W. Bateson and Carolink Pklijow 17 



to iinperfict sortini^'. This suggestion howevc;r h;us proved i(uitc 

 ciToneous. 



We began our experiments by grading the seeds of a comniercial 

 sample according to size. We found that the proportion of rogues is 

 actually nnich smaller among the plants raised from the largest seeds. 

 For example, 302 largest seeds from D. A. and 149 from E. G. gave no 

 rogues ; 119 from N. P. U. gave one rogue : but occasional rogues came 

 among the plants both from the medium and the small seed samples. 

 Owing however to fluctuation in size no even approximately accurate 

 sorting can be made in this way. 



In D. A. the average weight of well-developed seeds was found to be 

 •41 g. for the types (9 plants) and 'ST g. for the rogues (5 plants). In 

 E.G. these weights were "41 for the types (11 plants), and •:34 tor the 

 logues (23 plants)^. These differences are considerable, but many type 

 seeds fall much below the rogue average and the seeds of an occasional 

 rogue surpass the type average. In most varieties no doubt by choosing 

 only the very finest seeds the rogues could in general be avoided, but 

 genetic purity cannot be thus attained. 



As to the production of the lower forms (i.e. rogues or intermediates) 

 from the finest type plants the details are evidently different for the 

 several varieties ; and within the same variety, strains descending from 

 different individuals differ considerably in the liability to throw mgues- 

 The labour of rogueing pea crops is so great that the permanent elimi- 

 nation of rogues would be a matter of considerable economic iinpnrtance 

 to seed -growers. From our e.xperience however the prospect of attaining 

 that object in the case of the large-leaved varieties at least does not 

 seem very good, though from the great difference between strains a 

 relative purity may perhaps be reached. 



The results of sorting the seeds led us to think that it would be 

 possible to raise a pure strain of types. As regards E. G., though of the 

 typical plants raised from the largest seeds some gave families exclu- 

 sively typical, iithers threw (jccasional plants of the lower classes. For 

 example, a type-plant in 1911 gave a family (about 60 plants) in 1912 



' Certain rogues no doubt are thus perpetuated. For instance, in the case of Veitch's 

 Perfection, a wrinkled pea beUeved to throw a rouHd-seeded rogue, though all round seeds 

 are carefully picked out, experiment showed that the perpetuation of the round-seeded 

 plants was due to the fact that the seeds at the apex of the pods are often so much 

 dimpled as to pas.s for type seeds, and thus escape the sorters, giving rise of course to 

 round-seeded plants when sown. 



- The intermediate plants, spoken of later as class .3. gave an intermediate weight, 

 averaging -HT g. (11 plants). 



Journ. of Gen. v 2 



