MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 55 



Stomata were formed in the epidermis of the etiolated prophyll, 

 which were open when examined in water, and the guard cells con- 

 tained much starch. The length of the epidermal cells in the prophyll 

 was to that of the normal as i8 to 12. Similar relations were found 

 in the epidermis of the petioles, while the epidermal cells of the 

 scape did not differ widely from the normal in measurement. It is 

 to be seen therefore that the excessive elongation of the aerial organs 

 of Arisaema trifhyllwn is accompanied by a multiplication of the 

 epidermal elements, which are of slightly increased size. The sur- 

 face of the prophyll is covered with rods of waxy exudation in the 

 normal, which are lacking in etiolated specimens. (See Fig. 16.) 



Upon the maturity of etiolated aerial organs the plastic material 

 was withdrawn into the corms, which increased by a thin layer above 

 and cut off a thicker la3'er below, so that upon the ripening of the 

 corms they were smaller than at the beginning of the test owing to 

 the consumption of some of the material in the work of growth and 

 transpiration. The alterations in the chemical composition of the 

 aerial shoots and corms are shown in the analyses given below. 

 After a resting period of a few months the corms might again be 

 started into renewed activity which resulted in the formation of one, 

 or sometimes two leaves only, with no flower. Third and fourth 

 etiolations might be made in the same manner, in which only single 

 leaves of diminishing size were formed. Half of the original num- 

 ber of corms survived the third etiolation, and a small proportion 

 were still alive and apparently sound after the fourth in darkness, 

 but no further growth could be secured from them. It is probable 

 with more attention to cultural details of temperature, especially dur- 

 ing resting periods, that even longer endurance to deprivation of 

 illumination might be observed. The resting periods were shortened 

 by the treatment given the plants in such manner that four growths 

 were made in three calendar years. 



The repeated growth in the dark was generally in the same ter- 

 minal bud, but in some instances its destruction would result in the 

 accelerated increase of two of the lateral buds which formed two 

 small corms at the expense of the older one. It was noted in the 

 repeated etiolations that the formation of roots was very sparing, the 

 chief energy of the plant being directed to the construction of petioles. 



The germination of seeds in darkness is followed by the forma- 

 tion of an etiolated leaf, which has a petiole longer than the normal 



