SPIRAL DEVELOPMENTAL PATTERNS IN THE STEM AND INFLORESCENCE OF LILIUM TIGRINUM

Extensive correlations in spirality were observed among vegetative and floral organs in Lilium tigrinum Ker. Organs involved were vegetative leaves, bracts, and bracteoles. These correlations varied in their degree of constancy depending upon the organs involved. The mature inflorescences of L. tigrinum appeared to fit the common definition of a raceme. In 67.3% of the flowers at node 3 on the raceme, the bract-bracteole spirals reversed the spiral of vegetative leaves on the stem. These reversals resembled those observed on essentially cymose inflorescences of certain members of the Caryophyllaceae. Cymose branching was found to be an invariable feature of the inflorescence of L. tigrinum when secondary flowers appear. The apparently indeterminate tips of inflorescence main axes were interpreted as exhibiting stages in progression from a basically determinate (cymose) inflorescence. It was concluded that the ancestors of L. tigrinum had well-developed cymose branching patterns in the inflorescence. Reversal of stem spirals by the bract-bracteole spirals at the apices of many inflorescences was considered to be the result of complete utilization of the inflorescence meristem. Explanations for those reversals were provided by the field theory and by the theory of the first available space.     

PATTERNS OF STEM VASCULATURE IN PHILODENDRON

A survey of 480 collections of stem material of Philodendron has established five patterns of vascular organization. Species representing each of these patterns were analyzed by cinematographic methods to allow a three-dimensional interpretation of the course of vascular bundles over extended distances. Pattern 1 has mainly collateral organization, but with some bipolar bundles. Pattern 2 has a majority of central bundles aggregated into compound (multipolar) bundles; Pattern 3 differs in that almost all bundles of the central cylinder are multipolar. Patterns 4 and 5 include compound vascular bundles in which the individual strands are not very discrete so that in Pattern 5, which is the most common in the genus, the bundles might be described as amphivasal. In Section Pteromischum, which has monopodial construction, the majority of species exhibit Pattern 2 which is exclusive to this group. Other correlations with subgeneric groupings are emphasized.     

DEVELOPMENTAL ANATOMY IN ROOTS OF IPOMOEA PURPUREA. I. RADICLE AND PRIMARY ROOT

The developmental anatomy of the primary root of Ipomoea purpurea was studied at several growth stages, beginning with the radicle. The radicle is generally composed of three superimposed tiers of initials, which produce the vascular cylinder, cortex, and columella; and a peripheral band of lateral rootcap-epidermal initials. The radicular cortex contains 16–19 immature laticifers; none of the tissue regions in the radicle contains mature cells. Following germination and during the first 2–3 cm growth of the primary root the apical meristem and its derivative tissues undergo a series of modifications. Root apical diameter decreases as cells in lateral portions of the rootcap elongate; meanwhile, the columella enlarges vertically. The relationship between cortical and columellar initials changes as fewer mitoses occur in the former while the latter remain active. In longer roots the columellar initials are directly in contact with the vascular initials. Cortical size diminishes during early root growth as cortical laticifers and their associated cells cease to be produced by the outer cortical initials and ground meristem. Early procambium, at the level of vascular pattern initiation, decreases in diameter by cellular reorientation, and the vascular cylinder decreases in overall diameter although the tetrarch pattern remains unchanged.     

PATTERNS OF REPRODUCTION IN FOUR LITTORINA SPECIES

The reproductive periodicities of four Iittorinids, Littorinaneglecta, L. nigrolineata, L. saxatilis and L. arcana were examinedin sympatric populations at Porth Swtan, Anglesey, North Wales.Three species, L. neglecta, L. nigrolineata and L. arcana, werefound to show marked reproductive periodicity. L. saxatilisshowed no periodicity and large numbers of animals were foundin breeding condition throughout the year. The oviparous speciesL. nigrolineata and L. arcana, came into reproductive conditionin the late summer or early autumn, L. nigrolineata in Augustand L. arcana in September, and their populations at Porth Swtanhad few individuals in breeding condition in the late springand early summer. L. neglecta, however, showed a periodicitywith high numbers of breeding animals throughout the springand summer and very low numbers in the autumn. For L. neglectathe basis of reproductive periodicity is shown to be the synchronizedannual life cycle of individuals of this species. It is thereforebelieved to differ from the other three species in which individualsare longer-lived and are supposed to undergo seasonal periodsof reproductive inactivity. (Received 2 March 1982;     

