Changes of Volume in Dry Seeds and Water. 173 



The variation in the total volume might in fact be due to a 

 variety of causes, and since seeds have specific structure, it 

 need not follow the same course for all seeds. In regard to the 

 first increase of total volume, this might be the result of the 

 ■slight rise of temperature when dry seeds absorb water. Hence 

 the experiment was repeated with the peas and water at the 

 same original temperature (13.6°C.), the mixture be- 

 ing well stirred to remove any adhering air bubbles. 



Temperature. 



Time. 



Total Increase or 

 Decrease of Volume. 



13-7°C. 

 14 ^"C. 



14-8°C. 



10 a.m. 

 12.10 p.m. 

 3.20 p.m. 



0-Oc.c. 

 + 6-9C.C. 

 + 3-9C.C. 



In this case a pronounced contraction of volume took place, 

 Avhile the temperature was still rising. The fact that the altera- 

 tions of volume are far greater than any fluctuations due to 

 'Changes of temperature can also be shown by direct estimation. 



Using a bottle of 1050 c.c. capacity, with a tube attached, of 

 which 10 cms. =2.4 c.c, the actual expansion of the water can 

 he calculated from the formula — 



where a=15xlO-« between 10°C. and 20°C. 



The increases of volume per 1°C. at various temperatures are 

 given. 









Estimated Increase 

 of Volume. 



Observed Ris e 

 in Tube. 



Between 



10-12°C. 





0'1056c.c.=0-44cms. 



. 





12-14°C. 





0-1416c.c.=0-59cms. 







14-16''a 





0-1512c.c.=0-63cms. 



• 68cms. 





16-18°C. 





0-1824c.c.=0 -Teems. 



" 1 0-82cms. 





18-20°C. 





0-1920c.c.=0-80cms. 



In spite of the fact that the observed rise only gives the ap- 

 parent expansion, it is greater than the theoretically calculated 

 absolute expansion, but the methods used were not very re- 

 fined, and were merely intended to show that the fluctuations of 

 volume due to slight changes of temperature are small compared 

 with those caused by the swelling seeds. 



The increase of total volume with swelling peas is most pro- 

 nounced when the seed coat has become markedly wrinkled, sug- 



