Prostrate from opium wars and divided into spheres of European influence, China was unable to protect her citizens from Occidentals who seduced them to immigrate. Poor, illiterate Chinese peasants—especially at Macao after the British Passenger Act (1855) drove the coolie trade from Hong Kong—were easily duped by foreigners who promised them better lives, often in the gold fields of California, once indentures of four to five years had been satisfied.

The foundations for the barrier had been jackhammered away; the piles of broken concrete were just left alongside the road.

In plants, the ability to recognize self from nonself plays an important role in fertilization, because self-fertilization will result in less diverse offspring than fertilization with pollen from another individual.

Taggings account for the vast majority of graffiti.