On receiving a photograph from Charles Darwin, the American botanist Asa Gray wrote on 11 July 1864: 'the venerable beard gives the look of your having suffered, and … of having grown older'. Because of poor health, Because of poor health, Darwin corresponded little during the first three months of 1864, dictating nearly all his letters and having scientific papers read to him. In March, his health improved; he consulted William Jenner, physician to Queen Victoria, who prescribed radically different treatment to the five physicians Darwin had consulted in 1863. Darwin exclaimed to his close friend, the botanist Joseph Dalton Hooker: 'Hurrah! I have been 52 hours without vomiting!!'. He continued his hybridising experiments and finished a couple of botanical papers, resuming work on the manuscript of Variation, the long-awaited sequel to Origin.