摘要:

The morphodynamics ofProrocentrumspecies have been studied comparatively in cultures and in plankton. Plankton populations show little morphological variation. In cultures a variety of forms, often similar to other species ofProrocentrumwhich have been described from distant seas, are found. Morphological variation inProrocentrumspecies depends upon various life phases, individual features of the clones, and various types of the cysts. Formation of morphological aberrants is also affected by aging of cultures. All protoplasmatic structures, including the cell membrane, possess their own particular features, changing in the course of the life cycle. Since both physiological and morphodynamic metabolisms are inseparable in their activities, it is useful to complete taxonomic diagnoses with physiological observations. Five new species are described:Prorocentrum cordiformis, Prorocentrum pomoideum, Prorocentrum pyrenoideum, Prorocentrum redfieldi, andProrocentrum levanlinoides. Morphodynamics inProrocentrum micansandProrocentrum scutellumwas also studied. Most of the observations were made in vivo. Specific morphological differences in form and structure of protoplasmatic organelles were demonstrated in each species concerned. An attempt was made also to base taxonomic diagnoses upon the apical tooth, trichocysts, and membrane structure.

ISSN:0008-4026    

DOI:10.1139/b59-001

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

This paper describes the action of the metal-chelating reagent disodium versenate on the epidermis of livingBrassicaseedlings. Striking abnormalities were produced, characterized by the repression of root-hair formation and by swelling and deformity of the epidermal cells. The results of the present study are briefly discussed in the light of evidence obtained by use of the electron microscope.

ISSN:0008-4026    

DOI:10.1139/b59-002

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Solanum balbocastanumDun. was collected extensively throughout its range in Mexico and Guatemala. Experimental self- and cross-pollinations showed that the species is highly self-sterile and consists of cross-sterile and cross-fertile individuals. Self-sterility may be due to the presence of incompatibility factors or to triploidy. Authentic hybrids were produced betweenS. bulbocastanumandS. trifidumCorrell, and betweenS. bulbocastanumandS. pinnatisectumDun.After inoculation with race 1.2.3.4 ofPhytophthora infestansthree types of reaction were observed among 1148 seedlings ofS. bulbocastanum: immunity with no perceptible lesions, resistance expressed by non-sporulating lesions of the hypersensitive type, and susceptibility indicated by large sporulating necrotic lesions. Seedlings resistant to an isolate of race 1.2.3.4 of Canadian origin did not always show the same level of resistance to a Mexican isolate of the same race. Varying degrees of field resistance were observed among seedling plants, while tuber-propagated plants were generally field immune.Solanum bulbocastanumis considered a mixture of resistant and susceptible genotypes.

ISSN:0008-4026    

DOI:10.1139/b59-003

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Spores ofAlternaria solanicarried on glass fiber filter disks were employed in a study of the fungicidal activity of the fumigant, methyl bromide. Following exposure to the fumigant the disks, carrying the spores, were placed in a spore germination medium and the results subsequently evaluated by direct mortality counts. Linear probit-log dose regression lines were obtained by this procedure. The effectiveness of the fumigant was found to be dependent on the vapor pressure of water in the atmosphere and to be independent of temperature. The results suggest that humidity operates through its effect on spore hydration.

ISSN:0008-4026    

DOI:10.1139/b59-004

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Nuclear behavior in the life cycle ofGanoderma lucidum(Leyss. ex Fr.) Karst., a common polypore in West Bengal, India, has been studied. Each young basidium is binucleate and the nuclei soon fuse to form a syncaryon which undergoes three successive divisions, of which the first is reductional, to produce eight daughter nuclei. Four nuclei pass into the four spores, one into each, and the other four, remaining within the basidium, finally degenerate. Thus at first each basidiospore contains one nucleus which may or may not divide further. On germination, the spores give rise to primary mycelia with uninucleate or multinucleate cells. Secondary mycelia, formed by the union of two compatible primary mycelia, have nodose-septate hyphae in which most of the cells are dikaryotic although cells with more than two nuclei are not uncommon.The chromosome number, counted from metaphasic plates, has been found to be 10 = 2n.

