19 14] 



SNOW— DIAPHRAGMS OF WATER PLANTS 



5" 



F. CONDUCTION 



may 



examination 





Fig. 14. — J uncus eflusus: a few cells from cross-section of stem, showing transition 

 from rounded cells on outer edge of pith to stellate cells nearer the center; Xno. 



■ 



j\ 



s 





( 



> 



y 







/ 



Fig. 15. — J uncus e fits us solutus: longitudinal section of stem showing formation 

 of cross-layers in stellate parenchyma; X35. 





groups of cells adjoining the cross-bundle and the partition walls of 

 the air spaces have their long axes perpendicular to the bundle and 

 the walls respectively. This is an almost universal condition; w r here 



