WHITE— STUDIES OF INHERITA^iCE IN PISUM. 579 



mutations and were subsequently shuffled among a large number of 

 forms, largely through artificial crossing. From the lack of inter- 

 mediates and from their Mendelian behavior, it is almost inconceiv- 

 able that such characters as non-parchmented pods, lack of tendrils, 

 pink flowers and emerald foliage could have originated in any other 

 manner. 



Selection. 



In the American Cyclopedia of Horticulture, under peas, L. H. 

 Bailey states that varieties of peas left to themselves soon lose their 

 distinctive characteristics, because of their great variability. This 

 statement is contrary to all the information I have found in the writ- 

 ings of English horticulturists and others on peas (22, 42, 51, 57.5, 

 9G, 72). In fact, most of our new varieties of peas are obtained 

 through crossing, there being so little variability in varieties by 

 which one may bring about improvement through selection. 



In the work at the Svalof Experiment Station, improved varie- 

 ties are secured through selection, but in reality this is simply isola- 

 tion of pure lines which have either arisen unnoted as mutations, 

 or as unselected segregates from crosses far back. Tedin's (24) 

 character basis by which he isolates new forms is the average weight 

 of seeds, their number per pod and the total number of pods per 

 plant, etc. Upon isolation, these new forms immediately form 

 constant varieties. 



Fruwirth (34) is the only one who has made a modern scien- 

 tific study of selection in peas. The Blauhiilsige variety, as already 

 stated, has either wholly purple pods or purple pods streaked with 

 green. Both color types occur on the same plant and some plants 

 have only purple pods. The seeds of this variety are pure purple, 

 purple flecked with greenish yellow, yellow green flecked with pur- 

 ple or wholly greenish yellow. All types occur on the same plant or 

 each on separate plants, but the progeny of each type give rise to 

 all the other types. After 10 years of pure line selection and 2 

 years of mass selection for a pure purple-seeded race, no results 

 have been secured. Selection toward a pure constant green-seeded 

 race also resulted in failure. Selection for the same length of time 

 toward a pure constant green-podded race gave only negative 

 results. 



PROC. AMER. PHIL. SOC. , VOL. LVI, LL, JANUARY 8, I918. 



