( 189 ) 



forces itself between {i,hiss and luci'ciiry and is held fast by the 

 lateral pressnre of the mercm-}'. 



B. It stays in the middle. Here again two cases : 



a. The mercurial surface remains pure. Then the rout does not 

 siidv deeper than it should do on account of its weight. 



b. A resistent, flexible layer is formed on the mercury, consisting 

 of soluble matter of the seed which on evaporation of the water 

 remains on the mercury. The root can then penetrate as this layer 

 sticks the seed to the surface. 



Case a occurred in Dutrochkt's experiments and in tiiose of the 

 committee for Pinot's |)aper ; case /> is that of Pinot and Mr[,DKi{. 

 With MuLDKii buckwheat did not penetrate because it gave oil' little 

 or no soluble matter to the water. So Dukand reduces all the cases 

 of a penetration, greater than the weight, to the tirst-mentioned 

 case, tixation of the seeds. 



It appears from Dutrochet's i-eport that Durand also speaks of 

 "nne adherence capillaire entre la graine et la surface du mercnre", ^) 

 which givTS the seed some support for the penetration of the germroot 

 when the layer of water has almost evaporated. It is not clear 

 wdiether he means the evaporating layer of water or the resistent 

 layer which he later uses for the explanation of the case under b. 



On April 28, 1845, i.e. a month later, a combined report appeared 

 on the papers b}' Payer and Durand. Dutrochet was the reporter. *) 



In the meantime it had become clear that Payer had not distinctly 

 felt the difference between experiments on germination upon mercury 

 wdth loose and with partly fixed seeds. He had not mentioned 

 namely in his Mémoire that his germroots were put through holes 

 in a slice of cork or lay in cottonwool; not till latei-, on April J 5, 

 1845, he had declared this to the committee. Payer moreover 

 declared that he had used the word "penetrative power" only in 

 a superficial ujeaning, not involving a special vital force. 



So Payer's experiments were no longer alarming, especially no^v 

 that Durand had given an explanation of those of Pinot. For in 

 these latter the seedling was stated to have stuck to the surface of 

 the mercury, because on evaporation of the water a sticking-plaster 

 was formed of soluble substances of the seed with meirury. In his 

 re[)ort Dutrochet says^): "La couche dont il est ici cpiestion est une 

 mixtion avec le mercnre des substances oi-ganiques qui ont été 

 dissoutes dans I'eau." "Telle est selon M. Durand, la cause de la 



1) Gomptes iciidus Tome XX 184.") p. 1:203. 



2) Comptcs ien>lus Tome XX ISi.") p. 1257—1268. 



3) Idem p. 1204. 



13* 



