A Contribution to the Study of Galactic Dimensions.

where irregular and bizarre ganglionic masses exist in the complete absence of myotomes. The reduction in the number of ganglia and spinal nerves following somite removal, and especially an increase following the interpolation of an additional somite, constitute strong experimental support of Lehmann's view that the normal segmentation of spinal ganglia and nerves is determined by the mesodermal metamerism. There is no support of the generally held view that nervous metamerism is intrinsic, at least in the spinal cords of the forms which we have studied. 1 Lehmann, F., Jour. Comp. Neur., 49 (1927). 2 Detwiler, S. R., Jour. Exp. Zool., 54 (1932). 3 Detwiler, S. R., op. cit. Lewis, W., Anat. Rec., 4 (1910). 5 The normal brachial nerves constitute the third, fourth and fifth spinal nerves. 6 Lehmann, F., op. cit.