104 PRACTICAL BOTANY. 



References for Reading. Bennett and Murray's " Cryptogamic 

 Botany," pp. 260-263; Vines' "Text-Book of Botany," p. 246; Goe- 

 bel's " Classification of Plants," p. 49 ; Carpenter's " The Microscope," 

 p. 478 ; Campbell's " Structural and Systematic Botany," p. 33. 



The Characeae or Stone worts. The Characese differ so 

 much from all the plants below them and from all those 

 above them that it is difficult to deter- 

 mine their position. Their place is far 

 from settled, and writers of the highest 

 authority differ in opinion in regard to 

 them. They rank decidedly higher in 

 complexity of structure than any of the 

 plants thus far considered. A large num- 

 ber of species is found in the various parts 

 of the world. Some occur in almost every 

 locality. The species are all comprised in 

 two genera, Chara and Nitella, which may 

 in general be distinguished by the fact 

 that a transverse section of the stem of 

 Nitella is like the section of a single hol- 

 low tube; a similar section of Chara is 

 like the section of a tube surrounded by a 

 number of smaller tubes. A surface view 

 of the portion of a stem of Nitella between 

 two nodes shows a single large cell ; a similar surface view 

 of Chara shows a number of cortical cells overlying the 

 large central cell. A few species of Chara do not have 

 the cortical cells. The leaflets are single celled in Chara ; 

 usually more than one celled in Nitella. The plants may 

 be found in sluggish fresh-water streams and in ponds. 

 They vary in color from a light to a very dark green. 

 They grow attached by rootlets to the mud on the bot- 

 tom. Some species grow only partly submerged ; others 

 are wholly covered by the water. The latter may be 

 looked for by raking the bottom of ponds in the shallow 



