PHYSIOLOGICAL BOTANY. .265 



same subject, occur in the Compt. rend., 1845, i, 861. 

 He first historically adduces Pinot's observation, and 

 adds, that Dutrochet ascribes the phenomenon merely to 

 the pressure of the seed ; he then speaks of Mulder's in- 

 vestigations, which were made at the same time, and 

 which prove the contrary. He next details the results of 

 his own experiments. When the seeds are fixed above 

 the surface of the mercury, the roots penetrate ; but if 

 this is not done, they do so only when the seeds are 

 placed at the side, between the glass and the mercury, or 

 when a layer of the organic matter is deposited from the 

 water, which fixes the young plant. The seeds of Poly- 

 gonum Fagopyrum do not yield any of this matter to the 

 water, hence the roots do not penetrate. 



The Report of the Commission upon these two memoirs 

 is given in the Compt. rend., 1845, i, 1257. Several 

 points which in the memoirs are not described, but merely 

 alluded to, are more detailed. The reporter, Dutrochet, 

 finds fault with Payer's memoir, because he has not 

 stated whether he fixed the seeds above the mercury, and 

 if so, how this was done. The following remarks are 

 quoted from Durand's memoir : When the seeds of 

 Poly gonum Fagopyrum are properly fixed during germi- 

 nation, the radicles always penetrate the mercury. If 

 the seeds are placed in water over mercury, without being 

 fixed, they lose as much in weight as the water which 

 they displace weighs ; hence they exert less pressure upon 

 the mercury, and therefore cannot penetrate it. If, under 

 these circumstances, they are but slightly covered, they 

 penetrate to a certain extent. As has been already stated, 

 the semi-solid layer of precipitated organic matters fixes 

 the little plant at the surface of the mercury, and replaces 

 the artificial fixation. As the seeds of buck- wheat do not 

 yield any organic matters to the water, we need only add 

 a little of some extract to the water to produce the same 

 result. Some experiments performed by the reporter 

 (Dutrochet) follow next. He says, "we have used several 

 kinds of seeds in these experiments, and especially those 



