摘要:

A fungus isolated from naturally brown-stained red pine sapwood was found to produce characteristic chocolate brown stain in sterilized red pine sapwood in culture; it is identified as a species ofCytospora. The fungus develops in the ray parenchyma, may proliferate in the tracheids, but penetrates the walls only through the pits. A technique is described for producing brown stain in culture in sticks of the size required for static bending and toughness tests. Two series of sticks were subjected to each test; the samples used were end-matched sticks in groups of three, which provided a green control, sterilized control, and specimen stained in culture byCytosporasp. The results showed some variation in the relative strength of samples in different groups, but a statistical analysis indicated that the effect ofCytosporasp. on both bending strength and toughness is negligible.

ISSN:0008-4026    

DOI:10.1139/b52-027

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Thirty-five cultures ofBacillus stearothermophilushydrolyzed five starches under various cultural conditions. Hydrolysis occurred regardless of the type, brand, or batch of starch; regardless of the initial pH or of the subsequent pH changes of the medium. Starch in broth was better attacked than in agar media. Some cultures hydrolyzed 0.5%, but not 1% starch; others hydrolyzed easily 10% soluble starch. Length of incubation was important. Certain cultures never formed acid or sugar from starch. Dextrinization was a more reliable indication of starch hydrolysis than was the formation of acid or sugar. Soluble starch gave more consistent results in repeated experiments than did nonsoluble starches. The type of protein medium determines strongly the formation of amylase. Trypticase was the best commercial medium, yeast extract came second. The other 10 media yielded fewer amylolytic cultures. Yeast extract added to media enhanced amylase formation, except with trypticase. Tryptose, proteose-peptone, and neopeptone inhibited the growth of most cultures.

ISSN:0008-4026    

DOI:10.1139/b52-028

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

The frequency with which 20 different monosomes of the common wheat variety, Chinese Spring, formed micronuclei in pollen quartets was determined. It was found that unless the study was made at an early developmental stage characterized by a distinct cell wall surrounding the quartets, the counts were unreliable, because some micronuclei were lost. The frequency of micronucleus formation was similar for anthers of a floret, florets of a spike, and plants of a monosome. Among the monosomes studied, there were three groups of three and four of two in which the total frequency of quartets with micronuclei, and the distribution of numbers of micronuclei per quartet, were strikingly similar. In the case of the groups of three, two monosomes were from theAandBgenomes while one was from theDgenome. This is interpreted as evidence of homoeology of chromosomes of a group and also that such chromosomes have undergone less change than those that do not form such series.

ISSN:0008-4026    

DOI:10.1139/b52-029

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Experiments have been performed on seedlings of many species of cultivated plants with a new Tian-Calvet microcalorimeter installed at the University of Montreal. The characteristic elements of the curve of thermogenesis are first described on wheat germinations and their variations discussed in function of temperature, preliminary dehydration, substances in solution in the soaking liquid: salts, alcohol, auxins, etc. Then comparisons are made between germinative thermogeneses of oats, rye, barley, corn, flax, tomatoes, etc., showing the numerous possible applications of microcalorimetry in plant studies and agronomy.

ISSN:0008-4026    

DOI:10.1139/b52-030

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

"Malic" enzyme isolated from the cytoplasm of parsley and sugar beet leaves was linked with illuminated spinach chloroplast fragments to effect photosynthesisin vitro. The model photosynthesis system containing excess "malic" enzyme was not inhibited by 5 × 10−4 Mhydrogen cyanide. The "malic" enzyme system was inhibited by cyanide, however, at very low enzyme concentrations. The richest source of "malic" enzyme found in this study was the mature parsley leaf. Expressed on the same basis, the enzymatic capacities of parsley leaf "malic" enzyme and the Hill reaction capacity of isolated spinach chloroplasts are of similar magnitude. Higher "malic" enzyme and oxalacetic carboxylase activities were found in purified extracts of parsley leaves than in the corresponding root extracts. Oxalacetic, oxalsuccinic, α-ketoglutaric, and pyruvic carboxylases were not inhibited by 10−3 Mhydrogen cyanide. The α-ketoglutaric and pyruvic carboxylases were much less abundant in leaves than in other plant organs; formic dehydrogenase was not detected in leaves although it is abundant in seeds. Glutamic carboxylase was found in the cytoplasm of wheat and sugar beet leaves, and with the aid of C14O2was shown to be only weakly reversible. No evidence was obtained for the presence in leaf extracts of an enzyme, or mixture of enzymes, capable of decarboxylating phosphoglyceric acidin vitro.

