On atavism the Machine can have no mercy.

对于返祖现象，大机器绝不会有所怜悯的。

In other words, metamorphosis in mole salamanders is an atavism.

换句话说，鼹鼠蝾螈的变形是返祖。

The atavism passed and he walked the room still, stopping from time to time to look at the telegram.

返祖现象过去了， 他仍然在房间里走着， 不时停下来看看电报。

If for any reason this does not happen, the ancestral feature may not disappear, leading to an atavism.

如果因为某个原因这种现象没有发生，这种祖先的特征可能不会消失，产生返祖。