( 192 ) 



mercury was no welcome fact to these theories. In this way arose the 

 fierce controversy between Hofmeister and Fkank ^), concerning wliicli 

 Ave also mention the papers by K. J. C. Muller ^), N. Speschneff ^), 

 Th. Ciesielki '), Sachs ''), Saposhnikow "), and Wachtel '). Frank, 

 like WiGAND, derived from De Candolle ") the erroneous idea that 

 PiNOT lixed his seeds ^), and for the rest entirely embraced the views 

 of Durand and Dutrochet "). To the loose lying seeds none of 

 them paid attention nor is anything found about them in later 

 text- or handbooks. 



In 1899 Dr. A. Schober gave a historical synopsis of the Aarious 

 hypotheses on geotropism in which he also deals with the experi- 

 ments on germination u[)on mercury "). He docs ]u)t deal with 

 loose seeds in it however. 



EcLyh I nation of the phenomenon. 



The [)enetration of the roots of entirely freely floating seeds into 

 mercury has been stated by few investigators only. From the 

 preceding historical synopsis it would appear that this was done 

 only by Plnot and Wigand. 



Mulder, Goeppert and Payer gave support to the seed, by })utting 

 the roots through holes in a slice of cork (Mulder and Payer), in 

 a wooden cross (Goeppert), or h\ placing the seeds in or on a 

 [lug of cottonwool (Payer). Hereb}^ the frictiojial resistance against 

 upward movements was iiicreased and also the circumstances at the 

 surface of mercury and water were modified, so that the seeds were 

 less easily lifted out by u[)ward pressure. 



So I repeated the experiments as Pinot and Wigand had made 

 them. Altliough Wigand gives no dimensions, yet one can see from 

 his description that he did not use such small troughs of mercury 



1) Bot. Zlg. 1SG8 and 18G9. 



2) Bot. Ztg. L869, 1870 and 1871. 



3) Bol. Ztg. 187Ü. 



-^) Corn's Beitrage zur Biologie der Pflanzen 1, 2 1872. 



5) Alb. des bot. Inst, in Wiiizburg I, 3 1873. 



6) Report in Bot. Jahresbericht XV, 1 1887; less extensive in Bol. Ccnlralblatt 

 Band 33, 1888. 



7) Bot. Gentra'blatt Band 63, 1895. 



^) Physiologic végétale 11, 1832, pag. 82. 

 •J) Beitiage zur Pflanzenphysiologie, Leipzig 1808, pag. Ö. 

 1 ) Idem pag. 22. 



11) Die Anscliauungen libor den Gooti-opisnins der Pflanzen soil Kmüiit. Ham- 

 burg 189!). pp. 9 and 18. 



