MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 21 



An interesting example of excessive elongation due to etiolation 

 is given by Krabbe'''' who records that the apothecial stalks oiBaeo- 

 niyces attain a length much beyond the normal when deprived of 

 illumination. 



Vochting"*^ found that light exerted a strong selective influence in 

 the development of shoots ; only the buds favorably acted upon by light 

 showed activity in the formation of branches. Later a reverse in- 

 stance of this action was seen in the potato in which tubers were 

 formed only on organs deprived of illumination. Vochting has car- 

 ried out a large number of researches which bear directly and indi- 

 rectly upon this subject. He found that leaves of etiolated plants 

 brought into light in an atmosphere lacking carbon dioxide did not 

 form chlorophyl, and hence concluded that the growth of these 

 organs is intimately connected with their food-forming operations. 

 Later he also found that the formation of flowers is closely connected 

 with the activity of the leaves, in addition to which light exerts a 

 direct morphogenic effect upon these structures. Diverse reactions 

 were recorded in which some flowers were seen not to open in dark- 

 ness or diffuse light, while others opened but did not reach normal 

 stature. Light also exerted various effects upon the essential parts 

 of the flower. As a result of a series of etiolations of cacti it was 

 found that the form of these plants is largely dependent upon illumi- 

 nation, and that deprivation of light acts as a stimulus which calls 

 out renewed growth. 



Noll"^ relates that etiolated twining plants were capable of grasp- 

 ing supports in the usual manner, such action being ascribed to nega- 

 tive geotropism and circumnutation, an experience that has been 



^^Krabbe, G. Entwickelung, Sprossung und Theilung einiger Flechten Apothe- 

 cien. Bot. Zeitung, 40 : 93. 1S82. 



'"Vochting, H. Organbildung im Pflanzenreich, 2 : 66. 18S4. 



Vochting, H. Ueber der Knollenbildung. Bibl. Botan. i : Hft. 4. 1887. 



Vochting, H. Ueber die Abhangigkeit des Laubblattes von seiner Assimila- 

 tionsthatigkeit. Bot. Zeitung. 49 : 113. 1S91. 



Vochting, H. Ueber den Einfluss des Lichtes auf die Gestaltung und Anlage 

 der Bliithen. Jahrb. f. Wiss. Bot. 25: 149. 1893. 



Vochting, H. Ueber die Bedeutung des Lichtes fur die Gestaltung blattformiger 

 Cacteen. Zur Theorie der Blattsteilungen. Jahrb. f. wiss. Bot. 26 : 438. 1894. 



Vochting, H. Zur Physiologie der KnoUenge wiichse. Jahrb. f . Wiss. Bot. 34 : 

 I. 1900. 



See also, Istvanffi, G. Influence of Light upon the Development of Flowers. 1890. 

 '' Noll, F. Ueber rotirenden Nutation an etiolirenden Keimpflanzen. Bot. Zeitung. 

 43: 664. 18S5. 



