The influence of the soil often produces changes similar to that of climate. This was shown by the above cited experiments of Nageli with the hawkweeds, and may easily be controlled in other cases. The ground-honeysuckle or _Lotus corniculatus_ grows in Holland partly on the dry and sandy soil of the dunes, and occasionally in meadows. It is small and dense in the first case, with orange and often very darkly colored petals, while it is loose and green in the meadows, with yellower flowers. Numerous analogous cases might be given. On mountain slopes in South Africa, and especially in Natal, a species of composite is found, which has been introduced into culture and is used as a hanging plant. It is called _Othonna crassifolia_ and has fleshy, nearly cylindrical leaves, and exactly mimics some of the crassulaceous species. On dry soil the leaves become shorter and thicker and assume a reddish tinge, the stems remain short and woody and bear their leaves in dense rosettes. On moist and rich garden-soil this aspect becomes [444] changed at once, the stems grow longer and of a deeper green. Intermediates occur, but notwithstanding this the two extremes constitute clearly antagonistic types. The flora of the deserts is known to exhibit a similar divergent type. Or rather two types, one adapted to paucity of water, and the other to a storage of fluid at one season in order to make use of it at other times, as is the case with the cactuses. Limiting ourselves to the alternate group, we observe a rich and dense branching, small and compact leaves and extraordinarily long roots. Here the analogy with the alpine varieties is manifest, and the dryness of the soil evidently affects the plants in a similar way, as do the conditions of life in alpine regions. The question at once comes up as to whether here too we have only instances of partial variability, and whether many of the typical desert-species would lose their peculiar character by cultivation under ordinary conditions. The varieties of _Monardella macrantha_, described by Hall, from the San Jacinto Mountain, Cal., are suggestive of such an intimate analogy with the cases studied by Bonnier, that it seems probable that they might yield similar results, if tested by the same method.