In Koeppen (2013), an acknowledgement statement allowing reproduction of Fig. 1c was omitted from the figure legend in the published version of the paper.
The full legend should read as:
The spinal cord in Friedreich's ataxia. (a and b) gross specimens; (c) reproduction of Friedreich's drawing of the thoracic spinal cord. (d) immunohistochemistry of myelin basic protein. The photograph of the dorsal aspect of the spinal cord (a) shows reduction of the transverse diameter to 6–7 mm (normal: over 10 mm) and thinning of dorsal roots (solid arrows). Anterior roots (open arrows) are normal. A transverse slice of the thoracic spinal cord (b) reveals an overall reduction in size and gray discoloration of the dorsal and anterolateral columns (white arrows and outlined by interrupted lines). Stippling in Friedreich's (1877) drawing of the thoracic spinal (c) indicates degeneration in the dorsal and posterior anterolateral columns (probably gold chloride stain). A modern immunohistochemical stain of myelin basic protein confirms fiber depletion in the same locations (d). Friedreich (1877) stressed the wedge-like loss of fibers in the anterolateral columns, but did not realize that the imperceptible transition from the base to the tip affected two independent long tracts of the spinal cord, namely, the dorsal spinocerebellar and corticospinal tracts. The arrows in (d) indicate the dorsal nuclei in Clarke's column (see also Fig. 2). Friedreich's drawing (c) did not illustrate the dorsal nuclei though they should have been visible at this magnification [see (d)]. Note that Friedreich (1877) rendered his drawings of the spinal cord with the anterior fissure facing upward. For historical accuracy, this style is retained here. This practice was not universal, and Clarke (1851) drew spinal cord sections in the currently familiar way. The ‘upside-down’ display of the spinal cord in Friedreich's ataxia continued into the early 20th century (Lambrior 1911), and the ‘switch’ may have begun with Mott's (1907) paper. Bars: (a) 10 mm; (b) 5 mm; (d) 1 mm. Fig. 1c was reproduced under license by Copyright Clearance Center on behalf of Springer.