[Proc. Rot. Soc. Victoria 34 (N.S.), Pt. II., 1922]. 



Art. XVIIi. — On the Changes of Volume in a Mixture of 

 Dry Seeds and Water. 



By ALFRED J. EWART, D.Sc, Ph.D. RR.S. 

 {Professor of Botany and Plant Physiology in the University of Melbourne). 



[Read 8th December, 1921]. 



If a quantity of dry peas is placed in a bottle filled with 

 water, and provided with an open upright tube, it will be noticed 

 that as the seeds swell the level of water in the tube rises, indi- 

 cating a total increase of volume, and that after several hours 

 the level of liquid in the tube falls again. The following obser- 

 vations illustrate this: The bottle used had a capacity of 1050 

 c.c, and 10 cms. of the erect tube contained 2.4 Cc. Peas 

 were dried at 80° C, and the bottle two-thirds filled with them, 

 and then filled up with water. The temperature of the peas was 

 20° C, and of the water 13.6. The increase or decrease of volume 

 was measured from the height of liquid in the tube. The total 



Temperature. 



Time. 



Total Increase or 

 Decrease of Volume. 



16-3°C. 



12 a.m. 



0-Oc.c. 



— 



12.30 p.m. 



+ 0-36 c.c. 



16-3°C. 



3 p.m. 



+ 5 -60.0. 



16-4°C. 



3.50 p.m. 



0-Oc.c. 



15-8°C. 



10 p.m. 



-18 -Tec. 



13-8°C. 



10 a.m. 



-10 -80.0. 



volume therefore first increases, then decreases by a still greater 

 amount, and finally increases again. The final increase is appar- 

 ent only, and is due to the production of small bubbles of gas 

 by anaerobic respiration. It begins, however, before the bubbles 

 actually appear. 



This simple observation has long been known, and has been 

 variously explained. It has even been stated to be a good way 

 of demonstrating the expansion of seeds in water, ignoring the 

 fact that the expansion of the seeds should be proportional to 

 the amount of water they absorb, leaving the total volume un- 

 altered. 



