The death of Horace Mann, mentioned in the next letter, Dr. Gray felt as a great personal loss, as well as a loss to science. He was a young man of much promise, and he felt on leaving home that, in putting him in charge of the herbarium and of the college classes, he could not have made any arrangement more promising and satisfactory. He had counted much on his future help as assistant, and anticipated that he would become a very valuable aid in carrying on his work, for he had patience, conscientiousness, and steady diligence. Mr. Mann’s lungs were weak, and his health required care, but nothing of immediate danger was feared. But consumption developed rapidly, and he died after a few weeks’ illness. Charles Wright was also working at Cambridge, and took charge of the herbarium and garden during Dr. Gray’s absence. TO CHARLES WRIGHT. HYÈRES, EAST OF TOULON, November 29, 1868. I had yesterday at Marseilles a letter from Mrs. Mann, conveying the sad intelligence of her son’s death. Very sad it is.... My heart bleeds for poor Mrs. Mann, who was wrapped up in Horace, and who feels it as the greatest of disappointments. To me, also, it is a very great disappointment of long-cherished hopes. I expect to find letters at Alexandria when we reach there. We sail from Marseilles a week hence, going meanwhile to see some of this famous shore further east.... CAIRO, December 16, 1868. Thank you heartily for your letter of November 13. I am here learning some subtropical botany, seeing trees growing which you have in Cuba, etc., Parkinsonia, Schinus molle, Carob, etc. Off up the Nile to-morrow.... In brief, I want to retain you permanently as my fidus Achates. You are to have supreme control of the Garden. When I get home we will see what can be done. You will have to cut off Cuba till then, but can work at Flora Cubensis a good deal of the time. As far as my means can go, you shall be made as comfortable as possible.... Arrangements were made to have H. sweep and keep clean the herbarium, and Mrs. L. to scrub when needed. I fear the herbarium may have been left to get dusty and untidy. Please take it in hand; ask L. as to getting H., or some one, to sweep regularly; let no dusty work that can be helped be done in the large herbarium room. Keep coal-ashes dust from the fire from getting in, etc. Spare no expense and pains to keep down dust and dirt.... As to dampness in herbarium, look out according to your judgment. Air occasionally by leaving open doors of cabinets when a good fire is on, or a dry day out. The north corner of the herbarium is the only place that dampness gathers in, except the shelves next the floors. Well, do the best you can. Good-by.... TO JOHN TORREY. ON BOARD THE STEAMER POONAH, MARSEILLES HARBOR, December 5, 1868.