LECT. XI.] ANATOMY OF LEAVES. 605 



most all the monocotyledons, in the Grasses, and 

 in every plant the leaves of which have parallel 

 costae, the meshes are nearly irregular parallelo- 

 grams ; but, in forming these, the vessels some- 

 times run in straight lines, as in common Meadow 

 grass, Poa trivialis (45.) ; sometimes in slightly un- 

 dulated lines, as in the White Lily, Liliurn candi- 

 dum (44.); and sometimes zig-zag, as in Indian 

 Corn, Zea Mays (fig. 14, Plate 10). In some of the 

 fleshy leaves they are nearly regular hexagons, 

 as on the upper disk of Hoya carnosa (fig. 4, 

 Plate 10), and on both surfaces of the leaves of 

 Aloe verrucosa (43.) : but, in the majority of di- 

 cotyledons, they assume very irregular figures -j~. 



WK 



" qu'elle presente viennent de la forme des cellules dont elle 

 ** faisait partie." " Les parois cellulaires restant attachees a 

 " l'piderme, y dessinent de petits compartimens dont la forme 

 " indique celle du tissu cellulaire lui-meme. Tantot ce sont des 

 " parallelogrammes plus ou moins reguliers, tantot des hex- 

 " agones, tantot des polygones divers, dont les cotes sont on- 

 dules.' 1 Elem. de Phys. veg. 1 partie, p. 36. 



f This irregularity is well exemplified in common Sorrel, 

 Rumex acetosa. In Plate 10, fig. 9 represents a minute portion 



