MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 233 



normal plantlets, and all are characterized by exfoliating bark in the 

 adult tree. The anatomical details of etiolated forms of this type 

 will be described in a later section of this memoir. It may be said 

 in this place however, that the transpiratory organs inclusive of len- 

 ticels were more sparsely developed than in the normal. 



But two species of woody plants were examined in which the 

 cotyledons served as the main storage organs, and were carried aloft 

 during germination. Glcditsia developed the hypocotyl to a length 

 50 per cent, in excess of the normal, and the first internode of the 

 plumule attained a length of 8 mm. The cotyledons were held in an 

 appressed position, enduring through a period of sixty days, much 

 longer than in the normal, and were thrown off only after their con- 

 tents were completely exhausted. The other species, a Phaseolus, 

 developed a hypocot}^ longer than the normal ; the contents of the 

 cotyledons were entirely transferred, leaving but a small remnant 

 which was cast off with the withered seed leaves. The amount of 

 material thus laid down in the embryonic stem was sufficient to per- 

 mit the growth of the first internode of the plumule to a length of 

 three times the normal, and for the development of a pair of leaves 

 with small laminae and attenuated petioles. The second internode 

 was hindered in its growth by the exhaustion of the food supply. 

 The difference in aspect of this plant and that of the terminal portion 

 of partially etiolated adult stems was most noticeable. 



The root systems of the various seedlings etiolated were incapable 

 of exact comparison with those of control specimens, but in the main 

 it appeared that the total length and general development of the roots 

 of etiolated plants was not so great as in normal specimens. The 

 growth of the root system would depend to a great extent, however, 

 upon the transpiratory functions of the shoot, and as no etiolated 

 shoot excretes more than a third or a half of the usual amount of 

 water vapor, the effect of the lessened use of water would be reflected 

 in a diminished development of the absorbent organs, which, in the 

 greater majority of instances, also have less exacting demands upon 

 them for mechanical rigidit}' as a means of anchorage. 



It is difficult to estimate the value of the various records that 

 have been made of this phase of etiolation, since the results in some 

 instances were obtained by "partial etiolations," and in others the 

 growth of the shoot may have begun before confinement in darkness, 

 and then in still other instances the dark chambers were not abso- 



