BuTLEK AND Shkeidan — Accouut of a New Oedanometer. 465 



that of live seeds. The amount of water absorbed is iudependent of the 

 temperature, but tlie rate of absorption is increased by the rise of tem- 

 perature. The amount of water absorbed by a seed varied even in 

 specimens of the same species, still more so between seeds of a different 

 species. 



He was unable to determine any law whicti a priori would indicate the 

 absorptive powers of the seed. 



There is no recognizable ratio determinable between the volume, or weight, 

 and the percentage of water absorbed by the seed. 



During absorption of water, the increase in volume of the seed is less than 

 the volume of water absorbed. (To this there is an exception ; seeds which 

 become rugose show a relative dilatation during the early stages — Coupin.) 

 Owing to this phenomenon, it is impossible to estimate tlie pressure of swelling 

 seeds by the simple expedient of placing them in a closed vessel of water 

 attached to a manometer, since there would be a volume reduction and not an 

 increase. In another paper Coupin (2) states, in reference to the variability 

 of the absorptive power among seeds — " La seule chose geuerale que Ton 

 puisse dire k cet ^gard est que chez certaines graines, telles que les E^ves et 

 les Haricots, le pouvoir absorbant est plus fort chez les echantillons de petite 

 taille, tandis que chez d'autres, telles que les graines du Lupin et les caryopses 

 de Mais, le pouvoir absorbant est plus fort chez les echantillons de grande 

 taille." 



Gain (7) carried out some investigations on the same subject ; he studied 

 especially the absorptive power of seeds grown under conditions of varying 

 humidity. His conclusions are summarized in the following quotations : — 

 " Le poids des graines etant seulement la resultante d'un grand nombie 

 d'influences, il n'y a pas de relation direete entre ce poids et le pouvoir 

 absorbant. II y a au contraire une relation que parait etre tres" important 

 entre la concentration des liquides internes au moment de I'emmagasinement 

 des principes de reserve ; plus I'eau a et^ abondante a ce moment, moins 

 le pouvoir absorbant sera eleve a I'epoque du gonflement ... If faut en outre 

 remarquer que les graines qui se ferment tres tardivemeut, lorsque la 

 plaute est deja dans un stade de dessication avancee, sont aussi dans des 

 conditions tres differentes de celles dont disposaient les premieres graines 

 formees." 



The first apparatus which we used to estimate the force exerted by 

 swelling seeds was set up for class demonstration. 



Although the instrument is simple in design, and consists of materials 

 easily obtainable and readily put together, it provides a striking demonstra- 

 tion of the force generated by swelling seeds. 



We believe a brief account of it may be of some pedagogical interest. 



