CHAPTER XLII 



MULTIPLICATION IN PLANTS 



Questions. 1. How can plants that have no seeds be multiplied ? 

 2. What are the different ways in which the number of plants of any 

 kind can be increased? 3. Can plants of any species be multiplied in 

 more than one way ? 4. Is it better for a plant to produce large seeds or 

 small seeds ? 5. What kinds of plants produce most seeds ? 6. Of what 

 use is the fruit to the plant ? 7. From what dangers do young plants 

 need to be protected ? 8. How are young plants protected from different 

 kinds of danger? 



341. Cell division. ,We have seen that living cells often end 

 their existence by dividing, each cell giving rise to two new 

 ones (sect. 48), and that they begin their existence by the divi- 

 sion of a preexisting cell. In one-celled plants and animals cell 

 division is a means of reproduction, since it gives rise to new 

 individuals. In many-celled plants and animals cell division is 

 a factor in growth, since it results in a greater mass of living 

 body. It is also a factor in development, since at certain points 

 it gives rise to new kinds of cells and tissues. Under certain 

 conditions cell division in a many-celled plant or animal may 

 result in the healing of wounds, breaks, or injuries. And, finally, 

 under certain conditions cell division in many-celled plants and 

 animals may give rise to new many-celled individuals. 



Adventitious roots on a begonia leaf or a strawberry stem 

 result from cell division, and the process finally brings about 

 the formation of a new plant. This kind of process is the basis 

 of plant propagation and is of great practical importance. 

 There are many useful plants that bear no seeds ; for example, 

 the banana, the pineapple, the navel orange, and seedless grapes 

 and apples. New growths of these varieties are obtained by 

 setting out pieces of stem so that complete plants at last develop 



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