VIII. EXPLANATION OF PLATES 



All (he figures in plates 1 to 9 were drawn witli the ai<l of a camera liicida, the 

 projection distance being 410 mm. Spencer 2 mm. oil immersion, and 4 mm. dry, 

 objectives, and compensating oculars 5, 10, and 15 were used. 



The following abbreviations are used:— 

 s(j., 'soma' cell, derived from the previous division of the 'stem' (-ell. 

 strp., 'stem' or 'propagation' cells. 



585 