ISSN:0008-4026    

DOI:10.1139/b59-005

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

To provide a basis for relating biochemical findings on isolated cell fractions to cytological structurein situ, embryos of pea and wheat were fixed with osmic acid, sectioned, and observed in phase-contrast and electron microscopes. The nuclei of all cells were similar, showing nuclear membranes, chromosomes, and prominent nucleoli. The cytoplasm contained highly developed structure which presumably reflected the incipient growth condition of the cells. Several cytoplasmic components were common to both embryos: small dense granules, endoplasmic reticulum, mitochondria, presumed proplastids, amyloplasts, irregular bodies, plasma membranes, and plasmodesmata. The small dense granules, presumably ribonucleoprotein particles, occurred profusely, both free and in association with extensively developed endoplasmic reticulum. These particles are probably responsible for the microsomal fractions obtainable from embryos and seedlings. The mitochondria were usually relatively small (0.25−0.5 μ diameter) although groups of very long (5 μ) ones were occasionally found. Bodies resembling mitochondria in size and shape, but lacking cristae, were present and represent either immature mitochondria or proplastids. Reserve material occurred as starch in structurally complex amyloplasts and possibly as protein in the irregular bodies. In addition to these structures cells of the wheat embryos remote from the meristems contained prominent cytoplasmic bodies classified as "dense" and "thick-walled". The dense bodies probably represent stored lipids while the significance of the thick-walled bodies, which showed a variety of forms, is unknown.

ISSN:0008-4026    

DOI:10.1139/b59-006

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The chromosome numbers of plants of theAchillea millefoliumcomplex from 27 locations in North America are reported. The levels of polyploidy found are correlated with diameters of the pollen grains. Measurements of pollen grains from more than 300 herbarium specimens are used as an indication of the occurrence of tetraploid and hexaploid species ofAchilleain Canada. The results of some crossing experiments are also reported. It is concluded that the commonAchilleaof North America is tetraploid and is the nativeA. lanulosaNutt. It extends from the Pacific to the Atlantic coasts, as far south as California in the west and Pennsylvania in the east, and to northern Canada and Alaska. Another native species, hexaploidAchillea borealisBong., extends along the Pacific coast from southern California to the Aleutian Islands and along the northern shorelines of Alaska and Canada. A Eurasiatic hexaploid,A. millefoliumL. s. str., has been sparingly introduced into Newfoundland, Prince Edward Island, Nova Scotia, and perhaps elsewhere along the Atlantic seaboard. In eastern Canada a male-sterile purple-flowered hexaploid also occurs. This hexaploid escapes from cultivation and forms localized patches. It undoubtedly has been selected from the EurasiaticA. millefoliumL. s str.

ISSN:0008-4026    

DOI:10.1139/b59-007

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The chromosome numbers of 38 Canadian weeds are reported and the significance of some of these numbers is discussed. Counts obtained on material ofIva xanthifoliaL., 2n = 36,Erysimum hieraciifoliumL., 2n = 48, andNepeta catariaL., 2n = 34, differ from those obtained by previous workers. The chromosome numbers of the following species have not previously been reported:Rumex transitoriusRech. f., 2n = 20;R. triangulivalvis(Danser) Rech. f., 2n = 20;R. verticillatusL., 2n = 60.

ISSN:0008-4026    

DOI:10.1139/b59-008

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Observations in the field and the results of inoculation experiments show that perennial needle rust of fir (Abiesspp.), known asPeridermium pseudo-balsameum(Diet. & Holw.) Arth. & Kern, is caused byUredinopsis hashiokaiHirats. f. andU. pteridisDiet. & Holw. (U. macrospermaMagn.), which complete their life cycles on bracken fern (Pteridium aquilinum(L.) Kühn var.lanuginosum(Bong.) Fern.). The pycnial and aecial states ofUredinopsis hashiokaiare described, and for the first time the life histories ofU. hashiokaiandU. pteridisare presented. The two species are indistinguishable from each other in life history, host relationship, and morphology of most of the spore states; they differ from each other in their geographical distribution and in the morphology of their urediniospores. It remains unknown which of the two species ofUredinopsisrepresents the perfect state ofPeridermium pseudo-balsameum.Uredinopsis asperaFaull proved to be a later synonym ofU. hashiokai. U. hashiokaiis noteworthy because of its similarity toU. pteridis, and both species are unusual in development of their spore states on fir, particularly in the long periods required for maturation of the aecia, which are produced from localized, perennial mycelium 4 to 11 months after infection inAbies lasiocarpa(Hook.) Nutt. andA. grandis(Dougl.) Lindl. respectively.

ISSN:0008-4026    

DOI:10.1139/b59-009

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Results from inoculation experiments have shown that the needle rust of hemlock (Tsugaspp.),Caeoma dubiumC. A. Ludwig, represents the aecial state of a new race ofMelampsora epiteaThuem. for which the nameM. epiteaf. sp.tsugaef. sp. nov. is proposed. This race differs morphologically from most species ofMelampsoraand from some races ofM. epitea. It is indistinguishable, however, from the fir rustM. abieti-capraearumTub. (another race ofM. epitea), from which it differs in its aecial hosts only. An account of the taxonomy, morphology, and life history ofM. epiteaf. sp.tsugaeis presented for the first time.

ISSN:0008-4026    

DOI:10.1139/b59-010

出版商:NRC Research Press    

年代:1959

数据来源: NRC