PATTERNS IN THE GEOGRAPHICAL RANGES OF SPECIES

1. A growing number of studies have documented patterns in species geographic ranges relevant to the study of community structure. These include patterns in the frequency of geographic ranges of different sizes, and in the interaction of range sizes with population abundances and variabilities, body sizes, trophic characteristics and extinction probabilities.
2. Agreement between hypothesized and observed relationships is reasonably good, but we do not know how general the patterns are. Analysis of patterns has focused upon a few taxonomic groups, a bias largely resulting from a lack of information on the geographic distributions of most taxa.
3. Many of the patterns are interrelated, and although theoretical bases to all the patterns can be suggested, it is possible that some are artifacts.
4. Taylor power plots give us a means of making predictions about population behaviour as it pertains to geographic ranges. Some of these predictions suggest that previous conceptions of such interactions have been too narrow, but empirical analyses of these patterns will be hampered by the difficulty of measuring population variability.
5. In general, our knowledge of the structure, and spatial and temporal behaviour, of species geographic ranges remains poor.     

PATTERNS OF MACROALGAL SPECIES DIVERSITY IN DANISH ESTUARIES

We analyzed species number of macroalgae in relation to environmental variables at two spatial levels comprising 202 individual sites and 26 entire estuaries in Denmark. The species number of macroalgae increased with salinity and declined with nutrient concentrations both at the sites and in the estuaries. Availability of hard substratum was associated with higher species richness at the sites. The number of macroalgal species in the estuaries increased with higher mean depth and longer coastline, suggesting that both the vertical and horizontal extension of the colonization area are important for the maximum representation of macroalgal species. Mean depth explained as a single predictor 60% of the variability in species number in entire estuaries. Estuaries with high mean depth also tend to be large and have high salinity and transparent waters due to efficient exchange with open waters. In conclusion, we find that the regulation of species richness of macroalgae in Danish estuaries, though complex, is influenced predictably by salinity, water transparency, nutrient concentration, and availability of hard substrata.     

SURVIVORSHIP PATTERNS IN THREE SPECIES OF CAPTIVE CETACEANS

Survival rates for three species of captive cetaceans are reported, based on records of dates of capture, birth, and death of individual animals. The annual survival rate was 0.93 for bottlenose dolphins and killer whales and 0.94 for white whales. Confidence limits of these estimates are discussed. Differences in survival rates between institutions were significant for bottlenose dolphins only. Calf survival for bottlenose dolphins was lower than non-calf survival. Survivorship of male killer whales was significantly less than survivorship of female killer whales; sex-specific survival rates were similar for the other two species. Estimates of average or maximum longevity alone were not useful in comparing rates of survival. Because survival in the first year of captivity may be lower than subsequent years, estimates of the expected lifespan, based on data from the first few years of captivity, may be biased.     

PATTERNS OF GENOTYPIC DIVERSITY IN CLONAL PLANT SPECIES

We compile and analyze data on the population genetic structure of broad-sense clonal plant populations where sexual recruitment is rare or absent. The data from 27 studies show a common theme: multiclonal populations of intermediate diversity and evenness tend to be the rule, most clones are restricted to one or a few populations, and widespread clones are exceptional. While a few studies have demonstrated that ecological differences among sympatric clones do occur, more experimental and theoretical studies are necessary to determine the role of selection and other evolutionary forces in maintaining clonal polymorphism.     

DEVELOPMENTAL STUDY OF BRANCHED RHIZOPHORES IN THREE SELAGINELLA SPECIES

A morphogenetic investigation was made of the rhizophore of three large-sized tropical Selaginella species. The rhizophores of Selaginella delicatula, S. caudata, and S. plana arise exogenously at the points of branching of the main stems. In S. delicatula they are initiated at the junction of the second youngest branching. The rhizophore apical meristem has a tetrahedral apical cell and is capless. The rhizophores are usually three or four times dichotomously branched in S. delicatula and S. plana and four or five times in S. caudata. In S. delicatula, dichotomous branching of the rhizophore involves formation of two new apical cells subsequent to loss of an original apical cell. A pair of roots is formed endogenously from inner cells below the dermal layer at the apex of ultimate rhizophore branches. The finding that the rhizophore is an autonomously branched, leafless, and capless axis leads us to argue that Selaginella rhizophores, like lepidodendrid rhizomorphs, are fundamental axial organs that coordinate with the stem and root.     

