Fig. 4
From: Comparative and functional analysis of the digital mucus glands and secretions of tree frogs
ATR-IR spectra of frog mucus. a Comparison of ventral digital (solid line) and abdominal (dotted line; absorbance scaled by ×3) mucus in Hyla cinerea. Vibrational peaks attributed to amide, N-H stretch, aromatic C-H stretch, and aliphatic C-H stretches were obtained. b Comparison of abdominal mucus spectra of the arboreal frog species H. cinerea (black) and Osteopilus septentrionalis (red; absorbance scaled by ×0.1) as well as the terrestrial species Pyxicephalus adspersus (blue; absorbance scaled by ×0.5). The spectra are offset along the ordinate axis in steps of 0.002 for clarity