[单项选择]以下哪项不属于周围神经系统（）
A. 前角细胞
B. 脊神经根组成的脊神经
C. 运动细胞
D. 视神经
E. 嗅神经

For thousands of years men have been wandering around—for pleasure, for profit, or to satisfy their curiosity. When the only means of transportation were horses, camels and small boats, travelers were already crossing seas and deserts to acquire rare goods or to visit famous places. For the pure joy o{ learning, scholars ventured into distant kingdoms and observed their customs. They tasted the foods; they questioned the wise men about their gods and their history; they sat in fearful admiration on the banks of newly discovered rivers. Then they went back home reflecting upon what they had seen, and perhaps they wrote a book or two about their discoveries. Slowly, nations learned about each other, men met and ideas spread—for better or worse.
There was a time, close to ours, when artists and writers traveled all over Europe and sometimes further to study ancient works of art and to exchange ideas and methods with their foreign colleagues. Poo