VEGETATIVE REPRODUCTION. 1 87 



an independent existence (C, fig. 10). Such a method of 

 reproduction evidently interferes little with the processes of 

 nutrition, which probably are scarcely even suspended during 

 the process of reproduction. 



261. 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. 29). Across this neck the partition wall 

 is formed in the usual way. This becomes mucilaginous, 

 rendering 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. 



262. 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 external 

 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 loosely organized 

 filament-colonies, such as Nostoc (see T[ 11, and fig.- 6), 

 there are specialized cells whose function seems to be to 

 loosen pieces of definite length, which creep out of the jelly, 

 grow, and thus .produce new colonies. 



The greater size reached by most multicellular plants soon 

 renders impossible the continuance of this method of repro- 

 duction, except among those whose cells are all alike. 

 Should such separation into nearly equal parts occur among 

 more highly specialized plants, it is evident that one portion 

 might easily be left without nutritive organs adapted to its 

 needs. The higher plants, therefore, specialize certain 

 regions or members, where, by division or budding or similar 

 processes, reproductive bodies may be formed. 



