Naudin gave many instances where, in addition to the hybrid intermediate in character between the parents, a number were obtained exactly resembling the mother species. In one case where he crossed two thorn apples (Datura stramonium with pollen of D. ceratocaula), the capsule thus fertilized remained very small and produced but few seeds, of which many were imperfect and almost all failed to germinate the next spring. Of about sixty apparently good seeds, only three grew, and from these two plants were grown to maturity. These plants were exactly like the mother plant, but were nevertheless abnormal, because of their unusual height, being nearly twice that of the mother species, and also in dropping all the flowers produced in the lower forks. Such increased vigor and partial sterility were observed by Naudin in all intermediate hybrids of Datura, but in this case the plant resulting from the cross showed no trace of the characters of the father species, and its seeds, when planted the following year, yielded the ordinary form of the mother plant.