MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



263 



elongated. The development of the tissues varies greatly from the 

 normal. Parenchyma exhibits an accelerated and exaggerated 

 growth in cortical, medullar, and fascicular tracts, which has the 

 result in some instances of increasing the thickness of the petioles. 

 Leaves of this group are of comparatively brief duration. 



Etiolation of Leaves Arising from Aerial Stems. — The remaining 

 species included in the experimental tests embraces a number of forms 

 of dicotyledonous and monocotyledonous plants, some of which make 

 a distinct aerial stem, and which may bear either foliar or bract-like 

 leaves. The following species may be included in this group : 

 Asparagus officinalis (p. 73), Aster divaricates (p. 78), Cyfripedium 



A B C 



Fig. 169. Partial transverse sections of leaves of Vicia Faba. A, normal; B, 

 leaf etiolated by " partial etiolation," a portion of the shoot being exposed to light; 

 C, fully etiolated leaf; ep. s., ventral epidermis;/, palisade tissue; /, spongy paren- 

 chyma; e/>. /., dorsal epidermis. After Teodoresco. 



montanum (p. loi). Delphinium exaltatuni (p. 102), Galium circae- 

 zans (p. 106), Hydrastis Canadensis (p. 117), Iponiisa Batatas (p. 

 120), Lysimachia terrcstris (p. 123), Opuntia Opimtia (p. 130), 

 Phaseolus. sp. (p. 147), Phytolacca Decandra (p. 149), Podophyllum 

 peltatum (p. 150), Saururus ccrnuus (p. 179), Vagnera stellata (p. 

 185), Viola, rostrata (p. 187), and Smilax Beyrichii {^. 199). Aside 

 from the special relations entailed by the climbing habit, the leaves 

 of species exhibiting this capacity should also be brought under the 

 same considerations as the above named. Special reactions were 



