activity (3-GPD). SO myofibers are weakly to moderately active, FOG myofibers moderately to strongly active, and FG myofibers strongly active. Type IIC or intermediate type myofibers (E) are reactive for myosin ATPase after both acid (Fig. 1a) and alkaline (Fig. 1b) preincubation, strongly active in NADH dehydrogease activity (Fig. 1c), and weakly active in 3-GPD activity (Fig.1d). X 130Figs. 2 and 3. Differences in distribution of SO myofibers between the gastrocnemius (Fig. 2) and soleus ( Fig. 3) muscles of Japanese macaques. Myosin ATPase reaction after acid preincubation. SO myofibers are reactive (dark); FOG and FG myofibers unreactive (light). X 65.