ナマズの発生経過

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The present paper deals with the breeding habits and the gross morphological development of the catfish, Parasilurus asotus. In Hirosaki, the breeding season of this fish extends from the beginning to the latter part of June. During this season, some males and females migrate at night in a group from the stream into the rice field, with the purpose of performing the spawning. The fertilized egg is spherical in shape and about 1.5mm. in diameter, with a jelly-like coating og about 1mm. in thickness. The development of the fertilized egg conforms to the typical teleost pattern (Fig. 2). Hatching took place in about 57 hours at the water temperature 23℃ and the larva at this time is about 4mm. long. The rudiments of the maxillary barbels appear as a pair of wen-like elevations of the mandibular arch, when the embryo is about 27 hours old after fertilization. By about 13 hours after this period, these rudiments migrate to the outer edge of the mouth (Fig. 3, A). The rudiments of the temporary and permanent mental barbels are formed as a pair of protuberances from the hyoid arch and "inferior branch" of the mandibular arch, respectively (Fig. 3, B and C). The appearance of the rudiments of the temporary barbels is about 49 hours after the fertilization and that of the permanent is about 54 hours.
社団法人日本動物学会の論文
1956-09-15