Jerry, I make reference to Henderson in my descriptive guide to Mark Twain, entries 66 and 266. I have Duckworth and Company as publishers for the 1911 publication of _Mark Twain_. The second entry is actually for Arthur Scott's _Mark Twain: Selected Criticism_. Scott here includes a psychologically probing essay on Twain. Jason G. Horn, Ph.D Gordon College Barnesville, GA 30204