50 ELEMENTAEY ORGANS OF PLANTS. 



The extent of cell-development in forest-trees and flowering- 

 plants is alone different ; the phenomena themselves are pre- 

 cisely analogous. In forest-trees and flowering-plants, the 

 vegetative cells, as they develop in countless millions, assume 

 distinct organic parts, as root, stem, and leaves, whilst the 

 reproductive cells are seen in the form of beautiful and highly 

 organized flowers. In the bread-mould, all such distinctions 

 vanish, and the organization of the parts is reduced to the 

 utmost degree of simplicity. 



57. Let us pause for a few moments, and reflect on the sim- 

 plicity and beauty of these admirable productions of nature. 

 Think of the Liriodendron tulipifera, or tulip-tree, the pride 

 of the American forests. Its wide-spread and powerful roots, 

 its tall and massive stem, its glorious and far-extended canopy 

 of foliage and flowers — this is the result of centuries of assimi- 

 lation from inorganic matter, of the evolution of countless 

 myriads of cells. Now look at the little bread-mould, which 

 nature constructs from decaying organic matter. A few inter- 

 woven tubular filaments form the root, a single row of verti- 

 cal cells the stem, whilst a solitary terminal cell is the humble 

 representative of the flower. Here, then, we have the whole 

 of the vegetative and reproductive process, seen as it were in 

 miniature beneath the microscope, and brought within the 

 compass of a few short hours. 



58. Yet, though nature has thus simplified her operations, 

 how little do we in reality know about them ! We do not 

 know how the cells of the bread-mould originate, why they 

 develop in this particular form, and why, after a certain num- 

 ber of vegetative cells have been developed, a solitary termi- 



