摘要:

Morphometric measurements and counts were made on representative samples of 78 lake whiteflshCoregonus clupeaformis, 77 ciscoesLeucichthys artediand 8 round whitefishProsopium cylindraceumfrom Great Bear Lake, N.W.T. The amount of variability found within this homogeneous population of whitefish casts doubt on the validity of some of the species of whitefish which have been described from this region. The same can be said of the ciscoes.

ISSN:0706-652X    

DOI:10.1139/f53-002

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Sixteen bullheads (Ameiurus nebulosus) and three speckled trout (Salvelinus fontinalis) were kept in complete starvation for periods of time varying from one to two months and seven to ten days respectively. They were then examined, by culture methods, for the presence of bacteria in the intestine. Fifteen bullheads and the three trout did not yield bacteria. A Pseudomonad was obtained, in small numbers, from the intestine of one bullhead. Three bullheads and two trout examined two hours after the last feeding yielded intestinal bacteria in large numbers. In non-feeding fish, bacteria are usually absent from the intestine.

ISSN:0706-652X    

DOI:10.1139/f53-003

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Irregularities occurring in the microbiological assay of herring (Clupea pallasi) materials for vitamin B12(cobalamin) are described and the probable reasons for the differences discussed. With the employment of aLactobacillus leichmanniiassay procedure and conditions under which vitamin B12(cyano-cobalamin) and vitamin B13a(hydroxo-cobalamin) caused identical growth response, it was found that normal commercial flame-dried herring meals had about the same total cobalamin content as specially prepared meals dried at 38° to 43.5 °C. Chromatographic separation, elution and assay of the cobalamins in herring-meal samples indicated that substantially all of the activity found by direct assays of the meals was due to the vitamin itself. Hexane extraction had little effect on the cobalamin content, but heating the meals reduced it.

ISSN:0706-652X    

DOI:10.1139/f53-004

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

When hydroxylamine was incorporated into muscle of halibut, lingcod and coho salmon in concentrations varying from 24 to 240 μg. per gm. (24 to 240 parts per million) it caused a much more marked delay in the rate of bacterial spoilage of samples stored at. 0 °C., and in one instance at 25 °C., than did 200 μg. per gm. of sodium nitrite. From 5 to 50 μg. of hydroxylamine per ml. of nutrient broth either partially or entirely inhibited the growth of ten species of fish spoilage bacteria at 25 °C. and pH 5.9 to 7.5. Somewhat similar results were obtained with a culture of a food poisoning strain ofStaphylococcus aureusand the strict anaerobeClostridium botulinum, except that these organisms were in general less sensitive and that most effective inhibition was obtained at pH 5.9.

ISSN:0706-652X    

DOI:10.1139/f53-005

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f53-006

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Micronereis nanaimoensissp. n. is described from the region of Nanaimo, British Columbia. The definition ofMicronereisis slightly emended to include the species. It differs from its only congener,M.variegataClaparède of Europe, in being much larger, in possessing palps, in having more varied setae and different specialized crotchets in the males, and in colour. Swarming, pairing and egg-laying occur from late March to the end of May. The eggs are moulded by the female into masses covered by jelly, which are deposited on leaves ofZostera,Ulva, or other seaweeds, near low-tide mark, and are accompanied by her in the jelly until the larvae become free-swimming. In the laboratory, larvae left the egg-mass after 10–16 days, in cold water. Larval development up to the three-segmented stage is illustrated, and supports the inclusion ofMicronereisin Nereidae.

ISSN:0706-652X    

DOI:10.1139/f53-007

出版商:NRC Research Press    

年代:1953

数据来源: NRC