1912.] PUBLIC DOCUMENT — No. 31. 99 



two characters. The differences in mean l)etween different 

 yronps, more especially in dirterent seasons, is marked. All 

 through the groups of Excelsior L, 1909 was the most produc- 

 tive year, followed in order by 1911, 1910 and 1908. This 

 order is not always followed in the other groups, owing to the 

 fact that dirt'erent planting dates and varying periods of growth 

 caused the plants to experience ditferent weather conditions at 

 corresponding periods of development. These figures bring out 

 in a striking way that fact familiar to all practical men, that 

 productiveness is a delicate and uncertain character and tre- 

 mendously influenced by environmental conditions. 



The 10 plants of Excelsior selected in 1907 have given rise 

 to at least three types of peas referred to as strains A, T), F, G, 

 Iv and B, E, H, J and Variety " C." The groups Excelsior IT. 

 and First of All contain over 100 lines similar to those arising 

 from these 10 plants, but in no case have we over 25 or 30 

 individuals in any one year. We may ask whether we have 

 here anj^ evidence of similar differences. Xo line is as distinct 

 as Variety " C ", but whether there are any of the more similar 

 types, such as the two strains referred to, cannot be positively 

 determined, owing to the small number of individuals grown. 

 If we admit the general application of the very low heredity 

 coefficients shown in Table 11. to all such lines, a coefficient 

 materially greater than these must indicate the presence of dis- 

 tinct strains. Reference to Table I. indicates a possibility of 

 such condition in the case of Excelsior II., but with First of 

 All the figures are about the same as those for single lines ; it 

 should be remembered, however, that the iudicatiojis are that the 

 correlation between seed weight and vine length is less in starchy 

 peas. A study of the means of single lines for the two years 

 available has been made, but is of no value, as the variation 

 obviously due to environment, and the small number of indi- 

 viduals grown, totally obscures any inherited likeness that may 

 exist. The existence of a relatively large coefficient of variabil- 

 ity should indicate the presence of distinct strains, but these 

 figures for Excelsior II. and First of All are variable and in- 

 conclusive. 



The conclusion on this point is that there is some evidence 

 of the presence of distinct strains in l)oth Excelsior II. and 



