92 Conditions of the Growth of Plants. 



fact, yet as the Arabs from whom the mummies are usually 

 obtained, are in the habit of previously unrolling them in 

 search of coins, it is not always certain that the seeds which 

 have sprouted were really at first enclosed with the body. 



CONDITIONS OF THE GROWTH OF PLANTS. 



Every distinct tribe of plants flourishes naturally under 

 peculiar conditions. Some prefer a warm atmosphere, some 

 a cool one ; some luxuriate only in moisture, and others in dry 

 situations alone ; some require the brightest light, and some only 

 grow in darkness. There are some plants which are very 

 deficient in the power of adapting themselves to slight changes 

 in these conditions, and are accordingly restricted to cer- 

 tain localities, which are favorable to their growth, and are 

 hence considered rare plants. For example, there are certain 

 species which require in the moisture of the air which sur- 

 rounds them, a portion of salt, and these abound only near the 

 sea-shore. But if works for the manufacture of salt are es- 

 tablished, even more than one hundred miles inland, in the 

 neighborhood of these they will spring up, their seeds having 

 been conveyed by the wind or by birds, which have spread 

 tfiem over the whole surface of the ground, but finding only 

 in that spot trie conditions required for their development. On 

 the other hand, many plants can grow in almost any situation 

 and can adapt themselves to a great variety of circumstances 

 often exhibiting under the influence of these, evident changes 

 of form and quality. For example, the Potato, growing in 

 its native tropical climate, does not require for its young shoots 

 that store of nourishment which, in temperate regions, is provided 

 in its fleshy tubers, and thus its edible portion is there ex- 

 tremely small, since the warmth and moisture constantly sup- 

 plied to it, develope the growing parts without such assistance. 

 But when transplanted to a colder clime, and to a richer soil, 

 that nourishing matter is greatly increased, and becomes one 

 of the most important articles of food to man. If it were not 



