摘要:

Series of eggs collected at various Canadian Atlantic Coast Hatcheries from 1934 to 1940 were used as the bases for a survey of the embryology of the Atlantic salmon (Salmo salarL.) from fertilization to hatching. Early developmental stages from cleavage to the delineation of the embryonic shield are described. Somite formation commences when the embryonic axis is between 1 and 2 mm. in length, and is complete shortly after closure of the blastopore when 60 somites are evident at an embryonic length of 6 mm. Following this the embryo takes on a progressively more fish-like form until hatching.The temperature of the water during most of the incubation period is relatively constant (0.5 °C. to 1 °C.) and the embryonic length data when plotted over this period fit the requirements for straight-line curves. The variation in the thermal units required to reach the same stage in different series indicates that their validity as criteria for determining comparable stages in embryonic development is doubtful.Periods of greatest mortality in development occur during cleavage and blastoderm formation to the closure of the blastopore and at hatching.

ISSN:1923-4287    

DOI:10.1139/cjr44d-008

出版商:NRC Research Press    

年代:1944

数据来源: NRC

摘要:

Ten species of the Compsothlypidae were dissected and diagrams of the arterial arrangement in the neck and thorax prepared. The basic family arrangement-pattern was found to be characteristic for all of the species studied. The ligamentum aortae was present and somewhat reduced, while the right ligamentum botalli was completely atrophied. The intercostal arteries arose near the base of the coracoid major arteries.

ISSN:1923-4287    

DOI:10.1139/cjr44d-009

出版商:NRC Research Press    

年代:1944

数据来源: NRC