VITALITY AND GERMINATION OF SEEDS. 237 



seeds in water and the emergence of the radicle is about 

 24 times as long as the duration of the latent period. 

 The times given by the above experiments are of course 

 merely approximate, being really the shortest possible 

 duration the latent period can have. It is probable that 

 the latent period should be calculated as commencing not 

 from the complete soaking of the seed but from the first 

 penetration of water. If this were so the latent periods 

 of germination of the Peas and Haricots would be from 6 

 to 7 hours and from 8 to 9 hours respectively. 



Similar experiments were performed with Hemp as an 

 example of an oily seed. Here the first protrusion of the 

 radicle takes place in from 15 to 20 hours, the first evolu- 

 tion of C0 2 in 5 hours. It is very difficult however to tell, 

 owing to the oily nature of the seeds, when the central 

 contents are soaked. If half of the husk is floated on 

 water inside uppermost and a few particles of sugar are 

 placed on the upper surface, these are seen to melt in 

 under 10 minutes, proving that water has passed through 

 the husk in this time. In some cases the passage through 

 of water takes slightly longer than this but in all cases 

 the hard and woody layer which forms the main part of 

 the husk and which protects the soft internal contents 

 from injury must be very readily permeable by water. 

 The latent period will therefore be, allowing for the factors 

 previously mentioned, at least 4 hours in duration if 

 calculated from the first penetration of water. The latent 

 period of germination of Hemp is therefore considerably 

 shorter than that of Peas. 



It is possible that in oily seeds, such as Hemp, the 

 breaking down of the protoplasmic molecule into its 

 constituent compounds is not so complete as it is in a 

 starch containing seed such as a Pea. Hence the latent 

 period of germination during which the protoplasmic 



