Mutations and Evolution . 
79 
Table I. 
Mutations in (Enothera with an extra chromosome. 
Chro¬ 
Parent Form. 
Mutant. 
mosome 
number. 
Author^ 
lamarckiana, biennis, &c. 
lata 
15 
( Lutz, Gates, 1912. 
( Gates & Thomas, 1914 
lata x lamarckiana ... 
semilata, Gates ... 
15 
Gates & Thomas, 1914 
C incurvata ... 
15 
Gates, 1915a. 
Swedish lamarckiana 
3 lata 
15 
Gates & Thomas, 1914 
(.semilata ... 
15 
rubricalyx X grandiflora 
lata 
15 
rubricalyx . 
lata or semilata ... 
unc’t’d. 
Gates, 1915a, p. 110. 
biennis semigigas X biennis 
unnamed 
15 
De Vries, 1915b. 
lamk. X biennis nanella 
lata hybrid 
15 
De Vries, 1915b. 
lamarckiana ... 
scintillans 
15 
Hance, 1918. 
lamarckiana ... 
albida 
15 
Lutz, 1908, 1917. 
Lutz, 1917. 
lamarckiana 
bipartita . 
15 
lamarckiana 
modified oblonga 
15 
(type 5509) 
lata X lamarckiana ... i 
lamarckiana ... ) 
nanella lata 
15 
> ? f > 
lata X lamarckiana ... » 
lamarckiana ... J 
subovata ... 
15 
5 > 1 * 
Nanella . 
dwarf type 2256 
15 
J * ) * 
lata and lata X lamk. 
type 4499 
Cexilis . ) 
15 
y j yy 
lata selfed . 
} exundans ... ... > 
(.type 5365 ... ) 
15 
yy yy 
lamarckiana . 
type 2806 
15 
yy yy 
lamarckiana . 
elliptica . 
15 (?) 
yy yy 
lata X lamarckiana ... 
rubrinervis,] 
14 + 1 
yy yy 
de Vries 
lata X lamarckiana ... 
aberrans . 
14 + 1 
yy yy 
ABBCDEFG, fertilizes one which is ABCDEFG. Such gametes 
could arise from an - —— meiotic separation in lata in the first 
ABB 1 
AB 
case, and an -—- separation in the second case, the ABB and 
AAB 
AB groups (disregarding the other chromosomes) then uniting in 
fertilisation to form a nucleus with 2 A’s and an extra B, although 
derived from a plant in which there were two B’s and three A’s. 
The chances of this happening are small, especially when we 
remember that lata produces practically no functional pollen 
grains, and that these nearly all have 7 chromosomes. Nevertheless 
it is not impossible. 
In lata x lamarckiana the chances of getting a mutant with a 
new extra chromosome are greater than in lata selfed, for we may 
suppose (1) that a 7-egg, i.e., ABCDEFG, is fertilised by a sperm 
having two members of some other pair than A, the latter condition 
having arisen through an irregular separation involving the non- 
