The domestic slave-girl rarely has issue. This results partly from the malignant unchastity of the race, the women being so to speak in common; and on the same principle we witness the decline and extinction of wild tribes that come in contact with civilized nations. The chief social cause is that the ‘captive’ has no interest in becoming a mother; she will tell you so in the Brazil as in Zanzibar; her progeny by another slave may be sold away from her at any moment, and she obviates the pains and penalties of maternity by the easy process of procuring abortion. The wild slaves are brought over in daus which carry from 10 to 500 head. Most of those intended for the Island market are comparatively young: the Portuguese settlements at Mozambique give higher prices for able-bodied adults. Since the last treaty the value has more than trebled; what then cost $10 has now risen to $30 to $35. A small boy fresh from the mainland commands from $7 to $15; a girl under 7 or 8 years old, from $10 to $18. The live cargo pays duty to the Zanzibar and Kilwa custom-houses, as at Zayla, Tajurrah, and the slave-exporting harbours of the Red Sea: the sick and the refuse, however, enter free. About 1835 the import duty varied from $0.50 to $4, according to the port whence the ‘black ivory’ was shipped: some races had such an ill fame that only excessive cheapness found purchasers. Presently $2 and at last $1 were levied upon all, good or had. Of late years (1857) the annual maximum collected was $23,000: this enables us to rate the import at an average of 14,000 to 15,000 per annum, the extreme being 9000 or 18,000. In 1860-61 it rose to 19,000, in 1861-62 it fell to 14,000, and in 1862-63 there was a further declension.[122] The impudence and audacity of the wild slaves almost passes belief. Such is their habit of walking into any open dwelling and carrying off whatever is handy, that no questions are asked about a negro shot or cut down in the act of simple trespass. At night they employ themselves in robbing or smuggling, and at times in firing a house, when they join the crowd and spread the flames for the purpose of plunder. They are armed burglars, and not a few murders are laid at their door. In the plantation they gratify their savage, quarrelsome, and ungovernable tempers, by waging desultory servile wars with neighbouring gangs; hundreds will turn out with knobsticks, stones, and a few muskets, and blaze wildly in the direction of one another: at the first casualty all will run. Some proprietors have had as many as 2000 blacks—not half the number often owned in the Southern United States, and in the Brazil—but at those times the negro was worth only from $3 to $10. They were allowed two days out of the week to fish for themselves, and to work at their own patches of ground.