摘要:

SUMMARYCultures of Anabaena cylindrica Lemm. and Eucapsis sp. were harvested, freeze‐dried, and prepared for electron microscope studies. A comparison of the freeze‐dried preparations was made with control specimens not freeze‐dried. Fixation and embedding were according to the Ryter and Kellenberger technique. The photosynthelic thylakoids of the freeze‐dried cells were more distinct and less distorted than those of the control cells. Freeze‐dried Eucapsis sp. cells exhibited a prominent mucous capsule, whereas in the nonfreeze‐dried, no such capsule could b

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04652.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYComparisons of various methods and method modifications for treating water samples to render them free of seston prior to analysis of dissolved organic matter have corroborated a number of suspected sources of error. Among the more important points arising from this study arc: 1. All cellulose ester filters must be washed to remove elutable carbon. 2. In some instances filtration to dryness may produce artifacts resulting from cell injury. 3. A significant difference in filter retention can result between 0.45 and 0.22 μ membranes. 4. Among the methods most satisfactory are wet filtration through 0.22 μ pre‐washed Millipore membranes and continuous‐flow centrifugation at ca. 10,000x gand 100 cc/min flow rate, both of which have their inherent weaknesses and limitations. 5. Regular centrifugation does not remove some planktonic organisms which have considerable buoyancy, or organic substances may somehow be released by cells without producing morphological damage.The newly developed bio dialysis technique for dissolved organic matter collection consistently yielded lower values than continuous‐flow centrifugation. In contrast, biodialysis yielded lower values for pond water and higher values forScenedesmuscultures than the best filtration method. Evidence suggests that biodialysis will be useful as both a supplementary and, in some zuays, more accurate method in studies of dissolved organic

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04653.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYThe distribution of phyioplankton in a double‐cell sewage lagoon at Hallam, Nebraska, was studied in relation to physical, chemical, and biological factors during the summer and fall of 1965. Sixteen species of algae were recorded in the first and more organically rich of the two physically similar ponds, with 28 species recorded in the second pond. Population sizes were always greater in the first pond due to reduced grazing during the summer and large quantities of ammonia‐nitrogen during the fall. The dominant algal species in both ponds on nearly all sampling dates wasAnkistrodesmus falcatusv.acicularis.Declines in this population occurred with high organic pollution and heavy grazing. Both ponds had severe reductions in algal numbers during late October due to heavy grazing by the rotiferBrachionus.The distribution of phytoplankton in the Hallam ponds is compared to that of other sewage ponds in the United States, and the general pattern which emerged is discus

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04654.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYSexual reproduction inC. moniliferumis described for the first time. The morphology of conjugation is quite like that ofC. ehrenbergii.Homothallic strains of both species usually produce single zygospores between daughter cells that have just divided. However, 2 homothallic clones ofC. moniliferumform twin zygospores between conjugants which have paired before division and conjugation. This has not been observed inC. ehrenbergii.Heterothallic strains of both species form twin zygospores in the same manner. Heterotfiallisrn seems a well‐established feature in both species. Germination and the survival of 2 products of meiosis arc typical of other desmids which have been investigate

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04655.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYThe mineral component of the marine green algal genusHalimedais the orthorhombic calcium carbonate (aragonite); its presence appears to be a generic characteristic.Tydemania expeditionisalso precipitates aragonite in contradistinction to species of the red algaCorallinawliich precipitate calcium carbonate of the hexagonal form (calcite). The analyses are based on x‐ray diffraction methods. Although other inorganic substances arc present, the amounts are minor and probably represent contaminants. Specimens that are to be studied for mineral components should not be stored in formali

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04656.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04657.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYSweets Lake, British Columbia, is the type locality for plants originally described asChara buckellii.Plants from this locality liave been crossed successfully to a second clone from Laguna La Drava, Argentina, the type locality forNitellopsis bulbillifern.Plants from both clones were also crossed with others from Texas, New Mexico, and Wyoming that agree in most respects with. Robinson's original description of C.longifolia.On the basis of such crosses we suggest that all 3 taxa are biologically conspecific. There is no evidence, either from the field or experimental crosses, of gene flow betweenC. longifoliaandC. hornemannii;the two should be considered separate species.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04658.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYThe expansive, reticulate cliloroplasts of the filamentous green algaOedogonium tardiacumwere found to contain microtubular elements with an outside diameter of about 270 A. These microtubules have been examined in the chloroplast stroma of vegetative cells, zoospores, zoospore germlings, and eggs. They may occur singly or, more commonly, in groups or bundles of 2 to as many as 30. In longitudinal section these microtubules show a regular pattern of slightly oblique cross striations and the margins appear rough. They bear little structural resemblance to the more familiar and slightly smaller microtubules found in the cytoplasm external to the cliloroplasts. Their overall appearance suggests that each is constructed of 2 helically wound, ribbon‐like units that are approximately 155‐175 A broad and 45‐55 A thick. The 2 units of this proposed double helix appear to lie in juxtaposition at a pitch of 17‐27 deg. The dimensions of each unit, or helix, are such that it could conceivably be constructed of 3 filamentous subunits similar to those already described in the literature for other microtubular e

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04659.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYThe algal symbionts ofHydra viridisare 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‐livingChlorella.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

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04660.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

SUMMARYA new species ofNitellabelonging to theN. flexilisspecies group is described. The neiu species shows definite relationships toN. flexilis, N. opaca, N. missouriensis,andN. mirabilis.Relationships of the new species toN. acuminataare also discussed.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1967.tb04661.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY