PROTOPLASM. 9 



node. These internodes are peculiar. They consist of but a single " cell," 

 and are cylindrical, with closed ends. They are sometimes 5-10 cm. long. 



19. Internode of nitella. — For the study of an internode of nitella, a 

 small one, near the end, or the ends of one of the " leaves " is best suited, 

 since it is more transparent. A small 

 portion of the plant should be placed 

 on the glass slip in water with the 

 cover glass over a tuft of the branches 

 near the growing end. Examined with 

 the microscope the green chlorophyll bodies, which 

 form oval or oblong discs, are seen to be very numer- 

 ous. They lie quite closely side by side and form in 

 perfect 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. 9. 



20. Cyclosis in nitella. — The chlorophyll bodies 



are stationary on the inner surface of the wall, but 



if the microscope be properly focussed 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 move- lg ', ' 



, . Portion of plant nitella. 



ment at the end of an internode the particles are seen 



to glide around the end from one side of the neutral line to the other. So 

 that when conditions are favorable, such as temperature, healthy state of the 

 plant, etc., this gliding of the particles or apparent streaming of the proto- 

 plasm down one side of the " cell," and back upon the other, continues in 

 an uninterrupted rotation, or cyclosis. There are many nuclei in an internode 

 of nitella, and they move also. 



21. Test for protoplasm. — If we treat the plant with a solution of iodine 

 we get the same reaction as in the case of spirogyra and mucor. The proto- 

 plasm becomes yellowish brown. 



22. Protoplasm in one of the higher plants. — We now wish 

 to examine, and test for, protoplasm in one of the higher plants. 



