STONEWORTS, OR BASS WEEDS 



249 



egg cases (antheridia and oogonia) but are too complex for 

 study here. 



383. Cyclosis in the stoneworts. The stoneworts are 

 remarkable for the striking movement of the protoplasm in the 

 cells (cyclosis). For the study of the rotation of protoplasm, 

 Nitella, or one of the naked 

 species of Chara, is best 

 suited. A small portion of 

 the plant near the end, or 

 one of the "leaves," may be 

 examined with the microscope. The 

 green chlorophyll bodies, which form 

 oval or oblong discs, are very numerous. 

 They lie quite closely side by side and 

 form in rows along the inner surface of 

 the wall. One peculiar feature of the 

 arrangement of the chlorophyll bodies is 

 that there are two lines, extending from 

 one end of the internode to the other on 

 opposite sides, where the chlorophyll 

 bodies are wanting. These are known 

 as neutral lines. They run parallel with 

 the axis of the internode, or in a more or 

 less spiral manner as shown in fig. 200. 



The chlorophyll bodies are stationary 

 on the inner surface of the wall, but if 

 the microscope is properly focused just 

 beneath this layer we notice a rotary 

 motion of particles in the protoplasm. There are small granules 

 and quite large masses of granular matter which glide slowly 

 along in one direction on a given side of the neutral line. If 

 now we examine the protoplasm on the other side of the neutral 

 line, we see that the movement is in the opposite direction. If 

 we examine this movement at the end of an internode the parti- 

 cles are seen to glide around the end from one side of the neutral 

 line to the other. So that when conditions are favorable, such 



Fig. 199. 

 Portion of plant nitclla. 



