1915] BARTLETT—MUTATION IN OENOTHERA 117 
none of the seedlings had been discarded. It must be remembered 
that each pan is a fair sample of a whole culture, for the seedlings 
were pricked off when very small and were taken from the seed pan 
as they came, with no attempt at sorting. 
a 
ee x 5 hin nae Soe 
pa oases = nd ane ie 
— 
Fic. 13.—F, progeny of Lexington C, Oenothera pratincola (pan 17 of the progeny 
of C-52); one example of mut. xummularia, C-52-28, is shown; the remaining plants 
are typical. 
Figs. 5, 6, 12, 13, 14, 15, and 17 show 7 of the 50 occurrences of 
mut. nummularia in cultures aggregating 13,035 plants. Three 
more of the original plants of this mutation are shown in figs. 3, 4, 
and 16. The figures showing entire pans should give a fairly clear 
idea of what the writer interpreted as fluctuating variation. It is 
believed that very few if any mutations escaped detection in the 
