摘要:

Growth in the various tissues of the fruit of a McIntosh Red and a Wagener tree, both self-pollinated, is compared. For several days succeeding pollination no increase in fruit size is apparent. Fertilization is followed by general cell division and cell enlargement. The period of cell division varies with the tissue and with the variety. Final cell size is reached first by the cells of those tissues near the centre of the apple. Impressed upon the fundamental pattern of growth is the localized activity of the primary vascular bundles, the cambia of which add cells to the ground tissue. Angulation in the Wagener is accentuated by this activity. With the exception of cells of the epidermis, final cell size is approximately equal in comparable regions of the two varieties. Differences in regional extent are due to differences in numbers of cells in that region.

ISSN:1923-4287    

DOI:10.1139/cjr41c-037

出版商:NRC Research Press    

年代:1941

数据来源: NRC

摘要:

A detailed study of the direction of chromonema coiling at first meiotic metaphase and anaphase inTrillium erectumL. has shown that reversals in direction of coiling occur in the attachment region, at chiasmata, and in other regions. They occur with random frequency at the attachment. There is an average of two reversals at each "effective" chiasma. In other regions reversals were observed with a frequency of one in 17 gyres.The results indicate that there is no inherent pattern determining the direction of coiling and that reversals are effected by various interrupting mechanisms.

ISSN:1923-4287    

DOI:10.1139/cjr41c-038

出版商:NRC Research Press    

年代:1941

数据来源: NRC

摘要:

Twenty-four collections of Norway spruce cuttings were taken, seven about the time new growth was forming, six at semimonthly intervals rom July to September, four during October, and seven at monthly intervals during the winter to April, and were propagated in outdoor frames in several media. The proportion of cuttings rooting in sand was low for the summer collections but reached 80% or higher for collections made in September and October. The addition of sedge peat effected rooting of 90% in collections taken throughout summer and autumn, and increased the number of roots, length of root, and the development of new growth. Sphagnum peat added to the sand was also slightly beneficial but, for propagation, much inferior in effect to the sedge type of peat. Varying the proportion of peat or the texture of the sand had no significant effect except on the length of root, which was greater in those media rich in peat. Cuttings stored over winter or taken in spring did not respond well.

ISSN:1923-4287    

DOI:10.1139/cjr41c-039

出版商:NRC Research Press    

年代:1941

数据来源: NRC

摘要:

By suitable treatment the somatic chromosomes of a number of plants may be shown to be longitudinally differentiated as to size and staining capacity. Certain well defined regions appear at metaphase and anaphase to be either understained or of reduced diameter or both.Exposure to cold has been found to produce these regions in two varieties of rye and three species ofTrillium.The positions of these differential segments have been found to be highly specific for different chromosomes and species.During a 96-hr. period of exposure to cold the number of chromosomes affected and of differential segments per chromosome increases inT.erectumL.After cessation of treatment the chromosomes resume their normal appearance within a few hours.Homologous chromosome pairs often differ in number, size, and position of affected regions. On the basis of data presented in this paper, these differences cannot be taken as conclusive evidence that these pairs are genetically different.

ISSN:1923-4287    

DOI:10.1139/cjr41c-040

出版商:NRC Research Press    

年代:1941

数据来源: NRC

摘要:

The parthenocarpic development of strawberry fruits was induced by spraying unpollinated blossoms with solutions of indolylbutyric acid, 1-naphthylacetic acid, and colchicine, and by dusting the blossoms with powdered acenaphthene. Fruits also developed from blossoms that had not been directly treated. This is explained on the basis of translocation of the chemical, or some other substance, from treated to untreated blossoms.It is suggested that colchicine, and possibly the phytohormones, induce parthenocarpy by acting as mobilizers of another substance or substances that move into the ovary and there initiate development.

ISSN:1923-4287    

DOI:10.1139/cjr41c-041

出版商:NRC Research Press    

年代:1941

数据来源: NRC