WITHIN six weeks the first of the Spring Races will be rowed over the Charles River course, and it is highly important that more active preparation should be made by our boat-clubs. Replies to the challenges sent by the Secretary of the H. U. B. C. have been received from three amateur clubs of Boston and vicinity. The Union Boat Club will send at least one competitor for the single-scull race on May 11. The Secretary also writes that, in all probability, a four-oar will be entered by the Union to row with our four picked from the University second eight. The boat-club of the Young Men's Christian Association is unable, at its present stage of organization, to accept the challenge, but we understand that this rowing club will be glad to join the regatta if their plans are sufficiently advanced and the necessary arrangements made a few weeks before the race. An entry for the single-scull race has been made by the Newton Boat-Club, but this organization regrets that it cannot take part in the race on May 25. No reply has been received from the Jamaica Plain Club. Although the project of a combination regatta has not met with the encouragement and support from the amateur clubs of Boston and vicinity which was expected, there is a fair prospect of our having two interesting races. The single-sculls will attract no little attention, and the Union and Harvard four-oars ought to make a good race. It is a matter of regret, however, that none of the associations challenged is willing to send a six-oared crew. The race which it was hoped would take place, May 25, between the six of the winning club and the amateur sixes, will be given up, therefore; but that is no reason for neglecting practice for the club races assigned for May 11.