January 19th, Mr. Doolittle, of Wisconsin, presented the credentials of Hon. William Marvin as Senator of Florida. Mr. Sumner, seizing the occasion to declare what he thought an essential element of republican government to be observed in Reconstruction, said:-- I have no desire to discuss the question arising on the presentation of these credentials, and I may say that there are reasons for the expression of personal respect toward the gentleman who appears as Senator from Florida. In many particulars--not in all, unhappily--he has done well where he was placed. I say, unhappily not in all particulars; for no person can read his speeches and say that in everything he has done what a governor of one of those States at this time should do. But I have no desire to discuss his case. The Senator has alluded to the actual condition of Florida. I also ask attention to the actual condition of things there, as represented by thoroughly competent witnesses, whose character is vouched by the first citizens of that State. Mr. Sumner here read two communications, mentioning that four fifths of the Legislature were Rebel officers, and setting forth the programme of the Rebel States hostile to Reconstruction, and declaring that the only hope of Union men was in Congress. He then said:-- There, Sir, is testimony direct from Florida. Besides, we have the Constitution which the recent pretended Convention has put forward,--a Constitution which, after recognizing the abolition of Slavery, and therefore the citizenship of those once slaves, proceeds to decree their disfranchisement; and Senators are expected to receive this document as creating a republican form of government,--a Constitution which begins by the denial of equality to nearly one half its citizens! The question is entirely changed since the abolition of Slavery, for all are now citizens; and I insist, and at a proper time shall argue the question, that no State, where the government has lapsed, can be recognized as republican in form, while disfranchising any considerable portion of its citizens, especially if it founds any right, immunity, or privilege on color. The credentials were laid on the table, and never afterwards considered. IMPANELLING OF JURIES, AND TRIAL OF JEFFERSON DAVIS. REMARKS IN THE SENATE, ON A BILL REMOVING CERTAIN OBJECTIONS TO JURORS, JANUARY 22, 1866. Mr. Clark, of New Hampshire, called up a bill, reported by the Judiciary Committee, “in relation to the qualifications of jurors and to writs of error in certain cases.” The first section removed the objection to jurors serving in certain cases by reason of having formed or expressed an opinion founded upon common notoriety, public rumor, or statements in public journals. The other section provided a writ of error on questions of law, where the punishment was death. Mr. Sumner remarked:--