摘要:

The investigation reported herein is an effort to secure information through the use of cytological methods, which may assist in providing a better understanding of the true relationships of species and varieties within the genusMedicago, and to compare cytologically, in a general way, this genus with the related generaMelilotusandTrigonella. In order to emphasize the present unsatisfactory taxonomic situation the morphological characters of the three genera are described and the taxonomic classifications of the species for each is reproduced as presented by Taubert (49). Classifications forMedicagoby Dr. Candolle (11) and by Hegi (15) are also outlined for purposes of drawing attention to certain discrepancies between the classifications ofMedicagoby Taubert and by Hegi. Reference is made to specific taxonomic difficulties inMedicago. The general distributions of the three genera are given.In the section of the paper on "Cyto-taxonomic relations", an attempt is made, first, to point out five cytological principles which provide the philosophical foundation for cyto-taxonomic research; second, to summarize some of the background of literature which serves for the establishment of these principles; and third, to review a few papers reporting outstanding cyto-taxonomic investigations which demonstrate the applicability of the method. Previous cytological work onMedicagoandMelilotusis then outlined. Details of observations concerning somatic chromosome morphology and numbers are recorded for 23 species and five varieties of two additional species ofMedicago, for four species ofMelilotusand for three species ofTrigonella. A summarized statement of all cytological observations is given.In the discussion the following topics are considered in the light of the cytological data secured: general morphology of the somatic chromosomes and chromosome numbers found in the species studied, chromosome numbers and the annual or perennial habit inMedicago, different races inMedicago falcata, hybrid origin ofMedicago media, taxonomic relations ofMedicago lupulina, Medicago carstiensis, Medicago obscura, Medicago rigidulaandMedicago arabica, and varieties ofMedicago hispida. A few points of purely cytological interest are also discussed, viz., tetraploid chimeral areas, nucleolar remnants, and the peculiar anaphase chromosomes in somatic divisions.In general it is concluded that these cytological studies have yielded information which can be utilized very effectively in clearing up some of the taxonomic problems, particularly, in the genusMedicago. It is predicted that the cytological information will also be useful to plant breeders who may contemplate interspecific hybridization among any of the species studied.

ISSN:1923-4287    

DOI:10.1139/cjr30-040

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Examination of soil from different locations, extending over a twelve-month period, for the presence of sugar-tolerant yeasts capable of fermenting honey, showed that only in the case of apiary ground was the soil regularly infected by such organisms. Ordinary field soil is not to be considered a primary source of infection of honey, sugar-tolerant yeasts not being regarded as members of the normal soil microflora. Sugar-tolerant yeasts, in apiary soils, are able to remain viable through the winter in frozen soil, but are cold-enduring rather than psychrophilic. From the soil 166 cultures of sugar-tolerant yeasts were isolated and classified. These were found to represent seven types considered as six species with one sub-species, three being types found in fermented honey. A description of the yeasts is given.

ISSN:1923-4287    

DOI:10.1139/cjr30-041

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Glycerol α-monochlorohydrin has been found to be an effective extraction agent for the removal of lignin from spruce wood meal. Previous evidence for the view that a compound is formed between the lignin and the extraction medium is supported by the results of methoxyl and halogen analysis, and those of hydrolysis.

ISSN:1923-4287    

DOI:10.1139/cjr30-042

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

A new adiabatic calorimeter equipped with a radiation thermel is described. Measurements of the heat capacity of ice over various temperature ranges are presented in order to illustrate the method of handling the calorimeter and to find the order of accuracy of this piece of apparatus. The latent heats of fusion of ice at 0 °C. and at − 3.0 °C. are found.The novel feature of the new calorimeter is shown to be the radiation thermel for indicating any difference between the temperatures of the inner calorimeter and the outer bath. This instrument consists of a multiple junction thermocouple of which one set of junctions receives heat from the inner calorimeter vessel by radiation. The accuracy of the calorimeter is shown to depend on the magnitude of the temperature drop in the inner vessel and on the method for reading the temperatures involved. In the experiments with ice a probable accuracy of about 0.2% is obtained with temperature drops of the order of 2°, measurement of which is made with a Beckmann thermometer.

ISSN:1923-4287    

DOI:10.1139/cjr30-043

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Under laboratory conditions a very large fermentative evolution of carbon dioxide takes place in logs during both seasoning and flotation, increasing their gas phase and their buoyancy. The principal changes which take place in the water-gas system of logs during seasoning and flotation have been followed by weight measurements and analyses showing water distribution.End penetration has been shown to be an important factor in sinkage, at any rate when evaporation from the upper surface of the log is considerable. Bolts, 2 ft. 8 in. long gained, during flotation for 8 months, from two to three times as much water when their ends were unpainted as when they were painted. End penetration, combined with evaporation, was found to create through the log a current of water which helps to transport dissolved gases, and to reduce the volume of the gas bubbles held in the cells. It thus acts doubly towards reducing buoyancy by replacing evaporation loss and by facilitating the escape of the imprisoned gases.

ISSN:1923-4287    

DOI:10.1139/cjr30-044

出版商:NRC Research Press    

年代:1930

数据来源: NRC