Der Einfluß der Temperatur auf die Giftwirkung des DDT bei Honigbienen (Apis mellifica L.)

Summary The action of DDT on honey-bees depends to a high extent on the temperature (see graph). At 36°C (breeding temperature) DDT has a far weaker insecticidal action than at 20°C (laboratory temperature). This shows that the insecticidal properties of DDT diminish with the raise of temperature.This resistance to DDT at higher temperature is most propitious for bee-keeping and also explains the fact why in agricultural practice there has been no corroborated case of poisoning of bees, though in laboratory tests DDT avered itself to be toxic to bees.     

Utilization of ascorbic acid during post-embryonic development of chick skeletal muscle

Summary Ascorbic acid is utilized during the post-embryonic differentiation of skeletal muscle fibres in chick. While the fibres lose their heterogeneity with regard to ascorbic acid, they continue to exhibit differences in their metabolic rates in terms of the succinate dehydrogenase activity throughout life.The investigations were carried out at the Department of Zoology, Panjab University, Chandigarh. We thank ProfessorG. P. Sharma, Head of the Department, for providing the necessary loboratory facilities.     

Phagocytose des liposomes par les macrophages péritonéaux de souris

Summary Uptake of¹⁴C-cholesterol or³H-cholesterol labelled liposomes, stimulation of¹⁴C-glucose oxidation, as well as ultrastructural and autoradiographical experiments have shown that liposomes are phagocytized by mouse peritoneal macrophages. Further results have shown that degradation of liposomes was not complete 2 h after uptake.