154 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. . 



apical portion of the frond remained inactive. The other pinnae were 

 curled with the lower outer surfaces outward. 



Etiolated forms placed in light first assumed a position by which 

 the terminal portion was carried more or less horizontal, and some 

 expansion of the pinnae ensued, which however did not reach normal 

 stature. 



Populus Simonii Carr. 



Some small trees of Populus Simonii 3 and 4 meters in height 

 were brought into a cool house on December i, 1901. Two weeks 



later several were removed to the 

 control house and one to the dark 

 room. Within a fortnight both 

 showed signs of activity. The 

 branches showed a tendency to de- 

 velop the buds near the apex and 

 base most strongly, the terminal 

 bud making the greatest amount of 

 elongation in both the normal and 

 etiolated examples. A month after 

 the beginning of growth the 

 branches arising from the basal and 

 middle regions of a normal branch 

 showed 1-3 internodes with a 

 total length of not more than 4 cm. 

 The etiolated buds developed 

 branches three or four times as long 

 in similar regions, and the terminal 

 etiolated buds developed branches 

 with a length of 30 cm. or more, in 

 some instances. The normal term- 

 inal bud sent out branches not more 

 than ID cm. in length, and with four 

 internodes. The etiolated terminal 

 branches showed eight internodes 

 which were sometimes as much as 

 50 per cent, longer than the nor- 

 mal. Similar relations were found 

 between the normal and etiolated 

 branches over the entire plant. 



Fig. 114. Leafy branch of Populus 

 Simoni. Normal. 



