Atkins — The Absorption of Water by Seeds. 



43 



89-5 per cent, and rose to 125'6 per ceut. A desiccated bean was fonnd to 

 have a density of I'lSO initially, and after 310 hours in water it had fallen 

 to 1'119. The density of desiccated bean substance was determined by 

 placing the ohopped-up material in a specific-gravity bottle with mercury. 

 The value thus obtained, 1"523, enables us to calculate the size of the internal 

 liollow in the seed — about 33 per cent, of the whole volume. 



Titration Method. 

 In order to detect the presence of a small area of semipermeable 

 membrane, which might have escaped notice by the weighing method, 

 owing to the difference between seed and seed, A. J. Brown's device was 

 adopted. Quantities of bean seeds, as boiight and after desiccation, were 

 placed in measured volumes of normal sulphuric acid, 49 grms. per litre, 

 decinormal iodine in potassium iodide, 12*7 grms. of iodine per litre, and 

 decinormal sodium chloride, 5'85 grms, per litre. They were left in these 

 solutions for forty-three hours ; then 25 c.c. was di'awn oif from each 

 and titrated, the chlorides were evaporated to dryness and ignited to destroy 

 organic substances which interfered with the silver nitrate and ammonium 

 thiocyanate methods of titration. In each case one hundred beans were 

 used, weighing 62 grms. as bought. Of this sample 98 per cent, germinated. 

 The hundred desiccated beans of experiments 4 and 10 weighed 47 grms. 

 In this sample 100 per cent, germinated before drying. 



SCIENT. PEOO. E.D.S., VOL. XII., NO. IV. 



