}0 



PInisioliKjuud Prr-dctcini indtHni 



confined to size of seed, but was also made on the basis of colour- 

 differences such as are known to be often associated with hereditary 

 factors. 



We may turn now to an author who has conducted careful experi- 

 ments with wheat in which equal numbers of small and of large grains 

 were sown and in which the percentage of plants that grew was deter- 

 mined. Grenfell(25) describes his selection as between plump and 

 shrivelled grains. These were sown in alternate rows, 150 grains to a 

 row. He notes in the first place that the plants from the plump grains 

 soon began to get a start of the others and kept ahead all through. 

 The percentage of plants that grew from the plump grains was also in 

 excess of that from the shrivelled. The following table gives his results 

 from which it appears that the average yield per acre from plump 

 seed-grain is 9-8 bushels as opposed to 7-5 bushels from shrivelled 

 seed-£rain. 



From the point of view of physiological pre-deterniination the sort 

 of difficulty involved in interpreting his results and the results of many 

 other authors who have worked on the same lines with cereals, is clear; 

 obviously the number of plants that grew and the amount of tillering 

 per plant, which combined give the number of heads per seed sown, 

 greatly affect the results^. 



From Grenfell's figures, however, we are able to work out the relative 

 yield "per head and the relative yield i)er fJanl from plump and shrivelled 

 seed respectively. 



1 Driesdorf (Zeitsch.J. d. Pror. Sachsen, 1868) observes that in April winter wheat from 

 large seed-grain showed greater tillering and a deeper green colour than that produced 

 from small seed-grain. 



