CHAPTER XVII. 

 VEGETATIVE REPRODUCTION. 



I. Fission and budding. 



301. Fission. — In single-celled plants cell division and 

 reproduction are practically identical, since shortly after divi- 

 sion occurs the two cells so produced separate and lead an 

 independent existence (C, fig. 18). Such a method of repro- 

 duction evidently interferes little with the processes of nutri- 

 tion, which probably are scarcely even suspended during the 

 process of reproduction. 



302. Budding. — A slight variation of the method of fission 

 just described is to be found in those single-celled plants, 

 such as the yeasts, whose growth is so localized as to form 

 upon one side a small enlargement which ultimately attains 

 the size of the parent, with which it is connected by a very 

 narrow neck (fig. 48). Across this neck the partition wall is 

 formed in the usual way. This becomes mucilaginous, ren- 

 dering the adhesion of the daughter cell at this point so weak 

 that it is easily separated from the parent. This method of 

 reproduction is known as budding. 



303. Fragmentation. — In those plants which consist of 

 a row of cells more or less closely united, the breaking up of 

 the filaments into separate pieces, either through externa] 

 force or the death of one of the cells, may produce a number 

 of smaller colonies or of new individuals, each of which may 

 grow to full size. In some of the more looselv organized 

 filament-colonies, such as Nostoc (see • 13, and figs. 1 }, 

 14), there are specialized cells whose function seems to be 



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