6 Introductory 



not so much as a lichen was to be discovered, even 

 Avith the help of a microscope. 



But this is quite an exceptional state of things, due 

 to the extreme rarity of the rain; and such utterly 

 barren surfaces are not only very few, but very small 

 compared with- the whole extent of the farm-— mere 

 spots, in fact, in the midst of generally luxuriant 

 crops. 



In most cases the so-called deserts are deserts 

 only for want of water; the soil has been carefully 

 made ready, and in the Great Sahara and the deserts 

 of Egypt it is extremely rich, though at present covered 

 with sand. "What it might be, and how easily it might 

 be made to ' blossom like the rose,' we can to some 

 extent guess, when we find that the passing showers, 

 which are all that visit the deserts of Egypt, are 

 sufficient, scanty as they are, to awaken 'the green 

 things on the yellow surface ' ; though we may well 

 wonder how the seeds ' could germinate after months 

 of exposure to the burning sun.' 



And then, again, while it is quite certain that 

 such vegetation as exists in these regions is grown 

 entirely by the natural labourers, there seems also 

 good reason to suppose that man actually does much 

 to hinder their work. 



If, for instance, man and his domestic animals were 

 banished from the Arabian and African deserts, it is 

 believed by Mr. Marsh that many parts of them would 

 soon be covered with forests, and with forests would 

 come rain, to the enormous benefit of the whole region. 

 Acacias of several species are constantly being sown, 

 and they sprout up plentifully around the springs and 

 winter water-courses, while grasses and shrubs grow 



