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ABSTRACT
Within the larynx of Bufo viridis there are, in addition to the vocal cords, cushions of tissue anterior to the cords and folds posterior to them. These structures were ablated in nine different combinations. Three series of operations were performed: each of the nine operations was further combined with the removal of (1) the sphincter muscle, (2) the hyo-laryngeal muscle, and (3) the sphincter and hyo-laryngeal muscles together. The disturbances resulting from operations in the second series were more severe than those following the first. After removal of both muscles, meagre remnants of the voice were retained in only three cases. The vocal cords play a crucial role in Phonation; surgery affecting them invariably had more profound effects than operations which left the vocal cords intact. Removal of the tissue cushions or posterior folds causes loss of voice only in conjunction with removal of both the sphincter and the hyo-laryngeal muscles. Cushions and folds thus appear to serve a sort of accessory function in Phonation, participating especially in the parts of the call with pulse structure.