ISSN:0008-4026    

DOI:10.1139/b52-031

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

This is a taxonomic study ofCintractiaspp. on nearly one hundred host species, mainly in Canada, northern United States, and southern Alaska. Coverage is very incomplete for northern Alaska, Greenland, and parts of the Canadian arctic archipelago. Eighteen species and varieties are recognized including one new species,Cint.atratae, and four new varieties,Cint.carpophilavars.kenaicaandverrucosaandCint.caricisvars.intermediaandacutarum. Two recombinations are made. The biology and phylogeny of the group are also discussed.

ISSN:0008-4026    

DOI:10.1139/b52-032

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

In order to place phytogeographical regions on a world basis, it is necessary to invoke the zone concept. For example, a botanist who studies the flora of some parts of the USSR, Alaska, Quebec, and Scandinavia recognizes many similarities, if not analogous floras: before considering the local differentiations which distinguish regional floras, he recognizes on first sight the "arctic" aspect. The tendency of phytogeographers, foresters, and biologists in general is to overlook the zonal division of the world from the arctic zone to the tropical zone and consider the regional aspects only. In a zonal division of Quebec, there are thetemperate zone, grossly south of the 50° lat. N.; the subarctic zone, between the 50° and the 55° approximately; thehemiarctic zone, between the 55° and the absolute limit of trees; and finally thearctic zone, north of the 58°. Thehemiarctic zone, described herein, and consisting principally of the habitat commonly called forest–tundra, is not formed of transitional habitats between those of the subarctic zone and those of the arctic zone, but made up of purely arctic patches (from 60 to 90% of the surface) imprisoned in a net of subarctic forest strips. The hemiarctic zone instead of being merely a mixture of arctic and subarctic plants, may be compared then to an "emulsion" of arctic and subarctic habitats. This "mixed" zone, highly convenient for phytogeographical purposes, finds its justification in biological and ciimatological data. For the distinction of the zones, we must not consider only the arborescent flora but all other expressions of life as well. From tentative studies, it is quite evident that a distinction of the zones based on limited floristic aspects,—the aquatic flora for example,—will lead to the same conclusion.

ISSN:0008-4026    

DOI:10.1139/b52-033

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

The internal air of maple trunks was found to vary considerably in composition, particularly in decaying trees. In all cases carbon dioxide occurred in much larger, and oxygen in smaller amounts than in the atmosphere. Carbon dioxide content was highest in the summer and lowest in midwinter, oxygen varying reciprocally. Diurnal variations were also noted. Growth of maple rot fungi on malt agar was favored by carbon dioxide in concentrations found in living trees. In several cases, optimum concentrations were of the order of 10%, growth being approximately double that in carbon dioxide-free air. Oxygen had little effect within the range of concentrations occurring in trees. It is concluded that aeration is probably not an important factor in the development of decay, poor aeration tending to be stimulating rather than inhibiting.

ISSN:0008-4026    

DOI:10.1139/b52-034

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

A crystalline antibacterial substance isolated from apple leaves has been identified as phloretin. It has been shown to inhibit the growth of a number of Gram-positive and Gram-negative bacteria. The activity of the compound is bacteriostatic in nature and is shown in concentrations as low as 30 p.p.m. Its antibacterial action may be related to inhibition of the uptake of phosphorus by the bacterial cell.

ISSN:0008-4026    

DOI:10.1139/b52-035

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

It is attempted to clearly distinguish between bogs on the one hand and swamps and marshes on the other. The principal elements and factors are listed in Eastern North America where bogs are frequent. This first paper attempts a general outline of the dynamics of bog vegetation in this region and describes the structures of the communities involved. The biotope is considered the smallest piece in the association mosaic and its physical and biological aspects are emphasized. Two recent systems (Küchler's and Dansereau's) are applied to individualize the most important and widespread synecological units. Further studies involving climatic relationships on a geographical scale and phytosociological measurements at the quadrat level will permit a refocusing of some of the phenomena which are described and interpreted here.

ISSN:0008-4026    

DOI:10.1139/b52-036

出版商:NRC Research Press    

年代:1952

数据来源: NRC