摘要:

The effects of latitude, burning, and pruning on the growth cycle of the blueberry were studied and found to be as follows. The morphology of the growth cycle and the sequence of morphological changes were not altered by any of the factors considered. For spring and summer, a north and south difference of one hundred and fifty miles had no greater effect than that which is regarded as "seasonal". Burning and pruning delayed the spring and summer growth by about two weeks. For the late autumn and early winter, there was some evidence that morphological changes occurred in the distal florets during that period, but for the "depth of winter", that is from mid-December till the end of February, the winter bud was a morphological complex that, with the exception of the apical floret, always had the same structure regardless of latitude, burning, or pruning and this structure was the same as that found in normal plants during that season.

ISSN:0008-4026    

DOI:10.1139/b53-001

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

An organism isolated from soil, cultivated in a simple medium containing only inorganic salts and sugar, was found to synthesize an essential growth factor that was nutritionally equivalent to soil extract in promoting the growth of an organism for which the latter was hitherto considered essential. The factor could not be replaced by the B vitamins, purines, pyrimidines, or other growth-promoting substances tested (including derivatives of various natural products) with the exception of hemin, which evoked but a partial response, and concentrated liver extract, the effect of which was not attributable to vitamin B12. Partially purified material from the metabolic liquid showed distinct growth-promoting activity at a concentration of 0.1 p.p.m. The organism requiring the growth factor, as well as that synthesizing it, both pleomorphic bacteria of the "soil diphtheroid" type, were found to be hitherto undescribed species. They are considered to be most appropriately assigned to the genusArthrobacter, as proposed by Conn and Dimmick, and are named, respectively,Arthrobacter terregensn. sp. andArthrobacter pascensn. sp.

ISSN:0008-4026    

DOI:10.1139/b53-002

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The adaptation of a percolation technique to the study of the production of antibiotics in soil is described. Antibiotic activity is determined by assays of a continuously circulating soil solution without disturbing the soil sample itself. The advantages of this technique over existing methods of study are discussed. Results are presented illustrating the production of antibiotics in sterile soil by aPenicilliumsp. and two unidentifiedStreptomycesspp.

ISSN:0008-4026    

DOI:10.1139/b53-003

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

One hundred and fourteen bacterial cultures representing most of the species in theBacillusgenus were tested for the production of extracellular barley gum cytase. Assays were made on shake-flask cultures grown on a medium containing glucose and yeast extract. Although all the organisms had some enzymatic activity, certain strains ofBacillus subtilisgave the best yields of cytase. On a medium with asparagine as the sole nitrogen source even higher yields were obtained. The crude cytase preparations were stable and after freeze-drying most of the original activity remained.

ISSN:0008-4026    

DOI:10.1139/b53-004

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A survey of the course of carbon dioxide output of potato tubers upon transfer from air to nitrogen shows that the form of drift in nitrogen undergoes metamorphosis with the lapse of time between harvest and the anaerobic experience. A stable form is attained about three months from harvest.On restoration of air after nitrogen a temporary outburst of carbon dioxide occurs, and both form and magnitude of this after-effect change with time elapsed after harvest. The magnitude is also influenced by the duration of anaerobiosis. At any season, increased time in nitrogen produces an increased after-effect of more than proportionate magnitude. The rate of carbon dioxide output in air after nitrogen ultimately becomes steady, but is not necessarily equivalent to that preceding anaerobiosis. For the space of about three months, subjecting a tuber to nitrogen for two days or more at 22 °C. causes the ultimate rate of carbon dioxide output in air to remain well above that preceding anaerobiosis, while it bears a constant ratio to the final rate in nitrogen before air was restored. This permanent displacement of the rate in air is not at any time brought about by an anaerobic period of only one day.The nature of the drifts in metabolic state of the tubers that underlie these metamorphic changes in response to a period of anaerobiosis is still under investigation.

