( 183 ) 



seeds, that it may be useful to give a siiort synopsis of the literature 

 on the subjecl. I shall afterwards compare I he various opinions with 

 the true explanation. 



Historical si/jwpsi.^-. 



On February 23, 1829, Jules Pinot seni (o llie Paris Academy 

 of Sciences a paper on the penetralion ot gei-m roots into mercury. 

 The Academy appointed a committee of three members to examine 

 this paper. 



Pinot repealed his experiments in the ,/jardin du Roi" in the 

 presence of two of the members of this committee. He also showed 

 one member a new experiment, in order to guard his conclusions 

 against possible objections. In a letter to the Academy, dated July 

 27, 1829, he gave a description of it. Neither the paper nor the 

 letter seem to have been printed. But Pinot published a short account 

 of his first paper, together with an extract of his letter, about the 

 new experiment, in the Revue BibliogTa})hique of July 1829 '). 



According to this account he arranged his experiments in the fol- 

 lowing manner -. a little trough, 18 mm. deep and 10 mm. broad 

 was filled with mercury and a thin layer of water poured out on 

 the mercury. The trough stood in a small dish with water o\'er 

 which a little bell-jar was placed. Seeds of Lathyrus odoratus, soaked 

 in water, Avere placed on the mercury Nvith the Iiiluni turned towards 

 the mercury surface. 



The layer of water Avas sufticient to maintain germination, but 

 was on the other hand, as thin as possible in order not to favour 

 rotting of the seeds. Now on germination the roots of the freely 

 floating Lathyrus seeds penetrated to a fairly consideral)le depth into 

 the mercury without lifting the seed. Also Avith other seeds the 

 experiment was successful ; the penetration sometimes exceeded 8 or 

 10 mm. When however the growing little stem was killed l)y a 

 drop of sulphuric acid, the root came to the surface. 



1) Revue Bibliograp]ii(jue pour servir de comi)lémcnt aux Annales dcs sciences 

 naturelles; par M. M. Audouin, Ad. Brongniart et Dumas. Année iSïiO page 94— 90. 



This Revue Bibiiographique only appeared in the years 18:29, 1830 and 1831. 

 With many sj^ecimens each of the three yearly volumes is bound with one of llie 

 three volumes which appeared annually of the Annales des sciences naturelles. As 

 they have a separate pagination however, it i» nol sullicienl to quote the number 

 of the page and tlie volume of the Ann. d. sc. nat., as Hokmeister (1860), Ciesielki 

 (1872) and others do. A. P. De Candolle in his Physiologic végélale II. p. 8:28, 

 note (1) calls this Revue Bibl. wrongly : Ann. sc. nat., Bull, which may cause 

 confusion with the "Bulletin des sciences natmelles et de geologie", which appeared 

 from 1824 (T- 1) hll 1831 (T. XXVII), 



