6o MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



tion of water to the cultures, which was given as the state of the 

 cultures seemed to demand it. The same influence would also be 

 operative in the illuminated cultures. It is therefore certain that 

 Arisaejiia triphylhim does not exhibit a daily periodicity of growth 

 independent of variations in temperature, and that the rate is not 

 notably influenced by light; if light does retard, or accelerate the 

 rate it is masked by the superior influence of temperature and trans- 

 piration (see Figs. 19, 20, 22, 23, 24 and 25). 



Petioles and scapes which had ceased to elongate at a rate of 

 more than a fraction of a millimeter daily were removed to the dark 

 room when the temperatures of the illuminated room and dark room 

 were equal, and growth was quickly renewed, an elongation of 14 

 to 16 mm. being made in four or five days. Such additional growth 

 was undoubtedly facilitated by the higher relative humidity of the 

 dark room, but must have been induced by the stimulation of dark- 

 ness (see Fig. 21). 



Etiolated specimens which had attained maturity were brought 

 into a lighted room and found to be capable of expanding the leaf- 

 lets, which however did not attain the average size of normally 

 developed organs. The erect and recurved hoods of the spathes 

 retained these positions. Variations in the final positions of the leaf- 

 lets and general aspect of such illuminated etiolations are shown in 

 Fig. 14. In one instance a second flower scape was developed 

 from an etiolated plant after being brought into light. 



Determination of Water, Dried Material and Ash. 



The following series of determinations were made to ascertain the 

 relative proportion of the main groups of constituents in normal and 

 etiolated material. 



I 



Resting corms in a dried condition were placed in a moist cham- 

 ber for a day, after having been out of the soil for three months. 

 The outer dead coats were rubbed off with a cloth, and a corm of 

 medium size with the half of one of the maximum size were weighed, 

 and the various desiccations and combustions gave the following data ; 



Weight of fresh material i3'995 grams. 



" '^ dried " 3-400 "• 



" " ash .108 " 



