XIV.] STONEWORTS. 437 



2. Hold a bit of fresh stem between two pieces of elder- 

 pith or imbed it in paraffin, and, with a sharp razor, 

 cut thin transverse and longitudinal slices through 

 nodes and internodes. Note the cavity of the large 

 central internodal cell ; the cortical cells, round the 

 internodal cell ; the nodal cells, and the interruption 

 of the central cavity at the nodes. 



3. Examine similar sections in specimens treated with 

 spirit, and also preparations made by teasing or press- 

 ing out in glycerine bits of stem from chromic acid 

 (o - 2 per cent.) preparations: make out in these, 



a. The nodal, internodal, and cortical cells. 



ft. The wall, protoplasmic layer (primordial 

 utricle), nucleus, and vacuole of each cell. 

 (The nucleus will have undergone fragmenta- 

 tion in the older cells.) 



4. Examine sections from the fresh stem to make out 

 the points detailed in B. a. 3. ft. The protoplasm 

 and nucleus are difficult to see. Note the chloro- 

 phyll-granules. (See B. b. y.) 



5. Stain sections of the fresh stem with iodine, and with 

 magenta : note the results. 



b. The leaves. 



Examine fresh and chromic acid specimens. 

 a. The large uncovered terminal cell. 

 ft. Then a series of internodal cells, separated 

 from one another, and covered-in, by nodal 

 cells : the cell-wall, protoplasm, nucleus, and 

 vacuole of each. 



y. The oval chlorophyll-granules, arranged so as 

 to leave an oblique uncoloured band round 



