In the year B.C. 331 an epidemic broke out in Rome which was supposed to proceed from corrupt air, but it was observed that the principal patricians only were the victims. Their deaths, however, were attributed to infection, for poisoning was then scarcely known in Rome nor was there a law for its punishment. In the general grief, a female slave presented herself to the edile curule Q. Fabius and accused more than twenty Roman ladies of poisoning: designing specially Cornelia, a lady of an illustrious family of that name, and Sergia, another patrician lady. It is recorded that as many as three hundred and sixty-six ladies were similarly accused; but Cornelia and Sergia were detected in compounding their fatal potions. "When led before the popular assembly they maintained their preparations were harmless remedies. The slave, seeing herself accused as a false witness, asked that the ladies should be required to swallow their own potions; which they did, and by so doing avoided a more shameful death." Later, there were, doubtless, many, both men and women of the baser sort, who professed to practise alchemy, and had dealings in the black arts, who for suitable consideration would procure poison for criminal purposes. In mediæval times a law was passed in Italy rendering the apothecary, who knowingly sold poison for criminal purposes, liable to a heavy penalty, and yet secret poisoning was practised to a very large extent; and there were probably many like the poor apothecary of Mantua in _Romeo and Juliet_, who, in response to Romeo's demand for poison, replied, "My poverty and not my will consents." From the fifteenth to the seventeenth century two great criminal schools arose in Venice and Italy.