Harvard had so much trouble finding a replacement for Gray that they considered hiring a European, but they found an American and hired George Lincoln Goodale in late 1872. Goodale had a medical degree from Harvard and a solid knowledge of botany. By late June 1873 Goodale had enough experience that Gray was excited to pronounce he had taught his last class. William Gilson Farlow also had a medical degree from Harvard and had studied botany. He became Gray's assistant in 1870 after obtaining his medical degree and then studied in Europe for a few years. He returned to Harvard in 1874 and became a botany professor. Sereno Watson began helping Gray with taxonomy in 1872 and became the herbarium curator. The reorganization of botany at Harvard in the early 1870s was a major accomplishment of Gray's.