Con lo dicho hasta ahora, pensaríamos que la explicación de la dispersión durante el período glaciar estaba terminada. Pues no, sigue …….   648 As the warmth returned, the arctic forms would retreat northward, closely followed up in their retreat by the productions of the more temperate regions. And as the snow melted from the bases of the mountains, the arctic forms would seize on the cleared and thawed ground, always ascending, as the warmth increased and the snow still…