1 0 0 0 OA ウスタビガRhodinia fugax Butlerに就て
The larvae of R. fugax, hatched out of eggs collected in the field, were reared in our laboratory for two generations (1947-'48), to observe their life history and hibernation. A. The life history. The periods of each larval instar, pupae and embryo were not always constant as they were controlled under the conditions of that year. For instance, the period of the larval life is variable in the limit of 77-78 days, the pupa in 108-124 days and the embryo in 160-165 days respectively. The worms reared in the laboratoy were always healthy but not as good as those in the field. Especially, the adults which emerged in the room were almost unable to open their wings enough, and to mate with each other, unless the pupae were sometimes subjected to moist conditions. It is of most interest that the full-grown larva utters a small curious sound whenever the anterior segments of its body are suddenly bended. This is one of characteristics of the species. B. Embryonic hibernation. This species takes pupal estivation for over three months in the autumn as well as embryonic hibernation in the winter months. The type of embryonic hibernation seemed to be ong to the fourth group which is one of the five hibernating proups in insects which were classified by the present author ('46). In general, the eggs of this fourth group are used to show the non-diapause type, passing the winter months with the stage of appendage formation, so-called the half-development stage. Therefore, eggs belonging to this type should hatch in a short period under the incubation of the suitable temperature of 25℃ (ses the author's report of 1946). C. The number of larval segments of insects. In the larva of this species, there will be seen thirteen pairs of small spherical processes of 0.5mm in diameter on each segment along the lateral side of the larva with greenish yellow on the dorsal and with dark green on the ventral. These processes are very beautiful and are of a brilliant light indigo colour. Thus, the presence of these processes proves that there are thirteen segments in the larva (fig. 1) under the naked eye. Now, Tanaka ('28) has once suggested theoretically that the number of segments of the insect larva may be fourteen from the viewpoint of morphological observations on the segments of the silkworm embryo (see fig. 2). Recently, Fukuda (50) found a mutant of the silkworm which has two pairs of spiracles in the last two abdominal segmets in which no spiracles are formed in the normal state, and then he pointed out three segment in this region but they were not clear (see fig. 3) and he insisted that the number of segments in the larva must be fourteen in number, as Tanaka inferred. As the present author has already reported ('26), the number of the segments of insect larva must be decided from the results of morphological observations on the metamorphosis of male genitalia, according to the transplantation or the extirpation of the imaginal disc of the Herold's organ from which a genitalia forms from these experimental results, the author has pointed out that the scaphium (sternite) uncus (tergite) and their extending chitinous plates are respectively transformed from the thirteenth segment. If Fuk da's statment is true, as mentioned above, it will be thought to be theoretically demonstrated by the following discussion. The scaphium and the uncus are transformed from the fourteenth segment, while their extended chitinous plates from the thirteenth. The problem in the connection, however, must be resolved again by more embryological investigations in the future.