X-CHROMOSOME INACTIVATION AND DEVELOPMENTAL PATTERNS IN MAMMALS

1. The review considers information from mammalian embryology relevant to X-chromosome inactivation, and from X-inactivation relevant to mammalian embryology. 2. Properties of the inactive-X, by which it may be recognized are: sex chromatin, heteropycnosis, late replication and the absence of gene product. Each of these has advantages and disadvantages in particular circumstances. In some species the X carries constitutive heterochromatin, which must be distinguished from the facultative region. 3. The time of X-chromosome inactivation can be estimated from the time of appearance of sex chromatin or late replication, or inferred from the appearance of heterozygotes for X-linked genes or of experimental chimaeras. The estimated time varies with species, and in the mouse and rabbit is near the time of increase in RNA synthesis. 4. Whereas in eutherian mammals either the maternally or the paternally derived X may be inactivated in different cell lines, in marsupials the paternal X is always the inactive one. 5. During development various factors act to distort the patterns produced by random X-inactivation. These factors include cell selection, transfer of gene product, and migration and mingling of cells. 6. There is no clear evidence that X-chromosome inactivation is not complete. 7. In female germ cells both X-chromosomes appear to be active. In male ones both X and Y appear inactive during most of spermatogenesis, although probably in early stages all X chromosomes present are active. 8. The active and inactive X-chromosomes may be differentiated by presence or absence of some non-histone protein or other polyanionic substance. 9. If the genes concerned in synthesis or attachment of this substance are on the X-chromosome then the differentiation will be self-maintaining. 10. The initiation of the differentiation requires either the attachment of different X-chromosomes to different sites, or some interaction of X-linked and autosomal genes, concerned in inducing or repressing activity. Some possible models are discussed.     

DEVELOPMENTAL PATTERNS OF GANGLIOSIDES AND OF PHOSPHOLIPIDS IN CHICK RETINA AND BRAIN

Abstract— The changes in phospholipids and gangliosides during ontogenesis of chick retina have been compared with those in brain. Three phases of accumulation of ganglioside NeuNAc in the retina were detected. In contrast, brain NeuNAc rapidly increased during embryonic life until hatching, followed by a slower increase up to the adult stage. The phospholipid changes in retina and in brain occur in a-similar manner to the variations observed for gangliosides, however in retina the changes of phospholipid content are less marked than in brain, during embryonic life. There were marked changes in the retina and brain ganglioside patterns with age. G _{d 3} and G _{d 1b} decreased rapidly in per cent; correspondingly, G _{d 1a} increased during embryonic life and became the major ganglioside in place of G _{d 3}. There was a similarity between ganglioside patterns of chick retina and brain. Except for some slight variations during embryonic life, the retinal phospholipid pattern did not change noticeably.     

爬树龙的组织培养

爬树龙(Rhaphidophora decursiva (Roxb.)Schott),别名过山龙,系天南星科(Araceae)崖角藤属(Rhaphidophora)的一种藤本植物,以气根攀缘于它物上生长,叶表面绿色、发亮,它不仅是一种多年生常绿的观赏植物,而且其茎叶入药,可医治许多病症,因此有一定的药用价值。通常用扦插方法繁殖,我们取它的茎尖和茎节进行组织培养试验,现将初步试验结果简要报道如下。     

ASEXUAL DEVELOPMENTAL PATTERNS OF THE DIATOM STAURONEIS ANCEPS IN CULTURE123

During several months under controlled growth conditions, cell division in the diatom Stauroneis anceps resulted in a gradual decrease in length as predicted by the Macdonald-Pfitzer hypothesis. Cells of a clone decreased in average length from 35 to 17 μ. The smallest cell observed measured 12 μ. Cells longer than 26 μ typically had capitate ends. As the cells became shorter, there was a gradual decrease in this capitate configuration with the smallest cells being oval in outline. The estimated increment of size reduction due to cell division in the clone was 0.1 μ per division. This value is dependent on the assumption of random division. Populations with cells less than 28 μ in length showed an increase in valve aberrations, but these cells continued to reproduce. A cell 13 μ long and similar to the smallest specimen of the clone was observed from a core sample with fossil specimens of S. anceps.     

