536 
Reginald Ruggles Gates 
Discussion. 
I. History of 0. gigas. 
The fact that 0. gigas bas double the number of chromosomes 
iu tbe parent form, 0. Lamarcliana , (at least in all individuals in 
wbicb a count bas been made sbows tbat its method of origin has 
been different front tbat of any other Oenotliera mutant so far ex- 
amined, and tbe cbromosome number of nearly all is now kuown. 
Tbat this form comes in a different category front the otber mutants 
is also entphasized by tbe extreme rarity of its occurrence as a 
mutant. Only seven individuals liave ever appeared in all cultures 
of which accounts bave been publisbed. The original specinten was 
a mutant front 0. Lamarcliana (De Veies 1901, I p. 157). Gigas 
bas since appeared as a mutant front 0 . Lamarcliana , once in Mac- 
Dougal's cultures (1907 p. 10 , and three times in the cultures of 
Schölten (1908 p. 52), a pupil of DeYries, front commercial seed. 
It appeared on two other occasions in DeYries' garden; once in 
1898 as a mutant from 0. svblinearis (1901, I p. 231) and once in 1899 
front 0. lata x 0. hirteüa. Xeither of tbese plants matured and 
there utay perhaps be some doubt as to whether thev were actually 
tbe same form. 
Tbe history of tbe first gigas individual was carefully recorded 
by Professor DeYries (1. c., I p. 159). It appeared in 1898 in a 
lot of 32 rosettes wbicb bad been selected by bim from a large 
number, wbose ancestors bad been pure Lamarcliana for tbree gen- 
erations. The numbers of Lamarcläana plants furnisbing seed for 
tbese three generations were respectively 9. 6, and 10, so tbat they 
were carefully scrutinized and tbe presence of a previous specimen 
of gigas amoDg tlieni would bave been detected. 
Tbis individual of 0. gigas Professor DeVries found to breed 
true in its offspring, although exhibitiug a wide ränge of variability, 
particularly in its leaf cliaracters. In 1897, 450 plants were pro- 
duced from tbis individual, all beiug like tbe parent, but one wbich 
was dwarfed — 0. gigas naneüa (1. c., I p. 160). One plant in 1899 
was wholly sterile after repeated artificial pollination (1. c., II p. 59). 
Iu tbe culture of 0. gigas by Schölten (1908 , 24 0. gigas nanella 
appeared in 1906 (p. 58), a total of 2 per cent. of the individuals. 
A similar culture in 1907 gave (p. 94) nearly 2 per cent. 0. gigas 
nanella, 1 plant 0. gigas lata (?) and 1 plant 0. laevifolia. Tbis last 
