FOUR FIQUEES
The experiments of Gemmill ( '40, '41) demonstrated the ability of rat diaphragm muscle to synthesize glycogen in vitro and the effect of insulin in increasing the rate of this synthesis. The effects of varying experimental conditions on this reaction were studied by Stadie and Zapp ('47). The availability of glucose labeled with carbon-14 made possible a study of the effects of different hormonal states on the amount of glucose metabolized to carbon dioxide (Villee and Hastings, '49). The experiments reported here were underaken to determine, with the aid of C14-labeled glucose, the "kaction of the glycogen formed irt vitro by diaphragm muscle which is derived from the glucose of the incubation medium.
Methods
Male albino rats obtained from Albino Farms, weighing 150-200 gm, were used. They were fasted 24 hours before being used in an experiment. Glucose labeled uniformly with C14 was made photosynthetically in bean leaves by the method described previously (Villee and Hastings, '49).
The animals were killed by a blow on the head, the abdomen was opened, and the diaphragm exposed. Each hemidiaphragm was dissected out, trimmed to remove the central