PRIMARY XYLEM ELEMENTS AND ELEMENT ASSOCIATIONS OF ANGIOSPERMS

Observations based on a study of more than 1350 species distributed among 165 families of angiosperms are presented. The tracheary elements which mature later than the helical ones in the protoxylem-metaxylem transition are described in terms of a 2-phase wall deposition process. These elements have a helical framework (first-order secondary wall) between the gyres of which is deposited additional secondary wall material in the form of sheets or strands or both (second-order framework). This is indicated both by the sequence of mature elements throughout the primary xylem and by the ontogeny of later maturing elements. Elements in which the second-order system of the secondary wall is deposited more or less synchronously and in which the sheets or strands are restricted to cell edges, i.e., lines of intersection of adjacent cell faces, are interpreted as primitive. Elements in which the second-order sheets and strands appear nonsynchronously and with less regard for cell edges are interpreted as advanced. Alternate pitting results from the appearance of oblique second-order strands with subsequent wall deposition maintaining strand orientation such that pit axes are tilted. In certain elements second-order strands are deposited before, and wall deposition continues after, the cessation of cell elongation. This results in an alternate pit pattern and may explain certain irregular patterns. Branching of the first-order helix seems to be relatively insignificant in the development of more elaborate wall patterns. It is more significant in perforation plate elaboration. “Open pits” occur in a number of dicotyledons. These are pit-like openings which are extended laterally as the thin areas between the gyres of a helix or comparable openings in a reticulum. They constitute a conspicuous feature of the entire protoxylem-metaxylem transition in certain species. The simple perforation plate of only certain angiosperms seems to be the result of bar breakdown in a multipored plate. Reduction in pore number is also the result of fusions in the first-order framework lateral to a multipored plate. In dicots this trend rarely culminates in a simple perforation plate, but it frequently does so in monocots. This type of pore number reduction and enlargement frequently accompanies bar breakdown in dicots and certain monocots. The perforation plate is often simple as the result of a terminalization on the cell, in which case the pore does not intersect the first-order framework. This type of perforation plate occurs in species with and without more obliquely oriented simple perforation plates subject to a breakdown interpretation. Complex multiperforate plates are interpreted as falling into 3 categories : Plates in which a reticulum has resulted from introduction of second-order secondary wall strands at various orientations and with variable amounts of distortion following deposition; plates in which a reticulum has resulted from ramification and fusion of the strands of the first-order framework ; and plates which are multiperforate as the result of the presence of a number of separate loci of breakdown within a single pore membrane. Possible ontogenetic complexities in the development of perforation plates subject to breakdown interpretation are discussed. Protoxylem-metaxylem transitions are described in terms of the sequence of types of perforation plates. Most sequences with various types of plates support the concept of progressively earlier ontogenetic expression of specialized features with progressive elimination of primitive ones. The concept is contradicted by those species in which nearly all perforation plates are simple. Non-simple plates in these species are found from early protoxylem through mid-metaxylem but not in the earliest protoxylem. If non-simple plates are uncommon in a species, they may have a different ontogenetic history in terms of procambial divisions and apical cell growth. In the monocots with a variety of perforation plate types, the probability that a given element will be imperforate or perforate in one way or another will depend on its diameter, not on its position within the sequence. The occurrence of vessels of very limited extent is discussed. It has been calculated that vessels in the stem of Scleria average from 2 to nearly 50 cells in length depending on their diameter.     

FLORAL PIGMENTATION STUDIES IN THE GENUS GOSSYPIUM. I. SPECIES SPECIFIC PIGMENTATION PATTERNS

Previous work on cotton flower pigments is outlined. The major flavonoids are glycosides of gossypetin, quercetin, and kampferol. Twelve flavonol glycosides have been tentatively isolated and identified, while a number of minor components remain unidentified. The gossypetin glycosides are gossypin, gossypitrin and a C₇-linked glycoside of unknown sugar residue. The quercetin glycosides include isoquercitrin, rutin, a third C₃-linked glycoside with unknown sugar residue, quercimeritrin and a second C₇-linked glycoside with sugar residue unknown. The kampferol glycosides include trifolin, kampferol rutinoside and 2 other C₃-linked glycosides with unknown sugar residues. The major anthocyanin throughout the genus is cyanidin. Mutants which affect visible flower color were studied in 3 species (G. arboreum, G. hirsutum, and G. barbadense). The majority of these mutants act to decrease or prevent the synthesis of gossypetin glycosides. The only exceptions to this are the mutants at the Y_a locus in G. arboreum, which affect all of the C₇-linked glycosides in one case, and in the other reduce over-all flavonol production. In all instances, the species could be positively identified by the residual array of pigments not affected by the mutant alleles concerned; i.e., visual similarity of phenotypes did not obscure the basic pattern of pigmentation characteristic of the different species.