196- 



that's it ; 



upon their under surfaces, 18 ; it 

 here also throws off superfluous 

 water, and becomes a different 

 kind of fluid from what it was 

 when ascending. It now consti- 

 tutes the nu- 

 tritious fluid of 

 the plant, and 

 descends from 

 the leaves, 

 through a 

 series of vessels 

 in the bark, 1 

 and then is 

 deposited so 

 as to form new 

 wood, bark, 

 and other 

 parts of the plant. 



The lowest tribes of vegetables 

 are not only minute, but very 

 simple in their structure. The 

 blue bread-mouldy 1, when exa- 



550. 



mined by the microscope, is found 

 to consist of a number of upright 

 stalks, surmounted by spherical 

 balls. When a cut apple is 

 allowed to remain in a damp 

 situation for a few days, the 

 surface becomes covered with 

 mould of a similar character. The 

 moulds are minute fungi, and the 

 round heads contain innumerable 

 seeds, which, when the plant 

 reaches maturity, are scattered 

 9 



by the bursting of their recep- 

 tacles, and floating through the 

 atmosphere fall upon other sub- 

 stances, where, if they find a 

 congenial element, they give rise 

 to fresh mouldiness. 



The gray lichens, 13, which 

 so abundantly encrust rocks and 

 stones, are also simple vegetables, 



552. 



produced from a small seed, which 

 fixing itself on the flinty rock, by 

 means of a tough mucilaginous 

 juice, becomes the centre from 

 whence others radiate, until a 

 large patch is produced. Mosses, 

 4, and ferns, 6, are vegetables of 



more complicated structure, and 

 hence we ascend to herbs and 

 shrubs, the towering palm, 562 , 



