摘要:

SUMMARYComparative 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 ofDrimysis ascidial and not conduplicate as earlier suggested. The inclusion ofDegeneriain the Winteraceae is not supported by morphological data.Melville's gonophyll theory has been shown to be inapplicable to the magnoliaceous flower.The pollen ofSchisandrais interpreted as derived and specialized rather than primitive as previously supposed. The removal ofSchisandrafrom 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 ofScyphostegiafrom 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 inPaeoniahas 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.

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01213.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary1The synthetic insecticides have been used in steadily increasing quantities since the Second World War and are non‐specific poisons, and so pose the possibility of sublethal effects on wild populations of animals.2The organochlorine insecticides in general, and some of the cyclodienes in particular, are usually much more persistent than the organophosphorus and carbamate insecticides, both in the environment and within individual insects.3Analyses of samples suggest that traces of the organochlorines are widely dispersed over the entire globe.4Although the evidence is incomplete, all of these synthetic insecticides appear to exert their primary toxic lesion by interference with the conduction of impulses in the nervous system.5The complete pattern of events that ends in death includes the release of secondary toxins into the blood. These are probably physiologically active compounds, normally present, but liberated in excessive amounts by excessive nervous stimulation.6A condition similar to the late, paralytic, stage of insecticidal poisoning can also be produced, inPeriplaneta americana,by excessive physical stimulation and there are similarities in the physiological changes caused by both types of stimuli. This suggests that a generalized stress syndrome develops after excessive nervous stimulation. However, this similarity has so far only been demonstrated for this one insect species.7Sublethal effects have so far only been looked for cursorily. Interpretation of sublethal effects is sometimes difficult; apparent differences between dosed and control individuals may sometimes be caused by selective mortality of the dosed individuals. Four main types of effect have been found.8Latent toxicity, which is evident as a reduction of longevity or of death at particular developmental stages, has been found only with organochlorines, appears to be linked with fat metabolism, and shows clearly that sublethal effects may be produced a long time after acquiring a dose of a persistent insecticide.9All types of synthetic insecticide can affect reproductive potential, and may increase or decrease the number of eggs produced. Egg fertility or development of offspring may also be affected. Reductions are sometimes caused directly by inhibition or distortion of ovary development, sometimes indirectly by reduced feeding.10The few studies on behaviour have shown that activity may increase, feeding decrease, and the acceptance threshold of sucrose be lowered.11DDT induces the formation of more detoxifying microsomal enzyme inTriatoma infestans.12I suggest that latent toxicity and some behavioural changes are probably caused by direct effects on the nervous system, but that some of the other results may be secondary effects associated with the stress syndrome. There is also the possibility of direct insecticidal action on other systems.It is a pleasure to thank our librarian, Mrs Jean King, for her unfailing help in tracing reference

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01214.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01215.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

SUMMARY1Biological nitrification is mediated primarily by two genera of bacteria,Nitrosomonasand its marine formNitrosocystis,oxidizing ammonia to nitrite, andNitrobacter,converting nitrite into nitrate. These are chemoautotrophic organisms since they usually derive their energy for growth by oxidizing these inorganic nitrogen compounds and their carbon from carbon dioxide, carbonates or bicarbonates.2The morphology and structure of these Gram‐negative bacteria studied by electron microscopy show numerous intracellular membranes reminiscent of those in photosynthetic bacteria and blue‐green algae. These structures may therefore be associated with the production of ATP.3The bacteria are difficult to grow in pure cultures in sufficient amounts for biochemical work since their generation time is around 10 hr. and the yields are only about one hundredth of those obtained with heterotrophic bacteria. Thus in continuous cultures great care must be taken to avoid ‘wash‐out’ of the cells. SinceNitrosomonasandNitrosocystisproduce copious amounts of nitrous acid, which would eventually retard growth, pH stat units are used to titrate the cultures continuously with a solution of sodium carbonate, to hold the pH around 7–8.4The respiratory chain which is associated with cell membranes, contains flavin, quinones and many cytochromes linking to oxygen as a terminal acceptor. InNitro‐somonas‐Nitrosocytishydroxylamine is oxidized by the electron transfer chain and inNitrobacternitrous acid is utilized. The ammonia‐oxidizing system, which inNitrosomonasprobably resides near the cell surface, does not appear to survive cell breakage. During the oxidation of hydroxylamine and nitrous acid by the respiratory chains, a phosphorylation occurs but the P/O ratios around 0–30 are low. There is little energy reserve material in the cells, possibly β‐hydroxybutyrate and some metaphosphates and as soon as the oxidative processes are impaired the cells cease dividing.5Chemoautotrophic bacteria have a novel way of producing reduced nicotinamide adenine dinucleotide (NADH). This involves a reversal of electron flow from reduced cytochromecto nicotinamide adenine dinucleotide (NAD) that is energy‐dependent, thus requiring adenosine triphosphate.6Reductase enzymes, nitrate, nitrite and hydroxylamine reductases inNitrobacterand nitrite and hydroxylamine reductases inNitrosomonas,have been described. They appear to be readily extracted in soluble form and are probably assimilatory enzymes since16N labelled nitrate, nitrite and hydroxylamine respectively inNitrobacterand the last two inNitrosomonasare readily incorporated into cell nitrogen. It has been suggested that a particulate nitrate reductase inNitrobacteris coupled to the synthesis of adenosine triphosphate but adequate experimental evidence for this concept has not been produced.7Some recent observations withNitrobactersuggest that it grows on acetate, deriving all its energy and carbon skeletons from this source but the mean generation time for the bacterium is unchanged. Under these conditions the carbon dioxide fixing enzymes of the pentose pathway are suppressed. This then is a case offacultative chemoautotrophybut there is no increase in the biosynthesis of the TCA enzymes. Whether this is a widespread phenomenon in other chemoautotrophic bacteria remains to be established. If this does prove to be the case it would aid their survival in a variety of habitats and extend their distribution in soils and seas.8The carbon dioxide fixing enzymes of the pentose pathway are found in the soluble parts of the cells. The major route is via the carboxydismutase system with only a small incorporation via the phosphoenolpyruvate carboxylase enzyme. Enzymes of the tricarboxylic acid cycle have low activities compared with those in heterotrophs and this overall slow metabolism, rather than the lack of a specific enzyme such as NADH oxidase, may well account for the slow growth of these bacteria. Although there is very active glutamic dehydrogenase inNitrosomonasthat utilizes ammonia, the enzyme has a very small activity inNitrobacter.This poses a problem of the route of incorporation of nitrite nitrogen into cell nitrogen in the latter bacterium.9A few heterotrophic fungi have been described which oxidize ammonia to nitrate but their activity is small compared with that of the nitrifying bacteria.10It is concluded that the nitrifying bacteria which have many novel biochemical features not met with in other organ

