摘要:

In 1940 the catch of cisco in Lesser Slave Lake increased to over a million and a half pounds; it has remained at this high level for eight years, in the last two of which the catch has exceeded three million pounds. The age composition of the catch has decreased from nearly 80% six-year-olds or older to nearly 80% two-year-olds. During the period 1944-1947 the number ofTriaenophoruscysts in the whitefish has decreased from 265 per 100 fish (102.7 per 100 lb.) to 26 per 100 fish (6.8 per 100 lb.). This paper presents the evidence that indicates that this reduction of infestation in the whitefish has been a result of the depleted cisco population.

ISSN:1923-4287    

DOI:10.1139/cjr48d-007

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Paludrine, atebrin, and sulphamerazine neither prevented nor cured infections withLeucocytozoon simondiin ducklings, nor did they have any noticeable effect on the course of the infections. Paludrine failed to cure an established infection ofLeucocytozoon sakharoffiin a crow. The extensive 'tissue stages' of these parasites probably explain the negative results.

ISSN:1923-4287    

DOI:10.1139/cjr48d-008

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The respiration and anaerobic glycolysis of caecal tissue of chickens were measured; the values obtained were similar to the corresponding values for rat intestine.Infection of the caecal mucosa with coccidia (Eimeria tenella) produced no significant change in metabolic rate. Sulphamerazine, which is coccidiostaticin vivo, did not affect the metabolism of tissue strips.

ISSN:1923-4287    

DOI:10.1139/cjr48d-009

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Under certain conditions of injury to the tail of the tadpole ofRana clamitansaccessory tails arise by regeneration. Methods of obtaining these conditions are outlined and the resultant accessory tails are described. Previous literature dealing with the mechanism that initiates the regenerative process in frog tadpoles is discussed and interpreted in the light of evidence gained in studies of accessory tail formation.

ISSN:1923-4287    

DOI:10.1139/cjr48d-010

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The structure of the proventriculus in 115 species of orthopteroid insects (eight orders) is investigated.The Blattodea, Mantodea, and Isoptera have a conical proventriculus, with 6 or 12 longitudinal teeth. There are eight tubular gastric caeca. The Ensifera (Grylloidea and Tettigonioidea) have a globular proventriculus with a tubular neck. In the globular part are six longitudinal folds each bearing a series of appendages and separated from one another by partitions. There are two bulbous gastric caeca. The four families of the Caelifera have a tubular proventriculus. The Acrididae have six longitudinal plates in the proventriculus and six gastric caeca with anterior and posterior projections. The other three families have no plates in the proventriculus. The Tridactylidae have two gastric caeca, the Tetrigidae have six short, conical caeca, and the Cylindrachaetidae have six long, tubular caeca.The Phasmida have a tubular proventriculus with longitudinal, spine-bearing folds and a long flaplike oesophageal valve. In the Grylloblattaria the organ is globular with 12 longitudinal folds in the intima, and two ranks of 12 pyramidal teeth at its posterior end. The Dermaptera have a tubular proventriculus, flared slightly where it joins the crop. Internally there are six longitudinal folds bearing small scalelike projections, and a cushion of bristles at the anterior end of each fold. In the Plecoptera the proventriculus is tubular, with 14 longitudinal, spine-bearing plates on its inner surface. There are seven tubular gastric caeca.A 'phylogenetic tree' demonstrates the relationships of the groups studied, and a systematic key is prepared.

ISSN:1923-4287    

DOI:10.1139/cjr48d-011

出版商:NRC Research Press    

年代:1948

数据来源: NRC