52 



CELLULAR TISSUE. 



Hieracium sabaudum, Eupatorium verticillatum, Platanus occidentalis, Corylus Avcllana, 

 Claytonia linoides, Escallonia spec, Aralia racemosa, Ferula tingitana. A numerous group 

 of pores is to be found at like points in Tommasinia verticillaris, Archangelica officinalis, 

 Smyrnium perfoliatum, Heracleum flavescens, Eryngium planum, and other Umbelli- 

 fent; Cerastium glabratum, Geum agrimonioides, Arcmonia, Potentilla Thuringiaca, and 



Fig. 19. — Tropaeolum Lobbianuin ; upper surface of leaf. A (150) epidermis, from the maro^in, over 

 the end of a strong vascular bundle, with three large water-pores ; s air-pore. £, C perjjendicular 

 section through w.iter-pores and their immediate vicinity (250). In C some of the cells surrounding 

 the wide resjiiratory cavity have grown out into \av^e papillx- rising into the cavity. 



other species; Alchemilla vulgaris, Ranunculus lanuginosus, and other species; Physos- 

 tegia virginica, Lycopus exaltatus, Hieracium Pilosella, denticulatum (apex of leaf), 

 Rudbeckia speciosa, Senecio vulgaris, and other Compositse ; Valeriana Phu., Brassica 

 spec, &c In the examples given, the upper side of the leaf has air-pores also. Galium 



