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Pulsed ultrasound at 2.25 MHz was delivered by a transducer having an average power output of 1.5 mW to a transplantable mouse lymphosarcoma for 5 min. The transplantability of the tumor was reduced. No change in mitotic index as a result of insonation was noted.

1.The oxygen consumption of Drosophila melanogaster pupae during metamorphosis can be expressed by a U-shaped curve, as stated by earlier authors; that is, the consumption is high at the beginning, then falls off rapidly, and from the middle of the pupal period onwards it rises again till about the original level. 2. The oxygen consumption is strongly inhibited by carbon monoxide in all pupal stages. The inhibition is proportional to the percentage of CO and O2 in the gas mixtures and can be expressed by the formula of Warburg (1927) n/1-n·CO/O2=K The validity of this formula means that in Drosophila pupae the oxidizing enzyme system (Warburg-Keilin system) is saturated during the whole period of metamorphosis. 3. The CO effect decreases markedly at the time when the oxygen uptake begins to rise again (the "turning point" of the respiratory curve). Accordingly the value of K increases at this stage. The bearing of this is discussed. 4. The CO effect on oxygen consumption is sensitive to light and can be counteracted to a certain extent by illumination (the limiting factor being probably the opacity of tissues).

No abstract

Pulsed ultrasound from a Picker Ultrasonoscopy Model 102, with a frequency of 500 Hz and an energy of 2.2 MHz was applied to the amputated left forelimbs of 24 adult newts. Exposure time was 5 min in half of the animals and 10 min in the remainder. The right forelimbs of these newts were also amputated at the same time, at the same anatomical level, and by the same operator as the left forelimbs, but were not exposed to sonication. Regeneration of both forelimbs was compared and found to be generally slower in the ultrasonicated limb. In 75 % there was a definite retardation of growth. The results suggest that the growth of rapidly proliferating embryonic tissue (newt regenerates are formed from embryonic cells in the stump) is inhibited by ultrasonication.