l6 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



Vaiicheria sessilis germinating in darkness produced chlorophyl. 

 Amai'yllis formosissima produced normal flowers in darkness but 

 with altered colorations. The length and thickness of roots of 

 etiolated plants was less than those grown in light. The total length 

 of the roots of an etiolated Phaseolus vulgar e was 700 mm. Total 

 length of illumined roots with etiolated shoot 1,254 mm. Total 

 length of root system with entire plant illumined 6,276 mm. Total 

 length of root system with illumined shoot and darkened roots, 

 3,256 mm. These measurements were made on plants grown in 

 water cultures. The roots of an etiolated specimen of Helianthus 

 annmis measured 974 mm., and in an example with etiolated shoot 

 and illumined roots the latter gave a total measurement of 1,252 mm. 



Mer^^ found a correlation existed among the members of the 

 shoot by reason of which the excessive elongation of one was ac- 

 companied by the lessened growth of others. He concluded that 

 plants with a basipetal mode of development were unable to extend 

 these organs to their normal position. Internodes and petioles be- 

 come longer in darkness by reason of lessened tissue tensions. The 

 shortness and non-development of branches and other organs was 

 attributed to lack of nutrition. 



Rzentkowsky ^'^ reported similar correlations expressed in terms 

 of rate of growth. He also found that etiolated plants take up less 

 mineral matter than normal ones, a fact probably resultant from the 

 lessened transpiration. 



Borodin ^^ estimated the respiration of branches of Crataegus 

 inonogyna and Spiraea opulifolia in darkness and found that the 

 quantity of carbon dioxide exhaled was much increased during the 

 period immediately following deprivation of light. Twelve hours 

 later the rate of liberation of this gas had decreased to half the 

 normal, and 24 hours later to one third. The normal rate was 

 quickly resumed when illumination was restored, presumably due 

 to the formation of material available in respiration, according to 

 the author. 



■'"'■^Mer, E. Recherches sur les anomalies de dimensions des entre-noeuds et de 

 feuilles etiolees. Bull. Bot. Soc. d. France, 22 : 190. 1875. 



5'Rzentkowsky, T. Untersuchung iiber die Entwickelung des etiolirten Phaseolus 

 itiultijiorus. Mitth. a. d. Univ. z. Warschau. Abstract in Bot. Jahresber. 4 : 745. 1876. 



^* Borodin, J. Physiologischer Untersuchnng iiber die Athmung der bebljitterten 

 Sprosse. Arb. d. St. Petersb. Ges. d. Naturf. 7 : i-i 14. 1876. Abstract in Bot. Jahres- 

 ber. 4 : 919. 1876. 