ISSN:0008-4026    

DOI:10.1139/b53-005

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The multiplication of fusiform initials in the cambium is accompanied by extensive loss or transformation of these cells. A few of the failing cambial cells lapse into maturation quickly, but the majority are transversely subdivided with varying proportions of the segments surviving and undergoing ultimate conversion to ray initials. The loss or conversion is attended with reduction in cell size. Increase in cell volume lags behind cell division during the periclinal divisions of the transitional period. The tangential dimensions of the successively formed cells are continuously reduced, and sometimes radial expansion is also retarded, especially toward the cell tips. Simultaneous shortening of the cells is due to alteration in cell shape combined with asymmetry in periclinal division such that daughter cells of unequal lengths are produced. Repetition of the process, the smaller cell functioning as the initiating cambial cell in each instance, results in continued shortening.

ISSN:0008-4026    

DOI:10.1139/b53-006

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Crystalline sucrose has been isolated from cleared alcoholic extracts of mature wheat leaves by precipitation as the barium salt. The crystals were positively identified by melting point, X-ray diffraction analysis, and glucose–fructose ratio as well as by conventional analytical techniques. The evidence for the presence of sucrose in the wheat leaf has been corroborated by chromatographic analysis of leaf extracts. It is concluded that sucrose forms the bulk of the soluble sugar reserve of this tissue.

ISSN:0008-4026    

DOI:10.1139/b53-007

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The press juice from mature seedling wheat leaves possesses a high thermo-labile activity in the inversion of sucrose. It is concluded that an invertase is present. The active material is not associated with the coarse particles of the protoplasm but is soluble in the sap and in that condition is very stable in the cold. It is, however, sensitive to drying and precipitation. Some kinetic characteristics of this enzyme resemble those of invertases from other sources. But the Michaelis constant is small by comparison with that of yeast invertase and therefore a relatively high affinity of the leaf enzyme for its substrate is indicated.

ISSN:0008-4026    

DOI:10.1139/b53-008

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Using aircraft, studies were carried out on the numbers of bacteria and fungi in the air and 10 separate flights were made during 1948 and 1949 covering territory between Goose Bay, Labrador, and Fairbanks, Alaska. Quantitative samples were taken on agar plates, and silicone coated slides in the McGill G.E. Sampler, as well as in glass wool filters and the results correlated with definite air masses. A comparison of methods showed that the McGill G.E. Sampler gives higher and more consistent results for the total viable count than the filters. Silicone coated slides give the total fungus count including nonviable spores and spores that will not grow on the agar plates.From various air masses and during different times of the year, there was considerable variation in the average number of bacteria and fungi found. The highest fungus count was 23.6 per cu. ft. and the lowest 0.01. There was less variation in the number of bacteria, the highest being 5.6 and the lowest 0.2 per cubic foot. The highest fungus counts were found in continental polar air during the summer months while for the bacteria the highest counts were found in Pacific polar air during the spring and fall. The bacteria and fungi isolated were all soil types.

ISSN:0008-4026    

DOI:10.1139/b53-009

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The numbers of bacteria and fungi in arctic air were determined by daily sampling at Churchill, Man., during July and August 1950, and in three flights, one to Baker Lake, N.W.T., and the remainder to Resolute Bay, N.W.T. Of the three samplers which were used simultaneously the G.E. Bacterial Air Sampler gave slightly higher readings than the Bourdillon Slit Sampler, while the filter gave low readings throughout.Daily averages of bacteria at ground level ranged from 0.9 to 30.1 per cu. ft., and in the flight to Resolute Bay from 0.3 to 0.9 per cu. ft. while the comparable readings of the fungi were 0.5 to 4.4 and 0.01 to 0.7 per cu. ft. with the slit sampler. Considerable variation occurred in ground level samples, not only from day to day but throughout the day. Silicone slide studies revealed high numbers, up to 115 per cu. ft., which includes a high proportion of nonviable fungus spores. Most of the organisms are soil inhabiting forms but some fungus parasites were present, chiefly as smut (Ustilago) spores. Evidence indicates that winds originating in the south carry large numbers of organisms northward, many of which are nonviable when they reach the arctic, while north winds of polar origin contain very low numbers even in the summer.

ISSN:0008-4026    

DOI:10.1139/b53-010

出版商:NRC Research Press    

年代:1953

数据来源: NRC