Keywords: PSM V51 D664 Changes in frog nerve cell due to electrical stimulation.png Changes in frog nerve cell due to electrical stimulation http //www archive org/details/appletonspopular51youmrich Popular Science Monthly Volume 51 1897 author PD-old Extracted image from book to grayscale cropped whitespace ineuw http //www archive org/details/appletonspopular51youmrich Popular Science Monthly Volume 51 Popular Science Monthly illustrations/Volume 51 Anatomical plates and drawings of the human nervous system |