( 182 ) 



Botany. — ''On the penetration into meren ri/ of the roots of freely 

 f/oatim/ f/erminatinij .seeds." By Ph. \an IIaijrkveld. (Coiii- 

 immicatcd by Prof. J. W. ^Ioll\ 



The first who inentioned that growing germ roots can penetrate 

 into mercury was Jules Pinot in 1829. He placed various seeds in 

 a tliin hiver of water on mercury and ol)served that on germination 

 a number of roots pushed themselves into the mercury. 



His experiments were important in two respects. Firstly from a 

 physiological jjoint of \ic\v : the penetration of the germroots into a 

 liquid of so liigh a specific gravity as mercury proved that during 

 growth considerable forces are de\eloped. And secondly from a 

 ])hysical point of view : the seeds lay loose and yet the gernu-oots 

 were not lifted out (»f the mercury by the u})\vard pressure. 



These two results of Pinot's expei-iments must be clearly distin- 

 guished. On the first much work has later been done ; Sachs and 

 other investigators used mercury repeatedly in order to give a 

 o-reat and unitorm resista,ncc to a dou nwai-d growing root. On the 

 second point, the physical paradox of the root which penetrates into 

 mercury without a hold, no i)uhlication has ai)peared after that 

 of WiGAND in 1854. Pinot himself was only struck Uy the second 

 result of his experiment, the penetration of loose lying seeds. As this 

 phenomenon could not be explained by physical laws, he called iji 

 the aid of vital force, as was still very common in his days. 



The vitalistic doctrine however had found a fierce opponent in 

 DuTROCHET ^). The latter declared the ex[)eriments to be untrust- 

 worthy. vSeveral investigatoi'S, on the other hand, confirmed Pinot's 

 observation. Thereupon Dluand and Dutrochet gave, in 1845, an 

 explanation of the curious fact which was generally accepted. Altliough 

 WiGANU in 1854 assured once more that Pinot's observation was 

 correct and still awaited an explanation, no further attention was 

 paid to it. Pinot Avas often cpu)ted for his first result ; for the 

 phenomena of freely floating seeds at best reference was made to the 

 refutation by Durand and Dutrochet. 



Reading the astonishment of Wigand, when he was obliged to 

 state the correctness of Pinot's observations, I repeated the experi- 

 ments. I found that Pinot was right indeed. The explanation of the 

 seeming physical paradox can nowadays be easily given; a "\ital 

 force" is not needed for it. 



In the older literature on geotropic phenomena one meets with 

 such contradictory opinions about the penetration of freely floating 



1) J. Sachs, Geschichte ilcr Botanik 187Ö. pag. ÖDü. 



