58 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



of the immense reserve energy of plants with storage organs. 

 Such an adaptation would be of great value in plants growing in 

 loose moist soil in woods and meadows. The corms undoubtedly 

 are often covered with soil, humus, or dry leaves to great depths. 

 In such instances the power of excessive elongation of the prophyll 

 would enable the plant to make a strong effort to emerge from such 

 unfavorable conditions, and failing in the first attempt, the trial 

 might be made a second, third," and even a fourth time, with greatly 

 increased chances for survival over the plants which must win the 

 light in the first attempt or perish. (See Fig. 12.) 



Cultures were made in ver}'- diffuse daylight in which the tem- 

 perature was exactly the same as of others in direct sunlight. It 

 was found that the petioles did not show an elongation be3'ond that 

 of the average normal specimen, but the laminae were reduced be- 

 low the average in superficial area, and assumed a curved position. 

 The overarching hood of the spathe assumed the upright position 

 characteristic of the etiolated cultures. (See Fig. 17.) 



A number of studies of the method and rate of growth of the 

 peduncles and petioles were made. To determine the region of 

 maximum elongation, intervals of a centimeter were marked on the 

 petioles and scapes and these intervals remeasured at maturity. 

 The following final lengths show the locations of the greatest growth. 



Petiole. 

 Basal, 3 cm. 6 7 12 10,5 4.5 Terminal. 



Scape. 

 Basal, 7 cm. 545 Terminal. 



It is to be seen that the greatest elongation of the petioles takes 

 place in a region above the middle, while it is basal in the scape. 



Peduncles and scapes have been attached to various auxanome- 

 ters during the course of the experiments, extending over five years 

 and the results, in so far as to periodicity and maximum elongation, 

 have been fairly uniform. A consideration of the facts thus ob- 

 tained forces one to the conclusion that the growth of the peduncle 

 and petiole in light is not characterized by any periodicity depen- 

 dent upon, or influenced by light. The rate of growth was found to 

 increase after 10 A. M. in most instances, or a short time after a 

 rise in the daily temperature customary in greenhouses, which as an 

 after-effect culminated at 6 or 8 P. M. Lesser maxima were induced 



