38 Newcombe, Sensitive Life of Asparague plumosns, 



V. Light as Related to Unfolding of Branches. 



Goethe 1 ) in his "Farbenlehre", stated that plants grown in 

 darkness did not unfold their lateral buds. Sachs 2 ) contradicted 

 this Statement, but Jost 3 ) found that Fagus süvatica did not unfold 

 its lateral buds in the dark, and Asparagus ylv/mosus follows the 

 behavior of Fagus. In the case of seedlings, hewever, and in the 

 case of shoots growing from the rhizomes, the shoots being reinoved 

 froni light not raore than 6 to 8 days before ready to take the 

 diageotropic positiou, the lateral buds unfold into branches not 

 differing greatly from the normal. This unfolding of the buds of 

 the seedlings and of the other shoots named is to be accounted a 

 correlation when compared with the lack of unfolding in other 

 shoots of Asparagus, since the shoots which unfold their lateral 

 buds in the dark are all nearing the end of the growth of the 

 main axis. This failure of etiolated shoots to unfold their lateral 

 buds cannot be due to a lack of sufficient building material, since 

 the main axis in many of my etiolated shoots grew for more than 

 a meter after the normal time for unfolding the lateral buds. There 

 was therefore enough material for forming the branches, but the 

 plant did not dispose its supply of food for the unfolding of the 

 lateral buds. Similar results are indicated by Sachs 4 ) working 

 with the growth of the leaves of Cucurbita pepo, and by Jost 3 ) 

 working with the leaves of some of the Leguminosae and the 

 branches of Fagus sylvatica. Sachs' explanation of the smaller 

 size of leaves in the dark is that the leaves become diseased; 

 Jost has offered the hypothesis that it is due to the competition 

 for food. There is a third possibility at least, that is that the 

 plant disposes of its supply of food by correlation, correlation 

 here not being equivalent to competition. None of these hypo- 

 theses attempts to show the mechanism of Operation. 



The lack of unfolding of the needle-bearing branches of the 

 etiolated shoot extends also to the needles. Even in seedlings 

 grown in the dark, which unfold the larger branches as well as 

 tho in light, the needles are much reduced in size. The etiolated 

 seedlings, therefore, agree in behavior with seedlings of most plants 

 in failing to develop their assimilating organs in the dark. 



VI. Light as Related to Twining. 



From the experiments already cited, it is evident that if a 

 shoot destined for twining in the light is covered from the light 



') Goethe, Farbenlehre. Sämtliche Werke. Cotta'sche Ausgabe 1840. 

 Bd. 37. p. 208. 



2 ) Sachs, Bot. Zeitung. XXI. 1863. Beilagen, p. 11. 



s ) Jost, Über den Einfluß des Lichtes auf das Knospentreiben der Rot- 

 buche. (Ber. d. D. Botan. Gesellsch. XII. 1894. p. 194.) 



4 ) Sachs, Lectures on the Physiology of Plants. Translated by Ward. 

 Oxford 1887. p. 532. 



