But desert in Persia is of many kinds: even the salt desert is not all the same. There are places where the ground is absolutely bare, except for the thick crusts of salt that lie like snowdrifts streaking the surface in every direction. There are also places equally salt where the proximity of a certain amount of useless water produces a larger quantity of plant life than in most parts of the ordinary desert. The ordinary desert is good soil, and wherever water can be brought to it, it is extremely fertile. Generally it has a hard but rather gravelly surface. Sometimes it is flecked with dry brownish shrubs about the size of bedding-out plants, sometimes it is quite bare. There is in parts a good deal of scattered growth, but two plants never touch one another. In the more favourable places shrubs may be found at an average of not more than two yards apart, but, with one exception, I have never seen in the desert plains of central Persia a place away from the hills with sufficient natural growth to modify the colour of the distance. Then there is the sandy desert. Here also, if the sand is scraped away and water brought, the soil is good, but in appearance the sandy desert is the most desolate of all. Absolutely nothing grows on it. It is like the worst kind of salt desert, without the relief of the white patches. Yezd lies in a big stretch of sandy desert. Sometimes the sand may be broken by a large piece of gravelly plain, but such places are generally as bare as the sands themselves, and form no real break in the dull monotony. Of course there are oases; but what is called an oasis is not really very different in character from the desert that surrounds it. It is the same desert artificially cultivated. In the plains the water is brought from a distance, and when it is applied the ground consents to nourish exactly those seeds that have been sown. There are hardly any weeds, no turf, no tangle, no hedges, and no waste green. Every blade in the artificial wheat-field is an isolated unit, that may be pulled up without disturbing its neighbour. Even in the fresher-looking gardens, enclosed and concealed by high mud walls, there is the same meagre, bedded-out appearance on every side. In spite of the possibility of three artificial harvests in the year, one sees at a glance that the very roots will inevitably be annihilated when the water is cut off, and of course this happens pretty frequently. There are no wild trees at all, and those that are reared are very small, and scanty in leafage. Such oases as these go by different names, according to the quantity of water. Those that can support a fairly large population are towns, those that can support a smaller one are villages, those that can only support one or two households are called cultivations, or _mazra’s_. But, however big or however small, they are no interruption to the continuity of the desert.