[ 190 ) 



]K'iiélration de la imliciile (huis Ie merciire lorsqiie la graine est 

 (léposée sur la surface de ce métal euuNcrt d'un peu d'eau ; il faut 

 que la graine soit agglutinée a la surface de ce métal par Ie moyen 

 d'un eiiduit qui s'y forme pour que cette penetration ait lieu. 

 Lorsque le mercure conserve son poli, les radicules ne s'y enfoncent 

 jamais an dela de ce qui est determine par la pesanteur des graines." 



So the paradox had been subjected to known [physical laws. 



The matter seemed to be settled for good and all, when in J 854 

 once more an investigator confirmed Plnot's ol)servalions. 



Albert Wigand at Marburg wrote in his "Botanische Unter.su- 

 chungen" a chapter, entitled "Yersuche über das Richt ungsgesetz 

 der Pflanze beim Keimen" ^). He mentioned in it tlie experiments 

 of PixoT, Mulder and Dutrochet, without quoting the literature on 

 the subject. He said that Pinot and Mulder fixed the seeds l)ut that 

 DuTROCHET let them free and hence obtained a negative result. '') 

 Evidently he derived this erroneous idea about Pinot from Roper's 

 translation of De Candolle's Physiologic \égétale. 



Wigand dared scarcely confess that he also had made seeds 

 germinate when they fioated on the mercury, so firndy Avas he 

 convinced of the impossibility of success in this case. '). 



But the result was undeniable, and so he nevertheless described 

 his experiments. 



The seedlings grew iji a very tliin layer of water on the mercury 

 or on dry mercury in an atmosphere saturated with water-Aapour. 

 Some roots penetrated perpendicularly into the mercury as far as 

 \ "Zoll". ^) Others grew in a slanting direction into the mercury 

 or at first perpendicularly and then more horizontally or the apex 

 came out of the mercury again or it grew horizontally at first and 

 then perpendicularly downwards. A great number of roots remained 

 creeping over the surface. Seedlings that had been taken out of the 

 mercury could be replaced to the same depth. Along the glass wall 

 many roots penetrated. 



For seeds of smaller size than lieans, weight was hardly a factor 

 for the penetration; a seed of garden-cress made scarcely any de- 

 pression in the mercury and yet the root penetrate^l fairly deep. 

 Nor could the reason be found in a greater adhesion of seeds and 

 mercury by the secretion of certain substances. For often mercury 



1) Botc-inische Uulersucliungeu von Dk. Albert Wigaxd, Biauuscliweig 1854 

 pp. 131—166. 



2) Idem p. 136. 



3) Idem p. 137. 



-i) \-l Linien = 1 ZoU = il,Olo mm. 



