

VITALITY AND GEEMINATION OF SEEDS. 235 



through a series of flasks containing a solution of caustic 

 soda in order to remove all traces of C0 2 and then after 

 passing over the seeds was led through barium hydrate 

 water. Any C0 2 evolved from the seeds will throw down 

 a white precipitate of barium carbonate in the barium 

 hydrate solution. Air was allowed to pass through for a 

 few hours and then sufficient water to cover the seeds was 

 poured into the flask containing them by means of a third 

 tube leading into it, which was then sealed up.* Similar 

 seeds were at the same time placed in water in order to 

 determine how long the water takes to thoroughly pene- 

 trate them. Air was now drawn through the flasks every 

 15 minutes for a quarter of an hour until the evolution of 

 C0 2 was detected. 



The temperature was 18° C. during all the experiments. 



It was found that with Peas the first marked discharge 

 of C0 2 occurs 8J- hours after the water has been poured 

 over them, though slight traces can be detected half an 

 hour earlier. 



After a single hour's immersion in water the seed coat 

 is markedly wrinkled, showing that water has passed 

 through it, whilst in from 2 to 3 hours in most cases the 

 coat is separated from the cotyledons by a distinct layer 

 of water. This is because the water passes more rapidly 

 through the seed coat, than it does into the cotyledons 

 and hence accumulates between the two, stretching the 

 seed coat. 



Later on the cotyledons swell up and in from 5 to 6 

 hours are entirely soaked. On drying the seed, removing 

 the integument and breaking the cotyledons across, the 

 broken surface is seen to be quite moist and watery. It 



* In arranging the apparatus for these experiments and in preserving 

 absolutely airtight connections the assistance of my brother, Mr. R. J. 

 Ewart, was of great use to me. 



