264 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



exhibited by the reduced bract-like leaves which subtend the cladodes 

 oi Asparagus, these organs reaching a greater expansion than on nor- 

 mal specimens. The attenuated fugacious ovoid leaves of Ofuntia 

 were larger on etiolated plants than on the normal green fronds, and 

 were of distinctly longer duration. An interesting comparison with 

 Asparagus is offered b}^ Sinilax. The normal leaf of the latter con- 

 sists of a sheathing hypopodium, bearing a pair of tendrils on the mar- 

 gin about 6 to 8 mm. from the base, and passing into a distinct petiole 

 bearing the extended lamina. Leaves developed during etiolation 

 formed a sheathing hypopodium of a size not less than the normal, 

 the tendrils however, being represented by two minute papillae not 

 more than a millimeter in length. The petiolar portion was entirely 

 lacking, and the lamina was represented by a narrow blade only a 

 fraction of the size of the normal. The basal portions of leaves in 

 general were found to be the least affected of an}^ part of the 

 foliar organs during etiolation. 



The other species of this class fall into two groups, viz. ; the first 

 to include leaves arising on newly formed annual stems grown in 

 darkness, and the second comprehending plants which form leaves 

 from buds on perennial or hardy stems. In the etiolation of a 

 plant of the first group it is clearly necessary that a stem should 

 be developed from the underground member and then the leaves 

 may arise from the internodes, making necessary a much greater 

 morphogenic and physiologic effort than when plants of the second 

 group are awakened in darkness. In the latter instance the buds, 

 which may be more or less numerous, begin to elongate and a leaf 

 may arise from the first internode which on stems of the first kind 

 ordinarily may bear only a bract or some form of a reduced foliar 

 organ. 



Leaves of An'stolochia, and Aster developed excessively elongated 

 petioles in darkness, which with the undeveloped laminae were held 

 in various abnormal attitudes. A tendenc}^ to assume an apogeotropic 

 position, or one more or less appressed to the stem, by the petioles, 

 was noticed in the species included in this group, although Apios 

 among the climbers formed petioles shorter than the normal. The 

 laminae of Aster did not unfold, and remained in a ver}^ primitive con- 

 dition, the leaves having a very brief duration in darkness. Etiolated 

 leaves of Cypripedium were twice the length of normal organs, but 

 were of decreased width, in contrast with the leaves of Vagnera 



