1 28 Pht/tilolof/i('((l Prr-(h:tt'rm in at ion 



The question of probable error in agricultural experiments is also 

 important^. Thus Soule and Vanatter(r)7^ working with wheat carried 

 out an experiment for three years with continuous selection and found 

 an average difierence in yield at the end of three years between large 

 and small grains of 5-18 bushels per acre in favour of the large grains, 

 but when the experiment was continued on different plots in the two 

 following years the divergence in yield was no more than 0-32 bushels 

 per acre in favour of the large grain. 



In quoting results of various workers with regard to the better yield 

 obtained by the use of large seed we will confine ourselves as far as 

 possible to those in which equal numbers of light and heavy seeds have 

 been sown. 



The following are some of the results obtained by C. A. Zavitz(S2) 

 (Table VI). He selected seeds of three grades, viz. large, medium-sized, 

 and small. For grade I none but well-developed grains of large size were 

 selected ; for grade II the grains selected were of uniform character, 

 plump, and of medium size; while for grade III none but sound, plump, 

 and apparently good seeds of small size were used. In the selection of 

 large plump grain | lb of each class was carefully weighed and counted 

 and a corresponding number was then taken of the medium-sized 

 and of the small plump grains. The dift'erent selections were sown upon 

 plots of similar size. 



Table VI. 



Yield of grain per acre from 



, -' . 



Number of Grade I Grade II Grade III 



Crop years of tests Large .seed Medium -sized .seed Small seed 



Oats 7 ()2-0 bushels 54-1 bushels 46G bushels 



Barley ... 6 53-8 — 50-4 



Spring wheat 8 21-7 -— 18-0 



Winter wheat 6 4(j'J — 40-4 



Zavi'tz(82) continued these experiments for several years, each year 

 selecting his seed from a common stock of grain sown in the Ontario 

 Experimental Station Farm in the manner described above. The averages 

 of the results thus obtained are tabulated below . 



Zavitz believed that in selecting heavy seed and obtaining from it a 

 bigger yield he was dealing with a hereditary factor, either for vigour 

 or for size of seed. In an experiment with oats continued for 13 years 

 with continuous selection he (^3) selected his seed for size, plumpness, 



* "The Interpretation of the llcsults of Agricultural Exporimonfs." Snpiil. lo Jniirn. 

 Board of A fj lie, London, Nov. 1911. 



