摘要:

Tests of 2-(p-aminobenzenesulphonamido)-4, 6-dimethylpyrimidine ('Sulphamezathine') as a prophylactic and curative drug for caecal coccidiosis of chickens have confirmed the previous findings of workers in Great Britain and have shown that the disease can be checked even after intestinal haemorrhage has begun.A related compound, 2-sulphanilamido-4-methylpyrimidine ('Sulfamerazine'), and its soluble sodium salt have been found to have comparable value as curative drugs.This work suggests that these sulphonamides, with partly methylated pyrimidine structures, will prove of value as agents for the control of the disease when used in conjunction with other recognized measures. The relationship between the chemical structure and the coccidiostatic effect requires further investigation.

ISSN:1923-4287    

DOI:10.1139/cjr44d-010

出版商:NRC Research Press    

年代:1944

数据来源: NRC

摘要:

Sixty lakes in central and southern Saskatchewan were investigated during the years 1938 to 1943. Most of these are saline and lie within the aspen parkland. A few freshwater lakes from the adjacent forest zone were included for comparison. Physical and chemical studies included observation of depth, temperature, dissolved oxygen, light penetration, and the mineral constituents of the water. The plankton was sampled with nets and traps, bottom organisms with an Ekman dredge, and the fish with gill nets and seines. In the first two years the survey covered all the main lakes in the southern part of the province. In the last three, more intensive studies were made in selected lakes.Most of the lakes have between 300 and 30,000 p.p.m. of total solids but Little Manitou Lake has 120,000 p.p.m. The salts are mostly sulphates of magnesium or sodium with little chlorides. Seasonal, annual, and long-term variations in salinity are discussed. Most of the lakes are shallow and only those of moderate depth show thermal stratification. High salinity affects the course of circulation. Light penetration is low in the shallow lakes but none is excessively turbid.The phytoplankton, dominated by the blue-green algae, is mostly composed of euryhaline species. Higher aquatic plants are widespread but absent from Little Manitou Lake. Cosmopolitan species of halophytes grow around the saline lakes. Rotifers are abundant withPedaliaandBrachionusdominant in the more saline water. The Entomostraca thrive in all salinities. The brine shrimp,Artemia salina, is found only in Little Manitou Lake. Chironomid larvae, amphipods, and mollusca dominate the bottom fauna. The relation of the quantity of bottom organisms to salinity is discussed.Twenty-six species of fish are found. Several species tolerate a salinity of 15,000 p.p.m. but only the nine-spined stickleback,Pungitius pungitius, occurs in 20,000 p.p.m. The saline lakes produce much game fish and about 5% of the commercial catch of the province. Fish planting and the results of three experiments in fish culture are recorded.These lakes may be classified as saline eutrophic. Salinity is the dominant influence and it is also an expression of the climatic and physiographic factors that were responsible for the formation of the lakes. The saline lakes of Saskatchewan are much like those in the steppes of western Siberia.

ISSN:1923-4287    

DOI:10.1139/cjr44d-011

出版商:NRC Research Press    

年代:1944

数据来源: NRC