The cytochochleogram in atoxyl-treated guinea pigs.

The earliest atoxyl induced changes in the cochlea appeared in the upper and medial parts of the 4th coil, whence the changes spread progressively downwards towards the round window, the extent of the changes depending on the amount of atoxyl administered and the duration of the treatment. The inner hair cells were more resistant to the effects of atoxyl than the outer hair cells which were affected first. The sensory cells in the 2nd and 3rd rows appeared more sensitive than the outer hair cells in the first row.