Changes of Volume in Dry Seeds and Water. 175 



skin absorbing water, and expanding more rapidly than others. 

 This would result in a tendency to a partial vacuum beneath each 

 wrinkle, and this would hasten the drawing in of water, and at 

 the same time increase the total volume of the mixture of seeds 

 and water. If this were so, then under pressure the first ex' 

 pansion should be either greatly decreased or suppressed. 



For this purpose a stout separating funnel was used. Peas 

 and water were introduced at the top, which was then sealed. 

 To the lower end a long-armed U tube was attached. This 

 contained a water column continuous with that in the funnel. 

 Mercury was then poured into the open arm of the U tube until 

 the difference of level was 76 cms. After each reading the mer- 

 cury was brought up to the original level if contraction had taken 

 place, or reduced to the same level with the aid of a pipette if 

 expansion had occurred. The temperature varied within 1°C. 

 during the experiment, a maximum rise of 1°C. being shown, 

 after three hours, when the total volume had begun to decrease. 

 The total initial volume was 1080 c.c. and a two-thirds charge 

 of oven-dried peas was used. 



Time. 





Total Increase 



or 



Decrease of Volume. 



3 p.m. 





[O-Oc.c] 





. 



0-Oc.c. 



3.35 p.m. 





[ + 2-3C.C.] 





- 



-0-lOc.c. 



4 p.m. 





[ + 4-7C.C.] 





- 



-h0-28c.c.* 



4.40 p.m. 





r + 6-,3c.c.] 





- 



+ 0-76C.C. 



5 p.m. 





[ + 2-1C.C.] 





- 



0-Oc.c. 



8 p.m. 





[-2-4C.C.] 





- 



-2-Oc.c. 



9 p.m. 





[-3-Oc.c.] 





- 



-4 -Sec. 



9 a.m. 





[-1-lc.c.J* 





- 



-5-6c.c.t 



10 a.m. 



- 



— 





- 



-5-6C.C. 



* 



Seeds bej 



winning to wrin 



kle 







t Seeds fully swollen. 









Owing to the pressure the final expansion due to the libera- 

 tion of gas bubbles is long delayed. The figures in brackets give 

 the expansion and contractions of a similar volume of peas and 

 water not under pressure. At * gas production began preventing 

 the full contraction of volume. 



It will be noticed that under pressure there is a slight con- 

 traction of volume before the expansion due to the wrinkling 

 of the seed coat begins. This is probably the result of the pres- 

 sure on air in the intercellular spaces of the cotyledons. These 

 are not entirely obliterated on drying, as can be seen by exam- 



