...Horace Man of Ohio is to open the course of lectures on slavery to be delivered in Boston the coming winter. Invitations to lecture on the peculiar institution have been extended by the Committee to thirteen slave-holders, most of them United States senators. Two only have accepted the invitation unconditionally, Mr. Toombs of Georgia, and Mr. Hilliard of Alabama; and two others have given replies from which the committee have been led to hope that they will consent to lecture; while but one southern gentlemen, Mr. Wise of Virginia, returned an uncivil answer. "The most novel and attractive feature of the course (says the Tribune) will be the reading of a drama written by Mrs. Harriet Beecher Stowe. It will be read by Mrs. Webb, a colored lady, who has given successfully public dramatic readings in Boston. The plot is founded in part upon the story of Uncle Tom's Cabin, and the title is 'The Christian Slave.'—This drama, we learn, will be publicly read during the winter in this city, and in Philadelphia, Washington, Cincinnati, and elsewhere."