346 . Wilhrand and Ritsen*s 



which the order, tribe, or family, either is found exclusively, 

 or more particularly ; or to which they might be transferred 

 by man with the greatest probability of success. Thus the 

 Zamiae, or palm ferns (Jig. 103. 7i\ which are found between 

 20° and 30° N. L. will be found, or might live, in the same 

 parallel (n op q) in both hemispheres, but not at an elevation 

 exceeding 3000 ft., even in the torrid zone. In other words, 

 the geographical range of that order is between 20° and 25** 

 N. and S. L., and its range in regard to elevation in this zone 

 is under 3000 ft. The disadvantage of this pictorial plan is, 

 that it does not indicate to what extent Zamia is found in its 

 peculiar latitude in either hemisphere, nor, indeed, whether it 

 is found in the southern hemisphere at all. 



The general extension of the vegetable kingdom over the 

 globe is shown on the left-hand half of the picture, and of the 

 animal kingdom on the right-hand half; the inhabitants of the 

 sea are shown on both halves of the flat surface {ieaafh\ 

 representing the ocean. 



All plants and animals inhabit either water, or air, or both ; 

 in the water they are in a lower, in the air in a higher, 

 degree of perfection. " The greatest luxuriance of organic 

 life is in the plains of the torrid zone, at the level of the sea." 

 Hence life fluctuates, according to the climate and the sea- 

 sons, to the line of perpetual snow both in the northern and 

 the southern hemisphere. 



In taking a view of the distribution of vegetables, we find 

 the Acotyledones in all climates ; in the torrid and temperate 

 zones as tree ferns, and at the snow line, on the boundaries of 

 organic existence, as iichenes of diminutive size. Monoco- 

 tyledonous plants are found most frequently, and in greatest 

 luxuriance towards the torrid zone, characterising vegetation 

 at the level of the sea at the equator by palms, bamboos, and; 

 scitaminous or reedy plants. Dicotyledonous plants are more 

 uniformly spread over the whole surface of the earth; but stilV| 

 herbaceous plants are prevalent towards the snow line, and 

 arboreous ones in warmer countries. All marine plants are 

 Acotyledones, and among these the jP^ci and [/Ivae are the 

 most generally diffused. They extend from the equator to 

 the region of perpetual ice, but grow principally in the seas 

 of warmer climates. The acotyledonous plants which come 

 nearest to the monocotyledonous are the genera Zemna, Cer- 

 atophyllum, Jkfyriophyllum, and Chara, which form the na- 

 tural order Naiades ; these are common inhabitants of fresh 

 water in the temperate zone. 



Of all monocotyledonous plants, and even of all flowering 

 plants, the grasses are the most abundant, the most universally 



