FIFTEEN- AND SIXTEEN-CHROMOSOME OENOTHERA MUTANTS 73 
De Vries ('09, Vol. I., p. 224) gives a table showing the origin of 
new species from the type, 0. Lamar ckiana. From a first generation 
of 9 Lamarckianas he records 7 generations of descendants through 
0. Lamarckiana (1886-87 to 1899, inclusive) consisting of a total of 
54,334 individuals, of which 834 were mutants, as follows: 
Table I 
Species 
0. La- 
marck- 
iana 
O.nanella 
14 
0. rubri- 
14 or 14+1 
0. lata 
15 
0. albida 
0. scintil- 
Prob"i5 
0. oblonga 
14 or 15 
0. gJgas 
28 
Number of in- 
dividuals . . . 
53*500 
I5S 
32 
229 
56 
8 
350 
I 
Although the somatic chromosome number of 0. scintillans is 
probably 15, the actual number is unknown, hence this type will be 
excluded from our calculations. If oblonga has 14 chromosomes, we 
see that approximately 20 percent of the total number of 15-chromo- 
some forms were neither 0. lata nor lata-Vike individuals. If oblonga 
has 15, then we see that almost 64 percent were neither 0. lata nor 
lata-like forms. But de Vries states that the list is incomplete, as 
only the more important mutants were recorded; furthermore, since 
the records date from 1886, it is probable that even the common 
types were occasionally overlooked in the early years of the work;: 
in fact he says (p. 229) that albida was passed by as a diseased 
form in 1888 and 1890. For these reasons the records of his 1895 
Lamarckiana cultures are perhaps more significant (pp. 262-263). 
Of the total of 10,614 offspring of 0. Lamarckiana he states that 
614, or about 6 percent were mutants, ''of which 0. albida made 
up 2.5 %, 0. lata 1.7 %, 0. nanella i.i %, 0. oblonga 0.7 % 
and the rest altogether o.i %." If we include oblonga and the un- 
named mutants among the 15-chromosome forms, we see that the 
total number of albida plants alone equalled the total number of all 
other 15-chromosome mutants listed, including 0. lata. We will 
assume that some of the unnamed types had 15 chromosomes and 
others 14 and that oblonga also had 14. If such were the cavse, the 
number of albidas not only exceeded the number of latas, but exceeded 
the combined number of 15-chromosome forms not listed as 0. albida. 
It is well known that a large percentage of Oenothera seeds fail to 
germinate in the short time commonly allowed them when sown in 
