MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 267 



etiolated leaves, but no distinct individual pericycle could be made 

 out as in hellebore (p. 28). I^agus developed leaves in darkness 

 which were of briefer duration than normal organs, and in which 

 the petioles and laminae were of the ordinary proportions but much 

 smaller than in the normal. The laminae were extended and were 

 held in positions approximately normal. The awakening of the buds 

 of this plant have been found by Jost and myself to be influenced in 

 a ver}^ important manner by illumination. 



A comparison of the data obtained by the etiolation of leaves 

 borne on aerial stems leads to the following general considerations. 

 Leaves of woody, hardy or perennial stems did not attain normal 

 dimensions in any instance, although wholly unfolded and extended 

 in a normal manner in some species. In no instance did the petioles 

 undergo an excessive elongation. On the other hand, leaves arising 

 from tender herbaceous stems, which were produced from under- 

 ground members in darkness generally showed an exaggerated elon- 

 gation of the petiole, if a distinct petiole were present, and in a few 

 instances, a sessile leaf produced a petiolar stalk by the attenuation 

 of the basal portion. Satirurus, Smilax and Phytolacca are exam- 

 ples of forms in which the petioles behaved much like those of 

 woody plants in not making an excessive growth, while Galiu7n and 

 Lyshnachia aie to be cited as furnishing sessile leaves which failed 

 to develop a distinct stalk in darkness. Vagnera produced etiolated 

 leaves shorter and narrower than the normal, in contrast to the other 

 monocotyledonous species, including Cotx, Zea and Cypripedmm^ in 

 which the laminar portions of the leaves were elongated to dimen- 

 sions at least as great as the normal, and in excess of the normal in 

 some instances. An inspection of the data at hand does not afford 

 any means by which safe generalizations may be made as to the 

 behavior of all leaves in darkness. The general habit of the plant, 

 the availability of the food-reserve, the morphological character of 

 the axis, and of the leaves, may play a part in the determination of 

 the reactions, but so far the exact influence of each of these factors 

 has eluded analysis. 



It may be said however that the growth and development of foliar 

 organs is similar to that of stems in the fact that the multiplication 

 and growth of the parenchymatous elements, particularly in the 

 stelar tracts is greater than in the normal, and is not accompanied by 

 the customary morphological differentiation, the failure to achieve 



