Changes in the response of silkworm eggs to rotational force during cleavage.

THE eggs of the silkworm (Bombyx mori) have been used in several cases for studying the biological effects of rotational force (Kawaguchi1, Tirelli2). But an interesting change in the response of silkworm eggs to centrifuging which occurs during the early cleavage stages escaped the notice of the authors. The change can be observed both morphologically in the process of pigment formation and physiologically in the rate of oxygen consumption of the eggs. Experiments which revealed the change were carried out in the Department of General Zoology, University of Budapest, in 1946 with eggs of the race Moretiana. The eggs were subjected for one hour to a centrifugal force of about 3,000 g, which caused a visible stratification of their contents. The treatment was applied either in (1) an 'early' stage, centrifuging starting two to three hours after the eggs were laid ; or (2) a 'late' stage, treatment commencing fourteen to sixteen hours after oviposition. The temperature was approximately 26° C. throughout the experiments.