We thank the young friends whose names here follow for pleasant letters received from them: J. G. F., Bettie M. K., Gussie and Nannie M., Edith Norris, Harold K. Palmer, J. E. P., Eleanor D. Olney, Daisy B. Holladay, Nan E. Parrott, Elizabeth P., May E. Waldo, Alma and Estelle, Irene B. D., H. Olina Herring, Carrie L. Walker, Hattie Homer, Florence Halsted, Fay and Fan, Clara E. Longworth, May M. Boyd, Annie G. Barnard, Katie E. G., Alice Butterfield, Mabel P., E. C., James H. Saycock, E. Converse, Abe M. B., P. C. Brittain, L. H. E., May M. Boyd, Marie Clark, Morris Miner, Jo and Flo Overstreet, Roy C. Chambers, May Barton, Bessie Heath, Lawrence E. Horton, Charles R. Van Horn, Albertie G. Russell, S. M. K., Henry H. Townshend, Edith S. C., Blanche Sloat, Sadie Nichols, Jesse L. Pusey, Bessie Lenhart, John N. Force, Madge C. DeW., E. A. Burnham, "Sammy," A. G. K., Fannie B. S., Emily T. H., John R. P., Jr., Tommy Bangs, Florence, Julia McC., Brenda, Harry M. M., Gertie E. Kendall, H. E. H., A. K. E., Anna E. Roelker, M. H. N., "Katie," Etta A. Harper, May S., Tillie Lutz, W. P. Haslett, Charles L., Charlie P. Storrs, Maurice S. S., May, Freddie M., Florence M. Wilcox, Ida R. G., Louis R. E., Bertha, Muriel C. Gere, Ralph M. Fletcher, Bertha B., Ella O., C. H. Pease, Alice W. Brown, Clara L., Arthur F. Hudson, Katie, Thomas H. King, Jr., Mary L. Mayo, O. P., Carrie L. Moulthrop, Alice Dickey, M. Eva T., Daisy W., Marie G. Hinkley, Agatha Montie Duncan, Agnes S. Barker, Samuel S. Watson, Madaleine C. Selby, Hattie A. Taber, Cecelia R. G., Belle Sudduth, Johnnie E. Shaw, Inez B. Fletcher, Eva, Ferrars J., C. P, Hermann Thomas, Annie and Margaret, Edmonia Powers, Alice M. B., D. and A., Anna A. H., Lizzie Kellogg, Louis J. Hall, Charles H. Webster, C. L. Wright, Jr., Merrick R. Baldwin, Eleanor Hobson, Lottie A. D., John Moore, Harold Smith, C. W. F., L. Hazeltine, A. C. Crosby, Mabel L., May J., Grace Plummer, Alice Dodge, Bessie K. S., Ella Bisell, Irma St. John, Irene Lasier, F. L. Waldo, Ruth Morse, Maude G. Barnum, Bertha M. Crane, Aggie Drain, Roy Gray Bevan, John W. Wainwright, Edith, Ella L. Bridges, Bessie Rhodes, Floy G., C. A. G., L. O. C., Mary S. Collar, Pearl Reynolds, Evelyn Auerbach, Mabel E. D., Grace Fleming, Eddie Persinger, Charlie B., Lillie Story, Maude B., Mary M. Steele, Doris Hay, Gussie Moley, Ethel W. F., Arthur, Mary Springer, Marion M. Tooker, Mary F. K., Lizzie E. Crowell, Josie W. Pennypacker, Bertie Barse, Nellie B., J. W. L., Maude Cullen, Daisy C. Baker, Esther S. Barnard, Blanche M. C., Aurelia M. Snider, Howard E. T., Bacon, Hildegarde G., Kittie L. Norris, Nellie L. Howes, Leverette Early, Virginia Beall, Henry W. Bellows, Bissell Currie, Violet Quinn, Mamie Sage, Belle C. Hill, Alvah and Arden Rockwood, Lillian Miln, Adele Yates, Lillie S. E., Ollie C., Maggie Wispert. [Illustration: The Agassiz Association. SIXTY-THIRD REPORT.] A COURSE OF OBSERVATIONS ON TREES.