DIFFUSION OF IODIDE INTO AND OUT OF THE VOLUNTARY MUSCLES OF THE FROG

¹ The Department of Physiology, University of Edinburgh

1. Observations on the diffusion of iodide into the muscle when immersed in a Ringer's solution containing sodium iodide shows that in the case of fresh muscle only about one-third of its muscle water seems to be involved in the diffusion process, the rest appearing to be shut off by membranes impermeable to iodide. In muscle in heat rigor, however, iodide can diffuse through nearly the whole of its muscle water.

2. The diffusion constants of iodide through (a) fresh muscle of frog previously soaked in Ringer solution containing sodium iodide, and (b) muscle in heat rigor similarly treated, are determined and found to be 1·2 x 10^-4 and 8·5 x 10^-4 respectively. These values indicate that the surface through which diffusion occurs in the case of muscle in rigor is rather less than three times the surface through which iodide can diffuse in fresh muscle. These results support the direct estimations mentioned above.

3. Diffusion constant of iodide through an agar jelly was found to be about 9 x 10^-4.

I am obliged to Dr. P. Eggleton for his continual help and advice in the conduct of this work.

The expenses of this research were defrayed by a grant from the Moray Endowment Fund.