vi.] STONEWORTS. 51 



d. Their growth at the base, the terminal leaf-cell 

 soon attaining its full size and not dividing. 



e. The development of branches; from nodal cells 

 in leaf-axils, which take on the character of ter- 

 minal cells. 



d. The spore-fruits. 



Examine fresh, under a low power. 



a. Made up externally of five twisted cells, bearing 

 at their apices five smaller, not twisted cells. 



/?. Cut sections from imbedded specimens, and 

 examine with a high power: make out the 

 large central nucleated cell; the fatty and 

 starchy matters contained in it; stain with 

 iodine. 



y. Press out chromic acid specimens in glycerine ; 

 make out the above points (d. a, /3). 



8. Examine chromic acid specimens for young 

 spore-fruits, and press them out in glycerine : 

 make out in the youngest the five roundish 

 cells surrounding a central one; then in older 

 specimens the elongation, and twisting of the 

 external cells, and the separation of their apices 

 as five distinct cells. 



e. The antheridia. 



a. Examine, with a low power, a ripe (orange- 

 coloured) one. 



a. Make out its external dentated cells. 

 /?. Tease out a ripe antheridium in water; and 

 examine with a high power; note the flat, 

 dentated, nucleated external cells ; the cylin- 

 drical cell (manubrium) springing perpendicu- 



42 



