752 MINNESOTA BOTANICAL STUDIES. 



TITLES TO WHICH REFERENCE IS MADE. 



I. Czapek : UeberZusammenwirkung von Heliotropismus und Geo- 



tropismus. Sept. a. d. Sitzungsber. d. Kaiserl. Akad. d. Wiss. 

 i. Wien. Math-naturl. CI. 104: Abth 1. March, 1895. 



II. Detmer: Ueber Photo-epinastie der Blatter. Bot. Ztg. 1882. 



III. Detmer : Pflanzenphysiologische Prakticuru 2nd ed. p. 427. 1895. 



IV. Frank, A. B. : Die nati'irliche wagerechte Richtung von 



Pflanzentheilen, elx. 1870. 



V. Vines: On Epinasty and Hyponasty." Ann. Bot. 3:415-437. 1889- 



1890. 



EXPLANATION OF PLATE. 

 Plate XL. 



Taraxacum grown in normal position in darkness. The young 

 leaves are vertical or nearly so. The older leaves have remained 

 in a position variously approximating the horizontal. 



Taraxacum grown in inverted position in darkness. The younger 

 leaves have curved toward the roots and grown vertically upward. 

 The older leaves have approximately retained their original posi- 

 tion. 



