73 THE STl'ltY O/-' LH'IXd C 



4. The irregular clearl </ <-nt ntr</in of the bands, and the 

 protoplasmic ridge traversing the middle of each. If these are not 

 well defined the cells are not in a healthy condition. 



5. Globose masses or corpuscles, in the band at intervals. 

 These corpuscles are apparently centers of protoplasm, where 

 starch grains are produced, under proper conditions. The cor- 

 puscles and the connecting protoplasmic ridge are regarded by 

 Schmitz as one continuous "chloro-plastid." 



6. The transparent roundish area at the middle of each cor- 

 puscle, the pyrenoid of Schmitz. 



7. The cell nucleus if present ; its form. It may be more 

 clearly brought out by the application of a little dilute iodine. 



8. If protoplasm can be detected in the cell, except in the 

 chlorophyll bands. 



PREPARATION SECOND: Stain a preparation with iodine, by 

 placing a drop at the edge of the cover glass. 



OBSERVE: 1. The effect on the corpuscles, nucleus and pro- 

 toplasm in various parts of the cell. 



2. That the cell wall remains unstained or slightly colored 

 although the iodine must have passed through it. 



3. The slow action of the iodine on the chlorophyll bands. 

 The cause of this slowness. 



PREPARATION THIRD: Stain as before, using strong iodine in- 

 stead of the dilute solution. 



ORSERVE: 1. Contraction of the whole cell contents in some 

 cases. It is a coagulation of the protoplasm, the water being ex- 

 pelled by the iodine. 



2. The color given to the different parts. 



For the study of cell division, keep the plants in a very cool 

 place over night and bring in to the warm laboratory in the morn- 

 ing. The division will begin in a short time. If the plants are 

 kept constantly in a warm place, the division will usually take place 

 at night. In specimens treated as above directed, 



OBSERVE: 1. The ridge of cellulose being pushed inward from 

 the side walls in some cells. This is a *> /itum in active formation, 

 (by progressive cell division). 



2. The chlorophyll, etc., continuing through the aperture of 

 the partly formed septum. Sketch the above appearance. 



