Fig. 5. Histogram showing heart (A) and lung (B) dry masses of exsanguinated deer mice at two different altitudes and acclimated to either warm (open columns) or cold (filled columns) temperatures. Within a single column color, letters that are different from each other indicate statistically significant differences. Asterisks indicate statistically significant differences between temperatures. Values are means +1 S.E.M. (N as in text).