CHAPTER X 



THE PEEPETUATION OF THE RACE 



In order to perpetuate the race, plants, like animals, 

 multiply and replenish the earth. This fact, obvious 

 enough to the observer, is one upon which we have 

 remarked in several places, and we have described both 

 asexual and sexual modes of propagation. If it has not 

 been stated in so many words, it has at least been 

 implied that reproduction is primarily the result of 

 growth. To what has already been written on the 

 subject, we have now to add a few notes — first, on what 

 is termed " vegetative reproduction " ; second, on modes 

 of pollination; and, third, on methods of seed dispersal 

 leading to more or less successful colonization of new 

 territory. 



Vegetative reproduction in unicellular plants takes 

 place by repeated divisions, as in the Bacteria, a method 

 of propagation equally as common in unicellular animals. 

 In the aquatic Algse of the multicellular types, pieces of 

 a plant may break away and develop into separate indi- 

 viduals identical with the parent plant, or they may 

 produce ciliated zoospores, which eventually come to 

 rest, withdraw their cilia, and give rise to a plant form 

 similar to that which produced them. No operation 

 of sex is involved in the production of zoospores; they 

 are a mode of vegetative reproduction. But they are 



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