ASSOCIATION OF THE ENDOPLASMIC RETICULUM AND THE PLASTIDS IN ACER AND PINUS

A close sheathing of the plastids by endoplasmic reticulum has been observed. This is restricted to the companion cells and developing sieve tubes of the phloem of Acer pseudoplatanus and the resin canal cells and leaf callus cells from Pinus pinea. The sheathing is transitory in callus and sieve tubes but is a permanent feature of the companion and the resin canal cells. Possible functional relationships between the two organelles are discussed.     

FINE STRUCTURE IN RELATION TO FUNCTION IN THE EXCRETORY SYSTEM OF TWO SPECIES OF VIVIPARUS

The fine structure of the excretory system of 2 species of Viviparushas been studied by scanning and transmission electron microscopy.The structure of the heart is described and its mode of operationdiscussed. The structure and function of the kidney and ureterare discussed and it is concluded that the nephridial glandhas hypertrophied (Received 30 October 1978;     

THE STRUCTURE AND REPRODUCTION OF GLAPHYRYMENIA PUSTULOSA

Norris , R. E. (U. Minnesota, Minneapolis.) The structure and reproduction of Glaphyrymenia pustulosa. Amer. Jour. Bot. 48(3): 262–268. Illus. 1961.—Specimens of Glaphyrymenia pustulosa, a red alga from Australia that has seldom been found, were collected recently. The specimens were examined particularly with respect to development of the vegetative tissues and the formation of the female reproductive apparatus and gonimoblast. The vegetative structure is primitive in the Kallymeniaceae and structural characteristics are present that are similar to the Cryptonemiaceae and Dumontiaceae. The female reproductive system has a monocarpogonial carpogonial branch apparatus and an auxiliary cell that is borne on a separate system that does not have a carpogonial branch. After fertilization, stages in the development of the gonimoblast are similar to those of Kallymenia and Pugelia.