Artificial flowers are used for scientific as well as for purposes. They are made from a variety of 57 such as wax and glass, so skillfully that they can scarcely be distinguished from 58 flowers. In making such models, painstaking skill and artistry are called for, as well as thorough knowledge of plant structure. The 59 of glass flowers in the Botanical Museum of Harvard University is the most 60 in North America and is widely known throughout the scientific world. In all, there are several thousand models in colored glass, the work of two artist-naturalists, Leopold Blaschka and his son Rudolph.