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01216.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01217.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

SUMMARYThe fossil records of the four living reptilian orders can be traced into the Triassic. The earlier ancestry of the turtles has not been established. Squamates and rhyncho‐cephalians evolved from the Late Permian eosuchians; crocodiles from the thecodonts. The ancestry of the eosuchians and thecodonts is to be found in the central stock of Permo‐Carboniferous reptiles, the captorhinomorphs. The earliest captorhino‐morphs, from the Lower Pennsylvanian, are already fully developed reptiles. The limnoscelids and solenodonsaurids are more primitive forms, retaining features typical of anthracosaurian amphibians.Neither reptiles nor any appropriate ancestors are known prior to the Lower Pennsylvanian. Because of the absence of any true ancestors, the nature of the amphibian‐reptilian transition must be studied on the basis of amphibians contemporary with the early reptiles. The Permian seymouriamorphs have long been accepted as relicts of the group which gave rise to reptiles, althoughSeymouriaitself is specialized in many features of its anatomy. The Middle Pennsylvanian genusGephyrostegusappears to resemble much more closely the anatomy expected in the ancestors of reptiles. This genus forms the basis for consideration of the anatomical, physiological and behavioural changes which culminated in the origin of reptiles.Study of the earliest known reptiles and their closest relatives among contemporary amphibians indicates that the initial adaptation leading to the emergence of the class was assumption of a terrestrial habit, with accompanying small body size. The small body size of the immediate ancestors of reptiles would have made it possible for them to produce sufficiently small eggs that they could develop in damp places on land without initially being supported and protected by extraembryonic membranes. The rapid increase in body size in all lineages of Pennsylvanian reptiles indicates the prior development of an amniotic egg.Fundamental to the emergence of reptiles was modification in the jaw mechanism from the kinetic inertial system of amphibians to a static pressure system. The latter was presumably developed in order for the developing reptiles to utilize more active terrestrial prey. This change in the jaw mechanism is reflected in the reorganization of the palate which serves as a morphological basis for denning the establishment of reptilian status. At approximately the same stage as the change in palatal structure, the definitive reptilian vertebral pattern was developed.The apparent closure of the otic notch and the probable reorientation of the stapes in the amphibian‐reptilian transition presumably resulted from the decrease in relative skull size and do not appear to be related to any change in hearing ability. The tympanum probably maintained the same relative relationship with the squamosal and supratemporal throughout this transition.On the basis of the present fossil record, all adequately known Palaeozoic reptiles appear to have had a common ancestry among the predecessors of the known gephyro‐stegids. The family Diadectidae is the only important group whose specific relationships cannot be established.On the basis of this study, the following taxonomic changes are suggested: the family Limnoscelidae should not be included among the captorhinomorphs. The seymouria‐morph concept should be restricted to forms having the specializations ofSeymouria,the discosauriscids and kotlassids. Gephyrostegids should be specifically excluded from the Seymouriamorpha and should be included in a separate taxon among the anthra‐cosaurs of equal rank with embolomeres and

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01218.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1969.tb01219.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY