ii8 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



Fig. 

 leaf. 



Starch was lacking from the etiolated 

 petioles except in the guard cells of the 

 stomata. The fibrovascular tissues were 

 fairly normal in their general development 

 and structure, and the stems were approx- 

 imately of the same degree of rigidity as 

 the normal. The epidermal cells of the 

 etiolated stems were slightly elongated. 

 The hairs borne on etiolated stems were not 

 more than one fourth of the length of the 

 normal. Similar differences are to be found 

 on the leaves. The stomata of both the 

 laminae and the stems were slightly open 

 when examined in water and appeared to 

 be functional. No rhythm in growth could 

 be detected from an examination of the aux- 

 73. lAdrasfis. Normal anometric measurements. (See Fig. 74.) 



10 



mm- 



10 



mm 



10 



mni- 



24 68 10 12 246 8 



A.M. P.M. 



Fig. 74. Curve of growth of stem of Hydrastis during three dajs in dark room 

 at a temperature constant between 22 and 24° C. 



