MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 7 1 



growth during any two-hour period may be found by taking half the 

 distance of the curve from the base line from a point over the 

 numeral denoting the end of the period. Elongation continued three 

 days later than the plotted record. 



Aristolochia sp. 



Some tubers of Aristolochia brought from Bermuda in 1900 

 were placed in the propagating house after a proper period of rest 

 in February, 1901. As soon as indications of activity were shown 

 two cultures were removed to the dark room. 



The normal stems attained a length of 18 to 25 cm. with in- 

 ternodes 1.5 to 3 cm. long. The laminae of the cordate leaves 

 measured 2.5 by 4 cm. with petioles i to 2 cm. long, in the normal 

 specimen. The normal petioles were curved downward throughout 

 their entire length, but most sharply near the laminae in such man- 

 ner as to bring the outer (lower) surface of the leaf uppermost, at an 

 angle of 45° with the vertical. The etiolated stems on the same 

 date were about 15 cm. long and upright. Later the normal stems 

 began to show marked movements and twine about supports while 

 the etiolated stems became weak and dependent, finally reaching a 

 length of 1.7 meters, far in excess of that of the normal at a much 

 later stage. 



The terminal portion of etiolated stems remained apogeotropic 

 and the internodes attained a length of 2.5 to 6 cm., showing a 

 marked increase above the normal. The petioles were 5 and 6 cm. 

 in length, which is also much more than the normal. The etiolated 

 petioles assumed an angle of about 38° with the stem, and did not 

 exhibit any form of geotropic response. The laminae were folded 

 together with the upper (inner) faces appressed. The number of 

 stomata on etiolated examples was much less than in the normal. 



The etiolated stems attained a greater diameter than the normal, 

 due chiefly to exaggeration in the size of the elements in the cortex 

 and pith. The heavy thickening of the walls of the cortex and epi- 

 dermis of the normal was notably lacking in etiolated specimens. The 

 pericycle was notably thinner, with the elements less heavily 

 pitted. The entire stele remained in an embryonic condition and the 

 cambium was much less strongly developed than in the normal. The 

 tubers were allowed to become dry and go into a resting stage in the 

 dark room in June, 1901. In December a second etiolated growth 



