13 Newcombe, Sensitive Life of Asparagus plumosttä. 



The tips of all 3 main axcs and of some of the branches were 

 dead. These shoots were now cut away, and the pota set again 

 in the dark to watch developments. After 4 weeks, 2 of the 

 rhizomes each sent np a slender shoot which continued to grow 

 in the dark for over thrce and one-half months when engagements 

 obliged nie to end the experiment. From materiaJ stored in the 

 rhizome and roots, therefore, two of these plants bad continued 

 growth for a year lacking 5 weeks. The 2 etiolated plants had 

 borne altogether 7 branches. The total length of main axis and 

 lateral branches was for one plant 266 cm, for the other 133.5 cm. 

 This is a truly remarkable growth when one considers how sniall 

 were the rhizomes and roots which furnished the material. 



Basides the great elongation of the main axis, a characteristic 

 of the etiolated shoot is the absence of branches. The appendages 

 of the normal vegetative shoot are the nodal scales, the needle- 

 bearing branches, and the needles. Of these 3, the etiolated shoot 

 bears usually only the nodal scales. These scales seem, on the 

 etiolated axis, to present about the same appearance as on an axis 

 growing in the light. The needle-bearing branches of the first 

 order wonld have numbered on the most of my experimental plants 

 10 to 20, had the plants been grown in the light. On only a few 

 of the scores of etiolated axes have any needle-bearing branches 

 appeared. Those axes that have shown branches were generally 

 dead at the tip. However, 3 etiolated main axes did produce 

 1 to 4 lateral branches each, and with the main tip still living. 

 Somewhat more numerous than the needle-bearing branches are 

 the Clusters of needles on the etiolated shoots. Since the main 

 axis grown in the dark does not generally produce branches, one 

 can look for the Clusters of needles only at the nodes of the main 

 axis. These needles are found on the etiolated shoot at not more 

 than one node in twenty-üve; most plants show none. When pre- 

 sent on the etiolated shoot, their number in a Cluster is greatly 

 reduced, being from one to live, whereas on the shoot grown in 

 the light, they would run from 7 to 25. The reduction in number 

 probably is referable to the lack of elongation, as, with a lens, 

 several very short needles can be seen in the Clusters of the 

 etiolated shoots. 



No matter how long a shoot is kept in the dark, it remains 

 remarkably sensitive to light, considering the fact that etiolated 

 stems generally are more slowly responsive to a heliotropic Stimulus 

 than are those not etiolated. 1 ) A reference to a Single representative 

 experiment will suffice for illustration Five shoots that had been 

 growing in the dark for 8 months were exposed in a window to 

 light reflected from the sky. The temperature was 23°. In an 

 hour all 5 shoots had made strong, positive, heliotropic curves of 

 over 30°. 



J ) Pringsheini, Einfluß der Beleuchtung auf die heliotropische Stim- 

 mung. (Beitr. Biol. Pflanzen. IX. 1907. p. 263.) 



