14 



BOTANY. 



[chap. I. 



simplest of multicellular plants belonging to the Algee is 

 the restriction of the reproductive function to certain 

 cells or portions of the individual, the remaining por- 

 tion, usually constituting the greater part of the plant, 

 doing vegetative work only, and frequently living for 

 several years, giving origin each season to a number of 



Fig. 2. A portion of one of the olive-brown seaweeds (Fuciis vesicu- 

 losus) showing division of labour or differentiation of the individual. — 

 F, thallus or vegetative portion ; T, fructification, confined to the tips 

 of the thallus ; L, air-bladders formed on the thallus for the purpose of 

 buoying up the plant on or near the surface of the water. (Natural 

 size.) 



reproductive bodies capable of developing into new in- 

 dividuals. It will be noticed that the above indicated 

 division of labour into localized vegetative and reproduc- 

 tive portions is contemporaneous with the formation of 

 all the larger perennial forms of plant life, which in many 

 instances require half a century or even more to attain 



