MERRILL LYNCH <MER> IN TALKS ON CANADA PURCHASES Merrill Lynch and Co Inc is holding talks on acquiring Canadian brokerage firms, a company spokesman told Reuters. He said one of the firms with which Merrill Lynch is negotiating is <Burns Fry Corp> of Toronto, which has already received an offer from Security Pacific Corp's <SPC> 83 pct owned <Hoare Govett Ltd> London-based brokerage unit. The Hoare Govett bid is valued at about 210.4 mln U.S. dlrs. The spokesman said the talks are the result of a change in Ontario securities laws that takes effect June 30. Currently, companies outside the Canadian securities industry are prohibited from owning more than 10 pct of a Canadian broker. On June 30, 1987, foreign brokers will be allowed to own up to 50 pct of Canadian brokers, and the percentage will rise to 100 pct a year later.